TNF-a(-238G/A and -308G/A) gene polymorphisms may not contribute to the risk of ischemic stroke

Astrocyte-Derived TNF-α-Activated Platelets Promote Cerebral Ischemia/Reperfusion Injury by Regulating the RIP1/RIP3/AKT Signaling Pathway

Ischemic stroke is a clinical syndrome caused by the disruption of blood flow into cerebral tissues and is associated with high disability and mortality rates. Studies have established the pathological role of platelets in cerebral ischemia/reperfusion (I/R) injury, although the underlying mechanism of action remains largely unclear. In this study, we created an I/R mouse model via middle cerebral artery occlusion and reperfusion (MCAO/R) and analyzed the transcriptomic profiles of the ipsilateral and contralateral cortices using RNA-seq. We found that cerebral I/R injury induced platelet invasion and accumulation in the cerebral cortex by stimulating TNF-α secretion from activated astrocytes in the ischemic region, while TNF-α expression enhanced platelet reactivity through the RIP1/RIP3/AKT pathway. Furthermore, the inoculation of TNF-α-stimulated platelets aggravated I/R injury in mice, whereas the administration of anti-TNF-α antibodies at the onset of reperfusion alleviated ischemic damage. The RNA-seq results further showed that AP-1 transcriptionally activated TNF-α in the I/R-injured cortex by directly binding to the promoter region. These findings provide novel insights into the pathological role of platelets activated by reactive astrocyte-derived TNF-α in cerebral I/R injury.

TNF-α (G-308A) Polymorphism, Circulating Levels of TNF-α and IGF-1: Risk Factors for Ischemic Stroke—An Updated Meta-Analysis

Objective

Accumulated studies have explored gene polymorphisms and circulating levels of tumor necrosis factor (TNF)-α and insulin-like growth factor (IGF)-1 in the etiology of ischemic stroke (IS). Of the numerous etiopathological factors for IS, a single-nucleotide polymorphism (SNP) rs1800629 located in the TNF-α gene promoter region and increased levels of TNF-α were found to be associated with IS in different ethnic backgrounds. However, the published results are inconsistent and inconclusive. The primary objective of this meta-analysis was to investigate the concordance between rs1800629 polymorphism and IS. A secondary aim was to explore circulating levels of TNF-α and IGF-1 with IS in different ethnic backgrounds and different sourced specimens.

Methods

In this study, we examined whether rs1800629 genetic variant and levels of TNF-α and IGF-1 were related to the etiology of IS by performing a meta-analysis. Relevant case-control studies were retrieved by database searching and systematically selected according to established inclusion criteria.

Results

A total of 47 articles were identified that explored the relationship between the rs1800629 polymorphism and levels of TNF-α and IGF-1 with IS risk susceptibility. Statistical analyses revealed a significant association between the rs1800629 polymorphism and levels of TNF-α and IGF-1 with IS pathogenesis.

Conclusion

Our findings demonstrated that the TNF-α rs1800629 polymorphism, the increased levels of TNF-α, and decreased levels of IGF-1 were involved in the etiology of IS.

Promoter polymorphism of TNF-α (rs1800629) is associated with ischemic stroke susceptibility in a southern Thai population

Stroke represents the leading cause of disability and mortality amongst the elderly worldwide. Multiple risk factors, including both genetic and non-genetic components, as well as their interactions, are proposed as etiological factors involved in the development of ischemic stroke (IS). Promoter polymorphisms of the IL-6-174G/C (rs1800795) and TNF-α-308G/A (rs1800629) genes have been considered as predictive risk factors of IS; however, these have not yet been evaluated in a Thai population. The aims of this study were to investigate the association of IL-6-174G/C and TNF-α-308G/A polymorphisms with IS. Genomic DNA from 200 patients with IS and 200 controls were genotyped for IL-6-174G/C and TNF-α-308G/A polymorphisms using TaqMan™ SNP genotyping and quantitative PCR-high resolution melting analysis, respectively. It was found that the TNF-α-308 A allele was significantly associated with an increased risk of IS development compared with the G allele [odds ratio (OR)=2.044; 95% CI=1.154-3.620; P=0.014]. Moreover, the IS risk was significantly higher in the presence of TNF-α-308 GA or AA genotypes compared with that in the presence of GG genotypes with a dominant inheritance (OR=1.971; 95% CI=1.080-3.599; P=0.027). However, there was no association between IL-6-174G/C and the risk of IS development. The interaction study demonstrated that IL-6-174 GG and TNF-α-308 GG genotypes enhanced IS susceptibility when combined with hypertension, hyperlipidemia and alcohol consumption. Hypertensive and hyperlipidemic subjects with the TNF-α-308 GA and AA genotypes were more likely to develop IS compared with those who did not have these two conditions and had the GG genotype. In a matched study design (1:1), the IL-6-174 GC genotype was associated with higher IL-6 levels in the control group. Collectively, the present results highlight the utility of the TNF-α-308G/A polymorphism as a predictive genetic risk factor for development of IS.

Neurovascular Unit as a Source of Ischemic Stroke Biomarkers-Limitations of Experimental Studies and Perspectives for Clinical Application

Cerebral stroke, which is one of the most frequent causes of mortality and leading cause of disability in developed countries, often leads to devastating and irreversible brain damage. Neurological and neuroradiological diagnosis of stroke, especially in its acute phase, is frequently uncertain or inconclusive. This results in difficulties in identification of patients with poor prognosis or being at high risk for complications. It also makes difficult identification of these stroke patients who could benefit from more aggressive therapies. In contrary to the cardiovascular disease, no single biomarker is available for the ischemic stroke, addressing the abovementioned issues. This justifies the need for identifying of effective diagnostic measures characterized by high specificity and sensitivity. One of the promising avenues in this area is studies on the panels of biomarkers characteristic for processes which occur in different types and phases of ischemic stroke and represent all morphological constituents of the brains' neurovascular unit (NVU). In this review, we present the current state of knowledge concerning already-used or potentially applicable biomarkers of the ischemic stroke. We also discuss the perspectives for identification of biomarkers representative for different types and phases of the ischemic stroke, as well as for different constituents of NVU, which concentration levels correlate with extent of brain damage and patients' neurological status. Finally, a critical analysis of perspectives on further improvement of the ischemic stroke diagnosis is presented.

A Biosensor-Based Quantitative Analysis System of Major Active Ingredients in Lonicera japonica Thunb. Using UPLC-QDa and Chemometric Analysis

In the study, a surface plasmon resonance-based (SPR-based) competitive assay was performed to analyze different compounds’ inhibitory activity to TNF-α, an important pro-inflammatory cytokine in the pathogenesis of chronic inflammatory diseases. Moreover, the single mass spectrometry (MS) detection method was coupled with an ultra-high-performance liquid chromatography (UPLC) system for the routine quality control (QC) of a traditional Chinese medicine (TCM). The above quality control strategy was evaluated with Lonicera japonica Thunb. Analytes were firstly separated on a Waters ACQUITYTM UPLC HSS T3 column (2.1 × 50 mm; particle size = 1.8 μm) using a 0.1% formic acid gradient elution, then detected by negative ESI mass spectrometry. The limits of quantification (LOQ) for analytes reached 0.005–0.56 μg/mL. The LOD of the QDa detector was lower than that of the PDA detector, indicating its wider detection range. The QDa detector was also more suitable for the analysis of the complex matrix of TCM. The method showed excellent linearity, with regression coefficients higher than 0.9991. The average recoveries of the investigated analytes were in the range of 98.78–105.13%, with an RSD below 3.91%. The inter-day precision range (n = 3 days) was 2.51–4.54%. Compared to other detectors, this strategy could be widely applied in the quantitative analysis of TCM. In addition, the chemically latent data could be revealed using chemometric analysis. Importantly, this study provides an efficient screening method for small-molecule inhibitors targeting the TNF-α pathway.

Association between TNF-a promoter -308G/A polymorphism and essential hypertension in the Asian population: A meta-analysis

OBJECTIVE

The results of studies on the association between tumor necrosis factor-a -308G/A (TNF-a -308G/A) polymorphism, and susceptibility to essential hypertension are controversial. To derive a more precise estimation, we conducted a meta-analysis of all similar articles.

METHODS

The summary effect odds ratios and 95% confidence intervals were obtained. Funnel plots and Egger's test were used to estimate publication bias, and heterogeneity was assessed by the chi-square-based Q-test and I² test.

RESULTS

Nine studies (with 1437 cases and 1487 controls) were included. In the overall analysis, the combined results showed that there were significant differences in genotype distribution between essential hypertension cases and controls, AA+GA versus GG (OR = 1.53, 95% CI: 1.25-1.88, p < 0.00001). In the stratified analysis by country, we found that essential hypertension cases had a significantly higher frequency of AA+GA versus GG (OR = 1.47, 95% CI: 1.18-1.81, p = 0.0004) than control in the Asian population.

CONCLUSIONS

This meta-analysis supports previous findings that TNF-a -308G/A polymorphism may increase the risk of essential hypertension, at least in the Asian population.

Treadmill exercise promotes neuroprotection against cerebral ischemia-reperfusion injury via downregulation of pro-inflammatory mediators

BACKGROUND

Stroke is one of the major causes of morbidity and mortality worldwide, which is associated with serious physical deficits that affect daily living and quality of life and produces immense public health and economic burdens. Both clinical and experimental data suggest that early physical training after ischemic brain injury may reduce the extent of motor dysfunction. However, the exact mechanisms have not been fully elucidated. The aim of this study was to investigate the effects of aerobic exercise on neuroprotection and understand the underlying mechanisms.

MATERIALS AND METHODS

Middle cerebral artery occlusion (MCAO) was conducted to establish a rat model of cerebral ischemia-reperfusion injury to mimic ischemic stroke. Experimental animals were divided into the following three groups: sham (n=34), MCAO (n=39), and MCAO plus treadmill exercise (n=28). The effects of aerobic exercise intervention on ischemic brain injury were evaluated using functional scoring, histological analysis, and Bio-Plex Protein Assays.

RESULTS

Early aerobic exercise intervention was found to improve motor function, prevent death of neuronal cells, and suppress the activation of microglial cells and astrocytes. Furthermore, it was observed that aerobic exercise downregulated the expression of the cytokine interleukin-1β and the chemokine monocyte chemotactic protein-1 after transient MCAO in experimental rats.

CONCLUSION

This study demonstrates that treadmill exercise rehabilitation promotes neuroprotection against cerebral ischemia-reperfusion injury via the downregulation of proinflammatory mediators.