Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment options in human mesangioproliferative glomerulonephritis/sclerosis, mostly IgA nephropathy, are limited. Progressive mesangioproliferative nephropathy represents a major cause of end-stage kidney disease. The present study explores the efficacy of low-dose mTOR inhibition by rapamycin in a chronic-progressive model of mesangioproliferative glomerulosclerosis (cGS). cGS was induced by high-dose anti-thy1 antibody injection into uninephrectomized rats. Rapamycin administration (2.5 mg.kg(-1).body wt(-1)) was started 10 days after antibody injection and continued until week 20. cGS was characterized by advancing proteinuria, increased blood pressure, marked tubulointerstitial and glomerular fibrosis, cell proliferation and round cell infiltration, and impaired renal function. Kruskal-Wallis and Mann-Whitney U-tests were used for statistical analysis. The course of chronic anti-thy1-induced glomerulosclerosis was significantly attenuated by low-dose rapamycin treatment. In week 20, this was demonstrated by improvements in proteinuria (-38%), systolic blood pressure (-16 mmHg), tubulointerstitial and glomerular histological matrix accumulation (-61 and -24%), transforming growth factor-beta1 overexpression (-41 and -47%), collagen I deposition (-53 and -65%), cell proliferation (-90 and -76%), and leukocyte number (macrophages -52 and -53%; lymphocytes -58 and 51%), respectively. Rapamycin improved renal function as well (blood creatinine -0.68 mg/dl, urea -66.7 mg/day, and creatinine clearance +0.13 ml.min(-1).100 g body wt(-1)). In conclusion, low-dose mTOR inhibition by rapamycin limits the progressive course of anti-thy1-induced renal disease toward chronic glomerulosclerosis, tubulointerstitial fibrosis, and renal insufficiency. Renoprotection by rapamycin involved significant beneficial effects on multiple key pathways in the progression of chronic renal disease, i.e., proteinuria, extracellular matrix accumulation, renal cell proliferation, and inflammatory cell infiltration.
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PMID:Low-dose mTOR inhibition by rapamycin attenuates progression in anti-thy1-induced chronic glomerulosclerosis of the rat. 1809 32

The nephrotic range of proteinuria is uncommon in scleroderma renal crisis. This 46-yr-old woman with a medical history of scleroderma presented with very high blood pressure, a sudden elevation of serum creatinine, and proteinuria in the nephrotic range. Renal biopsy revealed onion-skin type of arterial changes with necrosis, confirming the presence of scleroderma nephropathy. Electron microscopy showed diffuse fusion of foot processes. Immunohistochemical staining (IHC) revealed increased expression in glomeruli of phosphorylated mammalian target of rapamycin (p-mTOR). These findings suggest that fusion of foot processes and activation of mammalian target of rapamycin-dependent pathways in podocytes are most likely responsible for the severe proteinuria in this patient with scleroderma nephropathy.
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PMID:Nephrotic range proteinuria: rare manifestation of scleroderma renal crisis. 1846 63

Massive urinary protein excretion has been observed after conversion from calcineurin inhibitors to mammalian target of rapamycin (mToR) inhibitors, especially sirolimus, in renal transplant recipients with chronic allograft nephropathy. Because proteinuria is a major predictive factor of poor transplantation outcome, many studies focused on this adverse event during the past years. Whether proteinuria was due to sirolimus or only a consequence of calcineurin inhibitors withdrawal remained unsolved until high range proteinuria has been observed during sirolimus therapy in islet transplantation and in patients who received sirolimus de novo. Podocyte injury and focal segmental glomerulosclerosis have been related to mToR inhibition in some patients, but the pathways underlying these lesions remain hypothetic. We discuss herein the possible mechanisms and the significance of mToR blockade-induced proteinuria.
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PMID:mToR inhibitors-induced proteinuria: mechanisms, significance, and management. 1863 65

Sirolimus (SRL) is a recently available immunosuppressive agent. SRL, is a macrolide isolated from Streptomyces hydroscopicus that, in complex with its cellular receptor, FK binding protein, potently inhibits downstream signaling by the mammalian target of rapamycin (mTOR). It has been shown to reduce the incidence of acute rejection episode after renal transplantation. SRL by itself does not seem to cause significant nephrotoxicity in most animals and human studies in normal conditions. However, when combined with calcineurin inhibitors, serum creatinine levels often increase. The mechanisms for the synergism of this side-effect are still discussed. Furthermore, recent clinical data have shown that the administration of SRL immediately after renal transplant delay the recovery from delayed graft function. This effect may be secondary to the inhibition of the proliferation of the renal tubular cells which is a normal process for tubular repair. Some experimental data have confirmed this hypothesis. Finally, in the long-term, SRL use has been associated with a significant increase of proteinuria which may in the long-term increase the risk of graft loss of cardio-vascular morbio-mortality. For all these reasons, SRL nephrotoxicty has become an important issue after renal transplantation. The review will discuss the clinical and the experimental data regarding this complication, which has been underestimated.
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PMID:Sirolimus early graft nephrotoxicity: clinical and experimental data. 1869 Sep 29

Everolimus (EVL), an antagonist of mammalian target of rapamycin, has been recently introduced into solid organ transplantation either associated with low dose of anticalcineurins (CNI) or replacing them in an attempt to avoid nephrotoxicity and chronic allograft nephropathy. Due to the molecular similarities with sirolimus, it has been expected that there would be the same incidence of metabolic changes and adverse events. We retrospectively studied kidney allograft recipients converted from CNI to EVL during a 12-month period. Patients received a standard dose of EVL starting at 1.5 mg/d and thereafter titrating to achieve trough levels in the range of 3 to 5 ng/mL. Patients achieved mean EVL trough levels of 5.2, 4.0 and 4.5 ng/mL at 1, 6, and 12 months, respectively. One year following conversion, the calculated creatinine clearance increased from 57 to 63 mL/min and proteinuria did not change. Fasting blood glucose levels decreased significantly following conversion to EVL. During the same time, no significant changes were observed in body weight, body mass index, albumin, cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, lipid-lowering medication requirements, blood magnesium, and uric acid. We concluded that EVL did not negatively influence various nutritional parameters.
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PMID:Metabolic changes following conversion from an anticalcineurin-based therapy to an everolimus-based one: a single-center experience. 1901 Feb 49

The immunosuppressive mammalian target of rapamycin (mTOR) inhibitors can cause proteinuria, especially in kidney and heart transplanted patients. Podocytes play a major role in establishing the selective permeability of the blood-urine filtration barrier. Damage of these cells leads to proteinuria, a hallmark of most glomerular diseases. Interestingly, podocyte damage and focal segmental glomerulosclerosis can occur after treatment with an mTOR inhibitor in some transplant patients. To investigate the mechanisms of mTOR inhibitor-induced podocyte damage, we analyzed the effect of rapamycin on mTOR signaling and cellular function in human podocytes. We found that prolonged rapamycin treatment reduced the expression of total mTOR, which correlates with diminished levels of mTOR phosphorylation at Ser(2448) and Ser(2481). In addition, treatment with rapamycin reduced rictor expression and mTORC2 formation, resulting in a reduced phosphorylation of protein kinase B at Ser(473). The expression level of the slit-diaphragm proteins nephrin and transient receptor potential cation channel 6 as well as the cytoskeletal adaptor protein Nck significantly decreased. Moreover, rapamycin reduced cell adhesion and cell motility, which was accompanied by an enhanced formation of dot-like actin-rich structures. Our data provide new molecular insights explaining which pathways and molecules are affected in podocytes by an imbalanced mTOR function because of rapamycin treatment.
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PMID:mTOR regulates expression of slit diaphragm proteins and cytoskeleton structure in podocytes. 1901 20

Sirolimus (SRL) is a non-nephrotoxic immunosuppressive drug blocking T-cell proliferation through mTOR inhibition. SRL can be used as (1) an early drug in a calcineurin inhibitor-free protocol in the first 3 months after transplantation, (2) in the early and late conversion protocols as suggested by the multicenter randomized CONVERT trial, and (3) in recipients from marginal donors, because calcineurin inhibitors can increase the preexisting renal damage induced by age, hypertension, and diabetes that are frequent in elderly cadaveric donors. In any case, SRL should be used in patients with a cutoff of proteinuria (<or=800 mg/24 hr) or proteinuria-to-creatinine ratio less than 0.11.
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PMID:Review of symposium. Sirolimus in kidney transplantation. 1938 85

Several novel therapies have been approved recently in advanced renal cell carcinoma (RCC). These agents inhibit pathways downstream of loss of the von Hippel-Lindau gene VHL. They target the vascular endothelial growth factor (VEGF) ligand, VEGF receptor (VEGFR), mammalian target of rapamycin (mTOR), and other potentially important pathways. Even with improvements in survival, disease progresses in all patients. There is a critical need to increase complete responses (now rare). One such strategy is combining several agents to block different levels of the VEGF-VEGFR axis (vertical blockade). Alternatively, combination of a VEGF-VEGFR inhibitor with an mTOR inhibitor is attractive. Finally, horizontal blockade of VEGFR with epidermal growth factor receptor and/or platelet-derived growth factor receptor, all signaling pathways activated by hypoxia-inducible factor, is another approach. Already trials have revealed difficulties with combination therapy. By combining agents, the toxicity of 1 or both can be enhanced. The authors of this article report their experience with sorafenib plus bevacizumab, which produced increases in hand-foot syndrome, hypertension, and proteinuria, all known toxic effects. Clinical activity was impressive with 25 responses in 48 patients (52% response rate). Other combinations also required dose reductions (sorafenib with temsirolimus) or were intolerable (sunitinib with temsirolimus or sunitinib with bevacizumab). Unexpected toxicity characterized by microangiopathic hemolytic anemia occurred late in treatment with sunitinib and bevacizumab. Toxicity may be more severe in patients with RCC, who frequently have 1 kidney and poor renal function. Once tolerability for combination regimens has been established, it will be critical to design informative phase 2 trials and address the benefit of combination versus sequential therapy.
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PMID:Combination targeted therapy in advanced renal cell carcinoma. 1940 58

Anti-mTOR may induce proteinuria when utilized after renal transplantation. Little is known about the pathogenesis and composition of proteinuria. To clarify this unresolved aspect, we analyzed urinary protein composition utilizing an integrated proteomics approach, including quantitative assays, 2-dimensional electrophoresis, MALDI-TOF, and Western blots among 48 renal transplant recipients treated with everolimus (EVL; n = 31) or enteric-coated mycophenolic acid (EC-MPA; n = 17). High (>3 g/d) or intermediate levels of proteinuria (1-3 g) developed in 12 EVL patients (39%) compared with 4 subjects (23%) in the EC-MPA group. Proteinuria, which started during the first 2 days after EVL, tended to reduce during the follow-up. Quantitative proteomics showed an increase in low molecular proteins beta2 microglobulin (P < .001) and alpha1 microglobulin (P < .025). Qualitative proteomics showed a marked increase among all urinary components in EVL and EC-MPA patients. Major changes involved typical components of glomerular damage: albumin, Zn-alpha1 glycoprotein, alpha2HS glycoprotein, and leucine-rich alpha2 glycoprotein. In addition, we observed specific biomarkers for EVL: clusters of alpha1-antitrypsin fragments and monoclonal lambda chains. In conclusion, EVL induced proteinuria of a mixed glomerular and tubular origin that correlated with the start of treatment and reached nephrotic ranges in few cases. The specific urinary markers may reflect renal alterations related to the transplant or specific alterations associated with the drug.
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PMID:Posttransplant proteinuria associated with everolimus. 1946 May 21

Posttransplantation B-lymphoproliferative (PTBL) disease is a severe complication of organ transplantation, which requires reduction of immunosuppressive treatment. The use of the anti-CD20 monoclonal antibody, Rituximab, improves the survival of these patients. In this setting, maintenance immunosuppressive therapy may represent a challenge. The mammalian target of rapamycin (m-TOR) inhibitor Rapamycin has antiproliferative effects that makes it a safe, efficient option to avoid graft rejection and reduce the malignancy risk. We studied 6 renal recipients (4 men and 2 women) of overall mean age of 50.66 +/- 15.89 years who were diagnosed with lymphoma at a mean time of graft function of 137.0 +/- 68.00 months. All of the patients were Epstein-Barr-negative. Four received a combination of Rituximab and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), and 2 received Rituximab only. In all cases complete remission persisted during follow-up of 21.83 +/- 8.34 months. The immunosuppressive treatment was switched to the m-TOR inhibitor Rapamycin at therapeutic trough blood levels of 5-8 ng/dL. The mean time of Rapamycin treatment was 15.5 +/- 8.96 months. Notably, we observed neither acute rejection nor relapse episodes. Renal function remained stable with no significant proteinuria. The serum creatinine level before switching to Rapamycin was 1.06 +/- 0.16 mg/dL and 0.9 +/- 0.14 mg/dL 12 months later. However, 1 patient had to stop Rapamycin treatment due to pneumonitis. Our study suggests that immunosuppressant monotherapy with Rapamycin is safe and efficient for renal recipients who develop lymphoma because of its antitumor effects without nephrotoxicity.
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PMID:Monotherapy rapamycin in renal transplant recipients with lymphoma successfully treated with rituximab. 1971 44


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