Effect of running exercise on titanium dioxide (TiO2)-induced chronic arthritis and sarcopenia in mice. A titanium prosthesis loosening injury model study

Abstract

Aims: This study aimed to investigate if titanium dioxide (TiO₂) joint administration is a useful pre-clinical model to study sarcopenia-related chronic arthritis, and if exercise is a useful therapeutic approach against the pathogenesis of TiO₂-induced arthritis and sarcopenia in mice.

Main methods: Two experiments were conducted. Firstly, 36 female Swiss mice were randomly divided into a control group (n = 12) and two groups who received intra-articular TiO₂ injections of 0.3-mg (n = 12) and 3-mg (n = 12), respectively. Mice were euthanized 4 and 8 weeks after TiO₂ injections. Based on data of the first experiment, mice were exposed to four groups: control (C, n = 10), exercised (Ex, n = 10), injected with 3-mg of TiO₂ (TiO₂, n = 10), and injected with 3-mg of TiO₂ and exercised (TiO₂ + Ex, n = 10) for a total of 8-weeks.

Key findings: Eight-week of 3 mg of TiO₂ joint administration promoted characteristics of chronic inflammation such as elevated histopathological score, inflammation, edema and pain. Hallmarks of sarcopenia were also observed such as muscle atrophy and loss of strength. Furthermore, voluntary exercise running reduced TiO₂-induced chronic inflammation and pain, attenuating chronic arthritis-related muscle atrophy, strength loss and impairment of locomotion capacity. In addition, exercise was also able to prevent TiO₂-induced collagen degradation, an important marker of functional and structural integrity loss of cartilage and chronic arthritis disease progression.

Significance: TiO₂ joint administration mimed titanium prosthesis release-induced joint chronic arthritis and sarcopenia-related chronic arthritis, disturbances that were attenuated by voluntary exercise.

Keywords: Arthroplasty; Inflammatory pain; Muscle atrophy; Physical activity; Strength loss.