## 6 Therapies Targeting Gut Microbiota's Composition
#### Therapies Targeting Microbiota Composition in Atopic Dermatitis  
The factors that lead to the onset of allergic diseases during infancy are not completely comprehended at present. One well-accepted theory centers on the gut microbiota, wherein the mix and characteristics of beneficial bacteria interact with the evolving immune system. These interactions have the potential to impact immune development, potentially resulting \begin{table}
\begin{tabular}{c c c c} \hline \hline
**T**** therapy** & **Definition** & **Examples** & **Reference** \\ \hline \multirow{4}{*}{Probiotics} & Beneficial living microorganisms capable of & _Lactobacillus_ strains & \\  & establishing themselves in the human gut to & _L. reuteri_ (microencapsulated & [136; 137; 138] \\  & foster or reinstate a well-balanced gut & & (in yogurt) \\  & microbiota composition & _L. plantarum_ (capsules) & \\ \hline \multirow{4}{*}{Prebiotics} & Nutritional elements that nourish and encourage & Plant polyphenols & \\  & the development of a thriving gut & Fruits and vegetables (e.g., apples) & \\  & microbiota composition & Dietary fructans & [138; 139; 140; 141; 142; 143; 144] \\  & & microbiota composition & Foods high in inulin and/or & \\  & & oligofructose & \\ \hline \multirow{4}{*}{Diet intervention} & Ingestion of dietary components serving as & & \\  & sources of energy and nutrients for microbial & & \\  & growth, shaping the microbial & & \\  & community composition & & \\ \hline \multirow{4}{*}{Fecal microbiota transplantation} & Transference of fecal matter, containing a mixture & & \\  & of beneficial microorganisms, from a healthy & & \\  & donor to the gastrointestinal tract of a recipient & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Therapies targeting microbiota’s composition. Figure 3: AD pathogenesis regulation by the gut microbiota. in Th2 allergic responses. Consequently, there has been substantial scientific inquiry into preventative or therapeutic approaches targeting the gut microbiota [151; 152]. Intestinal permeability is increased in patients with AD. In recent years, additional data have emerged regarding the benefits of treatment with next-generation microbiome-based biotherapies in patients with AD [152]. Traditionally, treating _S. aureus_ infection in AD involved using broad-spectrum antibiotics to decolonize, but this approach carries the risk of promoting antibiotic resistance and disturbing the balance of beneficial microbes. Additionally, _S. aureus_ has developed mechanisms of antibiotic resistance. One potential method that was explored for managing _S. aureus_ abundance in AD involved dilute bleach baths; however, the results from various trials were inconclusive. Therefore, there is a need for more-targeted therapies that focus on restoring a healthy skin microbiome in AD patients, reducing the overgrowth of pathogenic triggers of AD, and promoting the recovery of beneficial commensal bacteria. These targeted therapies encompass various approaches, such as the use of probiotics, prebiotics, or synbiotics, reintroducing beneficial commensals to AD lesions, or even employing phage therapies. These options aim to provide more-effective and -sustainable solutions for managing AD while minimizing the risks associated with broad-spectrum antibiotics [129]. Probiotics and prebiotics complement each other when used to improve health. The combination of both concepts is called synbiotics, where prebiotics (or substrates) enhance the survival of probiotic strains and prolong the retention period of specific probiotics. Synbiotics can optimize, maintain, and restore the skin microbiota systemically (through ingestion) or through topical applications [153; 154; 155; 156]. Applying probiotic bacteria topically directly impacts the targeted skin area, reinforcing the body's natural defense mechanisms. Probiotics, similar to the body's native bacteria, can generate antimicrobial peptides that support skin immune responses and combat pathogens.