Blood transcriptional profiles distinguish different clinical stages of cutaneous leishmaniasis in humans

Cutaneous leishmaniasis (CL) is prevalent in many low-income countries. Although CL is considered non-fatal, it has a major impact on public health systems of affected nations, causing social and economic problems due to disfiguration, morbidity, loss of productivity and medical costs for the public sector. Since no effective human vaccine against CL exists, it is crucial to understand better factors that may affect the outcome of the disease, including the impact of the pathogen on the host immune system. While transcriptomics analyses of the skin lesion in CL patients were recently reported, there is a dearth of information on the expression of immune-related genes in the blood of CL patients. We herein sought to profile the expression of immune-related genes in the blood of healed, asymptomatic and active CL patients. Using a dual-color reverse-transcription multiplex ligation-dependent probe amplification (dcRT-MLPA) assay, the transcriptomic profile of innate, adaptive and inflammatory immune-related genes in whole blood PAXgene samples obtained from two Leishmania tropica endemic areas were investigated. The blood samples were obtained from healthy individuals with positive leishmanin skin test, but without history of CL lesions (i.e., asymptomatic), and those with cured previous CL lesions (i.e., healed). We also investigated the same profile in individuals with active lesions (i.e., patients) and healthy residents of endemic areas with no history of CL and with a negative leishmanin skin test.