Therapy with sodium stibogluconate in stearylamine-bearing liposomes confers cure against SSG-resistant Leishmania donovani in BALB/c mice

PLoS One. 2011 Mar 10;6(3):e17376. doi: 10.1371/journal.pone.0017376.

Abstract

Background: Resistance of Leishmania donovani to pentavalent antimonials, the first-line treatment of visceral leishmaniasis (VL), has become a critical issue worldwide. Second-line and new drugs are also not devoid of limitations. Suitable drug-delivery systems can improve the mode of administration and action of the existing antimonials, thus increasing their clinical life.

Methodology/principal findings: We investigated the efficacy of sodium stibogluconate (SSG) in phosphatidylcholine (PC)-stearylamine-bearing liposomes (PC-SA-SSG), PC-cholesterol liposomes (PC-Chol-SSG) and free amphotericin B (AmB) against SSG-resistant L. donovani strains in 8-wk infected BALB/c mice. Animals were sacrificed and parasites in liver, spleen and bone marrow were estimated 4-wk post-treatment by microscopic examination of stamp smears and limiting dilution assay. A set of PC-SA-SSG and AmB treated mice were further studied for protection against reinfection. Serum antibodies and cytokine profiles of ex-vivo cultured splenocytes were determined by ELISA. Uptake of free and liposomal SSG in intracellular amastigotes was determined by atomic absorption spectroscopy. Rhodamine 123 and 5-carboxyfluorescein, known substrates of Pgp and MRP transporter proteins, respectively, were used in free and liposomal forms for efflux studies to estimate intracellular drug retention. Unlike free and PC-Chol-SSG, PC-SA-SSG was effective in curing mice infected with two differentially originated SSG-unresponsive parasite strains at significantly higher levels than AmB. Successful therapy correlated with complete suppression of disease-promoting IL-10 and TGF-β, upregulation of Th1 cytokines and expression of macrophage microbicidal NO. Cure due to elevated accumulation of SSG in intracellular parasites, irrespective of SSG-resistance, occurs as a result of increased drug retention and improved therapy when administered as PC-SA-SSG versus free SSG.

Conclusions/significance: The design of this single-dose combination therapy with PC-SA-SSG for VL, having reduced toxicity and long-term efficacy, irrespective of SSG-sensitivity may prove promising, not only to overcome SSG-resistance in Leishmania, but also for drugs with similar resistance-related problems in other diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amines / chemistry*
  • Animals
  • Antigens, Protozoan / immunology
  • Antimony Sodium Gluconate / pharmacology*
  • Antimony Sodium Gluconate / therapeutic use*
  • Antiprotozoal Agents / pharmacology
  • Antiprotozoal Agents / therapeutic use
  • Cell Proliferation / drug effects
  • Cytokines / biosynthesis
  • Drug Resistance / drug effects*
  • Fluoresceins / metabolism
  • Immunity, Humoral / drug effects
  • Immunomodulation / drug effects
  • Leishmania donovani / drug effects*
  • Leishmania donovani / immunology
  • Leishmaniasis, Visceral / drug therapy
  • Leishmaniasis, Visceral / immunology
  • Leishmaniasis, Visceral / parasitology
  • Liposomes / chemistry*
  • Mice
  • Mice, Inbred BALB C
  • Nitric Oxide / biosynthesis
  • Phosphatidylcholines / chemistry
  • Rhodamine 123 / metabolism
  • Spleen / drug effects
  • Spleen / immunology

Substances

  • Amines
  • Antigens, Protozoan
  • Antiprotozoal Agents
  • Cytokines
  • Fluoresceins
  • Liposomes
  • Phosphatidylcholines
  • Rhodamine 123
  • Nitric Oxide
  • 4-carboxyfluorescein
  • stearylamine
  • Antimony Sodium Gluconate