Gut microbiota-derived metabolites and their immunomodulatory roles
| Metabolite type | Immunomodulating property | Associated diseases | References |
|---|---|---|---|
| Metabolic end products | |||
| Short-chain fatty acids (SCFAs) | Support gut barrier integrity, reduce pro-inflammatory cytokines, promote Treg differentiation, neutrophil migration, and B cell class switching | Metabolic syndrome, cardiovascular disease, inflammatory bowel disease, colorectal cancer, and chronic kidney disease | [19–24] |
| Tryptophan and indole derivatives | Regulate gut barrier, motility, and hormone secretion; modulate immune responses via AhR receptor, promoting immune tolerance | Inflammatory bowel disease, irritable bowel syndrome, obesity, colorectal cancer | [18, 23, 25, 26] |
| De novo products | |||
| Branched-chain amino acids (BCAAs) | Crucial for protein synthesis, cell growth, and energy metabolism | Type 2 diabetes, obesity, cardiovascular disease, colorectal cancer | [17, 23, 27, 28] |
| Polyamines (PAs) | Maintain intestinal barrier, reduce oxidative stress, inhibit inflammatory cytokine production | Colorectal cancer, other tumors | [23, 29–31] |
| Bacterial-derived vitamins | Support metabolic processes, regulate DNA synthesis, energy metabolism, immune cell function | Cardiovascular disease | [18, 32, 33] |
| Modified host metabolites | |||
| Secondary bile acids (BAs) | Modulate activity of innate immune cells (macrophages, dendritic cells), regulate lipid and glucose metabolism | Metabolic dysfunction-associated steatotic liver disease, inflammatory bowel disease, colorectal cancer | [18, 34–36] |
AhR: aryl hydrocarbon receptor; Tregs: regulatory T cells