Effect of cholesterol on human meniscal fibrochondrocytes / 中华创伤骨科杂志

ABSTRACT

Objective:To explore the effect of cholesterol on the expression of genes for matrix synthesis and degradation of human meniscal fibrochondrocytes and its mechanism.Methods:Meniscal tissue was taken from patients undergoing arthroscopic surgery to extract fibrochondrocytes. The cells were divided into a control group in which the normal cells were not processed, a positive control group in which interleukin-1 β was used to create a degeneration model, and 2 treatment groups which were subjected to treatment with 15 and 30 μg/mL cholesterol respectively. Safranin O staining, β-galactosidase staining and enzymic kits were used to detect the morphology and total cholesterol (TCH) content of meniscal fibrochondrocytes in the 4 groups. Immunofluorescence and western blot were used to detect the protein expression of type Ⅰcollagen precursor α1 (COL1A1) and type Ⅱ collagen precursor α1 (COL2A1). RT-qPCR was used to detect the mRNA expression of COL1A1, COL2A1, matrix metalloproteinase (MMP) 3, MMP9, MMP13, and genes related to cholesterol efflux pathways [like liver X receptor α (LXR α), ATP binding cassette transporter A1 (ABCA1) and ABCG1]. Results:There was no significant difference between the control and the positive control groups in the TCH content in human meniscal fibrochondrocytes ( P>0.05). The treatments with 15 and 30 μg/mL cholesterol resulted in significantly increased TCH contents in human meniscal fibrochondrocytes in the treatment groups ( P<0.05). Compared with the control group, the mRNA expression of LXR α, ABCA1 and ABCG1 was significantly decreased in the treatment groups ( P<0.05), and the meniscal fibrochondrocytes in the positive group and the treatment groups presented with a lower density, chaotic distribution and obvious signs of degradation. Compared with the control groups, the mRNA expression of matrix synthesis genes (COL1A1 and COL2A1) in the meniscal fibrochondrocytes was significantly inhibited while the mRNA expression of matrix degradation metalloenzymes (MMP3, MMP9 and MMP13) was significantly promoted ( P<0.05). Conclusion:Cholesterol may inhibit the cholesterol efflux pathways of meniscal fibrochondrocytes, and thus cause accumulation of cholesterol in the meniscal fibrochondrocytes, eventually leading to degeneration of meniscus.