sirolimus and Nephrosis

Until 1985, glucocorticoids and cytotoxic drugs were the only treatments available for idiopathic nephrotic syndrome (nephrosis), that is, minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). Trials of cyclosporine (CsA) treatment of nephrosis, the rationale of which was based on pathophysiologic considerations, have shown that this immunophillin modulator is effective in inducing and maintaining remission in patients suffering from idiopathic nephrotic syndrome. It appears that the best results, in the order of 80% remission rate, are obtained in steroid-sensitive cases, essentially MCD, and that in steroid-resistant FSGS the drug obtains remission in no more than 20% of the cases. Addition of glucocorticoids increases the success rate to approximately 30% of cases. Renal toxicity is proportional to previous impairment of renal function, primary renal disease (FSGS vs MCD) dosage >5.5 mg/kg/day and duration of treatment. The better bioavailability of the new formulation of CsA (Neoral), implies that the former dosage recommendations be reconsidered for distinctly lower figures. Repeat renal biopsy after 1 year of continuous CsA treatment is advisable, as stable serum creatinine levels may be falsely reassuring. CsA dependency is the rule during the first year of treatment. However, in some 25% of cases stable remission may be maintained after slow tapering off following 3-4 years of treatment. Other immunophillin modulators have been tried in the treatment of idiopathic nephrotic syndrome. Despite few preliminary reports indicating some success of tacrolimus the effects of this drug do not seem convincingly superior to CsA in terms of remission rate, toxicity and dependency. Rapamycin has not been tried in the treatment of nephrosis. Anecdotal cases of de novo FSGS induced by rapamycin in transplanted patients might indicate that this drug is in fact contraindicated in the treatment of nephrosis.

Topics: Cyclosporine; Humans; Immunophilins; Immunosuppressive Agents; Nephrosis; Sirolimus; Tacrolimus

Connective tissue growth factor (CTGF) is a pro-fibrotic growth factor that acts downstream of transforming growth factor (TGF)-beta. However, CTGF regulation remains unknown. We tried to determine the effect of two commonly used immunosuppressants, cyclosporine (CsA) and sirolimus (SRL), on CTGF expression in a model of chronic nephrotoxicity.. Adult Sprague-Dawley rats kept on a low-salt diet were treated daily for 4 weeks with vehicle (VH), SRL (0.3 mg/kg), CsA5 (5 mg/kg), CsA10 (10 mg/kg) or both CsA5 and SRL. CTGF and TGF-beta1 expressions were evaluated by Northern blot. Functional and histologic parameters in addition to number of apoptotic cells were determined.. At 28 days, both CsA doses were capable of inhibiting CTGF mRNA expression to levels similar to control. On the other hand, SRL increased CTGF expression by 3.5-fold. However, addition of CsA to SRL completely reversed that trend and returned levels to control. The results were different for TGF-beta1, which was increased by both CsA and SRL and to a greater extent by the drug combination.. Unlike TGF-beta, CTGF does not seem to play an important role in CsA-induced chronic nephrotoxicity. In addition, calcineurin-dependent pathways are likely involved in CTGF regulation.

Topics: Animals; Chronic Disease; Connective Tissue Growth Factor; Cyclosporine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Combinations; Gene Expression; Immediate-Early Proteins; Immunosuppressive Agents; Intercellular Signaling Peptides and Proteins; Male; Nephrosis; Rats; Rats, Sprague-Dawley; Sirolimus; Transforming Growth Factor beta1