Fortunately, the immune system also has evolved to not only contain the microbiota, but preserve the symbiotic relationship between host and microbiota. The homeostasis in mucus layer in the gut is maintained by a system of checks and balances between potentially pro-inflammatory cells, such as Th1 cells that produce interferon-γ, lymphoid cells with cytokine effector features resembling Th2 and Th17 cells, and anti-inflammatory regulatory T cells (Hooper et al 2012). There are different regions of the gastrointestinal tract that differ in function and microbiota (Walter et al 2011 and Nicholson et al 2012). The divided sections allow for distinction between nutrient absorption and digestion to be separated distally from the microbiota in order to reduce conflicts (Walter et al 2011). The chemical communication between the host and microbiota varies based on location and can influence factors by signaling through low molecular weight metabolites, peptides, and proteins (Nicholson et all 2012). PH levels in the stomach, secretion of bile salts, proteins such as immunoglobulin A (igA) all mediate microbial levels in the stomach as well (Walter et al 2011). Chemical methods also combat microbial dangers, for example, the low pH of stomach acid prevents microbial growth. Bile salts are bacteriocidal, and igA also targets bacteria although mechanisms are still not well
Fortunately, the immune system also has evolved to not only contain the microbiota, but preserve the symbiotic relationship between host and microbiota. The homeostasis in mucus layer in the gut is maintained by a system of checks and balances between potentially pro-inflammatory cells, such as Th1 cells that produce interferon-γ, lymphoid cells with cytokine effector features resembling Th2 and Th17 cells, and anti-inflammatory regulatory T cells (Hooper et al 2012). There are different regions of the gastrointestinal tract that differ in function and microbiota (Walter et al 2011 and Nicholson et al 2012). The divided sections allow for distinction between nutrient absorption and digestion to be separated distally from the microbiota in order to reduce conflicts (Walter et al 2011). The chemical communication between the host and microbiota varies based on location and can influence factors by signaling through low molecular weight metabolites, peptides, and proteins (Nicholson et all 2012). PH levels in the stomach, secretion of bile salts, proteins such as immunoglobulin A (igA) all mediate microbial levels in the stomach as well (Walter et al 2011). Chemical methods also combat microbial dangers, for example, the low pH of stomach acid prevents microbial growth. Bile salts are bacteriocidal, and igA also targets bacteria although mechanisms are still not well