The transient receptor potential channel C6 (TRPC6) is a slit diaphragm-associated protein in podocytes involved in regulating glomerular filter function. Gain-of-function mutations in TRPC6 cause hereditary focal segmental glomerulosclerosis (FSGS), and several human acquired proteinuric diseases show increased glomerular TRPC6 expression. Angiotensin II (AngII) is a key contributor to glomerular disease and may regulate TRPC6 expression in nonrenal cells. We demonstrate that AngII regulates TRPC6 mRNA and protein levels in cultured podocytes and that AngII infusion enhances glomerular TRPC6 expression in vivo. In animal models for human FSGS (doxorubicin nephropathy) and increased renin-angiotensin system activity (Ren2 transgenic rats), glomerular TRPC6 expression was increased in an AngII-dependent manner. TRPC6 expression correlated with glomerular damage markers and glomerulosclerosis. We show that the regulation of TRPC6 expression by AngII and doxorubicin requires TRPC6-mediated Ca(2+) influx and the activation of the Ca(2+)-dependent protein phosphatase calcineurin and its substrate nuclear factor of activated T cells (NFAT). Accordingly, calcineurin inhibition by cyclosporine decreased TRPC6 expression and reduced proteinuria in doxorubicin nephropathy, whereas podocyte-specific inducible expression of a constitutively active NFAT mutant increased TRPC6 expression and induced severe proteinuria. Our findings demonstrate that the deleterious effects of AngII on podocytes and its pathogenic role in glomerular disease involve enhanced TRPC6 expression via a calcineurin/NFAT positive feedback signaling pathway.
Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value < 1 × 10(-5)) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p < 1 × 10(-5)). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10(-10), odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression.
Background: Microalbuminuria is an early sign of kidney disease in diabetes and indicates cardiovascular risk. We tested if a prespecified urinary proteomic risk classifier (CKD273) was associated with development of microalbuminuria and if progression to microalbuminuria could be prevented with the mineralocorticoid receptor antagonist spironolactone. Methods: Prospective multicentre study in people with type 2 diabetes, normal urinary albumin excretion and preserved renal function in 15 European specialist centres. High-risk individuals determined by CKD273 were randomised 1:1 (interactive web response system) in a double-blind randomised controlled trial comparing spironolactone 25 mg o.d. to placebo. Primary endpoint was development of confirmed microalbuminuria in all individuals with available data. Secondary endpoints included reduction in incidence of microalbuminuria with spironolactone and association between CKD273 and impaired renal function defined as a glomerular filtration rate < 60 ml/min per 1•73 m 2. This study is registered with ClinicalTrials.gov: NCT02040441 and is completed. Findings: From March 25, 2014 to September 30, 2018 we followed 1775 participants, 12% (n=216) had high-risk urinary proteomic pattern of which 209 were included in the trial and assigned spironolactone (n=102) or placebo (n=107). Median follow-up time was 2•51 years (IQR 2•0-3•0). Progression to microalbuminuria was seen in 28•2% of high-risk and 8•9% of low-risk people (P< 0•001) (hazard ratio (HR), 2•48; 95% confidence interval [CI], 1•80 to 3•42 P<0•001, independent of baseline clinical characteristics). A 30% decline in eGFR from baseline was seen in 42 (19•4 %) high-risk participants compared to 62 (3•9 %) low-risk participants, HR 5•15; 95 % CI (3•41 to 7•76; p<0.0001). Development of microalbuminuria was seen in 35 (33%) randomised to placebo and 26 (25%) randomised to spironolactone treatment (HR 0•81, 95% CI, 0•49 to 1•34, P=0•41). Harms: hyperkalaemia was seen in 13 versus 4, and gynaecomastia in 3 versus 0 subjects on spironolactone and placebo, respectively. Interpretation: In people with type 2 diabetes and normoalbuminuria, the urinary proteomic classifier CKD273 was associated with a 2•5 times increased risk for progression to microalbuminuria over a median of 2•5 years, independent of clinical characteristics. Spironolactone did not prevent progression to microalbuminuria in high-risk subjects.
Higher HDL-C, as well as higher HDL-C-to-apoA-I and HDL-C-to-apoA-II ratios are strongly and independently related to a lower risk of future type 2 diabetes.
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