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A modest decrease in endothelial NOS in mice comparable to that associated with human NOS3 variants exacerbates diabetic nephropathy.

ABSTRACT: Polymorphisms in the human endothelial nitric oxide synthase (eNOS) gene (NOS3) have been associated with advanced nephropathy in diabetic patients and with decreased expression in tissue culture. However, direct proof that modest genetic decreases in eNOS expression worsen diabetic nephropathy is lacking. To investigate this effect, we took advantage of the hybrid vigor and genetic uniformity of the F1 progeny (eNOS(+/+), eNOS(+/-), or eNOS(-/-) with or without diabetes) of a cross between heterozygous 129S6/SvEvTac eNOS(+/-) inbred females and heterozygous C57BL/6J eNOS(+/-) inbred males carrying the dominant Akita diabetogenic mutation Ins2(C96Y/+). Whereas all C57BL/6J inbred eNOS(-/-) and eNOS(+/-) diabetic mice died before 5 mo, almost half of the F1 hybrid eNOS(-/-) and eNOS(+/-) diabetic mice lived until killed at 7 mo. Heterozygous eNOS(+/-) diabetic mice expressed ?35% eNOS mRNA in the kidney and ?25% glomerular eNOS protein relative to their eNOS(+/+) diabetic littermates. These decreases in eNOS elevated blood pressure (BP) but not blood glucose. Urinary albumin excretion, mesangial expansion, glomerulosclerosis, mesangiolysis, and glomerular filtration rate increased in the order: eNOS(+/+) Akita < eNOS(+/-) Akita < eNOS(-/-) Akita, independently of BP. Glomerular basement membrane thickening depended on increased BP. Renal expression of tissue factor and other inflammatory factors increased with the nephropathy; Nos2 also increased. Surprisingly, however, decreased eNOS expression ameliorated the increases in oxidative stress and tubulointerstitial fibrosis caused by diabetes. Our data demonstrate that a modest decrease in eNOS, comparable to that associated with human NOS3 variants, is sufficient to enhance diabetic nephropathy independently of its effects on BP.

SUBMITTER: Wang CH

PROVIDER: S-EPMC3033253 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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A modest decrease in endothelial NOS in mice comparable to that associated with human NOS3 variants exacerbates diabetic nephropathy.

Wang Chih-Hong CH Li Feng F Hiller Sylvia S Kim Hyung-Suk HS Maeda Nobuyo N Smithies Oliver O Takahashi Nobuyuki N

Proceedings of the National Academy of Sciences of the United States of America 20110118 5

Polymorphisms in the human endothelial nitric oxide synthase (eNOS) gene (NOS3) have been associated with advanced nephropathy in diabetic patients and with decreased expression in tissue culture. However, direct proof that modest genetic decreases in eNOS expression worsen diabetic nephropathy is lacking. To investigate this effect, we took advantage of the hybrid vigor and genetic uniformity of the F1 progeny (eNOS(+/+), eNOS(+/-), or eNOS(-/-) with or without diabetes) of a cross between hete ...[more]

PMID: 21245338

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Project description:Type 2 diabetes mellitus (T2DM) is associated with a high incidence of nephropathy. The aim of this study was to investigate the association of a genetic polymorphism of carnosinase (CNDP1-D18S880 and -rs2346061), endothelial nitric oxide synthase (NOS3-rs1799983), and manganese superoxide dismutase (MnSOD-rs4880) genes with the development of diabetic nephropathy among Malaysian type 2 diabetic patients. A case-control association study was performed using 652 T2DM patients comprising 227 Malays (without nephropathy = 96 and nephropathy = 131), 203 Chinese (without nephropathy = 95 and nephropathy = 108), and 222 Indians (without nephropathy = 136 and nephropathy = 86). DNA sequencing was performed for the D18S880 of CNDP1, while the rest were tested using DNA Sequenom MassARRAY to identify the polymorphisms. DNA was extracted from the secondary blood samples taken from the T2DM patients. The alleles and genotypes were tested using four genetic models, and the best mode of inheritance was chosen based on the least p value. The rs2346061 of CNDP1 was significantly associated with diabetic nephropathy among the Indians only with OR = 1.94 and 95% CI = (1.76-3.20) and fitted best the multiplicative model, while D18S880 was associated among all the three major races with the Malays having the strongest association with OR = 2.46 and 95% CI = (1.48-4.10), Chinese with OR = 2.26 and 95% CI = (1.34-3.83), and Indians with OR = 1.77 and 95% CI = (1.18-2.65) in the genotypic multiplicative model. The best mode of inheritance for both MnSOD and NOS3 was the additive model. For MnSOD-rs4880, the Chinese had OR = 2.8 and 95% CI = (0.53-14.94), Indians had OR = 2.4 and 95% CI = (0.69-2.84), and Malays had OR = 2.16 and 95% CI = (0.54-8.65), while for NOS3-rs1799983, the Indians had the highest risk with OR = 3.16 and 95% CI = (0.52-17.56), followed by the Chinese with OR = 3.55 and 95% CI = (0.36-35.03) and the Malays with OR = 2.89 and 95% CI = (0.29-28.32). The four oxidative stress-related polymorphisms have significant effects on the development of nephropathy in type 2 diabetes patients. The genes may, therefore, be considered as risk factors for Malaysian subjects who are predisposed to T2DM nephropathy.

Project description:BACKGROUND:Glomerular endothelium dysfunction, which plays a crucial role in the pathogenesis of early diabetic nephropathy, might be caused by circulating metabolic abnormalities. Platelet microparticles, extracellular vesicles released from activated platelets, have recently emerged as a novel regulator of vascular dysfunction. METHODS:We studied the effects of platelet microparticles on glomerular endothelial injury in early diabetic nephropathy in rats with streptozotocin-induced diabetes and primary rat glomerular endothelial cells. Isolated platelet microparticles were measured by flow cytometry. RESULTS:Plasma platelet microparticles were significantly increased in diabetic rats, an effect inhibited in aspirin-treated animals. In cultured glomerular endothelial cells, platelet microparticles induced production of reactive oxygen species, decreased nitric oxide levels, inhibited activities of endothelial nitric oxide synthase and SOD, increased permeability of the glomerular endothelium barrier, and reduced thickness of the endothelial surface layer. Conversely, inhibition of platelet microparticles in vivo by aspirin improved glomerular endothelial injury. Further analysis showed that platelet microparticles activated the mammalian target of rapamycin complex 1 (mTORC1) pathway in glomerular endothelial cells; inhibition of the mTORC1 pathway by rapamycin or raptor siRNA significantly protected against microparticle-induced glomerular endothelial injury in vivo and in vitro. Moreover, platelet microparticle-derived chemokine ligand 7 (CXCL7) contributed to glomerular endothelial injury, and antagonizing CXCL7 using CXCL7-neutralizing antibody or blocking CXCL7 receptors with a competitive inhibitor of CXCR1 and CXCR2 dramatically attenuated such injury. CONCLUSIONS:These findings demonstrate a pathogenic role of platelet microparticles in glomerular endothelium dysfunction, and suggest a potential therapeutic target, CXCL7, for treatment of early diabetic nephropathy.

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A modest decrease in endothelial NOS in mice comparable to that associated with human NOS3 variants exacerbates diabetic nephropathy.

Publications

A modest decrease in endothelial NOS in mice comparable to that associated with human NOS3 variants exacerbates diabetic nephropathy.

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