MiR-373 regulates inflammatory cytokine-mediated chondrocyte proliferation in osteoarthritis by targeting the P2X7 receptor.

Wei Zhang,Congfeng Luo,Yulin Zhan,Chi Zhang,Biao Zhong

doi:10.1002/2211-5463.12345

Abstract

Inflammatory cytokines commonly initiate extreme changes in the synovium and cartilage microenvironment of osteoarthritis (OA) patients, which subsequently cause cellular dysfunction, especially in chondrocytes. It has been reported that induction of the purinergic P2X7 receptor (P2X7R) can regulate the expression of a variety of inflammatory factors, including interleukin (IL)‐6 and ‐8, leading to OA pathogenesis. However, knowledge of the mechanism of upregulation of P2X7R in OA is still incomplete, and its role in chondrocyte proliferation is also not clear. It was reported previously that the expression of P2X7R was controlled by certain microRNAs, and so we tested the expression of several microRNAs and found that microRNA‐373 (miR‐373) was downregulated in the chondrocytes from OA patients. Regarding the mechanism of action, miR‐373 inhibited chondrocyte proliferation by suppressing the expression of P2X7R, as well as inflammatory factors such as IL‐6 and IL‐8. Furthermore, the proliferative and pro‐inflammatory effects of miR‐373 on the chondrocytes could be suppressed by a P2X7R antagonist, further suggesting that miR‐373 mediates chondrocyte proliferation and inflammation by targeting P2X7R. Generally, our results suggest a novel method for OA treatment by targeting the miR‐373–P2X7R pathway.

Highlights

Inflammatory cytokines commonly initiate extreme changes in the synovium and cartilage microenvironment of osteoarthritis (OA) patients, which subsequently cause cellular dysfunction, especially in chondrocytes
In P2X7R-knockout mice, was periosteal bone formation decreased in long bones without a difference in length, and osteogenesis caused by mechanical loading was Abbreviations BrdU, 5-bromo-2-deoxyuridine; IL-6/8, interleukin-6/8; KL, Kellgren–Lawrence; miR-373, microRNA-373; MTT, 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide; OA, osteoarthritis; P2X7R, purinergic P2X7 receptor; RT-PCR, real-time PCR
We found that P2X7R mRNA and protein levels were reduced by the miR-373 precursor, whereas they were increased by miR-373 inhibition (Fig. 2E,F), which suggested that miR-373 might reduce the P2X7R protein level to further affect chondrocyte proliferation and the concentrations of inflammatory factors

Summary

Introduction

Inflammatory cytokines commonly initiate extreme changes in the synovium and cartilage microenvironment of osteoarthritis (OA) patients, which subsequently cause cellular dysfunction, especially in chondrocytes. It has been reported that induction of the purinergic P2X7 receptor (P2X7R) can regulate the expression of a variety of inflammatory factors, including interleukin (IL)-6 and -8, leading to OA pathogenesis. Regarding the mechanism of action, miR-373 inhibited chondrocyte proliferation by suppressing the expression of P2X7R, as well as inflammatory factors such as IL-6 and IL-8. Affected by a variety of inflammatory factors, including interleukin (IL)-6 and IL-8, the chondrocyte and cartilage microenvironment undergoes alterations in OA patients that subsequently contributes to cell dysfunction [7]. In P2X7R-knockout mice, was periosteal bone formation decreased in long bones without a difference in length, and osteogenesis caused by mechanical loading was Abbreviations BrdU, 5-bromo-2-deoxyuridine; IL-6/8, interleukin-6/8; KL, Kellgren–Lawrence; miR-373, microRNA-373; MTT, 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide; OA, osteoarthritis; P2X7R, purinergic P2X7 receptor; RT-PCR, real-time PCR. The MiRDB database predicted that miR373 would bind with the P2X7R 30UTR and suppress the inflammation in OA [8], but further studies are required to discover their association and function in chondrocyte proliferation and inflammation

Methods

Results

Discussion

Conclusion