Effects of photobiomodulation, alone or combined with dexamethasone, on cellular metabolic activity and inflammatory markers in LPS/IFN-γ-stimulated J774 macrophages

The aim of the present study was to investigate the effects of photobiomodulation (PBM), dexamethasone (DEXA), and their combination on cellular metabolic activity and inflammatory cytokines in LPS/IFN-γ-stimulated J774 macrophages.Cells were stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) and treated with PBM (780 nm) and/or DEXA (2 or 4 μM). Cellmorphology, metabolic activity assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and total protein, tumornecrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) levels measured by enzyme-linked immunosorbent assay (ELISA) were analyzed at 24 and 48hours. PBM combined with DEXA at 2 μM increased MTT metabolic activity at 24 hours and was associated with preserved morphology and maintainedhigher total protein levels, with consistent superiority over DEXA alone. PBM + DEXA 2 μM produced the strongest reduction in TNF-α and IL-6 at 24hours, and IL-6 levels remained lower at 48 hours compared to the M1 + PBM group. The 4 μM dose demonstrated lower efficacy and signs of functionalimpairment, which were partially mitigated by PBM. These findings indicate that PBM may enhance the anti-inflammatory effects of low-dose DEXA while supporting a favorable cellular metabolic response, suggesting its potential as an adjunct strategy to optimize the glucocorticoid-based modulation ofinflammatory responses.