Nanometer-scale,
apolipoprotein-stabilized
phospholipid bilayer disk complexes (nanodisks [ND]) harboring the toxic and poorly soluble antileishmanial agent
amphotericin B (AMB) were examined for efficacy in treatment of Leishmania major-infected BALB/c mice (Mus musculus). L. major-infected mice were intraperitoneally (i.p.) treated with AMB-ND in 0-, 1-, and 5-mg/kg doses at 24 h, 48 h, and 4, 7, 14, and 21 days postinfection in two experiments. L. major-infected mice were i.p. treated with
phosphate-buffered saline, 5 mg/kg AMB-ND, or 5 mg/kg
lipid-associated
amphotericin B (
liposomal amphotericin B,
AmBisome) at 24 h, 48 h, and 10, 20, 30, and 40 days postinfection in one experiment. Parasite numbers, footpad lesion size progression, and development of
cytokine responses were assayed at days 7, 15, 30, 50, 140, and 250 or at days 14, 30, 50, 95, and 140 postinfection. Mice administered AMB-ND in 1- or 5-mg/kg doses were significantly protected from L. major, displaying decreases in lesion size and parasite burden, particularly at the 5-mg/kg dosage level. In contrast to the i.p. treated
AmBisome group, BALB/c mice treated with i.p. AMB-ND completely cleared an L. major
infection by 140 to 250 days postinfection, with no lesions remaining and no parasites isolated from infected animals. Restimulated mixed lymphocyte culture
cytokine responses (
interleukin-4 [IL-4],
IL-12, IL-10, NO, and
gamma interferon) were unchanged by AMB-ND administration compared to controls. The marked clearance of Leishmania parasites from a susceptible strain of mice without an appreciable change in the
cytokine response suggests that AMB-ND represent a potentially useful formulation for treatment of intrahistiocytic organisms.