ALVEOLAR MACROPHAGES DEPLETION AFFECTS THE ABILITY OF DOLOSIGRANULUM PIGRUM 040417 TO PROTECT INFANT MICE AGAINST PNEUMOCOCCAL INFECTION

RAYA TONETTI, FERNANDA; ORTIZ MOYANO, RAMIRO; TOMOKIYO, MIKADO; VYACHESLAV MELNIKOV; KITAZAWA, HARUKI; VILLENA, JULIO

Congreso; Reunión Anual de Sociedades de Biociencias 2021; 2021

Previously, we demonstrated that the nasal administration of the respiratory commensal bacterium Dolosigranulum pigrum 040417 (Dp04) to infant mice differentially modulates the respiratory immune response triggered by Toll-like receptor (TLR)-2 activation, increasing the resistance to Streptococcus pneumoniae (Sp) infection. The nasal priming with Dp04 reduced pneumococcal counts in lung and blood and diminished the levels of lung injury biomarkers. In this work, we aimed to characterize the role of alveolar macrophages (AM) on the immunomodulatory properties of Dp04 in the context of pneumococcal infection. In the first set of experiments, mice were nasally stimulated with Dp04 (108 cells/mouse/day) for 5 consecutive days and then challenged with 106 CFU of Sp. Variations in numbers and functionality of resident AM in broncho-alveolar lavage (BAL) samples were evaluated. The number of activated CD11c+SiglecF+MHC-IIhi AM was significantly increased after Sp challenge in mice primed with Dp04 than in controls (p