Structural alterations of human chorioamniotic membranes treated with α-hemolysin of E.coli

MELISA PUCCI MOLINERIS; MARÍA SILVIA LIMA; PABLO PELINSKI; HUGO BARBERO; MARIANA FARINA; VANESA HERLAX

Congreso; Reunion anual de Sociedades de Biociencias; 2020

α-hemolysin (HlyA), toxin secreted by uropathogenic strains of Escherichia coli (E.coli), has a fundamental role in urinary tract infections (UTIs). In pregnancy, UTIs are very frequent, being E. coli the etiological agent of almost the 80% of the cases. Considering that UTIs are related with premature rupture of fetal membranes, we proposed to analyze structural tissue changes of human chorioamniotic membranes treated with different concentrations of HlyA in vitro Methods: Chorioamniotic membranes (n=6) were obtained from deliveries by elective cesarean section (>37 weeks). All included women had uneventful (normal?) pregnancies, without evidence of active labor and with no infection signs . Membrane explants were mounted and insured to a Transwell device to generate two independent chambers. To simulate an ascending infection, explants were incubated ? in the chorion-side, with 5nM/50nM HlyA ?purified from WAM1824 E.coli culture during 24h. HlyA was detected by immunohistochemistry and histological signs of damage (like edema, vacuolization, early and late apoptosis, extracellular matrix thickness, and number of fibroblast) were evaluated from paraffin-embedded tissue sections stained with hematoxylin/eosin . Necrosis was tested by LDH release and the transepithelial electrical resistance (TEER) was measured using a Millicell-ERS unit (n=3). Groups were compared in pairs using t- or U Mann-Whitney test as correspond.Results: HlyA interaction with chorioamniotic membranes, from chorion-side, caused structural alterations and a slight diminish of TEER after 24hs of toxin incubation. The main tissue alteration were observed for the highest toxin concentration tested (50nM HlyA) Epithelial layer remained practically unaltered, while chorion cells showed an increment of vacuolization and necrosis . Extracellular matrix thickness was higher and fibroblast number lower in treated groups compared to control ones. Conclusion: HlyA altered the integrity of chorioamniotic membrane contributing probably to premature rupture of these membranes , an unwanted effects of UTIs in pregnancy.