Association between circulating lipopolysaccharide (LPS) and metabolic diseases (such as Type 2 Diabetes and atherosclerosis) has shifted the focus from high-fat high-cholesterol containing western type diet (WD)-induced changes in gut microbiota per se to release of gut bacteria-derived products (e.g., LPS) into circulation due to intestinal barrier dysfunction as the possible mechanism for the chronic inflammatory state underlying the development of these diseases. We demonstrated earlier that oral supplementation with curcumin attenuates WD-induced development of Type-2 diabetes and atherosclerosis. Poor bioavailability of curcumin has precluded the establishment of a causal relationship between oral supplementation and it's in vivo effects. We hypothesized that curcumin attenuates WD-induced chronic inflammation and associated metabolic diseases by modulating the function of intestinal epithelial cells (IECs) and the intestinal barrier function. The objective of the present study was to delineate the underlying mechanisms. Human IEC lines, Caco-2 and HT-29 were used for these studies and modulation of direct as well as indirect effects of LPS on intracellular signaling as well as tight junctions were examined. Pre-treatment with Curcumin significantly attenuated LPS-induced secretion of master cytokine IL-1 from IECs and macrophages. Furthermore, curcumin also reduced IL1-induced activation of p-38 MAPK in IECs and subsequent increase in expression of Myosin Light Chain Kinase involved in the phosphorylation of tight junction proteins and ensuing disruption of their normal arrangement. The major site of action of curcumin is, therefore, likely the IECs and the intestinal barrier and by reducing intestinal barrier dysfunction, curcumin modulates chronic inflammatory diseases despite poor bioavailability.
- Chronic Inflammatory Metabolic diseases
- Intestinal epithelial cell inflammation
- Tight Junction proteins
- Copyright © 2017, American Journal of Physiology-Cell Physiology