Concanavalin A-induced suppressor cell activity in focal glomerular sclerosis

Plasmapheresis reduces proteinuria and serum capacity to injure glomeruli in patients with recurrent focal glomerulosclerosis

To test the hypothesis that a circulating mediator is associated with recurrent idiopathic focal glomerulosclerosis (FGS), we studied the effect of plasmapheresis on reducing proteinuria in patients with the disease. An in vitro assay measured the capacity of sera before and after plasmapheresis to cause increased albumin permeability (P(albumin)++) in isolated rat glomeruli. Nine patients (five males aged 2 to 66 years) who underwent plasmapheresis for recurrent FGS were identified. Study variables included age, sex, time from diagnosis of recurrence to first pheresis, glomerular hyalinosis, complications, outcome, and proteinuria before and after plasmapheresis. Rat glomeruli were isolated in medium containing 4 g/dL bovine serum albumin, and P(albumin) was determined from the change in glomerular volume in response to an albumin gradient after incubation of the glomeruli in a 1:50 dilution of patient serum. Plasmapheresis reduced proteinuria from a mean of 12 +/- 7.46 g/24 hr to 5.1 +/- 7.39 g/24 hr (P = 0.03). Six patients in whom the diagnosis was made early in the course of the disease and in whom plasmapheresis was initiated immediately had lasting remissions. Preplasmapheresis biopsies in the patients who did not achieve remissions showed both epithelial foot process effacement and glomerular sclerosis. Serum samples were available from four patients for albumin testing in vitro. P(albumin)++ was reduced from a mean of 0.76 +/- 0.17 before pheresis to 0.18 +/- 0.31 after (P = 0.07). Therefore, the mechanism by which plasmapheresis reduces proteinuria in patients with recurrent FGS involves the decreased capacity of sera from these patients to injure the glomerular permeability barrier.(ABSTRACT TRUNCATED AT 250 WORDS)

Recurrent focal glomerulosclerosis: natural history and response to therapy

PURPOSE

Recurrent focal glomerulosclerosis (FGS) has been well documented since it was first reported in 1972. However, the course of the disease after transplantation and the optimal treatment regimen have not been well defined since the introduction of newer treatment modalities.

PATIENTS AND METHODS

We reviewed all the charts of patients with biospy-proven FGS who received renal transplants at our institution from January 1980 through December 1990. Case histories consistent with diagnoses other than primary FGS (such as reflux nephropathy or intravenous drug use) were eliminated from the study. During this time period, 78 allografts were received by 71 patients with FGS. Independent variables that were analyzed included sex, race, time in months between the diagnosis of FGS and end-stage disease (dialysis or transplantation), age at time of transplantation, type of dialysis, source of allograft (cadaveric or living related), haplotype matching, donor-specific transfusions, age and sex of the donor, post-transplantation acute tubular necrosis, rejection episodes, immunosuppression regimen, use of plasmapheresis and angiotensin converting enzyme (ACE) inhibitors, and outcome.

RESULTS

FGS recurred in 25 allografts (32%) of 21 patients. Biopsy-proven diagnosis of recurrence was made a mean of 7.5 months (range: 0.5 to 44 months) after transplantation. Patients who had rapid progression to end-stage disease tended to experience more frequent recurrences. Of seven patients who received a second transplant, five patients lost the first graft to recurrent FGS, and four of those patients (80%) had a recurrence in the second allograft. Recurrent disease developed in 34% of patients concurrently treated with cyclosporine and in 28% of those treated with prednisone and azathioprine alone (NS). Patients with recurrent FGS who were treated with ACE inhibitors benefited from a significant reduction of proteinuria. Six patients underwent plasmapheresis after diagnosis of the recurrence. Three of five patients in whom the diagnosis was made early in the course of the disease and in whom plasmapheresis was initiated immediately had reversal of epithelial foot process effacement and remission of proteinuria. End-stage disease eventually developed in 14 allografts (56%) an average of 23.7 months (range: 1 to 65 months) after diagnosis of recurrent disease. The cause of failure was chronic rejection in four allografts and recurrent disease in the remaining 10 allografts.

CONCLUSIONS

FGS recurs in approximately 30% of allografts and causes graft loss in half of these. Patients who have lost a first allograft to recurrent FGS are at high risk for developing recurrent disease in a second allograft. Prolonged allograft survival is possible in patients with recurrent FGS and may best be obtained with a combination of treatment modalities including cyclosporine (perhaps in higher dosages than are routinely used in clinical renal transplantation), ACE inhibitors, and early use of plasmapheresis. The efficacy of these modalities supports the notion that recurrent FGS is caused by a circulating humoral mediator.

Therapy of focal segmental glomerulosclerosis with cyclosporine A

Six patients with biopsy-documented focal segmental glomerulosclerosis were treated with cyclosporine A (CyA) a new and potent T-cell suppressant. Dosage was adjusted to maintain trough levels between 100 and 300 ng/ml (whole blood radioimmunoassay). Patients were treated for 6 weeks or until unacceptable drug toxicity occurred. In one patient proteinuria was significantly reduced. This same individual was the only patient treated within 6 months of diagnosis. Therapy was discontinued in two patients at week 4, one because of worsening renal failure and one because of hypertension. These complications occurred despite trough CyA blood levels of less than 300 ng/ml. The results suggest that further and controlled studies of CyA are warranted in the therapy of nephrotic syndrome associated with focal segmental glomerulosclerosis, especially when used early in the course of disease. The data also suggest enhanced toxicity of CyA in patients with active nephrotic syndrome.