Evaluation of Blood-Based Biomarkers for Clinical Discrimination of Asymptomatic Carotid Artery Stenosis Patients with Ulcerated Plaques.

Background: Although analysis of plaque composition using noninvasive imaging helps identify plaques prone to rupture, simultaneous assessment of factors involved in ulceration associated with plaque rupture, with imaging of carotid plaque characteristics, is essential to identify high-risk groups in asymptomatic carotid stenosis (ACS).

Aims: The current study aimed to investigate blood-based biomarkers for detecting plaque ulceration in asymptomatic carotid stenosis (ACS) patients by analyzing plaque material and surface morphology using RNA sequencing (RNA-Seq).

Materials and methods: After RNA isolation, RNA-Seq and analyzing were performed using the Ion AmpliSeq Transcriptome Human Gene Expression Panel and IPA. Expression levels were analyzed to validate IPA results using RT-qPCR and ELISA.

Results & discussion: Based on IPA results, the genes that can be used in this discrimination were determined to be involved in the pathways as follows: (i) actin skeletal system, (ii) integrin, and (iii) ABRA signaling. Then, the determined fold changes were validated in RT-qPCR. Based on results, CHI3L2, IL-6, and CCL24 gene expression levels were determined to be -2.91-, -1.3-, and -3.66- fold downregulated, and FHL5 gene expression levels were determined to be 1,61- fold upregulated (p<0.05). After validation in blood material, only the FHL5 expression level was determined to be upregulated in both plaque and blood materials.

Conclusion: This is the first study to report that blood FHL5 levels may help discriminate high-risk groups of asymptomatic carotid stenosis (ACS) patients with ulcerated plaques, based on plaque surface morphology and biological characteristics. Thus, this study provides the first evidence supporting the biomarker potential of FHL5 gene expression levels in the blood of ACS patients with ulcerated plaques.