No abstract

Alterations within the renal renin angiotensin system play a pivotal role in the development and progression of cardiovascular and renal disease. Angiotensin converting enzyme 2 (ACE2) is highly expressed in renal tubules and has been shown to be renoprotective in diabetes. The protease, a disintegrin and metalloprotease (ADAM) 17, is involved in the ectodomain shedding of several transmembrane proteins including ACE2. Renal ACE2 and ADAM17 were significantly increased in db/db mice compared to controls. We investigated the effect of the insulin sensitizer, rosiglitazone, on albuminuria, renal ADAM17 protein expression and ACE2 shedding in db/db diabetic mice. Rosiglitazone treatment of db/db mice normalized hyperglycemia, attenuated renal injury and decreased urinary ACE2 and renal ADAM17 protein expression. Urinary excreted ACE2 is enzymatically active. Western blot analysis of urinary ACE2 demonstrated two prominent immunoreactive bands at approximately 70 & 90 kDa. The predominant immunoreactive band is approximately 20 kDa shorter than the one demonstrated for kidney lysate, indicating possible ectodomain shedding of active renal ACE2 in the urine. Therefore, it is tempting to speculate that renoprotection of rosiglitazone could be partially mediated via downregulation of renal ADAM17 and ACE2 shedding. In addition, there was a positive correlation between blood glucose, urinary albumin, plasma glucagon, and triglyceride levels with urinary ACE2 excretion. In conclusion, urinary ACE2 could be used as a sensitive biomarker of diabetic nephropathy and for monitoring the effectiveness of renoprotective medication.

Background Asthma is a complex disorder influenced by genetics and the environment. Recent findings have linked abnormal DNA methylation in T cells with asthma; however, the potential dysregulation of methylation in airway epithelial cells is unknown. Studies of mouse models of asthma have observed greater levels of 5-hydoxymethylcytosine (5-hmC) and TET1 expression in lungs. TET proteins are known to catalyze methylation through modification of 5-mC to 5-hydroxymethylcytosine (5-hmC). Objective Associations between TET1 methylation and asthma and traffic-related air pollution were examined. Methods TET1 methylation levels from DNA derived from nasal airway epithelial cells collected from 12 African-American children with physician-diagnosed asthma and their non-asthmatic siblings were measured using Illumina 450K arrays. Regions of interest were verified by locus-specific pyrosequencing in 35 additional sibling pairs and replicated in an independent population (N=186). Exposure to traffic-related air pollution (TRAP) at participants’ early life and current home addresses was estimated using a land-use regression model. Methylation studies in saliva, PBMCs, and human bronchial epithelial cells (HBEC) were done to support our findings. Results Loss of methylation at a single CpG site in the TET1 promoter (cg23602092) and increased global 5hmC was significantly associated with asthma. In contrast, TRAP exposure at participants’ current homes significantly increased methylation at the same site. Patterns were consistent across tissue sample types. 5-aza-2'-deoxycytidine and diesel exhaust particle exposure in HBEC was associated with altered TET1 methylation, expression and global 5-hmC. Conclusions Our findings suggest a possible role of TET1 methylation in asthma and response to TRAP. Capsule summary TET1 DNA methylation might serve as a biomarker for asthma and higher risk of exposure-related asthma exacerbations.

BackgroundDendritic cells (DCs) are important mediators of innate and adaptive immune responses, but the gene networks governing their lineage differentiation and maturation are poorly understood. To gain insight into the mechanisms that promote human DC differentiation and contribute to the acquisition of their functional phenotypes, we performed genome-wide base-resolution mapping of 5-methylcytosine in purified monocytes and in monocyte-derived immature and mature DCs.ResultsDC development and maturation were associated with a great loss of DNA methylation across many regions, most of which occurs at predicted enhancers and binding sites for known transcription factors affiliated with DC lineage specification and response to immune stimuli. In addition, we discovered novel genes that may contribute to DC differentiation and maturation. Interestingly, many genes close to demethylated CG sites were upregulated in expression. We observed dynamic changes in the expression of TET2, DNMT1, DNMT3A and DNMT3B coupled with temporal locus-specific demethylation, providing possible mechanisms accounting for the dramatic loss in DNA methylation.ConclusionsOur study is the first to map DNA methylation changes during human DC differentiation and maturation in purified cell populations and will greatly enhance the understanding of DC development and maturation and aid in the development of more efficacious DC-based therapeutic strategies.

Angiotensin II (Ang II) is involved in induction and progression of renal damage in diabetes. Angiotensin converting enzyme 2 (ACE2) is highly expressed in the kidney and has been shown to be renoprotective by degrading Ang II to Ang-(1–7). Disintegrin and Metalloproteinase (ADAM) 17 mediated shedding of renal ACE2 contribute to diabetic nephropathy pathogenesis. Lifestyle modification and metformin are recommended as initial therapies for most patients with type 2 diabetes. The aim of the study was to investigate whether exercise training and/or metformin improve glucose homeostasis, albuminuria and downregulate renal ADAM17 and ACE2 shedding in db/db mice. Seven wk old normal and db/db mice were subjected either to sedentary or exercise training with and without metformin (150 mg/kg/day) for 10 wks. Exercise training significantly lowered blood glucose, urinary albumin and ACE2 excretion in db/db mice. ADAM17 and ACE2 proteins were co-localized in cortical tubules of the kidney, suggesting a possible interaction. Metformin treatment was effective in lowering hyperglycemia only during the first 2 weeks of treatment. Increased renal ADAM17 in 17 wk old db/db mice was corrected by physical exercise but not metformin. In addition, exercise training reduced plasma triglycerides and enhanced insulin levels of db/db mice. In conclusion, exercise training alone and in combination with metformin prevented shedding of renal ACE2 by decreasing ADAM17 protein. Urinary ACE2 could serve as a prognostic tool in the progression of kidney damage and its attenuation by exercise may partially contribute to its renal protection.