In vitro effects of dual wavelength photobiomodulation on monocytic response in painful temporomandibular disorder

Temporomandibular disorders (TMD) are a prevalent source of chronic pain and disability, yet current therapies often provide limited relief with notable side effects. Photobiomodulation (PBM) has emerged as a promising non-pharmacologic approach to modulate inflammation and pain. This study investigated the effects of a dual-wavelength PBM protocol (laser + light-emitting diode (LED)) on the lipopolysaccharide (LPS)-stimulated monocyte response from individuals with painful TMD. Monocytes were isolated from 16 individuals with TMD enrolled in a randomized, placebo-controlled clinical trial (NCT05916235). Cells were plated into 96-well plates and divided into Control, LPS, and LPS + PBM treatment groups. Monocytes received four alternating-day treatments with two PBM probes: a laser probe (810/660 nm, 180 J/cm²) and an LED probe (660/850 nm). Cytokine and chemokine levels in culture supernatants were measured via multiplexed immunoassays. To verify cell viability after PBM treatment, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used. Statistical analysis was conducted using one-way analysis of variance (ANOVA) with Bonferroni correction, and <i>p</i> < 0.05 was considered significant. PBM significantly reduced levels of pro-inflammatory mediators interleukin-1 beta (IL-1β) (<i>p</i> = 0.005), C-X-C motif chemokine ligand 9 (CXCL9) (<i>p</i> = 0.0042), interferon gamma-induced protein 10 (IP-10) (<i>p</i> = 0.001), and tumor necrosis factor-alpha (TNF-α) (<i>p</i> = 0.0003), while increasing expression of regulatory mediators interleukin-10 (IL-10) (<i>p</i> = 0.0009), interleukin-1 receptor antagonist (IL-1RA) (<i>p</i> = 0.004), and CC motif chemokine ligand 17 (CCL17) (<i>p</i> = 0.003).These findings suggest that the dual-wavelength PBM protocol was able to shift the monocyte immune response from a more pro-inflammatory (M1) phenotype to a more anti-inflammatory, tissue-repair (M2) cytokine profile. These results provide additional evidence for PBM as a benign and non-invasive technique to control and potentially modify TMD-related inflammation. ClinicalTrials.gov ID: NCT05916235.