Association of calprotectin with other inflammatory parameters in the prediction of mortality for ischemic stroke.

BACKGROUND: Inflammatory response plays an important role in many processes related to acute ischemic stroke (AIS). Calprotectin (S100A8/S100A9), released by monocytes and neutrophils, is a key protein in the regulation of inflammation and thrombosis. The purpose of this study is to evaluate the association of circulating calprotectin with other inflammatory biomarkers and AIS prognosis, as well as the calprotectin content in stroke thrombi. METHODS: Among the 748 patients treated at a comprehensive stroke center between 2015 and 2017, 413 patients with confirmed acute ischemic injury were prospectively evaluated. Patients with systemic inflammation or infection at onset were excluded. Plasma calprotectin was measured by ELISA in blood samples of AIS patients within the first 24 h. Univariate and multivariate logistic regression models were performed to evaluate its association with mortality and functional independence (FI) at 3 months (defined as modified Rankin Scale < 3) and hemorrhagic transformation (HT) after ischemic stroke. Further, S100A9 was localized by immunostaining in stroke thrombi (n = 44). RESULTS: Higher calprotectin levels were associated with 3-month mortality, HT, and lower 3-month FI. After adjusting for potential confounders, plasma calprotectin remained associated with 3-month mortality [OR (95% CI) 2.31 (1.13-4.73)]. Patients with calprotectin ≥ 2.26 µg/mL were 4 times more likely to die [OR 4.34 (1.95-9.67)]. Addition of calprotectin to clinical variables led to significant improvement in the discrimination capacity of the model [0.91 (0.87-0.95) vs 0.89 (0.85-0.93); p < 0.05]. A multimarker approach demonstrated that patients with increased calprotectin, CRP, and NLR had the poorest outcome with a mortality rate of 42.3% during follow-up. S100A9 protein, as part of the heterodimer calprotectin, was present in all thrombi retrieved from AIS patients. Mean S100A9 content was 3.5% and tended to be higher in patients who died (p = 0.09). Moreover, it positively correlated with platelets (Pearson r 0.46, p < 0.002), leukocytes (0.45, p < 0.01), and neutrophil elastase (0.70, p < 0.001) thrombus content. CONCLUSIONS: Plasma calprotectin is an independent predictor of 3-month mortality and provides complementary prognostic information to identify patients with poor outcome after AIS. The presence of S100A9 in stroke thrombi suggests a possible inflammatory mechanism in clot formation, and further studies are needed to determine its influence in resistance to reperfusion.

Mass Spectrometry-Based Proteomic Profiling of Thrombotic Material Obtained by Endovascular Thrombectomy in Patients with Ischemic Stroke.

Thrombotic material retrieved from acute ischemic stroke (AIS) patients represents a valuable source of biological information. In this study, we have developed a clinical proteomics workflow to characterize the protein cargo of thrombi derived from AIS patients. To analyze the thrombus proteome in a large-scale format, we developed a workflow that combines the isolation of thrombus by endovascular thrombectomy and peptide chromatographic fractionation coupled to mass-spectrometry. Using this workflow, we have characterized a specific proteomic expression profile derived from four AIS patients included in this study. Around 1600 protein species were unambiguously identified in the analyzed material. Functional bioinformatics analyses were performed, emphasizing a clustering of proteins with immunological functions as well as cardiopathy-related proteins with blood-cell dependent functions and peripheral vascular processes. In addition, we established a reference proteomic fingerprint of 341 proteins commonly detected in all patients. Protein interactome network of this subproteome revealed protein clusters involved in the interaction of fibronectin with 14-3-3 proteins, TGFß signaling, and TCP complex network. Taken together, our data contributes to the repertoire of the human thrombus proteome, serving as a reference library to increase our knowledge about the molecular basis of thrombus derived from AIS patients, paving the way toward the establishment of a quantitative approach necessary to detect and characterize potential novel biomarkers in the stroke field.

Circular RNA expression profile in blood according to ischemic stroke etiology.

BACKGROUND: The discovery of novel biomarkers of stroke etiology would be most helpful in management of acute ischemic stroke patients. Recently, circular RNAs (circRNAs) have been proposed as candidate biomarkers of neurological conditions due to its high stability. circRNAs function as sponges, sequestering miRNAs and are involved in most relevant biological functions. Our aim was to identify differentially expressed circRNAs in acute ischemic stroke patients according to stroke etiology. METHODS: A comprehensive expression profile of blood circRNAs was conducted by Arraystar Human circRNA arrays (13,617 probes) on a discovery cohort of 30 stroke patients with different stroke etiologies by TOAST classification. Real-time quantitative PCR (RT-qPCR) was used to validate array results in a cohort of 50 stroke patients. Functional in silico analysis was performed to identify potential interactions with microRNAs (miRNAs) and pathways underlying deregulated circRNAs. RESULTS: A set of 60 circRNAs were found to be upregulated in atherotrombotic versus cardioembolic strokes (fold-change > = 1.5 and p-value ≤ 0.05). Differential expression of hsa_circRNA_102488, originated from UBA52 gene, was replicated in the validation cohort. RNA-binding proteins (RBPs) sites of hsa_circRNA_102488 clustered around AGO2 and FUS proteins. Further functional analysis revealed interactions between deregulated circRNAs and a set of miRNAs involved in stroke-related pathways, such as fatty acid biogenesis or lysine degradation. CONCLUSION: Different stroke subtypes show specific profiles of circRNAs expression. circRNAs may serve as a new source of biomarkers of stroke etiology in acute ischemic stroke patients.

The growth factor response in ischemic rat retina and superior colliculus after brimonidine pre-treatment.

The alpha-2-adrenergic receptor agonist brimonidine has been shown to increase survival of retinal ganglion cells following ischemic injury to the rat retina. Increased expression of growth factors has been suggested to be involved in this action. We investigated expressional changes of growth factors and their receptors following transient retinal ischemia induced by selective ligature of ophthalmic vessels in rats pre-treated with vehicle or 0.5% brimonidine. In addition, analysis of expression in retinal samples following unilateral administration of brimonidine to normal tissue was performed. Tissue samples of retina and superior colliculus were collected at time points between 6h and 14 days of retinal reperfusion. Analysis of mRNA levels of the ligands BDNF, NT3, CNTF, FGF1, FGF2, FGF9 and HGF; as well as the receptors TrkB, TrkC, p75(NTR), CNTFRalpha, FGFR1, FGFR3, FGFR4 and HGFR were performed using qRT-PCR. The cell specific markers Thy1 and GFAP were analysed. We report transiently increased retinal levels of BDNF, NT3, p75(NTR), FGFR1 and HGFR and decreased levels of FGF9, HGF, TrkB, TrkC, FGFR4 and Thy1 following ischemia. The decreases were counteracted by brimonidine. Brimonidine treatment gave an increase in BDNF, NT3 and CNTF levels compared to the vehicle treated group. In superior colliculus increased levels of growth factor mRNA were found. In conclusion, transient ischemia has a profound effect on gene expression in rat retina. Alterations can also be seen in the superior colliculus but are smaller. Brimonidine pre-treatment attenuates an acute injury-induced response by decreasing the expression of several genes, among them p75(NTR). Brimonidine also causes a prolonged increase of several growth factors as well as receptors in retina and superior colliculus compared to the ischemic situation. The increased expression of several growth factors represents a coordinated growth factor system response that differs from the ischemia-induced changes and is likely part of the neuroprotective activity that is elicited by BMD pre-treatment.