Immune profile of the nasal mucosa in patients with cutaneous leishmaniasis.

Localized skin lesions are characteristic of cutaneous leishmaniasis (CL); however, Leishmania (Viannia) species, responsible for most CL cases in the Americas, can spread systemically sometimes resulting in mucosal disease. Detection of Leishmania has been documented in healthy mucosal tissues (conjunctiva, tonsils, and nasal mucosa) and healthy skin of CL patients and in individuals with asymptomatic infection in endemic areas of L. (V.) panamensis and L. (V.) braziliensis transmission. However, the conditions and mechanisms that favor parasite persistence in healthy mucosal tissues are unknown. In this descriptive study we compared the cell populations of the nasal mucosa (NM) of healthy donors and patients with active CL, and explored immune gene expression signatures related with molecular detection of Leishmania in this tissue, in the absence of clinical signs or symptoms of mucosal disease. The cellular composition and gene expression profiles of NM samples from active CL patients were similar to those of healthy volunteers, with a predominance of epithelial over immune cells, and within the CD45+ cell population, a higher frequency of CD66b+ followed by CD14+ and CD3+ cells. In CL patients with molecular evidence of Leishmania persistence in the NM, genes characteristic of an anti-inflammatory and tissue repair responses (IL4R, IL5RA, POSTN and SATB1) were over-expressed relative to NM samples from CL patients in which Leishmania was not detected. Here, we report the first immunological description of subclinically infected NM tissues of CL patients, and provide evidence of a local anti-inflammatory environment favoring parasite persistence in the NM.