Effects of red light-emitting diode therapy in imiquimod-induced psoriasis in mice.

Abstract

Growing evidence supports the therapeutic potential of phototherapies, particularly light-emitting diodes (LEDs), in modulating inflammation and restoring tissue homeostasis. Here, we evaluated the effects of red LED irradiation (660&#xa0;nm) in a murine model of psoriasis induced by imiquimod (IMQ). C57BL/6 mice were treated with IMQ for 12 consecutive days and exposed to LED on alternate days from day 4, totalling five sessions. Macroscopic evaluation showed a significant reduction in skin-fold thickness and Psoriasis Area and Severity Index (PASI) scores in LED-treated mice. Histological analyses confirmed that IMQ induced epidermal thickening, erythema, mast cell infiltration, and collagen alterations. LED exposure attenuated epidermal changes (p&#xa0;<&#xa0;0.0001, IMQ&#xa0;+&#xa0;LED versus IMQ), reduced mast cell numbers (p&#xa0;<&#xa0;0.05, IMQ&#xa0;+&#xa0;LED versus IMQ), and modulated collagen fiber distribution, although it did not reverse dermal thickening. At the systemic level, IMQ increased spleen weight and white pulp expansion, effects not prevented by LED. In skin samples, IMQ markedly elevated interleukin (IL)-1&#x3b2; and tumor necrosis factor (TNF)-&#x3b1; levels, which were significantly reduced by LED treatment (p&#xa0;<&#xa0;0.05). In plasma, IL-22 was elevated in IMQ-treated animals but decreased in the IMQ&#xa0;+&#xa0;LED group (p&#xa0;<&#xa0;0.05), while no significant changes were detected for IL-1&#x3b2;, IL-17A, IL-23, TNF-&#x3b1;, or macrophage inflammatory protein (MIP)-3&#x3b1;. Together, these results suggest that red LED phototherapy reduces clinical severity and partially modulates both local and systemic inflammation in IMQ-induced psoriasis, supporting its potential as a complementary therapeutic approach.