Total lipopolysaccharide from the human gut microbiome silences toll-like receptor signaling

We performed computational and experimental analysis of healthy human fecal samples to examine the TLR4 signaling capacity of the gut microbiota. This analysis revealed that an immuno-inhibitory activity of LPS, conserved across the Bacteroidales and derived from an under-acylated structural feature, silences TLR4 signaling for the entire consortium of organisms inhabiting the human gut. Comparative analysis of metagenomic data from the Human Microbiome Project and healthy donor samples indicates that immune silencing via LPS is a microbe intrinsic feature in all healthy adults.