A synthetic anti-inflammatory sterol improves insulin sensitivity in insulin-resistant obese impaired glucose tolerance subjects.

OBJECTIVE: To study the activity of HE3286 (17α-ethynylandrost-5-ene-3ß,7ß,17ß-triol), an anti-inflammatory sterol that is active in models of obesity-induced inflammation and insulin resistance in high body mass index (BMI) subjects with impaired glucose tolerance (IGT). DESIGN AND METHODS: HE3286 was explored in high BMI IGT subjects using hyperinsulinemic, euglycemic clamp studies. RESULTS: In insulin-resistant subjects, HE3286 significantly increased day 29 insulin-stimulated glucose disposal and HDL cholesterol, and decreased C-reactive protein (CRP) compared to placebo. For HE3286, change in M value showed a significant negative correlation with baseline M value. Subjects with baseline M value below the median (4.2 mg/kg/min) had significantly lower adiponectin and higher lipopolysaccharide-stimulated peripheral blood mononuclear cell cytokine secretion. After 28 days of HE3286 treatment, adiponectin levels were significantly increased in insulin-resistant (baseline M < 4.2), but not insulin-sensitive (baseline M > 4.2) subjects, compared to placebo. CONCLUSIONS: HE3286 significantly increased the frequency of subjects with increased insulin-stimulated glucose disposal and HDL, and decreased CRP compared to placebo, in insulin-resistant, but not insulin-sensitive subjects. Thus, HE3286 may preferentially benefit insulin-resistant, inflamed, high BMI IGT subjects.

An anti-inflammatory sterol decreases obesity-related inflammation-induced insulin resistance and metabolic dysregulation.

Obesity-related inflammation-induced insulin resistance and metabolic dysregulation were investigated in retrospective analysis of placebo hematologic and metabolic laboratory data from trials associated with increasing chronic low-grade inflammation and body mass index. Studies included healthy subjects and those with progressive stages of metabolic dysregulation, including type 2 diabetes mellitus with uncontrolled hemoglobin A1c. Intrasubject variances in erythroid and metabolic values increased with metabolic dysregulation. Random effects were demonstrated in treatment-naïve diabetes for erythroid, glucose, and HbA1c fluctuations. The anti-inflammatory insulin sensitizer, HE3286, was tested for its ability to decrease obesity-related inflammation-induced insulin resistance and metabolic dysregulation in diabetes. HE3286 significantly decreased erythroid and metabolic variances and improved 1,5-anhydroglucitol (a surrogate of postprandial glucose) compared to the placebo group. HE3286 HbA1c decrease correlated with weight loss and inversely with baseline monocyte chemoattractant protein-1 (MCP-1) in metformin-treated diabetics. Normalization of HbA1c to the 84-day average hemoglobin revealed that HE3286 HbA1c decrease correlated with high baseline MCP-1 and MCP-1 decrease in treatment-naïve diabetics. HE3286 decreased insulin resistance, increased the frequency of decreased day 84 HbA1c in metformin-treated subjects, and decreased day 112 HbA1c in treatment-naïve diabetics. HE3286 may be useful to restore metabolic homeostasis in type 2 diabetes.

5-androstenediol ameliorates pleurisy, septic shock, and experimental autoimmune encephalomyelitis in mice.

Androstenediol (androst-5-ene-3ß,17ß-diol; 5-AED), a natural adrenal steroid, has been shown to suppress experimental autoimmune encephalomyelitis (EAE) in female SJL/J mice. We here report that 5-AED limits inflammation and proinflammatory cytokines including TNFα in murine models of carrageenan-induced pleurisy and lippopolysaccaride- (LPS) induced septic shock. 5-AED binds to and transactivates sex steroid receptors with the same general rank order of potency (ERß > ERα ≫ AR). 5-AED provides benefit in EAE in a dose-dependent fashion, even when treatment is delayed until onset of disease. The minimally effective dose may be as low as 4 mg/kg in mice. However, benefit was not observed when 5-AED was given in soluble formulation, leading to a short half-life and rapid clearance. These observations suggest that treatment with 5-AED limits the production of pro-inflammatory cytokines in these animal models and, ultimately, when formulated and administered properly, may be beneficial for patients with multiple sclerosis and other Th1-driven autoimmune diseases.

A new antidiabetic compound attenuates inflammation and insulin resistance in Zucker diabetic fatty rats.

Tissue macrophage inflammatory pathways contribute to obesity-associated insulin resistance. Here, we have examined the efficacy and mechanisms of action of a novel anti-inflammatory compound (HE3286) in vitro and in vivo. In primary murine macrophages, HE3286 attenuates LPS- and TNFalpha-stimulated inflammation. In Zucker diabetic fatty rats, inflammatory cytokine/chemokine expression was downregulated in liver and adipose tissue by HE3286 treatment, as was macrophage infiltration into adipose tissue. In line with reduced inflammation, HE3286 treatment normalized fasting and fed glucose levels, improved glucose tolerance, and enhanced skeletal muscle and liver insulin sensitivity, as assessed by hyperinsulinemic euglycemic clamp studies. In phase 2 clinical trials, HE3286 treatment led to an enhancement in insulin sensitivity in humans. Gluconeogenic capacity was also reduced by HE3286 treatment, as evidenced by a reduced glycemic response during pyruvate tolerance tests and decreased basal hepatic glucose production (HGP) rates. Since serum levels of gluconeogenic substrates were decreased by HE3286, it indicates that the reduction of both intrinsic gluconeogenic capacity and substrate availability contributes to the decrease in HGP. Lipidomic analysis revealed that HE3286 treatment reduced liver cholesterol and triglyceride content, leading to a feedback elevation of LDL receptor and HMG-CoA reductase expression. Accordingly, HE3286 treatment markedly decreased total serum cholesterol. In conclusion, HE3286 is a novel anti-inflammatory compound, which displays both glucose-lowering and cholesterol-lowering effects.

Amelioration of glucose intolerance by the synthetic androstene HE3286: link to inflammatory pathways.

Insulin resistance, the major metabolic abnormality underlying type 2 diabetes, is associated with chronic inflammation and heavy macrophage infiltration in white adipose tissue (WAT). The therapeutic properties of the synthetic adrenal steroid Delta(5)-androstene-17alpha-ethynyl-3beta,7beta,17beta-triol (HE3286) were characterized in metabolic disease models. Treatment of diabetic db/db mice with HE3286 suppressed progression to hyperglycemia and markedly improved glucose clearance. Similar effects were also observed in insulin-resistant, diet-induced obese C57BL/6J mice and genetically obese ob/ob mice. This effect appeared to be a consequence of reduced insulin resistance because HE3286 lowered blood insulin levels in db/db and ob/ob mice. Treatment with HE3286 was accompanied by suppressed expression of the prototype macrophage-attracting chemokine monocyte chemoattractant protein-1 in WAT, along with its cognate receptor C-C motif chemokine receptor-2. Exposure of mouse macrophages to HE3286 in vitro caused partial suppression of endotoxin (lipopolysaccharide)-induced nuclear factor kappa-B (NF-kappaB)-sensitive reporter gene expression, NF-kappaB nuclear translocation, and NF-kappaB/p65 serine phosphorylation. Proinflammatory kinases, including IkappaB kinase, c-Jun NH2-terminal kinase, and p38, were also inhibited by HE3286. In ligand competition experiments HE3286 did not bind to classical sex steroid or corticosteroid receptors, including androgen receptor (AR), progesterone receptor, estrogen receptor (ER) alpha or ERbeta, and glucocorticoid receptor (GR). Likewise, in cells expressing nuclear receptor-sensitive reporter genes HE3286 did not substantially stimulate transactivation of AR, ER, GR, or peroxisome proliferator-activated receptor (PPAR) alpha, PPARdelta, and PPARgamma. These findings indicate that HE3286 improves glucose homeostasis in diabetic and insulin-resistant mice and suggest that the observed therapeutic effects result from attenuation of proinflammatory pathways, independent of classic sex steroid receptors, corticosteroid receptors, or PPARs.

Leptin is an autocrine/paracrine regulator of wound healing.

Leptin, a 16 kDa pleiotropic cytokine primarily expressed in adipose tissue, has been shown to cause multiple systemic biological actions. Recently, leptin has also been documented as an important component of the wound healing process and its receptor appears to be expressed in wound tissue. We have previously demonstrated that leptin is a potent angiogenic factor exerting direct effects on endothelial cells and that transcription of its encoding gene is regulated by hypoxia. Here, we hypothesize that leptin expression is acutely up-regulated in the ischemic tissue of experimental wounds. Using a combination of in situ hybridization and quantitative RT-PCR experiments, we show that leptin expression is rapidly and steadily up-regulated in skin tissue from incisional and excisional wounds. By immunohistochemistry, we demonstrate increased and sustained leptin protein levels in basal keratinocytes, blood vessel walls, and fibroblasts. To determine whether leptin is required for normal healing, excisional wounds were treated with neutralizing anti-leptin antibodies. This treatment markedly hampered healing progression and prevented wound closure and contraction. Finally, a transient rise in circulating blood leptin levels was detected within the first 24 h after inflicting the injury; we present evidence suggesting that this elevation is due to increased leptin production at the ischemic wound site. We conclude that leptin is acutely up-regulated in the injured skin and propose that this local production of leptin serves a critical functional role as an autocrine/paracrine regulator of normal wound healing.

Transcriptional activation of the human leptin gene in response to hypoxia. Involvement of hypoxia-inducible factor 1.

In addition to having a major role in energy homeostasis, leptin is emerging as a pleiotropic cytokine with multiple physiological effector functions. The recently discovered proangiogenic activity of leptin suggested the hypothesis that its production might be regulated by hypoxia, as are other angiogenic factors. To examine this proposal, the expression of leptin protein and mRNA was measured and found to be markedly up-regulated in response to ambient or chemical hypoxia (upon exposure to desferrioxamine or cobalt chloride), an effect that requires intact RNA synthesis, suggesting a transcriptional mechanism. Transient transfection of cultured cells with deletion constructs of the leptin gene promoter linked to a reporter gene revealed a functional hypoxia response element (HRE) located at position -116 within the proximal upstream region. This putative HRE harbors a characteristic 5'-RCGTG-3' core motif, a hallmark of hypoxia-sensitive genes and recognized by the hypoxia-inducible factor 1 (HIF1), which consists of a HIF1alpha/HIFbeta heterodimer. Constructs harboring this -116/HRE supported reporter gene expression in response to hypoxia but not when mutated. Expression of HIF1alpha cDNA in normoxic cells mimicked hypoxia-induced reporter gene expression in cells cotransfected with the wild type leptin -116/HRE construct but not with the mutant. Gel shift assays with a (32)P-labeled leptin promoter -116/HRE probe and nuclear extracts from hypoxia-treated cells indicated binding of the HIF1alpha/beta heterodimer, which was blocked with an excess of unlabeled -116/HRE probe or a HIF1-binding probe from the erythropoietin gene enhancer. Taken together, these observations demonstrate that the leptin gene is actively engaged by hypoxia through a transcriptional pathway commonly utilized by hypoxia-sensitive genes.