title: Group B streptococcal infection of the choriodecidua induces dysfunction of the cytokeratin network in amniotic epithelium: a pathway to membrane weakening.
abstract: Early events leading to intrauterine infection remain poorly defined, but may hold the key to preventing preterm delivery. To determine molecular pathways within fetal membranes (chorioamnion) associated with early choriodecidual infection that may progress to preterm premature rupture of membranes (PPROM), we examined the effects of a Group B Streptococcus (GBS) choriodecidual infection on chorioamnion in a nonhuman primate model. Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term = 172 days) received choriodecidual inoculation of either GBS (n = 5) or saline (n = 5). Cesarean section was performed in the first week after GBS or saline inoculation. RNA extracted from chorioamnion (inoculation site) was profiled by microarray. Single gene, Gene Set, and Ingenuity Pathway Analysis results were validated using qRT-PCR (chorioamnion), Luminex (amniotic fluid, AF), immunohistochemistry, and transmission electron microscopy (TEM). Despite uterine quiescence in most cases, significant elevations of AF cytokines (TNF-α, IL-8, IL-1β, IL-6) were detected in GBS versus controls (p<0.05). Choriodecidual infection resolved by the time of cesarean section in 3 of 5 cases and GBS was undetectable by culture and PCR in the AF. A total of 331 genes were differentially expressed (>2-fold change, p<0.05). Remarkably, GBS exposure was associated with significantly downregulated expression of multiple cytokeratin (CK) and other cytoskeletal genes critical for maintenance of tissue tensile strength. Immunofluorescence revealed highly significant changes in the CK network within amniocytes with dense CK aggregates and retraction from the cell periphery (all p = 0.006). In human pregnancies affected by PPROM, there was further evidence of CK network retraction with significantly shorter amniocyte foot processes (p = 0.002). These results suggest early choriodecidual infection results in decreased cellular membrane integrity and tensile strength via dysfunction of CK networks. Downregulation of CK expression and perturbations in the amniotic epithelial cell intermediate filament network occur after GBS choriodecidual infection, which may contribute to PPROM.
authors.affiliation: Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Jeroen P
authors.initials: JP
authors.lastname: Vanderhoeven
authors.affiliation: Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Bierle
authors.affiliation: Departments of Pathology, Seattle Children's and University of Washington, Seattle, Washington, United States of America.
authors.forename: Raj P
authors.initials: RP
authors.lastname: Kapur
authors.affiliation: Department of Pediatrics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: McAdams
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Beyer
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Theo K
authors.initials: TK
authors.lastname: Bammler
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Federico M
authors.initials: FM
authors.lastname: Farin
authors.affiliation: Department of Biostatistics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Aasthaa
authors.initials: A
authors.lastname: Bansal
authors.affiliation: Center on Human Development and Disability, University of Washington, Seattle, Washington, United States of America.
authors.forename: Min
authors.initials: M
authors.lastname: Spencer
authors.affiliation: Center on Human Development and Disability, University of Washington, Seattle, Washington, United States of America.
authors.forename: Mei
authors.initials: M
authors.lastname: Deng
authors.affiliation: Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington, United States of America; Global Alliance to Prevent Prematurity & Stillbirth, Seattle, Washington, United States of America.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gravett
authors.affiliation: Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America; Department of Pediatrics, University of Washington, Seattle, Washington, United States of America; Global Alliance to Prevent Prematurity & Stillbirth, Seattle, Washington, United States of America.
authors.forename: Craig E
authors.initials: CE
authors.lastname: Rubens
authors.affiliation: Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America; Department of Pediatrics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Rajagopal
authors.affiliation: Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington, United States of America; Center on Human Development and Disability, University of Washington, Seattle, Washington, United States of America.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Adams Waldorf
mesh_terms: D000650:Amnion / Q000382:microbiology / Q000473:pathology*; D000818:Animals; D002823:Chorion / Q000382:microbiology / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000235:genetics / Q000382:microbiology / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism*; D008254:Macaca nemestrina; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000235:genetics / Q000382:microbiology / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000235:genetics / Q000473:pathology*; D013292:Streptococcus agalactiae; D059467:Transcriptome
chemical_list: D007633:Keratins