**3. Current possibilities of the gut microbiota modulation in chronic diseases and future development**

Current knowledge suggests that gut microbiota and gut dysbiosis could play an important role in the etiology and pathogenesis of chronic diseases and gut microbiota modulation could be an effective tool for their supportive treatment.

Nutrition significantly affects the diversity, composition, and function of the gut microbiota and human health at an early age, in adulthood, and also in old age. Diet high in fiber, fermented foods, and a diet containing omega- 3 fatty acids have a very positive effect on the composition and metabolic activity of beneficial microorganisms of the gastrointestinal tract. Diet represents a safe, readily modifiable, and cheap method of early intervention in chronic diseases, which may have significant health benefits by regulating the gut microbiota and mucous barrier [21].

New knowledge about the mutual communication between gut microorganisms and the whole organism makes it possible to develop new and effective methods of modulating the gut microbiota using beneficial microorganisms or their metabolites [22].

Probiotics are proposed as alternatives to antimicrobial drugs, and they can be an adjuvant therapy in the treatment of diseases associated with gut dysbiosis. Prebiotics modulate gut microbiota by stimulating the growth and metabolic activity of gutbeneficial microorganisms [23]. It has been shown that the positive effect of probiotic bacteria, prebiotics, or natural bioactive substances in functional foods can effectively reduce the incidence of chronic diseases [24]. The beneficial effects of probiotics on the host can be significantly improved by potentiated probiotics [25], which contain a suitable combination of probiotic bacteria with natural bioactive substances such as oligosaccharides, polyunsaturated fatty acids, and plant extracts [26–29]. Experiments in gnotobiotic piglets have shown that polyunsaturated fatty acids increased the adherence ability of lactobacilli and their inhibitory effect on the adhesion of *Escherichia coli* O8: K88ab: H9 in the gut [26, 27]. Effects of probiotic (PRO) *Lactobacillus plantarum* and combination of PRO and prebiotic (PRE) inulin enriched with oligofructose (2%) and PRO with Linioleum virginale (O) on gut bacteria in 1,2-dimethylhydrazine exposed rats were studied. It was shown that combinations of PRO-O and PRO-PRE had a synergistic effect which was higher than the effect of administering only PRO [28]. Preventive application of *L. plantarum* LS/07 alone or in combination with inulin to rats with chronic inflammation reduced the inflammatory process in the gut mucosa by down-regulating of pro-inflammatory cytokine synthesis and suppression of NF-κB activity in mucosal cells [29].

The next-generation probiotics hold promise to treat diverse medical conditions, and they can be more effective than single or multi-strains commercial probiotics. Moreover, several different strains with proven health benefits such as *Akkermansia muciniphila*, *Faecalibacterium prausnitzii*, *Bacteroides fragilis, Bacteroides uniformis*, *Eubacterium hallii,* and members of the Clostridia clusters IV, XIVa, and XVIII. can be considered candidates for the next generation of probiotics and other microbiotabased drugs. The development of the next generation probiotics holds promise for innovation in both the food/feed sector and the pharmaceutical industry [30].

New knowledge of the role of microbiota in health and diseases allows to expand the possibilities of administration of probiotics, in relation to their application form, depending on the intended use. Increasing interest in the application of probiotics in clinical practice will likely require specific regulatory approaches, if they are administered in a diseased population. More recently, the European Food Safety Authority has defined a new "live biotherapeutic products" (LBP) category, clarifying pharmaceutical expectations. Similar to all products intended to prevent or treat diseases, LBPs will have to be registered as medicinal products to reach the market in the USA and Europe [31].

Fecal microbiota transplantation (FMT) is the administration of fecal microbiota from a healthy person (donor) to a patient with a disease associated with dysbiosis. FMT is an effective therapeutic alternative for *Clostridium difficile* infection (CDI)

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

but could be a promising therapeutic approach in patients with other diseases such as inflammatory bowel diseases (IBD), irritable bowel syndrome, metabolic syndrome, and obesity [32, 33]. It is hypothesized that FMT improves colonization resistance of recipient gut microbiota, but the mechanisms are not well understood. Fecal microbiota can be transplanted also in lyophilized encapsulated form. Another possibility of FMT is to use human gut microbiota cultured anaerobically in vitro. In choosing the route of FMT administration, the indication should be taken into account [12, 34–36].

Next-generation-based therapies, including synthetic stool products or bacterial consortia, currently have been coming to the fore, as an alternative to FMT, as they have much fewer side effects. It was shown that gut microbiota could be effectively modulated by the administration of defined microbiota. Application of 33 bacterial strains, isolated from human stool or a stool substitute mixture comprising a multi-species community of bacteria, may be protective against *C. difficile* or S. *typhimurium* enteral infection. The defined consortium of 8 bacterial strains (altered Schaedler flora) could be effective to diminish fecal urease activity and ammonia production [12, 37, 38].

Autoprobiotic technology can be applied to modulate gut microbiota using selected indigenous probiotic bacteria isolated from a healthy donor. The isolated bacteria are stored in cryobanks and returned to the host if dysbiotic conditions occur [39].

One of the new therapeutic approaches targeting the gut microbiota is based on metabolites of microorganisms—"postbiotics". They are produced, modulated, or degraded by the microbiota and act directly on the host with their metabolic and signaling function. These metabolites, such as short-chain fatty acids, flavonoids, or organic acid taurine, serve as a means of communication in interactions between hosts and microorganisms. Postbiotics target microbial signaling pathways by mitigating the negative effects of deficiency or excess of metabolites involved in signaling pathways. Postbiotics do not affect the gut dysbiosis, but have the potential to correct its negative effects. In contrast to the application of living microorganisms, their dosage and methods of application follow the principles of pharmacokinetics [40]. The term "pharmabiotics" refers not only to living microorganisms but also to dead or altered microorganisms, such as bacteria, but also their metabolites [41].
