Low ficolin-3 levels in early follow-up serum samples are associated with the severity and unfavorable outcome of acute ischemic stroke

Abstract

Background: A number of data indicate that the lectin pathway of complement activation contributes to the pathophysiology of ischemic stroke. The lectin pathway may be triggered by the binding of mannose-binding lectin (MBL), ficolin-2 or ficolin-3 to different ligands. Although several papers demonstrated the significance of MBL in ischemic stroke, the role of ficolins has not been examined.

Methods: Sera were obtained within 12 hours after the onset of ischemic stroke (admission samples) and 3-4 days later (follow-up samples) from 65 patients. The control group comprised 100 healthy individuals and 135 patients with significant carotid stenosis (patient controls). The concentrations of ficolin-2 and ficolin-3, initiator molecules of the lectin complement pathway, were measured by ELISA methods. Concentration of C-reactive protein (CRP) was also determined by a particle-enhanced immunturbidimetric assay.

Results: Concentrations of both ficolin-2 and ficolin-3 were significantly (p < 0.001) decreased in both the admission and in the follow-up samples of patients with definite ischemic stroke as compared to healthy subjects. Concentrations of ficolin-2 and ficolin-3 were even higher in patient controls than in healthy subjects, indicating that the decreased levels in sera during the acute phase of stroke are related to the acute ischemic event. Ficolin-3 levels in the follow-up samples inversely correlated with the severity of stroke indicated by NIH scale on admission. In follow-up samples an inverse correlation was observed between ficolin-3 levels and concentration of S100β, an indicator of the size of cerebral infarct. Patients with low ficolin-3 levels and high CRP levels in the follow up samples had a significantly worse outcome (adjusted ORs 5.6 and 3.9, respectively) as measured by the modified Rankin scale compared to patients with higher ficolin-3 and lower CRP concentrations. High CRP concentrations were similarly predictive for worse outcome, and the effects of low ficolin-3 and high CRP were independent.

Conclusions: Our findings indicate that ficolin-mediated lectin pathways of complement activation contribute to the pathogenesis of ischemic stroke and may be additive to complement-independent inflammatory processes.

Figure 1

Concentrations of ficolin-2, ficolin-3 and C-reactive protein in the sera of patients with acute ischemic stroke. Concentrations at the time of hospital admission and on day 3, as compared to healthy controls (HC) and patient controls (PC, patients with > 70% stenosis of the carotid artery without acute stroke) are shown. P values (* < 0.05, *** < 0.01) for the non-parametric Kruskal-Wallis test followed by the Dunn post hoc test are indicated.

Figure 2

Correlation between ficolin-3 levels with severity and outcome of stroke and size of infarct. Panel A: Negative correlation between serum ficolin-3 levels in follow-up (FU) samples and the severity of stroke as assessed by the NIH stroke scale at admission in 65 patients with ischemic stroke. Patients with unfavorable (≥ 16) vs. favorable (< 16) NIH scale were compared. P value of Mann-Whitney test is indicated. Panel B: Negative correlation between serum ficolin-3 levels in follow-up samples and the size of cerebral infarct as assessed by the S100β level in follow-up samples. Spearman's correlation coefficient and its significance is indicated. Panel C: Positive correlation between serum CRP levels in follow-up samples and the severity of stroke as assessed by the NIH scale at admission in 65 patients with ischemic stroke. Patients with unfavorable (≥ 16) vs. favorable (< 16) NIH scale were compared. P value of Mann-Whitney test is indicated. Panel D: No significant correlation between serum CRP levels in follow-up samples and the size of cerebral infarct as assessed by the S100β level in follow-up samples. Spearman's correlation coefficient and its significance is indicated.

Figure 3

Relationship of serum ficolin-3 and CRP levels with outcome. Differences in ficolin 3 (left panels, A, C) and CRP (right panels, B, D) levels measured in admission samples (upper panels, A, B) and in follow-up samples (lower panel, C, D) comparing patients with a favorable (modified Rankin scale: 1 or 2) and an unfavorable (modified Rankin scale 3 to 6) outcome. In the case of the CRP calculations, nine patients with infectious complications were excluded from the analysis. The significance of the Mann-Whitney test is indicated.

Figure 4

Relationship between the baseline NIH score scale values and the 3-day serum S100β concentration with the outcome of the disease in 65 patients with ischemic stroke. Panel A: Distribution of the patients with different outcome of the disease among patients with low (< 6), medium (6-10) and high (> 10) baseline NIHSS scale. P value for χ² test is indicated. Panel B: Differences in the S100β concentration between patients with favorable (modified Rankin score: 0-2) and unfavorable modified Rankin score: 3-6) outcome.