A Role for Timp3 in Microbiota-Driven Hepatic Steatosis and Metabolic Dysfunction

• Loss of Timp3 combined with an HFD affects glucose tolerance and innate immunity
• Timp3−/− mice exhibit gut dysbiosis, liver steatosis, and systemic inflammation
• Defective BCAA metabolism in Timp3−/− mice contributes to the metabolic phenotype
• Gut microbiome modulation by antibiotics rescues inflammatory and metabolic status

SummaryThe effect of gut microbiota on obesity and insulin resistance is now recognized, but the underlying host-dependent mechanisms remain poorly undefined. We find that tissue inhibitor of metalloproteinase 3 knockout (Timp3−/−) mice fed a high-fat diet exhibit gut microbiota dysbiosis, an increase in branched chain and aromatic (BCAA) metabolites, liver steatosis, and an increase in circulating soluble IL-6 receptors (sIL6Rs). sIL6Rs can then activate inflammatory cells, such as CD11c+ cells, which drive metabolic inflammation. Depleting the microbiota through antibiotic treatment significantly improves glucose tolerance, hepatic steatosis, and systemic inflammation, and neutralizing sIL6R signaling reduces inflammation, but only mildly impacts glucose tolerance. Collectively, our results suggest that gut microbiota is the primary driver of the observed metabolic dysfunction, which is mediated, in part, through IL-6 signaling. Our findings also identify an important role for Timp3 in mediating the effect of the microbiota in metabolic diseases.

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