biostudies-literatureKeyhani AVice Chancellor for Research and Technology, Kerman University of Medical Sciences360https://www.ebi.ac.uk/biostudies/studies/S-EPMC12379411biostudies-literatureUnknown18(1)Macrophages are essential immune cells during Leishmania infection, as their polarization toward M1/M2 phenotypes determines disease outcome. This study aimed to investigate the modulatory effects of leptin, alone and in combination with glucantime, on macrophage polarization in Leishmania tropica infection. Human THP-1-derived macrophages infected with L. tropica were treated with leptin (5 or 10 ng/ml), glucantime (100 or 200 μg/ml), or their combinations. The cytotoxic effects, parasite survival, reactive oxygen species (ROS), nitric oxide (NO) generation, and expression of M1/M2 acrophage-related parameters were evaluated using standard methods. Both leptin doses significantly increased the expression of M1-associated markers (CD86, iNOS, SOCS3, miR-155) and pro-inflammatory cytokines (TNF-α, IL-12, IFN-γ) while decreasing M2-associated markers (CD206, ARG1, SOCS1, miR-146a) and anti-inflammatory cytokines (IL-4, IL-10, TGF-β). The leptin-glucantime combinations showed synergistic effects, shifting macrophage polarization toward the M1 phenotype more than either treatment alone. In particular, the combination of 10 ng/ml leptin with 100 μg/ml glucantime completely eliminated intracellular amastigotes and showed a superior selectivity index (17.66) compared to mono-treatment (leptin: 7.88; glucantime: 6.87). The findings indicate that leptin enhances the efficacy of glucantime against L. tropica by promoting M1 macrophage polarization. This presents a potential therapeutic approach that may lower conventional drug doses and associated toxicity while preserving or even improving treatment outcomes.Parasites & vectorsLeptin enhances the efficacy of glucantime to modulate macrophage polarization toward the M1 phenotype in Leishmania tropica-infected macrophages.PMC12379411401000284Keyhani AJafarzadeh ASharifi ISalarkia EfalseLeptin enhances the efficacy of glucantime to modulate macrophage polarization toward the M1 phenotype in Leishmania tropica-infected macrophages.Macrophages are essential immune cells during Leishmania infection, as their polarization toward M1/M2 phenotypes determines disease outcome. This study aimed to investigate the modulatory effects of leptin, alone and in combination with glucantime, on macrophage polarization in Leishmania tropica infection. Human THP-1-derived macrophages infected with L. tropica were treated with leptin (5 or 10 ng/ml), glucantime (100 or 200 μg/ml), or their combinations. The cytotoxic effects, parasite survival, reactive oxygen species (ROS), nitric oxide (NO) generation, and expression of M1/M2 acrophage-related parameters were evaluated using standard methods. Both leptin doses significantly increased the expression of M1-associated markers (CD86, iNOS, SOCS3, miR-155) and pro-inflammatory cytokines (TNF-α, IL-12, IFN-γ) while decreasing M2-associated markers (CD206, ARG1, SOCS1, miR-146a) and anti-inflammatory cytokines (IL-4, IL-10, TGF-β). The leptin-glucantime combinations showed synergistic effects, shifting macrophage polarization toward the M1 phenotype more than either treatment alone. In particular, the combination of 10 ng/ml leptin with 100 μg/ml glucantime completely eliminated intracellular amastigotes and showed a superior selectivity index (17.66) compared to mono-treatment (leptin: 7.88; glucantime: 6.87). The findings indicate that leptin enhances the efficacy of glucantime against L. tropica by promoting M1 macrophage polarization. This presents a potential therapeutic approach that may lower conventional drug doses and associated toxicity while preserving or even improving treatment outcomes.2025-01-01T00:00:00Z2025 Aug2026-05-09T17:58:30.066Z2026-04-08T01:08:19.057ZS-EPMC123794114085534010.1186/s13071-025-07004-6