Mateusz G. Adamski

A-G-4G haplotype of PAI-1 gene polymorphisms −844 G/A, HindIII G/C, and −675 4G/5G is associated with increased risk of ischemic stroke caused by small vessel disease

Background –  Plasminogen activator inhibitor type 1 (PAI‐1) is the major inhibitor of fibrinolysis. It was reported that PAI‐1 gene polymorphisms affected PAI‐1 level and might therefore influence the risk of vascular diseases, including stroke. We studied the association of three common polymorphisms in PAI‐1 gene (−844 G/A, −675 4G/5G, and HindIII G/C) with the odds of different causes of ischemic stroke.

A Method for Quantitative Analysis of Standard and High-Throughput qPCR Expression Data Based on Input Sample Quantity

Over the past decade rapid advances have occurred in the understanding of RNA expression and its regulation. Quantitative polymerase chain reactions (qPCR) have become the gold standard for quantifying gene expression. Microfluidic next generation, high throughput qPCR now permits the detection of transcript copy number in thousands of reactions simultaneously, dramatically increasing the sensitivity over standard qPCR. Here we present a gene expression analysis method applicable to both standard polymerase chain reactions (qPCR) and high throughput qPCR. This technique is adjusted to the input sample quantity (e.g., the number of cells) and is independent of control gene expression. It is efficiency-corrected and with the use of a universal reference sample (commercial complementary DNA (cDNA)) permits the normalization of results between different batches and between different instruments – regardless of potential differences in transcript amplification efficiency. Modifications of the input quantity method include (1) the achievement of absolute quantification and (2) a non-efficiency corrected analysis. When compared to other commonly used algorithms the input quantity method proved to be valid. This method is of particular value for clinical studies of whole blood and circulating leukocytes where cell counts are readily available.

Next-Generation qPCR for the High- Throughput Measurement of Gene Expression in Multiple Leukocyte Subsets

Clinical studies of gene expression are increasingly using the whole blood, peripheral blood mononuclear cells, and leukocyte subsets involved in the innate and adaptive immune responses. However, the small amount of RNA available in the clinical setting is a limitation for commonly used methods such as quantitative polymerase chain reactions (qPCR) and microarrays. Our aim was to design 96 gene assays to simultaneously measure gene expression in the whole blood and seven leukocyte subsets using a new-generation qPCR method—high-throughput nanofluidic reverse transcription qPCR (HT RT-qPCR). The leukocyte subset purity was 94% to 98% for seven subsets and was less for the γδ T-cell receptor subset (80%). The HT RT-qPCR replicate sample measurements were highly reproducible (r = 0.997, p < 2.2 × 10−16), and the ΔΔCt values from HT RT-qPCR correlated significantly with those from qPCR. The control genes were differentially expressed across the eight leukocyte subsets in the control subjects (p = 1.3 × 10−5, analysis of variance). Two analytical methods, absolute and relative, gave concordant results and were significantly correlated (p = 1.9 × 10−9). HT RT-qPCR permits the rapid, reproducible, and quantitative measurement of multiple transcripts using minimal sample amounts. The protocol described yielded leukocyte subsets of high purity and identified two analytic methods for use.

Pre-Existing Hypertension Dominates γδT Cell Reduction in Human Ischemic Stroke

T lymphocytes may play an important role in the evolution of ischemic stroke. Depletion of γδT cells has been found to abrogate ischemia reperfusion injury in murine stroke. However, the role of γδT cells in human ischemic stroke is unknown. We aimed to determine γδT cell counts and γδT cell interleukin 17A (IL-17A) production in the clinical setting of ischemic stroke. We also aimed to determine the associations of γδT cell counts with ischemic lesion volume, measures of clinical severity and with major stroke risk factors. Peripheral blood samples from 43 acute ischemic stroke patients and 26 control subjects matched on race and gender were used for flow cytometry and complete blood count analyses. Subsequently, cytokine levels and gene expression were measured in γδT cells. The number of circulating γδT cells was decreased by almost 50% (p = 0.005) in the stroke patients. γδT cell counts did not correlate with lesion volume on magnetic resonance diffusion-weighted imaging or with clinical severity in the stroke patients, but γδT cells showed elevated levels of IL-17A (p = 0.048). Decreased γδT cell counts were also associated with older age (p = 0.004), pre-existing hypertension (p = 0.0005) and prevalent coronary artery disease (p = 0.03), with pre-existing hypertension being the most significant predictor of γδT cell counts in a multivariable analysis. γδT cells in human ischemic stroke are reduced in number and show elevated levels of IL-17A. A major reduction in γδT lymphocytes also occurs in hypertension and may contribute to the development of hypertension-mediated stroke and vascular disease.

The AGTR1 gene A1166C polymorphism as a risk factor and outcome predictor of primary intracerebral and aneurysmal subarachnoid hemorrhages

Associations between the angiotensin II type 1 receptor (AGTR1) gene A1166C polymorphism and hypertension, aortic abdominal aneurysms (as a risk factor) as well as cardiovascular disorders (as a risk factor and an outcome predictor) have been demonstrated. We aimed to investigate the role of this polymorphism as risk factors and outcome predictors in primary intracerebral hemorrhage (PICH) and aneurysmal subarachnoid hemorrhage (aSAH). We have prospectively recruited 1078 Polish participants to the study: 261 PICH patients, 392 aSAH patients, and 425 unrelated control subjects. The A1166C AGTR1 gene polymorphism was studied using the tetra-primer ARMS-PCR method. Allele and genotype frequencies were compared with other ethnically different populations. The A1166C polymorphism was not associated with the risk of PICH or aSAH. Among the aSAH patients the AA genotype was associated with a good outcome, defined by a Glasgow Outcome Scale of 4 or 5 (p<0.02). The distribution of A1166C genotypes in our cohort did not differ from other white or other populations of European descent. In conclusion, we found an association between the A1166C AGTR1 polymorphism and outcome of aSAH patients, but not with the risk of PICH or aSAH.

Expression profile based gene clusters for ischemic stroke detection.

In microarray studies alterations in gene expression in circulating leukocytes have shown utility for ischemic stroke diagnosis. We studied forty candidate markers identified in three gene expression profiles to (1) quantitate individual transcript expression, (2) identify transcript clusters and (3) assess the clinical diagnostic utility of the clusters identified for ischemic stroke detection. Using high throughput next generation qPCR 16 of the 40 transcripts were significantly up-regulated in stroke patients relative to control subjects (p<0.05). Six clusters of between 5 and 7 transcripts were identified that discriminated between stroke and control (p values between 1.01e-9 and 0.03). A 7 transcript cluster containing PLBD1, PYGL, BST1, DUSP1, FOS, VCAN and FCGR1A showed high accuracy for stroke classification (AUC=0.854). These results validate and improve upon the diagnostic value of transcripts identified in microarray studies for ischemic stroke. The clusters identified show promise for acute ischemic stroke detection.

Splenic measurements in ischemic stroke: assessment of baseline size

Dear Editor, we read with interest the recent paper by Sahota et al. (1). Using ultrasound measurements, spleen volumes were assessed during the first sevento eight-days of ischemic stroke and compared with volumes obtained in healthy control subjects. In the first 72 h of stroke, splenic volumes were initially smaller than in the controls and then became progressively larger between days 4 and 8. This suggested that an initial splenic contraction in stroke was followed by expansion. This interpretation was confounded by the lack of spleen volume measurements prior to stroke. The authors proposed that measuring spleen size at 90 days could provide an indication of prestroke spleen size. In a pilot sample of six patients, we have found the spleen size to be fairly stable between the subacute (median fivedays) and chronic (90 days) phases of ischemic stroke, supporting Sahota’s et al.’s proposition and interpretation of their results. Using combined length (L) and width (W) data, the mean spleen size (L × W) five-days poststroke was 34·1 ± 18·9 cm compared with 32·3 ± 19·0 cm at 90 days (P = 0·9). Measuring splenic depth was challenging and appears to correlate moderately with spleen volume (2).

A1/A2 polymorphism of GpIIIa gene and a risk of aneurysmal subarachnoid haemorrhage.

Platelet glycoproteins are involved in pathophysiology of cerebrovascular diseases. The aim of this study was to investigate the association between the GpIIIa gene A1/A2 polymorphism and a risk of aneurysmal subarachnoid haemorrhage (SAH) in a Polish population. In a case-control study we genotyped 288 Caucasian patients with aneurysmal SAH and 457 age-, gender- and race-matched controls. The GpIIIa A1/A2 polymorphism was genotyped with RFLP technique. No difference was found in the distribution of the polymorphism between the cases and controls (cases: A1A1-201 (69.8%), A1A2-83 (28.8%) and A2A2-4 (1.4%) vs. controls: A1A1-323 (70.7%); A1A2-128 (28.0%); A2A2-6 (1.3%), P>0.05. In a multivariate analysis female gender (OR=1.950; 95%CI: 1.308-2.907), hypertension (OR=4.774; 95%CI: 3.048-7.478) and smoking (OR=2.034; 95%CI: 1.366-3.030), but not GpIIIa A1/A2 polymorphism, were independent risk factors for aneurysmal SAH. The GpIIIa A1/A2 polymorphism is not a risk factor of aneurysmal SAH in a Polish population.

Current and future bioanalytical approaches for stroke assessment

Efforts are underway to develop novel platforms for stroke diagnosis to meet the criteria for effective treatment within the narrow time window mandated by the FDA-approved therapeutic (<3 h). Blood-based biomarkers could be used for rapid stroke diagnosis and coupled with new analytical tools, could serve as an attractive platform for managing stroke-related diseases. In this review, we will discuss the physiological processes associated with stroke and current diagnostic tools as well as their associated shortcomings. We will then review information on blood-based biomarkers and various detection technologies. In particular, point of care testing that permits small blood volumes required for the analysis and rapid turn-around time measurements of multiple markers will be presented.

Recent and near-future advances in nucleic acid-based diagnosis of stroke

Stroke is a leading cause of death and disability in adults, but at present, treatment for ischemic stroke reaches only a small percentage of patients. This is because of the very short time window for treatment and the time-consuming evaluation involved. Intense efforts are underway to find novel approaches to expedite stroke diagnosis and treatment. In this review, we provide the rationale for the use of blood-based nucleic acid biomarkers to advance stroke diagnosis. We describe mRNA markers identified in genomic profiling of circulating leukocytes and then outline technological issues involved in the application of these results. We then describe the novel point-of-care technology that is in development for the rapid detection of multiple mRNA molecules in circulating leukocytes.