Effects in the gut include preventing pathogen invasion through bile salt modifications [26], mucus layer erosion when the host lacks dietary fiber [27], and accelerating DNA damage that promotes tumor formation [9, 10]. References for associations highlighted in the figure that are not mentioned in detail in the main text: autism [21, 33], Parkinson’s [64, 65], depression [29], multiple sclerosis [66], drug metabolism [54, 55], nonalcoholic fatty liver disease [67, 68], asthma [69], allergy [70, 71], heart disease [51], Celiac disease [72], IBD [27], and colorectal cancer [73–76]. dsDNA, double stranded DNA; GABA, gamma-aminobutyric acid; E. coli, Escherichia coli; IBD, inflammatory bowel disease (a collection of several intestinal disorders that includes Crohn’s disease and ulcerative colitis); PSA, capsular polysaccharide A from Bacteroides fragilis; TMA/TMAO, trimethylamine/ trimethylamine N-oxide. https://doi.org/10.1371/journal.ppat.1008370.g001 Although a variety of host pattern recognition receptors (PRRs) directly sense microbial “danger” signals, including those from microbiome symbionts, emerging evidence also supports the idea that we interact directly with microbes through additional cellular receptors. A recent study using a forward chemical genetics screen showed that MPPs fr...

In sickness and health: Effects of gut microbial metabolites on human physiology

10.1371/journal.ppat.1008370