Increased IL-1β, IL-8, and IL-17 mRNA Expression in Blood Mononuclear Cells Observed in a Prospective Ischemic Stroke Study

Abstract

Background and Purpose—Ischemic brain injury secondary to arterial occlusion is characterized by acute local inflammation, which involves accumulation of polymorphonuclear neutrophils (PMN). Factors that influence the recruitment of PMN could represent new therapeutic targets in acute stroke. In this prospective study we evaluated numbers of peripheral blood mononuclear cells (PBMC) expressing mRNA for interleukin (IL)-1β, IL-8, and IL-17 and macrophage inflammatory protein-1α (MIP-1α) after ischemic stroke.Methods—Peripheral blood was obtained on days 1 to 3, 4 to 10, and 20 to 31 after onset of symptoms. In situ hybridization with radiolabeled synthetic oligonucleotide probes was adopted to measure cytokine mRNA expression in PBMC. Plasma and cerebrospinal fluid levels of IL-8 were measured by an enzyme-linked immunosorbent assay.Results—Most patients with ischemic stroke had clearly elevated numbers of IL-1β, IL-8, and IL-17 mRNA expressing PBMC 1 to 3 days after onset of symptoms compared with healthy individuals (P<0.0001 for all comparisons). At follow-up after 20 to 31 days, numbers of IL-8 mRNA expressing PBMC were lower than during the acute stage (P<0.001), but only IL-1β and IL-17 mRNA expression had returned to the level of the healthy individuals. Numbers of MIP-1α mRNA expressing PBMC did not differ between patients with ischemic stroke and healthy individuals at any time point. A correlation was observed between numbers of IL-1β, IL-8, and IL-17 mRNA expressing PBMC and the degree of neurological impairment as measured by the Scandinavian Stroke Scale 1 to 3 days after onset of symptoms (r=0.5;P<0.01 for all correlations).Conclusions—A longitudinal study of patients with ischemic stroke revealed systemic increases of levels of IL-1β, IL-8, and IL-17 that correlated with Scandinavian Stroke Scale scores. IL-8 levels were further increased in cerebrospinal fluid.