SLAMF1 participates in Mycobacterium tuberculosis uptake by human monocyte-derived macrophages

BARBERO ANGELA MARIA; HERNANDEZ DEL PINO RODRIGO EMANUEL; TROTTA ALDANA; GENOULA MELANIE; ESTERMANN MARTIN; CELANO JOSEFINA; FUENTES FEDERICO; VERONICA EDITH GARCIA; BALBOA LUCIANA; BARRIONUEVO PAULA; PASQUINELLI VIRGINIA

Simposio; Innate Immunity: Mechanisms and Modulation. Keystone Symposium; 2021

Since 2016, Tuberculosis has been considered the leading cause of death by a single infectious agent in the world, rising above HIV/AIDS. Mycobacterium tuberculosis has evolved over ages and has managed to evade the immune system, surviving within host macrophages. The costimulatory molecule SLAMF1 (Signaling Lymphocytic Activation Molecule Family member 1) is a self-ligand receptor that can internalize Gram-negative bacteria and regulate phagosomal functions in macrophages. In Tuberculosis, SLAMF1 promotes Th1 protective immune responses. Here, we studied the role of SLAMF1 on macrophages? functions against M. tuberculosis infection.Human monocyte-derived macrophages were obtained from healthy donors (HD) by CD14 positive selection. After 2h of adherence, cells were cultured in complete media overnight before stimulation with sonicated-M. tuberculosis (Mtb). THP-1 cells were differentiated with PMA for 24h before Mtb stimulation. Cells from Tuberculosis patients were also evaluated.SLAMF1 expression was increased in monocyte-derived macrophages from HD and THP-1 cells stimulated with Mtb, as determined by flow cytometry (FC) and confocal microscopy (CM). While rhIFN- stimulation also induced SLAMF1 expression, no changes were observed with rhIL-4 or rhIL-10 treatment. Experiments with conditioned media indicated that SLAMF1 expression is up-regulated on the cells that are interacting with Mtb and is not the result of a bystander effect. Notably, higher SLAMF1 levels were detected in CD14 positive cells from pleural effusions compared to peripheral blood CD14 positive cells from Tuberculosis patients, indicating a possible active function of SLAMF1 at the site of infection.SLAMF1 activation did not regulate TNF-α nor IL-1β production as measured by ELISA but it did stimulate macrophages-Mtb interaction. Costimulation trough SLAMF1 with an agonistic antibody further induced Mtb-Rodamine and lived M. tuberculosis-RFP endocytosis by macrophages and THP-1 cells. Additionally, we obtained biochemical proof of SLAMF1 directly interacting with Mtb by FC and fluorescence microscopy. Furthermore, we found that SLAMF1 colocalized with Mtb (Manders? index (MI) of 0.74) and with early (EEA1) and late (LAMP2) endosomes/lysosomes markers by CM (MI of 0.6 and 0.7, respectively). Taken together, our results show that SLAMF1 mediates Mycobacterium tuberculosis recognition and endolysosomal maturation in human monocyte-derived macrophages