Fig. 1

Workflow of the present study. The starting point of this study was to determine proteomes from spontaneous preterm (SPTB), spontaneous term, and elective preterm human placentas to identify proteins potentially in association with SPTB. When we compared the proteomic findings with whole exome sequencing (WES) data from SPTB families, AAT/SERPINA1 emerged as a candidate. To verify our findings and to explore the location and function of AAT/SERPINA1 in placentas of SPTB, we performed experiments on placental samples and placenta-associated cells. The placenta samples on which the proteomics were performed were also included in the following analyses. Only in immuno-EM and immunofluorescence microscopy, the placenta samples were different. N is number of samples, FIN is Finland, and DK is Denmark. *Finnish WES; 17 mothers and their 23 children. Danish WES; n = 93 sister pairs and two families with three affected siblings