Leishmania donovani Isolates with Antimony-Resistant but Not -Sensitive Phenotype Inhibit Sodium Antimony Gluconate-Induced Dendritic Cell Activation

PLoS Pathogens

Alpana Singh¹  Vinod Yadav¹  Pradip Sen¹  Eshu Singhal¹  Syamal Roy²  Arun Kumar Haldar²  Rajatava Basu²  Suniti Bhaumik²  Kamlesh Kumar Bisht³ 

[1] Division of Cell Biology and Immunology, Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India;Division of Infectious Diseases and Immunology, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, India;Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India

关键词: Transcription factors;    Parasitic diseases;    Promastigotes;    DNA-binding proteins;    Amastigotes;    Electrophoretic mobility shift assay;    Antimony;    Kala-azar;   

DOI  :  10.1371/journal.ppat.1000907

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The inability of sodium antimony gluconate (SAG)-unresponsive kala-azar patients to clear Leishmania donovani (LD) infection despite SAG therapy is partly due to an ill-defined immune-dysfunction. Since dendritic cells (DCs) typically initiate anti-leishmanial immunity, a role for DCs in aberrant LD clearance was investigated. Accordingly, regulation of SAG-induced activation of murine DCs following infection with LD isolates exhibiting two distinct phenotypes such as antimony-resistant (SbRLD) and antimony-sensitive (SbSLD) was compared in vitro. Unlike SbSLD, infection of DCs with SbRLD induced more IL-10 production and inhibited SAG-induced secretion of proinflammatory cytokines, up-regulation of co-stimulatory molecules and leishmanicidal effects. SbRLD inhibited these effects of SAG by blocking activation of PI3K/AKT and NF-κB pathways. In contrast, SbSLD failed to block activation of SAG (20 µg/ml)-induced PI3K/AKT pathway; which continued to stimulate NF-κB signaling, induce leishmanicidal effects and promote DC activation. Notably, prolonged incubation of DCs with SbSLD also inhibited SAG (20 µg/ml)-induced activation of PI3K/AKT and NF-κB pathways and leishmanicidal effects, which was restored by increasing the dose of SAG to 40 µg/ml. In contrast, SbRLD inhibited these SAG-induced events regardless of duration of DC exposure to SbRLD or dose of SAG. Interestingly, the inhibitory effects of isogenic SbSLD expressing ATP-binding cassette (ABC) transporter MRPA on SAG-induced leishmanicidal effects mimicked that of SbRLD to some extent, although antimony resistance in clinical LD isolates is known to be multifactorial. Furthermore, NF-κB was found to transcriptionally regulate expression of murine γglutamylcysteine synthetase heavy-chain (mγGCShc) gene, presumably an important regulator of antimony resistance. Importantly, SbRLD but not SbSLD blocked SAG-induced mγGCS expression in DCs by preventing NF-κB binding to the mγGCShc promoter. Our findings demonstrate that SbRLD but not SbSLD prevents SAG-induced DC activation by suppressing a PI3K-dependent NF-κB pathway and provide the evidence for differential host-pathogen interaction mediated by SbRLD and SbSLD.

【 授权许可】

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