Table 1.
Baseline characteristics of control and stroke groups at admission, including haematological parameters, vascular risk factors and admission details.
Fig 1.
Comparison of GPVI expression between control and stroke cohorts and GPVI-dimer as a function of total GPVI in control and stroke cohorts.
A) Total GPVI and B) GPVI-dimer are both significantly higher in the stroke population at admission compared to the control cohort (P <0.0001). P-values were calculated using an unpaired t-test and the error bars represent the mean MFI of each of the cohorts ± SD. C) Correlation between platelet surface total GPVI-dimer and GPVI-dimer. These data were calculated using Pearson correlation coefficient and the regression line is presented for each set of data. The control platelets show a narrow range of GPVI-dimer levels, which is negatively correlated to total GPVI (P <0.0001). In contrast, the surface GPVI-dimer of stroke patients’ platelets demonstrate strong positive correlation to the amount of total GPVI (P <0.0001) and in general have higher GPVI-dimer levels than the controls. MFI = mean fluorescence intensity.
Fig 2.
Comparison of P-selectin exposure between control and stroke cohorts and correlation between GPVI-dimer and P-selectin exposure.
A) Comparison of P-selectin surface exposure of the stroke patients with the controls show that the stroke patients have more activated “resting” platelets (i.e., before stimulation by exogenous agonist) and after CRP-XL (4 μg/mL) addition compared to the control group (P<0.0001). P-selectin exposure in response to ADP (0.5 μM) was not significantly different compared to controls. The error bars represent the median (Q1–Q3) %PP of each of the cohorts and P-values were calculated by the Mann-Whitney U-test for non-parametric data. B) GPVI-dimer expression and resting P-selectin exposure in both control and stroke patients are strongly correlated at admission (P <0.0001 for both). C) GPVI-dimer expression is correlated with P-selectin exposure in response to CRP-XL in the stroke patients at admission (P = 0.004). Correlations were calculated using Spearman’s rank correlation coefficient and regression line is presented for each data set. %PP = percentage of platelets positive, ns = not significant.
Fig 3.
Comparison of GPVI expression and P-selectin exposure in stroke patients at day-0 and at day-90 (n = 51).
A) Total GPVI expression is not different at day-90 compared to day-0 (P = 0.52). B) GPVI-dimer is significantly higher at day-90 compared to day-0 (P <0.0001). The error bars represent the mean MFI of each of the cohorts ± SD and P-values were calculated by a paired t-test. C) Resting P-selectin exposure (P <0.0001), P-selectin exposure induced by 0.5 μM ADP (P <0.0001), and P-selectin exposure induced by 4 μg/mL CRP-XL (P = 0.001) are all significantly lower at day-90. The error bars represent the median (Q1–Q3) %PP of each of the cohorts and P-values were calculated by the Wilcoxon signed-rank test for non-parametric data. ns = not significant. D) Comparison of P-selectin expressed on the platelet surface of stroke patients at day-0 and at day-90 after stroke and P-selectin of resting normal platelets. The P-selectin exposure on stroke patients at day-0 are strongly correlated to GPVI-dimer expression (P <0.0001) and higher than those of resting control platelets. By day-90, the stroke patients’ P-selectin exposure, albeit still correlated with GPVI-dimer level (P <0.0001), has decreased. Correlations were calculated using Spearman’s rank correlation coefficient and regression line is presented for each data set. MFI = mean fluorescent intensity, %PP = percentage of platelets positive.
Fig 4.
GPVI expression between control and stroke subtypes.
A) Total GPVI expression (P <0.0001) and B) GPVI-dimer expression are higher in all ischemic stroke etiologies as well as hemorrhagic strokes (P <0.0001). P-values were calculated using one-way ANOVA with Dunnett’s multiple comparisons testing and the error bars represent the mean MFI of each of the cohorts ± SD. C) Resting P-selectin expression is higher in ischemic and hemorrhagic stroke (P <0.0001). P-values were calculated by a Kruskal-Wallis test with Dunn’s multiple comparisons testing for non-parametric data and the error bars represent the median (Q1–Q3) %PP of each of the cohorts. Numbers in parentheses show the number of participants within each group. MFI = mean fluorescent intensity, %PP = percentage of platelets positive.
Table 2.
Simple linear regression to identify associations between total GPVI or GPVI-dimer expression and a single predictor variable in the stroke population.