CONICET | Buscador de Institutos y Recursos Humanos

Neutrophils are part of the first line of immune defense. Neutrophils utilize different mechanisms to protect hosts such us phagocytosis, degranulation and production of neutrophil extracellular trap (NET). NETs are DNA web-like extracellular structures that immobilize and kill bacteria due to the adhesion of antimicrobial proteins. Uncontrolled NETosis, leads to liberation of cell-free DNA and proteases that damage the surrounding cells and exacerbate inflammation. In the gut environment, the presence of beneficial microbes could reduce intestinal inflammation and protect the host. In this work, we investigated the capacity of two lactobacilli strains L. delbrueckii subsp lactis (CIDCA 133) and L. delbrueckii subsp bulgaricus (CIDCA 331) to inhibit NET formation.Human neutrophils were isolated from heparinized venous blood using gradient centrifugation. Cells were incubated with or without lactobacilli at different moi. PMA was used as NET inducer. NETs were visualized by immunofluorescence microscopy. ROS was determined by luminometry. In the absence of stimuli, lactobacilli lacked the ability to induce NETs. However, treatment of neutrophils with lactobacilli (MOI 10) prior to PMA challenge significantly reduced the formation of NETs. Interestingly, strain CIDCA 133 showed a stronger capacity to decrease the number of netotic cells than strain CIDCA 331 (66,09 % ± 3,09 vs 27,69 % ± 0,17, respectively). Lactobacilli showed different capacity to stimulate ROS generation, with strain CIDCA 133 as a strong inducer and strain CIDCA 331 as a non-inducer. Neither of the strains were able to inhibit ROS generation in PMA treated cells. Our results showed that lactobacilli strains had the ability to reduce NET formation but not to dismiss ROS generation in PMA treated cells. NET formation is tightly related to ROS generation and autophagy in PMA induced NETosis. It is possible