Restoration of IFNγR Subunit Assembly, IFNγ Signaling and Parasite Clearance in Leishmania donovani Infected Macrophages: Role of Membrane Cholesterol

• DOI: 10.1371/journal.ppat.1002229
• Publication Date: 2011-09-09T04:37:29Z
• Authors: Subha Sen; Koushik Roy; Sandip Mukherjee; Rupkatha Mukhopad...; Syamal Roy
• Keywords: Lipophosphoglycan; Lipid raft; Phagolysosome

Despite the presence of significant levels systemic Interferon gamma (IFNγ), host protective cytokine, Kala-azar patients display high parasite load with downregulated IFNγ signaling in Leishmania donovani (LD) infected macrophages (LD-MØs); cause such aberrant phenomenon is unknown. Here we reveal for first time mechanistic basis impaired parasitized murine macrophages. Our study clearly shows that LD-MØs receptor (IFNγR) expression and their ligand-affinity remained unaltered. The intracellular parasites did not pose any generalized defect as IL-10 mediated signal transducer activator transcription 3 (STAT3) phosphorylation unaltered respect to normal. Previously, showed are more fluid than normal MØs due quenching membrane cholesterol. decreased rigidity was derived lipophosphoglycan (LPG) because purified LPG failed alter fluidity MØs. IFNγR subunit 1 (IFNγR1) 2 (IFNγR2) colocalize raft upon stimulation MØs, but this absent LD-MØs. Oddly enough, association IFNγR1 IFNγR2 could be restored liposomal delivery cholesterol evident from fluorescence resonance energy transfer (FRET) experiment co-immunoprecipitation studies. Furthermore, treatment together allowed reassociation assembly (phospho-JAK1, JAK2 STAT1) LD-MØs, appropriate signaling, subsequent killing. This effect specific analogue 4-cholestene-3-one restore response. binding motifs [(L/V)-X1–5-Y-X1–5-(R/K)] transmembrane domain also noted. interaction peptides representing motif studied cholesterol-liposome analogue-liposome difference two orders magnitude respective affinity (KD: 4.27×10−9 M versus 2.69×10−7 M). These observations reinforce importance regulation function proteins. demonstrates during its life-cycle LD perturbs ligand driven by MØ