Recent scientific evidence indicates that distinct patterns of susceptibility in BALB/c mice to Leishmania major infection are attributable to the differential expansion of distinct CD4+ T-cell subsets and their cytokines production. Production of the Th1 cytokine IFN-g is associated with resistance, whereas production of the Th2 cytokines IL-4 and IL-10 are associated with extreme susceptibility. The major host immune defense mechanism against Leishmania is activation of macrophages by INF-? derived from T cells. The inability of susceptible hosts to mount the immune response necessary to activate macrophage and destroy the parasites may be due to the parasite-specific proteins that are able to suppress the immune system. In the present study, we have semi-purified the excreted antigens of Leishmania major promastigote and amastigote by column chromatography. The isolated fraction showed a potent immunosuppressive activity on normal BALB/c mice lymphocytes stimulated with mitogens. Fifteen microgram of the isolated fraction caused 81% suppression of lymphocyte proliferation. These data may suggest that the parasite by secreting immunosuppressive factor down regulate the immune system and as a result survive in the body.

Background: A lizard Leishmania has been isolated from a lizard (Agama agilis) in Iran. Its genome sequence has not been determined, so far. Methods: The study was done at Shahid Beheshti University of Medical Sciences, Tehran, Iran in 2017-2023. Leishmania promastigotes were cultured in RPMI1640 culture medium and collected at logarithmic phase by centrigugation. Parasite RNA was extracted by the Qiagene standard kit and its quantity and quality was determined and sequenced by NGS method with Illumina PE machine at BGI Company (China). Results: The number of 8316 mRNA, 83 tRNA, 63 rRNA, 83 ncRNA, 5 snRNA, 1039 snoRNA, 36 region, and 3 repeat regions, 8343 CDS, 9597 Exon and 9292 Genes were identified in promastigote of Iranian lizard Leishmania. Conclusion: Genomic elements of Iranian lizards Leishmania (with unique characteristics) were determined and identified by NGS system.

Background: Today, most patients with cutaneous leishmaniasis are treated with drugs such as glucantime; however, severe drug resistance to these drugs is found, in addition to recurrence, extensive drug complications, and secondary infections in many patients. Objectives: Therefore, due to the lack of sufficient information on this subject, this study was undertaken for the first time to investigate the antimicrobial activity of multifunctional lactoferrin as one of the most important bioactive compounds on amastigotes and promastigotes forms of Leishmania major in vitro. Methods: In this study, six concentrations of lactoferrin (2. 5, 5, 10, 20, 40, and 80  g/mL) were added to parasite cultures at specified times. The MTT was done. Leishmania major promastigotes were incorporated to J774 cells and then incubated for 72 hours. The results were compared with the results of glucantime, as a standard. In the end, flow cytometry was performed to investigate apoptosis. Results: After 24, 48, and 72 hours of incubation in the presence of various concentrations of lactoferrin, the number of amastigotes and promastigote parasites increased over time without any significant difference compared to the control group (P > 0. 05), but it was significant compared to glucantime at the 80  g/mL concentration (P < 0. 05). Besides, lactoferrin showed very low toxicity effects on macrophages and stimulated the growth of both forms of L. major parasite. Conclusions: Our findings indicated that lactoferrin could not induce early and late apoptosis in both forms of L. major.

Purpose: Here, we aim to evaluate the antileishmanial activity of compounds with a benzoxazinoid (BX) skeleton, previously synthesized by our group, against Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum promastigotes. Methods: Anti-promastigote activity, as well as cytotoxicity, were determined using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assays. The selectivity index (SI) for each compound was calculated using a ratio of the cytotoxicity of compounds and the geometric mean (GM) of antileishmanial concentrations to each species tested. The comparisons between groups were carried out using a t test or analysis of variance (one-way ANOVA). A P value of less than 0. 05 was considered significant. Results: All the compounds tested were active, with IC50 falling between 92 ± 6. 19 μ g/mL and 238± 6. 57 μ g/mL for L. braziliensis, and 89 ± 6. 43 μ g/mL and 188 ± 3. 58 μ g/mL against L. infantum. Bex2, Bex3, Pyr1, Pyr2, and Pyr4 were compounds that showed activity similar to the drug Glucantime® , exhibited low cytotoxicity against splenic hamster cells (CC50 raging between >400 and 105. 7± 2. 26 μ g/mL) and had favorable selectivity indices (SI 1. 12 to 3. 96). Conclusion: The analogs in question are promising prototypes for the pharmaceutical development of novel, safer and more effective leishmanicidal agents.