Figure 4

HIV infection results in metabolic alterations in the gut microbiota that differ from those induced by other diseases.

(A) The intestinal epithelium in patients with SLE and CDADt⁺. The gut microbiota has the capacity to metabolize Pro, Phe and Lys, amino acids that accumulate inside bacterial cells. These amino acids are excreted by the bacteria into the gastrointestinal tract environment and are transported through the mucosa. The metabolism of tryptophan by gut bacteria is not affected. (B) The intestinal epithelium in an HIV-infected individual. These individuals are characterized by a gut microbiota comprising a distinct set of bacterial species that has a reduced capacity to synthesize Pro, Phe and Lys. Therefore, their ability to transport these amino acids to the human cells is also impaired. In contrast, tryptophan and kynurenine produced in the dendritic cells and macrophages of the mucosa can be transported to the gut environment and can be metabolized by gut bacteria.