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.

n-3 Fatty acids and their role in nephrologic practice.

During the past year, a newly reported clinical trial has strengthened the argument for recommending daily treatment with n-3 polyunsaturated fatty acids in patients with immunoglobulin A nephropathy (the most common form of primary glomerulonephritis in the world) who are at high risk for progression of renal disease. Studies are underway that involve a combination of cyclosporine A, a commonly prescribed immunosuppressive agent in solid-organ transplantation, with a high-potency n-3 polyunsaturated fatty acid to reduce cyclosporine toxicity. Two studies reported during the past year show promise that dietary supplementation with n-3 polyunsaturated fatty acids will substantially decrease vascular access graft thrombosis in patients receiving maintenance hemodialysis, and may reduce hypercalciuria in patients who suffer from kidney stones.

The emerging role of omega-3 polyunsaturated fatty acids in the management of patients with IgA nephropathy.

Immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis in the world, affects mostly young adults, and shows a widely variable clinical course with many patients developing progressive renal disease, culminating in terminal renal failure in 20% to 40% of those afflicted. Until recently, no treatment options have been available for IgAN. Although a cure for the disease remains elusive, drugs that slow disease progression are becoming available, including omega-3 (n-3) fatty acids. The largest long-term clinical trial evaluating n-3 fatty acids in high-risk patients with IgAN showed that early and prolonged treatment with n-3 fatty acids retards renal progression. The rationale for using these fats involves potential mechanisms that reduce renal inflammation and glomerulosclerosis, hallmarks of progressive disease.

Suppressive effects of fish oil on mesangial cell proliferation in vitro and in vivo.

BACKGROUND: Mesangial cell proliferation is a characteristic feature of IgA nephropathy and many other forms of glomerulonephritis. Recent clinical studies have shown that dietary fish oil supplementation retards renal disease progression in patients with IgA nephropathy. The mechanism by which this effect occurs is unknown. METHODS: The anti-Thy 1.1 (ATS) model of mesangial proliferative glomerulonephritis was employed to test the hypothesis that dietary fish oil supplementation reduces mesangial cell proliferation following acute injury. Subcultured rat mesangial cells were used to determine the in vitro effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the primary components of fish oil, on proliferation. RESULTS: Following antithymocyte serum (ATS) administration, proteinuria was significantly decreased in animals treated with fish oil compared with sesame oil-treated controls. In ATS rats given fish oil, there was less mesangial cell and matrix expansion, mesangiolysis, or basement membrane disruption (delta% = -40%). ATS rats receiving fish oil had less glomerular cell proliferation (PCNA-delta% = -50%) and a reduction of alpha-smooth muscle actin expression (delta% = -27%) by mesangial cells. In subcultured rat mesangial cells, DHA, but not EPA, significantly inhibited proliferation. CONCLUSIONS: Fish oil inhibits mesangial cell activation and proliferation in ATS glomerulonephritis, reduces proteinuria, and decreases histologic evidence of glomerular damage. In vitro, the antiproliferative effects of fish oil are more likely related to the action of DHA. We suggest that orally administered fish oil, or purified DHA, may have a suppressive effect in acute phases or relapses of glomerulopathies by inhibiting activation and proliferation of mesangial cells.

Use of fish oil to treat patients with immunoglobulin a nephropathy.

This review describes the use of fish oil in the treatment of patients with immunoglobulin (Ig) A nephropathy. IgA nephropathy is the most common glomerular disease worldwide. It has a variable course and leads to end-stage renal disease in a substantial number of cases. Among the 4 published randomized clinical trials that tested the efficacy of fish-oil treatment of IgA nephropathy, 2 reported beneficial effects on renal function and 2 showed negative results. In the largest trial conducted by my collaborative study group, convincing evidence was provided for protection against progressive renal disease after daily treatment for 2 y with fish oil providing 1.8 g eicosapentaenoic acid and 1.2 g docosahexaenoic acid-the 2 major n-3 polyunsaturated fatty acids in fish oil. Oral prednisone has also been advocated, especially in the treatment of children with IgA nephropathy. Two randomized trials are currently underway in the United States to resolve the discrepancy of results in previous fish-oil trials and to determine whether corticosteroids or fish oil is the better treatment of patients at risk for developing progressive disease; results of these studies are not yet available.

Recurrent Goodpasture's disease due to a monoclonal IgA-kappa circulating antibody.

We describe the case of a 54-year-old man who first presented with a clinical syndrome manifested by recurrent pulmonary hemorrhage, hematuria, and mild renal insufficiency. Direct immunofluorescence of renal biopsy sections showed linear deposition of IgA-kappa in the glomerular (GBM) and tubular basement membranes. Serum protein immunoelectrophoresis was positive for a monoclonal immunoglobulin A (IgA)-kappa protein. Serum analysis showed circulating IgA anti-GBM antibodies. Treatment with high-dose steroids, cyclophosphamide, and plasma exchange resulted in resolution of the clinical picture. To the best of our knowledge, this is the first report of Goodpasture's disease associated with the presence of a circulating monoclonal IgA-kappa antibody.

The long-term outcome of patients with IgA nephropathy treated with fish oil in a controlled trial. Mayo Nephrology Collaborative Group.

It was reported previously that dietary fish oil supplementation retarded the progression of renal disease in patients with IgA nephropathy in a multicenter, placebo-controlled, randomized, 2-yr clinical trial. The aim of this study was to determine the long-term influence of fish oil treatment on renal progression in observations on the study cohort of 106 patients extending beyond the 2-yr trial. Renal function was assessed by serial serum creatinine and 24-h urine protein measurements. Vital, end-stage renal disease (ESRD), and BP status and treatment beyond completion of the 2-yr trial were determined. As in the trial, the primary end point was an increase of 50% or more in the serum creatinine, and the secondary end point was ESRD. After a mean follow-up of 6.4 yr, 46 patients-17 in the fish oil group versus 29 in the placebo group-reached the primary end point (P = 0.002), and 27 patients-eight in the fish oil group versus 19 in the placebo group-developed ESRD (P = 0.009). At the end of the 2-yr trial, 75 patients (45 fish oil, 30 placebo) remained at risk for the primary end point. This is also when the double-blind part of the trial ended, allowing physicians to stop supplements, switch original placebo-assigned patients to fish oil, and continue fish oil in original fish oil-assigned patients. A significantly greater number of nonsupplemented placebo patients developed the primary end point (P = 0.02) and ESRD (P = 0.003) compared with long-term supplemented fish oil patients. Conversely, more fish oil-supplemented patients had stable renal function than nonsupplemented patients (P = 0.02). By intention, BP control, primarily treated with angiotensin-converting enzyme inhibition, was equal in the fish oil and placebo groups. Proteinuria was modestly reduced in both groups. It is concluded that early and prolonged treatment with fish oil slows renal progression for high-risk patients with IgA nephropathy.

The fate of renal transplants in patients with IgA nephropathy.

BACKGROUND: IgA Nephropathy (IgA N) is one of the most common glomerulopathies and may lead to renal failure in 10-20% of cases. After renal transplantation, IgA N has a strong tendency to recur in the graft. Initially considered a benign condition, graft losses from recurrent IgA N have been reported over the last 20 yr, casting doubt on the initial premise. Since large single-center studies of the fate of renal allografts in IgA N are rare and the Mayo Clinic transplant experience for IgA N is extensive (dating back to 1970), a review of these issues appeared worthwhile. METHODS: A retrospective study was done of all renal transplant patients who had had biopsy-proven IgA N as underlying disorder. We extracted data on the underlying disease, history leading to renal transplantation, factors affecting transplant outcome, and on the course after transplantation with special attention to rejection activity and recurrence of the primary disease. Standard statistical methods were employed. RESULTS: 53 renal allografts were transplanted to 51 biopsy-proven IgA N patients: 12 were cadaveric (CAD) grafts, 3 HLA-mismatched living related donor (LRD) kidneys, 29 one haplotype-matched LRD and 9 HLA-identical LRD organs. Five-year actuarial graft survival was 100% in HLA-identical LRD, 88% in one haplotype-matched LRD, and 74% in CAD grafts. All three HLA-mismatched LRD kidneys were functioning up to 1.6 yr (longest follow-up). Only one patient died after acute rejection of the CAD graft. There were 3 early graft losses from acute rejection and 4 late losses. IgA N recurred in 26% of allograft and led to significant loss of graft function in 10 of the 14 patients (71%) over a long period of observation. Three of four late graft losses were in patients with recurrent IgA N. Recurrence was not related to the type of graft, i.e. CAD vs. LRD, nor to the extent of HLA-matching in LRD transplantation. CONCLUSION: Renal transplantation in patients with IgA N has excellent patient and graft survival. There is a high rate of recurrence of the primary glomerulopathy in the renal allograft, and this event is by no means inconsequential. Loss of renal function and even graft loss occur over prolonged periods of time. There is no disadvantage getting a well matched LRD in regard to incidence of recurrent IgA N. Thus, we encourage LRD transplantation in IgA N.

Predicting renal outcome in IgA nephropathy.

Immunoglobulin A (IgA) nephropathy, the most common form of glomerulonephritis worldwide, is characterized by a heterogeneous clinical course. In this study, multivariate analysis was performed to identify histopathologic and clinical features that most accurately predict adverse outcome from a dataset of 148 individuals with IgA nephropathy who underwent renal biopsy at our institution between 1973 and 1995. A semiquantitative scoring system was developed for assessment of six glomerular, eight interstitial, and six vascular histopathologic features of IgA nephropathy. Glomerular and interstitial proliferative activity was evaluated by immunostaining archival biopsy specimens with Mib-1, an antibody directed against the Ki-67 antigen. Kaplan-Meier survival analysis was performed, with renal failure being defined as onset of dialysis or transplantation. A number of clinicopathologic factors were univariately associated with adverse outcome, including elevated serum creatinine levels; the presence of hypertension; proteinuria; component and total histopathologic scores; and positive glomerular or interstitial Mib-1 scores. The total glomerular score, consisting of the arithmetic sum of each of the six component scores, was the strongest histopathologic predictor of adverse outcome. Total interstitial and vascular scores also provided more prognostic information than did individual component scores. By multivariate analysis, high total glomerular scores, increased serum creatinine levels at diagnosis, and younger age were significant (P < 0.01) independent predictors of renal failure. Our studies provide a rational basis for the inclusion of composite histopathologic scores in clinical intervention studies of patients with IgA nephropathy and other glomerular disorders.

Reversible membranous nephropathy associated with the use of nonsteroidal anti-inflammatory drugs.

OBJECTIVE: To investigate the frequency of membranous nephropathy associated with nonsteroidal anti-inflammatory drug (NSAID) use and identify associated clinical characteristics. DESIGN: Retrospective chart review. SETTING: A large group practice that staffs 2 large teaching hospitals. PATIENTS: All patients diagnosed as having stage I or early stage II membranous nephropathy by renal biopsy between January 1975 and May 1995. MAIN OUTCOME MEASURES: Nephrotic syndrome was said to be associated with NSAID use if patients developed nephrotic syndrome while taking an NSAID and if other causes of membranous nephropathy were excluded and a rapid remission of the nephrotic syndrome followed withdrawal of the drug. RESULTS: Of 125 patients identified with early membranous nephropathy, 29 were taking NSAIDs at the time symptoms of nephrotic syndrome developed. Thirteen of these patients met the criteria for NSAID-associated membranous nephropathy. None of these patients had any evidence of renal insufficiency or significant proteinuria after follow-up periods ranging from 5 months to 13 years. In addition to diclofenac and fenoprofen, which have previously been implicated, ibuprofen, nabumetone, naproxen, and tolmetin were found to be associated. CONCLUSIONS: Nephrotic syndrome due to membranous nephropathy should be recognized as an idiosyncratic drug reaction to many NSAIDS. Because withdrawal of the drug may result in prompt and complete recovery of normal renal function, a history of NSAID intake should be sought in patients with membranous nephropathy.

Prognostic determinants in lupus nephritis: a long-term clinicopathologic study.

Over the past 50 years, survival has improved in patients with systemic lupus erythematosus and associated nephritis. Yet, there are few long-term outcome studies in patients with well-defined nephropathy. We examined the outcome of 439 patients with lupus nephritis who were seen at the Mayo Clinic between 1964 and 1986 in whom renal biopsies were assessed using the World Health Organization (WHO) classification. There were 341 women and 98 men (mean +/- s.d., age 33.5 +/- 14 years); 200 (46%) patients were hypertensive and 249 (57%) had impaired renal function at renal biopsy. All WHO morphologic classes were represented and 339 (77%) patients had class III, IV and V (the more severe forms of nephritis). Follow-up averaged 10.2 years per patient. At last contact, 286 (65%) patients were alive and 153 (35%) were dead. Overall patient survival was 80%, 69% and 53% at 5, 10 and 20 years after biopsy that was significantly worse than expected survival (P < 0.001). Ten-year cumulative patient survival improved comparing earlier to more recent time spans: 64% in 231 patients seen during 1964-75; 76% in 2089 patients studied during 1976-86 (P = 0.03). Survival free of renal failure was 83%, 74% and 64% at 5, 10 and 20 years, and survival was unfavorably influenced by progressive WHO class, hypertension, impaired renal function, nephrotic range proteinuria, hypoalbuminemia and anemia. Multivariate analysis found impaired renal function, increased urine protein, anemia and younger age to be independent predictors of renal failure. WHO class was not a significant predictor when adjusted for these four factors. Cardiovascular events accounted for 48% of the known deaths and were equally distributed across all WHO classes, followed by infections, renal failure, malignancy, respiratory failure and gastrointestinal bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

A controlled trial of fish oil in IgA nephropathy. Mayo Nephrology Collaborative Group.

BACKGROUND: The n-3 fatty acids in fish oil affect eicosanoid and cytokine production and therefore have the potential to alter renal hemodynamics and inflammation. The effects of fish oil could prevent immunologic renal injury in patients with IgA nephropathy. METHODS: In a multicenter, placebo-controlled, randomized trial we tested the efficacy of fish oil in patients with IgA nephropathy who had persistent proteinuria. The daily dose of fish oil was 12 g; the placebo was a similar dose of olive oil. Serum creatinine concentrations, elevated in 68 percent of the patients at base line, and creatinine clearance were measured for two years. The primary end point was an increase of 50 percent or more in the serum creatinine concentration at the end of the study. RESULTS: Fifty-five patients were assigned to receive fish oil, and 51 to receive placebo. According to Kaplan-Meier estimation, 3 patients (6 percent) in the fish-oil group and 14 (33 percent) in the placebo group had increases of 50 percent or more in their serum creatinine concentrations during treatment (P = 0.002). The annual median changes in the serum creatinine concentrations were 0.03 mg per deciliter (2.7 mumol per liter) in the fish-oil group and 0.14 mg per deciliter (12.4 mumol per liter) in the placebo group. Proteinuria was slightly reduced and hypertension was controlled to a comparable degree in both groups. The cumulative percentage of patients who died or had end-stage renal disease was 40 percent in the placebo group after four years and 10 percent in the fish-oil group (P = 0.006). No patient discontinued fish-oil treatment because of adverse effects. CONCLUSIONS: In patients with IgA nephropathy, treatment with fish oil for two years retards the rate at which renal function is lost.

Essential fatty acid deficiency profiles in idiopathic immunoglobulin A nephropathy.

The profiles of fatty acids (FAs) of plasma phospholipids (the compartment reflecting the essential FA status of tissue lipids), nonesterified FAs (the precursor pool for autacoid synthesis), urine protein excretion, and glomerular filtration rate were measured before and after supplementation with fish oil in 15 patients with immunoglobulin A nephropathy. In the FA profiles, there was deficient 18:3 omega 3 (alpha-linolenic acid), the parent compound of omega 3 polyunsaturated FA, and deficient chain elongation products of both omega 3 and omega 6 polyunsaturated FAs with replacement by saturated and monounsaturated short-chain, odd-chain, and branched-chain FAs, producing significant loss of omega 3 FA. These alterations indicate nutritional or functional (omega 3) and metabolic (omega 6) deficiencies. Additionally, the mean melting point of the FAs was significantly increased, implying an inherent decrease in cell membrane fluidity. Enhancement of 20: 5 omega 3 (eicosapentaenoic acid) and 22:6 omega 3 (docosahexaenoic acid) and suppression of 20:4 omega 6 (arachidonate) after supplementation with fish oil were accompanied by important decreases in proteinuria and improved glomerular filtration rate. Omega-3 polyunsaturated FAs may favorably influence immunoglobulin A nephropathy through a modulation of the pathologic actions of the omega 6 eicosanoids and other diverse actions on various mediators produced by an initial immune injury.

Clinical and histopathologic associations with impaired renal function in IgA nephropathy. Mayo Nephrology Collaborative Group.

A multicenter, double-blind, placebo-controlled, randomized trial of fish oil in proteinuric patients with IgA nephropathy is being conducted by the Mayo Nephrology Collaborative Group. We completed enrollment of 106 patients into the trial in December 1991. The treatment period is for two years. Hypertension is being managed in all patients with enalapril maleate (Vasotec). We evaluated the associations between a variety of clinical and renal morphologic features and renal function at the entry of all enrolled patients. Among 78 males and 28 females [age(mean +/- SD) 36 +/- 14 years], older age at treatment randomization, hypertension, at disease discovery as well as at study entry, increased fractional excretion of albumin, increased serum triglyceride levels, and more severe tubulointerstitial, vascular, and combined glomerular and tubulointerstitial histologic lesions were all univariately associated (p < or = 0.01) with poorer renal function measured by reciprocal serum creatinine and creatinine clearance levels. In a multiple regression analysis used to predict baseline reciprocal creatinine, the best final model (R2 = 0.48) included male sex (p < .001), hypertension at treatment randomization (p = .001), decreased peripheral blood erythrocytes (p = .001), increased tubulointerstitial score (p = .004), and increased fractional excretion of albumin (p = .025) as independent predictors of decreased kidney function. These associations are similar to those seen in the high-risk subset of patients with IgA nephropathy who develop end-stage renal disease. In the eventual outcome analysis of the clinical trial, we will examine the effects of treatment on the two potentially modifiable risk factors, hypertension and proteinuria, on renal function.

Immunosuppressive drug therapy in lupus nephritis.

During the past two decades, the immunosuppressive drugs azathioprine and cyclophosphamide have been widely used in the treatment of patients with lupus nephritis. Their toxicities are well known and are mostly dose- and time-dependent. Complications that arise from these therapies stem from their immunosuppressive (susceptibility for infection) or pharmacologic (hemorrhagic cystitis, bladder cancer, and fibrosis from the alkylating agents) effects, or both. Uncontrolled studies reporting good results in treating patients with various combinations of corticosteroids and azathioprine and, especially, cyclophosphamide cannot be conclusively confirmed by the few controlled clinical trials that are available for review. Part of the problem of inconclusiveness has to do with timing treatment to different phases of the disease and the vast heterogeneity of lupus nephritis. Although these immunosuppressive agents may have favorable effects on the overall activity of systemic lupus erythematosus, their long-term effects per se on renal disease are in question and could be attributed to lower prednisone dosage and better medical management of hypertension, hyperlipidemia, infection, and other metabolic consequences of the disease.