1,25(OH)2D3 improves blood lipid metabolism, liver function, and atherosclerosis by constraining the TGF-β/Smad signaling pathway in rats with hyperlipidemia

Abstract

1,25(OH)₂D₃ has already been reported to function in some diseases. However, its role in hyperlipidemia (HLP) remains unknown. This study aims to investigate the effect of 1,25(OH)₂D₃ on HLP rats. Rat models were established by high-fat diet feeding, perfusion of different doses of 1,25-(OH)₂D₃ and injection of TGF-β1 siRNA. Whole blood viscosity, plasma viscosity, hematocrit, and erythrocyte aggregation index were detected, together with levels of biochemical indexes, 6-keto-PGF1α, and TXB2 in serum. Levels of oxidative stress indexes and inflammatory factors in serum and liver tissues were determined. TGF-β1 and Smad3 expression in serum, liver tissues, and aorta was detected. 1,25(OH)₂D₃ lowered HLP-induced rise of whole blood viscosity, red blood cell aggregation index, plasma viscosity, and hematocrit, TC, TG, LDL-C, apoB, ALT, AST, TXB2, MDA, IL-1β, TNF-α, and increased HLP-induced decrease of HDL-C, apoAI, 6-keto-PGF1α, SOD, GSH-Px, CAT, and T-AOC. TGF-β1 and Smad3 expression in serum, liver tissue, and aorta of 1,25(OH)₂D₃-treated rats reduced. High 1,25(OH)₂D₃ dose and inhibited TGF-β/Smad signaling pathway alleviated lipid metabolism, liver function, and atherosclerotic injury in HLP rats. Our study found that 1,25(OH)₂D₃ improves blood lipid metabolism, liver function, and atherosclerosis injury by constraining the TGF-β/Smad signaling pathway in rats with HLP.

Keywords: 1; 25(OH)D; TGF-β/Smad signaling pathway; lipid metabolism.

Figure 1.

1,25(OH)₂D₃ and TGF-β1 silencing decline intima-media thickness of HLP rats. (a) color Doppler ultrasound images of abdominal aorta of all rats; (b) intima-media thickness of abdominal aorta of all rats; the data in the figure were all measurement data expressed as mean ± standard deviation, ANOVA was used for comparisons among multiple groups, and the LSD t-test was used for pairwise comparisons after one-way ANOVA; *, P < 0.05 vs the normal group; #, P < 0.05 vs the HLP group; &, P < 0.05 vs the H-1,25(OH)₂D₃ group.

Figure 2.

High-dose 1,25(OH)₂D₃ and TGF-β1 silencing decrease TC, TG, LDL-C, apoB, and TXB2 contents and ALT and AST activity, and increase HDL-C, apoAI, and 6-Keto-PGF1α contents of HLP rats. (a) TC, TG, HDL-C, LDL-C contents in rats’ serum; (b) apoAI and apoB contents in rats’ serum; (c) ALT and AST contents in rats’ serum; (d) 6-keto-PGF1α and TXB2 contents in rats’ serum; the data in the figure were all measurement data expressed as mean ± standard deviation, ANOVA was used for comparisons among multiple groups, and the LSD-t test was used for pairwise comparisons after one-way ANOVA; *, P < 0.05 vs the normal group; #, P < 0.05 vs the HLP group; &, P < 0.05 vs the H-1,25(OH)₂D₃ group.

Figure 3.

High-dose 1,25(OH)₂D₃ and TGF-β1 silencing increase SOD, GSH-Px, CAT and T-AOC activities, and decline MDA, IL-1β and TNF-α contents of HLP rats. (a) SOD and GSH-Px activity in rats’ serum; (b) CAT activity and T-AOC level in rats’ serum; (c) MDA content in rats’ serum; (d) TNF-α and IL-1β content in rats’ serum; the data in the figure were all measurement data expressed as mean ± standard deviation, ANOVA was used for comparisons among multiple groups, and the LSD t-test was used for pairwise comparisons after one-way ANOVA; *, P < 0.05 vs the normal group; #, P < 0.05 vs the HLP group; &, P < 0.05 vs the H-1,25(OH)₂D₃ group.

Figure 4.

1,25(OH)₂D₃ and TGF-β1 silencing improve liver tissue morphology of HLP rats. (a) HE staining images of rats’ liver tissues in each group; (b) Oil red O staining images of rats’ liver tissues in each group; (c) TEM images of rats’ liver tissues in each group (N, nucleus; M, mitochondrion; L, lipid droplet).

Figure 5.

1,25(OH)₂D₃ and TGF-β1 silencing increase SOD, GSH-Px, CAT and T-AOC activities and diminish MDA, L-1β and TNF-α contents of HLP rats. (a) changes in SOD, GSH-Px, and CAT activity in liver tissues of rats in each group; (b) changes in T-AOC levels in liver tissues of rats in each group; (c) changes of MDA content in liver tissues of rats in each group; (d) changes of TNF-α and IL-1β contents in liver tissues of rats in each group; the data in the figure were all measurement data expressed as mean ± standard deviation, ANOVA was used for comparisons among multiple groups, and the LSD t-test was used for pairwise comparisons after one-way ANOVA; *, P < 0.05 vs the normal group; #, P < 0.05 vs the HLP group; &, P < 0.05 vs the H-1,25(OH)₂D₃ group.

Figure 6.

1,25(OH)₂D₃ and TGF-β1 silencing improve the aortic tissue structure of HLP rats. (a) HE staining images of large aortic tissues of rats in each group (× 200); (b) Oil red O staining images of aortic tissues of rats in each group (× 400).

Figure 7.

High-dose 1,25(OH)2D regulates blood lipid metabolism, optimizes liver function, and treats atherosclerosis by constraining TGF-β/Smad signaling pathway. (a) detection of the mRNA contents of TGF-β1 and Smad3 in rats’ serum in each group by RT-qPCR; (b) detection of the protein expression of TGF-β1 and Smad3 in rats’ serum in each group by Western blot analysis; (c) detection of the mRNA contents of TGF-β1 and Smad3 in rats’ liver tissues in each group by RT-qPCR; (d) detection of the protein expression of TGF-β1 and Smad3 in rats’ liver tissues in each group by Western blot analysis; (e) detection of the mRNA contents of TGF-β1 and Smad3 in rats’ aortic tissues in each group by RT-qPCR; F, detection of the protein expression of TGF-β1 and Smad3 in rats’ aortic tissues in each group by Western blot analysis; the data in the figure were all measurement data expressed as mean ± standard deviation, ANOVA was used for comparisons among multiple groups, and the LSD t-test was used for pairwise comparisons after one-way ANOVA; *, P < 0.05 vs the normal group; #, P < 0.05 vs the HLP group; &, P < 0.05 vs the H-1,25(OH)₂D₃ group.