sirolimus and Hyperhomocysteinemia

Ageing and hyperhomocysteinemia (HHcy) are important risk factors for cardiovascular diseases (CVDs). HHcy affects the occurrence of vascular diseases in the elderly. So far, the mechanism of HHcy-induced vascular ageing remains largely unknown. Autophagy level is significantly reduced in the ageing process, and restoring impaired autophagy to a normal state may be one of the possible ways to extend the expected longevity and lifespan in the future. In this study, we established the HHcy rat model by feeding a 2.5% methionine diet. Small animal ultrasound and the tail-cuff method indicated that the vascular pulse wave velocity (PWV) and pulse pressure (PP) of HHcy rats were increased significantly compared with the control group. Vascular morphology and structure have been changed in HHcy rats, including lumen dilation, increased collagen fibre deposition and increased p53/p21/p16 expression. In vitro, under the stimulation of homocysteine (500 μmol/L, 24 hours), the rat vascular smooth muscle cells (VSMCs) presented senescence, which was characterized by the increased expression of ageing-related markers, such as p16, p21 and p53 as well as increased senescence-associated beta-galactosidase (SA-β-gal) activity. Meanwhile, the autophagy level was decreased both in vivo and in vitro, shown as the increased level of autophagy substrate p62 and the reduced level of autophagy marker LC3 II/I in the thoracic aorta of HHcy rats and in Hcy-treated VSMCs, respectively. The senescence phenotype of VSMCs was reversed by increased autophagy levels induced by rapamycin. Our findings indicate that decreased autophagy of VSMCs is involved in hyperhomocysteinemia-induced vascular ageing.

Topics: Animals; Autophagy; Hyperhomocysteinemia; Male; Muscle, Smooth, Vascular; Pulse Wave Analysis; Rats; Sirolimus

Hyperhomocysteinemia (HHcy) is a highly-related risk factor in vascular smooth muscle cell (VSMC) phenotypic modulation and atherosclerosis. Growing evidence indicated that autophagy is involved in pathological arterial changes. However, the risk mechanisms by which homocysteine and VSMC autophagy interact with cardiovascular disease are poorly understood. This study verified the homocysteine-responsive endoplasmic reticulum protein promotion of VSMC phenotypic switching, and the formation of atherosclerotic plaque in vitro. We found that impaired autophagy, as evidenced by decreased levels of MAP1LC3B II/MAP1LC3B I, has a vital role in HHcy-induced human aortic (HA)-VSMC phenotypic switching, with a decrease in contractile proteins (SM α-actin and calponin) and an increase in osteopontin. Knockdown of the essential autophagy gene Atg7 by small interfering RNA promoted HA-VSMC phenotypic switching, indicating that impaired autophagy induces phenotypic switching in these cells. HHcy co-treatment with rapamycin triggered autophagy, which alleviated HA-VSMC phenotypic switching. Finally, we found that Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor for maintaining genomic stability by resisting oxidative stress and restoring autophagy, is closely involved in this process. HHcy clearly decreased KLF4 expression. KLF4-specific siRNA aggravated defective autophagy and phenotypic switching. Mechanistically, KLF4 regulated the HHcy-induced decrease in HA-VSMC autophagy via the m-TOR signaling pathway. In conclusion, these results demonstrated that the KLF4-dependent rapamycin signaling pathway is a novel mechanism underlying HA-VSMC phenotypic switching and is crucial for HHcy-induced HA-VSMCs with defective autophagy to accelerate early atherosclerosis.

Topics: Aorta; Atherosclerosis; Autophagy; Humans; Hyperhomocysteinemia; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Microtubule-Associated Proteins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenotype; Signal Transduction; Sirolimus

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.

Topics: Calcineurin Inhibitors; Cardiovascular Diseases; Cyclosporine; Drug Therapy, Combination; Everolimus; Female; Glomerular Filtration Rate; Humans; Hyperhomocysteinemia; Hyperlipidemias; Hyperuricemia; Immunosuppressive Agents; Kidney Transplantation; Lipoproteins, HDL; Middle Aged; Risk Factors; Sirolimus; Tacrolimus; Transplant Recipients