High Mobility Group Box 1 in experimental tuberculosis.

HERNANDEZ PANDO R; BARRIOS PAYAN J; MATA ESPINOSA D; MARQUINA CASTILLO B; HERNANDEZ RAMIREZ D; BOTTASSO O; BINI E

Medellín

Congreso; 11th Congress of the Latin American Association of Immunology (ALAI). Medellin 13-16 Octubre 2015; 2015

Sociedad Latinoamericana de Inmunología

The high mobility group box 1 (HMGB1) is the prototype of alarmin protein released by stressed or dying cells that regulates the inflammatory response (1). It can be modified into three isoforms,depending on the redox state of its cysteines. It can act as a chemotactic mediator, it can stimulate leukocyte recruitment, or it can have no chemokine or cytokine activities (2,3). Different cells are involved in the release ofthe different isoforms: necrotic, apoptotic, stressed cells. Considering thepresence of these cells along the course of the TB, the contribution of HMGB1 in the immunopathology of TB could be important. Our study aimed at evaluating the kinetics, cellular sources and function of HMGB1 in a model of pulmonary TB in BALB/c mice. The present work was carried out in male BALB/c mice, 6-8 weeks old, infected with 2x105 live bacilli Mycobacterium tuberculosis strain H37Rv.At different time points, HMGB1 was quantified in bronchial lavage fluid (BALF)by ELISA and the determination of reduced or oxidized HMGB1 was performed by western blotting. In lungs, its cellular sources were determined by immunohistochemistry, and the presence and release from a bronchialepithelial cell was detected by immunoelectronmicroscopy micrograph. In another group of infected mice, HMGB1 was blocked with chicken Anti-HMGB1 PolyclonalAntibody, and another one received human recombinant HMGB1 during early infection.The same experiments were carried out during the late infection. Bacilli burdens, inflammation (by morphometry using an image analyser) and cytokinesexpression of TNFalpha , IFN gamma, IL10 and IL17 (by RT-PCR) were determined. Control groups consisted in uninfected mice, and a group receiving IgY from chicken. For the statistical analysis, data were presented as the mean +/-standard deviation. Differences among groups were evaluated by the Anova test,whereas the Student t test was used for further analysis among group differences. An associated probability lower than 0.05, was consideredsignificant. As result, the maximal concentration of HMGB1 in BALF was at dayone of infection. Bronchial epithelium and macrophages were the most important sources. At day 7 to 21 the oxidized HMGB1 was predominant, while during late infection only the reduced form was seen. Blocking HMGB1 during early infection produced significant decrease of bacilli burdens and high production of pro-inflammatory cytokines, while the opposite was seen when HMGB1 was administered. Blocking HMGB1 activity or administrated it in high amounts during late infection worsening the disease In conclusion, HMGB1 is liberated during experimental tuberculosis and promotes or suppress the immune response and inflammation depending on the redox state.