Abstract DP217: Association of Interleukin-6 Levels with Poor Functional Outcomes and Reperfusion Injury After Endovascular Thrombectomy

Background: Even though endovascular thrombectomy (EVT) improves the outcomes in patients with acute ischemic stroke (AIS), half of patients still develop poor outcomes after successful reperfusion, in which reperfusion injury is one contributing mechanism. Cytokines play crucial roles in neuroinflammation of stroke, but their roles in reperfusion injury remain to be clarified. This study aimed to identify the cytokines associated with functional outcomes and reperfusion injury in stroke patients undergoing EVT. Methods: Patients with AIS who underwent EVT and non-stroke controls were prospectively enrolled between February 2019 and May 2023. Plasma samples were collected at pre-EVT (T1), immediately post-EVT (T2), and 24 h post-EVT (T3) for stroke patients, and once for controls. In Stage 1 (Cohort 1: 10 patients, 10 controls), 28 cytokines were screened by multiplex immunoassay to identify stroke- or reperfusion-related candidates, which were then quantified in Stage 2 (Cohort 2). Cytokine levels were log-transformed for analysis. Reperfusion injury was defined radiologically, and 3-month modified Rankin Scale (mRS) 3–6 indicated poor functional outcomes. Results: A total of 12 cytokines were analyzed in Cohort 2, comprising 150 patients and 50 controls. Stroke group had higher levels of interleukin-6 (IL-6), interleukin-9, interleukin-10, interleukin-15, granulocyte-macrophage colony-stimulating factor, and galactin-1, whereas lower levels of interleukin-12, tumor necrosis factor-α, and interleukin-33 compared to controls. Poor functional outcomes occurred in 57.5 % of these stroke patients. In multivariate logistic regression models by adjusting significant clinical variables, poor functional outcomes were associated with higher levels of IL-6 at T1 and T2 (adjusted odds ratio aOR 2.81 and 2.70, p = 0.028 and 0.037, respectively), interleukin-10 at T1 and T2 (aOR 4.43 and 3.62, p = 0.006 and 0.019, respectively), and interleukin-15 at T1 (aOR 2.87, p = 0.020). Additionally, reperfusion injury was present in 34.0 % of these stroke patients and was independently associated with higher IL-6 levels at all time points (aOR 2.80, 2.40, and 6.28, p = 0.005, 0.010, and 0.003, respectively at T1 to T3). Conclusions: This study showed that a high IL-6 level before or immediately after EVT was significantly associated with poor functional outcomes and reperfusion injury in patients with acute ischemic stroke.