Exosomes isolated from M.tb infected cells modulate macrophage response to IFN-gamma

we studied the role of exosomes isolated from M.tb infected macrophages in modulating the macrophage response to IFN-γ. Nimblegen microarray gene expression studies were used to compare the suppression of IFN-γ inducible genes by exosomes relative to the virulent strain of M.tuberculosis. Overall our study suggest that exosomes, as carriers of M.tb pathogen associated molecular patterns (PAMPs), may provide a mechanistic link by which M.tb may exert its suppression of host immune response beyond the infected cell, and implies a physiological role for exosomes in immune surveillance of TB. Macrophages were treated with exosomes, infected with M.tb H37Rv or left untreated for 18 hours followed by +/- IFN-γ for an additional 18 hours. Cells were harvested and RNA was isolated and converted to double stranded cDNA and subsequently labeled and hybridized onto Mus musculus 4×72 Nimblegen microarray using Nimblegen Hybridization system 4 according to manufacturer’s instructions (Roche)