Diet and microbiome in the beginning of the sequence of gut inflammation

Figure 2 Metabolic epithelial changes in dysbiosis due to loss of obligate anaerobes. A: The eubiosis microbiome contains a significant number of obligate anaerobes that convert dietary fiber into short chain fatty acids (SCFAs), contributing to a C2-type epithelial trophism with high oxygen consumption (O₂), which limits its diffusion to the intestinal lumen and maintains the epithelium in relative hypoxia; B: The deterioration of the microbiome with loss of obligate anaerobes and SCFAs orients the metabolism of the epithelium to a C1-type, with greater glucose fermentation, low O₂ consumption, and generation of lactic acid and nitric oxide (NO). The higher partial pressure of the O₂ not consumed by the C1 colonocytes and the conversion of NO to nitrate (NO₃^-) causes an overgrowth of facultative anaerobes; C: The persistence of the loss of strict anaerobes and their fermentation products ends up causing epithelial damage (via polymorphonuclear neutrophils R-spondin 2), the response of which is crypt hyperplasia and the multiplication of stem cells (SCs). The sustained increase in NO₃^- and O₂ contributes to the persistence of facultative anaerobes and dysbiosis. This figure is based upon data published in reference 39.