title: Systematic identification of spontaneous preterm birth-associated RNA transcripts in maternal plasma.
abstract: BACKGROUND
  Spontaneous preterm birth (SPB, before 37 gestational weeks) is a major cause of perinatal mortality and morbidity, but its pathogenesis remains unclear. Studies on SPB have been hampered by the limited availability of markers for SPB in predelivery clinical samples that can be easily compared with gestational age-matched normal controls. We hypothesize that SPB involves aberrant placental RNA expression, and that such RNA transcripts can be detected in predelivery maternal plasma samples, which can be compared with gestational age-matched controls.
  
  
  RESULTS
  Using gene expression microarray to profile essentially all human genes, we observed that 426 probe signals were changed by >2.9-fold in the SPB placentas, compared with the spontaneous term birth (STB) placentas. Among the genes represented by those probes, we observed an over-representation of functions in RNA stabilization, extracellular matrix binding, and acute inflammatory response. Using RT-quantitative PCR, we observed differences in the RNA concentrations of certain genes only between the SPB and STB placentas, but not between the STB and term elective cesarean delivery placentas. Notably, 36 RNA transcripts were observed at placental microarray signals higher than a threshold, which indicated the possibility of their detection in maternal plasma. Among them, the IL1RL1 mRNA was tested in plasma samples taken from 37 women. It was detected in 6 of 10 (60%) plasma samples collected during the presentation of preterm labor (≤32.9 weeks) in women eventually giving SPB, but was detected in only 1 of 27 (4%) samples collected during matched gestational weeks from women with no preterm labor (Fisher exact test, p = 0.00056).
  
  
  CONCLUSIONS
  We have identified 36 SPB-associated RNA transcripts, which are possibly detectable in maternal plasma. We have illustrated that the IL1RL1 mRNA was more frequently detected in predelivery maternal plasma samples collected from women resulting in SPB than the gestational-age matched controls.
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China. sschim@cuhk.edu.hk
authors.forename: Stephen S C
authors.initials: SS
authors.lastname: Chim
authors.forename: Wing S
authors.initials: WS
authors.lastname: Lee
authors.forename: Yuen H
authors.initials: YH
authors.lastname: Ting
authors.forename: Oi K
authors.initials: OK
authors.lastname: Chan
authors.forename: Shara W Y
authors.initials: SW
authors.lastname: Lee
authors.forename: Tak Y
authors.initials: TY
authors.lastname: Leung
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D002585:Cesarean Section; D005260:Female; D020869:Gene Expression Profiling; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000235:genetics*; D008423:Maternal Age; D007752:Obstetric Labor, Premature / Q000097:blood / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D011248:Pregnancy Complications / Q000235:genetics*; D047928:Premature Birth / Q000097:blood / Q000235:genetics*; D012313:RNA / Q000097:blood* / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D012313:RNA