IMMUNE RESPONSES INDUCED UPON INFECTION OF HUMAN MONOCYTES FROM TUBERCULOSIS PATIENTS WITH LIVE Mycobacterium tuberculosis STRAINS

TATEOSIAN, NANCY; PELLEGRINI, J; AMIANO, N; HERNANDEZ DEL PINO, R; CASCO; PALMERO, D; GUTIERRES, M; GARCIA, V

Congreso; 1 Meeting LASID FAIC SAI; 2015

Background: A deeper comprehension of Mycobacterium tuberculosis(Mtb) pathogenesis is essential for setting new preventive strategies. Mycobacterium RD1-locus encodes a specialized secretion system and virulence effector proteins that contributes to mycobacterial regulation of host immune responses. Autophagy was shown to display a critical role during human immune response against Mtb. Actually; autophagy induction promotes maturation of Mtb-containing phagosomes, suppressing mycobacterial survival. Here we investigated the modulation of the autophagy process and the production of cytokines in monocytes infected with a RD1 deleted-Mtb-strain(MtbdeltaRD1), or MtbH37Rv pathogenic strain.Methods:Peripheral blood mononuclear cells(PBMCs) from healthy donors(HD) and tuberculosis patients(TB) were either infected with MtbH37Rv or MtbdeltaRD1, or stimulated with sonicatedMtb(Mtb-Ag), ±bafilomycinA1(BafA1). After 24h, we determined the autophagy levels(LC3-II) by Western Blot and Immunofluorescence microscopy. IFN-gamma and TNF-alpha levels were analyzed byELISA.Results:In contrast to MtbH37Rv, a strain known to interfere with the phagosome maturation pathway, after infection with MtbdeltaRD1, monocytes displayed high levels of LC3-IIB/puncta. Thus, MtbdeltaRD1strain was able to induce a functional autophagic process, as evidenced by a significant increased of LC3-IIBpuncta/cell in the presence of BafA1. Furthermore, we observed the same effect after stimulating PBMCs withMtb-Ag. Besides, increased levels of TNF-alpha were secreted by cells stimulated with Mtb-Ag or infected withMtbdeltaRD1-strain. Finally, HD produced significantly higher IFN-gamma levels than TB in response to MtbdeltaRD1 or Mtb-Ag. However, MtbdeltaRD1 infection induced marked lower IFN-gamma production by PBMCs from TB and HD as compared toMtb-Ag-stimulated PBMCs. Conclusions:In contrast to MtbH37Rv, MtbdeltaRD1 strain induces the autophagic flux in human monocytes, positively modulating IFN-gamma and TNF-alpha production.