Elevated human placental heat shock protein 5 is associated with spontaneous preterm birth

Abstract

AbstractBackgroundSpecific heat shock proteins are associated with pregnancy complications, including spontaneous preterm birth (SPTB). Placental proteomics and whole exome sequencing recently suggested an association between heat shock protein HSPA5 and uncomplicated SPTB. In the present study, we investigated the localization of and possible roles for HSPA5 in SPTB.MethodsWestern blot was performed to validate the result from the previously published proteomic analysis. We used qPCR to assess mRNA expression of genes and immunohistochemistry and immunoelectron microscopy to examine localization of HSPA5 in placental tissue. We silenced theHSPA5gene in the HTR8/SVneo human trophoblast cell line to investigate possible functions of HSPA5.ResultsHSPA5 was upregulated in placentas from SPTBs compared to spontaneous term births. We did not observe upregulation ofHSPA5mRNA in placental samples. The protein was localized in placental trophoblast in both spontaneous preterm and term placentas. Gene silencing ofHSPA5in human trophoblast cell culture affected the inflammatory response and decreased the expression of several proinflammatory genes.ConclusionsWe suggest that upregulation of HSPA5 in the placenta is associated with spontaneous preterm labor. HSPA5 may promote the inflammatory response and alter the anti-inflammatory state of the placenta which could eventually lead to premature labor.ImpactWe validated upregulation of HSPA5 in placentas from spontaneous preterm birth.HSPA5was not upregulated at transcriptional level which suggests that it may be regulated post-translationally.SilencingHSPA5in a human trophoblast–derived cell line suggested that HSPA5 promotes expression of proinflammatory cytokines. The emerging inflammation could lead to spontaneous preterm labor.Identifying inflammatory pathways and factors associated with spontaneous preterm birth increases knowledge of the molecular mechanisms of premature labor. This could provide cues to predict imminent premature labor and lead to information about how to safely maintain pregnancies.