Mannose-capped lipoarabinomannan (ManLAM) is an immunomodulatory epitope of Mycobacterium tuberculosis (Mtb). An aptamer (ZXL1) that specifically binds to ManLAM from the virulent Mtb H37Rv strain was previously generated and it was found that ZXL1 functions as an antagonist, inhibiting the ManLAM-induced immunosuppression of DCs. In the present study, it was found that ZXL1 inhibits Mtb entry into murine macrophages and that ZXL1 enhances IL-1β and IL-12 mRNA expression and cytokine production in ManLAM-treated macrophages but decreases IL-10 production. Inducible nitric oxide synthase expression in macrophages was upregulated in the presence of ZXL1 after stimulation with ManLAM. ZXL1 was also found to inhibit expression of lipid-sensing nuclear receptor peroxisome proliferator-activated receptor γ (PPAR-γ). These results suggest that ZXL1 promotes anti-tuberculosis activity through downregulation of PPAR-γ expression, which may contribute to M1 macrophage polarization and Mtb killing by macrophages.
Keywords: aptamer; inducible nitric oxide synthase; mannose-capped lipoarabinomannan.
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