Blockade of TRPM7 Alleviates Chondrocyte Apoptosis and Articular Cartilage Damage in the Adjuvant Arthritis Rat Model Through Regulation of the Indian Hedgehog Signaling Pathway.

Ganggang Ma,Yong Chen,Xin Wei,Yang Yang,Jie Ding,Ren-Peng Zhou,Wei Hu

doi:10.3389/fphar.2021.655551

Abstract

Articular cartilage damage with subsequent impairment of joint function is a common feature of articular diseases, in particular, rheumatoid arthritis and osteoarthritis. While articular cartilage injury mediated by chondrocyte apoptosis is a known major pathological feature of arthritis, the specific mechanisms remain unclear at present. Transient receptor potential melastatin-like seven channel (TRPM7) is reported to play an important regulatory role in apoptosis. This study focused on the effects of TRPM7 on arthritic chondrocyte injury and its underlying mechanisms of action. Sodium nitroprusside (SNP)-induced rat primary chondrocyte apoptosis and rat adjuvant arthritis (AA) were used as in vitro and in vivo models, respectively. Blockage of TRPM7 with 2-APB or specific siRNA resulted in increased chondrocyte viability and reduced toxicity of SNP. Moreover, treatment with 2-APB enhanced the Bcl-2/Bax ratio and reduced cleaved PARP and IL-6, MMP-13 and ADAMTS-5 expression in SNP-treated chondrocytes. Activation of Indian Hedgehog with purmorphamine reversed the protective effects of 2-APB on SNP-induced chondrocyte apoptosis. Blockage of TRPM7 with 2-APB relieved the clinical signs of AA in the rat model and reduced the arthritis score and paw swelling. Similar to findings in SNP-treated chondrocytes, 2-APB treatment increased the Bcl-2/Bax ratio and suppressed cleaved PARP, IL-6, MMP-13, ADAMTS-5, TRPM7, and Indian hedgehog expression in articular cartilage of AA rats. Our collective findings suggest that blockade of TRPM7 could effectively reduce chondrocyte apoptosis and articular cartilage damage in rats with adjuvant arthritis through regulation of the Indian Hedgehog signaling pathway.

Highlights

Arthritis is an acute or chronic inflammation disease that could affect multiple joints (Harth and Nielson, 2019) and cause synovial swelling, monocyte infiltration, stiffness in the joints, pannus formation and destruction of articular cartilage (Tang, 2019)
Through the analysis of MTT and Lactate Dehydrogenase (LDH), we found that the cell death rate of chondrocytes was about 50% when treated with 0.5 mM Sodium nitroprusside (SNP) for 12 h, which is consistent with previous study (Tonomura et al, 2006)
Results from immunohistochemical experiments showed increased IL-6, MMP-13, and ADAMTS-5 levels in articular cartilage of adjuvant arthritis (AA) rats that were suppressed by following 2-APB treatment (Figure7A)

Summary

Introduction

Arthritis is an acute or chronic inflammation disease that could affect multiple joints (Harth and Nielson, 2019) and cause synovial swelling, monocyte infiltration, stiffness in the joints, pannus formation and destruction of articular cartilage (Tang, 2019). Cartilage damage in arthritis is mainly the proteolytic disorder of the extracellular matrix of cartilage cells. Members of the matrix metalloprotease and metalloprotease and "A disintegrin with thrombospondin motifs" families jointly answer for cartilage catabolism (Rowan et al.,2008). Several genetic and environmental factors cause RA and chondrocyte apoptosis increase (Zhou et al, 2016). The strategy aimed at the key factors and mechanisms of regulating chondrocyte apoptosis hold promise as potential treatments for arthritis

Methods

Results

Conclusion