Cutaneous leishmaniasis is a localized infection controlled by CD4+ T cells that produce IFN-γ within lesions. Phagocytic cells recruited to lesions, such as monocytes, are then exposed to IFN-γ which triggers their ability to kill the intracellular parasites. Consistent with this, transcriptional analysis of patient lesions identified an interferon stimulated gene (ISG) signature. To determine whether localized L. braziliensis infection triggers a systemic immune response that may influence the disease, we performed RNA sequencing (RNA-seq) on the blood of L. braziliensis-infected patients and healthy controls. Functional enrichment analysis identified an ISG signature as the dominant transcriptional response in the blood of patients. This ISG signature was associated with an increase in monocyte- and macrophage-specific marker genes in the blood and elevated serum levels IFN-γ. A cytotoxicity signature, which is a dominant feature in the lesions, was also observed in the blood and correlated with an increased abundance of cytolytic cells. Thus, two transcriptional signatures present in lesions were found systemically, although with a substantially reduced number of differentially expressed genes (DEGs). Finally, we found that the number of DEGs and ISGs in leishmaniasis was similar to tuberculosis–another localized infection–but significantly less than observed in malaria. In contrast, the cytolytic signature and increased cytolytic cell abundance was not found in tuberculosis or malaria. Our results indicate that systemic signatures can reflect what is occurring in leishmanial lesions. Furthermore, the presence of an ISG signature in blood monocytes and macrophages suggests a mechanism to limit systemic spread of the parasite, as well as enhance parasite control by pre-activating cells prior to lesion entry.

Background Cutaneous leishmaniasis (CL), caused by Leishmania braziliensis , is the most important presentation of tegumentary leishmaniasis (TL) in Latin American. While the role of dogs as reservoirs of Leishmania infantum , and the clinic features of canine visceral leishmanisis are well described, little is known about the importance of dogs in the transmission of L . braziliensis to humans. In the present study, we determine the frequency of L . braziliensis infection in dogs with cutaneous and mucosal ulcers in an endemic area of CL. We also describe the clinical manifestations and histopathologic features, and determine if the parasites isolated from dogs are genetically similar to those found in humans. Methodology This is a cross sectional study in which 61 dogs living in an endemic area of CL and presenting ulcerated lesions were evaluated. Detection of L . braziliensis DNA by polymerase chain reaction (PCR) in skin biopsies, serology and leishmania skin test (LST) with soluble L . braziliensis antigen were performed. The clinical and histopathologic features were described, and we compared the genotypic characteristics of isolates obtained from dogs and humans. Principal findings The sensitivity of the three tests together to detect exposure was 89% and the concordance between the tests was high. The skin lesions were most frequent in the ears, followed by scrotal sac. The PCR was positive in 41 (67%) of animals, and the lesions in the snout, followed by the scrotal sac and ears were the sites where parasite DNA was most detected. There were genotype s imilarities between L . braziliensis isolates from dogs and humans. Conclusions The high frequency of L . braziliensis infection in dogs with ulcers and the similarities between the isolates of L . braziliensis and cutaneous leishmaniasis in dogs and humans in an endemic area of TL, raise the possibility of an important role of dogs in the transmission chain of L . braziliensis .

Background Cutaneous leishmaniasis (CL) caused by L. braziliensis is characterized by a single ulcer or multiple cutaneous lesions with raised borders. Cure rates below 60% are observed in response to meglumine antimoniate therapy. We investigated the impact of obesity on CL clinical presentation and therapeutic response. Methods A total of 90 age-matched CL patients were included (30 obese, 30 overweight and 30 with normal BMI). CL was diagnosed through documentation of L. braziliensis DNA by PCR or identification of amastigotes in biopsied skin lesion samples. Serum cytokine levels were determined by chemiluminescence. Antimony therapy with Glucantime (20mg/kg/day) was administered for 20 days. Results Obese CL patients may present hypertrophic ulcers rather than typical oval, ulcerated lesions. A direct correlation between BMI and healing time was noted. After one course of Antimony, cure was achieved in 73% of patients with normal BMI, 37% of overweight subjects, yet just 18% of obese CL patients (p<0.01). Obese CL cases additionally presented higher leptin levels than overweight patients or those with normal BMI (p<0.05). Conclusions Obesity modifies the clinical presentation of CL and host immune response, and is associated with greater failure to therapy.