Effectiveness and cost of replacing a calcineurin inhibitor with sirolimus to slow the course of chronic kidney disease in renal allografts

Reducing mTOR augments parietal epithelial cell density in a model of acute podocyte depletion and in aged kidneys

Parietal epithelial cell (PEC) response to glomerular injury may underlie a common pathway driving fibrogenesis following podocyte loss that typifies several glomerular disorders. Although the mammalian target of rapamycin (mTOR) pathway is important in cell homeostasis, little is known of the biological role or impact of reducing mTOR activity on PEC response following podocyte depletion, nor in the aging kidney. The purpose of these studies was to determine the impact on PECs of reducing mTOR activity following abrupt experimental depletion in podocyte number, as well as in a model of chronic podocyte loss and sclerosis associated with aging. Podocyte depletion was induced by an anti-podocyte antibody and rapamycin started at day 5 until death at day 14 Reducing mTOR did not lead to a greater reduction in podocyte density, despite greater glomerulosclerosis. However, mTOR inhibition lead to an increase in PEC density and PEC-derived crescent formation. Additionally, markers of epithelial-to-mesenchymal transition (platelet-derived growth factor receptor-β, α-smooth muscle actin, Notch-3) and PEC activation (CD44, collagen IV) were further increased by mTOR reduction. Aged mice treated with rapamycin for 1, 2, and 10 wk before death at 26.5 mo (≈75-yr-old human age) had increased the number of glomeruli with a crescentic appearance. mTOR inhibition at either a high or low level lead to changes in PEC phenotype, indicating PEC morphology is sensitive to changes mediated by global mTOR inhibition.

Combining cytochrome P-450 3A4 modulators and cyclosporine or everolimus in transplantation is successful

AIM: To describe the long term follow-up of kidney allograft recipients receiving ketoconazole with calcineurin inhibitors (CNI) alone or combined with everolimus.

METHODS: This is an open-label, prospective observational clinical trial in low immunologic risk patients who, after signing an Institutional Review Board approved consent form, were included in one of two groups. The first one (n = 59) received everolimus (target blood level, 3-8 ng/mL) and the other (n = 114) azathioprine 2 mg/kg per day or mycophenolate mofetyl (MMF) 2 g/d. Both groups also received tapering steroids, the cytochrome P-450 3A4 (CYP3A4) modulator, ketoconazole 50-100 mg/d, and cyclosporine with C0 targets in the everolimus group of 200-250 ng/mL in 1 mo, 100-125 ng/mL in 2 mo, and 50-65 ng/mL thereafter, and in the azathioprine or MMF group of 250-300 ng/mL in 1 mo, 200-250 ng/mL in 2 mo, 180-200 ng/mL until 3-6 mo, and 100-125 ng/mL thereafter. Clinical visits were performed monthly the first year and quarterly thereafter by treating physicians and all data was extracted by the investigators.

RESULTS: The clinical characteristics of these two cohorts were similar. During the follow up (66 + 31 mo), both groups showed comparable clinical courses, but the biopsy proven acute rejection rate during the full follow-up period seemed to be lower in the everolimus group (20% vs 36%; P = 0.04). The everolimus group did not show a higher surgical complication rate than the other group. By the end of the follow-up period, the everolimus group tended to show a higher glomerular filtration rate. Nevertheless, we found no evidence of a consistent negative slope of the temporal allograft function estimated by the modification of the diet in renal disease formula in any of both groups. At 6 years of follow-up, the uncensored and death-censored graft survivals were 91% and 93%, and 91% and 83% in the everolimus plus cyclosporine, and cyclosporine alone groups, respectively. The addition of ketoconazole saved 80% of cyclosporine and 56% of everolimus doses.

CONCLUSION: Combining CYP3A4 modulators with CNI or mammalian target of rapamycin inhibitor, in low immunological risk kidney transplant recipients is feasible, effective, safe and affordable even in the long term.

Recent advances in renal interstitial fibrosis and tubular atrophy after kidney transplantation

Although kidney transplantation has been an important means for the treatment of patients with end stage of renal disease, the long-term survival rate of the renal allograft remains a challenge. The cause of late renal allograft loss, once known as chronic allograft nephropathy, has been renamed “interstitial fibrosis and tubular atrophy” (IF/TA) to reflect the histologic pattern seen on biopsy. The mechanisms leading to IF/TA in the transplanted kidney include inflammation, activation of renal fibroblasts, and deposition of extracellular matrix proteins. Identifying the mediators and factors that trigger IF/TA may be useful in early diagnosis and development of novel therapeutic strategies for improving long-term renal allograft survival and patient outcomes. In this review, we highlight the recent advances in our understanding of IF/TA from three aspects: pathogenesis, diagnosis, and treatment.