Fig. 1
From: Endotoxin-induced alterations of adipose tissue function: a pathway to bovine metabolic stress
Endotoxin sources and transport in dairy cows. Dairy cows with conditions such as heat stress, subacute ruminal acidosis (SARA), lameness, mastitis, metritis, or consuming grain-rich diets are more likely to have circulating endotoxins in their bloodstream, a condition called endotoxemia. Elevated blood endotoxin levels correlate with alterations in microbiome composition, the proliferation of opportunistic bacteria, heightened intestinal permeability, and bacterial leakage. Endotoxins enter the circulation through (1) paracellular and (2) transcellular transport, facilitated by their interaction with high-density lipoproteins (HDL). HDL-endotoxin complexes enter blood circulation by scavenger receptor of the class B type I (SR-BI) or fatty acid translocase CD36. HDL-endotoxin complexes reach the adipose tissue, where endotoxins induce the polarization of macrophages towards the M1 phenotype while decreasing the abundance of M2, thus promoting inflammation. Created with BioRender.com