Photobiomodulation (PBM) regulates nitric oxide (NO) production by peripheral blood mononuclear cells (PBMC) isolated from Multiple Sclerosis (MS) patients

Abstract Multiple sclerosis (MS) is an autoimmune disease characterized by myelin destruction, neurodegeneration and mitochondrial dysfunction. High production of nitric oxide (NO) by iNOS contributes to the generation of reactive nitrogen species, leading to increased nitrosative stress and mitochondrial dysfunction linked to MS progression. Current therapies focus on the suppression of the immune system in early stages, but they are not effective in chronic stages where nitrosative stress takes control over pathogenic mechanisms. Thus, new therapies that reduce nitrosative stress and offer neuroprotection at any stage are needed. Photobiomodulation (PBM) has demonstrated efficacy to improve neurodegenerative disorders. Our lab showed that PBM at 670nm reduced clinical severity in the C57BL/6 mouse experimental autoimmune encephalomyelitis model of MS by down-regulation of nitrosative stress, apoptosis, and pro-inflammatory cytokines, and up-regulation of anti-inflammatory cytokines. Likewise, PBM modulated cytokine expression by peripheral blood mononuclear cells (PBMC) and CD4+ T cells isolated from MS patients. Here we show that PBM reduces NO production by PBMC from MS patients. PBMC were isolated by gradient centrifugation, activated with Phytohaemagglutinin (PHA) and received PBM treatment. As surrogate for NO, nitrite production in supernatants was measured by fluorometry. The most effective PBM doses at decreasing nitrite were 830nm (10J/cm2) and pulsed 640nm (3J/cm2). The expression of Interferon-γ correlated with nitrite expression at these same doses. PBM effect was dependent on the disease modifying drug that subjects were taking. The results show the potential of PBM on NO regulation in MS patients.