Highlighting the Role of Universally Available and Innate Immune Cell Counts in Acute Ischemic Stroke: A Scoping Review

Abstract

Stroke is one of the leading causes of adult disability and the second leading cause of death worldwide. The immune system actively participates in the pathobiological process of acute ischemic stroke (AIS), during the index event and the repair process. Research on neurovascular inflammation has created a renewed interest in the use of easily available biomarkers reflective of innate and adaptive immunological changes with potential diagnostic, prognostic, and therapeutic implications particularly in AIS. The current scoping review aimed to assess the significance the neutrophil to lymphocyte (NLR) in AIS and its related complications and explore their association with post-stroke recovery trajectory. The Arksey and O’Malley methodological framework was employed to review the published papers on the neutrophil–lymphocyte ratio (NLR) and AIS in late November 2020. Only studies published in English from 2000–2020 were included in this scoping review. Fifty-three published papers were reviewed. This review’s key finding is that a canonical inflammatory response occurs in the hyperacute, acute, subacute, and chronic stages of stroke. An excessive circulating innate immune cells (neutrophils) and reduced circulating adaptive immune cells (lymphocytes) are associated with poorer outcomes during the acute interventions as well as the recovery trajectory. This scoping review’s findings highlights the utility of a systems biology-based approach in stroke care.