Elevated O-GlcNAcylation enhances pro-inflammatory Th17 function by altering the intracellular lipid microenvironment

Area of Science:

• Immunology
• Metabolic Disease
• Cellular Biology

Background:

• Chronic low-grade inflammation is linked to obesity, diabetes, atherosclerosis, cancer, and autoimmunity.
• CD4+ T helper 17 (Th17) cells secrete interleukin-17A (IL-17A) and are elevated in obesity, contributing to inflammation.
• The precise signaling pathways connecting nutrient excess to IL-17A-mediated inflammation remain unclear.

Purpose of the Study:

• To investigate the role of O-GlcNAcylation in linking nutrient excess to IL-17A production in CD4+ T cells.
• To elucidate the molecular mechanisms by which elevated O-GlcNAc levels influence Th17 cell activity and inflammation.

Main Methods:

• Utilized cytokine assays, quantitative real-time PCR, immunoprecipitation, and ChIP assays.
• Employed lipidomics and MS-based approaches to analyze cellular lipid environments.
• Studied naive CD4+ T cells from a diet-induced obesity murine model.

Main Results:

• Elevated O-GlcNAc levels were observed in CD4+ T cells from obese mice, correlating with increased IL-17A production.
• Increased binding of RORγt to the IL-17 gene promoter and enhancer was detected.
• Alterations in the intracellular lipid microenvironment and O-GlcNAcylation of ACC1 were found to enhance RORγt activity.

Conclusions:

• Increased O-GlcNAcylation of cellular proteins may serve as a critical link between excess nutrient intake and pathological inflammation.
• Targeting O-GlcNAcylation pathways could offer novel therapeutic strategies for inflammatory diseases associated with metabolic dysfunction.