Gu Su-Xi, Li Xin, Hamilton John L, Chee Ana, Kc Ranjan, Chen Di, An Howard S, Kim Jae-Sung, Oh Chun-do, Ma Yuan-Zheng, van Wijnen Andre J, Im Hee-Jeong
Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA; Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA; Department of Orthopedic Surgery, PLA309 Hospital, Beijing 100091, China.
Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA.
Gene. 2015 Jan 25;555(2):80-7. doi: 10.1016/j.gene.2014.10.024. Epub 2014 Oct 12.
Because miR-146a expression in articular chondrocytes is associated with osteoarthritis (OA), we assessed whether miR-146a is linked to cartilage degeneration in the spine. Monolayer cultures of nucleus pulposus (NP) cells from the intervertebral discs (IVD) of bovine tails were transfected with a miR-146a mimic. To provoke inflammatory responses and catabolic extracellular matrix (ECM) degradation, cells were co-treated with interleukin-1 (IL-1). Transfection of miR-146a decreases IL-1 induced mRNA levels of inflammatory genes and catabolic proteases in NP cells based on quantitative real-time reverse transcriptase PCR (qRT-PCR) analysis. Similarly, miR146a suppresses IL-1 induced protein levels of matrix metalloproteinases and aggrecanases as revealed by immunoblotting. Disc segments from wild type (WT) and miR-146a knockout (KO) mice were cultured ex vivo in the presence or absence of IL-1 for 3days. Histological and immuno-histochemical (IHC) analyses of disc organ cultures revealed that IL-1 mediates changes in proteoglycan (PG) content and in-situ levels of catabolic proteins (MMP-13 and ADAMTS-5) in the nucleus pulposus of the disc. However, these IL-1 effects are more pronounced in miR-146a KO discs compared to WT discs. For example, absence of miR-146a increases the percentage of MMP-13 and ADAMTS-5 positive cells after treatment with IL-1. Thus, miR-146a appears to protect against IL-1 induced IVD degeneration and inflammation. Stimulation of endogenous miR-146a expression or exogenous delivery of miRNA-146a are viable therapeutic strategies that may decelerate disc degeneration and regain a normal homeostatic balance in extracellular matrix production and turn-over.
由于关节软骨细胞中miR-146a的表达与骨关节炎（OA）相关，我们评估了miR-146a是否与脊柱软骨退变有关。用miR-146a模拟物转染来自牛尾椎间盘（IVD）的髓核（NP）细胞的单层培养物。为了引发炎症反应和分解代谢的细胞外基质（ECM）降解，细胞与白细胞介素-1（IL-1）共同处理。基于定量实时逆转录酶PCR（qRT-PCR）分析，miR-146a转染降低了IL-1诱导的NP细胞中炎症基因和分解代谢蛋白酶的mRNA水平。同样，免疫印迹显示miR146a抑制IL-1诱导的基质金属蛋白酶和聚集蛋白聚糖酶的蛋白水平。野生型（WT）和miR-146a基因敲除（KO）小鼠的椎间盘节段在有或没有IL-1的情况下离体培养3天。椎间盘器官培养物的组织学和免疫组织化学（IHC）分析表明，IL-1介导椎间盘髓核中蛋白聚糖（PG）含量和分解代谢蛋白（MMP-13和ADAMTS-5）原位水平的变化。然而，与WT椎间盘相比，这些IL-1效应在miR-146a KO椎间盘中更明显。例如，在用IL-1处理后，miR-146a的缺失增加了MMP-13和ADAMTS-5阳性细胞的百分比。因此，miR-146a似乎可以保护椎间盘免受IL-1诱导的退变和炎症。刺激内源性miR-146a表达或外源性递送miRNA-146a是可行的治疗策略，可能会减缓椎间盘退变，并在细胞外基质产生和周转方面恢复正常的稳态平衡。
