Raghu Adya

Identification of chemerin receptor (ChemR23) in human endothelial cells: chemerin-induced endothelial angiogenesis

Chemerin acting via its distinct G protein-coupled receptor CMKLR1 (ChemR23), is a novel adipokine, circulating levels of which are raised in inflammatory states. Chemerin shows strong correlation with various facets of the metabolic syndrome; these states are associated with an increased incidence of cardiovascular disease (CVD) and dysregulated angiogenesis. We therefore, investigated the regulation of ChemR23 by pro-inflammatory cytokines and assessed the angiogenic potential of chemerin in human endothelial cells (EC). We have demonstrated the novel presence of ChemR23 in human ECs and its significant up-regulation (P<0.001) by pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6. More importantly, chemerin was potently angiogenic, as assessed by conducting functional in-vitro angiogenic assays; chemerin also dose-dependently induced gelatinolytic (MMP-2 & MMP-9) activity of ECs (P<0.001). Furthermore, chemerin dose-dependently activated PI3K/Akt and MAPKs pathways (P<0.01), key angiogenic and cell survival cascades. Our data provide the first evidence of chemerin-induced endothelial angiogenesis and MMP production and activity.

Omentin-1, a Novel Adipokine, Is Decreased in Overweight Insulin-Resistant Women With Polycystic Ovary Syndrome: Ex Vivo and In Vivo Regulation of Omentin-1 by Insulin and Glucose

OBJECTIVE—Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Recent studies have shown that plasma omentin-1 levels decrease with obesity. Currently, no data exist on the relative expression and regulation of omentin-1 in adipose tissue of women with PCOS. The objective of this study was to assess mRNA and protein levels of omentin-1, including circulating omentin-1, in omental adipose tissue of women with PCOS and matched control subjects. Ex vivo and in vivo regulation of adipose tissue omentin-1 was also studied. RESEARCH DESIGN AND METHODS—Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of omentin-1. Plasma omentin-1 was measured by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue omentin-1 were analyzed ex vivo. The in vivo effects of insulin (hyperinsulinemia) on omentin-1 levels were also assessed by a prolonged insulin-glucose infusion. RESULTS—In addition to decreased plasma omentin-1 levels in women with PCOS (P < 0.05), compared with control subjects, there was significantly lower levels of omentin-1 mRNA (P < 0.01) and protein (P < 0.05) in omental adipose tissue of women with PCOS (P < 0.01). Furthermore, in omental adipose tissue explants, insulin and glucose significantly dose-dependently decreased omentin-1 mRNA expression, protein levels, and secretion into conditioned media (P < 0.05, P < 0.01). Also, hyperinsulinemic induction in healthy subjects significantly reduced plasma omentin-1 levels (P < 0.01). CONCLUSIONS—Our novel findings reveal that omentin-1 is downregulated by insulin and glucose. These may, in part, explain the decreased omentin-1 levels observed in our overweight women with PCOS.

Omentin : a novel link between inflammation, diabesity, and cardiovascular disease

Obesity has reached pandemic proportions and is associated with serious cardiometabolic sequelae including insulin resistance, diabetes, dyslipidemia, hypertension, and cardiovascular disease, where adipose tissue-secreted cytokines, that is, adipokines, have been implicated in these processes. Omentin is a novel adipokine preferentially produced by visceral adipose tissue with insulin-sensitizing effects, where circulating levels are decreased in insulin-resistant states, for example, obesity and diabetes. With respect to vascular biology, omentin causes vasodilatation of blood vessels and attenuates C-reactive protein-induced angiogenesis potentially via the nuclear factor B signaling pathway, a potent proinflammatory signaling pathway. Thus, omentin may have beneficial effects on the metabolic syndrome and could potentially be used as a biologic marker and/or pharmacologic agent in this respect.

Insulin and Metformin Regulate Circulating and Adipose Tissue Chemerin

OBJECTIVE To assess chemerin levels and regulation in sera and adipose tissue from women with polycystic ovary syndrome (PCOS) and matched control subjects. RESEARCH DESIGN AND METHODS Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of chemerin. Serum chemerin was measured by enzyme-linked immunosorbent assay. We investigated the in vivo effects of insulin on serum chemerin levels via a prolonged insulin-glucose infusion. Ex vivo effects of insulin, metformin, and steroid hormones on adipose tissue chemerin protein production and secretion into conditioned media were assessed by Western blotting and enzyme-linked immunosorbent assay, respectively. RESULTS Serum chemerin, subcutaneous, and omental adipose tissue chemerin were significantly higher in women with PCOS (n = 14; P < 0.05, P < 0.01). Hyperinsulinemic induction in human subjects significantly increased serum chemerin levels (n = 6; P < 0.05, P < 0.01). In adipose tissue explants, insulin significantly increased (n = 6; P < 0.05, P < 0.01) whereas metformin significantly decreased (n = 6; P < 0.05, P < 0.01) chemerin protein production and secretion into conditioned media, respectively. After 6 months of metformin treatment, there was a significant decrease in serum chemerin (n = 21; P < 0.01). Importantly, changes in homeostasis model assessment–insulin resistance were predictive of changes in serum chemerin (P = 0.046). CONCLUSIONS Serum and adipose tissue chemerin levels are increased in women with PCOS and are upregulated by insulin. Metformin treatment decreases serum chemerin in these women.

Metformin Decreases the Adipokine Vaspin in Overweight Women With Polycystic Ovary Syndrome Concomitant With Improvement in Insulin Sensitivity and a Decrease in Insulin Resistance

OBJECTIVE—Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Vaspin (visceral adipose tissue–derived serine protease inhibitor) levels increase with hyperinsulinemia and obesity. Currently, no data exists on vaspin in PCOS women. We therefore assessed mRNA and protein levels of vaspin, including circulating vaspin, from subcutaneous and omental adipose tissue of PCOS women and matched control subjects. Ex vivo regulation of adipose tissue vaspin and the effects of metformin treatment on circulating vaspin levels in PCOS subjects were also studied. RESEARCH DESIGN AND METHODS—Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of vaspin. Serum vaspin was quantified by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue vaspin were analyzed ex vivo. RESULTS—There were significantly higher levels of circulating vaspin (P < 0.05), vaspin mRNA (P < 0.05), and protein (P < 0.05) in omental adipose tissue of PCOS women. Interestingly, in omental adipose tissue explants, glucose significantly increased vaspin protein levels and secretion into conditioned media (P < 0.001). Also, after 6 months of metformin treatment, there was a significant decrease in serum vaspin levels in PCOS women (P < 0.001). Furthermore, multivariate regression analysis revealed that following metformin therapy, changes in circulating glucose levels were predictive of changes in serum vaspin levels (P = 0.014). CONCLUSIONS—We report, for the first time, elevated serum and omental adipose tissue levels of vaspin in overweight PCOS women and ex vivo regulation of vaspin, predominantly by glucose. More importantly, metformin treatment decreases serum vaspin levels, a novel observation.

Nuclear Factor-κB Induction by Visfatin in Human Vascular Endothelial Cells: Its role in MMP-2/9 production and activation

OBJECTIVE—Visfatin is elevated in obesity and type 2 diabetes and is thought to be an inflammatory mediator within atherosclerotic lesions and to induce gelatinase activity. We investigated the activation of nuclear factor-κB (NF-κB), a well-known proinflammatory transcription factor, by visfatin in endothelial cells. RESEARCH DESIGN AND METHODS—Human endothelial cells were transfected with pNF-κB-Luc plasmid. Using quantitative PCR, Western blot analysis, and gelatin zymography, we studied NF-κB signaling in gelatinase-mediated vascular inflammation by visfatin using the NF-κB inhibitor BAY 11-7085. RESULTS—Visfatin significantly increased NF-κB transcriptional activity (P < 0.001). We also found a significant inhibition of tumor necrosis factor-α (TNF-α)-induced NF-κB activity by visfatin (P < 0.001). Furthermore, the NF-κB inhibitor significantly negated visfatin-induced matrix metalloproteinase (MMP)-2/9 mRNA expression, protein levels, and gelatinolytic activity (P < 0.001). CONCLUSIONS—Visfatin-induced NF-κB signaling in human endothelial cells affects the activation of gelatinases MMP-2 and -9, suggesting an important role of visfatin in the pathogenesis of vascular inflammation in obesity and type 2 diabetes.OBJECTIVE Visfatin is elevated in obesity and type 2 diabetes and is thought to be an inflammatory mediator within atherosclerotic lesions and to induce gelatinase activity. We investigated the activation of nuclear factor-kappaB (NF-kappaB), a well-known proinflammatory transcription factor, by visfatin in endothelial cells. RESEARCH DESIGN AND METHODS Human endothelial cells were transfected with pNF-kappaB-Luc plasmid. Using quantitative PCR, Western blot analysis, and gelatin zymography, we studied NF-kappaB signaling in gelatinase-mediated vascular inflammation by visfatin using the NF-kappaB inhibitor BAY 11-7085. RESULTS Visfatin significantly increased NF-kappaB transcriptional activity (P < 0.001). We also found a significant inhibition of tumor necrosis factor-alpha (TNF-alpha)-induced NF-kappaB activity by visfatin (P < 0.001). Furthermore, the NF-kappaB inhibitor significantly negated visfatin-induced matrix metalloproteinase (MMP)-2/9 mRNA expression, protein levels, and gelatinolytic activity (P < 0.001). CONCLUSIONS Visfatin-induced NF-kappaB signaling in human endothelial cells affects the activation of gelatinases MMP-2 and -9, suggesting an important role of visfatin in the pathogenesis of vascular inflammation in obesity and type 2 diabetes.

Metformin Treatment Exerts Antiinvasive and Antimetastatic Effects in Human Endometrial Carcinoma Cells

CONTEXT Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women associated with an increased risk of endometrial hyperplasia. We sought to study the effects of metformin treatment (widely used in the management of PCOS women) on human endometrial adenocarcinoma cells. OBJECTIVES To study the effects of metformin treatment on in vitro invasion and metastasis in human endometrial adenocarcinoma cells. Also, given the link between inflammation with endometrial cancer invasion and metastasis, we explored the roles of nuclear factor-κB (NF-κB), matrix metalloproteinases (MMPs) as well as v-akt murine thymoma viral oncogene homolog 1 (Akt) and extracellular signal-regulated kinases (Erk(1/2)) signaling pathways. DESIGN Sera were obtained from PCOS and control subjects. In vitro invasion were assessed in human endometrial cells (ECC-1 cells) by wound-healing motility and migration assays. NF-κB was studied by stably transfecting ECC-1 cells with a cis-reporter plasmid containing luciferase reporter gene linked to five repeats of NF-κB binding sites. The gelatinolytic activities of secreted MMP-2/9 in conditioned media were measured by gelatin zymography. Akt and Erk(1/2) phosphorylation were assessed by Western blotting. RESULTS In vitro invasion in ECC-1 cells was significantly attenuated by sera from PCOS women after 6 months of metformin treatment (850 mg twice daily) compared to matched controls (P < 0.01). These effects appear to be associated with NF-κB, MMP-2/9, as well as Akt and Erk(1/2) pathways that are known to be important regulators of inflammation, tumor invasion and metastasis. CONCLUSIONS Metformin, potentially, may serve as adjuvant treatment in the management of patients with endometrial cancer.

Metformin Treatment May Increase Omentin-1 Levels in Women With Polycystic Ovary Syndrome

OBJECTIVE Polycystic ovary syndrome (PCOS) is associated with the metabolic syndrome. Decreased omentin-1 levels are associated with obesity and diabetes. To study the effects of metformin treatment on omentin-1 levels in PCOS subjects and effects of omentin-1 on in vitro migration and angiogenesis. RESEARCH DESIGN AND METHODS Serum omentin-1 was measured by ELISA. Angiogenesis was assessed by studying capillary tube formation in human microvascular endothelial cells (HMEC-1) on growth factor reduced Matrigel. Endothelial cell migration assay was performed in a modified Boyden chamber. Nuclear factor-κB (NF-κB) was studied by stably transfecting HMEC-1 cells with a cis-reporter plasmid containing luciferase reporter gene linked to five repeats of NF-κB binding sites. Akt phosphorylation was assessed by Western blotting. RESULTS Serum omentin-1 was significantly lower in PCOS women (P < 0.05). After 6 months of metformin treatment, there was a significant increase in serum omentin-1 (P < 0.01). Importantly, changes in hs-CRP were significantly negatively correlated with changes in serum omentin-1 (P = 0.036). In vitro migration and angiogenesis were significantly increased in serum from PCOS women (P < 0.01) compared with matched control subjects; these effects were significantly attenuated by metformin treatment (P < 0.01) plausibly through the regulation of omentin-1 levels via NF-κB and Akt pathways. CRP and VEGF induced in vitro migration, and angiogenesis was significantly decreased by omentin-1. CONCLUSIONS Increases in omentin-1 levels may play a role but are not sufficient to explain the decreased inflammatory and angiogenic effects of sera from metformin-treated PCOS women.

Metformin decreases angiogenesis via NF-κB and Erk1/2/Erk5 pathways by increasing the antiangiogenic thrombospondin-1

AIMS Polycystic ovary syndrome (PCOS) is associated with insulin resistance (IR), obesity, and cardiovascular complications. Thrombospondin-1 (TSP-1) is a novel antiangiogenic adipokine highly expressed in obese insulin-resistant subjects. We sought to assess TSP-1 levels in adipose tissue (AT) from PCOS women and matched controls. The effects of metformin treatment on circulating TSP-1 levels in PCOS subjects, the effects of serum from normal and PCOS women on in vitro migration and angiogenesis before and after metformin treatment, and ex vivo regulation of AT TSP-1 by D-glucose were also studied. METHODS AND RESULTS Serum TSP-1 (ELISA), subcutaneous and omental AT TSP-1 mRNA (reverse transcriptase-polymerase chain reaction), and protein (western blotting) were significantly lower in PCOS women (P < 0.05). Corresponding plasminogen activator inhibitor-1 (PAI-1) and PAI-1 activity were significantly higher (P < 0.01). After 6 months of metformin treatment, there was a significant increase in serum TSP-1 (P < 0.05) and a corresponding decrease in PAI-1 and PAI-1 activity (P < 0.01). In vitro migration and angiogenesis were significantly increased in serum from PCOS women (P < 0.01); these effects were significantly attenuated by metformin treatment (P < 0.01) through the regulation of TSP-1 levels via nuclear factor-kappaB (NF-kappaB), extracellular regulated-signal kinase 1/2 (Erk1/2) and Erk5 pathways. Importantly, changes in the intima media thickness were predictive of changes in serum TSP-1 (P = 0.049). In AT explants, glucose significantly decreased TSP-1 protein production and secretion into conditioned media (ELISA) (P < 0.05, P < 0.001). CONCLUSION TSP-1 levels are lower in PCOS women. Metformin treatment increases serum TSP-1 in these women. Our findings provide novel insights into the relationship between obesity, IR, and angiogenesis.

Pre-B cell colony enhancing factor (PBEF)/visfatin induces secretion of MCP-1 in human endothelial cells: Role in visfatin-induced angiogenesis

OBJECTIVES Visfatin and Monocyte-Chemoattractant-Protein-1 (MCP-1) are elevated in cardiovascular pathologies, insulin-resistant and diabetic states. Visfatin has been reported to exhibit pro-angiogenic actions in human endothelial cells. Given MCP-1s well described pro-angiogenic properties we sought to study the potential interaction between visfatin and MCP-1 in human endothelial cells. We also explored the possible autocrine/paracrine mechanisms governing this potential interaction; specifically we looked at the effect of visfatin on MCP-1s putative receptor (CCR2 receptor) in human endothelial cells. METHODS AND RESULTS Using in vitro angiogenic assays (capillary tube formation and migration), Western blotting and RT-PCR, we found that visfatin, dose-dependently, induced MCP-1 as well as CCR2 levels. We also studied the involvement of PI3Kinase, MAPKinase and NF-kappaB pathways in visfatin induced MCP-1/CCR2 levels by employing LY294002, U0126 and BAY11-7085, respectively. We found the increase in MCP-1 and CCR2 levels by visfatin were negated by LY294002 and BAY11-7085, but not with U0126, suggesting the crucial role of PI3Kinase and NF-kappaB pathways in visfatin induced MCP-1 and its autocrine regulation via the CCR2 receptor. Finally, we consolidate the role of MCP-1 in visfatin-induced angiogenesis by employing CCR2 antagonist (RS-102895) and MCP-1 neutralising antibody, respectively. CONCLUSIONS Our novel data reveal that MCP-1 is pivotal in modulating visfatin-induced angiogenesis via NF-kappaB and PI3Kinase pathways. Furthermore, our findings elucidate the potential influence of autocrine/paracrine mechanisms (via the CCR2 receptor) underlying visfatins angiogenic effects through MCP-1.