Tandem Mass Tag-Labeled Quantitative Proteome Analyses Identify C1R and A2M as Novel Serum Biomarkers in Pregnant Women with Obstructive Sleep Apnea

The aim of this study was to identify serum diagnostic biomarkers associated with the severity of obstructive sleep apnea (OSA) during pregnancy. Differentially expressed proteins (DEPs) were identified in the control (C), mild (O), and moderate (MO) OSA groups (n = 3 in each group). Bioinformatics analysis was conducted to identify the underlying functions, pathways, and networks of the proteins. Receiver operating characteristic curves were used to assess the diagnostic value of the identified DEPs. The enzyme-linked immunoassay was performed to detect serum levels of the complement C1r subcomponent (C1R) and alpha-2-macroglobulin (A2M) in 79 pregnant women with OSA (mild OSA [n = 32]; moderate OSA [n = 29], and severe OSA [n = 18]) and 65 healthy pregnant women without OSA. Pearson’s correlation analysis was conducted to analyze the correlation between C1R and A2M levels and OSA clinicopathological factors. In total, 141 DEPs, 29 DEPs, and 103 DEPs were identified in the three groups (i.e., the mild OSA vs control group, the moderate OSA vs mild apnea group, and the moderate OSA vs control group, respectively). C1R and A2M were identified as continuously up-regulated proteins, and the levels of C1R and A2M were associated with OSA severity. C1R and A2M were found to be correlated with body mass index, systolic blood pressure, apnea–hypopnea index, oxygen desaturation index, time with saturation below 90%, and lowest SaO₂. Adverse maternal and neonatal outcomes were observed in pregnant women with OSA. C1R and A2M have been identified as diagnostic biomarkers and are associated with the severity of OSA during pregnancy.