Since many of the currently available antileishmanial treatments exhibit toxicity, low effectiveness, and resistance, search and validation of new therapeutic targets allowing the development of innovative drugs have become a worldwide priority. This work presents a structure-based drug discovery strategy to validate the Lmj_04_BRCT domain as a novel therapeutic target in Leishmania spp. The structure of this domain was explored using homology modeling, virtual screening, and molecular dynamics studies. Candidate compounds were validated in vitro using promastigotes of Leishmania major, L. amazonensis, and L. infantum, as well as primary mouse macrophages infected with L. major. The novel inhibitor CPE2 emerged as the most active of a group of compounds against Leishmania, being able to significantly reduce the viability of promastigotes. CPE2 was also active against the intracellular forms of the parasites and significantly reduced parasite burden in murine macrophages without exhibiting toxicity in host cells. Furthermore, L. major promastigotes treated with CPE2 showed significant lower expression levels of several genes (α-tubulin, Cyclin CYCA, and Yip1) related to proliferation and treatment resistance. Our in silico and in vitro studies suggest that the Lmj_04_BRCT domain and its here disclosed inhibitors are new potential therapeutic options against leishmaniasis.

Leishmaniasis is spreading in Europe, especially in endemic countries such as Italy and Spain, in part due to ongoing climate change and the increase in travel and migration. Although Leishmania infantum is the main agent responsible for this disease in humans and animals, other species and hybrids have been detected. This highlights the need to continue isolating and characterizing Leishmania strains from biological samples of infected hosts. In this study, we characterized the recently isolated parasites L. infantum NAV and L. infantum TDL, obtained from naturally infected mammals (dogs), and we compared them with the widely distributed and studied strain L. infantum BCN 150. Both NAV and TDL promastigotes showed a slower growth rate than BCN 150 and were significantly more sensitive to amphotericin B and miltefosine. Furthermore, the expression of the CYCA gene (involved in cell cycle and proliferation) was significantly downregulated in NAV and TDL isolates. On the other hand, CYC6 (implicated in treatment resistance) and APG9 (related to the recycling of protein under stress conditions and/or while undergoing a differentiation process and treatment resistance) levels were upregulated, compared to those measured in BCN 150. Both isolates displayed a higher infection capacity (>3 amastigotes per macrophage and >70% of infected macrophages) compared to controls (<2 amastigotes/cells and <50% of infected macrophages). Finally, a higher susceptibility to miltefosine treatment was observed in intracellular NAV and TDL amastigotes. In conclusion, TDL and NAV are novel Leishmania isolates that might be useful for in vitro and in vivo assays that will allow a better understanding of the parasite biology in Mediterranean areas.

Background/Objectives: Antimicrobial peptides (AMPs) represent a promising class of therapeutics with diverse biological functions, including antibacterial, anti-fungal, anti-parasitic and anti-tumoral activities. Previous works demonstrated the successful repurposing of the two synthetic AMPs 19-2.5 and 19-4LF for cutaneous leishmaniasis, when the compounds were administered in solution on skin lesions caused by Leishmania major in a BALB/c mouse model. In this research project, we assessed the activity of 19-4LF, 19-2.5, and their hybrid 19-2.5LF derivative when formulated as a cream for topical administration in the same animal model. Methods: The peptides were formulated in DAC cream and applied to the wound of BALB/C mice for 30 days. Lesion progression was monitored using a digital caliper. Parasite burden was measured by qPCR. Parasite viability was assessed using MTT and microscopy imaging assays. Results: The three peptides in cream formulation succeeded in reducing the skin lesion. Peptide 19-4LF was the most potent, followed by 19-2.5LF and then 19-2.5. In addition, 19-4LF was able to significantly reduce the parasite burden in the skin lesions of infected mice, as measured by quantifying L. major Lm18S ribosomal gene mRNA levels using qPCR. Moreover, when combined, the peptides exhibited synergistic effects on L. major promastigotes and significantly reduced the number of amastigotes in infected macrophages. Conclusions: These studies support the approach of repurposing these AMPs as antileishmanial drugs and identify 19-4LF as a lead candidate for further studies. While historical barriers to peptide therapeutics included high production costs, recent advancements in biological fermentation and synthesis strategies have significantly improved their economic viability. Furthermore, the use of nanotechnology delivery systems can reduce the required dosage, further making peptide therapy a sustainable option for neglected diseases, including leishmaniasis.

Leishmaniasis is caused by protozoan parasites from the genus Leishmania and remains one of the major threats to global health, impacting millions of people worldwide as well as animals including dogs. Several treatments have been used for managing leishmaniasis; nevertheless, drug resistance has emerged as an important obstacle to disease control. Therefore, there is an urgent need to discover new therapeutic targets. The aim of this work was to study the role played by the breast cancer associated 1 C-terminal (BRCT) domain from LmjPES protein (Pescadillo ribosomal biogenesis factor) in Leishmania major‘s pathogenesis through the construction of novel genomic tools. For this purpose, Leishmania integrative plasmids that were able to express the BRCT domain from LmjPES and a hypothetical defective LmjPES lacking this BRCT domain were constructed. It was observed that the overexpression of the aforementioned BRCT domain in L. major dysregulated the mRNA expression of 152 genes (95 up-regulated and 57 down-regulated) in respect to control parasites. Furthermore, clustering studies of these altered genes revealed an enrichment in genes related to metabolic processes, transporter activity, response to stimuli, and protein folding, which are categories described to be associated with the metacyclogenesis process and parasite survival. Interestingly, these genes reached normal levels of expression in parasites transfected with a defective LmjPES (a mutated gene lacking the coding sequence of the BRCT domain). In addition, it was found that the footpad of mice inoculated with LmjPES BRCT-overexpressing parasites had significantly greater inflammation compared to the size of the footpad of animals infected with the control parasites. Based on all these results, it was suggested that the BRCT domain from LmjPES might play a role in L. major‘s infection process and pathogenesis.

(AR) BM15, BM18, BM29, BM36, BM39 konposatuen jarduera leishmanizidaren azterketa produkzioaren informazio-fitxa

Leishmaniasia: gaixotasun globala. Tratamendurako hautagai berriak produkzioaren informazio-fitxa