ROLE OF IROS IN APOPTOSIS INDUCED BY DIFFERENT MTB STRAINS IN ARGENTINA

ROMERO, MARÍA; ; BALBOA, LUCIANA; ; LÓPEZ, BEATRIZ; ; BARRERA, LUCÍA; ; SASIAIN, MARÍA;; ALEMÁN, MERCEDES

Congreso; Primer Congreso Franco-Argentino de Inmunología; 2010

One-third of the world’s population is infected with Mycobacterium tuberculosis (Mtb). Prevalent Mtb lineages in Argentina are European-Latin American-Mediterranean (LAM) and Haarlem (H), sensible (s) as well as multi-resistance to drugs (r) strains (M and 410). Polymorphonuclear neutrophils (PMN) play a crucial role in immune response against Mtb being the first cells to arrive at sites of infection where once activated limit infection through their antimicrobial functions. We have previously evaluated the immune response generated by clinical isolates compared with the widely described H37Rv strain and we found that LAMs induced higher PMN activation and apoptosis compared with Hs, 410 and specially M strain. Objective: To evaluate weather differences in apoptosis depends on ROS production generated by Mtb strains, and to describe the mechanisms involved. Methods: 3 x 106/ml human peripheral PMN were cultured 18 h with or without Mtb strains and thereafter apoptosis (AV binding) (2:1 ratio) were measured using FACScan. Alternatively, Mtb induced apoptosis was evaluated after addition of H2O2 or NADPH oxidase inhibitor (DPI). ROS production (123DHR oxidation) were determined by 1 h culture (1:50 ratio PMN: strain). Optional LPS were used as priming agent 1 h before culture. Results: LAMs induced a higher ROS production compared to H strains (p<0.05) that was enhanced by LPS priming (p<0.05) while it did not improve other strains response. Apoptosis induced by all strains was prevented by DPI (p<0.002) and was restored in H strains by the addition of H2O2 (p<0.05). Infection with live bacteria and ROS generated by DHR-labeled strains showed a higher fitness of LAM strains to enter PMN. Conclusion: these differences in Mtb up-take and ROS production among strains may determine the PMN activation/apoptosis fate and explain the characteristic innate immune response of each strain