Causes and consequences of low grade endotoxemia and inflammatory diseases

Increasing clinical observations reveal that persistent low-grade inflammation is associated with the pathogenesis of severe chronic diseases such as atherosclerosis, diabetes, and aging-related neurological diseases. Intriguingly, low levels of circulating Gram-negative bacterial endotoxin lipopolysaccharide (LPS) appear to be one of the key culprits in provoking a non-resolving low-grade inflammation. Adverse life styles, chronic infection, and aging can all contribute to the rise of circulating endotoxin levels and lead to low-grade endotoxemia. As a consequence, low-grade endotoxemia may skew host immune environment into a mild non-resolving pro-inflammatory state, which eventually leads to the pathogenesis and progression of inflammatory diseases. This review aims to highlight the recent progress in the causes and consequences of low-grade endotoxemia, as well as the emerging molecular mechanisms responsible.