The Effect of Curcumin on the Expression of INFγ, TNF-α, and iNOS Genes in PBMCs Infected with Leishmania major [MRHO/IR/75/ER].

BACKGROUND: Leishmaniasis, caused by the Leishmania parasite, is one of the most important tropical neglected diseases. The urgent search for effective, inexpensive, and preferably herbal anti-leishmanial agents, is needed. OBJECTIVE: Curcumin is a natural polyphenolic compound derived from turmeric that is well known for its antioxidant, anti-inflammatory, anti-tumor, and anti-cancer activity. METHODS: The present work evaluates the anti-leishmanial [Leishmania major] activity of curcumin. The infected PBMCs were treated with curcumin. The ROS level at 6, 12, 24 h and gene expression levels at 24, 48, and 72 h of PBMCs after treatment with curcumin were determined. RESULTS: Based on the results, the curcumin concentrations of 268 µM [24 h] and 181.2 µM [72 h] were defined as IC50 against L. major promastigotes. Treatment of L. major infected-peripheral blood mononuclear cells [PBMCs] with IC50 concentrations of curcumin, depending on exposure time, significantly induced the reactive oxygen species [ROS] generation and increased the expression levels of interferongamma [IFN-γ], tumor necrosis factor-alpha [TNF-α], and nitric oxide synthase [iNOS] genes. CONCLUSION: These findings suggest the potential of curcumin against Leishmaniasis.

Arginase/nitric oxide modifications using live non-pathogenic Leishmania tarentolae as an effective delivery system inside the mammalian macrophages.

Recombinant live delivery system based on chemokine IFN-γ-inducible protein-10 kDa (CXCL 10 or IP-10), as a suitable immunotherapy tool, have been used for the treatment of Leishmania infections. This chemokine can defeat Leishmania spp. infection via producing nitric oxide (NO) for parasite killing. This study was performed to investigate the effects of IP-10 on the infected human macrophages by L. tarentolae expressing IP-10. We also quantified the arginase activity and NO production in the co-cultured human macrophages with L. tarentolae expressing IP-10 as compared with wild L. tarentolae. The results elucidate that in the infected cells with L. tarentolae expression of IP-10 the arginase activity decreased, and inversely, NO production intensely increased. Altogether, L. tarentolae expressing IP-10 shows a favorable therapeutic tool to improve the treatment of Leishmania infection. This work suggests that L. tarentolae expressing IP-10 cause specific effects on the metabolic pathways of the macrophage host, which might enable the host cells in killing of parasites and decreasing the survival of them against Leishmania infection.

Construction of a Novel DNA Vaccine Candidate encoding LmSTI1-PpSP42 Fusion Protein from Leishmania major and Phlebotomus papatasi against Cutaneous Leishmaniasis.

Background: Cutaneous leishmaniasis (CL) is a serious public health problem in many tropical countries. The infection is caused by a protozoan parasite of Leishmania genus transmitted by Phlebotominae sandflies. In the present study, we constructed a eukaryotic expression vector to produce a fusion protein containing LmSTI1 from Leishmania major (L. major) and PpSP42 from Phlebotomus papatasi (Ph. papatasi). In future studies we will test this construct as a DNA vaccine against zoonotic CL. Methods: The nucleotide sequences encoding the LmSTI1 protein and a fragment encoding 79% of PpSP42 were amplified using L. major and Ph. papatasi genomic DNA, respectively. The amplicons were cloned into the pcDNA3.1(+) eukaryotic expression vector. The recombinant plasmid pcDNA-LmSTI1Pp42 was propagated in Escherichia coli (E. coli) and used to transfect HEK-293T cells. The expressed fusion protein was analyzed by Western blotting using anti-LmSTI1 mouse serum. Results: Sequences encoding LmSTI1 and partial PpSP42 were cloned into pcDNA3.1(+). Production of the recombinant LmSTI1Pp42 fusion protein was confirmed by Western blotting. Conclusion: An LmSTI1Pp42 fusion protein was expressed HEK-293T cells. This construct may be an effective DNA vaccine against CL.