Salivary cytokine — A non-invasive predictor for bronchopulmonary dysplasia in premature neonates

Background: To find a less invasive method of cytokine detection for premature neonates, we conducted this cohort study to investigate the salivary cytokines and to analyze their correlations with bronchopulmonary dysplasia (BPD). Methods: Premature neonates younger than 34 weeks of gestational age without maternal or neonatal infection were recruited. Salivary samples were collected on their first (D1) and seventh (D7) days of life. The cytokine levels were detected by MILLPLEX® MAP Human multiplex assay. One-way analysis of variance, the Kruskal-Wallis test, Pearson's chi-square test, and logistic regression were used to analyze the data. Results: Totally 125 neonates were enrolled and separated into four groups: control, mild, moderate, and severe BPD group. The salivary levels of D1 interleukin (IL)-6, IL-8, IL-10, IL-17, interferon (IFN)-γ, and D7 IL-6 (p = 0.001, 0.001, 0.000, 0.043, 0.037 and 0.001, respectively) were significantly higher in the BPD groups than in the control group. After adjusting for the gestational age, acid-base equivalent, and absolute neutrophil count, comparing to the control group, the levels of D7 IL-17 became significantly lower in all three BPD groups (p = 0.032, 0.030, and 0.030, respectively) and that of D7 IFN-α2 became significantly lower in the severe BPD group (p = 0.037). Conclusion: Early-life salivary cytokine levels were correlated with the development of BPD in premature neonates. This study provides a novel method to predict BPD early and non-invasively.