N -(2-Hydroxyphenyl)acetamide: a Novel Suppressor of RANK/RANKL Pathway in Collagen-Induced Arthritis Model in Rats

Abstract

RANKL and RANK are potential contributors of inflammatory cascade in human and animal model of arthritis. The current study aims to investigate the effect of N-(2-hydroxyphenyl)acetamide (NA-2) on regulation of RANKL pathway in collagen-induced arthritis (CIA) model in rats. CIA was induced using bovine type II collagen in female Wistar rats. The clinical parameters, level of pro-inflammatory and oxidative stress markers were measured to determine the progression of the disease. The mRNA level of RANKL and RANK and downstream mediators of inflammation i.e. c-fos, c-jun, NF-κB and Akt were analysed in spleen tissue using real-time PCR. Immunohistochemical analysis of iNOS, pAkt and c-Fos was also done in spleen tissue. Treatment with NA-2 and indomethacin showed increase in body weight and significant reduction in paw volume and arthritic score (p < 0.0001). Marked reduction in the level of oxidative stress markers, NO, PO and GSH (p < 0.0001), and pro-inflammatory markers, IL-1β (p < 0.0001) and TNF-α (p < 0.01), was also observed. Likewise, NA-2 and indomethacin treatment also significantly suppressed the mRNA expression of RANKL, RANK, c-fos, c-jun, NF-κB (p < 0.0001) and Akt (p < 0.01) and protein expression of iNOS, pAkt and c-Fos (p < 0.0001) compared to the arthritic control group. Our findings suggest that NA-2 is an antiarthritic agent acting in a pleiotropic manner in CIA rats by not only reducing the clinical signs of arthritis, inflammatory cytokines and free radical production but also attenuating the RANK/RANKL signaling pathway.

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