| Dyslipidemia is a common complication of nephritic disease and dyslipidaemia contributies to the progression of kidney disease and glomerulosclerosis. It is widely believed that glomerulosclerosis and atherosclerosis shared the same mechanism, Atherosclerosis, as we know it can increase the cardiovascular mortality, and it is more important in patients with chronic kidney disease because more than 50% of ESRD patients died from cardiovascular diseases. It has been demonstrated that atherosclerosis has features consistent with a chronic inflammatory disease and inflammation is also associated with many nephritic disease, consequently, it is reasonably believed that inflammation can accelerate the progression of glomerulosclerosis and modify lipid-mediated renal injury.It has been understood that oxidized low-density lipoprotein(Ox-LDL) plays an important role in atherosclerosis. In the study of atherosclerosis, a novel recepter for Ox-LDL named lectin-like oxidized low-density lipoprotein receptor(LOX-1), is considered as the initial and progressive factor through binding with Ox-LDL in atherosclerosis, ABCA1, a number of ATP-binding cassette transporter superfamily, mediates the cellular efflux of phospholipids and cholesterol and plays a significant role in high density lipourotein (HDL) metabolism and reverse cholesterol transport (RCT) protecting arteries from developing atherosclerosis. Inflammatory cytokines, such as TNF-α,IL-1βcan increase receptors of Ox-LDL in the pathology of atherosclerosis while whether it is with the same role in the glomerulosclerosis still waiting for clarify. The purpose of this study is to analysis 1) if the balance of cholesterol homeostasis on humanmesangial cell line (HMCL) could be regulated by LOX-1 and ABCA1; 2) if those effect of LOX-1 and ABCA1 can be changed by the stimulation of IL-1β; 3) if the protective effect from progression of kidney diseases of PPAR-γagonist mediated by the rgulation of the LOX-1 and ABCA1.Methods:1. To observe the uptake of Ox-LDL by HMCL stimulated by IL-1βusing Oil Red "0",con-focal microscopy and flow cytometry. 2. To examine the levels of LOX-1 on HMCL induced by IL-1βand Ox-LDL using Real-time PCR和Western Blot. 3. To examine the expression of ABCA1 on HMCL induced by IL-1β. 4. To observe the protective effect of PPAR-γagonist.Results:1. Uptake of Ox-LDL and Dil-Ox-LDL by HMCL was up-regulated upon stimulation with IL-1βin a dose and time-dependent manner. Intracellular mean fluorescence density of Dil-Ox-LDL with LOX-1 blocker of IL-1βstimulation group was decreased to 89.8％compared to that without blocker. The data suggested that IL-1βenhances uptake of Ox-LDL partly through the LOX-1 pathway.2. IL-1βcan induce LOX-1 mRNA and protein expression in a dose-dependent manner(2.5-10ng/ml). The peak level of LOX-1 mRNA reached after 6h of stimulation and was as high as 6.87-fold as contral. The up-regulation effect on LOX-1 protein reached peak after 24h and was as high as 1.88-fold as contral treated with 5ng/ml of IL-1β.3.Ox-LDL can induce LOX-1 mRNA and protein expression in a dose-dependent manner(10-40μg/ml)。The peak level of LOX-1 mRNA reached after 12h of stimulation and was as high as 3.73-fold as contral. The up-regulation effect on LOX-1 protein reached peak after 24h and was as high as 1.81-fold as contral treated with 40μg/ml of Ox-LDL. When HMCL was co-cultured with IL-1βand Ox-LDL, the up-regulation effect of Ox-LDL can still be enhanced by IL-1βon expressions of mRNA and protein.4. The expression of ABCA1mRNA and protein on lipid-loaded HMCL can be reduced by IL-1βin a time and dose-dependent manner. After stimulated with 5ng/ml of IL-1β, the expression of ABCA1mRNA and protein decreased to the lowest level of 19.0% and 50.62% of the baseline respectively.5. The increased of LOX-1mRNA and protein expression induced by IL-1βcould be offset by 15d-PGJ2 in a dose-dependent manner. The expression of ABCA1 inhibited by IL-1βcan be increased by co-cultured with 15d-PGJ2 in HMCL.Conclusions: The study suggests that the enhanced uptake of HMCL to Ox-LDL stimulated by IL-1βpartly through the LOX-1 pathway. The expression of LOX-1 can be up-regulated by IL-1βand Ox-LDL in a dose-dependent manner, and also the up-regulation effect of Ox-LDL on the expression of LOX-1 can be further enhance by the IL-1β. When stimulated with IL-1β, the expression of ABCA1 can be decreased in a time and dose-dependent manner. The expression of LOX-1 and ABCA1 induced by IL-1βcould be offset by 15d-PGJ2 in a dose-dependent which mean that PPAR-γagonist can influence the balance of cholesterol homeostasis of HMCL and have a protective effect for dyslipidemia enhanced by inflammatory cytokines. |
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