707-P: Obesity-Associated Inflammatory Responses Are Significantly Modified by Insulin Sensitivity

by sugaradmin



Introduction and Objective: Systemic inflammation promotes insulin resistance (IR) and comorbidities like type 2 diabetes. Multiple CD4+ T cell subsets support inflammation in people with excess weight or obesity (herein, obesity). Autophagy is one key mechanism that regulates T cell-generated cytokines and thus inflammation. We tested the hypothesis that obesity-associated changes in T cell autophagy support inflammation and metabolic health declines by analyzing T cells from obese insulin-sensitive (IS) and IR subjects for cytokine production and for indicators of autophagy.Methods: Archived PBMCs from IS (HOMA-IR < 2.2; N=7) or IR (HOMA-IR > 2.5; N=7) subjects (BMI avg. 32.5, avg age 56.3 yrs) were recovered overnight with IL-2. CD4+ T cells were negatively isolated from PBMCs using magnetic beads, then stimulated with phorbol ester and ionomycin for 1.5 hours to induce (1) autophagy, analyzed by confocal microscopic quantification of lipidated LC3, p62, and LAMP1; and (2) inflammation, based on combinatorial cytokine profiles generated by partial least squares discriminant analysis of up to 25 cytokines produced by each cell in a single cell proteomics platform.Results: T cells from IR compared to IS subjects produced a cytokine profile dominated by IL-12 that was similar to a type 2 diabetes T-cell profile. T cells from men compared to women unexpectedly produced a more inflammatory profile. Confocal analysis showed defective autophagy in the IR group compared to IS, as indicated by reduced lipidated LC3B, increased P62 and decreased LC3B/LAMP1 colocalization.Conclusion: Obesity-associated IR is a more inflamed state than IS as expected, with CD4+ T cells from men specifically showing more production of cytokines typical of type 2 diabetes. IR also disrupted CD4+ T cell autophagy, with more severe effects in mens’ cells. These results indicate defective autophagy as a likely mechanistic underpinning of IR-associated T-cell inflammation in obesity.

Disclosure

A. Javidan: None. L.P. Bharath: None. E. Tevonian: None. B. Marrah: None. A. Konopka: Research Support; Dexcom, Inc. B.F. Miller: None. M.P. Bubak: None. D. Lauffenburger: None. B. Nikolajczyk: None.

Funding

National Institute on Aging (R01AG079525-03)



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