Metabolic Obesity Phenotypes and Risk of Cellulitis: A Cohort Study.

No cohort studies have evaluated the effect of obesity on the risk of cellulitis according to metabolic health status. We investigated an association of BMI and metabolic health status with the development of cellulitis. We conducted a cohort study of 171,322 Korean adults who underwent a health checkup examination and were followed from 2011 to 2016 for cellulitis and hospital admission related to cellulitis, which were ascertained through the linkage to the Health Insurance and Review Agency database. Being metabolically healthy was defined as not having any metabolic syndrome component and having a homeostasis model assessment of insulin resistance <2.5. During 638,240.4 person-years of follow-up, 14,672 cases of incident cellulitis were identified with 225 cases of cellulitis-related admission. After adjustment for possible confounders, the multivariable-adjusted hazard ratios (95% CI) for incident cellulitis comparing BMIs 23-24.9, 25-29.9, and ≥30 with a BMI of 18.5-22.9 kg/m2 as the reference were 1.07 (1.02-1.11), 1.09 (1.04-1.13), and 1.19 (1.08-1.31), respectively, whereas the corresponding multivariable-adjusted hazard ratios (95% CI) for cellulitis-related admission were 1.55 (1.05-2.3), 2.47 (1.73-3.53), and 4.8 (2.86-8.05), respectively. These associations were consistently observed in both metabolically healthy and unhealthy individuals with no significant interaction. In a large cohort of apparently healthy adults, increased BMI was associated with an increased risk of cellulitis and hospitalization for cellulitis in both metabolically healthy and unhealthy individuals. Obesity appears to be an independent risk factor for cellulitis regardless of metabolic phenotype.

Metformin normalizes type 2 diabetes-induced decrease in cell proliferation and neuroblast differentiation in the rat dentate gyrus.

In this study, we observed the effects of metformin, one of the most widely prescribed drugs for the treatment of type 2 diabetes, on cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG) in Zucker diabetic fatty (ZDF) rats, which are a model for type 2 diabetes. For this, metformin was administered orally once a day to 14-week-old ZDF rats for 2 weeks and the animals were sacrificed at 16 weeks of age. During this period, blood glucose levels were higher in the vehicle-treated ZDF rats than in the Zucker lean control (ZLC) rats. Metformin treatment significantly decreased the blood glucose levels from 15.5 weeks of age. In the SZDG, Ki67 (a marker for cell proliferation)- and doublecortin (DCX, a marker for differentiated neuroblasts)-immunoreactive cells were much lower in the vehicle-treated ZDF rats than in the ZLC rats. In the metformin-treated ZDF group, Ki67- and DCX-immunoreactive cells were significantly increased in the SZDG compared to those in the vehicle-treated ZDF group. These results suggest that diabetes significantly reduces cell proliferation and neuroblast differentiation in the SZDG and that metformin treatment normalizes the reduction of cell proliferation and neuroblast differentiation in the SZDG in diabetic rats.

STAT3 inhibits the degradation of HIF-1alpha by pVHL-mediated ubiquitination

Hypoxia-inducible factor 1alpha (HIF-1alpha) is rapidly degraded by the ubiquitin-proteasome pathway under normoxic conditions. Ubiquitination of HIF-1alpha is mediated by interaction with von Hippel-Lindau tumor suppressor protein (pVHL). In our previous report, we found that hypoxia-induced active signal transducer and activator of transcription3 (STAT3) accelerated the accumulation of HIF-1alpha protein and prolonged its half-life in solid tumor cells. However, its specific mechanisms are not fully understood. Thus, we examined the role of STAT3 in the mechanism of pVHL-mediated HIF-1alpha stability. We found that STAT3 interacts with C-terminal domain of HIF-1alpha and stabilizes HIF-1alpha by inhibition of pVHL binding to HIF-1alpha. The binding between HIF-1alpha and pVHL, negative regulator of HIF-1alpha stability, was interfered dose-dependently by overexpressed constitutive active STAT3. Moreover, we found that the enhanced HIF-1alpha protein levels by active STAT3 are due to decrease of poly-ubiquitination of HIF-1alpha protein via inhibition of interaction between pVHL and HIF-1alpha. Taken together, our results suggest that STAT3 decreases the pVHL-mediated ubiquitination of HIF-1alpha through competition with pVHL for binding to HIF-1alpha, and then stabilizes HIF-1alpha protein levels.

Anti-inflammatory effects of 8-hydroxydeoxyguanosine in LPS-induced microglia activation: suppression of STAT3-mediated intercellular adhesion molecule-1 expression

To elucidate the roles of 8-hydroxydeoxyguanosine (oh8dG), the nucleoside of 8-hydroxyguanine (oh8Gua), we examined the effects of oh8dG upon LPS-induced intercellular adhesion molecule-1 (ICAM-1) expression and the underlying mechanisms in brain microglial cells. We found that oh8dG reduces LPS-induced reactive oxygen species (ROS) production, STAT3 activation, and ICAM-1 expression. oh8dG also suppresses pro-inflammatory cytokines, such as TNF-alpha, IL-6 and IFN-gamma. Overexpression of dominant negative STAT3 completely diminshed STAT3-mediated ICAM-1 transcriptional activity. Chromatin immunoprecipitation studies revealed that oh8dG inhibited recruitment of STAT3 to the ICAM-1 promoter, followed by a decrease in ICAM-1 expression. Using mice lacking a functional Toll-like receptor 4 (TLR4), we demonstrated that, while TLR4+/+ microglia were activated by LPS, TLR4-/-microglia exhibited inactivated STAT3 in response to LPS. Evidently, LPS modulates STAT3-dependent ICAM-1 induction through TLR4-mdiated cellular responses. Oh8dG apparently plays a role in anti-inflammatory actions via suppression of ICAM-1 gene expression by blockade of the TLR4-STAT3 signal cascade in inflammation-enhanced brain microglia. Therefore, oh8dG in the cytosol probably functions as an anti-inflammatory molecule and should be considered as a candidate for development of anti-inflammatory agents.

Interleukin-7 Receptor is Indispensable for Proliferation and Survival in Thymic gamma sigma T Cell Development

BACKGROUND: Interleukin-7 receptor (IL-7R) alpha-deficient mice have small numbers of B cells and alpha beta T cells in periphery, they totally lack gamma sigma T cells. In addition, the V-J recombination and transcription of TCRgamma genes is also severely impaired in IL-7Ralpha-deficient mice. Stat5, a signaling molecule of the IL-7R, induces germline transcription in the TCRgamma locus, and promotes V-J recombination and gamma sigma T cell development. However, the roles for IL-7R signaling pathway in thymic or extrathymic gamma sigma T cell development are largely unknown. METHODS: To clarify the role of the IL-7 receptor in proliferation and survival of gamma sigma T cells, we introduced the TCR gamma sigma transgene, Vgamma2/ Vsigma5, into IL-7Ralpha-deficient mice, and investigated the development of gamma sigma T cells. RESULTS: We found that Vgamma2/Vsigma5 transgene restored gamma sigma T cells in the epithelium of the small intestine (IEL) but not in the thymus and the spleen. Further addition of a bcl-2 transgene resulted in partial recovery of gamma sigma T cells in the thymus and the spleen of these mice. CONCLUSION: Taken together, this study revealed that the IL-7Ralpha is indispensable for proliferation and survival mainly in thymic gamma sigma T cell development.