Different expression patterns of inflammation-related genes and serum microRNAs in young-onset ischemic stroke

Abstract

Brain ischemia results in the activation of a cascade of inflammatory responses, contributing to the pathogenesis of stroke. This study aimed to assess the patterns of possible changes in the expression of specific inflammation-associated protein-encoding genes and miRNAs in the peripheral blood between the acute and chronic phase of young-onset cryptogenic (Cryp) and large-artery atherosclerotic (LAA) stroke. Blood and serum were collected from patients with cryptogenic and large-artery atherosclerotic stroke at the stroke onset and 1-year follow-up. The relative expression of inflammation-related genes was analysed at the mRNA and miRNA levels using real-time quantitative PCR. Moreover, the relationship between the relative gene expression levels and clinical data was assessed using several different statistical approaches. Seventy-three patients were included in this study, with a median age of 47 (IQR, 9) years. Approximately 72% were men. In patients with cryptogenic stroke, at the mRNA level, ICAM1, CXCL8, TNF, NFKBIA, PYCARD, IL1B, and IL18 were observed to be upregulated at the stroke onset compared to the 1-year follow-up. In patients with LAA stroke, only the expression of NFKBIA was significantly higher during acute stroke. Further, the miRNA serum levels of miR-21, miR-122, and miR-155 were higher at the onset of stroke in patients with cryptogenic stroke but not in those with LAA stroke. The differences between the relative gene expression levels during acute stroke and at the 1-year follow-up were more pronounced in patients with cryptogenic stroke with no cardiovascular risk factors. The expression changes of inflammatory genes in whole blood and miRNAs in the serum differ in patients with cryptogenic and LAA stroke.

Fig. 1

Multiple inflammation-associated genes were upregulated during cryptogenic (Cryp) stroke but not during large-artery atherosclerotic (LAA) stroke. The relative mRNA expression of the selected genes associated with the NF-κB (A,C) and inflammasome (B,D) pathways was measured using RT-qPCR from whole blood of patients with cryptogenic (Cryp) or LAA stroke immediately after the stroke onset (Cryp 1, LAA 1) or 1 year later (Cryp 2, LAA 2). Paired two-tailed t-test, *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001.

Fig. 2

Relative serum levels of selected inflammation-associated miRNAs. The relative expression of miRNAs was assessed from the total RNA purified from the serum of patients with cryptogenic (Cryp) (A) and LAA (B) stroke immediately after the stroke onset (Cryp 1, LAA 1) and 1 year later (Cryp 2, LAA 2). Paired two-tailed t-test, **p<0.01; ***p<0.001; ****p<0.0001.