Efeito da laserterapia de baixa potência na paracoccidioidomicose experimental murina: caracterização do exsudato celular e do perfil de citocinas

Abstract

Innate immunity is an important component of host defense against fungi, and in this context machophages and neutrophils (PMN) play a central role in paracoccidioidomycosis. The treatment of this disease includes the use of antifungals, which in addition to the prolonged administration time needed may cause many side effects. Low level laser therapy (LLLT) has been used as an adjuvant treatment for many ailments and its modulating effect on neutrophils has already been demonstrated; however it is necessary to better understand the mechanisms involved in this process. In this work, we evaluated the effects of LLLT applied ―in vivo‖ at the hind paws in mice, aiming the bone marrow. These mice were infected in the subcutaneous air pouch with Pb18 or Pb265 P. brasiliensis isolates. Unirradiated animals were used as controls. After 8 days of infection the cells of air pouch were collected and analyzed for the number, protein concentration and release of ROS, mitochondrial activity of PMN and migration profile and secretion of cytokines (GM-CSF, IFN-γ, IL-12, IL- 4, IL-10 and IL-17) by the cells present in the exudate. LLLT-treated animals showed increased mitochondrial activity, protein content and release of ROS by PMN and in the number of cells and decreased the secretion of IL-10 exudate cells obtained after inoculation with the virulent strain Pb18. In turn, the infection with the low virulence strain Pb265 also led to an increase in mitochondrial activity, but there was a decrease in protein concentration and the release of ROS was similar to that of the unirradiated controls.. No differences were observed in the secretion of the GM-CSF, IFN-γ, IL-12, IL-4 and IL-17 cytokines by exudate cells stimulated by any of the strains. Regarding cell migration, PMN are the main cell type found at the inoculum site, followed by lymphocytes and monocytes. The number of PMN was decreased in the treatment with LLLT when the stimulus was Pb18 and increased when it was Pb265. For the lymphocytes the reverse occurred, in the group stimulated with Pb18 the laser acted increasing this cellular type, and decreasing when the stimulus was the Pb265. For monocytes, there was no change when the stimulus was Pb18 and there was a decrease when the stimulus was Pb265 in the group treated with LLLT. The results suggest that treatment with LLLT elicits a fungicidal activity to the PMN and higher resolution of the infection caused by the virulent Pb18 strain.