Javier Carrión

Cutaneous leishmaniosis (CL) remains a major neglected tropical disease, with current therapies constrained by toxicity, high cost, and variable efficacy. Here, we evaluated an immunochemotherapy strategy combining topical amphotericin B (AmB) with the therapeutic DNA vaccine HisAK70 in a murine model of Leishmania major infection. BALB/c mice were subcutaneously infected and treated with topical AmB cream alone, AmB plus HisAK70, or paromomycin (PM) as a reference therapy. Therapeutic efficacy was assessed through lesion progression, parasite burden in draining lymph nodes and spleen, and immunological markers associated with parasite control. Both PM and the combined AmB + HisAK70 treatment significantly reduced lesion progression and markedly decreased parasite burden compared with infected controls, demonstrating effective control of local infection and systemic dissemination. Importantly, the combination therapy enhanced the efficacy of AmB alone, supporting the beneficial contribution of vaccine-driven immune modulation to therapeutic outcome. Therapeutic efficacy was associated with reduced arginase activity in infected tissues and an increased IFN-γ/IL-4 ratio, indicative of a protective Th1-oriented immune response. Together, these findings highlight immunochemotherapy as a promising strategy for CL treatment, integrating localized topical drug delivery with targeted immune activation to improve therapeutic efficacy while potentially reducing systemic toxicity.

Cutaneous leishmaniasis (CL) remains difficult to treat because Leishmania parasites persist within dermal macrophages and suppress their microbicidal activity, promoting chronic infection. Toll‐like receptor (TLR) agonists can restore macrophage effector functions, but their therapeutic use is limited by systemic toxicity. Here, we developed a lipid‐based nanoemulsion (NE) for the systemic delivery of the TLR7 agonist gardiquimod (GDQM) to improve macrophage targeting and reduce off‐target inflammatory effects. Following intravenous administration, GDQM‐NEs efficiently accumulated in dermal lesions and significantly reduced systemic cytokine release compared with free GDQM, resulting in an improved safety profile. Importantly, nanoencapsulation preserved GDQM antileishmanial activity achieving an approximately 2‐log reduction in parasite burden. Treatment induced both Th1‐associated cytokines (IFN‐γ and IL‐12p70) and regulatory responses, including IL‐10 production and FoxP3 ⁺ regulatory T‐cell expansion. Despite efficient lesion accumulation, CD86 upregulation was detected in macrophages from draining lymph nodes (dLNs) but not at the lesion site, indicating limited local macrophage activation. These findings indicate that GDQM‐NEs effectively overcome major delivery and safety barriers associated with systemic TLR7 agonist administration, whereas the lesion microenvironment and TLR‐driven regulatory mechanisms remain key constraints on therapeutic efficacy. Combining TLR agonists with strategies that counteract these local suppressive pathways may further enhance treatment outcomes in CL.

The leishmaniases are a group of neglected tropical diseases caused by kinetoplastid protozoa of the genus Leishmania, transmitted by phlebotomine sandflies. In the absence of a human vaccine, current chemotherapeutic options remain suboptimal due to limited target selectivity, high cost, restricted availability in endemic low-resource regions, and escalating parasite resistance. This review highlights recent advances in rational drug design directed at the kinetoplast—a distinctive mitochondrial organelle critical for parasite viability. Different targets (e.g., kDNA, G-quadruplex, topoisomerases) and innovative approaches employing mitochondrion-targeted small molecules are discussed, as well as ligand-functionalized nanoparticle delivery systems that can transport bioactive agents to the parasite’s mitochondrial microenvironment. These strategies highlight the kinetoplast’s strong translational relevance as a selective antileishmanial target. By exploiting its unique molecular machinery, these strategies may offer improved parasite selectivity, although potential mitochondrial liabilities in host cells must be carefully evaluated.

Plant-derived natural products are an invaluable source of structurally diverse secondary metabolites with ecological and pharmacological significance. Geranium macrorrhizum, a species known for producing essential oils rich in monoterpenoids and sesquiterpenes, has been scarcely explored for its antiparasitic potential. This study represents the first comprehensive evaluation of the antiprotozoal activity of G. macrorrhizum obtained from cultivated plants. Plant material was produced under controlled greenhouse cultivation systems, ensuring high-quality and reproducible metabolite profiles. Essential oils were obtained through hydrodistillation and chemically characterized by Gas Chromatography-Mass Spectrometry (GC–MS). In vitro assays were conducted against Giardia duodenalis, Trichomonas gallinae, and Leishmania infantum to assess antiparasitic efficacy and cytotoxicity. The results demonstrated strong activity of essential oils against Trichomonas gallinae, and Leishmania infantum, indicating the relevance of lipophilic compounds—especially germacrone—as key bioactive constituents. Germacrone exhibited strong and selective antiparasitic activity, outperforming its structural analogues. Microscopic analyses revealed distinct parasite-specific morphological alterations, differing from those induced by conventional drugs such as metronidazole and amphotericin B. These findings highlight G. macrorrhizum obtained through biotechnological cultivation as a novel and sustainable source of natural antiprotozoal agents. The study underscores the importance of integrating controlled cultivation with phytochemical and biological evaluation to advance the discovery of innovative bioactive compounds.

Three genera of viruses of the family Totiviridae establish endosymbiotic associations with flagellated protozoa responsible for parasitic diseases of great impact in the context of One Health. Giardiavirus, Trichomonasvirus, and Leishmaniavirus infect the protozoa Giardia sp., Trichomonas vaginalis, and Leishmania sp., respectively. In the present work, we review the characteristics of the endosymbiotic relationships established, the advantages, and the consequences caused in mammalian hosts. Among the common characteristics of these double-stranded RNA viruses are that they do not integrate into the host genome, do not follow a lytic cycle, and do not cause cytopathic effects. However, in cases of endosymbiosis between Leishmaniavirus and Leishmania species from the Americas, and between Trichomonasvirus and Trichomonas vaginalis, it seems that it can alter their virulence (degree of pathogenicity). In a mammalian host, due to TLR3 activation of immune cells upon the recognition of viral RNA, uncontrolled inflammatory signaling responses are triggered, increasing pathological damage and the risk of failure of conventional standard treatment. Endosymbiosis with Giardiavirus can cause the loss of intestinal adherence of the protozoan, resulting in a benign disease. The current knowledge about viruses infecting flagellated protozoans is still fragmentary, and more research is required to unravel the intricacies of this three-way relationship. We need to develop early and effective diagnostic methods for further development in the field of translational medicine. Taking advantage of promising biotechnological advances, the aim is to develop ad hoc therapeutic strategies that focus not only on the disease-causing protozoan but also on the virus.

Leishmaniasis is a chronic global arthropod-borne zoonotic disease produced by several species of Leishmania , with cutaneous, mucocutaneous, and visceral clinical manifestations. In Spain, only Leishmania infantum has been reported so far, although other species of Leishmania , such as L. tropica and L. major , are present in surrounding countries. The aim of this work is to analyze the occurrence of Leishmania spp. infection in European wildcats ( Felis silvestris ) as sentinels, including their genotypic characterization. Necropsies of 18 road killed wildcats were conducted. Samples of ear skin and spleen were taken for DNA isolation and PCR of the highly sensitive SSUrDNA target. Subsequent PCR tests were performed using more specific targets for the determination of Leishmania species: hsp70 and ITS1 . Positive samples were sequenced, and phylogenetic trees constructed. Seven wildcats were found positive for Leishmania spp.. Based on the hsp70 and ITS1 sequences, an animal was found to be infected only with L. tropica in ear skin samples, while two cats were found to be infected with L. infantum in both the ear skin and the spleen. In one animal, a clear sequence of L. infantum ITS1 and a sequence of L. tropica hsp70 were obtained from the ear skin. Since hsp70 and ITS1 sequencing was not possible in three cats, the species of Leishmania infecting them was not determined. This is the first report of autochthonous infection with L. tropica in the Iberian Peninsula. Health care professionals, including physicians, dermatologists, and veterinarians, must be aware of this for a correct diagnosis, treatment, and management of possible co-infections.

Leishmaniasis is a chronic global arthropod‐borne zoonotic disease produced by several species of Leishmania with cutaneous, mucocutaneous, and visceral clinical manifestations. In Spain, only Leishmania infantum has been reported so far, although other species of Leishmania, such as L. tropica and L. major, are present in surrounding countries. The aim of this work is to analyze the occurrence of Leishmania spp. infection in European wildcats (Felis silvestris) as sentinels, including their genotypic characterization. Necropsies of 18 road‐killed wildcats were conducted. Samples of ear skin and spleen were taken for DNA isolation and PCR of the highly sensitive SSU-rDNA target. Subsequent PCR tests were performed using more specific targets for the determination of Leishmania species: hsp70 and ITS1. Positive samples were sequenced, and phylogenetic trees were constructed. Seven wildcats were found positive for Leishmania spp. Based on the hsp70 and ITS1 sequences, an animal was found to be infected only with L. tropica in ear skin samples, while two cats were found to be infected with L. infantum in both the ear skin and the spleen. In one animal, a clear sequence of L. infantum ITS1 and a sequence of L. tropica hsp70 were obtained from the ear skin. Since hsp70 and ITS1 sequencing was not possible in three cats, the species of Leishmania infecting them was not determined. This is the first report of autochthonous infection with L. tropica in the Iberian Peninsula. Health care professionals, including physicians, dermatologists, and veterinarians, must be aware of this for a correct diagnosis, treatment, and management of possible coinfections.

Leishmaniasis, a zoonotic parasitic disease transmitted by infected sandflies, impacts nearly 1 million people yearly and is endemic in many countries across Asia, Africa, the Americas, and the Mediterranean; despite this, it remains a neglected disease with limited effective treatments, particularly in impoverished communities with limited access to healthcare. This study aims to repurpose approved drugs for an affordable leishmaniasis treatment. After the screening of potential drug candidates by reviewing databases and utilizing molecular docking analysis, delamanid was chosen to be incorporated into solid lipid nanoparticles (SLNPs). Both in cellulo and in vivo tests confirmed the successful payload release within macrophages and through the epidermis following topical application on murine skin. The evaluation of macrophages infected with L. infantum amastigotes showed that the encapsulated delamanid exhibited greater leishmanicidal activity compared with the free drug. The process of encapsulating delamanid in SLNPs, as demonstrated in this study, places a strong emphasis on employing minimal technology, ensuring energy efficiency, cost-effectiveness, and reproducibility. It enables consistent, low-cost production of nanomedicines, even on a small scale, offering a promising step toward more accessible and effective leishmaniasis treatments.

Zoonotic leishmaniases are a worldwide public health problem for which the development of effective vaccines remains a challenge. A vaccine against leishmaniases must be safe and affordable and should induce cross-protection against the different disease-causing species. In this context, the DNA vaccine pHisAK70 has been demonstrated to induce, in a murine model, a resistant phenotype against L. major, L. infantum, and L. amazonensis. Moreover, a chimeric multiepitope peptide, HisDTC, has been obtained by in silico analysis from the histone proteins encoded in the DNA vaccine and has showed its ability to activate a potent CD4⁺ and CD8⁺ T-cell protective immune response in mice against L. infantum infection. In the present study, we evaluated the plasmid DNA vaccine pHisAK70 in comparison with the peptide HisDTC (with and without saponin) against L. major and L. infantum infection. Our preliminary results showed that both formulations were able to induce a potent cellular response leading to a decrease in parasite load against L. infantum. In addition, the DNA candidate was able to induce better lesion control in mice against L. major. These preliminary results indicate that both strategies are potentially effective candidates for leishmaniases control. Furthermore, it is important to carry out such comparative studies to elucidate which vaccine candidates are the most appropriate for further development.