Written by Charlotte Harrison, Science Writer
Ischemic stroke is notoriously difficult to treat, largely because of the narrow time window in which therapies are effective. Therefore, biomarkers are needed to improve patient diagnosis and care. A study in BMC Medicine is one of the first to analyse transcriptional profiles in immune cells and whole blood from stroke patients at distinct time points. The study results are a key step towards developing diagnostic biomarkers as well as time-specific therapies.
The researchers, from University of California at Davis, analysed the transcriptomic profiles of monocytes and neutrophils — which are known to mediate the immune response to stroke — as well as profiles of whole blood. Of note, the analysis was performed in patient samples from 0–24 h, 24–48 h, and >48 h after stroke, and the stroke aetiology was known.
Several analytical methods including differential gene expression, self-organizing maps and weighted gene co-expression network analysis enabled the authors to identify changes in gene expression after stroke.
Their results showed that monocytes, neutrophils and whole blood had distinct patterns of temporal gene expression and gene pathway changes. In particular, specific cytokines were enriched at different time points and for different stroke causes.
In general, gene expression was upregulated in neutrophils and downregulated in monocytes at each time point in cardioembolic, large-vessel and small-vessel strokes.
The researchers identified gene clusters with similar gene expression trajectories over time for different stroke aetiologies. These clusters might be useful for identifying biomarkers of stroke cause or type.
They also identified modules of co‐expressed genes that varied with time after stroke. Since these modules included hub genes of immunoglobulin genes in whole blood, this information might be useful for identifying biomarkers of stroke severity and outcome.
As well as improving our understanding of immune-system changes after stroke, the authors note that their results “point to the complexities of identifying biomarkers and treatment targets for stroke.”