Apolipoprotein A-I and paraoxonase-1 are potential blood biomarkers for ischemic stroke diagnosis

Background Blood biomarkers for ischemic and hemorrhagic stroke diagnosis remain elusive. Recent investigations suggested that apolipoprotein (Apo), matrix metalloproteinase (MMP), and paraoxonase-1 may be associated with stroke. We hypothesized that Apo A-I, Apo C-I, Apo C-III, MMP-3, MMP-9, and paraoxonase-1 are differentially expressed in ischemic stroke, hemorrhagic stroke, and controls. Methods In a single-center prospective observational study, consecutive stroke cases were enrolled if blood samples were obtainable within 12 hours of symptom onset. Age- (±5 years), race-, and sex-matched controls were recruited. Multiplex assays were used to measure protein levels. The Wilcoxon signed-rank test and the Mann-Whitney U-test were used to compare biomarker values between ischemic stroke patients and controls, hemorrhagic stroke patients and controls, and ischemic and hemorrhagic stroke patients. The 95% confidence intervals (CIs) for the difference of 2 medians were calculated. Results Fourteen ischemic stroke case-control pairs and 23 intracerebral hemorrhage (ICH) case-control pairs were enrolled. Median Apo A-I levels were lower in ischemic stroke cases versus controls (140 mg/dL versus 175 mg/dL, difference of 35 mg/dL, 95% CI -54 to -16) and in ischemic stroke versus ICH cases (140 mg/dL versus 180 mg/dL, difference of 40 mg/dL, 95% CI -57 to -23). Median paraoxonase-1 was lower in ischemic stroke cases than in both ICH cases and matched controls. Median Apo C-I was slightly lower in ischemic stroke cases than in ICH cases. There were no differences between groups for MMP-3, MMP-9, and Apo C-III. Conclusion Apo A-I and paraoxonase-1 levels may be clinically useful for ischemic stroke diagnosis and for differentiating between ischemic and hemorrhagic strokes.