Hyperbaric oxygen therapy reduces the size of Leishmania amazonensis-induced soft tissue lesions in mice.

In this study we determined whether exposing mice to hyperbaric oxygen (HBO) would alter various disease parameters of a susceptible mouse strain infected with Leishmania amazonensis. BALB/c mice exposed to HBO (100% O2 at a pressure of 2.5 ATA, 1h before parasite inoculation and subsequently for 20 days) showed significant delay in lesion development and reduction in lesion parasite burdens compared with HBO-unexposed mice. Circulating levels of interferon gamma (IFN-gamma) and tumor necrosis factor (TNF-alpha) were significantly elevated in HBO-exposed as compared to HBO-unexposed mice. Concanavalin A-stimulated lymph nodes cultures from HBO-exposed mice released significantly more IFN-gamma and less interleukin 10 (IL-10) than cultures from HBO-unexposed mice, consistent with a skewed Th1 response. These results demonstrate, for the first time, that HBO can play a pathogen control role during leishmaniasis. Further studies are needed to elucidate whether hyperoxia alone or increased atmospheric pressure alone can exert a similar effect.