High-Frequency Near-Infrared Diode Laser Irradiation Attenuates IL-1β-Induced Expression of Inflammatory Cytokines and Matrix Metalloproteinases in Human Primary Chondrocytes

High-frequency near-infrared diode laser provides a high-peak output, low-heat accumulation, and efficient biostimulation. Although these characteristics are considered suitable for osteoarthritis (OA) treatment, the effect of high-frequency near-infrared diode laser irradiation in in vitro or in vivo OA models has not yet been reported. Therefore, we aimed to assess the biological effects of high-frequency near-infrared diode laser irradiation on IL-1β-induced chondrocyte inflammation in an in vitro OA model. Normal Human Articular Chondrocyte-Knee (NHAC-Kn) cells were stimulated with human recombinant IL-1β and irradiated with a high-frequency near-infrared diode laser (910 nm, 4 or 8 J/cm(2)). The mRNA and protein expression of relevant inflammation- and cartilage destruction-related proteins was analyzed. Interleukin (IL) -1β treatment significantly increased the mRNA levels of IL-1β, IL-6, tumor necrosis factor (TNF) -α, matrix metalloproteinases (MMP) -1, MMP-3, and MMP-13. High-frequency near-infrared diode laser irradiation significantly reduced the IL-1β-induced expression of IL-1β, IL-6, TNF-α, MMP-1, and MMP-3. Similarly, high-frequency near-infrared diode laser irradiation decreased the IL-1β-induced increase in protein expression and secreted levels of MMP-1 and MMP-3. These results highlight the therapeutic potential of high-frequency near-infrared diode laser irradiation in OA.