Serum MGP and ECP are commonly elevated in first-onset and recurrent ischemic stroke: a two-phase DIA proteomic study in a Chinese cold-region cohort

Background Ischemic stroke (IS) has a high recurrence rate, yet effective biomarkers for distinguishing first-onset from recurrent IS remain limited. This study aimed to identify serum proteomic biomarkers commonly elevated in both first-onset and recurrent IS and to evaluate their ability to discriminate each disease state from healthy controls in a Chinese cold-region population. Methods The study was conducted in two phases. In the discovery phase, 10 patients with first-onset IS, 10 with recurrent IS, and 10 healthy controls were analyzed using Data-Independent Acquisition (DIA) proteomics; the validation phase expanded the sample to 49 patients with first-onset IS, 30 with recurrent IS, and 50 healthy controls. Differentially expressed proteins were defined as fold change≥1.5 or ≤0.67. Multivariable Firth penalized logistic regression adjusted for age and sex constructed diagnostic models, with data randomly split into training and test sets (2:1) for receiver operating characteristic (ROC) analysis. Results Two core proteins were identified: matrix Gla protein (MGP) and eosinophil cationic protein (ECP). Both were significantly elevated in the first-onset and recurrent IS groups compared with healthy controls (all p < 0.05). Two separate logistic models incorporating these proteins discriminated first-onset IS (test-set AUC 0.993) and recurrent IS (test-set AUC 0.959) from healthy controls, confirmed by repeated 10-fold cross-validation; the two proteins did not differ significantly between the patient groups. Enrichment analysis of their interaction partners revealed involvement in neutrophil extracellular trap formation, inflammatory responses, and immune regulation. Conclusion Serum MGP and ECP were commonly elevated in both first-onset and recurrent IS, and two separate combinatorial models discriminated each disease state from healthy controls with high accuracy. This biomarker panel covers three core pathological processes-atherosclerosis and vascular calcification, chronic inflammation, and hypercoagulable state-providing candidate biomarkers that warrant further investigation for disease-state characterization and risk stratification, particularly in high-latitude cold-region populations.