Kidney disease, genotype and the pathogenesis of vasculopathy

Characteristics and outcomes among pregnant women with end-stage renal disease on hemodialysis

PURPOSE

Pregnancy among women with end-stage renal disease (ESRD) has risen in frequency, which may be attributed to improvements in hemodialysis care. Our objective was to describe baseline characteristics and pregnancy outcomes among women with ESRD on hemodialysis.

METHODS

Using the United States' Healthcare Cost and Utilization Project-Nationwide Inpatient Sample, we created a cohort of women with ESRD on hemodialysis who gave birth between 2005 and 2015. We determined the proportion of adverse maternal and neonatal outcomes among this cohort. Then, we created a composite measure of vascular-mediated adverse pregnancy outcomes. Women who experienced at least one of either preeclampsia, intrauterine growth restriction, or intrauterine fetal death were categorized as having the composite measure. Then, multivariate regression models were used to estimate the associations between maternal baseline demographic and clinical characteristics and the composite measure.

RESULTS

Among 8,765,973 deliveries between 2005 and 2015, 307 were to women with ESRD on hemodialysis. Over the study period, the incidence of pregnancies to women with ESRD increased from 0.47 to 5.76/100,000 births. An estimated 28% of pregnancies were complicated by preeclampsia, 8% by placental abruption, 58% delivered by cesarean, and in the postpartum, 28% required blood transfusions and 6% experienced sepsis. About 45% of babies were born preterm and 14% had IUGR. The composite measure of adverse events was not found to be associated with any baseline maternal characteristics.

CONCLUSIONS

The frequency of pregnant women with ESRD on hemodialysis has risen, with adverse pregnancy complications for both mother and fetus. Transfer to high-risk centers is suggested for women with ESRD.

Pregnancy outcomes among renal transplant recipients and patients with end-stage renal disease on dialysis

AIM

The purpose of our study is to compare pregnancy outcomes between women with a functioning renal transplant and women with end-stage renal disease (ESRD).

METHODS

We carried out a population-based retrospective cohort study using the Healthcare Cost and Utilization Project Nationwide Inpatient Sample database from 2006 to 2011. Logistic regression analysis was used to estimate the age-adjusted effect of functioning renal transplant vs. ESRD requiring dialysis on pregnancy outcomes.

RESULTS

We identified 264 birth records to women with a functional renal transplant and 267 birth records to women with ESRD on dialysis among 5,245,452 births. As compared to women with ESRD on dialysis, renal transplant recipients were less likely to have placental abruption [odds ratio, OR 0.23 (95% confidence interval, CI 0.08-0.70)], to receive blood transfusions [OR 0.17 (95% CI 0.09-0.30)], and to have growth-restricted and small-for-gestational-age babies [OR 0.45 (95% CI 0.23-0.85)]. Renal transplant recipients were more likely to have an instrumental delivery [OR 15.38 (95% CI 1.92-123.3)]. Among renal transplant women, there was a trend towards delivery by cesarean section as compared to patients with ESRD [OR 1.31 (95% CI 0.93-1.85)]. However, these results were not statistically significant. Fetal deaths were less likely to occur in women with a renal transplant [OR 0.41 (95% CI 0.17-0.96)]. There were four maternal deaths among patients with ESRD on dialysis and no maternal deaths among renal transplant patients.

CONCLUSION

Patients with a functional renal graft had an overall lower rate of morbidity and adverse pregnancy complications when compared to patients with ESRD on dialysis.

Emerging roles for miRNAs in the development, diagnosis, and treatment of diabetic nephropathy

Although the causes of diabetic nephropathy are not yet fully known, emerging evidence suggests a role for epigenetic factors in the development of the disease. In particular, microRNAs (miRNAs) are becoming recognized as important mediators of biological processes relevant to diabetic nephropathy. Until recently, investigations of miRNAs in the development of diabetic nephropathy have remained relatively limited; however, the number of reports identifying potential new candidates and mechanisms of impact is presently expanding at a rapid pace. This review seeks to summarize these recent findings, focusing on new candidates and/or novel mechanisms, including the intersection between genetic variation and miRNA function in modulating disease expression, emerging in the field. We also review the latest advances in the diagnostic and therapeutic potential of miRNAs in the treatment of diabetic nephropathy.

Genome-wide SNP genotyping study using pooled DNA to identify candidate markers mediating susceptibility to end-stage renal disease attributed to Type 1 diabetes

AIMS

Genetic factors play a major role in the progression of kidney disease in diabetes. To identify candidate single nucleotide polymorphisms (SNPs) with potential effects on susceptibility to end-stage renal disease (ESRD), we performed a whole genome association scan using pooled DNA from Caucasian individuals with Type 1 diabetes.

METHODS

We utilized the Illumina Infinium II HumanHap 550 beadchip platform to genotype 555 352 SNPs in DNA pools comprised of 547 cases with ESRD and 549 control subjects with Type 1 diabetes duration > 20 years and no ESRD. Pooled probe intensity was used to predict mean allele frequency (MAF) for each locus. Individual genotyping was performed using the iPLEX assay in conjunction with the MassARRAY platform (Sequenom).

RESULTS

We identified 2870 markers showing substantial differences in MAF (5.0-10.7%) between pools. To initiate validation of these findings, we genotyped 22 high-ranking markers in 462 individuals with ESRD and 470 unaffected control subjects selected from the genome-wide SNP genotyping study sample. We observed the strongest evidence for association between ESRD and rs1749824, located in the ZMIZ1 gene [OR = 1.47 (1.21-1.78) per copy of T allele; P = 8.1 x 10(-5)] and rs9298190, located in the musculin gene [OR = 1.56 (1.28-1.91) per copy of C allele; P = 1.6 x 10(-5)]. Evidence for nominal association with markers in or near the IRS2, TMPO, BID, KLRA1, ELMO1 and CNDP1 genes was also observed (P < or = 0.0006).

CONCLUSIONS

These findings identify several novel loci which may contribute to ESRD susceptibility in individuals with Type 1 diabetes.

Characteristics and risk factors of intrarenal arterial lesions in patients with IgA nephropathy

BACKGROUND

Although the clinical importance of immunoglobulin-A nephropathy (IgAN) is widely recognized, the characteristics of intrarenal arterial lesions in this disease and the main factors associated with them have not been studied extensively, and a large-scale analysis of intrarenal arterial lesions in IgAN has not been performed.

METHODS

To clarify these issues, we investigated the prevalence, underlying factors and significance of intrarenal arterial lesions in 1005 patients with IgAN. We distinguished different degrees of severity of small artery and arteriolar lesions (mild, moderate and severe), using a semi-quantitative scoring system. We compared the arterial lesions of IgAN patients with those of 627 non-IgAN patients, who had mesangial proliferating glomerulonephritis without IgA deposits, and of 221 patients with membranous nephropathy (MN).

RESULTS

The IgAN patients with arterial lesions were significantly younger than the non-IgAN and MN patients (mean ages 34.6 vs 40.4 and 47.7 years, respectively). The prevalence of intrarenal small artery and arteriolar lesions was 54.6% in IgAN patients, compared with 26.6 and 47.1% in non-IgAN and MN patients, respectively; the percentages of moderate/severe arterial lesions were 37.0 vs 21.6 and 23.1%, respectively; and the percentages of hyaline changes were 43.7 vs 16.8 and 21.2%, respectively. The differences in the prevalence of lesions between IgAN patients and the two other groups were statistically significant for all three parameters. Our search for possible relationships between arterial-arteriolar lesions and various indirect outcome markers disclosed significant associations with hypertension, higher serum creatinine and uric acid, high urinary protein excretion, glomerulosclerosis, tubular atrophy and interstitial fibrosis. Furthermore, these parameters were changed more markedly in IgAN patients with moderate/severe arterial lesions and hyaline changes than in IgAN patients who had mild arterial lesions and wall thickening alone.

CONCLUSIONS

The prevalence of small intrarenal arterial-arteriolar lesions was higher in IgAN patients than in non-IgAN and MN patients; moreover, the lesions in IgAN patients were associated with younger age, were more severe and exhibited a higher degree of hyaline changes. Finally, the severity of small arterial- arteriolar lesions was linked to several markers of adverse outcome.

African American hypertensive nephropathy maps to a new locus on chromosome 9q31-q32

Hypertensive nephropathy (HN) and focal segmental glomerulosclerosis (FSGS) are significant causes of end-stage renal disease (ESRD), but no genes or loci have been associated with this phenotype among African Americans, a group at high risk. We performed a genomewide linkage scan with approximately 400 microsatellite markers on 23 individuals of a large four-generation African American family with 18 affected individuals (7 with ESRD), in which the 13-year-old proband (also with ESRD) presented with hypertension and proteinuria (2-4 g/day) and underwent a kidney biopsy that revealed FSGS-like lesions with arteriolar thickening. A genomewide scan revealed LOD scores of >2.5 for markers on chromosomes 3 and 9, and fine mapping was performed on 5 additional members (total 28 members) that showed a maximum multipoint LOD score of 5.4 in the 9q31-q32 region, under an autosomal dominant model with 99% penetrance. This 8-cM (6-Mb) region is flanked by markers D9S172 and D9S105, and further candidate gene sequencing studies excluded the coding regions of three genes (ACTL7A, ACTL7B, and CTNNAL1). To our knowledge, this is the first report of a locus, denoted as "HNP1," for the HN/FSGS phenotype in a large African American family with dominantly inherited nephropathy characterized by ESRD, hypertension, and some features of FSGS.