Interleukin-6 pathobiology in equine placental infection

Carleigh E. Fedorka, Kirsten E. Scoggin, Hossam El-Sheikh Ali, Shavahn C. Loux, Pouya Dini, Mats H.T. Troedsson, Barry A. Ball

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Problem: Ascending placentitis is the leading cause of abortion in the horse. Interleukin (IL)-6 is considered predictive of placental infection in other species, but little is understood regarding its role in the pathophysiology of ascending placentitis. Method of study: Sub-acute ascending placentitis was induced via trans-cervical inoculation of S zooepidemicus, and various fluids/serum/tissues collected 8 days later. Concentrations of IL-6 were detected within fetal fluids and serum in inoculated (n = 6) and control (n = 6) mares. RNASeq was performed on the placenta (endometrium and chorioallantois) to assess transcripts relating to IL-6 pathways. IHC was performed for immunolocalization of IL-6 receptor (IL-6R) in the placenta. Results: IL-6 concentrations increased in allantoic fluid following inoculation, with a trend toward an increase in amniotic fluid. Maternal serum IL-6 was increased in inoculated animals, while no changes were noted in fetal serum. mRNA expression of IL-6-related transcripts within the chorioallantois indicates that IL-6 is activating the classical JAK/STAT pathway, thereby acting as anti-inflammatory, anti-apoptotic, and pro-survival. The IL-6R was expressed within the chorioallantois, indicating a paracrine signaling pathway of maternal IL-6 to fetal IL-6R. Conclusion: IL-6 plays a crucial role in the placental response to induction of sub-acute equine ascending placentitis, and this could be noted in amniotic fluid, allantoic fluid, and maternal serum. Additionally, IL-6 is acting as anti-inflammatory in this disease, potentially altering disease progression, impeding abortion signals, and assisting with the production of a viable neonate.

Original languageEnglish
Article numbere13363
JournalAmerican Journal of Reproductive Immunology
Issue number5
StatePublished - May 2021

Bibliographical note

Funding Information:
This study was funded by the Albert G. Clay Endowment at the University of Kentucky.

Publisher Copyright:
© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd


  • IL-6
  • cytokine
  • equine
  • infectious abortion
  • placentitis

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Reproductive Medicine
  • Obstetrics and Gynecology


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