sirolimus and Sclerosis

Chronic allograft nephropathy (CAN) is characterized by deposition of extracellular matrix (ECM) in all renal compartments. PAI-1 seems to play a pivotal role in ECM turnover in CAN. Rapamycin has been shown to improve long-term graft survival in patients with CAN. The aim of the study was to evaluate the molecular mechanisms underlying the beneficial effects of rapamycin on CAN progression at glomerular and tubulointerstitial level.. After a biopsy-proven CAN diagnosis (T0), 18 patients on calcineurin inhibitors (CNI) were randomly assigned in a 2:1 ratio to continue CNI (6 patients) or to receive rapamycin (RAPA; 12 patients). After 2 years of treatment (T24), all patients underwent a second renal biopsy. Morphometric analysis was conducted at T0 and at T24. PAI-1 expression was evaluated at T0 and T24 by immunohistochemistry. We evaluated the effect of rapamycin on PAI-1 gene expression in cultured proximal tubular cells incubated with CD40L or thrombin, two potential CAN pathogenic mediators.. The RAPA group showed a significant regression of glomerulosclerotic lesions and only a 26% increase in interstitial fibrosis after 2 years compared to baseline, whereas the CNI group showed progression of glomerulosclerosis and 112% increase in fibrosis. Glomerular and tubulointerstitial PAI-1 expression was reduced compared to the baseline in the RAPA group, while they were unchanged in the CNI group. In vitro data showed that rapamycin significantly reduced PAI-1 gene expression induced by both CD40L and thrombin in proximal tubular epithelial cells.. These data suggest that rapamycin may modulate ECM deposition in CAN reducing PAI-1 expression.

Topics: Adult; Biopsy; CD40 Ligand; Cell Line; Cells, Cultured; Disease Progression; Fibrosis; Humans; Immunosuppressive Agents; Kidney Diseases; Kidney Glomerulus; Kidney Transplantation; Kidney Tubules; Middle Aged; Plasminogen Activator Inhibitor 1; Sclerosis; Sirolimus; Thrombin; Transplantation, Homologous

Anti-Thy1.1 transgenic mice develop glomerular lesions that mimic collapsing focal segmental glomerulosclerosis (FSGS) in humans with collapse of the glomerular tuft and marked hyperplasia of the parietal epithelial cells (PECs). Immunostaining of phosphor-S6 ribosomal protein (pS6RP) revealed high mTOR activity in PECs of the FSGS lesions of these mice. In this study we questioned whether the mTOR inhibitor rapamycin (sirolimus) could attenuate the development and progression of glomerulosclerotic lesions in the anti-Thy1.1 transgenic mice. We observed reduced mTOR signalling and proliferation in human parietal epithelial cells after rapamycin treatment. Experiments with anti-Thy1.1. mice showed that early treatment with sirolimus reduced the development of glomerular lesions and glomerular cell proliferation at day 4. Levels of albuminuria, podocyte injury and podocyte number were similar in the sirolimus and vehicle treated groups. The initial beneficial effects of sirolimus treatment were not observed at day 7. Late sirolimus treatment did not reduce albuminuria or the progression of glomerulosclerosis. Taken together, rapamycin attenuated PEC proliferation and the formation of early FSGS lesions in experimental FSGS and reduced human PEC proliferation in vitro. However, the initial inhibition of PEC proliferation did not translate into a decline of albuminuria nor in a sustained reduction in sclerotic lesions.

Topics: Albuminuria; Animals; Cell Proliferation; Glomerulosclerosis, Focal Segmental; Humans; Immunosuppressive Agents; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Sclerosis; Signal Transduction; Sirolimus; Thy-1 Antigens; TOR Serine-Threonine Kinases

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either TSC1 or TSC2. TSC has high frequency of osseous manifestations such as sclerotic lesions in the craniofacial region. However, an animal model that replicates TSC craniofacial bone lesions has not yet been described. The roles of Tsc1 and the sequelae of Tsc1 dysfunction in bone are unknown. In this study, we generated a mouse model of TSC with a deletion of Tsc1 in neural crest-derived (NCD) cells that recapitulated the sclerotic craniofacial bone lesions in TSC. Analysis of this mouse model demonstrated that TSC1 deletion led to enhanced mTORC1 signaling in NCD bones and the increase in bone formation is responsible for the aberrantly increased bone mass. Lineage mapping revealed that TSC1 deficient NCD cells overpopulated the NCD bones. Mechanistically, hyperproliferation of osteoprogenitors at an early postnatal stage accounts for the increased osteoblast pool. Intriguingly, early postnatal treatment with rapamycin, an mTORC1 inhibitor, can completely rescue the aberrant bone mass, but late treatment cannot. Our data suggest that enhanced mTOR signaling in NCD cells can increase bone mass through enlargement of the osteoprogenitor pool, which likely explains the sclerotic bone lesion observed in TSC patients.

Topics: Animals; Animals, Newborn; Bone and Bones; Cell Differentiation; Cell Proliferation; Craniofacial Abnormalities; Gene Deletion; Integrases; Mice, Knockout; Neural Crest; Organ Size; Organ Specificity; Osteoblasts; Osteogenesis; Phenotype; Sclerosis; Sirolimus; Tuberous Sclerosis Complex 1 Protein; Tumor Suppressor Proteins

HIV-associated nephropathy (HIVAN) is the manifestation of HIV gene expression by kidney cells in the presence of specific host factors. Recently, rapamycin (sirolimus) has been demonstrated to modulate the progression of HIVAN. We hypothesized that rapamycin would modulate the progression of HIVAN by attenuating HIV gene expression. To test our hypothesis, three weeks old Tg26 mice (n=6) were administered either vehicle or rapamycin (5 mg/kg, every other day, intraperitoneal) for eight weeks. At the end of the experimental period, the kidneys were harvested. In in vitro studies, human podocytes were transduced with either HIV-1 (NL4-3) or empty vector (EV), followed by treatment with either vehicle or rapamycin. Total RNA and proteins were extracted from renal tissues/cellular lysates and HIV gene transcription/translation was measured by real time PCR and Western blotting studies. Renal histological slides were graded for glomerular sclerosis and tubular dilatation with microcyst formation. Rapamycin attenuated both glomerular and tubular lesions in Tg26 mice. Rapamycin decreased transcription of HIV genes both in renal tissues as well as in HIV-1 transduced podocytes. Our data strongly indicate that HIV-1 long terminal repeat-mediated transcriptional activity was targeted by rapamycin. Rapamycin enhanced podocyte NF-κB and CREB activities but then it decreased AP-1 binding activity. Since expression of HIV genes by kidney cells has been demonstrated to be the key factor in the development HIVAN, it appears that rapamycin-induced altered transcription of HIV genes might have partly contributed to its disease modulating effects.

Topics: AIDS-Associated Nephropathy; Animals; Cell Proliferation; Cells, Cultured; Cyclic AMP Response Element-Binding Protein; Disease Models, Animal; Disease Progression; HIV-1; Humans; Kidney; Kidney Glomerulus; Kidney Tubules; Mice; NF-kappa B; Podocytes; Sclerosis; Sirolimus; Transcription Factor AP-1; Transcription, Genetic

The most serious complication of peritoneal dialysis is encapsulating peritoneal sclerosis (EPS). The prolonged inflammatory stimuli, fibrogenic cytokine overexpression, and angiogenesis that underlie EPS ultimately result in increased production of fibrous tissue, encapsulating the bowel loops. In recent years, inhibitors of mammalian target of rapamycin (mTOR) as an alternative agent for calcineurin inhibitor toxicity have been widely used in organ transplantation. These agents have also been used since the 1990s in endovascular medicine for drug-eluting stents because of antiproliferative effects on vascular smooth muscle cells and potent anti-inflammatory properties by direct action on human immune cells. Because of the shared characteristics of EPS and other fibrotic processes, we hypothesized that everolimus, an mTOR inhibitor can reverse the process responsible for the eventual development of EPS. We allocated 32 non-uremic albino Wistar rats to 4 groups: control group, 2 mL isotonic saline injected intraperitoneally (IP) daily for 3 weeks; CG group, 2 mL/200 g (0.1%) chlorhexidine gluconate (CG) injected IP daily and ethanol (15%) dissolved in saline, for 3 weeks; resting group, CG (weeks 0 - 3), plus peritoneal rest (weeks 3 - 6); and Evo-R, CG (weeks 0 - 3), plus 0.3 mg/L everolimus in drinking water (weeks 3 - 6). At the end of the study, we performed a 1-hour peritoneal equilibration test with 25 mL 3.86% PD solution, and examined the dialysate-to-plasma ratio of urea (D/P urea), dialysate white blood cell count, ultrafiltration (UF) volume, and morphologic change in the parietal peritoneum. Exposure to CG for 3 weeks resulted in alterations in peritoneal transport (increased D/P urea, decreased UF volume, p < 0.05) and morphology (increased inflammation, neovascularization, fibrosis, and peritoneal thickness, p < 0.05). Peritoneal rest has some beneficial effect only on UF failure and dialysate cell count (p < 0.05). However; everolimus was more effective than peritoneal rest with regard to vascularity and peritoneal thickness (p < 0.05). Everolimus has beneficial effects on UF failure, inflammation, and fibrosis. Everolimus may have therapeutic value in the management of EPS.

Topics: Animals; Cell Proliferation; Everolimus; Female; Immunosuppressive Agents; Injections, Intraperitoneal; Peritoneal Dialysis; Peritoneal Diseases; Peritoneum; Protein Kinases; Rats; Rats, Wistar; Sclerosis; Sirolimus; TOR Serine-Threonine Kinases

Cortical tubers are epileptogenic lesions in patients with tuberous sclerosis complex (TSC). Giant cells and dysplastic neurons are pathological hallmarks of cortical tubers. Severe astrogliosis, which is invariably present in tubers, has attracted much less attention. We hypothesize that the development of astrogliosis in cortical tubers constitutes a primary pathology of astrocytes and is directly related to TSC 1/2 mutations.. To begin to test this hypothesis, we performed immunohistochemical and electron microscopic analysis of brain tuber tissue resected from epileptic TSC patients. We compared alterations in tuber astrocytes to those found in other acute and chronic human epilepsy pathologies.. We found that astrogliosis in tubers is comprised of a mixture of "gliotic" and "reactive" astrocytes. The majority of tuber astrocytes are "gliotic" astrocytes that are morphologically and immunophenotypically similar to astrocytes in areas of gliosis in hippocampal sclerosis (HS). However, specific immunostaining features differentiate TSC gliosis from HS gliosis. "Reactive" tuber astrocytes are large-sized, vimentin positive cells in the vicinity of giant cells that show activation of the mammalian target of rapamycin (mTOR) pathway, consistent with mutated TSC gene function. These cells resemble acutely reactive human astrocytes seen in tissue resected from depth electrode implantation patients. Oligodendrocytes and NG2 expressing glial cells do not have any detectable alterations within tubers.. We conclude that astrocytes are the type of glial cell selectively impacted in cortical tuber pathology. We propose that tubers may be dynamic lesions, with progression of astrocytes over time from "reactive" to "gliotic." Tuber astrogliosis in TSC may represent a genetic "model" of gliosis that is phenotypically similar to gliosis seen in acquired human pathologies.

Topics: Antigens; Astrocytes; Cerebral Cortex; Epilepsy; Giant Cells; Gliosis; Hippocampus; Humans; Immunohistochemistry; Microscopy, Electron; Models, Genetic; Mutation; Neuroglia; Phenotype; Proteoglycans; Sclerosis; Sirolimus; Tuberous Sclerosis; Vimentin

Topics: Anti-Bacterial Agents; Anti-Inflammatory Agents; Humans; Male; Middle Aged; Peritonitis; Prednisolone; Sclerosis; Sirolimus