Search

Objective: T cell inflammation plays pivotal roles in obesity-associated type 2 diabetes (T2DM). The identification of dominant sources of T cell inflammation in humans remains a significant gap in understanding disease pathogenesis. It was hypothesized that cytokine profiles from circulating T cells identify T cell subsets and T cell cytokines that define T2DM-associated inflammation. Methods: Multiplex analyses were used to quantify T cell-associated cytokines in αCD3/αCD28-stimulated PBMCs, or B cell-depleted PBMCs, from subjects with T2DM or BMI-matched controls. Cytokine measurements were subjected to multivariate (principal component and partial least squares) analyses. Flow cytometry detected intracellular TNFα in multiple immune cell subsets in the presence/absence of antibodies that neutralize T cell cytokines. Results: T cell cytokines were generally higher in T2DM samples, but Th17 cytokines are specifically important for classifying individuals correctly as T2DM. Multivariate analyses indicated that B cells support Th17 inflammation in T2DM but not control samples, while monocytes supported Th17 inflammation regardless of T2DM status. Partial least squares regression analysis indicated that both Th17 and Th1 cytokines impact %HbA1c. Conclusions: Among various T cell subsets, Th17 cells are major contributors to inflammation and hyperglycemia and are uniquely supported by B cells in obesity-associated T2DM., National Institutes of Health (U.S.) (Grants R21DK089270, 5R21DE021154, R56 DK096525, R24DK090963, and U01CA182898), Boston University. Genome Science Institute, Boston University. Hematology Training Program (Grant HL007501), National Institute of Diabetes and Digestive and Kidney Diseases (U.S.). Diabetic Complications Consortium, Boston University. Immunology Training Program (Grant AI007309), United States. Army Research Office (Institute for Collaborative Biotechnologies. Grant W911NF-09-0001)

Adipose tissue (AT) inflammation promotes insulin resistance (IR) and other obesity complications. AT inflammation and IR are associated with oxidative stress, adipocyte death, and the scavenging of dead adipocytes by proinflammatory CD11c+ AT macrophages (ATMPhi). We tested the hypothesis that supplementation of an obesitogenic (high-fat) diet with whole blueberry (BB) powder protects against AT inflammation and IR. Male C57Bl/6j mice were maintained for 8 wk on 1 of 3 diets: low-fat (10% of energy) diet (LFD), high-fat (60% of energy) diet (HFD) or the HFD containing 4% (wt:wt) whole BB powder (1:1 Vaccinium ashei and V. corymbosum) (HFD+B). BB supplementation (2.7% of total energy) did not affect HFD-associated alterations in energy intake, metabolic rate, body weight, or adiposity. We observed an emerging pattern of gene expression in AT of HFD mice indicating a shift toward global upregulation of inflammatory genes (tumor necrosis factor-alpha, interleukin-6, monocyte chemoattractant protein 1, inducible nitric oxide synthase), increased M1-polarized ATMPhi (CD11c+), and increased oxidative stress (reduced glutathione peroxidase 3). This shift was attenuated or nonexistent in HFD+B-fed mice. Furthermore, mice fed the HFD+B were protected from IR and hyperglycemia coincident with reductions in adipocyte death. Salutary effects of BB on adipocyte physiology and ATMPhi gene expression may reflect the ability of BB anthocyanins to alter mitogen-activated protein kinase and nuclear factor-kappaB stress signaling pathways, which regulate cell fate and inflammatory genes. These results suggest that cytoprotective and antiinflammatory actions of dietary BB can provide metabolic benefits to combat obesity-associated pathology.