Therapeutic effects of a femtosecond laser on rheumatoid arthritis in rats: Attenuation of oxidative stress and inflammation

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder characterized by joint damage and persistent pain. Despite advances in treatment, there is currently no definitive cure for RA, and the side effects of available medications often limit their long-term use. Therefore, this study investigated the therapeutic potential of femtosecond laser irradiation (FSL) in treating arthritis induced by complete Freund's adjuvant (CFA) in a rat model. Twenty-four adult male Wistar rats were divided into four groups. Groups 1 and 2 served, respectively, as the negative control and positive FSL irradiated group (at a wavelength of 830 nm, a power of 200 mW, an exposure time of 120 s, a beam area of 0.8 cm² (0.5 cm radius), a power density of 0.25 W/cm², and an energy dose of 30 J/cm²). Group 3 represented the arthritic group that received a single subcutaneous injection of 0.1 ml CFA. Group 4 was the arthritic rats irradiated with FSL (two sessions/week) for three weeks. Morphological changes including edema and swelling that increased the circumference of the right hind paw, as well as histological alterations marked by cellular infiltration, synovitis, and cartilage degeneration confirmed RA in the ankle joints. These changes correlated with elevated levels of rheumatoid factor (RF), TNF-α, and IL-6, and augmented oxidative stress associated with a declined antioxidant defense system. Exposure to FSL ameliorated the morphological and histopathological changes in the ankle joint, decreased RF, TNF-α, IL-6, and MDA, and increased GSH and GPx. In conclusion, femtosecond laser irradiation showed antioxidant and anti-inflammatory properties and exerted regenerative effects on the histological features of the ankle in a rheumatoid arthritis rat model.