STUDY OF THE INTESTINAL MUCOSAL INNATE IMMUNE RESPONSE IN A MOUSE MODEL OF HEMOLYTIC UREMIC SYNDROME (HUS) BY INTRAGASTRICAL INOCULATION OF SHIGA TOXIN-PRODUCING ESCHERICHIA COLI (STEC)

BRUBALLA, ANDREA CECILIA; PALERMO, MARINA SANDRA; PINEDA, GONZALO EZEQUIEL; FERNÁNDEZ BRANDO, ROMINA JIMENA; MARÍA VICTORIA RAMOS

Mar del Plata

Congreso; SAIC-SAI-SAFIS 2018; 2018

SAIC-SAI-SAFIS

HemolyticUremic Syndrome (HUS) is the most serious, life-threatening complicationfollowing Shiga toxin-producing Escherichia coli (STEC) infections and ischaracterized by microangiopathic hemolytic anemia, thrombocytopenia and renaldysfunction. Given that the innate immune response in the gut is the firstbarrier encountered by bacteria in these infections, in the present work weaimed at characterizing it in a mouse model of HUS. C57Bl/6 mice at weaningwere intragastrically inoculated with a human-isolated STEC strain (125/99) orits isogenic strain defective in Stx production (ΔStx). As a control mice wereinoculated with PBS (C). Four hours later mice were killed and leukocytes from mesentericlymph nodes (MLN) and lamina propria (LP) were isolated. We assessed cytokineproduction (IL-4,-5, -6, -10, -17, TGF-β) from leukocytes stimulated in vitro withanti-CD3 and -CD28 antibodies, and the relative and absolute number of CD45,CD11b, Ly6G and Siglec-F positive cells from LP by flow cytometry. IL-6 was theonly increased cytokine on culture supernatants from MLN leukocytes of miceinfected with both bacterial strains ([mean±SEM pg/ml]=C:16±2, ΔStx:41±3, 125/99: 44±7, ANOVA p<0.01, SNKp<0.01). Besides, we observed an increased absolute number of CD45+CD11b+leukocytes from the LP from infected mice compared to control([104 leukocytes]=C:1.15, ΔStx:1.80, 125/99: 2.05; two-way ANOVAp<0.05, Bonferroni p<0.05), and also an increased absolute and relativenumber of CD45+CD11b+Ly6G+ leukocytes (([103cells]=C:0.24, ΔStx:0.69, 125/99: 1.36; [%]= C:0.18, ΔStx:0.65, 125/99:1.17) andCD45+CD11b+Siglec-F+ leukocytes (([103 cells]=C:2.00, ΔStx:6.20,125/99: 7.08; [%]= C:46, ΔStx:76, 125/99:71). In conclusion, both bacterialstrains lead to an increased IL-6 production which could account for the influxof CD11b+ cells, Ly6G+ myeloid cells and Siglec-F+ eosinophils into the LP ofinfected mice. Shiga toxin may not induce a differential innate immune responsein the gut, at least on the leukocyte cell subsets studied in the present work.