The effect of treatment with a non-ionic surfactant vesicular formulation of sodium stiogluconate on host immune responses and serum metabolites in a murine model of Leishmania donovani

Raphael Taiwo Aruleba¹Bernard Osero²Du Toit Loots³Laneke Luies³Zama Cele¹Priscilla Abena Ankamaa Opare¹Mari van Reenen³Frank Brombacher²Katharine Carter⁴Ramona Hurdayal^1*

• ¹Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa
• ²Division of Immunology, Department of Pathology, Faculty of Health Sciences, Institute of Infectious Diseases and Molecular Medicine (IDM), South African Medical Research Council (SAMRC) on Immunology of Infectious Diseases, University of Cape Town, Cape Town, South Africa
• ³Focus Area Human Metabolomics, North-West University, Potchefstroom, South Africa
• ⁴Strathclyde Institute of Pharmacy and Biomedical Sciences, Faculty of Science, University of Strathclyde, Glasgow, Scotland, United Kingdom

Visceral leishmaniasis (VL), caused by Leishmania donovani, is associated with parasite-induced immunological and physiological changes that ensure the survival of amastigotes within the host. Both the parasite and the host have nutritional requirements, and for auxotrophic Leishmania, dependence on the host to supply specific growth requirements is essential. This highlights an intricate link between host immunity and metabolism during VL. This study explores the interplay between the host metabolome and immune responses pre-and post-infection and treatment, aiming to identify early metabolite markers of therapeutic success against Leishmania. BALB/c mice infected with L. donovani were divided into cured and non-cured groups based on treatment with a non-ionic surfactant vesicle formulation of sodium stibogluconate (300 mg Sb v /kg, SSG-NIV) or PBS. Specific immune responses and serum metabolite levels were then determined up to day 60 PI using untargeted GC×GC-TOFMS metabolomics. Treatment effectively reduced parasite loads, triggering heightened CD4+ and CD8+ T-cell responses at day 21, with increased IFN-γ, IL-12, and IL-4, and decreased IL-10 and TGF-β. Metabolomics analysis identified changes in glycolysis, fatty acid and amino acid metabolism 1-week PI, suggesting an increased Warburg effect to supplement parasite survival and initiation of immune responses. Valine, lactic acid, and glycerol-1-oleate were identified as markers of early infection. Treatment with SSG-NIV altered metabolism of major macromolecules and the TCA cycle between cured and non-cured groups. Additionally, glycine, galactose, xylose, and ribitol show promise as immune correlates for antiparasitic therapies. These findings highlight the diagnostic and prognostic potential of serum-derived metabolites in monitoring host immune responses to VL and treatment.