SPAK plays a pathogenic role in IgA nephropathy through the activation of NF-κB/MAPKs signaling pathway

Sterile 20/SPS1-related proline/alanine-rich kinase (SPAK) can stimulate production of proinflammatory cytokines and interact with inflammation-related molecules. However, it has yet to be determined whether SPAK plays a pathophysiological role in the complicated pathological mechanisms of IgA nephropathy (IgAN), which is mainly characterized by mesangial cell (MC) proliferation and is the most common form of glomerulonephritis. In the present study, we examined the pathophysiological role of SPAK in IgAN using a mouse model and cell models. Our results clearly showed that (1) SPAK deficiency prevents the development of IgAN and inhibits production of immune/inflammatory mediators and T cell activation and proliferation; and (2) when primed with IgA immune complexes (IgA IC), both peritoneal macrophages and primary MCs from SPAK knockout mice show markedly reduced production of proinflammatory cytokines and inhibition of NF-κB/MAPKs activation. We proposed that activation of SPAK and the NF-κB/MAPKs signaling pathway in MCs, macrophages and T cells of the glomerulus may be a mechanism underlying the pathogenesis of IgAN. The activation of SPAK in renal tubuloepithelial cells either directly by IgA IC or an indirect action of the activated MCs or infiltrating mononuclear leukocytes seen in the kidney may further aggravate the disease process of IgAN. Our results suggest that SPAK is a potential therapeutic target for the glomerular disorder.

Effect of tonsillectomy and its timing on renal outcomes in Caucasian IgA nephropathy patients

PURPOSE

The role of tonsillectomy in the treatment of IgA nephropathy in Caucasian patients is controversial.

METHODS

A retrospective cohort study was conducted in 264 patients with biopsy-proven primary IgA nephropathy to examine the association between tonsillectomy and long-term renal survival, defined as the incidence of estimated glomerular filtration rates (eGFRs) of ≤30 ml/min/1.73 m(2) or end-stage renal disease (the composite of initiation of dialysis treatment or renal transplantation). The association of tonsillectomy with renal end-points was examined using the Kaplan-Meier method and Cox models.

RESULTS

One-hundred and sixty-six patients did not undergo tonsillectomy (Group I, follow-up 130 ± 101 months) and 98 patients underwent tonsillectomy (Group II, follow-up 170 ± 124 months). The mean renal survival time was significantly longer for both end-points between those patients who underwent tonsillectomy (Group II) versus patients without tonsillectomy (Group I) (p < 0.001 and p = 0.005). The mean renal survival time was significantly longer for both end-points between those patients who had macrohaematuric episodes versus patients who had no macrohaematuric episodes (p = 0.035 and p = 0.019). Tonsillectomy, baseline eGFR and 24-h proteinuria were independent risk factors for both renal end-points.

CONCLUSION

Tonsillectomy may delay the progression of IgA nephropathy mainly in IgA nephropathy patients with macrohaematuria. Prospective investigation of the protective role of tonsillectomy in Caucasian patients is needed.

Osthole mitigates progressive IgA nephropathy by inhibiting reactive oxygen species generation and NF-κB/NLRP3 pathway

Renal reactive oxygen species (ROS) and mononuclear leukocyte infiltration are involved in the progressive stage (exacerbation) of IgA nephropathy (IgAN), which is characterized by glomerular proliferation and renal inflammation. The identification of the mechanism responsible for this critical stage of IgAN and the development of a therapeutic strategy remain a challenge. Osthole is a pure compound isolated from Cnidiummonnieri (L.) Cusson seeds, which are used as a traditional Chinese medicine, and is anti-inflammatory, anti-apoptotic, and anti-fibrotic both in vitro and in vivo. Recently, we showed that osthole acts as an anti-inflammatory agent by reducing nuclear factor-kappa B (NF-κB) activation in and ROS release by activated macrophages. In this study, we examined whether osthole could prevent the progression of IgAN using a progressive IgAN (Prg-IgAN) model in mice. Our results showed that osthole administration resulted in prevention of albuminuria, improved renal function, and blocking of renal progressive lesions, including glomerular proliferation, glomerular sclerosis, and periglomerular mononuclear leukocyte infiltration. These findings were associated with (1) reduced renal superoxide anion levels and increased Nrf2 nuclear translocation, (2) inhibited renal activation of NF-κB and the NLRP3 inflammasome, (3) decreased renal MCP-1 expression and mononuclear leukocyte infiltration, (4) inhibited ROS production and NLRP3 inflammasome activation in cultured, activated macrophages, and (5) inhibited ROS production and MCP-1 protein levels in cultured, activated mesangial cells. The results suggest that osthole exerts its reno-protective effects on the progression of IgAN by inhibiting ROS production and activation of NF-κB and the NLRP3 inflammasome in the kidney. Our data also confirm that ROS generation and activation of NF-κB and the NLRP3 inflammasome are crucial mechanistic events involved in the progression of the renal disorder.

Does angiotensin blockade influence graft outcome in renal transplant recipients with IgA nephropathy?

BACKGROUND

IgA nephropathy (IgAN) is a frequent cause of end-stage renal disease (ESRD) and recurrent disease causes deterioration and graft loss in transplant recipients. No definitive management is known to reduce the risk or severity of recurrent IgAN, and the evidence to support the use of renin-angiotensin system blockade in such patients is limited.

METHODS

All 1137 renal transplants performed at the Belfast City Hospital over a 27-year period were reviewed. A total of 75 patients with ESRD due to biopsy-proven IgAN were identified; 39 of them had been prescribed an angiotensin-converting enzyme inhibitor (ACEi) or angiotensin-II type I receptor blocker (ARB).

RESULTS

The two groups were well-matched in terms of demographic details, immunosuppressive regimens and duration of follow-up (median 65 months, range 18-261 months). The 5- and 10-year graft survivals were higher in those prescribed ACEi/ARB therapy compared with those who were not, although these differences did not reach statistical significance (92.9 vs 86.5%; P = 0.34 and 81.6 vs 72.7%; P = 0.32, respectively). These results were similar when censored for death with a functioning graft. In the group where an ACEi/ARB was not prescribed, all four with biopsy-proven recurrent IgAN progressed to ESRD, compared with three out of nine in the group treated with an ACEi/ARB.

CONCLUSIONS

In transplant recipients with ESRD due to biopsy-proven IgAN, a trend towards improved 5-year and 10-year graft survival was seen in those prescribed ACEi/ARBs. All with recurrent IgAN in their grafts who were not treated with ACEi/ARB therapy progressed again to ESRD.

IgA Nephropathy in Kidney Allograft Recipients—Therapeutic Perspective

INTRODUCTION

A growing number of patients are losing their kidney allografts due to glomerulonephritis. Although posttransplant IgA nephropathy (IgAN) is regarded as benign, it may lead to late allograft loss in a substantial number of patients. The aim of this study was to evaluate the influence of posttransplant IgAN on long-term transplantation outcomes, risk factors for progression of graft dysfunction, and effectiveness of therapeutic interventions.

PATIENTS AND METHODS

We evaluated, potential risk factors for accelerated graft loss among 27 kidney allograft recipients with posttransplant IgAN, comparing graft survival in a control group matched for population and transplantation-related parameters. We evaluated the effectiveness of therapeutic interventions regarding immunosuppressive regimen, and hypertension control including angiotensin converting enzyme inhibitor (ACEI) usage with Kaplan-Meier, Cox proportional hazard plots, and log-rank tests in statistical analyses.

RESULTS

Compared with the control group, patients with IgAN experienced a 6.57 higher risk for dialysis dependence (P < .01, 95% CI 1.4 to 30.83). The risk for accelerated graft loss in the course of IgAN was associated with graft dysfunction (RR = 2.16 for additional 1 mg/dL of serum creatinine at glomerulonephritis presentation; P < .03, 95% CI 1.2 to 4.36) and intense proteinuria as evidenced by a RR = 4.67 for the presence of the nephrotic syndrome (P < .05, 95% CI 0.95 to 22.8). Immunosuppression enhancement resulted in a significantly decreased risk of dialysis dependence, namely, RR = 4.76 (95% CI 1.12 to 20, P < .04). With ACEI treatment there was a tendency for a 2.8-fold decreased risk of dialysis dependence, without reaching statistical significance (P = .14).

CONCLUSIONS

Patients with posttransplant IgAN may benefit from intensifying maintenance immunosuppression, which slows progression to end-stage graft dysfunction.

Recurrent IgA nephropathy after renal transplantation despite immunosuppressive regimens with mycophenolate mofetil

BACKGROUND

Transplantation offers an excellent option for patients with immunoglobulin-A nephropathy (IgAN) with severe renal dysfunction. However, IgAN frequently recurs in allografts treated with azathioprine. We examined the impact of mycophenolate mofetil immunosuppression on recurrence of IgAN.

METHODS

We reviewed the charts of patients transplanted for IgAN at our institution in the cyclosporin era. Patients were excluded from further analysis if follow-up was <12 months or if immunosuppression at engraftment did not include azathioprine or mycophenolate mofetil. Laboratory data, medications and allograft biopsy findings were compiled.

RESULTS

152 kidney transplantations met the study criteria. At engraftment, 61 allografts were treated with azathioprine and 91 with mycophenolate mofetil. By 3 years post-transplant, IgAN developed in six of 60 (10.0%) azathioprine-treated allografts and five of 62 (8.1%) mycophenolate mofetil-treated allografts (P = 0.76). Overall, 13 azathioprine-treated and seven mycophenolate mofetil-treated allografts showed recurrence. As expected in this retrospective study, the duration of observation was longer in the azathioprine group. The interval between engraftment and diagnosis of recurrent disease was also longer. Survival of allografts with recurrent IgAN was similar in the two groups. Survival of allografts with recurrent IgAN was worse than for allografts without recurrence or allografts transplanted into patients with non-IgAN renal failure. Neither switching azathioprine to mycophenolate mofetil nor using an angiotensin-converting enzyme inhibitor or angiotensin-II type 1 receptor blocker ameliorated the clinical course after a biopsy documented recurrent IgAN.

CONCLUSIONS

Mycophenolate mofetil, compared with azathioprine, did not lessen the recurrence of IgAN or its clinical impact.

Docosahexaenoic acid attenuates mycotoxin-induced immunoglobulin a nephropathy, interleukin-6 transcription, and mitogen-activated protein kinase phosphorylation in mice

The purpose of this investigation was to evaluate the dose-dependent effects of docosahexaenoic acid (DHA) on deoxynivalenol (DON)-induced IgA nephropathy in mice and their relation to proinflammatory gene expression and mitogen-activated protein kinase (MAPK) activation. Consumption of a modified AIN-93G diet containing 1, 5, and 30 g/kg DHA resulted in dose-dependent increases of DHA in liver phospholipids with concomitant decreases in arachidonic acid compared with control diets. DHA dose dependently inhibited increases in serum IgA and IgA immune complexes (IC) as well as IgA deposition in the kidney in DON-fed mice; the 30 g/kg DHA diet had the earliest detectable effects and maximal efficacy. Both splenic interleukin-6 (IL-6) mRNA and heterogeneous nuclear RNA (hnRNA), an indicator of IL-6 transcription, were significantly reduced in DON-fed mice that consumed 5 and 30 g/kg DHA; a similar reduction was observed for cyclooxygenase (COX-2) mRNA. In a subsequent study, acute DON exposure (25 mg/kg body weight) induced splenic IL-6 mRNA and hnRNA as well as COX-2 mRNA in mice fed the control diet, whereas induction of both RNA species was significantly inhibited in mice fed 30 g/kg DHA. These latter inhibitory effects corresponded to a reduction in DON-induced phosphorylation of p38, extracellular-signal related kinase 1/2, and c-Jun N-terminal kinase 1/2 MAPKs in the spleen. Taken together, the results indicate that DHA dose-dependently inhibited DON-induced IgA dysregulation and nephropathy, and that impairment of MAPK activation and expression of COX-2 and IL-6 are potential critical upstream mechanisms.

Docosahexaenoic acid and eicosapentaenoic acid, but not alpha-linolenic acid, suppress deoxynivalenol-induced experimental IgA nephropathy in mice

Diets enriched in the (n-3) PUFAs, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and their precursor alpha-linolenic acid (ALA), were evaluated for efficacy in ameliorating the development of IgA nephropathy (IgAN) induced in mice by the mycotoxin deoxynivalenol (DON). The effects of DON were compared in mice that were fed for 18 wk with AIN-93G diets containing 1) 10 g/kg corn oil plus 60 g/kg oleic acid (control); 2) 10 g/kg corn oil plus 35 g/kg oleic acid and 25 g/kg DHA-enriched fish oil (DHA); 3) 10 g/kg corn oil plus 33 g/kg oleic acid and 27 g/kg EPA-enriched fish oil (EPA); and 4) 10 g/kg corn oil plus 37 g/kg oleic acid and 23 g/kg DHA + EPA (1:1) enriched fish oil (DHA + EPA). The DHA, EPA and DHA + EPA diets attenuated induction by dietary DON (10 mg/kg) of serum IgA and IgA immune complexes, kidney mesangial IgA deposition, and ex vivo IgA secretion by spleen cells. Consumption of the DHA + EPA diet for 8 wk significantly abrogated the DON-induced gene expression of interleukin (IL)-6, a requisite cytokine for DON-induced IgA nephropathy, in spleen and Peyer's patches. Finally, incorporation of ALA-containing flaxseed oil up to 60 g/kg in the AIN-93G diet did not affect DON-induced IgA dysregulation in mice. Taken together, both DHA and EPA, but not ALA, ameliorated the early stages of IgAN, and these effects might be related to a reduced capacity for IL-6 production.

Renal transplantation in patients with primary immunoglobulin A nephropathy

BACKGROUND

Opinions on the clinical course and outcome of renal transplantation in patients with primary immunoglobulin A nephropathy (IgAN) have been controversial.

METHODS

We conducted a retrospective single-centre study on 542 kidney transplant recipients over the period 1984-2001. Long-term outcome and factors affecting recurrence in recipients with primary IgAN were analysed.

RESULTS

Seventy-five patients (13.8%) had biopsy-proven IgAN as the cause of renal failure, and their mean duration of follow-up after transplantation was 100 +/- 5.8 months. Fourteen (18.7%) of the 75 patients had biopsy-proven recurrent IgAN, diagnosed at 67.7 +/- 11 months after transplantation. The risk of recurrence was not associated with HLA DR4 or B35. Graft failure occurred in five (35.7%) of the 14 patients: three due to IgAN and two due to chronic rejection. Three (4.9%) of the 61 patients without recurrent IgAN had graft failure, all due to chronic rejection. Graft survival was similar between living-related and cadaveric/living-unrelated patients (12-year graft survival, 88 and 72%, respectively, P = 0.616). Renal allograft survival within the first 12 years was better in patients with primary IgAN compared with those with other primary diseases (80 vs 51%, P = 0.001). Thereafter, IgAN patients showed an inferior graft survival (74 vs 97% in non-IgAN patients, P = 0.001).

CONCLUSIONS

Our data suggested that around one-fifth of patients with primary IgAN developed recurrence by 5 years after transplantation. Recurrent IgA nephropathy in allografts runs an indolent course with favourable outcome in the first 12 years. However, the contribution of recurrent disease to graft loss becomes more significant on long-term follow up.

Prognostic factors in immunoglobulin-A nephropathy

AIM

To study the course, identify prognostic factors and a model predictive for development of end stage renal failure (ESRF) in adults with immunoglobulin-A nephropathy (IgA-N).

DESIGN

Retrospective cohort.

SETTING

Madras Medical College and Government General Hospital, Chennai, Tamil Nadu.

PARTICIPANTS

Ninety eight adult patients with diagnosis of primary IgA nephropathy.

RESULTS

Out of 98 patient 64 (65.3%) were men. Mean age of presentation was 25.7 years. The predominant renal lesions included nephrotic syndrome in 25 (25.5%), rapidly progressive renal failure and accelerated malignant hypertension in 21 (21.4%) each, chronic renal failure in 13 (13.3%), hypertension in nine (9.2%) haematuria in five (5.1%) and acute renal failure in four (4.1%). Sixty (61%) had renal failure at diagnosis. Age > 25 years, glomerular histology of Hass subclass V and interstitial fibrosis were significant factors. Forty (48.2%) (IR) patients developed ESRF during follow up. Serum creatinine > 5 mg/dl (hazard ratio: 5.37, 95% confidence interval CI 2.49-11.58) Hass-V (3.74, 1.60-8.76), crescents (4.08, 1.52-10.94) and IF (6.15, 2.0-19.0) were associated with disease progression in the multivariate analysis. Five years renal survival (CI) was 38.5% (24.6%-52.3%). Among those with no risk factor, 95% had not reached ESRF by 42 months. The median ESRF-free survival with one, two and three or four risk factors was 65, 16 and four months, respectively.

CONCLUSIONS

Serum creatinine > 5 mg/dl, crescents: Hass-V histology and interstitial fibrosis predict the progression to ESRF. Renal biopsies should include a detailed assessment of the tubulointerstitium.

Dietary fish oil suppresses experimental immunoglobulin a nephropathy in mice

Dietary fish oil (FO) supplementation reportedly retards the progression of renal disease in patients with immunoglobulin (Ig)A nephropathy (IgAN), the most common glomerulonephritis worldwide. Using an experimental mouse model in which early immunopathological hallmarks of IgAN are induced by the mycotoxin vomitoxin (VT), the ameliorative effects of FO ingestion on this disease were evaluated in two studies. In Study 1, the capacity of VT to induce IgAN was evaluated in mice fed for 12 wk AIN-76A diets containing 50 g/kg corn oil (CO), 50 g/kg CO plus 9 mg/kg tert butylhydroquinone (TBHQ), or 5 g/kg CO plus 45 g/kg menhaden FO that contained 200 mg/kg TBHQ. Serum IgA, serum IgA immune complexes and kidney mesangial IgA deposition were greater in mice fed VT + CO compared with the CO control group, whereas all three variables were significantly attenuated in mice fed VT + FO. Although TBHQ also had attenuating effects, these were significantly less than those for the VT + FO group. In Study 2, the effects of feeding modified AIN 93G diets containing either 70 g/kg CO or 10 g/kg CO plus 60 g/kg FO for 20 wk on VT-induced IgAN were compared. Again, consumption of FO attenuated all three immunopathological variables. In addition, spleen cell cultures from the VT + FO group produced markedly less IgA than those cultures from mice fed VT + CO. Taken together, the results suggested that diets containing FO may impair early immunopathogenesis in VT-induced IgAN and that this was not totally dependent on the presence of the antioxidant TBHQ.

Role of dietary fish oil supplementation in IgA nephropathy. Mechanistic implications

IgA nephropathy (IgAN) is now recognized as the most common primary glomerulonephritis worldwide. Although the clinical course is variable, many patients develop slowly progressive renal disease, culminating in end-stage renal disease 10-20 years after diagnosis. Some recent randomized clinical trials have suggested that dietary fish oil supplementation may be a relatively safe long-term therapeutic option for preventing the development of progressive renal disease in patients with IgAN. However, other studies have failed to demonstrate a protective effect of dietary fish oil supplementation in treatment of IgAN. Although in vitro studies have provided a theoretical basis for the use of dietary fish oil supplementation, potential mechanisms underlying the protective effect of fish oil have not been well defined. In this overview, recent clinical and experimental data providing a basis for the use of dietary fish oil supplementation in treatment of IgAN and other progressive renal diseases are reviewed.

Anti-CD8 monoclonal antibody protects against spontaneous IgA nephropathy in ddY mice

We investigated the effects of anti-CD4 monoclonal antibody (mAb) and/or anti-CD8 mAb in ddY mice, an animal model of spontaneous IgA nephropathy. Female ddY mice were treated with 18 intravenous injections of anti-CD4 and/or anti-CD8 mAb at 2-week intervals. This was based on our observation that a single injection of anti-CD4 mAb or anti-CD8 mAb caused a selective depletion in CD4+ T cells for 2 weeks and CD8+ T cells for 4 weeks, respectively. The level of proteinuria, serum IgA, and changes in the histopathological features of renal tissue samples were assessed in treated mice between the age of 4 and 40 weeks. The level of proteinuria increased with age, but there was not significant difference among the groups. No animal developed microhematuria throughout the study. Treatment with anti-CD4 mAb produced a mild to moderate level of mesangial hypertrophy at 20 and 40 weeks, similar to the results in untreated mice. The lowest degree of mesangial hypertrophy occurred in mice treated with anti-CD8 mAb up to the age of 40 weeks. Treatment with a combination of anti-CD4 and anti-CD8 mAbs produced effects that were similar to those observed on treatment with anti-CD8 mAb alone. Our results suggest that CD8+ T cells mediate mesangial proliferation and the progression of nephropathy in ddY mice.

[Comparative study of the reno-protective effect of short- and long-acting antihypertensive agents in IgA nephropathy]

The progression of IgA-NP is influenced unfavourably by development and existence of hypertension. The treatment of hypertension (HTN) has an important role in these patients. Both short- and long-acting formulations of angiotensin convertase enzim inhibitors (ACEi) and calcium channel blockers (CCB) lower blood-pressure, however long-acting preparations may provide better control and may have more renoprotective effect. Verifying this hypothesis, 22 IgA-NP patients were followed for 7.25 +/- 2.36 years. The patients were on short-acting ACEi (captopril, n = 9) or dihydropyridine type CCB (nifedipin, n = 2) or both (captopril + nifedipine n = 11), after at least 3 years the medication was changed to long-acting ACEI (enalapril, n = 4; cilazapril, n = 1), or non dihydropyridine type CCB (diltiazem hydrochlorid, n = 1) or both (n = 16). Just before changing the medication these patients underwent 24 hour ambulatory blood pressure monitoring and at the same time the level of proteinuria and the creatine clearance were measured. Values of serum-creatinine were measured in every 3-4 months within a 3 years period before and after the exchange of antihypertensive drugs. The regression of 1/creatinine was a = -5.28.10(-5) +/- 1.16.10(-4) before and a = 1.03.10(-4) +/- 2.05.10(-4) after the change of medication. Using paired t-test there was a significant difference between the regressions of 1/creatine (p < 0.005). Systolic blood pressure (SBP) (128 +/- 81 Hgmm vs. 126.09 +/- 11.67 Hgmm) was not different, however, diastolic blood pressure (DBP) (84.15 +/- 7.94 Hgmm vs. 79.78 +/- 7.17 Hgmm), diastolic percent time elevation index (HTI) (43.58 +/- 23.57% vs. 25.61 +/- 20.1%) and 24-hour diastolic hyperbaric impact (114.71 +/- 81.9 vs. 51.51 +/- 51.4, p < 0.05) was lower with long-acting antihypertensive agents, as was the proteinuria (1.18 +/- 0.94 g/die vs. 0.69 +/- 1.08 g/die, p < 0.05). Diurnal variation and systolic percent time elevation index were not different. We conclude that long-acting ACEi and non dihydropyridine type CCB formulations result in better outcomes in IgA nephropathy patients compared to short-acting drugs, probably because of better and smoother blood pressure control, lowering of proteinuria and better compliance of the patients.

Tonsillectomy does not prevent a progressive course in IgA nephropathy

BACKGROUND

IgA nephropathy, or Berger's disease, is a primary mesangioproliferative glomerulonephritis, usually with a favourable prognosis.

PATIENTS AND METHODS

To investigate the effect of tonsillectomy we conducted a retrospective investigation on renal outcome in 55 patients with IgA nephropathy in an outpatient university clinic between 1968 and 1994. Established risk factors for progressive IgA nephropathy were equally distributed in 16 patients subjected to tonsillectomy and in 39 patients without tonsillectomy. Renal survival and impact of risk factors were estimated by Kaplan-Meier analysis and Cox regression model.

RESULTS

Seen in terms of the bivariate Kaplan-Meier analysis the probability of renal survival 10 years after biopsy was 0.37 for the 16 patients with tonsillectomy and 0.63 for the 39 patients without tonsillectomy (log-rank test p = 0.49, not significant). In the multivariate Cox regression model with 6 independent clinical covariates, initially high serum creatinine concentration had the strongest impact on renal outcome (p = 0.002), with a hazard ratio of 8.9 (95% CI: 2.3-35.0). Tonsillectomy had no significant influence in the Cox model (p = 0.37), displaying a hazard ratio of 1.7 (95% CI: 0.5-5.7).

CONCLUSION

In conclusion, tonsillectomy does not reduce the risk of developing renal failure or prevent a progressive course of IgA nephropathy.

Prognosis of tonsillectomy in patients with IgA nephropathy

IgA nephropathy (IgAN) is a type of chronic glomerulonephritis characterized by IgA deposits mainly in the mesangial area. It does not have so favourable a prognosis as was initially thought. This nephropathy is one of the diseases affected by tonsillar focal infections, and there have been patients in whom tonsillectomy has been effective. In this study, 24 patients with IgAN were followed for more than 2 years after tonsillectomy and studied clinicopathologically. Remission of proteinuria was observed in 41.7% of the patients 6 months after surgery and in 50.0% 2 years after surgery. At 2 years after surgery, patients with minor and focal segmental renal lesions showed a significantly higher rate of remission of proteinuria than patients with diffuse renal lesions. There was no statistically significant difference between positive and negative patients in the rate of remission of proteinuria based on any parameter of the tonsillar provocation test at any time after surgery.

Effects of fish oil and alpha-tocopherol in immunoglobulin A nephropathy in the rat

Alpha-tocopherol and fish oil have been reported to modulate the progression of IgA nephropathy in animals and humans. Because fish oil has been reported to exacerbate renal disease in subtotal nephrectomized rats, we investigated the effects of fish oil, with and without alpha-tocopherol, on the course of IgA nephropathy. Experimental IgA nephropathy was induced in male Sprague-Dawley rats, weighing 170-200 g, by oral and i.v. immunization with bovine gamma-globulin for 8 wk. IgA nephropathy was evidenced by hematuria, proteinuria, and IgA deposition in the mesangium. Standard rodent chow, containing 30 IU of alpha-tocopherol/kg of diet, was given to the control and IgA nephropathy rats. Fish oil (20% wt/wt), stripped of alpha-tocopherol preservative, was given to control and a second group of IgA nephropathy rats. Alternatively, corn oil or fish oil was supplemented with alpha-tocopherol at 100 IU/kg of diet and given to the third and fourth groups of IgA nephropathy rats. All animals were killed at 8 wk. Urinary protein excretion, plasma and kidney alpha-tocopherol concentrations, as well as glomerular planar area, and kidney transforming growth factor-beta1 mRNA were analyzed. As determined by reductions in proteinuria, glomerular planar area, and TGF-beta1 mRNA, fish oil with alpha-tocopherol ameliorated the renal injury induced by bovine gamma-globulin, whereas fish oil without alpha-tocopherol did not. Our findings support the importance of alpha-tocopherol, more so than fish oil, in mitigating the injury and promoting repair in experimental IgA nephropathy.

Vitamin E ameliorates renal injury in an experimental model of immunoglobulin A nephropathy

IgA nephropathy is one of the most common forms of glomerular disease. Nearly 25% of affected patients progress to end-stage renal disease over a 20-25-y follow-up period. IgA-containing immune complexes stimulate oxygen-free radical production by mesangial cells in vitro. The excessive oxidant stress may mediate glomerular injury in this disorder. Therefore, we studied whether dietary supplementation with the antioxidant agent, vitamin E, attenuates renal disease in an experimental model of incipient IgA nephropathy with mild kidney inflammation. IgA nephropathy was induced in male Lewis rats by oral immunization with 0.1% bovine gamma-globulin (BGG)-containing drinking water for 8 wk. At the completion of this period, animals received BGG, 1 mg/dose i.v., on three successive days. Experimental rats (n = 10) received a specially formulated diet containing 100 IU of vitamin E/kg of chow, whereas control animals (n = 10) were fed chow containing 30 IU of vitamin/kg of chow. The BGG immunization regimen induced mesangial IgA deposition in all rats. Vitamin E supplementation resulted in a nearly 5-fold increase in the serum vitamin E concentration. Vitamin E-treated rats gained more weight and had a lower incidence of hematuria, 20% versus 80% (p < 0.03). Moreover, proteinuria was decreased by 50%, and reduced renal plasma flow was restored to normal, compared with untreated rats with IgA nephropathy. Glomerular hypertrophy occurred in animals with IgA nephropathy, but less so in those receiving vitamin E supplementation. Renal cortical malondialdehyde content was reduced from 1.55 +/- 0.10 to 1.22 +/- 0.09 nmol/mg of protein (p < 0.01) in rats fed the vitamin E-enriched diet. Finally, renal transforming growth factor-beta 1 gene expression was reduced by 34% in rats with IgA nephropathy receiving vitamin E treatment (p < 0.05). We conclude that experimental IgA nephropathy is associated with increased renal oxidant injury. Dietary treatment with the antioxidant agent, vitamin E, attenuated renal functional and structural changes in this experimental glomerulopathy. These studies support the importance of clinical trials for the evaluation of the efficacy of antioxidant therapy in patients with IgA nephropathy.

Monomeric immunoglobulin A protects glomerulus against polymeric immunoglobulin A immune complex in experimental immunoglobulin A nephropathy

Polymeric (p) IgA constitutes 13% of total serum IgA, whereas monomeric (m) IgA represents the other 87%. pIgA tends to form complexes in the circulation that eventually localize in the glomerulus. mIgA is a nonprecipitable antibody. When complexed with an antigen in vivo, the circulating mIgA immune complex (IC) thus formed does not deposit in the glomerulus. The purpose of the present study was to evaluate the influence of mIgA on the formation of pIgA-lC and subsequent glomerular deposition of the IC in an experimental model of IgA nephropathy. The influence of mIgA anti-dinitrophenyl (DNP) on pIgA anti-DNP/DNP-conjugated BSA (BSA-DNP) IC formation was assessed by double diffusion test and competition PAGE in combination with autoradiography. Only the BSA-DNP, a model antigen of relatively low molecular mass, was radiolabeled and monitored throughout the latter experiment. An analysis of clearance kinetics (1 and 6 hours) of the antigen using 4-week-old female BALB/c mice, and a series of renal studies were performed after intravenous injection with a single dose of combined pIgA anti-DNP, BSA-DNP, and mIgA anti-DNP. As demonstrated by the double diffusion test, addition of mIgA anti-DNP resulted in suppression of the precipitating reaction of pIgA anti-DNP and BSA-DNP. This effect was confirmed by PAGE for size determination of the BSA-DNP which had been complexed with either pIgA anti-DNP or a mixture of pIgA anti-DNP and mIgA anti-DNP. The clearance kinetics studies showed that the elimination of BSA-DNP injected with pIgA anti-DNP was prolonged in the presence of mIgA anti-DNP in a partially dose-dependent manner. The experimental mice receiving pIgA anti-DNP, BSA-DNP, and mIgA anti-DNP showed less hematuria (p < 0.005) than mice receiving pIgA anti-DNP and BSA-DNP (positive control) when examined 1 hour after injection. Immunofluorescence study of the renal tissue of mice receiving pIgA anti-DNP, BSA-DNP, and mIgA anti-DNP showed a suppressed glomerular localization of IgA and third component of complement, as compared with those injected with pIgA anti-DNP and BSA-DNP alone. Similarly, a significant decrease of glomerular BSA-DNP deposits was observed in mice receiving pIgA anti-DNP, BSA-DNP, and mIgA anti-DNP compared with those receiving pIgA anti-DNP and BSA-DNP alone, as demonstrated by light microscopic autoradiography. These findings indicate that a high dose of specific mIgA was capable of modulating glomerular deposition of the pIgA-IC in this animal model of IgAN.

Suppression of glomerular IgA deposition in ddY mice through periodic injections of lipopolysaccharides

We investigated the role of lipopolysaccharides (LPS) in glomerular IgA deposition of ddY mice. The incidence of IgA deposition was lower in the LPS-injected mice at 10 and 13 months of age as compared with that of their age-matched controls (10 months, LPS 20% vs control 60%; 13 months, LPS 14% vs control 100%). Serum levels of IgA were lower in the LPS-injected mice than in the control mice. There were no appreciable differences in the percentage value of Thy-1+ cells, the ratio of Lyt-1+/Lyt-2+ cells, mitogenic responses, or IL-1 activities between the LPS-injected and the control mice. On the other hand, the IgA responses of spleen and Peyer's patch cells in the LPS-injected mice were lower than those observed in the control mice. These results suggest that the persistent use of LPS directly suppresses gut-associated lymphoreticular tissue (GALT), and that the lower IgA response in GALT induced by LPS causes suppression of glomerular IgA deposition in ddY mice.

Lessons learned from the Japanese nephritis screening study

A program of urine screening for asymptomatic hematuria and proteinuria in school children has been conducted since 1973 by the Ministry of Education in Japan with great success in the early detection of asymptomatic renal disease. In order to know whether this nationwide program during 13 years has contributed to understanding of the epidemiology of chronic glomerular disease in Japan, a multicenter survey of the patients was conducted. Between 70% and 80% of IgA and non-IgA mesangial proliferative glomerulonephritis and 65%-80% of membrano-proliferative glomerulonephritis (MPGN) were detected by mass urine screening at school. Severe glomerular lesions were more frequently observed in children with chance proteinuria and hematuria, as well as IgA and non-IgA mesangial proliferative glomerulonephritis with significant proteinuria. Mild glomerular change was more frequent in patients with MPGN, IgA and non-IgA mesangial proliferative nephritis with minimal proteinuria who were detected by our screening program, rather than those seen with some of the nephritic signs and symptoms at diagnosis. The above evidence suggests that a screening program may open the way for the early management of these diseases, especially where treatment is already established.

Effect of sodium cromoglycate on an experimental model of IgA nephropathy

Recently, we reported on an experimentally-induced model of IgA nephropathy in mice, in which the lesions were very similar to those found in human IgA nephropathy. This model was achieved by long-term oral immunization and intravenous injection of colloidal carbon in order to achieve reticuloendothelial (RES) dysfunction. In this paper, we investigated the effects of sodium cromoglycate (SCG), an anti-allergic agent, on this model. Mice were treated with a small amount of colloidal carbon three times to block the RES, in addition to receiving oral administration of lactalbumin, as a food antigen. Open renal biopsy was performed at 18 weeks after the RES blockade, and mice were divided into 2 groups. One group received orally administered SCG and lactalbumin [SCG(+)], and the other group received lactalbumin only [SCG(-)] from 19 to 30 weeks. At 30 weeks, all mice were sacrificed for histopathological observation of renal tissue and blood sampling. IgA nephropathy had developed in all mice of the SCG(-) group, but had not developed in 7 out of the 9 mice in the SCG(+) group, at 30 weeks. Serum IgA levels obtained on sacrifice were significantly higher in the SCG(-) group. It was concluded that SCG effectively inhibited, not only the onset, but also the progression of IgA nephropathy in our original model. The effective mechanisms of this drug may act to suppress the local immunity produced through sensitization of gastrointestinal mucosa by food antigens.