Photobiomodulation reduces abdominal adipose tissue inflammatory infiltrate of diet-induced obese and hyperglycemic mice.

Systemic inflammation is closely related to the development of insulin resistance and type-2 diabetes, since the activation of pro-inflammatory pathways leads to inhibition of insulin signaling. Although photobiomodulation (PBM) has proven beneficial effects on the treatment of inflammatory disorders, the phototherapeutic approach to manage the chronic inflammatory component of obesity and hyperglycemia had never been explored. In this work, obese and hyperglycemic mice are treated with PBM, and their body mass, glycemia and inflammatory infiltrate of abdominal adipose tissue are evaluated. During four weeks, irradiated animals are exposed to six irradiation sessions using an 843 nm LED (5.7 J cm at 19 mW cm per session). Non-irradiated control animals display inflammatory areas almost five times greater than the treated group (p < 0.001). This result on inflammatory infiltrate may have caused impacts on the significant lower blood glucose level from irradiated animals (p = 0.04), twenty-four hours after the last irradiation session. PBM on obese and hyperglycemic mice reduced five times the areas of inflammatory infiltrate within abdominal adipose tissue (a, b), whereas dense inflammatory regions were a common finding amidst non-irradiated animals (c). The asterisks on (c) correspond to the inflammatory infiltrate permeating adipocytes.