Reduced Serum Level of Interleukin-10 is Associated with Cerebral Infarction: A Case-Control and Meta-Analysis Study

IL-10 expression limits inflammation and restricts the size of CNS damage from stroke. In this study, we examined the correlation between cerebral infarction (CI) and serum levels of interleukin-10 (IL-10) using a combination of case-control study and meta-analysis of published data, with an aim of understanding the relevance of serum IL-10 levels to CI development. This study enrolled a total of 169 CI patients admitted to the Second Hospital of Hebei Medical University between May 2011 and November 2014. During the same period, a group of 145 individuals were recruited at the same hospital as healthy controls after thorough physical examination. Serum IL-10 levels were measured by enzyme-linked immunosorbent assay (ELISA). SPSS 19.0 (IBM, 2010, Chicago, IL, USA) and Comprehensive Meta-Analysis 2.0 (CMA 2.0) software were used for data analysis. Serum levels of IL-10 (pg/mL) were significantly lower in CI patients when compared to healthy controls (15.36 ± 3.21 vs. 21.64 ± 5.17, t = 13.12, P < 0.001). In addition, patients with large artery atherosclerosis (LAAS), cardioembolic infarct (CEI), and lacunar infarct (LAC) displayed drastically reduced serum levels of IL-10 (pg/mL) compared to healthy controls (LAAS 14.77 ± 5.21, CEI 15.25 ± 5.10, LAC 16.58 ± 4.92, all P < 0.001). Interestingly, no significant differences were observed in the serum IL-10 levels when pair-wise comparisons were made between these three clinical subtypes of CI (all P > 0.05). Logistic regression analysis indicated that, with the exception of triglyceride (TG) and uric acid (UA) levels (both P > 0.05), the other seven parameters, including fasting blood glucose (FPG), total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), creatinine (Cr), systolic blood pressure (SBP), and diastolic blood pressure (DBP), strongly correlated with CI development (all P < 0.05). Meta-analysis of pooled data from nine case-control studies revealed an inverse correlation between the serum IL-10 levels and CI (SMD = 1.797, 95% CI 0.785~2.810, P = 0.001). Subgroup analysis based on country showed that low serum levels of IL-10 may be the major risk factor for CI in Croatia (SMD = 2.961, 95% CI 2.480~3.443, P < 0.001) and India (SMD = 1.440, 95% CI 1.129-1.750, P < 0.001). Further, subgroup analysis based on ethnicity showed that IL-10 serum levels and CI displayed negative relationship in Asians (SMD = 2.522, 95% CI 0.468~4.576, P = 0.016) but not in Caucasians (P > 0.05). Our study provided convincing evidence that the patients with CI exhibit consistently reduced serum levels of IL-10, and IL-10 may be a major player in the development and progression of CI.