AZITHROMYCIN DISTINCTIVELY AFFECTS MESENTERIC LYMPH NODE CELL PHENOTYPE AND FOXP3 INDUCTION AFTER IN VITRO STIMULATION WITH BACTERIAL EXTRACTS

VIRGINIA, PIQUERAS; LUCIANA, MOINE; CRISTIAN, JAIME; SILVIA, CORREA

Mar del Plata

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2022; 2022

The gut microbiota plays a crucial role in influencing the development of host immunity. Most studies of the microbiome to date have focused on analyzing the organization of the microbial population. However, it is equally important to study how variability in microbial abundance and composition affects host functions. We previously described significant changes in microbial abundance in mice treated for 5 days in drinking water with 50 mg/kg/day of azithromycin (AZM), an antibiotic of the macrolide family. In this work, using C57BL/6 GFP-Foxp3 mice, we evaluated whether differences in microbial composition could modify cellular subsets of inductive sites in the intestinal mucosa. For this we prepared a) bacterial extracts (BE) and b) filtered bacterial extracts (f) from fecal samples from the control group (BEC and BECf) and from the AZM group after 5 days of treatment (BEA and BEAf). Mononuclear cells from mesenteric lymph nodes (MLN) draining small intestine (SI) and colon (C) from control and AZM-treated groups were cultured for 24 h with PBS (basal condition), BEC, BECf, BEA and BEAF. After stimulation, we determined the frequency (%) and mean fluorescence intensity (MFI) of CD3+, CD4+, CD4+Foxp3+, CD4+CD49b+, CD8+, and CD19+ lymphoid subsets by flow cytometry. The % of SI CD4+Foxp3+ cells increased in the AZM group both in basal cultures (p=0.0385) and after BEC (p=0.0022). The increase in the % of CD4+Foxp3+ cells was dependent on the presence of bacteria in the AZM group (p