软骨下骨成骨细胞在骨性关节炎中的作用与机制

骨性关节炎是一种骨组织代谢疾病,软骨下骨成骨细胞直接参与骨性关节炎的病理过程。成骨细胞表达异常的生物学表型与软骨下骨结构和功能改变密切相关,其可使软骨承受更高的应力;软骨下骨成骨细胞产生的代谢调节因子通过骨和软骨间微结构直接促进软骨细胞退变。免疫和脂类代谢通过成骨细胞调节骨组织代谢,参与骨性关节炎病变过程。进一步阐明软骨下骨成骨细胞在骨性关节炎病变过程中的作用和机制,可为骨性关节炎研究和治疗提供新方法和思路。     

软骨细胞中内质网应激信号通路的研究进展

内外环境多种刺激均可导致内质网中未折叠蛋白的积聚,引起细胞内的应激反应,改变细胞的功能和存活状态,这个过程称为内质网应激（ERS）。软骨细胞是关节软骨内唯一的细胞成分,低糖性损伤、白细胞介素-1β和一氧化氮以及一些药物均能使其发生ERS。ERS可引发蛋白激酶R样内质网调节激酶（PERK）、肌醇需酶（IRE）1和活化转录因子（ATF）6三条主要的信号通路构成未折叠的蛋白反应（UPR）。UPR中多种信号分子对软骨细胞的生长、程序性死亡以及软骨的炎症都有重要的影响,本文就ERS信号通路机制、PERK信号通路、IRE1信号通路和ATF6信号通路等研究进展作一综述。     

Nitric oxide boosts TLR‐4 mediated lipocalin 2 expression in chondrocytes

Lipocalin 2 (LCN2) has recently emerged as a novel adipokine involved in different processes including arthritis and chondrocyte inflammatory response. However, little is known about its activity on chondrocyte homeostasis and its regulation by nitric oxide (NO) Hence, we performed a set of experiments aimed to achieve a better understanding of this relationship. Cell vitality was tested in the ATDC5 cell line by the MTT colorimetric assay. Protein expression and gene expression was evaluated by Western blot and real time RT‐PCR, respectively. NO production (determined as nitrite accumulation) was assayed by the Griess reaction. First, we demonstrated that LCN2 decreased murine chondrocytes vitality. Next, LCN2 co‐stimulation with LPS enhanced NOS2 protein expression by murine chondrocytes. In addition, inhibition of LPS‐induced nitric oxide production by aminoguanidine, a selective NOS2 inhibitor, significantly reduced LPS‐mediated LCN2 expression. In contrast, treatment of murine chondrocytes with sodium nitroprussiate (SNP), a classic NO donor, scarcely induced LCN2 expression. Intriguingly, SNP addition to LPS‐challenged chondrocytes, treated with aminoguanidine, provoked a strong induction of LCN2 expression. Finally, murine ATDC5 cells, co‐cultured with LPS pre‐challenged macrophages, had higher LCN2 expression in comparison with murine chondrocytes co‐cultured with non pre‐challenged macrophages. In this work we have described for the first time that NO is able to exert a control on LCN2 expression, suggesting the existence of a feedback loop regulating its expression. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1046–1052, 2013     

ABIN-1 protects chondrocytes from lipopolysaccharide-induced inflammatory injury through the inactivation of NF-κB signalling

The A20-binding inhibitor of nuclear factor (NF)-κB-1 (ABIN-1) protein has recently been implicated as a key regulator of inflammation with involvement in multiple inflammatory diseases. However, the function of ABIN-1 in osteoarthritis (OA) remains unclear. In the current study, we explored the role of ABIN-1 in the regulation of lipopolysaccharide (LPS)-induced inflammatory injury of chondrocytes, which served as an in vitro model of OA. Results revealed that ABIN-1 expression was induced by chondrocyte exposure to LPS. ABN-1 silencing exacerbated LPS-induced apoptosis and the inflammatory response, while ABIN-1 overexpression alleviated the inflammatory response and LPS-induced apoptosis in chondrocytes. Moreover, ABIN-1 overexpression resulted in significantly decreased LPS-induced NF-κB activation. Notably, activation of NF-κB signalling significantly reversed ABIN-1-mediated inhibitory effects on LPS-induced inflammatory injury in chondrocytes. Taken together, these results demonstrate that ABIN-1 protects chondrocytes against LPS-induced inflammatory injury through the suppression of NF-κB signalling. Our study suggests a potential role for ABIN-1 in OA. Further, we show that ABIN-1 may serve as a potential target for controlling joint inflammation.     

Increased expression and activation of cathepsin K in human osteoarthritic cartilage and synovial tissues

Few studies have analyzed Cathepsin K (CatK) expression in human osteoarthritic tissues. We investigated CatK expression and activation in human articular cartilage using clinical specimens. Human osteoarthritic cartilage was obtained during surgery of total hip arthroplasty (n = 10), and control cartilage was from that of femoral head replacement for femoral neck fracture (n = 10). CatB, CatK, CatL, CatS, and Cystatin C (CysC) expressions were evaluated immunohistochemically and by real‐time PCR. Intracellular CatK protein was quantified by ELISA. Intracellular CatK activity was also investigated. Osteoarthritis (OA) chondrocytes were strongly stained with CatK, particularly in the superficial layer and more damaged areas. CatB, CatL, CatS, and CysC were weakly stained. CatK mRNA expression was significantly higher in OA group compared to that in control group (p = 0.043), whereas those of CatB, CatL, CatS, and CysC did not differ significantly. Mean CatK concentration (4.83 pmol/g protein) in OA chondrocytes was higher than that (3.91 pmol/g protein) in control chondrocytes (p = 0.001). CatK was enzymatically more activated in OA chondrocytes as compared with control chondrocytes. This study, for the first time, revealed increased CatK expression and activation in human OA cartilage, suggesting possible crucial roles for it in the pathogenesis of osteoarthritic change in articular cartilage. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:127–134, 2016.     

Chondrocyte cultures from human proximal interphalangeal finger joints

Osteoarthritis (OA) of the hand is a common disease resulting in pain and impaired function. The pathogenesis of hand OA (HOA) is elusive and models to study it have not been described. Chondrocyte culture has been essential to understand cartilage degeneration, which is a hallmark of OA. We investigated the feasibility of human chondrocyte culture derived from proximal interphalangeal (PIP) finger joints. Hyaline cartilage of the PIP and knee joints was obtained from human cadavers. Chondrocytes harvested up to 236 h after death of the donors were viable and expressed chondrocyte‐specific genes. Gene expression comparing chondrocytes from PIP and knee joints using Affymetrix GeneChip arrays resulted in a unique PIP‐specific gene expression pattern. Genes involved in developmental processes including the WNT pathway were differentially expressed between the joints. These findings suggest that our knowledge on chondrocyte biology derived mainly from knee and hip joints may not apply to chondrocytes of the PIP joints and some of the distinctive features of HOA may be caused by the specific properties of PIP chondrocytes. Chondrocyte culture of PIP cartilage is a novel tool to study cartilage degeneration in HOA. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1569–1575, 2016.     

Long-term clinical results and MRI changes after autologous chondrocyte implantation in the knee of young and active middle aged patients

Background

Autologous chondrocyte implantation (ACI) represents a valid surgical option for symptomatic full-thickness chondral lesions of the knee. Here we report long-term clinical and MRI results of first-generation ACI.

Materials and methods

Fifteen patients (mean age 21.3 years) underwent first-generation ACI for symptomatic chondral defects of the knee between 1997 and 2001. The mean size of the lesions was 5.08 cm² (range 2–9 cm²). Patients were evaluated using the International Knee Documentation Committee (IKDC) Knee Examination Form, the Tegner Activity Scale, and the Knee Injury and Osteoarthritis Outcome Score (KOOS). High-resolution MRI was used to analyze the repair tissue with nine variables (the MOCART scoring system).

Results

The mean follow-up period was 148 months (range 125–177 months). ACI resulted in substantial improvements in all clinical outcome parameters, even as much as 12 years after implantation. A significant decrease in the MOCART score was recorded at final measurement. Reoperation was required in 2 patients; failure was caused by partial detachment of the graft in both cases.

Conclusion

Autologous chondrocyte implantation is an effective and durable solution for the treatment of large, full-thickness cartilage and osteochondral lesions, even in young and active middle-aged patients. High-resolution MRI is a useful and noninvasive method for evaluating the repaired tissue.

Level of evidence

IV.

     

姜黄素通过上调PPARγ抑制糖基化终末产物诱导的软骨细胞凋亡及线粒体功能损伤

目的观察姜黄素(curcumin)对糖基化终末产物(AGEs)诱导的软骨细胞凋亡及线粒体功能损伤的作用,并探讨相关机制是否与姜黄素上调过氧化物酶体增殖物激活受体-γ(PPARγ)相关。方法原代培养家兔膝关节软骨细胞;TUNEL染色法检测细胞凋亡;Rhodamine-123试剂盒检测线粒体跨膜电位(△Ψm);ATP试剂盒检测线粒体ATP生成;分光光度法检测caspase-3活性;Western blot检测PPARγ、细胞色素C、Bax及Bcl-2蛋白表达;real-time PCR检测PPARγmRNA含量;DNA-binding法检测PPARγ活性。结果 AGEs(200 mg·L-1)可明显诱导兔软骨细胞凋亡,同时线粒体跨膜电位(△Ψm)降低、ATP生成减少,caspase-3活性增加,细胞色素C释放增加,Bax/Bcl-2的比值增加;线粒体通透性转换孔的抑制剂环孢霉素A(Cs A,100 nmol·L-1)可以明显抑制AGEs诱导的细胞凋亡;PPARγ特异性激动剂吡格列酮及姜黄素均可明显抑制AGEs诱导的软骨细胞凋亡及线粒体功能损伤,给予PPARγ特异性抑制剂GW9662 10μmol·L-1预处理后,可以明显拮抗姜黄素的保护作用。同时,姜黄素可以明显上调AGEs诱导的PPARγ活性的降低,并伴随PPARγ相应的mRNA及蛋白表达水平的升高。结论姜黄素通过上调PPARγ,有效地保护AGEs诱导的软骨细胞线粒体损伤,从而抑制AGEs诱导的软骨细胞凋亡。