*Therapeutic Properties of* Trichinella spiralis *(Nematoda) in Chronic Degenerative Diseases DOI: http://dx.doi.org/10.5772/intechopen.103055*


**Table 1.**

*Therapeutic effects of* T. spiralis *on cancer.*

#### *Therapeutic Properties of* Trichinella spiralis *(Nematoda) in Chronic Degenerative Diseases DOI: http://dx.doi.org/10.5772/intechopen.103055*

Among the existent animal models for autoimmune diseases, a model of type 1 diabetes in non-obese mice, when parasitized with ML, showed a decrease in the number of cytotoxic pancreatic cells, which in turn, delayed the disease progression up to 37 weeks [50]. Likewise, a suppressive effect on the disease was observed in parasitized animals with experimental autoimmune encephalomyelitis (EAE) in a study of new treatments for multiple sclerosis; here, there was an increase in the expression of the Th2 profile and a suppression of the disease signs and symptoms [51–53]. In the case of chronic intestinal disease, immunization with recombinant proteins derived from the TsP53, Cystatin-B and paramyosin proteins of *T. spiralis* (rTsP53, Tsp\_03420, and rTsPmy, respectively) led to a decrease in the expression of Th1-type cytokines and disease progression [54–56]; in addition, ML parasitosis and ESP immunization also showed anti-inflammatory effects [57–60]. Another animal model used to observe the therapeutic potential of *T. spiralis* is the collagen-induced rheumatoid arthritis model, where parasitosis with ML and immunizations with its extracts and the rTsPmy protein decreased disease progression, inflammation, and histopathological damage in the synovial tissue of the joint cavities [10, 61, 62].

In the case of allergic diseases, the use of ESPs from *T. spiralis* has also shown promising results in animal models of allergic asthma, a chronic inflammatory respiratory disorder triggered by an exacerbated Th2 response. In some cases, ML and its soluble extracts were used in mice with airway inflammation; as a result, improvements were observed in the disease progression, observed by the reduction of the levels of infiltrated eosinophils and ovalbumin-specific IgE, the decrease in IL-4, and the increase in IL-10 and TGF-β [49, 63]. This modulation was also observed in a mouse model of sepsis-induced acute lung injury where immunization with ESP from the parasite increased survival by 50% and reduced inflammation by a decreased production of pro-inflammatory cytokines [64]. These studies on autoimmune and allergic diseases are mentioned in **Table 2**.

### **4.3 Therapeutic potential of T. spiralis and other nematodes on experimental lupus mice models**

SLE is a chronic autoimmune disease that can affect all organs and tissues of the body due to a set of alterations in the innate and adaptive immune system, such as inefficient removal of apoptotic bodies, generation of autoantibodies that activate the complement cascade, and deposition of immune complexes in tissues that triggers an uncontrolled inflammatory process [65]. Renal, dermatological, and cardiovascular symptoms may occur as clinical features. It has an estimated worldwide prevalence between 6.5 and 178.0 per 100,000 people while its incidence varies from 0.3 to 23.7 cases per 100,000 people per year. The disease occurs in the young population, mainly females (9:1 ratio) [66]. SLE is a social and public health problem because 10–25% of patients who develop SLE die within 10 years of diagnosis. Currently, many of these patients die due to the uncontrolled inflammatory activity associated to the disease or because of the immunosuppressive treatment to which they are subjected [67]. Although the etiology of the disease is not completely known, its clinical heterogeneity suggests that different subsets of immune cells play a vital role in its pathogenesis, especially autoreactive B cells and autoantibodyproducing plasma cells. Likewise, T cells play a fundamental role in the progression of the disease due to the loss of the delicate balance between Th1 and Th2 responses [68]. Another pivotal part in this disease is the increased levels of a variety of proinflammatory cytokines, such as type I (IFN-α, IFN-β, IFN-κ), type II (IFN-γ) and


**Table 2.**

*Therapeutic effects of* T. spiralis *on autoimmune and allergic diseases.*

**12**

#### *Therapeutic Properties of* Trichinella spiralis *(Nematoda) in Chronic Degenerative Diseases DOI: http://dx.doi.org/10.5772/intechopen.103055*

type III (IFN-λ1, IFN -λ2, IFN -λ3 and IFN -λ4) interferons, tumor necrosis factor α (TNF-α), interleukins (IL)-1, IL-2, IL-6, IL-10, IL-12, IL-16, IL-17, IL-23, and others. Due to their correlation with the disease, they have been proposed as therapeutic candidates since there is a lack of effective treatments [69]. Thus, the study of new therapies based on immunomodulation that can ameliorate the symptoms and severity of the disease and improve the quality of life of patients has become highly relevant. To date, the few published reports focus on the therapeutic potential of the nematode *Acanthocheilonema viteae* in SLE, based on the use of a dominant ESP protein called ES-62, a widely tested glycoprotein with therapeutic effects in inflammatory diseases such as arthritis and asthma. This glycoprotein, administered in the MRL/Lpr lupus model, induced a decrease in the production of antinuclear autoantibodies, reduced aortic atherosclerotic lesions, and diminished fibrosis by up to 60%. These results have encouraged the use of drug-like small molecule analogs (SMAs) based on the active phosphorylcholine found on the N-glycans of ES-62, with similar outcomes to those obtained by the original protein, setting up a novel approach to control atherosclerosis in SLE [70, 71].

Phosphorylcholine effect on the intestinal microbiome was also studied in mice from the MRL/Lpr lupus model that received a synthetic conjugate called TPC (Tuftsin-Phosphorylcholine); this is made up of a tetrapeptide with immunostimulatory effects called Tuftsin, part of an IgG molecule, and phosphorylcholine. The mice treated with TPC had significant changes in the intestinal microbiome, such as the increase of the populations of beneficial bacteria of the genera *Turicibacter, Bifidobacterium, Mogibacteriaceae, Clostridiaceae, Adlercreutzia, Allobaculum* and *Anaeroplasma* and the reduction of pro-inflammatory bacteria, like the genus *Akkermansia*. Furthermore, TPC treatment was related to a significant decrease in proteinuria levels and an improvement in the disease progression [72].

Due to the immunomodulatory properties shown above, it is important that further studies be carried out, focused on other parasites or their derivatives with a potential therapeutic effect in lupus disease, like *T. spiralis*.

In 2004, Baeza et al*.* developed a murine model of experimental lupus that shares strikingly similar characteristics to the human disease, such as the presence of anti-histone, anti-nuclear and anti-coagulant antibodies, as well as anti-cardiolipin and anti non-bilayer phospholipid arrangements (NPA). NPA are three-dimensional structures in the cell membrane, different from the canonical bilayer, formed by the polar fractions of the phospholipids; this rearrangement causes the generation of auto antibodies. The lupus mice present glomerulonephritis, splenomegaly, arthritis-like joint lesions, alopecia and facial lesions resembling human malar erythema. IgG anti-NPA antibodies are found in lupus model mice and in some human patients with anti-phospholipid antibody syndrome [73–75].

The influence of *T. spiralis* infection have been studied in the experimental lupus murine model to find out whether the parasite had a therapeutic effect on the progression and outcome of this inflammatory disease. One of our experiments consisted in study mice were orally infected with 100 ML and at day 30 *post* infection induce lupus by intrasplenic administration of 100 μL of liposomes incubated with the promazine to trigger the formation of non bilayer phospholipid arrangement or NPA [76, 77]. The NPA administration was weekly by intraperitoneal until the end of the experiment. Blood samples were taken every 30 days for 6 months to determine the presence of pro- (IL-1α, IL-17a, IFN-γ and TNF-α) and anti-inflammatory cytokines (IL-4 and IL-10) by flow cytometry. In addition, body weight, clinical lesions and, antibodies to the ML were evaluated by ELISA [22].

The levels of IFN-γ and IL-1α did not show significant differences between experimental groups. **Figure 1** shows that first month *post-infection*, low levels of IL-4 and IL-10 were observed in mice with lupus and lupus infected mice respect to infected. However, unexpected at fifth moth *post-infection*, the lupus infected mice group increased the IL-4 levels (**Figure 1a**); in accordance with data published in different experimental models of inflammatory diseases for arthritis, colitis and airway inflammations [2], is possible that a modulation towards an anti-inflammatory-type response by IL-4 along with the induction of Tregs initiated by IL-10 (**Figure 1b**) were observed. In our observations, levels of IL-17a were higher in the lupus infected mice respected to lupus mice (**Figure 1c**), which contrasts with data shown by Cheng and collaborators, who found that the decrease in this cytokine did not produce any effect in an arthritis model [10]. IL-17a is commonly related to an inflammatory response, but also participate in tissue regeneration [78]. The overexpression of TNF-α in the infected mice and lupus infected mice (**Figure 1d**) is in accordance with results reported by Kim and Moudgil in 2008, using an arthritis model developed by the administration of heat-killed *M. tuberculosis* in rats and subsequently administered with TNF-α and IFN-γ. Authors observed that high levels of TNF-α had a protective effect against arthritis progression [79]. Our data shows absence of arthritis-like lesions in lupus infected mice in concordance with data reported by Cheng and collaborators in 2018, where a therapeutic effect of *T. spiralis*

#### **Figure 1.**

*FMI levels of intracellular cytokines in peripheral blood of the experimental mice. Bar graphs show the levels of cytokines IL-4, IL-10, IL-17a, and TNF-α. Untreated (NC, negative control), infected (I), lupus (L), and lupus infected (L + I) mice. Circles indicate significant differences, asterisks trends between study groups, and square brackets the time during which the statistical difference is valid. Orange color stands for 5 months and blue color for 6 months of study. To determine the differences (p < 0.05), a two-way ANOVA for independent samples was performed. FMI stands for fluorescence mean intensity.*

*Therapeutic Properties of* Trichinella spiralis *(Nematoda) in Chronic Degenerative Diseases DOI: http://dx.doi.org/10.5772/intechopen.103055*

#### **Figure 2.**

*Physical and clinical characteristics of the mice studied. (a) Bar graphs show serum levels of antibodies specific for T. spiralis. Untreated (NC, negative control), infected (I), lupus (L) and lupus infected (L+I) mice. Circles indicate significant differences between groups. To determine differences (p < 0.05), a two-way ANOVA for independent samples was performed. (b) Trichinoscopies of mouse diaphragms from the P (b1) and P+L (b2) groups analyzed by optic microscopy. (c) Photos show some of the lesions presented by mice at the end of the study, indicated by colored arrows; black arrows show joint lesions, yellow arrows facial lesions, orange arrows alopecia spots, and blue arrows piloerection. (c1) infected (I), (c2) lupus (L), and (c3) lupus infected (L+I) mice.*

in a collagen-induced arthritis mouse model was observed by promoting tolerance, suppressing inflammatory T-cell activity and reducing tissue damage [10]. IgG serum antibodies to *T. spiralis* was similar between infected and lupus infected mice (**Figure 2a**). Trichinoscopy of all infected mice showed similar parasite loads in diaphragms (**Figure 2b**). Clinical lesions were only observed in lupus mice (**Figure 2c**). At the beginning of the third month, half of the L group had developed alopecia and facial lesions, and more than half of these mice showed arthritis-like articular lesions.

In conclusion, data suggest a *T. spiralis* a protective effect during 5 months through the production of anti-inflammatory cytokines; this effect can delay or reduce the appearance of some of the lupus-related signs. It is imperative to continue the research to gather more data on the mechanisms of immunomodulation triggered by *T. spiralis* to look out for future lupus therapies.

### **5. Risks of treatment with helminths or helminth products**

Nowadays, there are number for alternative therapies to autoimmune disorders, including the use helminth infection; however, these "treatment" is neither attractive nor etic because the use of live worms. Indeed, in the experimental approach, there are many unanswered questions such as appropriate dosing regimens and optimal timing of treatment, in addition to how host genetics, diet, and environment influence disease progression [80, 81]. Because helminthenabled immunomodulation can extend to other unknown effects on the immune response to other pathogens or vaccines, these interactions can induce immune downregulation and may lead to predispositions to other types of infections, such as those caused by *Mycobacterium tuberculosis* or malaria [1]. Even though some helminths reduce the risk of developing adenocarcinoma associated with *Helicobacter pylori*, others increase the development of several types of cancer, such as trematodes of genus *Opisthorchis*. In this case, it is important to consider that although all vermiform organisms are considered helminths, there are notable metabolic differences between them; in flatworms (e.g., *Opisthorchis*), the parasite–host contact is carried out through their tegument and involves a whole range of surface proteins. On the other hand, nemathelminths (e.g., *Trichinella*) contact its host through the cuticle that surrounds the parasite, mainly made up of chitin, and turning the ESP into the main antigens recognized by the immune response [1].

In the case of *T. spiralis*, there are some concerns about its use as a therapeutic reagent, the most important being the possible induction of an antibody response, which may reduce the efficacy of its ESP. Even though many of the reports do not use adjuvants or the administrations are intraperitoneally given for short time periods, limiting the response against the parasite proteins, the efficacy could be negatively affected if they are used repeatedly or for prolonged time periods due to the probable production of neutralizing antibodies. Another problem that has arisen from this kind of treatment is the complex composition of the ESP itself, which may lead to the occurrence of side effects or immunological interference, if ESP are used in their entirety. This complexity in composition also represents a problem for scaling their production, limiting ESP clinical use; thus, the characterization of each component that has immunoregulatory properties is of upmost importance [64].

### **6. Conclusion**

Although helminths are different, both biologically and morphologically, most have developed similar strategies to evade innate and adaptive host immune responses, allowing them to establish prolonged parasitism. Among these strategies, the capacity of immunosuppression or immunomodulation stands out, turning helminths into a focus of attention for the study of new therapeutic strategies that allow improving the quality of life during chronic degenerative diseases. The study of *Trichinella spiralis* has shown to have immunomodulatory potential in experimental models of cancer, allergy and autoimmune diseases. In the case of experimental murine lupus, infection with *Trichinella* delayed the presence of signs of disease for 5 months and increased the levels of the cytokines IL-10 and IL-4. To our knowledge, this is the only work reporting the therapeutic effects of *T. spiralis* in an experimental mouse model of lupus.

### **Acknowledgements**

The authors thank Carla Landa-Saldivar and Sandra Sánchez-Barbosa for their technical assistance and Institute for Diagnostic and Epidemiological Reference animal house veterinary technicians for the excellent animal care. This study was grant supported by National Polytechnic Institute (Instituto Politécnico Nacional), Mexico *Therapeutic Properties of* Trichinella spiralis *(Nematoda) in Chronic Degenerative Diseases DOI: http://dx.doi.org/10.5772/intechopen.103055*

(SIP20210418 to IB and SIP 20210382 to CWB) and National Council for Science and Technology (CONACYT), Mexico (Internal number 818877). Authors are National System of Researchers fellows (CONACYT). The native speaker Sandra Sánchez-Barbosa conducted the critical review of the English language.
