T cells dominate peripheral inflammation in obesity-associated diabetes

Abstract

Abstract Many studies have examined obese/insulin-resistant mice to conclude that macrophages dominate pathogenic inflammation in metabolic disease, but few studies have ranked chronic sources of peripheral inflammation in obese people across a natural spectrum of metabolic health. We compared the relative contributions of myeloid and T cells to peripheral inflammation in samples from metabolically healthy and unhealthy obese people to address disappointing outcomes from clinical trials of anti-inflammatories in obesity-associated type 2 diabetes (T2D). We stimulated PBMCs from obese subjects with euglycemia, prediabetes, or T2D with T cell-targeting CD3/CD28 or myeloid-targeting LPS, and measured supernatant cytokines over time. Cytokines increased with time following CD3/CD28, but LPS responses were time-independent. A series of surface marker and intracellular staining assays taking into account these temporal differences in cytokine production unexpectedly showed that T cells contribute more TNFα to peripheral inflammation than do myeloid cells from all subject groups. Bioinformatic modeling combining cytokine outcomes from all subjects, stimuli, and time points, indicated IFNγ generated by CD3/CD28 stimulation was most important for differentiating peripheral inflammation in T2D compared to non-T2D samples. This result was consistent with the previously identified Th1/Th17 profile in T2D. We conclude that human T cells dominate peripheral inflammation in obesity-associated T2D, and thus targeting T cells may be an effective approach for prevention/management of obesity-associated metabolic diseases. Supported by NIH Training Grants T32 DK007778 and TL1 UL1TR001998, R01DK108056, the Shared Resource Facility of the University of Kentucky Markey Cancer Center P30 CA177558, University of Kentucky College of Medicine, Barnstable Brown Diabetes and Obesity Center, The Center for Clinical and Translational Research (UL1TR000117), and NIH National Center for Advancing Translational Sciences UL1TR001998.