Intestinal microbiota modulates the neutrophil homeostasis through a mechanism involving TNFR

BIANCA GHIDELLA CHIESA ; MARIANELA LEPORATI; SILVIA DI GENARO; JAVIER ELIÇABE

San Luis

Congreso; LXXI Reunión Anual de la Sociedad Argentina de Inmunología; 2023

Neutrophils are the first leukocytes to be recruited to an inflammatory site and arecapable of eliminating pathogens. These cells are continuously generated in thebone marrow (BM) from hematopoietic stem cells. Cytokines and microbiotaderived components play important roles in the granulopoiesis. The purpose ofthis work was to investigate the role of TNFR1 in neutrophil homeostasis and theinfluence of the microbiota. Naïve C57BL/6 wild-type (WT) or TNFR1 knockout(TNFR1-/-) mice were treated with an antibiotic (ABX) cocktail, consisting ofampicillin, neomycin, metronidazole and vancomycin in drinking water to inducemicrobiota depletion. In addition, microbiota-depleted WT and TNFR1-/- micewere infected with Yersinia enterocolitica (Ye) serotype O:3. Neutrophil frequencywas analyzed by flow cytometry in bone marrow (BM), peripheral blood (PB),spleen and mesenteric lymph nodes (MLN) of naïve and infected mice. Ourresults show that the absence of TNFR1 does not affect the hematopoiesis andgranulopoiesis in particular. However, TNFR1-deficient mice showed a markedincrease in leukocytes, particularly in thefrequency and the number of neutrophilsin SP compared to WT mice (p