Objectives: This study aimed to compare the serum IL-22 levels between preterm premature rupture of membranes (PPROM) patients and the control group with intact membranes. We also hypothesized whether serum IL-22 upregulation might contribute to defense against inflammatory responses and improve the pregnancy outcomes.
Material and methods: We performed this prospective case-control study between 24-34 weeks of pregnancy. We enrolled 40 singleton pregnant patients with PPROM and 40 healthy gestational age- and gravidity-matched patients without PPROM. The degree of association between variables and IL-22 were calculated by Spearman correlation coefficients where appropriate. Scatter plots were given for statistically significant correlations. ROC curve was constructed to illustrate the sensitivity and specificity performance characteristics of IL-22, and a cutoff value was estimated by using the index of Youden.
Results: Maternal serum IL-22 levels were significantly higher in PPROM patients (60.34 ± 139.81 pg/mL) compared to the participants in the control group (20.71 ± 4.36 pg/mL, p < 0.001). When we analyze the area under the ROC curve (AUC), the IL-22 value can be considered a statistically significant parameter for diagnosing PPROM. According to the Youden index, a 23.86 pg/mL cut-off value of IL-22 can be used to diagnosing PPROM with 72% sensitivity and 61.5% specificity. There was no positive correlation between serum IL-22 levels and maternal C-reactive protein (CRP) value, procalcitonin value, latency period, birth week, birth weight, and umbilical cord blood pH value.
Conclusions: Maternal serum IL-22 levels were significantly higher in PPROM patients than healthy pregnant women with an intact membrane. We suggest that IL-22 might be a crucial biomarker of the inflammatory process in PPROM.
Keywords: interleukin-22; neonatal outcomes; preterm premature rupture of membranes.