Circulating Permeability Factors in Focal Segmental Glomerulosclerosis: In V itro Detection

Introduction

The recurrence of proteinuria after kidney transplantation in patients with focal segmental glomerulosclerosis (FSGS) is considered proof of the presence of circulating permeability factors (CPFs). The aim of this study is to demonstrate the presence of plasma CPFs using series of in vitro assays.

Methods

Podocytes and endothelial cells (glomerular microvascular endothelial cells [GMVECs]) were incubated with plasma from FSGS patients with presumed CPFs in relapse and remission and from steroid-resistant nephrotic syndrome (SRNS), steroid-sensitive nephrotic syndrome (SSNS), membranous nephropathy (MN), and healthy controls (hCtrls). Cell viability, podocyte actin cytoskeleton architecture, and reactive oxygen species (ROS) formation with or without ROS scavenger were investigated by Cell Counting Kit-8 assay, immunofluorescence staining, and CM-H2DCFDA probing, respectively.

Results

Presumed CPF-containing plasma causes a series of events in podocytes but not in GMVECs. These events include actin cytoskeleton rearrangement and excessive formation of ROS, which results in podocyte loss. These effects were solely observed in response to CPF plasma collected during relapse, but not in response to plasma of hCtrls, or patients with SRNS, SSNS, and MN. The copresence of dimethylthiourea, a scavenger of ROS, abolished the aforementioned effects of CPF plasma.

Conclusion

We provide a panel of in vitro bioassays to measure podocyte injury and predict the presence of CPFs in plasma of patients with nephrotic syndrome (NS), providing a new framework for monitoring CPF activity that may contribute to future NS diagnostics or used for disease monitoring purposes. Moreover, our findings suggest that the inhibition of ROS formation or facilitating rapid ROS scavenging may exert beneficial effects in patients with CPFs.

Impaired thiol/disulphide homoeostasis in children with steroid-sensitive nephrotic syndrome

BACKGROUND

Abnormal thiol/disulphide homoeostasis (TDH) is responsible for the pathogenesis of various diseases. We aimed to examine the TDH in children with steroid-sensitive nephrotic syndrome (SSNS).

METHODS

A total of 131 children, 60 with SSNS and 71 healthy controls, participated in the study. Plasma total thiol (TT), native thiol (SH) and disulphide (SS) levels in the SSNS during remission and control groups were estimated using a new method developed by Erel and Neselioglu.

RESULTS

Albumin, TT, SH levels and SH/TT ratio were decreased, whereas SS/SH and SS/TT ratios were elevated in SSNS group compared with control group. However, there was no significant difference in SS levels between the two groups. Albumin level was positively correlated with TT, SH and SS levels in the SSNS group.

CONCLUSIONS

We found that TDH shifts in favour of oxidants in children with SSNS in remission. This shift indicates that SSNS patients are exposed to augmented oxidative stress.

Serum levels of malondialdehyde, vitamin C and E in idiopathic nephrotic syndrome: a meta-analysis

It is well documented that oxidative stress is involved in the pathogenesis of idiopathic nephrotic syndrome (INS). Malondialdehyde (MDA) is a measurement of lipid oxidation; vitamin C and E are important components of antioxidants. However, the association between MDA, vitamin C or E levels and INS remains elusive. A meta-analysis was performed to investigate the alteration of serum levels of MDA, vitamin C and E in INS compared with controls. Eight studies were included in our meta-analysis according to predefined criteria. Active INS patients demonstrated significantly higher level of serum MDA (SMD: 2.13, 95% CI: 1.511 to 2.749, p < 10(-4)), markedly lower levels of serum vitamin C (SMD: -1.449, 95% CI: -2.616 to -0.281, p = 0.015) and E (SMD: -1.45, 95% CI: -2.544 to -0.356, p = 0.009) compared with those in controls. Active steroid-sensitive nephrotic syndrome (SSNS) patients showed comparable levels of serum vitamin C and E to those in controls. INS subjects in the remission stage demonstrated significantly higher level of serum MDA (SMD: 1.028, 95% CI: 0.438 to 1.617, p < 10(-4)), markedly lower level of serum vitamin C (SMD: -2.235, 95% CI: -3.048 to -1.421, p < 10(4)) and similar level of serum vitamin E compared with those in controls. No significant publication bias was observed. In conclusion, the disorder of MDA and vitamin C persists in the remission stage of INS. It seems that the serum levels of vitamin C and E is associated with the responsiveness of INS to steroids. However, more studies should be performed in the future.

Protein thiols and butryrylcholinestrase in saliva of oral cancer patients

Oral squamous cell carcinoma is one of the most common malignancies recognized. Biomarkers which can predict presence of cancer and its progression can help in better management of these disorders. Over production of lipid peroxidation byproducts and disturbances in antioxidant defense system have been implicated in the pathogenesis of several diseases including oral cancer. Studies have shown a correlation of butyrylcholinesterase (BChE), with tumourigenesis, cell proliferation and cell differentiation. Earlier we have observed a significant elevation in plasma BChE and protein thiols in oral cancer patients which correlated well with stages of cancer. As it was not clear whether the above markers will be altered in saliva of oral cancer patients this study was undertaken. Institutional Ethics Committee gave permission to carry out this study. Total of 55 subjects comprising healthy controls (n = 30) and biopsy proven oral cancer patients (n = 25) consented to participate in this study. Salivary samples from cases were taken before any definitive treatment. Protein thiols and BChE were estimated in salivary samples using validated assay methods. Oral cancer patients had a significant increase in pre-treatment salivary BChE levels (p ≤ 0.001) and a significant decrease (p ≤ 0.001) in salivary thiols as compared to respective values in controls. Salivary protein thiols and BChE may have a role in pathophysiology of oral cancer. Saliva can be used as a potential non-invasive screening tool in oral cancer patients.

Serum albumin level accurately reflects antioxidant potentials in idiopathic nephrotic syndrome

BACKGROUND

Recent observation revealed that serum albumin plays an important role in the host defense mechanism as it is one of the important antioxidants. This study was conducted to investigate whether hypoalbuminemia contributes to a decreased biological antioxidant potentials (BAP) in idiopathic nephrotic syndrome (INS).

METHODS

Fifty three heparinised blood samples were obtained from 8 patients with INS (median 13.5 years). Eighteen samples from 6 patients with Henoch-Schönlein purpura (HSP median 7 years) were served as control. Intravenous human albumin preparation was also applied for comparison. Measurement of BAP in blood and human albumin preparation was determined by a newly developed devise called FRAS4(®). Comparison among groups and relationships between BAP and albumin concentrations or c-reactive protein (CRP) were studied by Kruskal-Wallis test and Spearman rank correlation test, respectively.

RESULTS

Serum levels of BAP was significantly lower in patients with nephrotic relapse than those in patients with nephrotic remission or HSP. BAP correlated well with serum albumin levels. Positive relationship was also found between concentration of albumin in human preparation and BAP. Weakly positive CRP sera disclosed both hypoalbuminemia and low BAP.

CONCLUSION

Our results suggest that decreased antioxidant potentials caused by hypoalbuminemia in INS may contribute to an aberrant immunity.

Oxidant stress in primary nephrotic syndrome: does it modulate the response to corticosteroids?

In order to assess the oxidative stress in newly diagnosed children with primary nephrotic syndrome (PNS), we serially measured serum total antioxidant capacity (TAC) and malondialdehyde (MDA) in 33 children with PNS and ten healthy matched controls. Patients were classified into two groups: those who had steroid-sensitive nephrotic syndrome (SSNS; n = 26) and those who had steroid-resistant nephrotic syndrome (SRNS; n = 7). Of the patients with SSNS, 15 were non-relapsers and 11 were relapsers. At the proteinuric phase, all patients had significantly higher MDA levels and lower TAC than the controls. These changes were more marked in patients with SRNS than in those with SSNS. During remission and still on corticosteroids, patients had higher TAC and similar MDA levels as in the proteinuric phase, but the TAC and MDA levels still significantly differed from those of the controls. More improvement in TAC and MDA levels occurred in patients following the weaning of corticosteroids, but TAC was still lower in the patients than in the controls. Moreover, TAC was higher in non-relapsers than in relapsers. Using a receiver operating characteristic curve, the initial response to corticosteroids could be predicted at serum TAC level > or =0.73 mM/L (sensitivity 89%, specificity 86%), while serum TAC levels < or = 1.14 mM/L after the weaning of corticosteroids could predict that the patient would not relapse (sensitivity 91%, specificity 80%). In conclusion, based on our results, PNS can be considered to be associated with oxidative stress even during remission. This stress may modulate the response to corticosteroids. Further prospective studies using larger numbers of patients are needed to validate these results.