Modulating Inflammation and Enhancing Cell Viability: A Study on 980 nm and 660 nm Laser Irradiation in Synovial Cells.

Introduction: Photobiomodulation (PBM) is a non-invasive approach known to influence cellular activity and reduce inflammation. This study investigated the comparative effects of 980 nm and 660 nm PBM on human synovial cells (K4IM), focusing on cell viability and the expression of inflammatory mediators within the TRPV4/PI3K/AKT/mTOR signaling pathway. Methods: Human synovial cells were irradiated with 980 nm or 660 nm lasers for 30, 60, or 75 seconds using a PIoon device (continuous wave, 500 mW, 1 cm2). Cell viability was measured using the MTT assay. Gene expression levels of TRPV4, PI3K, AKT, mTOR, IL6, IL8, and IL10 were quantified via Real-Time PCR following RNA extraction and cDNA synthesis using commercial kits. Statistical analyses were performed using SPSS 22 and Excel 2021. Results: Both wavelengths significantly enhanced cell viability, with the strongest effect observed at 60 seconds (P<0.001). A slight, non-significant increase occurred at 30 seconds, while 75 seconds produced a marked improvement compared to 30 seconds (P<0.001). PBM at both wavelengths upregulated TRPV4, PI3K, AKT, mTOR, IL8, and IL10, while downregulating IL6. AKT expression was significantly elevated across all treated groups (P<0.0001). The 660 nm wavelength demonstrated comparable efficacy to 980 nm. Conclusion: PBM at 660 nm and 980 nm enhances synovial cell viability and modulates inflammation through activation of the TRPV4/PI3K/AKT/mTOR pathway. These findings highlight the importance of wavelength and exposure duration in optimizing PBM therapeutic protocols.