**3. The role of probiotics in the prevention and treatment of AD**

The increased prevalence of atopic diseases is nowadays defined as an epidemic. AD is known as the earliest of these conditions, might act as an indicator for the development of IgE-mediated atopic manifestations. Thus, being aware of possible measures, such as probiotic use, to prevent and/or heal atopic disease is essential for the practicing allergist. Here, their role in the prevention and therapy of AD under the recent literature gathered from Medline and Pubmed are discussed. The various effects of different probiotic strains in AD are summarized in table 2.

Maassen et al 38,105 Lctbs reuteri Immunomodulation ↑

Niers et al 37,58,82 Bfdbm Prime neonatal Dendritic cell ↑

Forsythe et al 71 Lctbs reuteri Activate TLR-9 ↑

Braat et al 60 Lctbs rhamnosus Modulates Dendritic cell

Smits et al 61 Lctbs reuteri / casei Prime monocyte-derived

Smits et al 61 Lctbs reuteri / casei Prime monocyte-derived

Kruisselbrink et al 39 Lctbs plantarum Inhibits specific T-cell

Braat et al 60 Lctbs rhamnosus Modulates Dendritic cell

**3. The role of probiotics in the prevention and treatment of AD** 

**Abbreviations**: Lctbs = Lactobacillus; Bfdbm = Bifidobacterium; LGG= Lactobacillus rhamnosus GG; ↑= increase in symptoms or negative effect; ↓= decrease in symptoms or positive effect; ↔ = No change in

The increased prevalence of atopic diseases is nowadays defined as an epidemic. AD is known as the earliest of these conditions, might act as an indicator for the development of IgE-mediated atopic manifestations. Thus, being aware of possible measures, such as probiotic use, to prevent and/or heal atopic disease is essential for the practicing allergist. Here, their role in the prevention and therapy of AD under the recent literature gathered from Medline and Pubmed are discussed. The various effects of different probiotic strains in

Table 1. Various mechanisms for effects of probiotic strains in atopic disorders including eczema are shown from experimental (animal) and clinical (human) studies referred in the

Bfdbm bifidum / infantis; Lctbs salivarius

Sistek et al 41 Lctbs rhamnosus GG

Kim et al 42,62,83 Bfdbm bifidum; Lctbs

Feleszko 63 LGG, Bfdbm lactis (Bb-

Hoarau et al 70

symptoms or no effect

AD are summarized in table 2.

chapter text.

**References Probiotic Strain Effect of probiotic Outcome** 

(LGG) Immunomodulation <sup>↓</sup>

acidophilus TGF-β production <sup>↑</sup>

12) TGF-β production <sup>↑</sup>

**Dendritic Cells**

**Development of Tolerogenic** 

**Toll-like Receptor Stimulation** 

**T-regulatory Cell Production** 

**T-cell Hyporesponsiveness** 

function <sup>↑</sup>

Dendritic cell <sup>↑</sup>

Activate TLR-2 ↑

Dendritic cell <sup>↑</sup>

responses <sup>↑</sup>

function <sup>↑</sup>


The Role of Probiotics in Atopic Dermatitis Prevention and Therapy 367

supplementation with probiotics (LGG), Viljanen et al found significant improvement on the SCORAD index only in "IgE-sensitized -cow's milk -allergic- infants of the atopic eczema/dermatitis syndrome (AEDS). Only in the subgroup of IgE-sensitized children, did the LGG group show a greater reduction in SCORAD than the placebo group but this effect could have been due to a higher baseline score in this subgroup. There was no difference between the groups at the end of 4-week therapy and 4 weeks after therapy was discontinued. Contrary to what would be expected, improvement was seen 4 weeks after discontinuation of therapy rather than during treatment [28,72]. Rosenfeldt et al from Denmark in a study, 2 lyophilized probiotic Lctbs strains (lyophilized Lctbs rhamnosus 19070-2 and Lctbs reuteri DSM 122460) were given in combination for 6 weeks to 1- to 13 year-old (mean age, 5.2 years) children with AD. This study used 2 different Lctbs species in older children. A combination of these was beneficial in the management of AD. Statistically significant improvement in SCORAD score was seen only in a subset of children with positive skin prick test results and elevated IgE levels [46]. Another study by Sistek et al showed the efficacy of the probiotics Lctbs rhamnosus and Bfdbm lactis in

A study by Finnish group used the same probiotic mixture with prebiotic. Kukkonen et al in a trial using probiotic mix (Lctbs rhamnosus GG, Lctbs rhamnosus LC705, Bfdbm breve Bb99; and Propionibacterium freudenreichii ssp. shermanii JS) and prebiotic galactooligosaccharides demonstrated that the prevention of atopic eczema in high-risk Finnish infants is possible by modulating the infant's gut microbiota with probiotics and prebiotics. Probiotic treatment compared with placebo reduced IgE-associated (atopic) diseases.

In 2009, in a study by Kuitunen et al 1223 Finnish mothers were randomized with infants at high risk for allergy to receive the same probiotic mixture (2 Lactobacilli, Bifidobacteria, and propionibacteria) or placebo during the last month of pregnancy and their infants to receive it from birth until age 6 months. Infants also received a prebiotic galacto-oligosaccharide or placebo. At 5 years, the cumulative incidence of allergic diseases (eczema, food allergy, allergic rhinitis, and asthma) and IgE sensitization were evaluated. Frequencies of allergic and IgE-associated allergic disease and sensitization in the probiotic and placebo groups were similar. However, less IgE-associated allergic disease occurred in cesarean-delivered children receiving probiotics**.** No allergy-preventive effect that extended to age 5 years was achieved with perinatal supplementation of probiotic bacteria to high-risk mothers and

Similarly; Abrahamsson et al could not confirm a preventive effect of probiotics (Lctbs reuteri ATCC 55730) on infant eczema in a recently published study. However, he observed that the treated infants had less IgE-associated eczema at 2 years. Moreover, skin prick test reactivity was also less common in the treated group than in the placebo group, but this

In conclusion; all of these studies taken together demonstrate that probiotics are might not be effective and /or therapeutic for all children with AD, but offer benefit in a subset of IgE-

Until now, several clinical studies have been published that have focused on the use of probiotics for therapy and primary prevention of atopic diseases. To date, the results of at

difference reached significance only for infants with allergic Swedish mothers [75].

Probiotic treatment also reduced eczema and atopic eczema [73].

children. It conferred protection only to cesarean-delivered children [74].

**3.2 Non-IgE-sensitized (non-atopic) eczema therapy and prevention** 

food-sensitized children [41].

sensitized children.


**Abbreviations**: Lctbs = Lactobacillus; Bfdbm = Bifidobacterium; LGG= Lactobacillus rhamnosus GG; ↑= increase in symptoms or negative effect; ↓= decrease in symptoms or positive effect; ↔ = No change in symptoms or no effect

Table 2. The various effects of different probiotic strains, referred in the chapter text, in atopic and non-atopic eczema are shown.

#### *Any difference for IgE-sensitized (atopic) vs. non-IgE-sensitized (non-atopic) eczema groups?*

A number of studies could only relate probiotic benefits to a certain subset of AD patients. In support of the efficacy of probiotics in IgE-sensitized children, some other studies also demonstrated comparable results as well. In brief: treatment with Lctbs rhamnosus for the first 2 years of life was associated with a significant reduction in the prevalence of any IgEassociated eczema by about a half [16]. Another study demonstrated that LGG alleviated atopic eczema/dermatitis syndrome symptoms in IgE-sensitized infants [28]. In foodsensitized atopic children, the efficacy of the probiotics such as Lctbs rhamnosus and Bfdbm lactis was demonstrated too [40].This effect was more pronounced in patients with a positive skin prick test and increased IgE levels.

Yet, some other studies failed to demonstrate that the severity and frequency of AD were decreased with the supplementation of probiotics, regardless of their IgE sensitization status. For instance; Boyle et al and others could not show any effect even for LGG in infants with AD [51]. A few meta-analyses also could not confirm that IgE sensitization was indeed a factor in determining the efficacy of probiotics in atopic children. However, the heterogeneity between studies may be attributable to probiotic strain-specific effects and other factors as well, meaning that some probiotic strains may still have a therapeutic role in eczema [13,14].

#### **3.1 IgE-sensitized (atopic) eczema therapy and prevention**

Recently published one of the largest studies by Viljanen et al to date compared LGG or a probiotic mix (LGG, Lctbs rhamnosus LC705, Bfdbm breve Bb99, and Propionibacterium freudenreichii ssp. shermanii JS) with placebo. In this study, 230 Finnish children with AD were treated for 4 weeks with LGG, a mixture of four probiotic strains or placebo. With

**Eczema (atopic dermatitis)**

Taylor et al 87 LGG or Lctbs acidophilus Atopic dermatitis (cow's

Boyle RJ et al 51 LGG Atopic dermatitis ↔ Gruber et al 89 LGG Atopic dermatitis ↔

Lee et al 95 Various Atopic dermatitis ↔ Brouwer et al 47 Lctbs rhamnosus Atopic dermatitis ↔

Fölster-Holst et al 90 LGG Atopic dermatitis ↔

Table 2. The various effects of different probiotic strains, referred in the chapter text, in

*Any difference for IgE-sensitized (atopic) vs. non-IgE-sensitized (non-atopic) eczema groups?*  A number of studies could only relate probiotic benefits to a certain subset of AD patients. In support of the efficacy of probiotics in IgE-sensitized children, some other studies also demonstrated comparable results as well. In brief: treatment with Lctbs rhamnosus for the first 2 years of life was associated with a significant reduction in the prevalence of any IgEassociated eczema by about a half [16]. Another study demonstrated that LGG alleviated atopic eczema/dermatitis syndrome symptoms in IgE-sensitized infants [28]. In foodsensitized atopic children, the efficacy of the probiotics such as Lctbs rhamnosus and Bfdbm lactis was demonstrated too [40].This effect was more pronounced in patients with a

**Abbreviations**: Lctbs = Lactobacillus; Bfdbm = Bifidobacterium; LGG= Lactobacillus rhamnosus GG; ↑= increase in symptoms or negative effect; ↓= decrease in symptoms or positive effect; ↔ = No change in

Yet, some other studies failed to demonstrate that the severity and frequency of AD were decreased with the supplementation of probiotics, regardless of their IgE sensitization status. For instance; Boyle et al and others could not show any effect even for LGG in infants with AD [51]. A few meta-analyses also could not confirm that IgE sensitization was indeed a factor in determining the efficacy of probiotics in atopic children. However, the heterogeneity between studies may be attributable to probiotic strain-specific effects and other factors as well,

Recently published one of the largest studies by Viljanen et al to date compared LGG or a probiotic mix (LGG, Lctbs rhamnosus LC705, Bfdbm breve Bb99, and Propionibacterium freudenreichii ssp. shermanii JS) with placebo. In this study, 230 Finnish children with AD were treated for 4 weeks with LGG, a mixture of four probiotic strains or placebo. With

meaning that some probiotic strains may still have a therapeutic role in eczema [13,14].

**3.1 IgE-sensitized (atopic) eczema therapy and prevention** 

Kopp et al 88 LGG Atopic dermatitis

Soh et al 91 Bfdbm longum + Lctbcs

Kuitunen et al 74 Lctbs+ Bfdbm+

atopic and non-atopic eczema are shown.

positive skin prick test and increased IgE levels.

symptoms or no effect

rhamnosus

**References Probiotic Species Type of Atopic Dermattis Outcome** 

(wheezing) ↔, (↑)

milk allergy) <sup>↔</sup>, (↑)

sensitization <sup>↔</sup>

Eczema and atopic

Propionibacteria Atopic dermatitis <sup>↔</sup>

supplementation with probiotics (LGG), Viljanen et al found significant improvement on the SCORAD index only in "IgE-sensitized -cow's milk -allergic- infants of the atopic eczema/dermatitis syndrome (AEDS). Only in the subgroup of IgE-sensitized children, did the LGG group show a greater reduction in SCORAD than the placebo group but this effect could have been due to a higher baseline score in this subgroup. There was no difference between the groups at the end of 4-week therapy and 4 weeks after therapy was discontinued. Contrary to what would be expected, improvement was seen 4 weeks after discontinuation of therapy rather than during treatment [28,72]. Rosenfeldt et al from Denmark in a study, 2 lyophilized probiotic Lctbs strains (lyophilized Lctbs rhamnosus 19070-2 and Lctbs reuteri DSM 122460) were given in combination for 6 weeks to 1- to 13 year-old (mean age, 5.2 years) children with AD. This study used 2 different Lctbs species in older children. A combination of these was beneficial in the management of AD. Statistically significant improvement in SCORAD score was seen only in a subset of children with positive skin prick test results and elevated IgE levels [46]. Another study by Sistek et al showed the efficacy of the probiotics Lctbs rhamnosus and Bfdbm lactis in food-sensitized children [41].

A study by Finnish group used the same probiotic mixture with prebiotic. Kukkonen et al in a trial using probiotic mix (Lctbs rhamnosus GG, Lctbs rhamnosus LC705, Bfdbm breve Bb99; and Propionibacterium freudenreichii ssp. shermanii JS) and prebiotic galactooligosaccharides demonstrated that the prevention of atopic eczema in high-risk Finnish infants is possible by modulating the infant's gut microbiota with probiotics and prebiotics. Probiotic treatment compared with placebo reduced IgE-associated (atopic) diseases. Probiotic treatment also reduced eczema and atopic eczema [73].

In 2009, in a study by Kuitunen et al 1223 Finnish mothers were randomized with infants at high risk for allergy to receive the same probiotic mixture (2 Lactobacilli, Bifidobacteria, and propionibacteria) or placebo during the last month of pregnancy and their infants to receive it from birth until age 6 months. Infants also received a prebiotic galacto-oligosaccharide or placebo. At 5 years, the cumulative incidence of allergic diseases (eczema, food allergy, allergic rhinitis, and asthma) and IgE sensitization were evaluated. Frequencies of allergic and IgE-associated allergic disease and sensitization in the probiotic and placebo groups were similar. However, less IgE-associated allergic disease occurred in cesarean-delivered children receiving probiotics**.** No allergy-preventive effect that extended to age 5 years was achieved with perinatal supplementation of probiotic bacteria to high-risk mothers and children. It conferred protection only to cesarean-delivered children [74].

Similarly; Abrahamsson et al could not confirm a preventive effect of probiotics (Lctbs reuteri ATCC 55730) on infant eczema in a recently published study. However, he observed that the treated infants had less IgE-associated eczema at 2 years. Moreover, skin prick test reactivity was also less common in the treated group than in the placebo group, but this difference reached significance only for infants with allergic Swedish mothers [75].

In conclusion; all of these studies taken together demonstrate that probiotics are might not be effective and /or therapeutic for all children with AD, but offer benefit in a subset of IgEsensitized children.

#### **3.2 Non-IgE-sensitized (non-atopic) eczema therapy and prevention**

Until now, several clinical studies have been published that have focused on the use of probiotics for therapy and primary prevention of atopic diseases. To date, the results of at

The Role of Probiotics in Atopic Dermatitis Prevention and Therapy 369

cutaneous symptoms of AD patients. Fifteen children with AD who had Bfdbm-deficient microflora were selected for this study. Eight subjects in the Bifidobacteria -administered group were given oral administration of lyophilized Bfdbm breve M-16V strain. In the Bifidobacteria -administered group, the proportion of Bfdbm in the fecal microflora was increased and the proportion of aerobic bacteria was decreased after 1 month of administration. Furthermore, significant improvement of allergic symptoms (in cutaneous symptom and total allergic scores) was also observed in the Bifidobacteria -administered group. The tendency of allergic symptom improvement was remarkable compared with the control group; however there was no correlation between changes in fecal microflora and

The Finnish study of Kalliomäki et al was the first report to describe that the frequency of AD in the probiotic group was half that of the placebo. This hallmark study demonstrated that administration of LGG for 1 month before and 6 months after birth to their infants was associated with a significant reduction in the cumulative incidence of eczema during the first 7 year of life. The effect of probiotics on preventing AD has been demonstrated in infants of Finnish pregnant mothers with a strong family history of eczema, allergic rhinitis or asthma. The frequency of developing AD in the offspring was significantly reduced by 2, 4, and 7 years, by 50%, 44%, and 36%; respectively. But there were no preventive effects on

Wickens et al studied a differential effect of 2 probiotics in the prevention of eczema and atopy. Infants receiving Lctbs rhamnosus had a significantly reduced risk of eczema, compared with placebo, but this was not the case for B animalis subsp lactis. In a doubleblind, randomized placebo-controlled trial of infants at risk of allergic disease, pregnant women were randomized to take Lctbs rhamnosus HN001, Bfdbm animalis subsp lactis strain HN019 or placebo daily from 35 weeks gestation until 6 months if breastfeeding, and their infants were randomized to receive the same treatment from birth to 2 years (n:474). Infants receiving Lctbs rhamnosus had a significantly reduced risk of eczema compared with placebo, but this was not the case for Bfdbm animalis subsp lactis. There was no significant effect of Lctbs rhamnosus or Bfdbm animalis subsp lactis on atopy. Lctbs rhamnosus (71.5%) was more likely than Bfdbm animalis subsp lactis (22.6%) to be present in the feces at 3 months, although detection rates were similar by 24 months. The authors found out that supplementation with Lctbs rhamnosus, but not Bfdbm animalis subsp lactis, substantially reduced the cumulative prevalence of eczema, but not atopy, by 2 years [81]. In a randomized double-blind study by Marschan et al, probiotic bacteria (Lctbs rhamnosus GG (ATCC 53103), Lctbs rhamnosus LC705, Bfdbm breve Bb99, and Propionibacterium freudenreichii ssp. Shermanii JS) or placebo were given for 1 month before delivery to mothers and for 6 months to infants with a family history of allergy. Infants receiving probiotic bacteria had higher plasma levels of CRP, total IgA, total IgE, and IL-10 than infants in the placebo group. Increased plasma CRP level at age 6 months was associated with a decreased risk of eczema and with a decreased risk of allergic disease at age 2 years, when adjusted with probiotic use. The association of CRP with a decreased risk of eczema at 2 years of age in allergy-prone children supports the view that chronic, low-grade inflammation protects from eczema. Probiotic-induced low-grade inflammation was characterized by elevation of IgE, IgA, and IL-10, the changes typically observed in helminth infection-associated induction of regulatory mechanisms [57] (please see the section:

atopic sensitization and onset of respiratory allergic diseases [16].

allergic symptoms [80].

mechanisms of probiotics` effects).

least 15 prospective preventive studies with different Lctbs or Bfdbm strains (or mixture) in children at high risk for allergic diseases have been published.

The first study in the literature by Isolauri et al analyzed a benefit of LGG in mild AD disease in 1997. They observed 27 exclusively breastfed infants (median age 4-6 months) with mild AD (median SCORAD score of 16), receiving extensively hydrolysed whey formula with (LGG or Bfdbm strain) or without probiotics (placebo) for 8 weeks. They showed a reduction in the SCORAD by 15 points (from 16 to 1) for the LGG and by 16 points (from 16 to 0) for the Bfdbm arm, as compared with a reduction of 2-6 points (from 16 to 13- 4) in the placebo arm. However, one month after therapy, SCORAD scores were comparable with those of placebo. Therefore, the probiotic effect was limited to acceleration of improvement in infants with mild disease [15]. The same investigators subsequently published 2 additional studies. One of these studies compared LGG with Bfdbm lactis Bb-12, both of which showed a significant improvement in SCORAD score over placebo. However, after 6 months, the median SCORAD score was zero in all groups, again suggesting that the effect is limited to rapid initiation of improvement [76]. The other study underlined the importance of viability for probiotic species. The use of heat inactivated LGG resulted in adverse gastrointestinal symptoms with diarrhea, and study recruitment was halted. They concluded that supplementation of infant formulas with viable but not heatinactivated LGG was found to be a potential approach for the management of atopic eczema and cow's milk allergy [77].

In an earlier study by Viljanen et al probiotics have been suggested to be useful in children with AEDS. In 2010, a study by Woo et al was performed to assess the clinical effect of Lctbs sakei supplementation in children with AEDS. In this study, children aged 2 to 10 years with AEDS with a minimum SCORAD score of 25 were randomized to receive either daily Lctbs sakei KCTC 10755BP or daily placebo supplementation for 12 weeks. At week 12, SCORAD total scores adjusted by pretreatment values were lower after probiotic treatment than after placebo treatment. There was a 31% improvement in mean disease activity with probiotic use compared with a 13% improvement with placebo use. Therefore significant differences in favor of probiotic treatment were also observed in proportions of patients achieving improvement of at least 30% and 50%. Interestingly, clinical improvement in this study was not just observed in the subgroup of IgE-sensitized children, contrary to Viljanen et al study, and it was regardless of IgE sensitization [56]. Weston et al from Australia published their experience with using Lctbs fermentum VRI-003 PCC for 8 weeks in 53 infants with AD. After 16 weeks the probiotic group had significant reduction of SCORAD scores while the placebo group did not. Lctbs fermentum caused a significant reduction in SCORAD scores. Although the change in SCORAD score from baseline in the probiotic group was significant, the difference between the probiotic and placebo groups did not reach significance by week 16 [78]. In a study by Hoang et al, they followed 14 cases of pediatric patients (ages of 8 months to 64 months) with a history of resistant eczema for a period of at least 6 months. All of these children received Lctbs rhamnosus cell lysate daily as an immunobiotic supplement. The results of this open label non-randomized clinical observation showed a substantial improvement in quality of life, skin symptoms and day- and nighttime irritation scores in children with the supplementation of Lctbs rhamnosus lysate. There were no intolerance or adverse reactions observed in these children. Lctbs rhamnosus cell lysate may thus be used as a safe and effective immunobiotic for the treatment and prevention of childhood eczema [79]. Bfdbm breve has been reported by Hattori et al to improve

least 15 prospective preventive studies with different Lctbs or Bfdbm strains (or mixture) in

The first study in the literature by Isolauri et al analyzed a benefit of LGG in mild AD disease in 1997. They observed 27 exclusively breastfed infants (median age 4-6 months) with mild AD (median SCORAD score of 16), receiving extensively hydrolysed whey formula with (LGG or Bfdbm strain) or without probiotics (placebo) for 8 weeks. They showed a reduction in the SCORAD by 15 points (from 16 to 1) for the LGG and by 16 points (from 16 to 0) for the Bfdbm arm, as compared with a reduction of 2-6 points (from 16 to 13- 4) in the placebo arm. However, one month after therapy, SCORAD scores were comparable with those of placebo. Therefore, the probiotic effect was limited to acceleration of improvement in infants with mild disease [15]. The same investigators subsequently published 2 additional studies. One of these studies compared LGG with Bfdbm lactis Bb-12, both of which showed a significant improvement in SCORAD score over placebo. However, after 6 months, the median SCORAD score was zero in all groups, again suggesting that the effect is limited to rapid initiation of improvement [76]. The other study underlined the importance of viability for probiotic species. The use of heat inactivated LGG resulted in adverse gastrointestinal symptoms with diarrhea, and study recruitment was halted. They concluded that supplementation of infant formulas with viable but not heatinactivated LGG was found to be a potential approach for the management of atopic eczema

In an earlier study by Viljanen et al probiotics have been suggested to be useful in children with AEDS. In 2010, a study by Woo et al was performed to assess the clinical effect of Lctbs sakei supplementation in children with AEDS. In this study, children aged 2 to 10 years with AEDS with a minimum SCORAD score of 25 were randomized to receive either daily Lctbs sakei KCTC 10755BP or daily placebo supplementation for 12 weeks. At week 12, SCORAD total scores adjusted by pretreatment values were lower after probiotic treatment than after placebo treatment. There was a 31% improvement in mean disease activity with probiotic use compared with a 13% improvement with placebo use. Therefore significant differences in favor of probiotic treatment were also observed in proportions of patients achieving improvement of at least 30% and 50%. Interestingly, clinical improvement in this study was not just observed in the subgroup of IgE-sensitized children, contrary to Viljanen et al study, and it was regardless of IgE sensitization [56]. Weston et al from Australia published their experience with using Lctbs fermentum VRI-003 PCC for 8 weeks in 53 infants with AD. After 16 weeks the probiotic group had significant reduction of SCORAD scores while the placebo group did not. Lctbs fermentum caused a significant reduction in SCORAD scores. Although the change in SCORAD score from baseline in the probiotic group was significant, the difference between the probiotic and placebo groups did not reach significance by week 16 [78]. In a study by Hoang et al, they followed 14 cases of pediatric patients (ages of 8 months to 64 months) with a history of resistant eczema for a period of at least 6 months. All of these children received Lctbs rhamnosus cell lysate daily as an immunobiotic supplement. The results of this open label non-randomized clinical observation showed a substantial improvement in quality of life, skin symptoms and day- and nighttime irritation scores in children with the supplementation of Lctbs rhamnosus lysate. There were no intolerance or adverse reactions observed in these children. Lctbs rhamnosus cell lysate may thus be used as a safe and effective immunobiotic for the treatment and prevention of childhood eczema [79]. Bfdbm breve has been reported by Hattori et al to improve

children at high risk for allergic diseases have been published.

and cow's milk allergy [77].

cutaneous symptoms of AD patients. Fifteen children with AD who had Bfdbm-deficient microflora were selected for this study. Eight subjects in the Bifidobacteria -administered group were given oral administration of lyophilized Bfdbm breve M-16V strain. In the Bifidobacteria -administered group, the proportion of Bfdbm in the fecal microflora was increased and the proportion of aerobic bacteria was decreased after 1 month of administration. Furthermore, significant improvement of allergic symptoms (in cutaneous symptom and total allergic scores) was also observed in the Bifidobacteria -administered group. The tendency of allergic symptom improvement was remarkable compared with the control group; however there was no correlation between changes in fecal microflora and allergic symptoms [80].

The Finnish study of Kalliomäki et al was the first report to describe that the frequency of AD in the probiotic group was half that of the placebo. This hallmark study demonstrated that administration of LGG for 1 month before and 6 months after birth to their infants was associated with a significant reduction in the cumulative incidence of eczema during the first 7 year of life. The effect of probiotics on preventing AD has been demonstrated in infants of Finnish pregnant mothers with a strong family history of eczema, allergic rhinitis or asthma. The frequency of developing AD in the offspring was significantly reduced by 2, 4, and 7 years, by 50%, 44%, and 36%; respectively. But there were no preventive effects on atopic sensitization and onset of respiratory allergic diseases [16].

Wickens et al studied a differential effect of 2 probiotics in the prevention of eczema and atopy. Infants receiving Lctbs rhamnosus had a significantly reduced risk of eczema, compared with placebo, but this was not the case for B animalis subsp lactis. In a doubleblind, randomized placebo-controlled trial of infants at risk of allergic disease, pregnant women were randomized to take Lctbs rhamnosus HN001, Bfdbm animalis subsp lactis strain HN019 or placebo daily from 35 weeks gestation until 6 months if breastfeeding, and their infants were randomized to receive the same treatment from birth to 2 years (n:474). Infants receiving Lctbs rhamnosus had a significantly reduced risk of eczema compared with placebo, but this was not the case for Bfdbm animalis subsp lactis. There was no significant effect of Lctbs rhamnosus or Bfdbm animalis subsp lactis on atopy. Lctbs rhamnosus (71.5%) was more likely than Bfdbm animalis subsp lactis (22.6%) to be present in the feces at 3 months, although detection rates were similar by 24 months. The authors found out that supplementation with Lctbs rhamnosus, but not Bfdbm animalis subsp lactis, substantially reduced the cumulative prevalence of eczema, but not atopy, by 2 years [81].

In a randomized double-blind study by Marschan et al, probiotic bacteria (Lctbs rhamnosus GG (ATCC 53103), Lctbs rhamnosus LC705, Bfdbm breve Bb99, and Propionibacterium freudenreichii ssp. Shermanii JS) or placebo were given for 1 month before delivery to mothers and for 6 months to infants with a family history of allergy. Infants receiving probiotic bacteria had higher plasma levels of CRP, total IgA, total IgE, and IL-10 than infants in the placebo group. Increased plasma CRP level at age 6 months was associated with a decreased risk of eczema and with a decreased risk of allergic disease at age 2 years, when adjusted with probiotic use. The association of CRP with a decreased risk of eczema at 2 years of age in allergy-prone children supports the view that chronic, low-grade inflammation protects from eczema. Probiotic-induced low-grade inflammation was characterized by elevation of IgE, IgA, and IL-10, the changes typically observed in helminth infection-associated induction of regulatory mechanisms [57] (please see the section: mechanisms of probiotics` effects).

The Role of Probiotics in Atopic Dermatitis Prevention and Therapy 371

Oral administration of probiotic Escherichia coli after birth in the early postnatal period by Lodinova-Zadnikova et al reduced frequency of serum specific IgE allergies later in life

Gerasimov et al conducted a study to assess the clinical efficacy and impact of Lctbs acidophilus DDS-1, Bfdbm lactis UABLA-12 with fructo-oligosaccharide on peripheral blood lymphocyte subsets in preschool children with moderate-to-severe AD. In a randomized, double-blind, placebo-controlled, prospective trial of 90 children aged 1-3 years with moderate-to-severe AD who were treated with a mixture of probiotics with fructooligosaccharide for 8 weeks versus placebo. At the final visit, the percentage significant decrease in SCORAD was 33.7% in the probiotic group compared with 19.4% in the placebo group. Children receiving probiotic showed a greater decrease in the mean SCORAD score than did children from the placebo group at week 8. The administration of a probiotic mixture and fructo-oligosaccharide was associated with significant clinical improvement in children with AD, with corresponding lymphocyte subset changes in peripheral blood [68]. In conclusion; here probiotics were more likely to be effective in treating moderately severe AD as well as mild atopic disease. Although not every study result above was significant, the effect of probiotics did not seem to be greater just in the IgE-sensitized group than in the non–IgE-sensitized group. Nevertheless, there have been several reports in the literature

showing no effect of probiotics, which are being discussed the section below.

for primary prevention must be exercised with caution [87].

**3.3 No therapeutic or preventive effect of probiotics in AD regardless of IgE** 

It is striking that the proportion of children with AD and allergic sensitization such as in the study of Taylor and Huurre et al was significantly higher in the probiotic group [86]. In Taylor et al's trial probiotic supplementation postnatally failed to reduce the risk of AD and increased the risk of allergen sensitization in high-risk children. Newborns of women with allergy (n:231) received either Lctbs acidophilus (LAVRI-A1) or placebo daily for the first 6 months of life. Children were assessed for AD and other symptoms at 6 and 12 months and had allergen skin prick tests at 12 months of age. At 6 and 12 months, AD rates were similar in the probiotic and placebo groups. At 12 months, the rate of sensitization was significantly higher in the probiotic group. The presence of culturable Lactobacilli or Bfdbm in stools in the first month of life was not associated with the risk of subsequent sensitization or disease; however, the presence of Lctbs at 6 months of age was associated with increased risk of subsequent cow's milk sensitization. Early probiotic supplementation with Lctbs acidophilus did not reduce the risk of AD in high-risk infants and was associated with increased allergen sensitization in infants receiving supplements. There were 3 major differences between Taylor's study and the others. The type of probiotic product (Lctbs acidophilus), the supplementation period (1 year) as well as the timing of the introduction of the probiotic were different*.* Taylor et al administered the probiotic supplement postnatally, while other studies administered probiotics before and after birth. Prenatal supplementation may prove to be crucial for the preventive benefit of probiotics in this disorder. The data from the Taylor et al's study point in the same direction regarding allergic sensitization, also suggesting that the use of probiotics

Similarly, a randomized, double-blind, placebo-controlled prospective trial by Kopp et al of probiotics for primary prevention did show no clinical effects of LGG supplementation. 105 pregnant women from families with ≥1 member (mother, father, or child) with an atopic

(after 10 and 20 years) [85].

**sensitization** 

In the PandA study of Niers et al administered a mixture of probiotic bacteria (Bfdbm bifidum W23, Bfdbm lactis W52, and Lactococcus lactis W58; Ecologic Panda) for 6 week prenatally to mothers of high-risk children and to their offspring for the first 12 months of life. Although cumulative incidence of atopic eczema and IgE levels were similar in both treated and placebo groups, the parental reported eczema was significantly lower during the first 3 months of life in infants receiving probiotics. This particular combination of probiotic bacteria showed a preventive effect on the incidence of eczema in high-risk children, which seems to be sustained during the first 2 years of life. In addition to previous studies, the preventive effect appeared to be established within the first 3 months of life in this study [82].

In a trial by Kim et al, 112 pregnant women with a family history of allergic diseases received a mixture of Bfdbm bifidum BGN4, Bfdbm lactis AD011, and Lctbs acidophilus AD031, starting at 4-8 wks before delivery and continuing until 6 months after delivery. The cumulative incidence of eczema during the first 12 months was reduced significantly in probiotic group; however, there was no difference in serum total IgE level or the sensitization against food allergens between the two groups. Prenatal and postnatal supplementation with a mixture of probiotics is an effective approach in preventing the development of eczema in infants at high risk of allergy during the first year of life [83].

In a randomized, double-blind trial by Dotterud et al, probiotics was given in pregnant women to prevent allergic disease. In this study children from a nonselected maternal population, women received probiotic milk or placebo from 36 weeks of gestation to 3 months postnatally during breastfeeding. The probiotic milk contained Lctbs rhamnosus GG, Lctbs acidophilus La–5 and Bfdbm animalis subsp. lactis Bb-12. At 2 years of age, all children were assessed for atopic sensitization, AD, asthma and allergic rhinoconjunctivitis. Probiotics given to nonselected mothers reduced the cumulative incidence of AD, but had no effect on asthma or atopic sensitization [84].

Böttcher et al's study demonstrated that Lctbs reuteri supplementation during pregnancy associated with reduced risk of sensitization during infancy. Swedish pregnant women were treated with Lctbs reuteri (n:54) or placebo (n:55) from gestational week 36 until delivery. The infants were followed prospectively for 2 years regarding development of eczema and sensitization as defined by a positive skin prick test and/or circulating allergen-specific IgE antibodies at 6, 12, and 24 months of age [52].

Of note, another recently published Swedish study demonstrated that administration of Lctbs casei F19 during weaning significantly reduced the incidence of eczema, indicating that proper timing of the probiotic intervention is a critical factor. This study also supports the notion that there is more than a single window of opportunity to manage allergic diseases. This study evaluated the effects of feeding with Lctbs F19 during weaning period on the incidence of eczema and Th1/Th2 balance. In this intervention trial by West et al, infants were fed cereals with (n:89) or without Lctbs F19 (n:90) from 4-13 months of age. The cumulative incidence of eczema at 13 months was 11% and 22% in the probiotic and placebo groups, respectively (p:<0.05). At 13 months of age, the IFN-γ / IL-4 mRNA ratio was significantly higher in the probiotic compared with the placebo group. The higher Th1/Th2 ratio in the probiotic compared with the placebo group suggests enhancing effects of Lctbs F19 on the T cell-mediated immune response. In contrast, there were no differences between groups in serum IgE concentrations. As a result, feeding Lctbs F19 during weaning could be an effective tool in the prevention of early manifestation of allergy such as eczema [40].

In the PandA study of Niers et al administered a mixture of probiotic bacteria (Bfdbm bifidum W23, Bfdbm lactis W52, and Lactococcus lactis W58; Ecologic Panda) for 6 week prenatally to mothers of high-risk children and to their offspring for the first 12 months of life. Although cumulative incidence of atopic eczema and IgE levels were similar in both treated and placebo groups, the parental reported eczema was significantly lower during the first 3 months of life in infants receiving probiotics. This particular combination of probiotic bacteria showed a preventive effect on the incidence of eczema in high-risk children, which seems to be sustained during the first 2 years of life. In addition to previous studies, the preventive effect appeared to be established within the first 3 months of life in

In a trial by Kim et al, 112 pregnant women with a family history of allergic diseases received a mixture of Bfdbm bifidum BGN4, Bfdbm lactis AD011, and Lctbs acidophilus AD031, starting at 4-8 wks before delivery and continuing until 6 months after delivery. The cumulative incidence of eczema during the first 12 months was reduced significantly in probiotic group; however, there was no difference in serum total IgE level or the sensitization against food allergens between the two groups. Prenatal and postnatal supplementation with a mixture of probiotics is an effective approach in preventing the development of eczema in infants at high risk of allergy during the first year of life [83]. In a randomized, double-blind trial by Dotterud et al, probiotics was given in pregnant women to prevent allergic disease. In this study children from a nonselected maternal population, women received probiotic milk or placebo from 36 weeks of gestation to 3 months postnatally during breastfeeding. The probiotic milk contained Lctbs rhamnosus GG, Lctbs acidophilus La–5 and Bfdbm animalis subsp. lactis Bb-12. At 2 years of age, all children were assessed for atopic sensitization, AD, asthma and allergic rhinoconjunctivitis. Probiotics given to nonselected mothers reduced the cumulative incidence of AD, but had

Böttcher et al's study demonstrated that Lctbs reuteri supplementation during pregnancy associated with reduced risk of sensitization during infancy. Swedish pregnant women were treated with Lctbs reuteri (n:54) or placebo (n:55) from gestational week 36 until delivery. The infants were followed prospectively for 2 years regarding development of eczema and sensitization as defined by a positive skin prick test and/or circulating allergen-specific IgE

Of note, another recently published Swedish study demonstrated that administration of Lctbs casei F19 during weaning significantly reduced the incidence of eczema, indicating that proper timing of the probiotic intervention is a critical factor. This study also supports the notion that there is more than a single window of opportunity to manage allergic diseases. This study evaluated the effects of feeding with Lctbs F19 during weaning period on the incidence of eczema and Th1/Th2 balance. In this intervention trial by West et al, infants were fed cereals with (n:89) or without Lctbs F19 (n:90) from 4-13 months of age. The cumulative incidence of eczema at 13 months was 11% and 22% in the probiotic and placebo groups, respectively (p:<0.05). At 13 months of age, the IFN-γ / IL-4 mRNA ratio was significantly higher in the probiotic compared with the placebo group. The higher Th1/Th2 ratio in the probiotic compared with the placebo group suggests enhancing effects of Lctbs F19 on the T cell-mediated immune response. In contrast, there were no differences between groups in serum IgE concentrations. As a result, feeding Lctbs F19 during weaning could be an effective tool in the prevention of early manifestation of allergy such as eczema [40].

this study [82].

no effect on asthma or atopic sensitization [84].

antibodies at 6, 12, and 24 months of age [52].

Oral administration of probiotic Escherichia coli after birth in the early postnatal period by Lodinova-Zadnikova et al reduced frequency of serum specific IgE allergies later in life (after 10 and 20 years) [85].

Gerasimov et al conducted a study to assess the clinical efficacy and impact of Lctbs acidophilus DDS-1, Bfdbm lactis UABLA-12 with fructo-oligosaccharide on peripheral blood lymphocyte subsets in preschool children with moderate-to-severe AD. In a randomized, double-blind, placebo-controlled, prospective trial of 90 children aged 1-3 years with moderate-to-severe AD who were treated with a mixture of probiotics with fructooligosaccharide for 8 weeks versus placebo. At the final visit, the percentage significant decrease in SCORAD was 33.7% in the probiotic group compared with 19.4% in the placebo group. Children receiving probiotic showed a greater decrease in the mean SCORAD score than did children from the placebo group at week 8. The administration of a probiotic mixture and fructo-oligosaccharide was associated with significant clinical improvement in children with AD, with corresponding lymphocyte subset changes in peripheral blood [68].

In conclusion; here probiotics were more likely to be effective in treating moderately severe AD as well as mild atopic disease. Although not every study result above was significant, the effect of probiotics did not seem to be greater just in the IgE-sensitized group than in the non–IgE-sensitized group. Nevertheless, there have been several reports in the literature showing no effect of probiotics, which are being discussed the section below.

#### **3.3 No therapeutic or preventive effect of probiotics in AD regardless of IgE sensitization**

It is striking that the proportion of children with AD and allergic sensitization such as in the study of Taylor and Huurre et al was significantly higher in the probiotic group [86]. In Taylor et al's trial probiotic supplementation postnatally failed to reduce the risk of AD and increased the risk of allergen sensitization in high-risk children. Newborns of women with allergy (n:231) received either Lctbs acidophilus (LAVRI-A1) or placebo daily for the first 6 months of life. Children were assessed for AD and other symptoms at 6 and 12 months and had allergen skin prick tests at 12 months of age. At 6 and 12 months, AD rates were similar in the probiotic and placebo groups. At 12 months, the rate of sensitization was significantly higher in the probiotic group. The presence of culturable Lactobacilli or Bfdbm in stools in the first month of life was not associated with the risk of subsequent sensitization or disease; however, the presence of Lctbs at 6 months of age was associated with increased risk of subsequent cow's milk sensitization. Early probiotic supplementation with Lctbs acidophilus did not reduce the risk of AD in high-risk infants and was associated with increased allergen sensitization in infants receiving supplements. There were 3 major differences between Taylor's study and the others. The type of probiotic product (Lctbs acidophilus), the supplementation period (1 year) as well as the timing of the introduction of the probiotic were different*.* Taylor et al administered the probiotic supplement postnatally, while other studies administered probiotics before and after birth. Prenatal supplementation may prove to be crucial for the preventive benefit of probiotics in this disorder. The data from the Taylor et al's study point in the same direction regarding allergic sensitization, also suggesting that the use of probiotics for primary prevention must be exercised with caution [87].

Similarly, a randomized, double-blind, placebo-controlled prospective trial by Kopp et al of probiotics for primary prevention did show no clinical effects of LGG supplementation. 105 pregnant women from families with ≥1 member (mother, father, or child) with an atopic

The Role of Probiotics in Atopic Dermatitis Prevention and Therapy 373

of Kalliomäki et al and continued to supplement LGG for 3 months after birth to the breastfeeding mothers and the following 3 months only to the neonates. This modification was made to achieve a more consistent probiotic delivery. Second, Finnish mothers received supplementation during the last 4 weeks of pregnancy, whereas pregnant women in this population commenced with LGG or placebo for 4 to 6 weeks. They extended the prenatal supplementation period, because a 4-week period is thought to possibly be too short for suspected in utero effects of LGG supplementation. Also, population in this study by Kopp et al was being of higher risk compared with the Finnish population, which might account for the differing results. And more infants with older siblings were recruited compared with the Finnish study. Lastly, the Finnish and German

A metaanalysis of the evidence from randomized controlled trials by Betsi et al on probiotics for the treatment or prevention of AD: the results of 13 relevant randomized (placebo) controlled trials were reviewed: 10 of which evaluated probiotics as treatment and 3 for prevention of AD. Four RCTs suggested that there was a statistically significant decrease in SCORAD after probiotic administration to infants or children with AD for 1 or 2 months compared with that after placebo. While in two RCTs SCORAD was significantly reduced after treatment with Lactobacilli only in children with IgE-associated AD. In three RCTs, the change in SCORAD was not statistically significant between probiotic- and placebo-treated children, although in one of these trials SCORAD was significantly lower after probiotic than with placebo treatment in food-sensitized children. As a result; probiotics, especially Lctbs rhamnosus GG, seem to be effective for the prevention of AD and they were also found to reduce the severity of AD in approximately half of the RCTs evaluated [53]. Likewise, Zhu et al did a metaanalysis of lactic acid bacteria as probiotics for the primary prevention of infantile eczema. The data from this metaanalysis suggested that lactic acid probiotics combined with other probiotics play a role in the prevention of infantile eczema. Conversely, another recent meta-analysis did not show a therapeutic difference among children receiving probiotics. This analysis excluded six of the ten studies published,

In a review article; atopic disease and / or food hypersensitivity outcomes were assessed by Osborn et al in 6 studies enrolling 2080 infants, but outcomes for only 1549 infants were reported. Meta-analysis of five studies reporting the outcomes of 1477 infants found a significant reduction in infantile eczema. When the analysis was restricted to studies reporting atopic eczema (confirmed by skin prick test or specific IgE), the findings were no longer significant. All studies reporting significant benefits used probiotic supplements containing Lctbs rhamnosus and enrolled infants at high risk of allergy [93]. Another recent meta-analysis suggested that probiotics may benefit children and infants with the disorder. The metaanalysis identified 10 randomized, controlled trials. A significant overall benefit was demonstrated after the use of probiotics, resulting in a reduction of the SCORAD scores compared to placebo. LGG appeared to be more effective than other probiotic preparations and children with more severe disease were more likely to benefit from the use of probiotics [94]. This remarkable meta-analysis was done to determine whether probiotics are efficacious in treating AD and to explore whether type of probiotic used, duration of therapy, patient age, severity of disease, and IgE sensitization are factors in determining

populations are of different genetic background.

making the validity of the report questionable [92].

**4. Recent metaanalyses and reviews from literature** 

disease were randomly assigned to receive either the probiotic LGG or pacebo. The supplementation period started 4 to 6 weeks before expected delivery, followed by a postnatal period of 6 months. The primary end point was the occurrence of AD at the age of 2 years. Secondary outcomes were severity of AD, recurrent episodes of wheezing bronchitis, and allergic sensitization at the age of 2 years. Notably, children with recurrent (≥5) episodes of wheezing bronchitis were more frequent in the LGG group (26%), as compared with the placebo group (9%). As a result, supplementation with LGG during pregnancy and early infancy neither reduced the incidence of AD nor altered the severity of AD in affected children but was associated with an increased rate of recurrent episodes of wheezing bronchitis. No difference was observed between both groups in total Ig E concentrations or numbers of specific sensitization to inhalant allergens [88].

Furthermore; prenatal probiotic LGG treatment during pregnancy was not associated with reduced risk of eczema or IgE-associated eczema in a randomized controlled trial by Boyle RJ [51]. In a recent study, 250 pregnant women were recruited carrying infants at high risk of allergic disease to a randomized controlled trial of probiotic supplementation (LGG) from 36 weeks gestation until delivery. Gruber et al's study also did not show any effect for LGG in infants with AD regardless of their IgE sensitization status [89].

However, a study from the Netherlands by Brouwer et al and another study from Germany by Folster-Holst et al showed no effect of L*GG* in infants with AD regardless of their IgE sensitization status. In a study conducted by Brouwer et al, after 4–6 weeks of baseline and double-blind, placebo-controlled challenges for diagnosis of cow's milk allergy, infants less than 5 months old with AD received a hydrolysed whey-based formula as placebo (n:17), or supplemented with either Lctbs rhamnosus (n:17) or LGG (n:16) for 3 months. No statistically significant effects of probiotic supplementation on SCORAD, sensitization, inflammatory parameters or cytokine production between groups were found. No clinical or immunological effect of the probiotic bacteria used in infants with AD [47]. A similar prospective study by Fölster**-**Holst et al was performed to reassess the efficacy of orally administered LGG in infants with AD. In a randomized, double-blind, placebo-controlled study, 54 infants aged 1–55 months with moderate to severe AD were randomized to receive LGG or to placebo during an 8-week intervention phase. At the end of treatment there were no significant differences between the groups with respect to clinical symptoms (SCORAD, pruritus, and sleep loss), immunological parameters, or health-related quality of life of the parents [90]. Additionally; Soh et al in a clinical trial involving 253 infants with a family history of allergic disease utilized probiotic supplementation (Bfdbm longum + Lctbs rhamnosus) in the first 6 months of life in Asian infants at risk and evaluated the effects on eczema and atopic sensitization at the age of 1 year. Early life administration of a cow's milk formula supplemented with probiotics showed no effect on prevention of eczema or allergen sensitization in the first year of life in Asian infants at risk of allergic disease [91]. In conclusion; LGG was mostly used probiotic species in these studies. Firstly used by Kalliomaki et al [16] with a success however, other groups including Brouwer, Boyle, Kopp, Gruber, and Fölster -Holst et al [47,51,87,88,90] could not demonstrate any benefit in AD. For instance: Kopp et al have shown that the probiotic LGG has no preventive effect on the development or the severity of AD at the age of 2 years in a German population of infants at high risk. Instead, there was a significantly higher risk of ≥5 episodes with wheezing

bronchitis during the first 2 years in the LGG group, as compared with placebo. There were several methodological differences between these studies: Kopp et al adapted the protocol

disease were randomly assigned to receive either the probiotic LGG or pacebo. The supplementation period started 4 to 6 weeks before expected delivery, followed by a postnatal period of 6 months. The primary end point was the occurrence of AD at the age of 2 years. Secondary outcomes were severity of AD, recurrent episodes of wheezing bronchitis, and allergic sensitization at the age of 2 years. Notably, children with recurrent (≥5) episodes of wheezing bronchitis were more frequent in the LGG group (26%), as compared with the placebo group (9%). As a result, supplementation with LGG during pregnancy and early infancy neither reduced the incidence of AD nor altered the severity of AD in affected children but was associated with an increased rate of recurrent episodes of wheezing bronchitis. No difference was observed between both groups in total Ig E

Furthermore; prenatal probiotic LGG treatment during pregnancy was not associated with reduced risk of eczema or IgE-associated eczema in a randomized controlled trial by Boyle RJ [51]. In a recent study, 250 pregnant women were recruited carrying infants at high risk of allergic disease to a randomized controlled trial of probiotic supplementation (LGG) from 36 weeks gestation until delivery. Gruber et al's study also did not show any effect for LGG

However, a study from the Netherlands by Brouwer et al and another study from Germany by Folster-Holst et al showed no effect of L*GG* in infants with AD regardless of their IgE sensitization status. In a study conducted by Brouwer et al, after 4–6 weeks of baseline and double-blind, placebo-controlled challenges for diagnosis of cow's milk allergy, infants less than 5 months old with AD received a hydrolysed whey-based formula as placebo (n:17), or supplemented with either Lctbs rhamnosus (n:17) or LGG (n:16) for 3 months. No statistically significant effects of probiotic supplementation on SCORAD, sensitization, inflammatory parameters or cytokine production between groups were found. No clinical or immunological effect of the probiotic bacteria used in infants with AD [47]. A similar prospective study by Fölster**-**Holst et al was performed to reassess the efficacy of orally administered LGG in infants with AD. In a randomized, double-blind, placebo-controlled study, 54 infants aged 1–55 months with moderate to severe AD were randomized to receive LGG or to placebo during an 8-week intervention phase. At the end of treatment there were no significant differences between the groups with respect to clinical symptoms (SCORAD, pruritus, and sleep loss), immunological parameters, or health-related quality of life of the parents [90]. Additionally; Soh et al in a clinical trial involving 253 infants with a family history of allergic disease utilized probiotic supplementation (Bfdbm longum + Lctbs rhamnosus) in the first 6 months of life in Asian infants at risk and evaluated the effects on eczema and atopic sensitization at the age of 1 year. Early life administration of a cow's milk formula supplemented with probiotics showed no effect on prevention of eczema or allergen sensitization in the first year of life in Asian infants at risk of allergic disease [91]. In conclusion; LGG was mostly used probiotic species in these studies. Firstly used by Kalliomaki et al [16] with a success however, other groups including Brouwer, Boyle, Kopp, Gruber, and Fölster -Holst et al [47,51,87,88,90] could not demonstrate any benefit in AD. For instance: Kopp et al have shown that the probiotic LGG has no preventive effect on the development or the severity of AD at the age of 2 years in a German population of infants at high risk. Instead, there was a significantly higher risk of ≥5 episodes with wheezing bronchitis during the first 2 years in the LGG group, as compared with placebo. There were several methodological differences between these studies: Kopp et al adapted the protocol

concentrations or numbers of specific sensitization to inhalant allergens [88].

in infants with AD regardless of their IgE sensitization status [89].

of Kalliomäki et al and continued to supplement LGG for 3 months after birth to the breastfeeding mothers and the following 3 months only to the neonates. This modification was made to achieve a more consistent probiotic delivery. Second, Finnish mothers received supplementation during the last 4 weeks of pregnancy, whereas pregnant women in this population commenced with LGG or placebo for 4 to 6 weeks. They extended the prenatal supplementation period, because a 4-week period is thought to possibly be too short for suspected in utero effects of LGG supplementation. Also, population in this study by Kopp et al was being of higher risk compared with the Finnish population, which might account for the differing results. And more infants with older siblings were recruited compared with the Finnish study. Lastly, the Finnish and German populations are of different genetic background.

#### **4. Recent metaanalyses and reviews from literature**

A metaanalysis of the evidence from randomized controlled trials by Betsi et al on probiotics for the treatment or prevention of AD: the results of 13 relevant randomized (placebo) controlled trials were reviewed: 10 of which evaluated probiotics as treatment and 3 for prevention of AD. Four RCTs suggested that there was a statistically significant decrease in SCORAD after probiotic administration to infants or children with AD for 1 or 2 months compared with that after placebo. While in two RCTs SCORAD was significantly reduced after treatment with Lactobacilli only in children with IgE-associated AD. In three RCTs, the change in SCORAD was not statistically significant between probiotic- and placebo-treated children, although in one of these trials SCORAD was significantly lower after probiotic than with placebo treatment in food-sensitized children. As a result; probiotics, especially Lctbs rhamnosus GG, seem to be effective for the prevention of AD and they were also found to reduce the severity of AD in approximately half of the RCTs evaluated [53]. Likewise, Zhu et al did a metaanalysis of lactic acid bacteria as probiotics for the primary prevention of infantile eczema. The data from this metaanalysis suggested that lactic acid probiotics combined with other probiotics play a role in the prevention of infantile eczema. Conversely, another recent meta-analysis did not show a therapeutic difference among children receiving probiotics. This analysis excluded six of the ten studies published, making the validity of the report questionable [92].

In a review article; atopic disease and / or food hypersensitivity outcomes were assessed by Osborn et al in 6 studies enrolling 2080 infants, but outcomes for only 1549 infants were reported. Meta-analysis of five studies reporting the outcomes of 1477 infants found a significant reduction in infantile eczema. When the analysis was restricted to studies reporting atopic eczema (confirmed by skin prick test or specific IgE), the findings were no longer significant. All studies reporting significant benefits used probiotic supplements containing Lctbs rhamnosus and enrolled infants at high risk of allergy [93]. Another recent meta-analysis suggested that probiotics may benefit children and infants with the disorder. The metaanalysis identified 10 randomized, controlled trials. A significant overall benefit was demonstrated after the use of probiotics, resulting in a reduction of the SCORAD scores compared to placebo. LGG appeared to be more effective than other probiotic preparations and children with more severe disease were more likely to benefit from the use of probiotics [94]. This remarkable meta-analysis was done to determine whether probiotics are efficacious in treating AD and to explore whether type of probiotic used, duration of therapy, patient age, severity of disease, and IgE sensitization are factors in determining

The Role of Probiotics in Atopic Dermatitis Prevention and Therapy 375

only a few weeks in the antenatal period alone would account for such significant differences in study outcomes, although this remains a possibility. **Thirdly (**intervention methods**)**, in most studies all babies received the supplement directly, regardless of feeding method, whereas in the Finnish and other studies, the mother took the probiotics if babies were breastfed. Therefore, the Finnish probiotic group and others included breast-fed infants who did not receive probiotics directly in addition to the bottle-fed infants who received probiotics for 6 months. **Fourthly** (postnatal assessment time), some researchers assessed clinical outcomes at 12 months of age, whereas the effects on AD in the Finnish or other studies were reported at 2, 4 and subsequently at 7 years of age. AD typically begins in the first year of life, and it is possible that more children could become affected in their second year of life. And in young infants, the immune system is still developing. There is still a possibility to direct it toward tolerance. In older children, the allergic phenotype is already established, and here one may only be able to relieve the symptoms. **Fifthly** (atopy risk and host factors of targeted group), some studies were performed in high-risk population all had maternal allergic disease confirmed by SPT, whereas the Finnish and other population included children with maternal, paternal, or sibling allergy. This may lead to some population being of slightly higher risk, compared with the Finnish and other population at the same age. Explanations for varied study results include host factors such as genetic susceptibility, environmental factors such as geographic region and diet [98]. Genotyping of study patients in relation to different genes predisposing to allergic diseases may help to find patients that might especially benefit from probiotic intervention. For example, 2 independent mutations in the gene encoding the epidermal protein filaggrin have been shown to be strong predisposing factors for childhood eczema [99]. Of note, these same mutations have recently been demonstrated to be associated not only with eczema-associated asthma susceptibility but also with asthma severity independent of eczema status. More generally, any means to better stratify or select defined subpopulations of subjects (e.g. patients with food allergy as a separate group) would help in clarifying the potency and limits of probiotic interventions against atopic diseases. **Sixthly (**other methodological set-up**),** there may be still due to differences in the clinical and methodological set-up (additional treatments such as topical treatment or feeding hydrolyzed infant formulae and importantly, different probiotic preparations or formulations or combinations). Other differences include age (6–18 months) of the studied children and an intervention period (16 weeks) of time. **Seventhly (**nomenclature of the disease**),** to date, randomized clinical trials of probiotics in allergic diseases have mostly focused on children with eczema and atopic eczema. The definitions of the disease have recently been revised by an international expert group [17-19]. In many of the studies published before the revision of the nomenclature, different definitions have been used, making direct comparisons between the studies difficult. The severity of AD at the start of an intervention may influence the

Probiotics available as food ingredients or dietary supplements that contain microorganisms have been used extensively in food processing for years, with a long history of safety and no adverse effects on metabolism. However, when considering the safety of probiotics, potential adverse effects include systemic infections, altered metabolism, and gene transfer [100]. A recent report has identified Lctbs septicemia in 2 children with short bowel syndrome who were receiving LGG supplementation for control of bacterial overgrowth

outcome as well, as you imagine.

**6. Safety** 

efficacy. For this meta-analysis of randomized controlled trials describing the efficacy of probiotics in AD, a comprehensive search was performed of databases through January 2008. Eleven studies were identified, and data from 10 studies (n: ≥678) were available to analyze. There was an overall statistically significant difference favoring probiotics compared with placebo in reducing the SCORAD index. Children with moderately severe disease were more likely to benefit. Duration of probiotic administration, age, and type of probiotic used did not affect outcome. Data from this meta-analysis suggest a modest role for probiotics in pediatric AD and the effect is seen in moderately severe rather than mild disease [94]. Lee et al meta-analyzed 10 double-blind randomized controlled clinical trials. And they found out that current evidence was more convincing for probiotics' efficacy in prevention than treatment of pediatric AD [95].

However, in a Cochrane Review by Boyle et al concluded that the evidence suggests that probiotics are not an effective treatment for eczema, and probiotic treatment carries a small risk of adverse events [96]. Another review of 13 studies of probiotics for treating established eczema by Williams at al did not show convincing evidence of a clinically worthwhile benefit [97].

Taken together, most of these metaanalytic studies show a mild-moderate benefit over placebo for the treatment and/or preventionof AD. However, several of the studies still show no benefit. Some probiotics appeared to be more effective than other probiotic preparations and in children with more severe disease. It seems that duration of probiotic administration, age, and type of probiotic used did not affect outcome. Although there was a reduction in clinical eczema score in infants, this effect was not consistent between studies and caution is advised in view of methodological concerns regarding included studies.
