ORIGINAL ARTICLE: CXCL6 (Granulocyte Chemotactic Protein‐2): A Novel Chemokine Involved in the Innate Immune Response of the Amniotic Cavity

Abstract

Problem CXCL6 is a potent pro‐inflammatory neutrophil chemoattractant and activator whose activity during pregnancy is not well‐established. The purpose of this study was to determine if CXCL6 is present in amniotic fluid (AF) and if CXCL6 concentrations in AF change with labor (pre‐term and term) or intra‐amniotic infection/inflammation (IAI).Method of study A cross‐sectional study was designed including the following groups: (1) mid‐trimester (n = 65); (2) term no labor (n = 20); (3) term labor (n = 44); (4) patients with pre‐term labor (PTL) with subsequent term delivery (n = 57); (5) PTL without IAI who delivered pre‐term (n = 47); and (6) PTL with IAI (n = 62). AF CXCL6 concentrations were determined by ELISA.Results CXCL6 was present in all term samples, but undetectable in 64/65 mid‐trimester specimens. Patients with PTL and IAI had a significantly higher median AF CXCL6 concentration than those with PTL without IAI [228.9 pg/mL (0.0–8344.8) versus 55.7 pg/mL (0–454.4); P < 0.05] and those with PTL and term delivery [41.5 pg/mL (0–279.0); P < 0.05]. The median AF CXCL6 concentration did not change with spontaneous term labor [term no labor: 81.1 pg/mL (8.5–201.7) versus term labor: 75.2 pg/mL (6.7–378.7): P = 0.7].Conclusion (1) CXCL6 is detectable in AF and its concentration increases with gestational age; (2) IAI results in increased AF CXCL6 concentrations, suggesting that CXCL6 plays a role in the deployment of an inflammatory response; (3) In contrast to related chemokines, specifically IL‐8, AF CXCL6 does not appear to be involved in spontaneous term parturition. These observations are novel, and suggest a role for CXCL6 in the innate immune response to microbial invasion of the amniotic cavity.