**4. Personalized and targeted microbiota modulation and its potential for more efficient prevention and treatment of chronic diseases**

Current knowledge suggests that the gut microbiome plays an extraordinary role in the development of chronic diseases. A better understanding of the mechanisms of its involvement in the pathogenesis of diseases is crucial for successful and effective microbiota modulation. The composition and functional characteristics of a healthy microbiome remain to be defined. Certain parameters such as the diversity of the microbiota, an abundance of certain genera (i.e., *Bifidobacteria*, *Lactobacillus*, etc.), or specific ratios between main bacterial phyla are considered markers of a healthy microbiota. The characterization of a healthy microbiota would make it possible to optimize nutrition and modify the microbiota to prevent diseases and to improve the effectiveness of therapy in people with gut dysbiosis and associated diseases [42].

Although some diseases have been correlated with dysbiosis, it is not clear if dysbiosis is a cause or consequence. Several trials have shown that therapies correcting dysbiosis, including fecal microbiota transplantation and probiotics, are promising in inflammatory bowel disease [10]. However, current knowledge shows that fecal microbiota transplantation does not have the same high effectiveness in inflammatory bowel disease as it does in *Clostridium difficile* infection. Dysbiosis occurs in both diseases, but the etiology and pathogenesis of inflammatory bowel disease are more complex in comparison with *Clostridium difficile* infection [43] and the same problem of complexity applies to many other diseases. Various strategies have emerged in the modulation of the gut microbiota in the prevention or treatment of diseases. Progress in this area is hampered due to ambiguities in the exact role of the microbiota in a given disorder, variations in the phenotype of the human disease, and variability in the formulation and delivery of the intended therapies. The use of gut microbiota modulation in medical practice requires a significant shift on all these fronts [41]. It is known that pathogenic microorganisms can cause various diseases, including cancer, and gut dysbiosis plays a very negative role in the pathogenesis of diseases. It is, therefore, reasonable to assume that modulation of gut microbiota may be a very effective means of prevention, but also supportive therapy for many chronic diseases shortly.

We have effective means to fight against chronic diseases through gut microbiota modulation. The suitable diet, probiotics, prebiotics, postbiotics, and gut microbiota transplantation represent them. However, what we need the most is a strategy for their effective use to the patient in individual's illness. Personalized and targeted modulation of gut microbiota has all the prerequisites to become a key strategy for the prevention and supportive therapy of chronic diseases [44, 45]. Personalized and precision medicine creates prerequisites for the application of new methods of treatment for many chronic diseases aimed at modifying the gut microbiome, including cancer therapy. Taking into account the role of gut microorganisms in disease pathogenesis could significantly contribute to increasing the effectiveness of their treatment [46].

Patient-tailored manipulation of the human microbiome may enable the development of precision microbiome-targeting treatment for a variety of multi-factorial disorders. More effective methods of adjusting the gut microbiome can be personalized probiotics and prebiotics, personalized nutrition taking into account the composition and functionality of the gut microbiota, postbiotics containing metabolites of microorganisms affecting the communication of microorganisms with the host, and phage therapy. However, their use in clinical practice requires the establishment of standard sampling procedures, their analysis, and interpretation of the obtained results. The use of personalized and precision medicine procedures will thus make it possible to streamline the diagnosis and therapy of diseases in which the gut microbiome plays an important role [47].

The development of precision probiotics, next-generation prebiotics resulting from a better understanding of metabolic interactions among members of the microbial ecosystem, and personalized dietary therapies tailored to an individual's microbiota will form the new frontier in the field of personalized medicine [48].

It can be assumed that new knowledge will make it possible to increasingly use the modulation of the gut microbiota to improve the effectiveness of disease prevention and their supportive therapy. It is highly likely that a suitable solution will be the application of a personalized approach using various possibilities of gut microbiota modulation through beneficial microorganisms or diet. However, it will be necessary to gain new knowledge about the composition and functionality of the optimal gut microbiota and the role of gut dysbiosis in the pathogenesis of diseases [49].

Effective modulation of the gut microbiome will require research and development of more effective methods and products for personalized and targeted

### *Personalized and Targeted Gut Microbiome Modulation in the Prevention and Treatment… DOI: http://dx.doi.org/10.5772/intechopen.110046*

modulation of the gut microbiome [24, 45]. Personalized medicine uses and combines genomic and clinical data to more accurately predict an individual's susceptibility towards development of the disease and his response to treatment. Personalized approach thus allows optimization of patient care. Personalized medicine approach and targeted approach in gut microbiota modulation should be based on analyses of the patient's clinical data and an analysis of the patient's gut microbiome and metabolome that reveals the specific changes in his gut microbiota diversity, composition, and function. These analyses allow using personalized and targeted gut microbiota modulation, by the application of beneficial microorganisms, their consortia, and their metabolites. It can be assumed that this method of modulation will in many cases require a combination of personalized probiotics, probiotic strains with specific effects, and metabolites of microorganisms—postbiotics.

The study of the application of personalized probiotics was conducted on 48 patients. The aim of this study was to determine changes in selected markers within the microbiota after 3 months of treatment by the personalized probiotic supplement. The probiotic composition (species, number of species, and number of CFU) of the probiotic mixture was designed based on gut microbiome analysis and prepared for each patient separately. After 3 months of probiotic supplementation, control samples were analyzed. Data confirmed a statistically significant increase of specific beneficial bacterial groups (lactobacilli, bifidobacteria, and actinobacteria) as well as the total number of species, thus increasing the overall diversity of the microbiota, which is considered a marker of a healthy gut microbiome. Results showed that the probiotic supplementation improved stool frequency in both cases—constipation and also diarrhea. The study confirmed the significance of a personalized approach in probiotic supplementation [50]. Of course, further data and studies are needed to demonstrate the effectiveness of a personalized approach in the clinical field.

It can be expected that also a new method of personalized and targeted modulation of gut microbiome combined with the auto-transplantation of *ex vivo* modulated patient's gut microbiota will be developed in near future for clinical practice [45, 51]. Innovative animal experimental models and clinical studies will greatly aid the shift in gut microbiome research and modulation that will enable the production of highquality products for the patients [52].
