Aubert Alexandre, Liu Amy, Kao Martin, Goeres Jenna, Richardson Katlyn C, Nierves Lorenz, Jung Karen, Nabai Layla, Zhao Hongyan, Orend Gertraud, Krawetz Roman, Lange Philipp F, Younger Alastair, Chan Jonathan, Granville David J
International Collaboration on Repair Discoveries (ICORD) Centre, British Columbia Professional Firefighters' Burn and Wound Healing Group, Vancouver Coastal Health Research Institute, and.
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
JCI Insight. 2024 Oct 30;9(23):e181935. doi: 10.1172/jci.insight.181935.
Rheumatoid arthritis (RA) is a common autoimmune disorder characterized by exacerbated joint inflammation. Despite the well-documented accumulation of the serine protease granzyme B (GzmB) in RA patient biospecimens, little is understood pertaining to its role in pathobiology. In the present study, tenascin-C (TNC) - a large, pro-inflammatory extracellular matrix glycoprotein - was identified as a substrate for GzmB in RA. GzmB cleaves TNC to generate 3 fragments in vitro: a 130 kDa fragment that remains anchored to the matrix and 2 solubilized fragments of 70 and 30 kDa. Mass spectrometry results suggested that the 30 kDa fragment contained the pro-inflammatory TNC C-terminal fibrinogen-like domain. In the synovial fluids of patients with RA, soluble levels of GzmB and TNC were significantly elevated compared with healthy controls. Further, immunoblotting revealed soluble 70 and 30 kDa TNC fragments in the synovial fluids of patients with RA, matching TNC fragment sizes generated by GzmB cleavage in vitro. Granzyme K (GzmK), another serine protease of the granzyme family, also cleaves TNC in vitro; however, the molecular weights of GzmK-generated TNC fragments did not correspond to TNC fragment sizes detected in patients. Our data support that GzmB, but not GzmK, contributes to RA through the cleavage of TNC.
类风湿性关节炎（RA）是一种常见的自身免疫性疾病，其特征是关节炎症加剧。尽管在RA患者生物样本中丝氨酸蛋白酶颗粒酶B（GzmB）的积累已有充分记录，但对其在病理生物学中的作用却知之甚少。在本研究中，腱生蛋白-C（TNC）——一种大型促炎性细胞外基质糖蛋白——被确定为RA中GzmB的底物。GzmB在体外切割TNC产生3个片段：一个130 kDa的片段仍锚定在基质上，以及2个70 kDa和30 kDa的可溶性片段。质谱结果表明，30 kDa片段包含促炎性TNC C端纤维蛋白原样结构域。在RA患者的滑液中，GzmB和TNC的可溶性水平与健康对照相比显著升高。此外，免疫印迹显示RA患者滑液中存在可溶性70 kDa和30 kDa的TNC片段，与体外GzmB切割产生的TNC片段大小相符。颗粒酶K（GzmK）是颗粒酶家族的另一种丝氨酸蛋白酶，也能在体外切割TNC；然而，GzmK产生的TNC片段的分子量与患者中检测到的TNC片段大小不对应。我们的数据支持GzmB而非GzmK通过切割TNC导致RA。
