Oxidative stress in primary glomerular diseases: a comparative study

Severe hyperbilirubinemia is associated with higher risk of contrast-related acute kidney injury following contrast-enhanced computed tomography

INTRODUCTION

Contrast-induced acute kidney injury (CI-AKI) is associated with high risks of morbidity and mortality. Hyperbilirubinemia might have some renal protection but with no clear cutoff value for protection. Related studies are typically on limited numbers of patients and only in conditions of vascular intervention.

METHODS

We performed this study to elucidate CI-AKI in patients after contrast-enhanced computed tomography (CCT). The outcomes were CI-AKI, dialysis and mortality. Patients were divided to three groups based on their serum levels of total bilirubin: ≤1.2 mg/dl, 1.3-2.0 mg/dl, and >2.0 mg/dl.

RESULTS

We enrolled a total of 9,496 patients who had received CCT. Patients with serum total bilirubin >2.0 mg/dl were associated with CI-AKI. Those undergoing dialysis had the highest incidence of PC-AKI (p<0.001). No difference was found between the two groups of total bilirubin ≤1.2 and 1.3-2.0 mg/dl. Patients with total bilirubin >2mg/dl were associated with CI-AKI (OR = 1.89, 1.53-2.33 of 95% CI), dialysis (OR = 1.40, 1.01-1.95 of 95% CI) and mortality (OR = 1.63, 1.38-1.93 of 95% CI) after adjusting for laboratory data and all comorbidities (i.e., cerebrovascular disease, coronary artery disease, peripheral arterial disease, and acute myocardial infarction, diabetes mellitus, hypertension, gastrointestinal bleeding, cirrhosis, peritonitis, ascites, hepatoma, shock lung and colon cancer). We concluded that total bilirubin level >2 mg/dl is an independent risk factor for CI-AKI, dialysis and mortality after CCT. These patients also had high risks for cirrhosis or hepatoma.

CONCLUSION

This is the first study providing evidence that hyperbilirubinemia (total bilirubin >2.0 mg/dl) being an independent risk factor for CI-AKI, dialysis and mortality after receiving CCT. Most patients with total bilirubin >2.0mg/dl had cirrhosis or hepatoma.

Blood concentration of aminothiols in children with relapse of nephrotic syndrome

BACKGROUND

The role of idiopathic nephrotic syndrome (INS) in the pathogenesis of atherosclerosis in childhood has not been clearly elucidated. However, antioxidative defense in INS is thought to be imbalanced. This study aimed to assess the changes of plasma concentration of selected aminothiols in the blood of children with INS at various stages of the disease.

METHODS

This cross-sectional study was conducted in 125 children aged 2-18 years. The children were divided into 4 groups: group A, early relapse (n=37); group B, early remission for 4-6 weeks from the onset (n=37); group C, late steroid-free remission (n=31); and group D, long-term remission for 2-5 years (n=20). Control group (E) consisted of 30 age- and gender-matched healthy children. The study protocol comprised an analysis of plasma concentrations of glutathione, homocysteine, cysteine and cysteinylglycine by high-performance liquid chromatography. Fractions of protein-bound and free aminothiols were measured. Endothelial injury was assessed by thrombomodulin, PAI-1 concentration, and von Willebrand factor activity.

RESULTS

The children with INS had unbalanced aminothiol metabolism only in relapse and early remission, that shifted towards increased oxidative processes. Administration of cyclosporine A caused a significant increase in homocysteine and cysteine concentration. Changes in aminothiol metabolism were significantly related to endothelial injury.

CONCLUSIONS

The findings of this study may be helpful in elucidating the pathogenesis of premature atherosclerosis in patients with INS refractory to the treatment or in the case of frequent relapse.

Association of serum total bilirubin with renal outcome in Japanese patients with stages 3-5 chronic kidney disease

OBJECTIVE

Serum bilirubin has been reported to be associated with the progression of kidney disease in patients with diabetic nephropathy. Less is known, however, about the relationship between bilirubin and chronic kidney disease (CKD) of other etiologies. This study was designed to clarify whether serum total bilirubin concentration is associated with kidney disease progression in patients with CKD independent of etiology.

MATERIALS AND METHODS

This prospective observational study enrolled 279 consecutive patients with stages 3-5 CKD. The renal endpoint was the composite of the doubling of serum creatinine or end-stage renal disease requiring dialysis. Patients were divided into three groups by their serum total bilirubin concentrations: ≤0.3 (lowest), 0.4-0.5 (middle), and ≥0.6 (highest) mg/dL. A Cox proportional hazards model was applied to determine the risk factors for poor renal outcome.

RESULTS

The median follow-up period was 21months. One-hundred and three patients reached renal end points. After multivariable adjustment, a 0.1mg/dL increase in serum bilirubin was associated negatively with poor renal outcome (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.60-0.87). In addition, after adjustment for confounding factors, including traditional and nontraditional cardiovascular risk factors, the middle (HR 3.14, 95% CI 1.36-8.57) and lowest (HR 4.22, 95% CI 1.81-11.59) bilirubin groups had significantly higher HRs for renal outcome than the highest bilirubin group.

CONCLUSIONS

Lower serum bilirubin concentration was independently associated with adverse renal outcomes, suggesting that the measurement of serum bilirubin is useful for predicting kidney disease progression in patients with moderate to severe CKD.

Circulating bilirubin and defense against kidney disease and cardiovascular mortality: mechanisms contributing to protection in clinical investigations

Unconjugated bilirubin is an endogenous circulating antioxidant, bound to albumin, and therefore is retained in the vascular compartment. Bilirubin has well-documented neurotoxic effects in infants; however, current evidence indicates mildly elevated bilirubin is associated with protection from cardiovascular disease and all-cause mortality in adults. Recent clinical studies show mildly elevated bilirubin is associated with protection from kidney damage and dysfunction, in addition to cardiovascular events and all-cause mortality in patients undergoing hemodialysis. This is the first review to examine the clinical evidence and summarize the potential mechanisms of action that link bilirubin to protection from kidney damage, subsequent kidney failure, and dialysis-related mortality. With this understanding, it is hoped that new therapies will be developed to prevent renal dysfunction and mortality from cardiovascular disease in at-risk individuals.

Oxidative stress markers in exhaled breath condensate in lung fibroses are not significantly affected by systemic diseases

Exhaled breath condensate (EBC) is assumed to reflect processes in the lungs, yet it is unknown whether oxidative stress markers in EBC are affected by systemic disorders (atherosclerosis, hypertension, diabetes) or whether lung diseases increase markers in plasma and urine. 8-isoprostane, 4-hydroxy-trans-2-nonenale (HNE) and malondialdehyde (MDA) were measured using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) in EBC, plasma and urine in 82 patients (45 with asbestosis and hyalinosis, and 37 with silicosis) and in 29 control subjects. 8-isoprostane and HNE in EBC, and HNE in urine were higher in both groups of patients. In addition, 8-isoprostane in plasma and urine, and MDA in urine were higher in asbestos-exposed patients and MDA in plasma in silicotics, with this marker in plasma correlated with the grade of silicosis. In all subjects, 8-isoprostane in EBC correlated with urine (r=0.38, p<0.001) and plasma levels (r=0.28, p=0.003), and HNE and MDA with urine levels (r=0.31, p<0.001; r=0.23, p=0.016, respectively). Most markers positively correlated with lung function impairment, EBC markers negatively with vitamin E supplementation. To conclude: The influence of satisfactorily controlled systemic disorders on markers in EBC in patients with pneumoconioses is not significant. In addition to oxidative stress markers in EBC, lung fibroses may increase oxidative stress markers in plasma and urine.

Up regulation of the GRP-78 and GADD-153 and down regulation of Bcl-2 proteins in primary glomerular diseases: a possible involvement of the ER stress pathway in glomerulonephritis

The role of endoplasmic reticulum (ER) stress in kidney diseases is not well elucidated. Fifty patients with primary glomerular diseases (PGD): minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous glomerulonephritis (MGN), membranoproliferative glomerulonephritis (MPGN), and crescentic glomerulonephritis, n = 10 (each group) were enrolled. MCD, FSGS, and MGN patients were sub-grouped as nonproliferative glomerulonephritis (NPGN) and MPGN, RPGN as proliferative glomerulonephritis (PGN). Glucose regulated proteins (GRP-78), growth arrest and DNA damage inducible proteins (GADD-153), and Bcl-2 protein expression was analyzed by Western blotting, immunofluorescence and immunohistochemistry in the kidney biopsy. Up regulation of GADD-153, GRP-78, with more pronounced expression in PGN vs. NPGN (P < 0.05) and down regulation of Bcl-2 proteins was observed in the GN (PGD excluding MCD) as compared to MCD (P < 0.05). Our results suggest that renal injury in PGD is associated with ER stress and ER stress may be involved in the rapid progression of PGN to renal failure.