Role of interleukin-7 in acute large vessel occlusion stroke.

Introduction: Emergent large vessel occlusion (ELVO) stroke is a severe ischemic subtype with high morbidity despite mechanical thrombectomy (MT). Current biomarkers inadequately capture the intracranial immune response driving stroke progression. Interleukin-7 (IL-7) is implicated in neuroinflammation but remains understudied in stroke. This study investigates intracranial and systemic IL-7 expression in patients with ELVO stroke, assessing its association with infarct burden and its potential as a prognostic biomarker.

Methods: Plasma samples were collected from patients with ELVO stroke during MT and from CVD control patients undergoing elective diagnostic cerebral angiography. Systemic and intracranial arterial blood was processed with a proximity extension assay (Olink Proteomics) to quantify IL-7 and other cytokines. Infarct and edema volumes were assessed using MRI or CT at 24 hours post-procedure. Spearman correlation and multivariable linear regression models adjusted for the National Institutes of Health Stroke Scale (NIHSS) score at admission were used to evaluate associations between IL-7 levels (intracranial, systemic, and the difference between compartments) and clinical outcomes.

Results: Intracranial IL-7 was independently associated with infarct volume (β=-42 052, P=0.0432; R²=0.232), demonstrating greater overall best fit than systemic IL-7 (P=0.8408) and systemic-intracranial differences (P=0.0857). Intracranial IL-7 was also correlated with infarct volume, edema, and NIHSS score at discharge.

Conclusion: Intracranial IL-7 is a significant predictor of infarct burden in ELVO stroke, highlighting its role in localized immune responses. Systemic IL-7 lacked predictive value, suggesting spatially restricted IL-7 signaling within the ischemic environment. IL-7 may serve as a biomarker for stroke severity and a potential therapeutic target.