Immunoglobulin A Nephropathy: A Review of Current Literature on Emerging Pathophysiology

The Spectrum of Glomerulopathies in Kashmir: A Tertiary Care Experience

BACKGROUND

There is a paucity of data on the spectrum of renal diseases prevalent in the Jammu and Kashmir region.

OBJECTIVES

To determine the spectrum of glomerulopathies in adult patients attending a tertiary care centre.

METHODS

Two hundred and twenty-one adequate biopsies from native kidneys of adult patients who presented with features suggestive of glomerular diseases at Sheri Kashmir Institute of medical sciences Srinagar Kashmir for the last 8 years were studied in a retrospective manner. Light and immunofluorescence (IF) microscopy were performed to evaluate these biopsies after obtaining well-informed consent from each patient.

RESULTS

Of the 221 biopsies carried out, 150 were performed on males and 71 on females with the mean age of 29 ± 13.5 years. The main presentation was the nephrotic syndrome in 177 (80%), hypertension in 60 (27%), renal insufficiency in 48 (21.7%), and abnormal urinary sediment in 42 (20.3%) of patients. The histopathology revealed minimal change disease (MCD) in 69 (31.2%), membranous glomerulonephritis (MGN) in 48 (21.7%), focal segmental glomerulsclerosis (FSG) in 49 (18%), and mesangioproliferative glomerulonephritis in 16 (7.2%). Patients with atypical presentation of diabetes mellitus showed diabetic nephropathy in 12 (5.4%) patients. Lupus nephritis was in 5 (2.2%) patients. Majority of the patients with MPGN had Immunoglobulin A deposits on IF. While evaluating the underlying cause of MGN, only 1 patient, a 62-year-old male, proved to have adenocarcinoma of the stomach. In the remaining patients, no secondary cause could be found. Thrombotic complications seen in our study were deep venous thrombosis, renal vein thrombosis and middle cerebral artery thrombosis.

CONCLUSION

MCD and MGN were the most common primary glomerular diseases observed in our centre.

Anti-inflammatory effects of triptolide on IgA nephropathy in rats

IgA nephropathy (IgAN) is the finding of immune deposits predominantly containing polymeric IgA in the glomerular mesangium on renal biopsy. Recently studies show that inflammation may involve in the progression of renal glomerulosclerosis and tubulointerstitial scarring in IgAN. This study was designed to evaluate the renoprotective effect of triptolide on IgAN rat model. IgAN was induced in Sprague-Dawley rats by oral and intravenous immunization with BSA for 12 weeks. Rats were treated with triptolide (200 μg/kg/d intragastrically) from 12 to 28 weeks. At Week 28, the rats was sacrificed, kidneys and blood samples were collected for further analysis. Our data shown that IgAN rat model showed marked deterioration of proteinuria together with higher levels of the urine protein:creatinine ratio compared to the normal control. Animals that underwent intermittent exposure to triptolide treatment exhibited significant improvements in the functional parameters without severe side effects. Rats developing IgAN had profound mesangial proliferation and mesangial expansion, intense and diffuse glomerular IgA deposition, while triptolide treatment significantly attenuated it. We also observed that treatment with triptolide significantly decreases serum levels of IL-1β and IL-18, and may exerted anti-inflammatory effects by down-regulating NLRP3 and TLR4 expression. Our study clearly demonstrated that triptolide prevents IgAN progression via an amelioration of inflammasome-mediated proinflammatory cytokine production, thus brought a light of hope for treatment of IgAN.

Profiling and initial validation of urinary microRNAs as biomarkers in IgA nephropathy

Background. MicroRNAs (miRNAs) have been found in virtually all body fluids and used successfully as biomarkers for various diseases. Evidence indicates that miRNAs have important roles in IgA nephropathy (IgAN), a major cause of renal failure. In this study, we looked for differentially expressed miRNAs in IgAN and further evaluated the correlations between candidate miRNAs and the severity of IgAN. Methods. Microarray and RT-qRCR (real-time quantitative polymerase chain reaction) were sequentially used to screen and further verify miRNA expression profiles in urinary sediments of IgAN patients in two independent cohorts. The screening cohort consisted of 32 urine samples from 18 patients with IgAN, 4 patients with MN (membranous nephropathy), 4 patients with MCD (minimal changes disease) and 6 healthy subjects; the validation cohort consisted of 102 IgAN patients, 41 MN patients, 27 MCD patients and 34 healthy subjects. The renal pathological lesions of patients with IgAN were evaluated according to Lee's grading system and Oxford classification. Results. At the screening phase, significance analysis of microarrays analysis showed that no miRNA was differentially expressed in the IgAN group compared to all control groups. But IgAN grade I-II and III subgroups (according to Lee's grading system) shared dysregulation of two miRNAs (miR-3613-3p and miR-4668-5p). At the validation phase, RT-qPCR results showed that urinary level of miR-3613-3p was significantly lower in IgAN than that in MN, MCD and healthy controls (0.47, 0.44 and 0.24 folds, respectively, all P < 0.01 by Mann-Whitney U test); urinary level of miR-4668-5p was also significantly lower in IgAN than that in healthy controls (0.49 fold, P < 0.01). Significant correlations were found between urinary levels of miR-3613-3p with 24-hour urinary protein excretion (Spearman r = 0.50, P = 0.034), eGFR (estimated glomerular filtration rate) (r = - 0.48, P = 0.043) and Lee's grades (r = 0.57, P = 0.014). Similarly, miR-4668-5p was significantly correlated with eGFR (r = - 0.50, P = 0.034) and Lee's grades (r = 0.57, P = 0.013). For segmental glomerulosclerosis according to Oxford classification, patients scored as S0 had significantly lower levels of urinary miR-3613-3p and miR-4668-5p than those scored as S1 (0.41 and 0.43 folds, respectively, all P < 0.05). Conclusions. The expression profile of miRNAs was significantly altered in urinary sediments from patients with IgAN. Urinary expression of miR-3613-3p was down-regulated in patients with IgAN. Moreover, urinary levels of both miR-3613-3p and miR-4668-5p were correlated with disease severity. Further studies are needed to explore the roles of miR-3613-3p and miR-4668-5p in the pathogenesis and progression of IgA nephropathy.