Treating metabolic syndrome’s metaflammation with low level light therapy: preliminary results

Metabolic syndrome comprises a constellation of morbidities such as insulin resistance, hyperinsulinemia, atherogenic dyslipidemia, dysglycemia and obesity (especially abdominal). Metabolic alterations are observed in major insulin target organs, increasing the risk of cardiovascular diseases, type-2 diabetes and therefore mortality. Tissue alterations are characterized by immune cells infiltrates (especially activated macrophages). Released inflammatory mediators such as TNF-α induce chronic inflammation in subjects with metabolic syndrome, since inflammatory pathways are activated in the neighboring cells. The intra-abdominal adipose tissue appears to be of particular importance in the onset of the inflammatory state, and strategies contributing to modulate the inflammatory process within this adipose tissue can mitigate the metabolic syndrome consequences. Considering the low level light therapy (LLLT) recognized benefits in inflammatory conditions, we hypothesized this therapeutic approach could promote positive effects in modulating the inflammatory state of metabolic syndrome. That being the scope of this study, male C57BL/6 mice were submitted to a high-fat/high-fructose diet among 8 weeks to induce metabolic syndrome. Animals were then irradiated on the abdominal region during 21 days using an 850 nm LED (6 sessions, 300 seconds per session, 60 mW output power, ~6 J/cm2 fluence, ~19 mW/cm2 fluence rate). Before and during treatment, blood was sampled either from the retroorbital plexus or from tail puncture for glucose, total cholesterol and triglycerides analysis. So far our results indicate no alterations on these metabolic parameters after LLLT. For further investigations, blood was collected for plasma inflammatory cytokine quantification and fresh ex vivo samples of liver and intra-abdominal adipose tissue were harvested for immunohistochemistry purposes.