Purinergic signaling: a potential therapeutic target for ischemic stroke

Design, Synthesis, and Biological Evaluation of 4-(Difluoromethyl)-1H-imidazole-5-carboxylic Acids/4-(3-Cyanophenoxy)pyrimidine-5-carboxylic Acids as P2Y1 Receptor Antagonists for Ischemic Stroke Treatment

To develop effective agents for ischemic stroke, compounds 19 (IC50 = 0.49 μM) and 36b (IC50 = 0.50 μM), as analogues of our previously reported antiplatelet agent HNW001, were identified as potent P2Y1 receptor antagonists, which were superior to HNW001 and BPTU (IC50 = 4.07 and 2.50 μM, respectively). Notably, these two compounds showed remarkable neuroprotective potency against oxidative stress by upregulating nuclear Nrf2 protein levels in vitro. Additionally, compounds 19 and 36b demonstrated favorable blood-brain barrier penetration potential in rats, and the rat MCAO model showed that they could effectively reduce infarction sizes with ED50 values of 8.39 and 4.60 mg/kg, respectively. Meanwhile, they could remarkably ameliorate neurobehavioral function, brain water content, oxidative parameters, and hippocampal tissue damage following MCAO. Thus, compounds 19 and 36b were promising lead compounds for developing effective agents to treat ischemic stroke.

Overexpressed CD73 attenuates GSDMD-mediated astrocyte pyroptosis induced by cerebral ischemia-reperfusion injury through the A2B/NF-κB pathway

Ischemic stroke, resulting from the blockage or narrowing of cerebral vessels, causes brain tissue damage due to ischemia and hypoxia. Although reperfusion therapy is essential to restore blood flow, it may also result in reperfusion injury, causing secondary damage through mechanisms like oxidative stress, inflammation, and excitotoxicity. These effects significantly impact astrocytes, neurons, and endothelial cells, aggravating brain injury and disrupting the blood-brain barrier. CD73, an ectoenzyme that regulates adenosine production through ATP hydrolysis, plays a critical role in purinergic signaling and neuroprotection. During ischemic stroke, CD73 expression is dynamically regulated in response to ischemia and inflammation. It catalyzes the conversion of AMP to adenosine, which activates adenosine receptors to exert neuroprotective effects. Targeting the CD73-adenosine pathway presents a potential therapeutic strategy for mitigating ischemic stroke damage. Pyroptosis, a highly inflammatory form of programmed cell death mediated by inflammasomes like NLRP3 and caspases, plays a significant role in cerebral ischemia-reperfusion injury. Astrocytes, the most abundant CNS cells, contribute to both neuroprotection and injury, with pyroptosis exacerbating inflammation and brain damage. Regulating astrocyte pyroptosis is a promising therapeutic target. Our study investigates CD73's role in regulating astrocyte pyroptosis during ischemia-reperfusion injury. Using CD73 knockout mice and overexpression models, along with in vitro oxygen-glucose deprivation/reperfusion experiments, we found that CD73 overexpression reduces GSDMD-mediated astrocyte pyroptosis via the A2B/NF-κB pathway. These findings offer a novel approach to reducing neuroinflammation, protecting astrocytes, and improving outcomes in ischemic stroke.

Endothelial cell Pannexin1 overexpression impairs ischemic stroke outcome in a sex-dependent manner

Ischemic stroke is a leading cause of morbidity and mortality. We have previously shown that deletion of endothelial cell (EC) Panx1 reduces ischemic stroke infarct volume and reduces cerebral arterial myogenic reactivity, which regulates cerebral blood flow. We hypothesized that EC Panx1 content dictates ischemic stroke outcome and thus increased EC Panx1 expression will worsen ischemic stroke outcomes due to exacerbated myogenic tone development and impaired cerebral blood flow recovery. To test this, we generated the Cdh5-CreERT2+ ROSA26-hPanx1Tg mouse model that conditionally overexpresses the human isoform of Panx1 specifically in EC. We have found that cerebral myogenic reactivity is significantly increased with overexpression of EC Panx1 only in female mice, without alterations in peripheral vascular reactivity or blood pressure regulation. Similarly, we found that infarct size was increased and recovery of cerebral blood flow was reduced in female but not male EC Panx1 overexpressing mice. Our findings indicate a role for EC Panx1 as a mediator of ischemic stroke recovery. Furthermore, these data suggest a potential sex-dependent effect for EC Panx1, where females are more sensitive to increased EC Panx1 in cerebral vascular function and may provide a potential therapeutic target for the treatment of ischemic stroke in women.

The Study of the Protection Mechanism of Calycosin-7-O-β-d-Glucoside Against Oxygen-Glucose Deprivation/Reperfusion in HT22 Cells Based on Non-Targeted Metabolomics and Network Analysis

The cell non-targeted metabolomics technique was used to investigate the potential mechanism of Caly-cosin-7-O-β-d-glucoside (CAG) against cell oxygen-glucose deprivation/reperfusion (OGD/R). The OGD/R-injured HT22 cell model was constructed. The cells were divided into control, OGD/R, Edaravone (EDA), CAG-L, CAG-M, and CAG-H groups. The protective effect of CAG on OGD/R-injured nerve cells and its potential mechanism was investigated by detecting ROS levels, apoptosis rate, glutamic acid (Glu), γ-aminobutyric acid (GABA), nitric oxide (NO), and combining with cell non-targeted metabolomics. The results showed that after OGD/R, ROS levels, apoptosis rate, Glu and NO concentrations were significantly increased, while the concentrations of GABA were decreased considerably, which improved in a dose-dependent manner after CAG intervention. Cell non-targeted metabolomics results showed that CAG can dramatically improve the metabolomic characteristics of OGD/R-injured HT22 cells. Through bioinformatics analysis and molecular docking, it was found that purine metabolism may be an important pathway for CAG to treat OGD/R injury, and key proteins screened may be important targets for improving OGD/R injury. Therefore, CAG may protect OGD/R-injured HT22 cells by inhibiting apoptosis and oxidative stress, improving energy supply and the metabolomic characteristics of OGD/R-injured HT22 cells by regulating purine metabolism.

Causal relationship between plasma metabolites and carpal tunnel syndrome risk: evidence from a mendelian randomization study

Background

Carpal tunnel syndrome (CTS) is a common symptom of nerve compression and a leading cause of pain and hand dysfunction. However, the underlying biological mechanisms are not fully understood. The aim of this study was to reveal the causal effect of circulating metabolites on susceptibility to CTS.

Methods

We employed various Mendelian randomization (MR) methods, including Inverse Variance Weighted, MR-Egger, Weighted Median, Simple Mode, and Weighted Model, to examine the association between 1,400 metabolites and the risk of developing CTS. We obtained Single-nucleotide polymorphisms (SNPs) associated with 1,400 metabolites from the Canadian Longitudinal Study on Aging (CLSA) cohort. CTS data was derived from the FinnGen consortium, which included 11,208 cases and 1,95,047 controls of European ancestry.

Results

The results of the two-sample MR study indicated an association between 77 metabolites (metabolite ratios) and CTS. After false discovery rate (FDR) correction, a strong causal association between glucuronate levels (odd ratio (OR) [95% CI]: 0.98 [0.97-0.99], p FDR = 0.002), adenosine 5'-monophosphate (AMP) to phosphate ratio (OR [95% CI]:0.58 [0.45-0.74], p FDR = 0.009), cysteinylglycine disulfide levels (OR [95% CI]: 0.85 [0.78-0.92], p FDR = 0.047) and CTS was finally identified.

Conclusion

In summary, the results of this study suggest that the identified glucuronate, the ratio of AMP to phosphate, and cysteinylglycine disulfide levels can be considered as metabolic biomarkers for CTS screening and prevention in future clinical practice, as well as candidate molecules for future mechanism exploration and drug target selection.

Causality of genetically proxied immunophenotypes on cardiovascular diseases: a Mendelian randomization study

Background

Cardiovascular diseases (CVDs) stand as the foremost global cause of mortality, prompting a growing interest in using the potential of immune cells for heart injury treatment. This study aims to assess the causal association between immune cells and CVDs.

Methods

A total of 731 immune cells were derived from a previously published genome-wide association study (GWAS), which included approximately 22 million genetic variants among 3,757 individuals of Sardinian ancestry. Genetic associations with atrial fibrillation (AF), heart failure, coronary artery disease, myocardial infarction and stroke were extracted from large-scale GWAS. A two-sample Mendelian randomization (MR) analysis was used to assess the causal association between immune cells and CVDs. Replication MR analysis based on FinnGen dataset and meta-analysis are sequentially conducted to validate causal relationships.

Results

Collectively, genetically predicted 4 immune cell traits were associated with AF and 5 immune cell traits were associated with stroke. Increased levels of IgD- CD38dim absolute count were associated with a higher susceptibility to AF, while increased expression of CD14+ CD16+ monocytes, CD62L on CD62L+ myeloid dendritic cells, and CD16 on CD14- CD16+ monocytes were linked to a decreased susceptibility to AF. Additionally, an elevated susceptibility to stroke was linked to an increase in the percentage of CD39+ resting Tregs and heightened CD27 expression on IgD- CD38+ cells. Conversely, a decreased susceptibility to stroke was associated with increased CD40 expression on monocytes, particularly on CD14+ CD16+ and CD14+ CD16- monocytes, with the latter two showing the most compelling evidence.

Conclusion

This study identified several immune cell traits that have a causal relationship with CVDs, thus confirming that immune cells play an important role in the pathogenesis of these diseases.

Differential expression of Semaphorin-7A /CD163-positive macrophages in large artery and cardiogenic stroke

BACKGROUND

Identification of the causes of stroke of undetermined etiology, specifically cardioembolism (CE) and non-CE causes, can inform treatment planning and prognosis prediction. The objective of this study was to analyze the disparities in thrombus composition, particularly Semaphorin-7A (Sema7A) and CD163, between patients diagnosed with large-artery atherosclerosis (LAA) and those with CE, and to investigate their potential association with prognosis.

METHODS

Thrombi were collected from patients who underwent mechanical thrombectomy at two hospitals. The patients were categorized into two groups: LAA and CE. We compared the levels of Sema7A and CD163 between these groups and analyzed their relationships with stroke severity, hemorrhagic transformation and prognosis.

RESULTS

The study involved a total of 67 patients. Sema7A expression was found to be significantly higher in the CE group compared to LAA (p < 0.001). Conversely, no statistically significant differences were observed for CD163 between the groups. The presence of Sema7A/CD163 did not show any associations with stroke severity or hemorrhagic transformation (all p > 0.05). However, both Sema7A (OR, 2.017; 95% CI, 1.301-3.518; p = 0.005) and CD163 (OR, 2.283; 95% CI, 1.252-5.724; p = 0.03) were associated with the poor prognosis for stroke, after adjusting for stroke severity.

CONCLUSION

This study highlights that CE thrombi exhibited higher levels of Sema7A expression compared to LAA thrombi. Moreover, we found a positive correlation between Sema7A/CD163 levels and the poor prognosis of patients with acute ischemic stroke.

Targeting Cysteine Oxidation in Thrombotic Disorders

Oxidative stress increases the risk for clinically significant thrombotic events, yet the mechanisms by which oxidants become prothrombotic are unclear. In this review, we provide an overview of cysteine reactivity and oxidation. We then highlight recent findings on cysteine oxidation events in oxidative stress-related thrombosis. Special emphasis is on the signaling pathway induced by a platelet membrane protein, CD36, in dyslipidemia, and by protein disulfide isomerase (PDI), a member of the thiol oxidoreductase family of proteins. Antioxidative and chemical biology approaches to target cysteine are discussed. Lastly, the knowledge gaps in the field are highlighted as they relate to understanding how oxidative cysteine modification might be targeted to limit thrombosis.

Dynamic and Rapid Detection of Guanosine during Ischemia

Guanosine acts in both neuroprotective and neurosignaling pathways in the central nervous system; in this paper, we present the first fast voltammetric measurements of endogenous guanosine release during pre- and post-ischemic conditions. We discuss the metric of our measurements via analysis of event concentration, duration, and interevent time of rapid guanosine release. We observe changes across all three metrics from our normoxic to ischemic conditions. Pharmacological studies were performed to confirm that guanosine release is a calcium-dependent process and that the signaling observed is purinergic. Finally, we show the validity of our ischemic model via staining and fluorescent imaging. Overall, this paper sets the tone for rapid monitoring of guanosine and provides a platform to investigate the extent to which guanosine accumulates at the site of brain injury, i.e., ischemia.