Thrombo-inflammation in acute ischaemic stroke - implications for treatment.

Ischaemic stroke elicits a strong neuroinflammatory response, but the functional relevance and therapeutic potential of neuroinflammation has only recently become apparent. In acute experimental stroke, T cells contribute to ischaemia-reperfusion injury after recanalization in an antigen-independent manner. Surprisingly, the detrimental T cell effects are platelet-dependent. Glycoprotein (GP)Ib-mediated and GPVI-mediated platelet activation, but not GPIIb-IIIa-mediated platelet aggregation, is an important checkpoint that orchestrates thrombotic and pro-inflammatory pathways, and downstream activation of coagulation factor XII is a driving force of ischaemia-reperfusion injury in acute stroke. The evidence therefore suggests that T cells interact with platelets and facilitate further infarct development through a complex process that we refer to as thrombo-inflammation. Results of clinical trials of agents that target lymphocytes support this concept. However, in the majority of patients with ischaemic stroke, recanalization cannot be achieved and the contribution of T cells in the setting of the resultant permanent ischaemia and subacute stroke is less clear and more complex. In some settings, T cells still seem to aggravate neuronal damage late after the ischaemic insult, but stroke triggers systemic immunodepression, therefore further anti-inflammatory treatments would need to be used carefully in this context. Targeting stroke-related neuroinflammation could become an effective adjunct therapy to improve outcomes after ischaemic stroke, but this approach will require caution regarding the timing and avoidance of adverse effects.