Jason Defuria - Academia.edu (original) (raw)

Papers by Jason Defuria

Proceedings of the National Academy of Sciences of the United States of America, 2013

Patients with type 2 diabetes (T2D) have disease-associated changes in B-cell function, but the r... more Patients with type 2 diabetes (T2D) have disease-associated changes in B-cell function, but the role these changes play in disease pathogenesis is not well established. Data herein show B cells from obese mice produce a proinflammatory cytokine profile compared with B cells from lean mice. Complementary in vivo studies show that obese B cell-null mice have decreased systemic inflammation, inflammatory B-and T-cell cytokines, adipose tissue inflammation, and insulin resistance (IR) compared with obese WT mice. Reduced inflammation in obese/insulin resistant B cell-null mice associates with an increased percentage of anti-inflammatory regulatory T cells (Tregs). This increase contrasts with the sharply decreased percentage of Tregs in obese compared with lean WT mice and suggests that B cells may be critical regulators of T-cell functions previously shown to play important roles in IR. We demonstrate that B cells from T2D (but not non-T2D) subjects support proinflammatory T-cell function in obesity/T2D through contact-dependent mechanisms. In contrast, human monocytes increase proinflammatory T-cell cytokines in both T2D and non-T2D analyses. These data support the conclusion that B cells are critical regulators of inflammation in T2D due to their direct ability to promote proinflammatory T-cell function and secrete a proinflammatory cytokine profile. Thus, B cells are potential therapeutic targets for T2D. immunometabolism | lymphocytes M ultiple studies support the concept that inflammation strongly associates with insulin resistance (IR), which, in addition to loss of islet function, defines type 2 diabetes (T2D) (1). Work implicating B cells in IR/T2D is limited. We showed B cells from T2D subjects secrete a proinflammatory cytokine profile, including an extraordinary inability to secrete the potent anti-inflammatory cytokine IL-10 and an elevated production of proinflammatory IL-8 compared with B cells from non-T2D subjects (2). Given the importance of B-cell IL-10 in preventing numerous inflammatory diseases (3, 4) and the links between IL-8 and T2D (5, 6), these data suggest that altered B-cell cytokine production plays an important role in initiating or promoting IR/T2D. Published analyses further support a role for B cells in IR and include studies of B cell-null New Zealand Obese (NZO) mice, which, in contrast to B cell-sufficient NZOs, fail to develop IR in response to obesity (7). These findings have been recently reproduced in studies showing obese B cell-null or B cell-depleted mice have less inflammation and IR than obese WT mice (8). Interestingly, T-cell cytokine production is decreased in obese B cell-null mouse adipose tissue (AT) (8), which raises the possibility that, in addition to production of a proinflammatory cytokine profile, B cells may function in IR by regulating the T cell-mediated inflammation known to drive disease pathogenesis (9, 10). We identified a proinflammatory T-cell ratio [defined by increased Th17 cells plus decreased regulatory T cells (Tregs)] in T2D patients that mirrors findings in obese mice (10-13). However, the likelihood that obesity-associated B-cell changes dictate T-cell function in human T2D is untested.

Brain Research, 2006

c-Jun N-terminal kinase (JNK), along with its upstream activator MEKK-1, is typically thought of ... more c-Jun N-terminal kinase (JNK), along with its upstream activator MEKK-1, is typically thought of as a stress-activated kinase that mediates apoptosis. However, additional studies indicate that the MEKK-1/JNK pathway mediates critical aspects of neuronal survival and differentiation. Herein, we demonstrate that transfection of differentiated NB2a/d1 cells with a construct expression constitutively activated (ca) MEKK-1 increases levels of phospho-dependent neurofilament (NF) immunoreactivity within perikarya, while expression of a dominant-negative (dn) form of MEKK-1 decreases it. Steady-state levels of perikaryal phospho-NF immunoreactivity are reduced and the increase resulting from expression of caMEKK-1 is prevented, by the JNK inhibitor SP600125, suggesting that JNK is a major downstream effector of MEKK-1 on NF phosphorylation. Unexpectedly, both caMEKK-1 and dnMEKK-1 inhibited neuritogenesis as well as translocation of NFs into newly elaborated neurites. The JNK inhibitor SP600125 also inhibited NF transport in a dosedependent manner. caMEKK-1 also prevented the increase in NF transport otherwise mediated by MAP kinase. Finally, both caMEKK-1 and dnMEKK-1 prevented initial neuritogenesis. These findings indicate that the MEKK-1/JNK pathway regulates critical aspects of initial outgrowth, and subsequent stabilization of axonal neurites.

Brain Research, 2007

The environmental neurotoxin arsenic has recently been associated with altered neurofilament (NF)... more The environmental neurotoxin arsenic has recently been associated with altered neurofilament (NF) content in sciatic nerve. We examined herein the impact of sodium arsenite (the inorganic form of arsenic) on NF dynamics. Treatment of differentiated NB2/d1 cells and cultured dorsal root ganglion neurons decreased NF transport into axonal neurites and increased perikaryal phospho-NF immunoreactivity. Both of these effects were prevented by a pharmacological inhibitor (SP600125) of c-jun terminal kinase and by expression of a dominant-negative form of this kinase. Arsenic-induced inhibition of NF transport was prevented by treatment with lithium, a selective inhibitor of glycogen synthase kinase-3beta. Pharmacological inhibitors of cyclin-dependent kinase 5 and p38 mitogen-activated protein kinase did not attenuate the effects of arsenic on NF dynamics. These latter findings suggest that this environmental neurotoxin could contribute to peripheral neuropathy by perturbing NF dynamics.

The Faseb Journal, Apr 1, 2009

The Journal of Immunology, 2014

ABSTRACT T cell inflammation plays critical roles in the development of obesity-associated type 2... more ABSTRACT T cell inflammation plays critical roles in the development of obesity-associated type 2 diabetes (T2D). B cells support T cell-mediated inflammation in T2D, but the mechanisms underlying lymphocyte cross-talk and the relative importance of T cell inflammation in human T2D remain untested. Using peripheral blood mononuclear cells (PBMC) and/or purified cells from T2D and non-diabetic (ND) subjects, we show that B cell contact upregulates a pro-inflammatory CD4+ Th17 T cell program in T2D. Neutralization of either B cell CD80/86 or the downstream production of T cell IL-17A/F significantly decreased production of classical diabetogenic cytokines (TNFα, IL-6) in samples from T2D subjects. Although monocytes, B cells and T cells produced TNFα in response to treatment of PBMCs with αCD3/CD28, monocyte TNFα production was independent of IL-17A/F, while IL-17F was critical for maximal TNFα production by both T and B cells. IL-17A/F neutralization also reduced IL-17A and IL-17F production by CD4+ T cells, indicating Th17 function is auto-regulated. We conclude that human B cell co-stimulation broadly supports Th17 cells, which in turn stimulate lymphocytes (but not monocytes) to produce the classical diabetogenic cytokine TNFα.

Obesity, 2015

T cell inflammation plays pivotal roles in obesity-associated type 2 diabetes (T2DM). The identif... more 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. 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. 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. 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.

Objective: Previous work suggested B cells play important roles in human periodontitis. Our new i... more Objective: Previous work suggested B cells play important roles in human periodontitis. Our new in vivo work definitely tested the hypothesis that B cells promote periodontitis-associated inflammation and bone loss. Method: Lean (6 wk-old) or obese (high fat diet for 10 weeks; n=8 each group), WT C57BL/6J and B-cell-null mice were orally infected with P. gingivalis strain A7436 or vehicle three times at two-day intervals. Body weight and glucose tolerance test assessed obesity and metabolic health at multiple time points. Six weeks after first infection (total time on diet for obese mice = 16 weeks), alveolar bone loss was determined by morphometric analysis. Gingival tissue gene expression was assessed by qRT-PCR. Serum cytokines and cytokine concentrations produced following in vitro stimulation of splenocytes were examined by multiplex assays. Result: Oral infection with P. gingivalis induced similar significant bone loss in lean WT and B-cell-null mice compared with vehicle-trea...

Lymphocytes play key roles in the chronic inflammation critical for T2D pathogenesis. T2D patient... more Lymphocytes play key roles in the chronic inflammation critical for T2D pathogenesis. T2D patients have an elevated ratio of pro- to anti-inflammatory T cells, and B cells that fail to produce anti-inflammatory IL-10. New data show that B cells from the diet-induced obesity (DIO) mouse model of T2D secrete a pro-inflammatory balance of cytokines, including relatively low IL-10 production, which mirrors our findings in T2D patients. DIO B cells do not secrete auto-antibodies, as evidenced by anti-nuclear antigen staining. Complementary metabolic studies show that B cell-null μMT mice resist the development of glucose intolerance (but not obesity) in response to DIO. Taken together, these data support the conclusion that a pro-inflammatory B cell cytokine balance, rather than antibodies, promotes T2D. To further define roles for B cells in T2D, we immunophenotyped DIO μMT splenocytes. Regulatory T cells (Tregs) expand in DIO μMT, while Tregs fail to expand in WT mice. These data are c...

T cell inflammation plays critical roles in the development of obesity-associated type 2 diabetes... more T cell inflammation plays critical roles in the development of obesity-associated type 2 diabetes (T2D). B cells support T cell-mediated inflammation in T2D, but the mechanisms underlying lymphocyte cross-talk and the relative importance of T cell inflammation in human T2D remain untested. Using peripheral blood mononuclear cells (PBMC) and/or purified cells from T2D and non-diabetic (ND) subjects, we show that B cell contact upregulates a pro-inflammatory CD4+ Th17 T cell program in T2D. Neutralization of either B cell CD80/86 or the downstream production of T cell IL-17A/F significantly decreased production of classical diabetogenic cytokines (TNFα, IL-6) in samples from T2D subjects. Although monocytes, B cells and T cells produced TNFα in response to treatment of PBMCs with αCD3/CD28, monocyte TNFα production was independent of IL-17A/F, while IL-17F was critical for maximal TNFα production by both T and B cells. IL-17A/F neutralization also reduced IL-17A and IL-17F production ...

Journal of Nutrition, 2009

Adipose tissue (AT) inflammation promotes insulin resistance (IR) and other obesity complications... more 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+

Proceedings of the National Academy of Sciences, 2014

The HLA-F adjacent transcript 10 (FAT10) is a member of the ubiquitinlike gene family that alters... more The HLA-F adjacent transcript 10 (FAT10) is a member of the ubiquitinlike gene family that alters protein function/stability through covalent ligation. Although FAT10 is induced by inflammatory mediators and implicated in immunity, the physiological functions of FAT10 are poorly defined. We report the discovery that FAT10 regulates lifespan through pleiotropic actions on metabolism and inflammation. Median and overall lifespan are increased 20% in FAT10ko mice, coincident with elevated metabolic rate, preferential use of fat as fuel, and dramatically reduced adiposity. This phenotype is associated with metabolic reprogramming of skeletal muscle (i.e., increased AMP kinase activity, β-oxidation and -uncoupling, and decreased triglyceride content). Moreover, knockout mice have reduced circulating glucose and insulin levels and enhanced insulin sensitivity in metabolic tissues, consistent with elevated IL-10 in skeletal muscle and serum. These observations suggest novel roles of FAT10 in immune metabolic regulation that impact aging and chronic disease. longevity | obesity | mammals

Proceedings of the National Academy of Sciences, 2013

Obesity, 2014

Objective: To investigate the role of TNF-like weak inducer of apoptosis (TWEAK) in pathological ... more Objective: To investigate the role of TNF-like weak inducer of apoptosis (TWEAK) in pathological adipose tissue (AT) remodeling and complications of obesity. Methods: Wild type (WT) and TWEAK knockout (KO) mice were fed normal diet (ND) or a high fat diet (HFD) for up to 17 weeks. Adipocyte death was induced using an established transgenic mouse model of inducible adipocyte apoptosis (FAT-ATTAC). Metabolic, biochemical, histologic, and flow cytometric analyses were performed. Results: TWEAK and its receptor, fibroblast growth factor-inducible molecule 14 (Fn14) were upregulated in gonadal (g)AT of WT mice after HFD week 4 and 24 h after induction of adipocyte apoptosis. Phenotypes of KO and WT mouse were indistinguishable through HFD week 8. However, at week 17 obese KO mice had 30% larger gAT adipocytes and gAT mass than WT mice, coincident with reduced adipocyte death, enhanced insulin signaling, Th2/M2 immune skewing, fewer thick collagen fibers, and altered expression of extracellular matrix constituents and modulators that is consistent with reduced fibrosis and larger adipocytes. KO mice were less steatotic and became more insulin sensitive and glucose tolerant than WT mice after HFD week 12. Conclusion: TWEAK constrains "healthy" gAT expansion and promotes metabolic complications in severe obesity.

Obesity, 2010

The role of adaptive immunity in obesity-associated adipose tissue (AT) inflammation and insulin ... more The role of adaptive immunity in obesity-associated adipose tissue (AT) inflammation and insulin resistance (IR) is controversial. We employed flow cytometry and quantitative PCR to assess T-cell recruitment and activation in epididymal AT (eAT) of C57BL/6 mice during 4-22 weeks of a high (60% energy) fat diet (HFD). By week 6, eAT mass and stromal vascular cell (SVC) number increased 3-fold in mice fed HFD, coincident with onset of IR. We observed no increase in the proportion of CD3+ SVCs or in gene expression of CD3, IFNγ, or regulated upon activation, normal T-cell expressed and secreted (RANTES) during the first 16 weeks of HFD. In contrast, CD11c+ macrophages (Mφ) were enriched 6-fold by week 8 (p < 0.01). SVC enrichment for T cells (predominantly CD4+ and CD8+) and elevated IFNγ and RANTES gene expression were detected by 20-22 weeks of HFD (p < 0.01), coincident with the resolution of eAT remodeling. HFD-induced T cell priming earlier in the obesity time course is suggested by (1) elevated (5-fold) IL-12p40 gene expression in eAT by week 12 (p ≤ 0.01) and (2) greater IFNγ secretion from PMA/ionophorestimulated eAT explants at week 6 (1 fold, p = 0.08) and week 12 (5 fold, p < 0.001). In summary, T cell enrichment and IFNγ gene induction occur subsequent to ATMφ recruitment, onset of IR and resolution of eAT remodeling. However, enhanced priming for IFNγ production suggests the contribution of CD4+ and/or CD8+ effectors to cell-mediated immune responses promoting HFDinduced AT inflammation and IR.

Journal of Leukocyte Biology, 2014

Individuals with T2D and PD suffer significantly from the ability of one disease to intensify the... more Individuals with T2D and PD suffer significantly from the ability of one disease to intensify the other. Disease-associated inflammation is one mechanism thought to fuel this pathogenic feed-forward loop. Several lines of evidence indicate that proinflammatory B cells promote T2D and PD; thus, B cells are top candidates for a cell type that predisposes PD in T2D. To test directly the role of B cells in T2D-associated PD, we compared outcomes from oral Porphyromonas gingivalis challenge of lean WT or B cell-null mice with outcomes from mice that were obese and insulin-resistant before challenge. Obese WT mice responded to oral P. gingivalis challenge with significant periodontal bone loss, whereas obese B cell-null mice were protected completely from PD. By contrast, lean WT and B cell-null mice suffer similar periodontal bone loss in response to oral pathogen. B cells from obese/insulin-resistant hosts also support oral osteoclastogenesis and both oral and systemic production of inflammatory cytokines, including pro-osteoclastogenic TNF-␣ and MIP-2, an ortholog of human IL-8. B cells furthermore impact AT inflammation in obese, P. gingivalis-infected hosts. Taken together, these data show that fundamentally different mechanisms regulate PD in lean and obese hosts, with B cells able to promote PD only if the hosts are "primed" by obesity. These results justify more intense analysis of obesity-associated changes in B cells that predispose PD in human T2D. J. Leukoc. Biol. 96: 000 -000; 2014.

Endocrinology, 2012

Menopause promotes central obesity, adipose tissue (AT) inflammation, and insulin resistance (IR)... more Menopause promotes central obesity, adipose tissue (AT) inflammation, and insulin resistance (IR). Both obesity and the loss of estrogen can activate innate and adaptive immune cells (macrophages, T cells). The respective impacts of weight gain and loss of ovarian hormones on AT inflammation and IR are poorly understood. Here we determined the temporal kinetics of fat accretion, AT inflammation, and IR over a 26-wk time course in ovariectomized (OVX) mice, a model of menopause. OVX and sham-operated (SHM) C57BL6 mice were fed a normal chow diet. Weight, body composition (magnetic resonance imaging), total and regional adiposity, activity, food intake, AT crown-like structures, biohumoral measures, and insulin sensitivity (insulin tolerance testing and homeostatic model assessment) were determined at wk 12, 20, and 26. Macrophages and T cells from perigonadal AT were immunophenotyped by fluorescence-associated cell sorting, and perigonadal adipose tissue (PGAT) gene expression was quantified by quantitative PCR. OVX mice (≈ 31 g) became fatter than SHM mice (≈ 26 g) by wk 12, but mice were equally insulin sensitive. PGAT of OVX mice contained more T cells but expressed higher levels of M2-MΦ (arginase-1) and T cell-regulatory (cytotoxic T-lymphocyte antigen 4) genes. At wk 20, both OVX and SHM mice weighed approximately 35 g and were equally insulin sensitive with comparable amounts of PGAT and total body fat. OVX mice became less insulin sensitive than SHM mice by wk 26, coincident with the down-regulation of PGAT arginase-1 (-20-fold) and cytotoxic T-lymphocyte antigen 4 (2-fold) and up-regulation of M1/Th1 genes CD11c (+2-fold), IL12p40 (+2-fold), and interferon-γ (+78-fold). Ovarian hormone loss in mice induces PGAT inflammation and IR by mechanisms that can be uncoupled from OVX-induced obesity.

Diabetes, 2007

We sought to determine the role of adipocyte death in obesity-induced adipose tissue (AT) inflamm... more We sought to determine the role of adipocyte death in obesity-induced adipose tissue (AT) inflammation and obesity complications. Male C57BL/6 mice were fed a high-fat diet for 20 weeks to induce obesity. Every 4 weeks, insulin resistance was assessed by intraperitoneal insulin tolerance tests, and epididymal (eAT) and inguinal subcutaneous AT (iAT) and livers were harvested for histological, immunohistochemical, and gene expression analyses. Frequency of adipocyte death in eAT increased from &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.1% at baseline to 16% at week 12, coincident with increases in 1) depot weight; 2) AT macrophages (ATM Phi s) expressing F4/80 and CD11c; 3) mRNA for tumor necrosis factor (TNF)-alpha, monocyte chemotactic protein (MCP)-1, and interleukin (IL)-10; and 4) insulin resistance. ATM Phi s in crown-like structures surrounding dead adipocytes expressed TNF-alpha and IL-6 proteins. Adipocyte number began to decline at week 12. At week 16, adipocyte death reached approximately 80%, coincident with maximal expression of CD11c and inflammatory genes, loss (40%) of eAT mass, widespread collagen deposition, and accelerated hepatic macrosteatosis. By week 20, adipocyte number was restored with small adipocytes, coincident with reduced adipocyte death (fourfold), CD11c and MCP-1 gene expression (twofold), and insulin resistance (35%). eAT weight did not increase at week 20 and was inversely correlated with liver weight after week 12 (r = -0. 85, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). In iAT, adipocyte death was first detected at week 12 and remained &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;or=3%. These results implicate depot-selective adipocyte death and M Phi-mediated AT remodeling in inflammatory and metabolic complications of murine obesity.

Endocrinology, 2009

The control of glucose metabolism is a complex process, and dysregulation at any level can cause ... more The control of glucose metabolism is a complex process, and dysregulation at any level can cause impaired glucose tolerance and insulin resistance. These two defects are well-known characteristics associated with obesity and onset of type 2 diabetes. Here we introduce the N-terminal dipeptidase, DPP2, as a novel regulator of the glucose metabolism. We generated mice with a neurogenin 3 (NGN3)-specific DPP2 knockdown (kd) to explore a possible role of DPP2 in maintaining metabolic homeostasis. These mice spontaneously developed hyperinsulinemia, glucose intolerance, and insulin resistance by 4 months of age. In addition, we observed an increase in food intake in DPP2 kd mice, which was associated with a significant increase in adipose tissue mass and enhanced liver steatosis but no difference in body weight. In accordance with these findings, the mutant mice had a higher rate of respiratory exchange than the control littermates. This phenotype was exacerbated with age and when challenged with a high-fat diet. We report, for the first time, that DPP2 enzyme activity is essential for preventing hyperinsulinemia and maintaining glucose homeostasis. Interestingly, the phenotype of NGN3-DPP2 kd mice is opposite that of DPP4 knockout mice with regard to glucose metabolism, namely the former have normal glucagon-like peptide 1 levels but present with glucose intolerance, whereas the latter have increased glucagon-like peptide 1, which is accompanied by augmented glucose tolerance.