氧化型低密度脂蛋白（oxLDL）可损害人肌腱细胞中的 TGF-β活性。

Exposure to oxLDL impairs TGF-β activity in human tendon cells.

机构信息

Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, Canada.

Department of Orthopaedics, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada.

出版信息

BMC Musculoskelet Disord. 2023 Mar 16;24(1):197. doi: 10.1186/s12891-023-06308-x.

DOI:10.1186/s12891-023-06308-x

PMID:36927534

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10018928/

Abstract

BACKGROUND

Previous studies have shown that patients with hypercholesterolemia experience elevated levels of oxidized LDL (oxLDL), a molecule which triggers inflammation and collagenase activity. In this study we discovered novel mechanistic effects of oxLDL on tendon cells and the mediators regulating matrix remodeling by analyzing the expression and activity of related proteins and enzymes. These effects may contribute to tendon damage in patients with high cholesterol.

METHODS

Isolated human tendon cells (male and female donors age 28 ± 1.4 age 37 ± 5.7, respectively) were incubated in the presence or absence of oxLDL. The influence of oxLDL on the expression level of key mRNA and proteins was examined using real time quantitative PCR, ELISA and Western blots. The activities of enzymes relevant to collagen synthesis and breakdown (lysyl oxidase and matrix metalloproteinases) were quantified using fluorometry. Finally, the isolated human tendon cells in a 3D construct were exposed to combinations of oxLDL and TGF-β to examine their interacting effects on collagen matrix remodeling.

RESULTS

The one-way ANOVA of gene expression indicates that key mRNAs including TGFB, COL1A1, DCN, and LOX were significantly reduced in human tendon cells by oxLDL while MMPs were increased. The oxLDL reduced the activity of LOX at 50 µg/ml, whereas conversely MMP activities were induced at 25 µg/ml (P ≤ 0.01). COL1A1 synthesis and TGF-β secretion were also inhibited (P ≤ 0.05). Adding recombinant TGF-β reversed the effects of oxLDL on the expression of collagens and LOX. OxLDL also impaired collagen matrix remodeling (P ≤ 0.01), and adding TGF-β restored the native phenotype.

CONCLUSION

Exposure to oxLDL in patients with hypercholesterolemia may adversely affect the mechanical and structural properties of tendon tissue through a direct action of oxLDL on tendon cells, including impairment of TGF-β expression. This impairment leads to disturbed matrix remodeling and synthesis, thereby potentially leading to increased risk of acute or chronic tendon injury. Our discovery may provide an opportunity for developing effective treatments for tendon injury in hypercholesterolemia patients by targeting the TGF-β pathway.

摘要

背景

先前的研究表明，高胆固醇血症患者的氧化型 LDL（oxLDL）水平升高，oxLDL 是一种触发炎症和胶原酶活性的分子。在这项研究中，我们通过分析相关蛋白和酶的表达和活性，发现了 oxLDL 对肌腱细胞的新的作用机制，以及调节基质重塑的介质。这些作用可能导致高胆固醇血症患者的肌腱损伤。

方法

分离的人肌腱细胞（男性和女性供体年龄分别为 28±1.4 岁和 37±5.7 岁）在存在或不存在 oxLDL 的情况下孵育。使用实时定量 PCR、ELISA 和 Western blot 检测 oxLDL 对关键 mRNA 和蛋白表达水平的影响。使用荧光法定量与胶原合成和分解相关的酶（赖氨酰氧化酶和基质金属蛋白酶）的活性。最后，将分离的人肌腱细胞在 3D 构建体中暴露于 oxLDL 和 TGF-β 的组合中，以研究它们对胶原基质重塑的相互作用效应。

结果

基因表达的单因素方差分析表明，包括 TGFB、COL1A1、DCN 和 LOX 在内的关键 mRNAs 在人肌腱细胞中被 oxLDL 显著下调，而 MMPs 则被上调。oxLDL 在 50μg/ml 时降低 LOX 的活性，而相反地，MMP 活性在 25μg/ml 时被诱导（P≤0.01）。COL1A1 的合成和 TGF-β 的分泌也受到抑制（P≤0.05）。添加重组 TGF-β 逆转了 oxLDL 对胶原和 LOX 表达的影响。oxLDL 还损害了胶原基质的重塑（P≤0.01），添加 TGF-β 恢复了天然表型。

结论

在高胆固醇血症患者中，oxLDL 的暴露可能通过 oxLDL 对肌腱细胞的直接作用，对肌腱组织的机械和结构特性产生不利影响，包括对 TGF-β 表达的损害。这种损害导致基质重塑和合成的紊乱，从而可能增加急性或慢性肌腱损伤的风险。我们的发现为通过靶向 TGF-β 途径为高胆固醇血症患者的肌腱损伤提供了有效的治疗机会。