Proinflammatory M1 Macrophages On Apoptosis.

XIST[LncRNA]

miR-376c-5p[miRNA]

OPN[mRNA]

THP-1 monocytic cell line

Homo sapiens (human)

J Cell Physiol 2020 Jan 235, 281-293 doi:10.1002/jcp.28968 PMID:31215024

XIST/miR-376c-5p/OPN axis modulates the influence of proinflammatory M1 macrophages on osteoarthritis chondrocyte apoptosis.

Luciferase reporter assay etc.

In the present study, we reveal that the overexpression of osteopontin (OPN), a cytokine, and a matrix protein involved in arthritis and chondrocyte apoptosis in OA, could exacerbate the inflammatory microenvironment in OA via promoting the production of proinflammation cytokines and the levels of degradative enzymes in M1 macrophages, therefore, enhancing the cytotoxicity of M1 macrophage on chondrocytes. XIST expression significantly increases in OA tissue specimens. XIST serves as a competing endogenous RNA for miR-376c-5p to compete with OPN for miR-376c-5p binding, thus counteracting miR-376c-5p-mediated OPN suppression. XIST knockdown could improve the inflammatory microenvironment in OA via acting on M1 macrophages, subsequently affecting the apoptosis of cocultured chondrocytes. miR-376c-5p inhibition exerts an opposing effect on M1 macrophages and cocultured chondrocytes, as well as significantly reverses the effect of XIST knockdown. As a further confirmation, XIST and OPN mRNA expression significantly increased in OA tissues and was positively correlated in tissue samples. In summary, we provide a novel mechanism of macrophages and the inflammatory microenvironment affecting chondrocyte apoptosis. XIST and OPN might be potential targets for OA treatment, which needs further in vivo experimental