Expression of LOX-1 in human mesangial cells is increased by Ox-LDL and IL-1β treatment

Abstract

The present study aimed to determine whether the expression of lectin-like oxidized LDL receptor 1 (LOX-1) could be induced by oxidized low-density lipoprotein (Ox-LDL) and interleukin 1β (IL-1β) in human mesangial cells (HMCs). Oil Red O staining was used to observe the uptake of Ox-LDL by HMCs stimulated with IL-1β, and reverse transcription-quantitative polymerase chain reaction analysis and western blotting were used to examine the expression of LOX-1 in HMC following Ox-LDL and IL-1β treatment. Uptake of Ox-LDL by HMCs was upregulated upon stimulation with IL-1β. Furthermore, Ox-LDL (10-40 µg/ml) treatment induced LOX-1 mRNA and protein expression in a dose-dependent manner. In addition, when HMCs were treated with IL-1β and Ox-LDL, the expression of LOX-1 was enhanced further. These results indicated that inhibiting LOX-1 expression or inhibiting the Ox-LDL/LOX-1 signaling axis may be a potential novel method for treating renal disease.

Keywords: human mesangial cell; interleukin 1β; lectin-like oxidized LDL receptor 1; oxidized low-density lipoprotein.

Figure 1.

IL-1β promotes the uptake of oxidized low-density lipoprotein by human glomerular mesangial cells. Oil Red O staining of the (A) untreated control and (B) 5 ng/ml IL-1β treatment groups (magnification, ×400). IL, interleukin.

Figure 2.

Ox-LDL promotes HMC apoptosis. Results of trypan blue staining and lactate dehydrogenase release test on HMCs treated with Ox-LDL (0–200 µg/ml). HMCs, human glomerular mesangial cells; Ox-LDL, oxidized low-density lipoprotein.

Figure 3.

Ox-LDL increases the expression of LOX-1 mRNA in human glomerular mesangial cells. Ox-LDL mRNA expression was measured by reverse transcription-quantitative polymerase chain reaction relative to GADPH. **P<0.01 vs. the control group. Ox-LDL, oxidized low-density lipoprotein; LOX-1, lectin-like oxidized LDL receptor 1.

Figure 4.

Ox-LDL and IL-1β combined treatment significantly increases the expression of LOX-1 mRNA in human glomerular mesangial cells compared with Ox-LDL treatment alone. Ox-LDL mRNA expression was measured by reverse transcription-quantitative polymerase chain reaction relative to GADPH. **P<0.01 vs. the control group; ^##P<0.01 vs. 40 µg Ox-LDL alone treatment; ^ффP<0.01 vs. 60 µg Ox-LDL alone treatment; ^◊◊P<0.01 vs. 5 ng/ml IL-1β alone treatment. Ox-LDL, oxidized low-density lipoprotein; IL, interleukin; LOX-1, lectin-like oxidized LDL receptor 1.

Figure 5.

Ox-LDL increases the expression of LOX-1 protein. Ox-LDL protein expression was measured by western blotting followed by densitometry. **P<0.01 and *P<0.05 vs. the control group. Ox-LDL, oxidized low-density lipoprotein; LOX-1, lectin-like oxidized LDL receptor 1.

Figure 6.

Ox-LDL and IL-1β combined treatment significantly increases the expression of LOX-1 protein in human glomerular mesangial cells compared with Ox-LDL treatment alone. Ox-LDL protein expression was measured by western blotting followed by densitometry. **P<0.01 vs. the control group; ^##P<0.01 vs. 40 µg Ox-LDL alone treatment; ^ффP<0.01 vs. 60 µg Ox-LDL alone treatment; ^◊◊P<0.01 vs. 5 ng/ml IL-1β alone treatment. Ox-LDL, oxidized low-density lipoprotein; IL, interleukin; LOX-1, lectin-like oxidized LDL receptor 1.