LED irradiation at 630 nm alleviates collagen-induced arthritis in mice by inhibition of NF-κB-mediated MMPs production.

Matrix metallopreteinase (MMP), a family of matrix degrading enzyme, plays a significant role in persistent and irreversible joint damage in rheumatoid arthritis (RA). Photobiomodulatory therapy (PBMT) has become an emerging adjunct therapy for RA. However, the molecular mechanism of PBMT on RA remains unclear. The purpose of this study is to explore the effect of 630 nm light emitting diode (LED) irradiation on RA and its underly molecular mechanism. Arthritis clinic scores, histology analysis and micro-CT results show that 630 nm LED irradiation ameliorates collagen-induced arthritis (CIA) in mice with the reduction of the extents of paw swelling, inflammation and bone damage. 630 nm LED irradiation significantly reduces MMP-3 and MMP-9 levels and inhibits p65 phosphorylation level in the paws of CIA mice. Moreover, 630 nm LED irradiation significantly inhibits the mRNA and protein levels of MMP-3 and MMP-9 in TNF-α-treated MH7A cells, a human synovial cell line. Importantly, 630 nm LED irradiation reduces TNF-α-induced the phosphorylated level of p65 but not alters STAT1, STAT3, Erk1/2, JNK and p38 phosphorylation levels. Immunofluorescence result showed that 630 nm LED irradiation blocks p65 nuclear translocation in MH7A cells. In addition, other MMPs mRNA regulated by NF-κB were also significantly inhibited by LED irradiation in vivo and in vitro. These results indicates that 630 nm LED irradiation reduces the MMPs levels to ameliorate the development of RA by inhibiting the phosphorylation of p65 selectively, suggesting that 630 nm LED irradiation may be a beneficial adjunct therapy for RA.Graphical abstract.