Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mammalian target of rapamycin (mTOR) is a conserved serine-threonine kinase that regulates cell growth and metabolism in response to nutrient signals. However, the specific involvement of mTOR in regulation of energy metabolism is poorly understood. To determine if signaling via mTOR might be directly involved in regulation of fatty acid metabolism in hepatocytes, we performed studies with rapamycin, a specific inhibitor of mTOR. Rapamycin-mediated inhibition of mTOR (18-48 hours) increased oxidation of exogenous fatty acids (46%-100%, respectively). In addition, esterification of exogenous fatty acids and de novo lipid synthesis were reduced (40%-60%, respectively). Consistent with inhibition of lipogenic pathways, rapamycin decreased expression of genes encoding acetyl-coenzyme A carboxylase I and mitochondrial glycerol phosphate acyltransferase. Non-insulin-dependent glucose transport and glycogen synthesis were decreased by 20% to 30%, whereas glucose utilization was unaffected by rapamycin. The data suggest that the hyperlipidemia observed with the drug in vivo is likely not the result of enhanced hepatic synthesis, but rather of delayed peripheral clearance. However, these results are consistent with the idea that mTOR may play a significant role, not only in "energy sensing," but also in regulation of energy production through profound effects on hepatic fatty acid metabolism.
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PMID:The mammalian target of rapamycin regulates lipid metabolism in primary cultures of rat hepatocytes. 1795 Jan

Sirolimus (SRL) has become an option in kidney transplantation, especially among patients who develop chronic allograft nephropathy (CAN). This study sought to evaluate the safety and efficacy of SRL in 103 kidney recipients of mean age 40 years, including 78 recipients of organs from deceased donors. The major reason for conversion was calcineurin inhibitor (CNI) nephrotoxicity (42.3%) followed by CAN (35.4%). A preconversion kidney biopsy was performed in 89 patients with CAN diagnosed in 51. Mean time to conversion was 40.5 months. The new therapy was: SRL/mycophenolate mofetil (MMF)/prednisone (Pred) in 79 patients; SRL/tacrolimus (TAC)/Pred in 15; and other SRL combinations in 9. The target SRL trough level was 5.0 to 8.0 ng/mL. To evaluate the impact of conversion on renal function, we compared the proteinuria and inverse serum creatinine at 3 months before conversion, at conversion, and at 1, 3, 6, 12, and 24 months postconversion. The overall mean follow-up time was 13.2 months. The analysis showed significant improvement in renal function at month 1 postconversion (P<.05) with stabilization thereafter. The SRL/MMF combination frequently induced anemia and/or leukopenia (n=23). Infections included pneumonia (n=10), herpes zoster (n=7), herpes simplex (n=3), cytomegalovirus (n=2), histoplasmosis (n=2), tuberculosis (n=2), and neurocryptococcosis (n=1). Reasons for SRL discontinuation were myelotoxicity (n=4), infection (n=3), nephrotoxicity (n=3), gastrointestinal intolerance (n=3), myopathy (n=1), pneumonitis (n=1), hyperlipidemia (n=1), and other reasons (n=3). Graft loss occurred in 29 patients due to CAN (n=21) followed by death (cardiovascular, n=2; infectious, n=2), acute rejection (n=3), and infection following immunosuppression withdrawal (n=1). We concluded that SRL represented an option but reducing associated immunosuppression should strongly be considered to minimize the frequent side effects, especially infections.
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PMID:Posttransplantation conversion to sirolimus-based immunosuppression: a single center experience. 1808 30

Cardiovascular disease is the major cause of death in renal transplant recipients. Renal transplant recipients share the same cardiovascular risk factors as the general population, including hypertension, hyperlipidemia, diabetes mellitus, smoking, and positive family history. However, renal transplant recipients are also exposed to transplant-specific risk factors such as chronic immunosuppression. Most renal transplant recipients receive combinations or permutations of immunosuppressive drugs including a calcineurin inhibitor (cyclosporine or tacrolimus), a mammalian target of rapamycin (mTOR) inhibitor (sirolimus), an antiproliferative drug (mycophenolate mofetil and azathioprine), and corticosteroids. Cyclosporine and tacrolimus can induce glucose intolerance, hypertension, and hyperlipidemia. Sirolimus can induce hyperlipidemia. Corticosteroids can induce glucose intolerance, hypertension, hyperlipidemia, and weight gain. Central to the development of metabolic complications in renal transplant recipients is insulin resistance induced by immunosuppressive drugs. Insulin resistance is considered to be the central pathophysiological feature of metabolic syndrome, which is linked to increased risk of cardiovascular disease and to chronic renal failure. Therefore, metabolic syndrome likely contributes to cardiovascular disease and chronic renal allograft dysfunction in renal transplant recipients. Treatment of metabolic complications in renal transplant recipients is difficult, as conversion to an alternate immunosuppressive drug may lead to introduction of new metabolic complications, and as discontinuation of immunosuppressive therapy may lead to rejection. Future research should focus on designing immunosuppressive regimens that have minimal effects on insulin resistance and metabolic complications but that are effective in preventing acute rejection and in prolonging both allograft and patient survival.
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PMID:Immunosuppression and metabolic syndrome in renal transplant recipients. 1837 Jun 95

As a key regulator of cholesterol homeostasis, sterol-regulatory element binding protein-2 (SREBP-2) up-regulates expression of genes involved in cholesterol synthesis (e.g., 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) Reductase) and uptake (the low density lipoprotein (LDL)-receptor). Previously, we showed that Akt, a critical kinase in cell growth and proliferation, contributes to SREBP-2 activation. However, the specific Akt target involved is unknown. A potential candidate is the mammalian target of rapamycin, mTOR. Rapamycin can cause hyperlipidaemia clinically, and we hypothesised that this may be mediated via an effect of mTOR on SREBP-2. Herein, we found that SREBP-2 activation and HMG-CoA Reductase gene expression were unaffected by rapamycin treatment. However, LDL-receptor gene expression was decreased by rapamycin, suggesting that this may contribute to the hyperlipidaemia observed in rapamycin-treated patients. Rapamycin did not affect mRNA stability, so the decrease in LDL-receptor gene expression is likely to be occurring at the transcriptional level, although independently of SREBP-2.
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PMID:Rapamycin down-regulates LDL-receptor expression independently of SREBP-2. 1860 94

Cardiovascular disease (CVD) accounts for 35% to 50% of deaths among renal transplant recipients. Beside the atherogenic risk factors related to hemodialysis, renal function, and use of immunosuppressive agents, other relevant risk factors for CVD include acute rejection episodes, microalbuminuria (muAlb), diabetes, arterial hypertension, lipid disorders, inflammatory triggers, hyperhomocysteinemia, anemia, erythrocytosis, obesity, and hyperuricemia. We studied the prevalence of risk factors and the impact of various drugs on CVD among 103 renal transplant recipients with measured glomerular filtration rates showing values >45 mL/min. We measured uric acid, triglycerides (TG), low-density lipoprotein (LDL)/high-density lipoprotein (HDL) LDL/HDL ratio, homocysteine (HOMO), insulin resistance, muAlb, C-reactive protein (CRP), and fibrinogen. Subsequently, patients were divided into 8 groups based on the immunosuppressive protocol to evaluate its impact on CVD risk factors. Insulin resistance and hyperhomocysteinemia were present in >2/3 of patients. Considering the impact of protocols, the combination of cyclosporine (CsA) + everolimus (EVL) resulted in the most favorable profile in terms of reduction of hyperuricemia, hyperlipidemia, and hyperhomocysteinemia. Insulin resistance tended to be more frequent among patients treated with protocols including calcineurin inhibitors (CNI) and steroids. The prevalence of hyperhomocyteinemia was similar among patients on CsA and on tacrolimus (Tac). Sirolimus (SRL) was associated with higher levels of HOMO. The combination of CNI and proliferative signal inhibitors (PSI) seemed to be the most promising one to reduce the impact of CVD risk factors. The reduction in CVD morbidity can improve expectancy and quality of life, as well as graft function and survival among renal transplant patients.
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PMID:Immunosuppressive agents and metabolic factors of cardiovascular risk in renal transplant recipients. 1946 May 10

Renal transplant recipients have increased mortality rates when compared with the general population. The new immunosuppressive drugs have improved short-term patient survival up to 95% at 1-2 years, but these data have to be confirmed in long-term follow-up. Furthermore, no particular regimen has proved to be superior over others with regard to patient survival. Cardiovascular diseases are the most common cause of mortality in renal transplant recipients and while no immunosuppressive drug has been directly associated with cardiovascular events, immunosuppressive drugs have different impacts on traditional risk factors. Corticosteroids and ciclosporin are the agents with the most negative impact on weight gain, blood pressure and lipids. Tacrolimus increases the risk of new-onset diabetes mellitus. Sirolimus and everolimus have the most impact on risk factors for post-transplant hyperlipidaemia. Modifications in immunosuppression could improve the cardiovascular profile but there is little evidence regarding the beneficial effects of these changes on patient outcomes. Malignancies are also an increasing cause of mortality, overtaking cardiovascular disease in some series. Induction therapy, azathioprine and calcineurin inhibitors (CNIs) are probably the immunosuppressive agents most linked with post-transplant malignancies. Mycophenolate mofetil (MMF) has no negative impact on the incidence of malignancies. Target of rapamycin (mTOR) inhibitors have antioncogenic properties and they are associated with a lower incidence of malignancies. In addition, these agents have been recommended for use to decrease the dose or withdrawal of CNIs in patients with malignancies. Infections are still an important cause of morbidity and mortality in renal transplant recipients. Some immunosuppressive agents such as MMF increase the incidence of cytomegalovirus infection and the need for prophylactic measures in risk recipients. The use of potent immunosuppressive therapy has resulted in the appearance of BK virus nephropathy, which progresses to graft failure in a high percentage of patients. Although first associated with tacrolimus and MMF immunosuppression, recent data suggest that BK nephropathy appears with any kind of triple therapy. In conclusion, reducing risk factors for patient death should be a major target to improve outcomes after renal transplantation. Effort should be made to control cardiovascular diseases, malignancies and infections with improved use of immunosuppressive drugs. Preliminary results with belatacept suggest its safety and efficacy, and open new perspectives in the immunosuppression of de novo renal transplant recipients.
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PMID:Immunosuppressive drugs in kidney transplantation: impact on patient survival, and incidence of cardiovascular disease, malignancy and infection. 1985 26

BACKGROUND.: Sirolimus (SRL) is an important component of clinical immunosuppression in renal transplantation, but few international studies have examined how this agent is used in routine practice. METHODS.: Within a large prospective pharmacoepidemiological study, 718 de novo renal graft recipients treated with SRL in 65 centers in 10 countries were monitored for up to 5 years posttransplant to compare the principal outcomes and adverse effects by treatment regimen. RESULTS.: Principal treatment regimens were SRL without a calcineurin inhibitor (33%), SRL+cyclosporine A (CsA) (33%), and SRL+tacrolimus (TAC) (34%); 18% of subjects discontinued SRL, 124/718 (17%) developed biopsy-confirmed acute rejection (BCAR), 64/718 (9%) lost their graft, and 50/718 (7%) died during follow-up. Calculated creatinine clearance was 66+/-26 mL/min at 2 years. The most common adverse events were hypertension, hyperlipidemia, anemia, urinary tract infections, and diabetes. BCAR was significantly lower in subjects receiving SRL+TAC (hazard ratio [HR] 0.46, P=0.009) but not significantly lower in those receiving SRL+CsA (HR 0.62, P=0.102) compared with SRL without a calcineurin inhibitor. Graft loss or death did not significantly differ between treatment groups but were associated, respectively, with deceased donor grafts (HR 3.33, P<0.001) and increased age (HR 1.04, P<0.001). No improvement was observed in patients receiving mycophenolate mofetil in any treatment combination (HR 0.80, P=0.438 for BCAR; HR 0.93, P=0.849 for graft loss; and HR 0.75, P=0.531 for death). CONCLUSIONS.: SRL is most commonly used in combination with mycophenolate mofetil, CsA, or TAC. BCAR was least common in subjects receiving SRL+TAC, but other outcomes seemed comparable between the treatment regimens in routine practice.
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PMID:Prospective observational study of sirolimus as primary immunosuppression after renal transplantation. 1985 47

Sirolimus (SRL) is a mammalian target of rapamycin inhibitor, which provides an immunosuppressive effect by inhibiting cell cycle progression. The encouraging results of combined SRL-cyclosporine therapy paved the way to further immunosuppressant combinations. Although SRL is relatively non-nephrotoxic when administered as monotherapy, it pharmacodynamically enhances the toxicity of calcineurin inhibitors. Other side effects may include hyperlipidemia and myelosuppression and less commonly wound healing impairment, proteinuria, edema and pneumonitis. Surprisingly, SRL also showed encouraging properties as an antiatherogenic and antineoplastic, opening a large spectrum of new potential applications. Whether SRL can be used safely over the long term with low doses of calcineurin inhibitors requires further study. The use of SRL as a corticosteroid-sparing agent also remains to be proven in controlled trials.
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PMID:Sirolimus in solid organ transplantation: current therapies and new frontiers. 2209 84

Sirolimus and its derivate everolimus are two immunosuppressive drugs with similar chemical structure that inhibit the proliferation of T cells by interfering with a serine-threonine kinase, called mTOR. Apart from their immunosuppressive effects, these agents may also inhibit endothelial intimal proliferation, the replication of cytomegalovirus, and the development of certain cancers. The main dose-dependent adverse events of mTOR inhibitors are hyperlipidemia, thrombocytopenia, mucositis, edema, and proteinuria. The use of mTOR inhibitors in renal transplantation may allow to reduce the doses of calcineurin inhibitors. Withdrawal of calcineurin inhibitors is also possible and may improve renal function, but some patients do not tolerate this regimen because of side effects. Further studies are needed to assess the role of mTOR inhibitors in the long-term.
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PMID:The pros and the cons of mTOR inhibitors in kidney transplantation. 2437 8

The mammalian target of rapamycin (mTOR) inhibiting drug rapamycin (Sirolimus) has severe side effects in patients including hyperlipidemia, an established risk factor for atherosclerosis. Recently, it was shown that rapamycin decreases hepatic LDL receptor (LDL-R) expression, which likely contributes to hypercholesterolemia. Scavenger receptor, class B, type I (SR-BI) is the major HDL receptor and consequently regulating HDL-cholesterol levels and the athero-protective effects of HDL. By using the mTOR inhibitor rapamycin, we show that SR-BI is down-regulated in human umbilical vein endothelial cells (HUVECs). This reduction of SR-BI protein as well as mRNA levels by about 50% did not alter HDL particle uptake or HDL-derived lipid transfer. However, rapamycin reduced HDL-induced activation of eNOS and stimulation of endothelial cell migration. The effects on cell migration could be counteracted by SR-BI overexpression, indicating that decreased SR-BI expression is in part responsible for the rapamycin-induced effects. We demonstrate that inhibition of mTOR leads to endothelial cell dysfunction and decreased SR-BI expression, which may contribute to atherogenesis during rapamycin treatment.
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PMID:Inhibition of mTOR down-regulates scavenger receptor, class B, type I (SR-BI) expression, reduces endothelial cell migration and impairs nitric oxide production. 2471 82


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