Comparative Assessment of Induced Immune Responses Following Intramuscular Immunization with Fusion and Cocktail of LeIF, LACK and TSA Genes Against Cutaneous Leishmaniasis in BALB/c Mice

Leishmania vaccine development: A comprehensive review

Infectious diseases like leishmaniasis, malaria, HIV, tuberculosis, leprosy and filariasis are responsible for an immense burden on public health systems. Among these, leishmaniasis is under the category I diseases as it is selected by WHO (World Health Organization) on the ground of diversity and complexity. High cost, resistance and toxic effects of Leishmania traditional drugs entail identification and development of therapeutic alternative. Since the natural infection elicits robust immunity, consistence efforts are going on to develop a successful vaccine. Clinical trials have been conducted on vaccines like Leish-F1, F2, and F3 formulated using specific Leishmania antigen epitopes. Current strategies utilize individual or combined antigens from the parasite or its insect vector's salivary gland extract, with or without adjuvant formulation for enhanced efficacy. Promising animal data supports multiple vaccine candidates (Lmcen-/-, LmexCen-/-), with some already in or heading for clinical trials. The crucial challenge in Leishmania vaccine development is to translate the research knowledge into affordable and accessible control tools that refines the outcome for those who are susceptible to infection. This review focuses on recent findings in Leishmania vaccines and highlights difficulties facing vaccine development and implementation.

Anti-leishmanial therapy: Caught between drugs and immune targets

Leishmaniasis is an enigmatic disease that has very restricted options for chemotherapy and none for prophylaxis. As a result, deriving therapeutic principles for curing the disease has been a major objective in Leishmania research for a long time. Leishmania is a protozoan parasite that lives within macrophages by subverting or switching cell signaling to the pathways that ensure its intracellular survival. Therefore, three groups of molecules aimed at blocking or eliminating the parasite, at least, in principle, include blockers of macrophage receptor- Leishmania ligand interaction, macrophage-activating small molecules, peptides and cytokines, and signaling inhibitors or activators. Macrophages also act as an antigen-presenting cell, presenting antigen to the antigen-specific T cells to induce activation and differentiation of the effector T cell subsets that either execute or suppress anti-leishmanial functions. Three groups of therapeutic principles targeting this sphere of Leishmania-macrophage interaction include antibodies that block pro-leishmanial response of T cells, ligands that activate anti-leishmanial T cells and the antigens for therapeutic vaccines. Besides these, prophylactic vaccines have been in clinical trials but none has succeeded so far. Herein, we have attempted to encompass all these principles and compose a comprehensive review to analyze the feasibility and adoptability of different therapeutics for leishmaniasis.

Host–Pathogen Interaction in Leishmaniasis: Immune Response and Vaccination Strategies

Leishmaniasis is a zoonotic and vector-borne infectious disease that is caused by the genus Leishmania belonging to the trypanosomatid family. The protozoan parasite has a digenetic life cycle involving a mammalian host and an insect vector. Leishmaniasisis is a worldwide public health problem falling under the neglected tropical disease category, with over 90 endemic countries, and approximately 1 million new cases and 20,000 deaths annually. Leishmania infection can progress toward the development of species–specific pathologic disorders, ranging in severity from self-healing cutaneous lesions to disseminating muco-cutaneous and fatal visceral manifestations. The severity and the outcome of leishmaniasis is determined by the parasite’s antigenic epitope characteristics, the vector physiology, and most importantly, the immune response and immune status of the host. This review examines the nature of host–pathogen interaction in leishmaniasis, innate and adaptive immune responses, and various strategies that have been employed for vaccine development.

Evaluation of protection induced by in vitro maturated BMDCs presenting CD8+ T cell stimulating peptides after a heterologous vaccination regimen in BALB/c model against Leishmania major

Leishmaniasis is a complex vector-borne disease mediated by Leishmania parasite and a strong and long-lasting CD4⁺ Th1 and CD8⁺-T cell immunity is required to control the infection. Thus far multivalent subunit vaccines have met this requirement more promisingly. However several full protein sequences cannot be easily arranged in one construct. Instead, new emerging immune-informatics based epitope formulations surpass this restriction. Herein, we aimed to examine the protective potential of a dendritic cell based vaccine presenting epitopes to CD8⁺ and CD4⁺-T cells in combination with DNA vaccine encoding the same epitopes against murine cutaneous leishmaniasis. Immature DCs were loaded with epitopes (selected from parasite proteome) in vitro with or without CpG oligonucleotides and were used to immunize BALB/c mice. Peptide coding DNA was used to boost the system and immunological responses were evaluated after Leishmania (L.) major infectious challenge. The pre-challenge response to included epitopes was Th1 polarized which potentially lowered the infection at early time points post-challenge but not at later weeks. Collectively, DC prime-DNA boost was found to be a promising approach for Th1 polarization however the constituent epitopes undoubtedly make a significant contribution in the protection outcome of the vaccine.

Immunization against Leishmania major infection in BALB/c mice using a subunit-based DNA vaccine derived from TSA, LmSTI1, KMP11, and LACK predominant antigens

OBJECTIVES

To design a multivalent DNA vaccine encoding the most immunogenic regions of the Leishmania major antigens including TSA (Thiol-specific antioxidant protein), LmSTI1 (Leishmania major stress-inducible protein1), LACK (Leishmania homologue of receptors for activated C Kinase), and KMP11 (kinetoplastid membrane protein-11) on BALB/c mice.

MATERIALS AND METHODS

The chimeric construct was generated including the most immunogenic epitopes containing a combination of domains and oligopeptides of the aforementioned genes. The construct was cloned into pcDNA 3.1 plasmid and named "pleish-dom." Following intramuscular injection of mice, the capability of the vector pleish-dom alone and with pIL-12 (expressing murine IL-12) to raise protective cytokines and parasite burden was evaluated in the BALB/c mice as a susceptible animal model against L. major.

RESULTS

The immunized mice with pleish-dom/pIL-12 showed the highest and the lowest levels of interferon-gamma (IFN-γ) and interleukin-10 (IL-10), as well as the lowest leishmanin skin test (LST) reactions, were found through 8 weeks post-infection.

CONCLUSION

Although the obtained DNA vaccine from the immunogenic chimeric protein of L. major antigens was able to induce a high level of IFN-γ, it partially protected mice against L. major. However co-administration with pIL-12 led to shift immune response to Th1 phenotype, granuloma formation, and lowered parasite burden, and consequently distinct protection was found.

In-vitro and In-vivo Antileishmanial Activity of a Compound Derived of Platinum, Oxaliplatin, against Leishmania Major

This study aimed to evaluate the antileishmanial efficacy of oxaliplatin against Leishmania major (L. major) both in-vitro and in-vivo. The IC50, CC50, and SI of oxaliplatin against promastigotes, murine macrophages, Raw 264.7 cells, and intramacrophage amastigotes of L. major were investigated in-vitro. The effects of this drug on intracellular amastigotes were also assayed, and the percentage of infectivity and IIR were calculated. Flow cytometry was performed to assay apoptosis, using 50 and 100 µg/mL of oxaliplatin in the promastigotes and macrophages. In-vivo, the BALB/c mice were classified into three groups, receiving oxaliplatin, glucantime, and phosphate-buffered saline for one month, respectively. The lesion size, IFN-γ, and IL-4 levels, and parasite burden were also evaluated in the animals. After 72 h, the IC50 and CC50 of oxaliplatin against promastigotes and macrophages were respectively 0.5 and 66.78 µg/mL. The apoptosis of promastigotes and macrophages using 50 µg/mL of oxaliplatin was 7.25% and 2.14%, respectively, while apoptosis induced at 100 µg/mL was 15.48% and 2.80%, respectively. Similar to the glucantime group, the mice treated with oxaliplatin showed a lower parasite burden and smaller lesions, compared with the PBS group (p < 0.01). Furthermore, higher IFN-γ levels were reported in mice receiving oxaliplatin in comparison with those receiving PBS (p < 0.01). The current findings indicated the efficacy of oxaliplatin against promastigote and amastigote forms of Leishmania and L. major-induced leishmaniasis.