537: Immunoglobulins (IgA) target bacteria in the breast milk and infant gut microbiomes

Abstract

OBJECTIVE: Chorioamniotic membrane senescence mediated by p38 mitogen activated kinase (p38 MAPK) in response to oxidative stress (OS) is associated with human parturition. In vivo, term labor fetal membranes showed OS, p38 MAPK activation, senescence and senescence associated inflammation. These findings are recapitulated in vitro in primary amnion epithelial cells (AECs) from term not in labor membranes exposed to OS induced by cigarette smoke extract (CSE). Our objective was to determine p38 induced senescence activation in response to other pathologic (LPS -infection; TNF-ainflammation) signals associated with preterm birth. STUDY DESIGN: AECs from fetal amniotic membranes at term, not in labor were exposed to tumor necrosis factor-alpha (TNF-a 50ng/mL) and lipopolysaccharide (LPS 100ng/mL) for 30 minutes or one hour. CSE (1:10) was used as positive control. Western blot analysis was performed for active and total p38 MAPK followed by densitometric analysis. Senescence was determined by flow cytometry using 5-Dodecanoylaminofluorescein di-b-D-galactopyranoside (C 12 FDG), a fluorogenic substrate for senescence associated b-galactosidase (SA-b-gal). Data were confirmed by cytological evaluation. Analysis was performed using the Mann-Whitney U test. RESULTS: p38 MAPK activation was increased in cells treated with TNF-a and CSE, but not LPS compared to untreated cells (control)(p¼0.04, p¼0.007 , p¼0.56 respectively; Figure A). The number of senescent cells as detected by C 12 FDG fluorescence were increased by all stimulants compared to control cells (p<0.05; Figure C). Senescence was confirmed with cytologic staining (Figure B). CONCLUSION: TNF-a, an inflammatory cytokine produced in response to various preterm birth-associated risk factors, and CSE induced senescence of AECs through the p38 MAPK pathway. LPS induction of senescence was independent of the p38MAPK pathway. Infectious and inflammatory factors may cause premature fetal cell senescence contributing to preterm birth pathophysiology.