Journal of the American Society of Nephrology : JASN
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J. Am. Soc. Nephrol. · Oct 2013
The RIP1-kinase inhibitor necrostatin-1 prevents osmotic nephrosis and contrast-induced AKI in mice.
The pathophysiology of contrast-induced AKI (CIAKI) is incompletely understood due to the lack of an appropriate in vivo model that demonstrates reduced kidney function before administration of radiocontrast media (RCM). Here, we examine the effects of CIAKI in vitro and introduce a murine ischemia/reperfusion injury (IRI)-based approach that allows induction of CIAKI by a single intravenous application of standard RCM after injury for in vivo studies. Whereas murine renal tubular cells and freshly isolated renal tubules rapidly absorbed RCM, plasma membrane integrity and cell viability remained preserved in vitro and ex vivo, indicating that RCM do not induce apoptosis or regulated necrosis of renal tubular cells. ⋯ Direct evaluation of renal morphology by intravital microscopy revealed dilation of renal tubules and peritubular capillaries within 20 minutes of RCM application in uninjured mice and similar, but less dramatic, responses after IRI pretreatment. Necrostatin-1 (Nec-1), a specific inhibitor of the receptor-interacting protein 1 (RIP1) kinase domain, prevented osmotic nephrosis and CIAKI, whereas an inactive Nec-1 derivate (Nec-1i) or the pan-caspase inhibitor zVAD did not. In addition, Nec-1 prevented RCM-induced dilation of peritubular capillaries, suggesting a novel role unrelated to cell death for the RIP1 kinase domain in the regulation of microvascular hemodynamics and pathophysiology of CIAKI.
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J. Am. Soc. Nephrol. · May 2013
Randomized Controlled TrialImpact of early parenteral nutrition on metabolism and kidney injury.
A poor nutritional state and a caloric deficit associate with increased morbidity and mortality, but a recent multicenter, randomized controlled trial found that early parenteral nutrition to supplement insufficient enteral nutrition increases morbidity in the intensive care unit, including prolonging the duration of renal replacement therapy, compared with withholding parenteral nutrition for 1 week. Whether early versus late parenteral nutrition impacts the incidence and recovery of AKI is unknown. Here, we report a prespecified analysis from this trial, the Early Parenteral Nutrition Completing Enteral Nutrition in Adult Critically Ill Patients (EPaNIC) study. ⋯ During the first 2 weeks, ureagenesis resulted in net waste of 63% of the extra nitrogen intake from early parenteral nutrition. In conclusion, early parenteral nutrition does not seem to impact AKI incidence, although it may delay recovery in patients with stage 2 AKI. Substantial catabolism of the extra amino acids, which leads to higher levels of plasma urea, might explain the prolonged duration of renal replacement therapy observed with early parenteral nutrition.
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LDL cholesterol (LDL-C) is an important marker of coronary risk in the general population, but its utility in people with CKD is unclear. We studied 836,060 adults from the Alberta Kidney Disease Network with at least one measurement of fasting LDL-C, estimated GFR (eGFR), and proteinuria between 2002 and 2009. All participants were free of stage 5 CKD at cohort entry. ⋯ Specifically, the adjusted HRs (95% confidence intervals) of myocardial infarction associated with LDL-C of ≥4.9 compared with 2.6-3.39 mmol/L in participants with eGFR=15-59.9, 60-89.9, and ≥90 ml/min per 1.73 m(2) were 2.06 (1.59, 2.67), 2.30 (2.00, 2.65), and 3.01 (2.46, 3.69). In conclusion, the association between higher LDL-C and risk of myocardial infarction is weaker for people with lower baseline eGFR, despite higher absolute risk of myocardial infarction. Increased LDL-C may be less useful as a marker of coronary risk among people with CKD than the general population.
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J. Am. Soc. Nephrol. · Apr 2013
Cystathionine γ-lyase protects against renal ischemia/reperfusion by modulating oxidative stress.
Hydrogen sulfide (H2S) is an endogenous gasotransmitter with physiologic functions similar to nitric oxide and carbon monoxide. Exogenous treatment with H2S can induce a reversible hypometabolic state, which can protect organs from ischemia/reperfusion injury, but whether cystathionine γ-lyase (CSE), which produces endogenous H2S, has similar protective effects is unknown. Here, human renal tissue revealed abundant expression of CSE, localized to glomeruli and the tubulointerstitium. ⋯ In addition, overexpression of CSE in vitro reduced the amount of reactive oxygen species produced during stress. Last, the level of renal CSE mRNA at the time of organ procurement positively associated with GFR 14 days after transplantation. In summary, these results suggest that CSE protects against renal ischemia/reperfusion injury, likely by modulating oxidative stress through the production of H2S.
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J. Am. Soc. Nephrol. · Mar 2013
Phospholipase A2 receptor (PLA2R1) sequence variants in idiopathic membranous nephropathy.
The M-type receptor for phospholipase A2 (PLA2R1) is the major target antigen in idiopathic membranous nephropathy (iMN). Our recent genome-wide association study showed that genetic variants in an HLA-DQA1 and phospholipase A2 receptor (PLA2R1) allele associate most significantly with biopsy-proven iMN, suggesting that rare genetic variants within the coding region of the PLA2R1 gene may contribute to antibody formation. Here, we sequenced PLA2R1 in a cohort of 95 white patients with biopsy-proven iMN and assessed all 30 exons of PLA2R1, including canonical (GT-AG) splice sites, by Sanger sequencing. ⋯ We identified 18 sequence variants, comprising 2 not previously described, 7 reported as rare variants (<1%) in the Single Nucleotide Polymorphism Database or the 1000 Genomes project, and 9 known to be common polymorphisms. Although we confirmed significant associations among 6 of the identified common variants and iMN, only 9 patients had the private or rare variants, and only 4 of these patients were among the 60 who were PLA2R positive. In conclusion, rare variants in the coding sequence of PLA2R1, including splice sites, are unlikely to explain the pathogenesis of iMN.