CD84 Links T Cell and Platelet Activity in Cerebral Thrombo-Inflammation in Acute Stroke.

RATIONALE: Ischemic stroke is a leading cause of morbidity and mortality worldwide. Recanalization of the occluded vessel is essential but not sufficient to guarantee brain salvage. Experimental and clinical data suggest that infarcts often develop further due to a thromboinflammatory process critically involving platelets and T cells, but the underlying mechanisms are unknown. OBJECTIVE: We aimed to determine the role of CD (cluster of differentiation)-84 in acute ischemic stroke after recanalization and to dissect the underlying molecular thromboinflammatory mechanisms. METHODS AND RESULTS: Here, we show that mice lacking CD84-a homophilic immunoreceptor of the SLAM (signaling lymphocyte activation molecule) family-on either platelets or T cells displayed reduced cerebral CD4+ T-cell infiltration and thrombotic activity following experimental stroke resulting in reduced neurological damage. In vitro, platelet-derived soluble CD84 enhanced motility of wild-type but not of Cd84-/- CD4+ T cells suggesting homophilic CD84 interactions to drive this process. Clinically, human arterial blood directly sampled from the ischemic cerebral circulation indicated local shedding of platelet CD84. Moreover, high platelet CD84 expression levels were associated with poor outcome in patients with stroke. CONCLUSIONS: These results establish CD84 as a critical pathogenic effector and thus a potential pharmacological target in ischemic stroke.

Feasibility of platelet marker analysis in ischemic stroke patients and their association with one-year outcome. A pilot project within a subsample of the Stroke Induced Cardiac Failure in Mice and Men (SICFAIL) cohort study.

Patients with ischemic stroke (IS) are at increased risk of mortality and recurrent cerebro- or cardiovascular events. Determining prognosis after IS remains challenging but blood-based biomarkers might provide additional prognostic information. As platelets are crucially involved in the pathophysiology of vascular diseases, platelet surface proteins (PSP) are promising candidates as prognostic markers in the hyperacute stage. In this pilot study, feasibility of PSP analysis by flow cytometry (HMGB1, CD84, CXCR4, CXCR7, CD62p with and without ADP-stimulation, CD41, CD61, CD40, GPVI) was investigated in 99 (median 66 years, 67.5% male) acute IS patients admitted to Stroke Unit within a substudy of the Stroke-Induced Cardiac FAILure in mice and men (SICFAIL) cohort study. Association between PSP expression and unfavorable one-year outcome (cerebro- or cardiovascular event, all-cause mortality and care dependency defined as Barthel Index <60) was explored. PSP measurements were feasible. Several process- (e.g. temperatures, processing times) and patient-related factors (e.g. prestroke ischemic events, surgery, blood pressure, antiplatelet therapy) were identified to be potentially associated with PSP expression. Elevated CD40 levels above study population's median were associated with unfavorable outcome. Standardized conditions during blood draw and processing within the hyperacute stroke unit setting are required and patient-related characteristics must be considered for valid measurements of PSP.Trial registration: German Clinical Trials Register (DRKS00011615).

Should IV Thrombolysis be given in Patients with Suspected Ischemic Stroke but Unknown Symptom Onset and Without Diffusion-Weighted Imaging Lesion? - Results of a Case-Control Study.

BACKGROUND: Many acute ischemic stroke (AIS) patients present with unknown time of symptom onset (UTO). In these situations, wake-up MRI protocols can guide treatment decisions: patients with DWI (diffusion-weighted imaging) but no fluid-attenuated inversion recovery lesion were shown to benefit from IVT (intravenous thrombolysis). However, initial MRI of some stroke patients is DWI negative, leaving it unclear whether this subgroup profits from IVT. Therefore, we aimed to compare the safety and efficacy of IVT in wake-up AIS patients with or without a DWI lesion in initial imaging. METHODS: We performed a case-control study. All AIS patients with UTO who underwent wake-up MRI and were treated with IVT at a German University Hospital from 2013 to 2017 were included. Patients without (DWI-) were compared to patients with DWI lesion (DWI+) regarding clinico-radiological characteristics, adverse events, and outcome at discharge. Likely stroke mimics were excluded. RESULTS: Eleven DWI- and 32 DWI+ patients were included. There were no statistically significant differences regarding functional scores, age, sex, door-to-needle time, bleeding complications, and death. DWI+ patients more frequently had anterior circulation stroke (P = .049) and higher modified Rankin Scale (mRS) scores at discharge (P = .048). Solely in the DWI+ group 3 bleeding complications (2 asymptomatic hemorrhagic transformations, 1 muscle hematoma) and 3 deaths occurred (P = .29). A favourable outcome (mRS≤ 2) was achieved in 82% of the DWI- and in 58% of the DWI+ group (p > .05). CONCLUSIONS: Our data suggest that IVT may be used in DWI- patients with UTO with acute neurological symptoms very likely to be related to AIS.