The IgA nephropathy treatment dilemma

Although IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide, our understanding of the pathogenesis of this complex disease remains limited. IgA nephropathy may appear with a variety of clinical presentations, a number of different clinical and histopathologic risk factors for progressive renal disease, and a very variable course over time. Thus, it is not surprising that a single therapeutic treatment plan has not been established. Many of the studies dealing with IgAN are retrospective, lack statistical significance, or have confounding designs, which hinder their general acceptance. Nevertheless, a number of well-designed studies have been performed. This paper reviews currently available therapeutic options for IgAN. It attempts to address several important questions: Why do we treat patients with IgAN? How do we decide which patients should be treated? What are the general treatment guidelines for all IgAN patients? What is the role of specific therapy such as fish oils, tonsillectomy, and immunosuppression in the treatment of patient with IgAN? It also addresses several on-going trials and goals for future therapeutic studies for IgAN patients.

Update on the treatment of lupus nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in patients with systemic lupus erythematosus. Although the use of aggressive immunosuppression has improved both patient and renal survival over the past several decades, the optimal treatment of LN remains challenging. Improved outcomes have come at the expense of significant adverse effects owing to therapy. Moreover with long-term survival, the chronic adverse effects of effective therapies including risk of malignancy, atherosclerosis, infertility, and bone disease all become more important. Finally, some patients fail to achieve remission with standard cytotoxic therapy and others relapse when therapy is reduced. For these reasons, recent clinical trials have attempted to define alternate treatment protocols that appear to be efficacious in achieving and maintaining remission, but with less toxicity than standard regimens. This paper discusses established and newer treatment options for patients with proliferative and membranous LN, with an emphasis on the results of these recent clinical trials. We also review the experimental and human data regarding some of the novel targeted forms of therapy that are under investigation and in different phases of clinical trials.

Mycophenolate Mofetil for the Treatment of Interstitial Nephritis

Acute interstitial nephritis (AIN) is a clinicopathologic entity that is characterized by acute renal failure and renal biopsy findings of interstitial inflammation and tubulitis. There are multiple causes of AIN, the majority of which appear to respond to immunosuppressive therapy. Corticosteroids are the mainstay of treatment for AIN, but many patients are refractory to or intolerant of treatment or are unable to discontinue therapy without clinical relapse. Herein are reported eight cases of steroid-resistant, biopsy-proven AIN that were treated successfully with mycophenolate mofetil (MMF) at one institution. Patients had a mean decline in serum creatinine from 2.3 to 1.6 mg/dl over a mean of 24.3 mo of treatment. Six of the eight patients had a decline in serum creatinine of at least 0.3 mg/dl, and the remaining two patients had stable renal function during the treatment period. At most recent follow-up, five of the eight patients successfully have discontinued treatment with MMF for a mean of 6.4 mo. MMF was well tolerated by all patients. It is concluded that MMF is a useful therapeutic option for steroid-resistant AIN and may be considered as potential first-line therapy in select populations.

Improved outcomes in nephrotic syndrome

Nephrotic syndrome can now be treated effectively in most cases. All patients should be treated with a low-salt diet, diuretics to reduce edema, and statins to normalize serum lipid concentrations. Patients with nephrotic syndrome are prone to deep vein thrombophlebitis, renal vein thrombosis, and pulmonary emboli. Depending on the condition, additional treatment may include corticosteroids, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), cyclosporine, cytotoxic agents, or mycophenolate.

Mycophenolate mofetil or intravenous cyclophosphamide for lupus nephritis

BACKGROUND

Since anecdotal series and small, prospective, controlled trials suggest that mycophenolate mofetil may be effective for treating lupus nephritis, larger trials are desirable.

METHODS

We conducted a 24-week randomized, open-label, noninferiority trial comparing oral mycophenolate mofetil (initial dose, 1000 mg per day, increased to 3000 mg per day) with monthly intravenous cyclophosphamide (0.5 g per square meter of body-surface area, increased to 1.0 g per square meter) as induction therapy for active lupus nephritis. A change to the alternative regimen was allowed at 12 weeks in patients who did not have an early response. The study protocol specified adjunctive care and the use and tapering of corticosteroids. The primary end point was complete remission at 24 weeks (normalization of abnormal renal measurements and maintenance of baseline normal measurements). A secondary end point was partial remission at 24 weeks.

RESULTS

Of 140 patients recruited, 71 were randomly assigned to receive mycophenolate mofetil and 69 were randomly assigned to receive cyclophosphamide. At 12 weeks, 56 patients receiving mycophenolate mofetil and 42 receiving cyclophosphamide had satisfactory early responses. In the intention-to-treat analysis, 16 of the 71 patients (22.5 percent) receiving mycophenolate mofetil and 4 of the 69 patients receiving cyclophosphamide (5.8 percent) had complete remission, for an absolute difference of 16.7 percentage points (95 percent confidence interval, 5.6 to 27.9 percentage points; P=0.005), meeting the prespecified criteria for noninferiority and demonstrating the superiority of mycophenolate mofetil to cyclophosphamide. Partial remission occurred in 21 of the 71 patients (29.6 percent) and 17 of the 69 patients (24.6 percent), respectively (P=0.51). Three patients assigned to cyclophosphamide died, two during protocol therapy. Fewer severe infections and hospitalizations but more diarrhea occurred among those receiving mycophenolate.

CONCLUSIONS

In this 24-week trial, mycophenolate mofetil was more effective than intravenous cyclophosphamide in inducing remission of lupus nephritis and had a more favorable safety profile.

Mutational and Biological Analysis of α-Actinin-4 in Focal Segmental Glomerulosclerosis

Mutations in the alpha-actinin-4 gene (ACTN4) cause an autosomal dominant form of focal segmental glomerulosclerosis (FSGS). A mutational analysis was performed of ACTN4 in DNA from probands with a family history of FSGS as well as in individuals with nonfamilial FSGS. The possible contribution of noncoding variation in ACTN4 to the development of FSGS also was assessed. Multiple nucleotide variants were identified in coding and noncoding sequence. The segregation of nonsynonymous coding sequence variants was examined in the relevant families. Only a small number of nucleotide changes that seemed likely to be causing (or contributing to) disease were identified. Sequence changes that predicted I149del, W59R, V801M, R348Q, R837Q, and R310Q changes were identified. For studying their biologic relevance and their potential roles in the pathogenesis of FSGS, these variants were expressed as GFP-fusion proteins in cultured podocytes. F-actin binding assays also were performed. Three of these variants (W59R, I149del, and V801M) showed clear cellular mislocalization in the form of aggregates adjacent to the nucleus. Two of these mislocalized variants (W59R and I149del) also showed an increased actin-binding activity. The I149del mutation segregated with disease; W59R was found to be a de novo mutation in the proband. A total of five ACTN4 mutations that are believed to be disease causing (three reported previously and two novel) as well as a number of variants with unclear contribution to disease now have been identified. The possibility that some of these other variants increase the susceptibility to FSGS cannot be excluded. ACTN4 mutations seem to account for approximately 4% of familial FSGS.

Use of Mycophenolate Mofetil in Autoimmune and Renal Diseases

Progress in understanding the pathogenesis and treatment of rheumatologic and glomerular diseases such as systemic lupus erythematosus and particularly lupus nephritis has been closely linked with the development of newer immunosuppressive agents. With improved patient survival following the institution of cyclophosphamide and corticosteroid therapy, longer-term management issues came to the forefront, especially how to decrease adverse effects of the immunosuppressive regimen. Many of the immunosuppressive regimens used in lupus patients were first established as efficacious and safe through their use in solid organ transplantation. Mycophenolate mofetil (MMF) is now widely used in the field of transplantation. Following anecdotal reports describing benefits of MMF in lupus and lupus nephritis patients, small studies and finally large randomized, controlled trials have established the use of MMF in these patients, particularly those with lupus nephritis. MMF use in other rheumatologic and renal diseases has been evaluated in only smaller studies and very few randomized controlled trials. Nevertheless, many studies currently are ongoing with this immunosuppressive agent. This article will review the published data and the experience of two major New York medical centers with the use of MMF in autoimmune and renal diseases.

Membranoproliferative glomerulonephritis type II (dense deposit disease): an update

Membranoproliferative glomerulonephritis type II (MPGN II) is a rare disease characterized by the deposition of abnormal electron-dense material within the glomerular basement membrane of the kidney and often within Bruch's membrane in the eye. The diagnosis is made in most patients between the ages of 5 and 15 yr, and within 10 yr, approximately half progress to end-stage renal disease, occasionally with the late comorbidity of visual impairment. The pathophysiologic basis of MPGN II is associated with the uncontrolled systemic activation of the alternative pathway (AP) of the complement cascade. In most patients, loss of complement regulation is caused by C3 nephritic factor, an autoantibody directed against the C3 convertase of the AP, but in some patients, mutations in the factor H gene have been identified. For the latter patients, plasma replacement therapy prevents renal failure, but for the majority of patients, there is no proven effective treatment. The disease recurs in virtually all renal allografts, and a high percentage of these ultimately fail. The development of molecular diagnostic tools and new therapies directed at controlling the AP of the complement cascade either locally in the kidney or at the systemic level may lead to effective treatments for MPGN II.

Proliferative glomerulonephritis with monoclonal IgG deposits: a distinct entity mimicking immune-complex glomerulonephritis

BACKGROUND

Renal disease related to the deposition of monoclonal immunoglobulins containing both heavy and light chains can occur in type 1 cryoglobulinemia, Randall type light and heavy chain deposition disease (LHCDD), and immunotactoid glomerulonephritis. We report a novel phenotype of glomerular injury that does not conform to any of the previously described patterns of glomerular involvement by monoclonal gammopathy.

METHODS

Ten cases of unclassifiable proliferative glomerulonephritis manifesting glomerular monoclonal immunoglobulin G (IgG) deposits were identified retrospectively from the archives of the Renal Pathology Laboratory of Columbia University over the past 3 years (biopsy incidence 0.21%).

RESULTS

The monoclonal immunoglobulins formed granular electron dense deposits in mesangial, subendothelial, and subepithelial sites, mimicking ordinary immune complex-mediated glomerulonephritis and producing a diffuse endocapillary proliferative or membranoproliferative glomerulonephritis. However, by immunofluorescence, the deposits were monoclonal, staining for a single light chain isotype and a single gamma subclass (including two IgG1kappa, one IgG1lambda, one IgG2lambda, four IgG3kappa, and one IgG3lambda). All cases stained for the three constant domains of the gamma heavy chain (CH1, CH2, and CH3), suggesting deposition of a nondeleted immunoglobulin molecule. Tissue fixation of complement was observed in 90% of cases, and 40% of patients had hypocomplementemia. Clinical presentations included renal insufficiency in 80% (mean serum creatinine 2.8 mg/dL, range 0.9 to 8.0), proteinuria in 100% (mean urine protein 5.8 g/day; range 1.9 to 13.0), nephrotic syndrome in 44%, and microhematuria in 60%. A monoclonal serum protein with the same heavy and light chain isotype as that of the glomerular deposits was identified in 50% of cases (including three IgGkappa and two IgGlambda); however, no patient had clinical or laboratory features of type 1 cryoglobulinemia. No patient had overt myeloma or lymphoma at presentation or over the course of follow-up (mean 12 months).

CONCLUSION

Glomerular deposition of monoclonal IgG can produce a proliferative glomerulonephritis that mimics immune-complex glomerulonephritis by light and electron microscopy. Proper recognition of this entity requires confirmation of monoclonality by staining for the gamma heavy chain subclasses.

The classification of glomerulonephritis in systemic lupus erythematosus revisited

The currently used classification reflects our understanding of the pathogenesis of the various forms of lupus nephritis, but clinicopathologic studies have revealed the need for improved categorization and terminology. Based on the 1982 classification published under the auspices of the World Health Organization (WHO) and subsequent clinicopathologic data, we propose that class I and II be used for purely mesangial involvement (I, mesangial immune deposits without mesangial hypercellularity; II, mesangial immune deposits with mesangial hypercellularity); class III for focal glomerulonephritis (involving <50% of total number of glomeruli) with subdivisions for active and sclerotic lesions; class IV for diffuse glomerulonephritis (involving > or = 50% of total number of glomeruli) either with segmental (class IV-S) or global (class IV-G) involvement, and also with subdivisions for active and sclerotic lesions; class V for membranous lupus nephritis; and class VI for advanced sclerosing lesions]. Combinations of membranous and proliferative glomerulonephritis (i.e., class III and V or class IV and V) should be reported individually in the diagnostic line. The diagnosis should also include entries for any concomitant vascular or tubulointerstitial lesions. One of the main advantages of the current revised classification is that it provides a clear and unequivocal description of the various lesions and classes of lupus nephritis, allowing a better standardization and lending a basis for further clinicopathologic studies. We hope that this revision, which evolved under the auspices of the International Society of Nephrology and the Renal Pathology Society, will contribute to further advancement of the WHO classification.

The classification of glomerulonephritis in systemic lupus erythematosus revisited

The currently used classification reflects our understanding of the pathogenesis of the various forms of lupus nephritis, but clinicopathologic studies have revealed the need for improved categorization and terminology. Based on the 1982 classification published under the auspices of the World Health Organization (WHO) and subsequent clinicopathologic data, we propose that class I and II be used for purely mesangial involvement (I, mesangial immune deposits without mesangial hypercellularity; II, mesangial immune deposits with mesangial hypercellularity); class III for focal glomerulonephritis (involving <50% of total number of glomeruli) with subdivisions for active and sclerotic lesions; class IV for diffuse glomerulonephritis (involving > or =50% of total number of glomeruli) either with segmental (class IV-S) or global (class IV-G) involvement, and also with subdivisions for active and sclerotic lesions; class V for membranous lupus nephritis; and class VI for advanced sclerosing lesions. Combinations of membranous and proliferative glomerulonephritis (i.e., class III and V or class IV and V) should be reported individually in the diagnostic line. The diagnosis should also include entries for any concomitant vascular or tubulointerstitial lesions. One of the main advantages of the current revised classification is that it provides a clear and unequivocal description of the various lesions and classes of lupus nephritis, allowing a better standardization and lending a basis for further clinicopathologic studies. We hope that this revision, which evolved under the auspices of the International Society of Nephrology and the Renal Pathology Society, will contribute to further advancement of the WHO classification.

Randomized trial of an inhibitor of formation of advanced glycation end products in diabetic nephropathy

BACKGROUND/AIMS

Pimagedine inhibits the formation of advanced glycation end products and slows the progression of diabetic complications in experimental models. This study was undertaken to determine if pimagedine ameliorates nephropathy in type 1 (insulin-dependent) diabetes mellitus.

METHODS

This was a randomized, double-masked, placebo-controlled study performed in 690 patients with type 1 diabetes mellitus, nephropathy, and retinopathy. The patients received twice daily dosing with placebo, pimagedine 150 mg, or pimagedine 300 mg for 2-4 years. The primary end point was the time to doubling of serum creatinine; the secondary end points included evaluations of proteinuria, kidney function, and retinopathy.

RESULTS

Serum creatinine doubled in 26% (61/236) of the placebo-treated patients and in 20% (91/454) of those who received pimagedine (p = 0.099). The estimated glomerular filtration rate decreased more slowly in the pimagedine-treated patients with a 36-month decrease from baseline of 6.26 ml/min/1.73 m(2) as compared with 9.80 ml/min/1.73 m(2) in the placebo-treated patients (p = 0.05), and pimagedine reduced the 24-hour total urinary proteinuria. (The mean reduction from baseline at month 36 was 732 mg/24 h at the low dose and 329 mg/24 h at the high dose as compared with 35 mg/24 h in the placebo group; p </= 0.001.) Fewer pimagedine-treated patients with baseline and end point evaluations (31/324; 10%) as compared with those receiving placebo (16%; 28/179) experienced a three-step or greater progression of the retinopathy (Early Treatment of Diabetic Retinopathy Study) score (p = 0.030). Three patients receiving high-dose pimagedine but none receiving low-dose treatment developed glomerulonephritis.

CONCLUSIONS

While this study did not demonstrate a statistically significant beneficial effect of pimagedine on the progression of overt nephropathy resulting from type 1 diabetes, it is noteworthy in providing the first clinical proof of the concept that inhibiting advanced glycation end product formation can result in a clinically important attenuation of the serious complications of type 1 diabetes mellitus.

Prognosis in proliferative lupus nephritis: the role of socio-economic status and race/ethnicity

BACKGROUND

Studies of proliferative lupus nephritis (PLN) suggest that African-Americans have a poorer prognosis than Whites. However, no study has simultaneously examined socio-economic status. We studied rates of progression of PLN among a tri-ethnic population with respect to socio-economic status and race/ethnicity.

METHODS

A retrospective cohort study was carried out using individual and census-based neighbourhood data. Consecutive patients in urban tertiary care centres with biopsy-proven PLN were studied. The main outcome was time to doubling of serum creatinine.

RESULTS

Among 128 patients with PLN, the percentage of patients who did not double their serum creatinine at 5 years was 67.0% (+/-4.8%) and at 10 years was 58.9% (+/-5.7%). In bivariate analyses, residence in a poor neighbourhood was positively associated with progression (P = 0.03), as was African-American and Hispanic race/ethnicity (P = 0.01). Residence in a poor neighbourhood remained associated with progression of disease after adjustment for age, sex, creatinine, hypertension, cyclophosphamide treatment and race/ethnicity [relative risk (RR) 3.5, 95% confidence interval (CI) 1.2-11, P = 0.03]. After adjustment for poverty and insurance, the RR for African-American race/ethnicity was reduced from 3.5 to 2.7 and was not statistically associated with progression of disease in the full model (P = 0.10). A similar reduction in RR from 5.5 to 3.6 was seen for Hispanic race/ethnicity, but this retained statistical significance (P = 0.03).

CONCLUSIONS

Poverty is an important risk factor for progression of PLN, independent of race/ethnicity. Hispanics have an elevated risk similar to or greater than African-Americans. Given these findings, some of the poorer prognosis of African-American patients with PLN may result from socio-economic rather than biological or genetic factors.

Hyperlipidemia and thrombotic complications in patients with membranous nephropathy

Membranous nephropathy (MN), the most common cause of adult-onset nephrotic syndrome (NS) in Caucasians, is associated commonly with the secondary complications of hyperlipidemia and hypercoagulability. These may increase the risk for cardiovascular disease, alter the rate of progression of renal disease, and raise the risk for thromboembolic events. The treatment of these secondary effects remains controversial. Although no clear practice guidelines are available to assist the clinician in deciding how and when to start disease-modifying therapies, the literature provides enough information to make reasonable decisions in most clinical scenarios. Prospective trials in the future will provide definitive information on how to best treat these abnormalities.

Analysis of metabolic parameters as predictors of risk in the RENAAL study

OBJECTIVE

Metabolic factors such as glycemic control, hyperlipidemia, and hyperkalemia are important considerations in the treatment of patients with type 2 diabetes and nephropathy. In the RENAAL (Reduction of End Points in Type 2 Diabetes With the Angiotensin II Antagonist Losartan) study, losartan reduced renal outcomes in the patient population. This post hoc analysis of the RENAAL study reports the effects of losartan on selected metabolic parameters and assesses the relationship between baseline values of metabolic parameters and the primary composite end point or end-stage renal disease (ESRD).

RESEARCH DESIGN AND METHODS

Glycemic control (HbA(1c)) and serum lipid, uric acid, and potassium levels were compared between the losartan and placebo groups over time, and baseline levels were correlated with the risk of reaching the primary composite end point (doubling of serum creatinine, ESRD, or death) or ESRD alone.

RESULTS

Losartan did not adversely affect glycemic control or serum lipid levels. Losartan-treated patients had lower total (227.4 vs. 195.4 mg/dl) and LDL (142.2 vs. 111.7 mg/dl) cholesterol. Losartan was associated with a mean increase of up to 0.3 mEq/l in serum potassium levels; however, the rate of hyperkalemia-related discontinuation was similar between the placebo and losartan groups. Univariate analysis revealed that baseline total and LDL cholesterol and triglyceride levels were associated with increased risk of developing the primary composite end point. Similarly, total and LDL cholesterol were also associated with increased risk of developing ESRD.

CONCLUSIONS

Overall, losartan was well tolerated by patients with type 2 diabetes and nephropathy and was associated with a favorable effect on the metabolic profile of this population.

Fibrillary and immunotactoid glomerulonephritis: Distinct entities with different clinical and pathologic features

BACKGROUND

Controversy surrounds the relatedness of fibrillary glomerulonephritis (FGN) and immunotactoid glomerulonephritis (IT).

METHODS

To better define their clinicopathologic features and outcome, we report the largest single center series of 67 cases biopsied from 1980 to 2001, including 61 FGN and 6 IT. FGN was defined by glomerular immune deposition of Congo red-negative randomly oriented fibrils of < 30 nm (mean, 20.1 +/- 0.4 nm). IT was defined by glomerular deposition of hollow, stacked microtubules of > or = 30 nm (mean, 38.2 +/- 5.7 nm).

RESULTS

FGN comprised 0.6% of total native kidney biopsies and IT was tenfold more rare (0.06%). Deposits in FGN were immunoglobulin G (IgG) dominant and polyclonal in 96%. IgG subtype analysis in 19 FGN cases showed monotypic deposits in four (two IgG1 and two IgG4) and oligotypic deposits in 15 (all combined IgG1 and IgG4). In IT, deposits were IgG dominant in 83% and monoclonal in 67% (three IgG1 kappa and one IgG1 lambda). FGN patients were a mean age of 57 years, 92% were Caucasian, and 39% were male. At biopsy, FGN patients had the following clinical characteristics (mean, range): creatinine 3.1 mg/dL (0.5 to 14), proteinuria 6.5 g/day (0.8 to 25), 60% microhematuria, and 59% hypertension. Histologic patterns of FGN were diverse, including diffuse proliferative glomerulonephritis (DPGN) (nine cases), membranoproliferative glomerulonephritis (MPGN) (27 cases), mesangial proliferative/sclerosing (MES) (13), membranous glomerulonephritis (MGN) (four), and diffuse sclerosing (DS) (eight). The more proliferative (MPGN and DPGN) and sclerosing (DS) forms presented with a higher creatinine and greater proteinuria compared to MES and MGN. Median time to end-stage renal disease (ESRD) was 24.4 months for FGN and mean time to ESRD varied by histologic subtype: DS 7 months, DPGN 20 months, MPGN 44 months, compared to MES 80 months and MGN 87 months. There was no statistically significant effect of immunosuppressive therapy (given to 36% of FGN patients). By Cox regression (hazard ratio, confidence interval, P value), independent predictors of progression to ESRD were creatinine at biopsy [2.05 (1.55 to 2.72) P < 0.001] and severity of interstitial fibrosis [2.01 (1.05 to 3.85) P = 0.034]. Although IT had similar presentation, histologic patterns, and outcome compared to FGN, it had a greater association with monoclonal gammopathy (P = 0.014), underlying lymphoproliferative disease (P = 0.020), and hypocomplementemia (P = 0.032).

CONCLUSION

FGN is an idiopathic condition characterized by polyclonal immune deposits with restricted gamma isotypes. Most patients present with significant renal insufficiency and have a poor outcome despite immunosuppressive therapy, and outcome correlates with histologic subtype. By contrast, IT often contains monoclonal IgG deposits and has a significant association with underlying dysproteinemia and hypocomplementemia. Differentiation of FGN from the much more rare entity IT appears justified on immunopathologic, ultrastructural, and clinical grounds.

Collapsing glomerulopathy

Collapsing glomerulopathy is a morphologic variant of focal segmental glomerulosclerosis (FSGS) characterized by segmental and global collapse of the glomerular capillaries, marked hypertrophy and hyperplasia of podocytes, and severe tubulointerstitial disease. The cause of this disorder is unknown, but nearly identical pathologic findings are present in idiopathic collapsing glomerulopathy and human immunodeficiency virus (HIV)-associated nephropathy, and collapsing glomerulopathy has been associated with parvovirus B19 infection and treatment with pamidronate. The pathogenesis of collapsing glomerulopathy involves visceral epithelial cell injury leading to cell cycle dysregulation and a proliferative phenotype. Clinically, collapsing glomerulopathy is characterized by black racial predominance, a high incidence of nephrotic syndrome, and rapidly progressive renal failure. Collapsing glomerulopathy also may recur after renal transplantation or present de novo, often leading to loss of the allograft. The optimal treatment for collapsing glomerulopathy is unknown. Treatments may include steroids or cyclosporine in addition to aggressive blood pressure control, angiotensin converting enzyme inhibitors and/or angiotensin II receptor blockers, and lipid lowering agents. The role of other immunosuppressive agents such as mycophenolate mofetil in the treatment of collapsing FSGS remains to be defined. Prospective clinical trials are needed to define optimal therapy of this aggressive form of FSGS.

Membranous glomerulopathy and acute interstitial nephritis following treatment with celecoxib

Both membranous glomerulopathy and acute interstitial nephritis have been reported to occur following treatment with non-steroidal anti-inflammatory drugs. We report the first cases of membranous glomerulopathy and acute interstitial nephritis following treatment with celecoxib (Celebrex), a selective COX-2 inhibitor. The rapid and complete resolution of both conditions following discontinuation of Celebrex strongly implicates this agent in disease pathogenesis. These cases enlarge the spectrum of potential renal toxicities of the COX-2-specific non-steroidal anti-inflammatory drugs.

NPHS2 mutations in late-onset focal segmental glomerulosclerosis: R229Q is a common disease-associated allele

Mutations in NPHS2, encoding podocin, have been identified in childhood onset focal and segmental glomerulosclerosis (FSGS). The role of NPHS2 in adult disease is less well defined. We studied 30 families with FSGS and apparent autosomal recessive inheritance and 91 individuals with primary FSGS. We screened family members for NPHS2 mutations. NPHS2 mutations appeared to be responsible for disease in nine of these families. In six families, the affected individuals were compound heterozygotes for a nonconservative R229Q amino acid substitution. This R229Q variant has an allele frequency of 3.6% in a control population. In these families, R229Q was the only mutation identified on one of the two disease-associated NPHS2 alleles. We used in vitro-translated podocin and purified nephrin to investigate the effect of R229Q on their interaction and found decreased nephrin binding to the R229Q podocin. These data suggest that this common polymorphism contributes to the development of FSGS. Chromosomes bearing the R229Q mutation share a common haplotype defining an approximately 0.2-Mb region. R229Q appears to enhance susceptibility to FSGS in association with a second mutant NPHS2 allele. Identification of R229Q mutations may be of clinical importance, as NPHS2-associated disease appears to define a subgroup of FSGS patients unresponsive to corticosteroids.

Fludarabine treatment of cryoglobulinemic glomerulonephritis

Three patients (one hepatitis C positive) presented with renal insufficiency and nephrotic-range proteinuria resulting from mixed cryoglobulinemia and glomerulonephritis. All three patients received two to four cycles of intravenous fludarabine (each cycle consisted of 25 to 50 mg/d for 4 to 5 days). All patients responded to therapy with a decrease in proteinuria, increase in serum albumin, and decrease in serum creatinine. This response was evident by 2 months and persisted for 2 to 5 years. In two patients, this response was accompanied by disappearance of cryoglobulins, at least transiently. One patient developed tuberculosis with neutropenia. Transient blindness and neutropenia were seen in another patient. These results suggest that fludarabine may be a useful treatment in cryoglobulinemia with glomerulonephritis, although its use may be accompanied by side effects.

Minimal change disease in systemic lupus erythematosus

We report the clinical and pathologic findings in 7 patients with systemic lupus erythematosus and minimal change disease. All 7 patients presented with full nephrotic syndrome including peripheral edema, nephrotic range proteinuria (mean 9.6 g/day), and hypoalbuminemia (mean 1.8 g/dl). In all cases, renal biopsy revealed diffuse foot process effacement in the absence of significant peripheral capillary wall immune deposits, findings consistent with minimal-change disease. In addition, 5 cases displayed mesangial electron-dense deposits, with or without associated mesangial proliferation, consistent with underlying lupus nephritis class II. In all cases, steroid therapy induced a rapid remission of nephrotic syndrome. Minimal change disease is an underrecognized and readily reversible form of nephrotic syndrome in systemic lupus erythematosus. Because it may occur superimposed on mild mesangial proliferative lupus nephritis, this entity may be misinterpreted as an atypical presentation of lupus nephritis class II. Proper recognition of this entity requires careful integration of the renal biopsy immunofluorescence and electron microscopic findings.