Proteinuric IgA Nephropathy Research Articles

Nephrology: what's new in 2023

Molecules such as sparsentan and budesonide look promising to treat proteinuric IGA nephropathy. SLGT2 inhibitors have a prominent place in nephroprotection and could be used in the treatment of acute kidney injury due to heart failure as well. High volume hemodiafiltration compared to hemodialysis improves survival in dialysis patients. Lessening dialysate temperature does not improve hemodynamic stability during the dialysis session. Sodium bicarbonate does not seem to protect renal function in renal transplant patients. SGLT2 inhibitors may have a beneficial effect in these patients in terms of nephroprotection.

Podocyte sphingomyelin phosphodiesterase acid-like 3b decreases among children with idiopathic nephrotic syndrome.

Sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b), a regulator of the cytoskeleton, is expressed on podocytes. Recent reports present evidence that it is directly targeted by rituximab in the treatment of intractable nephrotic syndrome. However, the implications of SMPDL-3b for treatment of paediatric-onset idiopathic nephrotic syndrome (INS) remain unclear. This study aimed to investigate the level of expression of SMPDL-3b in urine, serum, and biopsy specimens and explore its implications in treatment of patients with INS. Levels of urinary SMPDL-3b among 31 patients (20 in remission and 11 in relapse) with INS were analysed by dot blotting. For reference of precise quantitative analysis, we examined urinary excretion of SMPDL-3b from 10 patients with INS by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in both remitted and relapsed status. The levels of serum SMPDL-3b among 20 patients (13 in remission and 7 in relapse or onset) with INS were also measured using enzyme-linked immunosorbent assay. Further, the immunoreactivity of SMPDL-3b in the biopsy specimens obtained from patients with INS was compared with those from patients with proteinuric IgA nephropathy, lupus nephritis, and non-proteinuric controls. Urinary excretion of SMPDL-3b in patients with INS was significantly decreased in relapse cases compared with cases of remission and other types of proteinuric glomerular disease or controls by both dot blotting and LC-MS/MS method. On the other hand, serum SMPDL-3b level in INS was not different between cases of remission and relapse. Glomerular immunoreactivity of SMPDL-3b in patient with INS in remission was almost the same level to that of control. The expression of SMPDL-3b on podocytes is specifically decreased in paediatric-onset INS and its urinary excretion level reflects such conditions.

In patients with proteinuric IgA nephropathy, benefits of methylprednisolone were offset by harms.

Source Citation Lv J, Zhang H, Wong MG, et al; TESTING Study Group. Effect of oral methylprednisolone on clinical outcomes in patients with IgA nephropathy: The TESTING randomized clinical trial. J...

Role of immunosuppressive therapy and predictors of therapeutic effectiveness and renal outcome in IgA nephropathy with proteinuria.

IntroductionThe aim of the study was to analyze the role of immunosuppressive therapy and identify independent predictors of therapeutic effectiveness and outcome in IgA nephropathy (IgAN) patients with proteinuria.Material and methodsTwo hundred and six IgAN patients with proteinuria (1–3.5 g/day) were included between January 2005 and December 2011, and divided into two groups: group A (n = 125), receiving renin-angiotensin system blockade therapy alone; and group B (n = 81), combining the above with immunosuppressive therapy. The clinicopathological features, response and safety were recorded. In univariate and multivariate models, the factors that influence response to therapy and renal outcome, especially pathologic features, were analyzed.ResultsThe patients in group B presented more severe proteinuria and hypoalbuminemia with more severe hematuria (p < 0.05) but no significant difference in the pathologic changes compared with group A. After follow-up, the response rate was higher in group B than in group A (p < 0.001). No pathologic feature or clinical parameter apart from steroid therapy (HR = 0.500, 95% CI: 0.304–0.821, p = 0.006) was strongly associated with therapeutic effectiveness. Endocapillary hypercellularity (HR = 2.849, 95% CI: 1.244–6.524, p = 0.013) seemed to be an independent predictor of poor response to steroid therapy. The renal survival rate was not significantly different between the two groups (p = 0.074). Estimated glomerular filtration rate at baseline may be an independent predictor of renal outcome.ConclusionsSteroid therapy could be an effective therapy in proteinuric IgAN patients, and endocapillary hypercellularity seemed to predict poor response to steroid. Renal function at baseline rather than treatment strategies and pathologic features may be independently associated with renal survival.

Tubular NF-&#954;B is overexpressed in proteinuric patients with IgA nephropathy.

Increasing evidence suggests that nuclear factor κB (NF-κB) plays a pivotal role in many glomerulopathies. Therefore, the aim of the present study was to determine the tubular immunoexpression of NF-κB in non-proteinuric (n = 22) and proteinuric patients (n = 16) with IgA nephropathy (IgAN). Another purpose of this study was to examine the possible relationship between NF-κB immunoexpression and proteinuria, interstitial fibrosis as well as interstitial infiltrates. Tubular immunoexpression of NF-κB, interstitial monocytes/macrophages, T lymphocytes, B lymphocytes and interstitial area were determined using a computer image analysis system. The mean values of the tubular immunoexpression of NF-κB, interstitial area and interstitial monocytes/macrophages were in proteinuric IgAN patients significantly increased compared to non-proteinuric IgAN cases, whereas interstitial T and B lymphocytes did not differ between these groups. In proteinuric patients, tubular immunoexpression of NF-κB was highly significantly positively correlated with the degree of proteinuria. Moreover, in both the non-proteinuric and the proteinuric groups with IgAN, tubular immunoexpression of NF-κB was positively correlated with the interstitial area and interstitial monocytes/macrophages. Our findings raise the possibility that proteinuria causes tubular overexpression of NF-κB and, in the process, recruitment of monocytes/macrophages and tubulointerstitial injury in IgAN patients.

Tubular NF-κB is overexpressed in proteinuric patients with IgA nephropathy

Increasing evidence suggests that nuclear factor κB (NF-κB) plays a pivotal role in many glomerulopathies. Therefore, the aim of the present study was to determine the tubular immunoexpression of NF-κB in non-proteinuric (n = 22) and proteinuric patients (n = 16) with IgA nephropathy (IgAN). Another purpose of this study was to examine the possible relationship between NF-κB immunoexpression and proteinuria, interstitial fibrosis as well as interstitial infiltrates. Tubular immunoexpression of NF-κB, interstitial monocytes/macrophages, T lymphocytes, B lymphocytes and interstitial area were determined using a computer image analysis system. The mean values of the tubular immunoexpression of NF-κB, interstitial area and interstitial monocytes/macrophages were in proteinuric IgAN patients significantly increased compared to non-proteinuric IgAN cases, whereas interstitial T and B lymphocytes did not differ between these groups. In proteinuric patients, tubular immunoexpression of NF-κB was highly significantly positively correlated with the degree of proteinuria. Moreover, in both the non-proteinuric and the proteinuric groups with IgAN, tubular immunoexpression of NF-κB was positively correlated with the interstitial area and interstitial monocytes/macrophages. Our findings raise the possibility that proteinuria causes tubular overexpression of NF-κB and, in the process, recruitment of monocytes/macrophages and tubulointerstitial injury in IgAN patients.

Endothelin-1 and Endothelin A Receptor Immunoreactivity Is Increased in Patients with Diabetic Nephropathy

Background: Endothelin-1 (ET-1) is associated with progression of renal disease, acting as a vasoconstrictor and growth factor for mesangial cells. ET-1 and endothelin A receptor (ET-RA) might have a role in the development of diabetic nephropathy (DN). The aims of this study were to determine ET-1 and ET-RA expressions in patients with DN and to correlate these expressions with renal function and proteinuria. Materials and methods: This is a cross-sectional study comprising 13 patients with type 2 diabetes mellitus and DN, 10 patients with proteinuric IgA nephropathy, and 13 samples of normal kidney from tumor nephrectomies. Demographic and selected data were collected from medical charts. The distribution and intensity of ET-1 and ET-RA immunostaining in renal biopsies were determined by immunohistochemistry and these correlated with the estimated glomerular filtration rate (eGFR) and proteinuria. Results: Patients with DN and IgA nephropathy on biopsy had markedly increased staining for ET-1 in endothelial cells of glomerular and peritubular capillaries when compared with controls (p < 0.001). ET-RA staining was also more intense and more diffuse in DN and IgA nephropathy than in controls (p = 0.019) and was restricted to tubular epithelial cells. A positive correlation was observed between ET-1 expression and proteinuria (r = 0.634, p = 0.027), but both ET-1 and ET-RA expressions did not correlate with eGFR. Conclusion: In this preliminary report, the higher expressions of ET-1 and ET-RA found in both DN and IgA nephropathy suggest a potential role for the endothelin system in DN as well as in other nondiabetic glomerular diseases.

Melanoma Differentiation-Associated Gene 5 Regulates the Expression of a Chemokine CXCL10 in Human Mesangial Cells: Implications for Chronic Inflammatory Renal Diseases

Mesangial cells play an important role in inflammatory reactions in kidney. Although viral infections often trigger the worsening of chronic inflammatory renal diseases, the mechanisms are largely unknown. Melanoma differentiation-associated gene 5 (MDA5) is a member of RNA helicase family with a conserved Asp-Glu-x-His (DExH) box. In the present study, we examined the effect of polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA (dsRNA) that mimics viral dsRNAs, on MDA5 expression using primary culture of human mesangial cells. The cells were simply treated or transfected with poly IC; the former procedure is a model of cells exposed to viral dsRNA released from dying cells, and the latter is a model of entry of RNA virus into the cytoplasm. Expression levels of MDA5 mRNA in mesangial cells were increased about 70-100 fold in response to either treatment or transfection with poly IC. MDA5 protein expression was significantly induced as well. RNA interference experiments revealed that poly IC treatment induced MDA5 expression via Toll-like receptor 3 (TLR3) and interferon (IFN)-β, and that poly IC trasnfection induced MDA5 expression via another DExH box RNA helicase, retinoic acid-inducible gene-I (RIG-I), and IFN-β. Moreover, MDA5 induced by poly IC, in turn, increased the expression of a chemokine CXCL10. In addition, immunohistochemical staining demonstrated a high level of MDA5 expression in glomeruli, mainly in mesangial cells, of patients with severe lupus nephritis or proteinuric IgA nephropathy. MDA5 may be involved not only in physiological antiviral reactions but also in chronic inflammation in glomerular mesangial cells.

IgA-Nephropathie - Neues zur Pathogenese und Therapie

Recent findings have improved our understanding of IgA nephropathy (IgAN) pathogenesis: Poorly galactosylated IgA 1 is increased in serum and mesangial deposits. Additionally, IgG-autoantibodies against poorly galactosylated IgA 1 are detectable in serum. Genetic studies revealed an association between certain HLA-polymorphisms and the occurence of IgAN. The optimal therapy of IgAN remains uncertain. The value of a low normal blood pressure control in proteinuric IgAN patients is not controversial. The best evidence for immunosuppressants exists for corticosteroids in proteinuric IgAN patients with normal or mildly reduced renal function. No additional benefit but more side effects are observed in a combination therapy of steroids and azathioprine in such patients. The potential benefit of an immunosuppressive therapy in addition to an already optimized supportive therapy is currently under investigation in the ongoing German STOP IgAN Study.

The origin and the clinical significance of urinary angiotensinogen in proteinuric IgA nephropathy patients

Background. Urinary angiotensinogen (AGT) was reported as a marker of renal injury in chronic kidney disease patients. However, the main source of urinary AGT is unknown in proteinuric patients because the disrupted filtration barrier might cause AGT filtration. We investigated the origin and the clinical importance of urinary AGT in proteinuric IgA nephropathy (IgAN) patients.Methods. In patients with biopsy-proven IgAN, urinary and plasma AGT was measured using a sandwich ELISA and compared with intrarenal AGT expression. The patients were followed up for 3 years.Results. Natural logarithm of the urinary AGT/creatinine (ln (urinary AGT/Cr)) was positively correlated with intrarenal expression of AGT (ln (urinary AGT/Cr) versus AGT/β-actin, r = 0.620, P < 0.0001; ln (urinary AGT/Cr) versus AGT density, r = 0.452, P = 0.007). Ln (urinary AGT/Cr) showed a positive correlation with urinary protein/creatinine ratio (PCR) but a negative correlation with estimated glomerular filtration rate (eGFR). Regression analyses showed that ln (urinary AGT/Cr) was a significant determinant of urinary PCR and eGFR 3 years after biopsy.Conclusions. Urinary AGT reflects intrarenal AGT expression and correlates with the extent of proteinuria and renal function. Our study indicates the intrarenal compartment as the main source of urinary AGT, suggesting its clinical implication as an important biomarker in proteinuric IgAN patients.

Randomized controlled clinical trial of corticosteroids plus ACE-inhibitors with long-term follow-up in proteinuric IgA nephropathy

Randomized controlled clinical trial of corticosteroids plus ACE-inhibitors with long-term follow-up in proteinuric IgA nephropathy

Predictors for progression in immunoglobulin A nephropathy with significant proteinuria

Proteinuria is a primary factor requiring treatment in immunoglobulin (Ig)A nephropathy. The purpose of this study was to assess the relevance of treatment response and relapse of proteinuria with renal function decline. One hundred and twenty-five biopsy-proven primary IgA nephropathy patients who had more than 1.0 g/day proteinuria at the first assessment were studied. All patients underwent anti-proteinuric treatment, and the association of the rate of renal function decline with treatment responsiveness, clinical and laboratory data was investigated. The treatment response of the patients was: 30.4% complete response (<0.3 g/day proteinuria), 32.8% partial response (0.3-1.0 g/day), 23.2% minimal response (decrement but not reduced to <1 g/day) and 13.6% no response (no decrement of proteinuria). The slope of renal function decline (-1.06 vs-1.24 mL/min per 1.73 m(2)/year, P = 0.580) was comparable between complete and partial response groups, but they were slower than those of minimal or non-response groups (P < 0.001). In multivariate analysis including other parameters, mean arterial pressure (MAP; beta = -0.240, P = 0.004) during follow up, minimal (beta = -0.393, P < 0.001) and non-response (beta = -0.403, P < 0.001) were significant predictors. In further investigation of complete and partial response groups, MAP (beta = -0.332, P = 0.001) and relapse of proteinuria (beta = -0.329, P = 0.001) were independently associated with slope of renal decline. Achievement of less than 1.0 g/day proteinuria and MAP were important for limiting the loss of renal function, and relapse of proteinuria should be closely monitored in proteinuric IgA nephropathy.

Beneficial effect of pioglitazone in proteinuric IgA nephropathy with concomitant ACEI/ARB treatment.

Methods: Forty-one biopsy-proven IgAN patients with proteinuria (>0.5g/day) who were currently treated with renin angiotensin system inhibitors and had at least two out of four risk factors for progressive disease (male gender, blood pressure >150/90 mmHg, creatinine clearance of 20-80 mL/min/1.73m 2 , and chronicity index >1) were randomly assigned to receive either PGZ 30 mg/day (PGZ group; n=21) or placebo (control group, n=20) for 16 weeks. Results: Baseline characteristics of patients in both groups were comparable. Following 16-week treatment, proteinuria in the PGZ group was significantly lower than the control group, [1.2 vs. 2.1 g/day (p<0.05)]. Patients in the PGZ group also showed a significant reduction in urinary excretion of TGF-β (from 361.4 to 234.4 ng/gCr) and VEGF (from 1353.1 to 765.1 ng/gCr) after 16-week treatment (p<0.05, both). Conclusion: PGZ significantly reduced proteinuria, urinary TGF-β, and urinary VEGF in IgAN patients. These findings suggest that PGZ could have a role in the treatment of proteinuric IgAN. Further studies with larger cases and longer follow-up time are warranted.

Randomized controlled clinical trial of corticosteroids plus ACE-inhibitors with long-term follow-up in proteinuric IgA nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common cause of chronic renal failure among primary glomerulonephritis patients. The best treatment for IgAN remains poorly defined. We planned a long-term, prospective, open-label, multicentre, centrally randomized controlled trial to assess whether the combination of prednisone and ramipril was more effective than ramipril alone in patients with proteinuric IgAN. Ninety-seven biopsy-proven IgAN patients with moderate histologic lesions, 24-h proteinuria > or =1.0 g and estimated glomerular filtration rate (eGFR) > or = 50 ml/min/ 1.73 m(2) were randomly allocated to receive a 6-month course of oral prednisone plus ramipril (combination therapy group) or ramipril alone (monotherapy group) for the total duration of follow-up. The primary outcome was the progression of renal disease defined as the combination of doubling of baseline serum creatinine or end-stage kidney disease (ESKD). The secondary outcomes were the rate of renal function decline defined as the eGFR slope over time, and the reduction of 24-h proteinuria. After a follow-up of up to 96 months, 13/49 (26.5%) patients in the monotherapy group reached the primary outcome compared with 2/48 (4.2%) in the combination therapy group. The Kaplan-Meier analysis showed a significantly higher probability of not reaching the combined outcome in the combination therapy group than in the monotherapy group (85.2% versus 52.1%; log-rank test P = 0.003). In the multivariate analysis, baseline serum creatinine and 24-h proteinuria were independent predictors of the risk of primary outcome; treatment with prednisone plus ramipril significantly reduced the risk of renal disease progression (hazard ratio 0.13; 95% confidence interval 0.03-0.61; P = 0.01). The mean rate of eGFR decline was higher in the monotherapy group than in the combination therapy group (-6.17 +/- 13.3 versus -0.56 +/- 7.62 ml/min/ 1.73 m(2)/year; P = 0.013). Moreover, the combined treatment reduced 24-h proteinuria more than ramipril alone during the first 2 years. Our results suggest that the combination of corticosteroids and ramipril may provide additional benefits compared with ramipril alone in preventing the progression of renal disease in proteinuric IgAN patients in the long-term follow-up.

Combined treatment with renin-angiotensin system blockers and polyunsaturated fatty acids in proteinuric IgA nephropathy: a randomized controlled trial

Currently, several therapeutic protocols exist for IgA nephropathy (IgAN); results in slowing the progression to end-stage renal disease (ESRD) are variable, but approximately 30-40% of patients require replacement therapy (dialysis or renal transplantation) by 20 years from the onset. The adverse effects brought by the chronic assumption of drugs can be a potential limit. Actually, the most used therapies for IgAN are renin-angiotensin system blockers (RASB), glucocorticoids and immunosuppressive agents. Trials with polyunsaturated fatty acids (PUFA) in IgAN have been done since the first successful attempt by Hamazaki in 1984, resulting in alternate answers, but no trials have ever been done testing the efficacy of combined therapy with RASB and PUFA. We tested the effect of a 6-month course of PUFA (3 grams/day) in a group of 30 patients with biopsy-proven IgAN and proteinuria already treated with RASB randomized to receive PUFA supplementation or to continue their standard therapy. The primary end-point was the percent reduction of proteinuria from the baseline. Secondary end-points were modifications in glomerular filtration rate (GFR), blood pressure, serum triglycerides and erythrocyturia. At the end of the 6-month trial, the percent reduction of proteinuria was 72.9% in the PUFA group and 11.3% in the RASB group (P < 0.001). A reduction of >or=50% of baseline proteinuria was achieved in 80.0% of PUFA patients and 20.0% of RASB patients (P = 0.002). Erythrocyturia was significantly lower in the PUFA group (P = 0.031). No significant changes in renal function, blood pressure and triglycerides were observed. PUFA associated with RASB reduced proteinuria in patients with IgAN more than RASB alone.

Dual Therapy with ACE Inhibitors and Angiotensin II Receptor Blockers in Proteinuric IgA Nephropathy Patients

Experimental evidence supports dual pharmacologic blockade of the renin–angiotensin system with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in proteinuric renal disease. Nonetheless, exaggerated therapeutic benefits are frequently the rule rather than the exception in the experimental or trial setting. The difference between the clinical trial setting (efficacy) and actual practice (effectiveness) should be borne in mind before the recommendation of any new therapy as the standard of care. With this in mind, we examined the effectiveness and safety of dual therapy on a cohort of adults with proteinuric IgA nephropathy in a usual clinical setting. The primary end point was reduction in proteinuria, which has been shown to be a significant risk factor for end-stage renal disease. [Hong Kong J Nephrol 2007;9(2):89–93]

Efficacy of long-term alternate day prednisolone therapy in childhood IgA nephropathy

Background Recent reports suggest that long-term oral prednisolone with or without cytotoxic agents may decrease proteinuria and histologic alterations, and preserve renal function in patients with proteinuric IgA nephropathy.

The renal hemodynamic response to an oral protein load is normal in IgA nephropathy.

The study was devised to explore the effects of an acute oral protein load on renal hemodynamic response in patients with IgA nephropathy (IgAN). The study was performed in 10 proteinuric IgAN patients (800 +/- 300 mg/day) and in 20 healthy controls (matched by sex, age, BMI, BSA, plasma creatinine, plasma urea, urinary urea and protein intake). Blood pressure and creatinine clearance were nearly identical in the two groups. GFR and RPF, measured as the clearance of inulin and of p-aminohippurate (PAH) were studied before and after a meat meal which provided 2 g of protein/kg BW. Following the protein load, renal reserve, percent renal reserve and postmeal cumulative changes of GFR were not significantly different in IgAN and controls. Filtration fraction (FF) at baseline was significantly higher (p < 0.01) in IgAN than in controls (25.5 +/- 1.41 vs. 19 +/- 2%). Postmeal hyperemia and hyperfiltration did not affect FF in either group. Filtration capacity in IgAN was lower (p<0.02) than in controls (117 +/- 5.6 vs. 137.9 +/- 7.0 ml/min x 1.73 m2), whereas the percent of filtration capacity utilized at rest was identical in controls and in IgAN. Creatinine clearance overestimated GFR in IgAN. The data indicate that renal hemodynamic response to proteins in IgAN is normal.