Association of Placental Tissue S100A14 Expression with Histologic Chorioamnionitis in Preterm Birth

Background/Objectives: S100A14 has been implicated in cellular signaling and tissue remodeling, but its relationship with histologic chorioamnionitis (HCA) remains unknown. We evaluated its placental expression and discriminatory performance for HCA in preterm birth. Methods: This retrospective cohort included 233 women with singleton spontaneous preterm births. Placental tissues were evaluated by immunohistochemistry for S100A14, MMP-2, ERK, and p38. Expression was compared by HCA status, and correlations were evaluated using Spearman coefficients. Multivariable logistic regression was adjusted for gestational age at delivery and preterm prelabor rupture of membranes (PPROM) status. Discriminatory performance was assessed using receiver operating characteristic analysis. Results: S100A14 scores were higher in placentas with HCA than without HCA (5.61 vs. 2.97, p < 0.001) and remained independently associated with HCA after adjustment (adjusted odds ratio per 1-point increase, 1.50; 95% confidence interval, 1.31–1.71; p < 0.001). MMP-2 expression was also elevated in HCA, whereas ERK and p38 expression did not differ by HCA status. S100A14 correlated most strongly with MMP-2 (ρ = 0.531, p < 0.001). Among 173 participants with complete data, the areas under the curve were 0.780 for placental S100A14, 0.717 for placental MMP-2, and 0.660 for maternal serum CRP at admission; the difference between S100A14 and CRP was statistically significant (p = 0.023), whereas the difference between S100A14 and MMP-2 was not (p = 0.126). At an optimal cutoff of 5.0, sensitivity was 55.2% and specificity was 80.2%. Conclusions: Placental S100A14 expression was independently associated with HCA and showed moderate tissue-level discriminatory ability for HCA. Its modest sensitivity limits its utility as a stand-alone diagnostic marker. Further studies are required to determine whether S100A14 or related molecular signals can be detected and validated in specimens obtainable before delivery.