Adiponectin is an adipose tissue-specific protein that is abundantly present in the circulation and suggested to be involved in insulin sensitivity and development of atherosclerosis. Because cytokines are suggested to regulate adiponectin, the aim of the present study was to investigate the interaction between adiponectin and three adipose tissue-derived cytokines (IL-6, IL-8, and TNF-alpha). The study was divided into three substudies as follows: 1) plasma adiponectin and mRNA levels in adipose tissue biopsies from obese subjects [mean body mass index (BMI): 39.7 kg/m2, n = 6] before and after weight loss; 2) plasma adiponectin in obese men (mean BMI: 38.7 kg/m2, n = 19) compared with lean men (mean BMI: 23.4 kg/m2, n = 10) before and after weight loss; and 3) in vitro direct effects of IL-6, IL-8, and TNF-alpha on adiponectin mRNA levels in adipose tissue cultures. The results were that 1) weight loss resulted in a 51% (P < 0.05) increase in plasma adiponectin and a 45% (P < 0.05) increase in adipose tissue mRNA levels; 2) plasma adiponectin was 53% (P < 0.01) higher in lean compared with obese men, and plasma adiponectin was inversely correlated with adiposity, insulin sensitivity, and IL-6; and 3) TNF-alpha (P < 0.01) and IL-6 plus its soluble receptor (P < 0.05) decreased adiponectin mRNA levels in vitro. The inverse relationship between plasma adiponectin and cytokines in vivo and the cytokine-induced reduction in adiponectin mRNA in vitro suggests that endogenous cytokines may inhibit adiponectin. This could be of importance for the association between cytokines (e.g., IL-6) and insulin resistance and atherosclerosis.

Adiponectin is a novel adipocyte-specific protein, which, it has been suggested, plays a role in the development of insulin resistance and atherosclerosis. Although it circulates in high concentrations, adiponectin levels are lower in obese subjects than in lean subjects. Apart from negative correlations with measures of adiposity, adiponectin levels are also reduced in association with insulin resistance and type 2 diabetes. Visceral adiposity has been shown to be an independent negative predictor of adiponectin. Thus, most features of the metabolic syndrome's negative associations with adiponectin have been shown. Adiponectin levels seem to be reduced prior to the development of type 2 diabetes, and administration of adiponectin has been accompanied by lower plasma glucose levels as well as increased insulin sensitivity. Furthermore, reduced expression of adiponectin has been associated with some degree of insulin resistance in animal studies indicating a role for hypoadiponectinaemia in relation to insulin resistance. The primary mechanisms by which adiponectin enhance insulin sensitivity appears to be through increased fatty acid oxidation and inhibition of hepatic glucose production. Adiponectin levels are increased by thiazoledinedione treatment, and this effect might be important for the enhanced insulin sensitivity induced by thiazolidinediones. In contrast, adiponectin levels are reduced by pro-inflammatory cytokines especially tumour necrosis factor-alpha. In summary, adiponectin in addition to possible anti-inflammatory and anti-atherogenic effects appears to be an insulin enhancer, with potential as a new pharmacologic treatment modality of the metabolic syndrome and type 2 diabetes.

MCP-1 is correlated with specific macrophage markers, adiposity, and AT localization, but the relationship seems to be related to the number of AT-resident macrophages. Despite this, MCP-1 may be involved in obesity-related health complications, and the decrease of MCP-1 by metformin and thiazolidinediones suggests that these antidiabetic compounds have antiinflammatory properties improving the low-grade inflammatory state observed in obesity.

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This study evaluated the long-term safety and efficacy of dapagliflozin as an adjunct to adjustable insulin in patients with type 1 diabetes and inadequate glycemic control. RESEARCH DESIGN AND METHODS DEPICT-1 (Dapagliflozin Evaluation in Patients With Inadequately Controlled Type 1 Diabetes) was a randomized (1:1:1), double-blind, placebo-controlled phase 3 study of dapagliflozin 5 mg and 10 mg in patients with type 1 diabetes (HbA 1c 7.5-10.5% [58-91 mmol/mol]) (NCT02268214). The results of the 52-week study, consisting of the 24-week short-term and 28-week extension period, are reported here. RESULTS Of the 833 patients randomized into the study, 708 (85%) completed the 52-week study. Over 52 weeks, dapagliflozin 5 mg and 10 mg led to clinically significant reductions in HbA 1c (difference vs. placebo [95% CI] 20.

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Human immunodeficiency virus (HIV)-associated lipodystrophy syndrome (HALS) is a side effect of highly active antiretroviral therapy of HIV-infected patients; however, the mechanism of the lipodystrophy and insulin resistance seen in this syndrome remains elusive. Adiponectin, an adipocyte-specific protein, is thought to play an important role in regulating insulin sensitivity. We investigated circulating levels and gene expression of adiponectin in subcutaneous abdominal adipose tissue (AT) from 18 HIV-infected patients with HALS compared with 18 HIV-infected patients without HALS. Implications of cytokines for adiponectin levels were investigated by determining circulating levels of TNF-α, IL-6, and IL-8 as well as gene expression of these cytokines in AT. HALS patients exhibited 40% reduced plasma adiponectin levels ( P < 0.05) compared with non-HALS subjects. Correspondingly, adiponectin mRNA levels in AT were reduced by >50% ( P = 0.06). HALS patients were insulin resistant, and a positive correlation was found between plasma adiponectin and insulin sensitivity ( r = 0.55, P < 0.01) and percent limb fat ( r = 0.61, P < 0.01). AT mRNA of TNF-α, IL-6, and IL-8 was increased in AT of HALS subjects ( P < 0.05), and both AT TNF-α mRNA and plasma TNF-α were negatively correlated to plasma adiponectin ( P < 0.05). Finally, TNF-α was found in vitro to inhibit human AT adiponectin mRNA by 80% ( P < 0.05). In conclusion, HALS patients have reduced levels of plasma adiponectin and adiponectin mRNA in AT. Increased cytokine mRNA in AT is hypothesized to exert an inhibitory effect on adiponectin gene expression and, consequently, to play a role in the reduced plasma adiponectin levels found in HALS patients.

IL-8 is released from human adipose tissue. Circulating IL-8 is increased in obese compared with lean subjects and is associated with measures of insulin resistance, development of atherosclerosis, and cardiovascular disease. We studied 1) the production and release of IL-8 in vitro from paired samples of subcutaneous (SAT) and visceral (VAT) adipose tissue and 2) the production of IL-8 from whole adipose tissue, isolated adipocytes, and nonfat cells of adipose tissue. IL-8 release from VAT was fourfold higher than from SAT ( P < 0.05), and IL-8 mRNA was twofold higher in VAT compared with SAT ( P < 0.01). Dexamethasone (50 nM) attenuated IL-8 production by 50% ( P < 0.05), and IL-1β (2 μg/l) increased IL-8 production up to 15-fold ( P < 0.001). IL-8 release from whole SAT explants correlated with body mass index (BMI; r = 0.78; P < 0.001), as did IL-8 release from nonfat cells ( r = 0.79; P < 0.001). However, no correlation was found between IL-8 release from the fraction of isolated adipocytes and BMI ( r = 0.01). In conclusion, we demonstrated an increased release of IL-8 from VAT compared with SAT. Furthermore, our data suggest that the observed elevation in circulating levels of IL-8 in obese subjects is due primarily to the release of IL-8 from nonfat cells from adipose tissue. The high levels of IL-8 release from human adipose tissue and accumulation of this tissue in obese subjects may account for some of the increase in circulating IL-8 observed in obesity.