Role of SLAM on macrophages functions against Mycobacterium tuberculosis

ANGELA MARIA BARBERO; GUADALUPE INÉS ALVAREZ; RODRIGO EMANUEL HERNÁNDEZ DEL PINO; VICTORIO GABRIEL PALACIO; GARCÍA VERÓNICA; PASQUINELI, V

Congreso; IV Congress of LASID (LASID2015); 2015

Tuberculosis affects onethirdof world?s population and millions of new cases are reportedannually. Mycobacterium tuberculosis (Mtb) has the ability to survive within host´s macrophageswhich is key to its persistence and pathogenesis. Signaling lymphocyteactivationmolecule(SLAM), expressed in hematopoietic cells, is a selfligandand a costimulatory molecule thatenhance Th1 response against Mtb. SLAM can also act as a bacterial sensor regulating Gramnegativebacteria removal from macrophages. Here, we explored SLAM role on macrophagesfunctions against Mtb.Methods. THP1cells differentiated with PMA were stimulated with sonicatedMtb.Humanmonocytederivedmacrophages were obtain from healthy donors. SLAM expression wasdetermined by flow cytometry (FC) and bacterial uptake by using rhodaminestainedMtb. 6carboxy2\',7\'dichlorodihydrofluoresceindiacetate was used to measure reactive oxygen species(ROS) by FC in macrophages stimulated with Mtb plus agonistic antiSLAM. SLAM/CD107b (a lateendosome marker) coexpressionwas evaluated by fluorescence microscopy.Results. Our findings show that Mtb induces SLAM expression in differentiated THP1cells unliketo macrophages which have strong constitutive levels. Interestingly, the great majority ofphagocytic macrophages (84.82%) were SLAM+ as seen by rhodamineMtbuptake.The percentages of ROS+ cells were similar between macrophages stimulated with Mtb and thoseadditionally costimulated through SLAM. However, SLAM costimulation enhanced the mediumintensity fluorescence suggesting that SLAM induces ROS production. Moreover, preliminaryresults indicate that CD107b is coexpressedwith SLAM in THP1cells.Conclusions. Our results show that macrophages´s SLAM expression enhance the microbicidalresponse against Mtb. Further studies are needed to show SLAM role as a mycobacterial sensor.