IL-32γ promotes the healing of murine cutaneous lesions caused by Leishmania braziliensis infection in contrast to Leishmania amazonensis

Abstract

Background: Interleukin 32 (IL-32) is a pro-inflammatory cytokine induced in patients with American tegumentary leishmaniasis (ATL) caused by Leishmania braziliensis. Here, we investigated whether IL-32 is also expressed in patient lesions caused by L. amazonensis. In addition, we evaluated experimental L. amazonensis and L. braziliensis infections in C57BL/6 transgenic mice for human IL-32γ (IL-32γTg) in comparison with wild-type (WT) mice that do not express the IL-32 gene. Results: Human cutaneous lesions caused by L. amazonensis express higher levels of IL-32 than healthy control skin. In mice, the presence of IL-32γ promoted the control of cutaneous lesions caused by L. braziliensis, but not lesions caused by L. amazonensis in an ear dermis infection model. In addition, IL-32γTg mice displayed less tissue parasitism and inflammation in IL-32γTg than WT mice during the healing phase of L. braziliensis infection. Production of antigen-specific pro-inflammatory cytokines was higher in IL-32γTg mice than in WT mice during L. braziliensis infection but not during L. amazonensis infection. Conclusions: Human cutaneous lesions caused by L. amazonensis express high levels of IL-32. In mice, the presence of IL-32γ contributes to the lesion healing caused by L. braziliensis but not by L. amazonensis. Data suggest that despite the ability for both species to induce IL-32 in humans, the connections between this cytokine and other immune players induced by related species of parasites can lead to distinct outcomes of the murine infections.