Real-Time Reverse Transcription-PCR Quantification of Cytokine mRNA Expression in Golden Syrian Hamster Infected with Leishmania infantum and Treated with a New Amphotericin B Formulation

Abstract

ABSTRACT A real-time quantitative reverse transcription-PCR assay was developed for the quantification of cytokine mRNA expression in the golden Syrian hamster Mesocricetus auratus infected with Leishmania infantum and treated with amphotericin B (AMB) formulated in microspheres made of human serum albumin (HSA). Treatment was administered intravenously on days 69, 71, and 73 postinfection (p.i.) with 10 7 metacyclic promastigotes, at doses of 2 and 40 mg/kg of AMB. High infection levels were recorded for untreated animals by day 76 p.i., with parasite loads always about 2 log 10 per gram higher in the liver than in the spleen. Treatment was highly effective with both doses, but at 40 mg/kg, almost complete parasite elimination was achieved. mRNA expression of gamma interferon (IFN-γ) and, to a lesser extent, tumor necrosis factor alpha (TNF-α) and transforming growth factor beta (TGF-β) in spleen cells was up-regulated in most animals of the untreated group. The mRNA expression of interleukin-4 was strongly down-regulated in untreated as well as treated infected animals. Treatment with the lower dose of AMB-HSA down-regulated the mRNA expression of IFN-γ and TNF-α, with no effect on the deactivating cytokine TGF-β. In contrast, treatment with the higher dose (40 mg/kg) of the formulation caused moderate up-regulation of IFN-γ and TNF-α and strong suppression of TGF-β. Treatment of noninfected animals did not alter the cytokine expression pattern with regard to untreated controls. Our results suggest that treatment of L. infantum -infected Syrian hamsters with highly effective nontoxic doses of AMB-HSA causes deactivation of the anti-inflammatory cytokine TGF-β, which in turn results in up-regulation of the Th1 cytokines IFN-γ and TNF-α.