Photobiomodulation (PBM) therapy has been effectively used to relieve pain and inflammation and promote tissue healing and regeneration in a broad range of ailments. Prior work has focused on intracellular mitochondrial cytochrome c oxidase, while extracellular latent TGF-β1 activation had been noted. This work investigated the role of PBM-generated redox signaling and integration in normal oral keratinocytes, using Western blots and pathway-specific small molecule inhibitors. We observed that PBM primarily generates ROS intracellularly within mitochondria, which then diffuse extracellularly to activate latent TGF-β1. This activation triggers ATF-4 expression through both canonical (Smad3) and non-canonical (p38, ERK) TGF-β signaling pathways. We observed a critical role for NFκB as an essential integrator, coordinating these responses as evidenced by the loss of ATF-4 expression following NFκB inhibition (BAY II) after both PBM and TGF-β1 treatments. Proteomic pathway analysis revealed that PBM downregulates inflammatory and apoptotic pathways while activating stress-adaptive responses in the NFκB pathway. A core set of PBM-induced redox, NFκB, and TGF-β signaling targets was identified. These findings suggest that optimal PBM treatment responses require a coordinated action of multiple signaling pathways that optimize cellular adaptation to stress and promote tissue repair rather than protracted inflammation and cell death.

Bothrops jararacussu (BjsuV) snake bites cause severe local and systemic effects leading to muscle damage and amputation that cannot be prevented by antivenom alone. The anti-inflammatory effects of Photobiomodulation (PBM) has been noted to reduce muscle damage and promote tissue regeneration. This study investigated the mechanism of PBM in modulating macrophage functions via TGF-β1 singlaing. Macrophages were evaluated after treatments with BjsuV , TGF-β1, TGF-β inhibitor - SB431542, and PBM with 660 nm red or 810 nm near-infrared laser at 10 mW/cm ² , 400 and 500s, 4 J/cm ² and 5 J/cm ² , 7.5 p.J/cm ² , 1.7ɇ). BjsuV significantly reduced macrophage survival and migration, but increased phagocytosis. Treatment with PBM significantly counteracted these venom-induced inflammatory responses. Recombinant TGF-β1 treatments stimulated migration and reduced phagocytosis while preincubation with SB431542 only partially neutralized PBM responses. These observations indicate the anti-inflammatory effects of PBM in macrophages contribute to its therapeutic potential in mitigating venom-induced multiple signaling pathways.