KNOCKDOWN OF HOST ANTIOXIDANT DEFENSE GENES ENHANCES THE EFFECT OF GLUCANTIME ON INTRACELLULAR Leishmania braziliensis IN HUMAN MACROPHAGES [PublishAheadOfPrint]

Leishmaniasis is a neglected tropical disease affecting millions of people worldwide and represents a major public health problem. Information on protein expression patterns and functional roles within the context of Leishmania-infected human monocyte-derived macrophages (MDMs) under drug treatment conditions are essential to understand the role of these cells in leishmaniasis treatment. We analyzed functional changes in expression of human MDM genes and proteins during in vitro infection by Leishmania braziliensis and treatment with Glucantime (Sb^V) using quantitative polymerase chain reaction (qPCR) arrays, western blotting, confocal microscopy and short-interfering RNA (siRNA) human gene-inhibition assays. Comparison of the results from gene transcription and protein expression analyses revealed that GSTP1, GCLM, GSR, GSS, TXN, and ABCB5 were strongly upregulated at both mRNA and protein levels in human MDMs infected and treated compared to the control group. Subcellular localization studies showed a primarily phagolysosomal location for the ABCB5 transporter, indicating that this protein may be involved in the transport of Sb^V. By inducing a decrease in L. braziliensis intracellular survival in THP-1 macrophages, siRNA silencing of GSTP1, GSS and ABCB5 resulted in an increased leishmanicidal effect of Sb^V exposure in vitro. Our results suggest that human MDMs infected with L. braziliensis and treated with Sb^V express increased levels of genes participating in antioxidant defense, whereas our functional analyses provide evidence for the involvement of human MDMs in drug detoxification. Therefore, we conclude that proteins GSS, GSTP1 and ABCB5 represent potential targets for enhancing the leishmanicidal activity of Glucantime.

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