TLR4 stimulation and corticosteroid interactively induce osteonecrosis of the femoral head in rat

We previously reported that a toll‐like receptor 4 signaling contributes to the development of osteonecrosis of the femoral head. Also, oxidative stress is suggested to be one of the possible pathogenesis of osteonecrosis of the femoral head. A recent study showed that toll‐like receptor 4 signaling leads to oxidative stress. The aim of the present study was to evaluate whether toll‐like receptor 4 stimulation and subsequent corticosteroid treatment lead to the development of osteonecrosis of the femoral head in rat, and oxidative stress is associated with it. Male Wistar rats were randomly divided into four treatment groups: Saline + Saline, Saline + Methylprednisolone, Lipopolysaccharide + Saline, Lipopolysaccharide + Methylprednisolone. Osteonecrosis of the femoral head at 14 days after the treatment was observed in 1 of 10 Lipopolysaccharide + Saline, and 5 of 10 Lipopolysaccharide + Methylprednisolone treated rats. However, it was not observed at all in the Saline + Saline and Saline + Methylprednisolone treated groups. Glutathione peroxidase activity in the liver at 1 day after the treatment was significantly increased when treated with lipopolysaccharide. However, methylprednisolone treatment reduced the activity. On the other hand, glutathione peroxidase activity in the femur did not change in any intergroup. In conclusion, the present study showed that toll‐like receptor 4 stimulation by lipopolysaccharide administration strengthen incidence of corticosteroid‐induced osteonecrosis of the femoral head, however, concomitant oxidative stress via toll‐like receptor 4 signaling may not contribute to the development of osteonecrosis of the femoral head in rats. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:342–345, 2016.