Novel insight into circular RNA HECTD1 in astrocyte activation via autophagy by targeting MIR142-TIPARP: implications for cerebral ischemic stroke

Autophagy: a double-edged sword in ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury describes the pathological process wherein tissue damage, initially caused by insufficient blood supply (ischemia), is exacerbated upon the restoration of blood flow (reperfusion). This phenomenon can lead to irreversible tissue damage and is commonly observed in contexts such as cardiac surgery and stroke, where blood supply is temporarily obstructed. During ischemic conditions, the anaerobic metabolism of tissues and organs results in compromised enzyme activity. Subsequent reperfusion exacerbates mitochondrial dysfunction, leading to increased oxidative stress and the accumulation of reactive oxygen species (ROS). This cascade ultimately triggers cell death through mechanisms such as autophagy and mitophagy. Autophagy constitutes a crucial catabolic mechanism within eukaryotic cells, facilitating the degradation and recycling of damaged, aged, or superfluous organelles and proteins via the lysosomal pathway. This process is essential for maintaining cellular homeostasis and adapting to diverse stress conditions. As a cellular self-degradation and clearance mechanism, autophagy exhibits a dualistic function: it can confer protection during the initial phases of cellular injury, yet potentially exacerbate damage in the later stages. This paper aims to elucidate the fundamental mechanisms of autophagy in I/R injury, highlighting its dual role in regulation and its effects on both organ-specific and systemic responses. By comprehending the dual mechanisms of autophagy and their implications for organ function, this study seeks to explore the potential for therapeutic interventions through the modulation of autophagy within clinical settings.

Emerging role and clinical applications of circular RNAs in human diseases

Circular RNAs (circRNAs) are a large family of non-coding RNAs characterized by a single-stranded, covalently closed structure, predominantly synthesized through a back-splicing mechanism. While thousands of circRNAs have been identified, only a few have been functionally characterized. Although circRNAs are less abundant than other RNA types, they exhibit exceptional stability due to their covalently closed structure and demonstrate high cell and tissue specificity. CircRNAs play a critical role in maintaining cellular homeostasis by influencing gene transcription, translation, and post-translation processes, modulating the immune system, and interacting with mRNA, miRNA, and proteins. Abnormal circRNA expression has been associated with a wide range of human diseases and various infections. Due to their remarkable stability in body fluids and tissues, emerging research suggests that circRNAs could serve as diagnostic and therapeutic biomarkers for these diseases. This review focuses on the emerging role of circRNAs in various human diseases, exploring their biogenesis, molecular functions, and potential clinical applications as diagnostic and therapeutic biomarkers with current evidence, challenges, and future perspectives. The key theme highlights the significance of circRNAs in regulating gene expression, their involvement in diseases like cancer, neurodegenerative disorders, cardiovascular diseases, and diabetes, and their potential use in translational medicine for developing novel therapeutic strategies. We also discuss recent clinical trials involving circRNAs. Thus, this review is important for both basic researchers and clinical scientists, as it provides updated insights into the role of circRNAs in human diseases, aiding further exploration and advancements in the field.

Impact of different doses of intravenous alteplase on neuroinjury biomarker levels in patients with acute ischemic stroke and stress hyperglycemia

Intravenous alteplase thrombolysis is a primary treatment for acute ischemic stroke (AIS), but the optimal dose remains uncertain in patients with stress hyperglycemia. This study aims to compare the changes in neuroinjury biomarker levels, as well as the efficacy and safety, between low-dose (0.6 mg/kg) and standard-dose (0.9 mg/kg) intravenous alteplase treatment in patients with AIS and stress hyperglycemia. This study included 150 patients with AIS and stress hyperglycemia, who were divided into a low-dose group (n = 78) and a standard-dose group (n = 72). Differences between the 2 groups were analyzed in terms of neuroinjury biomarkers (neuro-specific enolase, S100β, glial fibrillary acidic protein, myelin basic protein), neurological recovery (National Institutes of Health Stroke Scale score), clinical outcomes (modified Rankin Scale score), and the incidence of adverse events. Multivariate regression analysis was conducted to evaluate the relationship between the dose and a favorable prognosis (modified Rankin Scale ≤ 2). We found that, within 24 hours post-treatment, the levels of neuroinjury biomarkers (neuro-specific enolase, S100β, glial fibrillary acidic protein, myelin basic protein) were significantly lower in the low-dose group compared with the standard-dose group (P < .05), and the improvement in National Institutes of Health Stroke Scale scores was more pronounced (P < .01). Three months after thrombolysis, the favorable prognosis rate in the low-dose group was 63.5%, higher than the 47.2% in the standard-dose group, with a near-significant difference (P = .09). Multivariate regression analysis indicated that low-dose treatment was an independent protective factor for a favorable prognosis (odds ratio = 2.34, 95% confidence interval = 1.29-4.23, P = .006). There were no significant differences in the incidence of adverse events between the 2 groups, though the proportion of mild bleeding was slightly lower in the low-dose group compared with the standard-dose group. Low-dose intravenous alteplase thrombolysis demonstrates more significant neuroprotective effects in patients with AIS and stress hyperglycemia, promoting neurological recovery and improving long-term prognosis without increasing the risk of adverse events. Low-dose thrombolysis may be a safer and more effective treatment option, but its efficacy and safety require further validation through large-scale, randomized controlled trials.

SARM1 deletion inhibits astrogliosis and BBB damage through Jagged-1/Notch-1/NF-κB signaling to improve neurological function after ischemic stroke

Reactive astrogliosis is a critical process in the development of ischemic stroke. However, the precise mechanism by which reactive astrogliosis changes the pathogenesis of ischemic stroke remains elusive. Sterile alpha and TIR motif-containing 1 protein (SARM1) plays a key role in axonal degeneration and is involved in different cell death programs that regulate neuronal survival. The present study investigated the role of SARM1 in regulating reactive astrogliosis and neurological function after stroke in whole-body SARM1 knockout (SARM1-/-) mice. SARM1-/- mice showed significantly smaller infarction, slighter apoptosis, and fewer neurological function deficits 1-7 days after ischemic injury. Immunohistochemistry, western blot, and real-time PCR analyses revealed that compared with the wild-type (WT) mice, SARM1-/- mice exhibited reduced astrocytic proliferation, increased anti-inflammatory astrocytes, decreased glial scar formation in the infarct zone on day 7 after ischemic injury. SARM1 deletion also suppressed cerebral microvascular damage and blood-brain barrier (BBB) injury in ischemic brains. Mechanistically, SARM1 deletion inhibited the stroke-triggered activation of NF-κB signaling and decreased the expression of Jagged-1 and NICD in astrocytes. Overall, these findings provide the first line of evidence for a causative role of SARM1 protein in ischemia-induced reactive astrogliosis and ischemic neurovascular damage.

Targeting intracellular autophagic process for the treatment of post-stroke ischemia/reperfusion injury

Cerebral ischemia/reperfusion (I/R) injury is an important pathophysiological condition of ischemic stroke that involves a variety of physiological and pathological cell death pathways, including autophagy, apoptosis, necroptosis, and phagoptosis, among which autophagy is the most studied. We have reviewed studies published in the past 5 years regarding the association between autophagy and cerebral I/R injury. To the best of our knowledge, this is the first review article summarizing potential candidates targeting autophagic pathways in the treatment of I/R injury post ischemic stroke. The findings of this review may help to better understand the pathogenesis and mechanisms of I/R events and bridge the gap between basic and translational research that may lead to the development of novel therapeutic approaches for I/R injury.

LncRNA TUG1 Repressed Angiogenesis by Promoting the Ubiquitination of HuR and Inhibiting Its Nuclear Translocation in Cerebral Ischemic Reperfusion Injury

Although both Taurine Upregulated Gene 1(TUG1) and Human Antigen R (HuR) play significant regulatory roles in Cerebral Ischemic Reperfusion Injury (CIRI), their potential pro-angiogenesis mechanisms in CIRI remain unclear.

METHODS

Herein, the biological roles of TUG1 and HuR in angiogenesis are first confirmed. Following that, HuR-binding VEGFA mRNAs are identified via the Fluorescence In Situ Hybridization (FISH), RNA Immunoprecipitation (RIP), and Cross-Linking Immunoprecipitation (CLIP) assays. Actinomycin D and polysomal assays are also employed to confirm VEGFA mRNA stability. The co-localization of TUG1 with HuR is confirmed using FISH, while the RIP and RNA pull-down assays are employed to elucidate their interplay. The direct binding between TUG1 and HuR is confirmed through the CLIP assay. Co-Immunoprecipitation (Co-IP) and rescue experiments are performed to further elucidate TUG1-HuR interactions.

RESULTS

While TUG1 repressed angiogenesis and aggravated CIRI, HuR exerted contrary effects. Specifically, HuR bound directly to VEGFA mRNA, a phenomenon that enhanced VEGFA mRNA stability. Conversely, TUG1 binds to HuR directly, inhibiting its nuclear translocation and promoting its ubiquitination, ultimately reducing VEGFA mRNA stability.

CONCLUSIONS

It is found that TUG1 can inhibit angiogenesis in CIRI through the HuR/VEGFA mRNA axis.

Diagnostic significance of serum hsa_circ_0000745 and hsa_circ_0001459 in ischemic stroke and its role in the prognosis of interventional therapy

OBJECTIVE

We aimed to identify hsa_circ_0000745 and hsa_circ_0001459 expression, value as biomarkers in ischemic stroke (IS), and functions in BV2 cells.

METHODS

RNA sequencing datasets in the GEO database were retrieved. The expression of circulating hsa_circ_0000745 and hsa_circ_0001459 was validated by RT-qPCR. The predictive values of hsa_circ_0000745 and hsa_circ_0001459 in the diagnosis and outcome of acute IS were evaluated using receiver operator characteristic curve analysis. BV2 cells were treated with lipopolysaccharide, followed by hsa_circ_0000745 or hsa_circ_0001459 downregulation and subsequent migration and apoptosis assay. The downstream miR-1287-5p was detected using the luciferase reporter gene assay.

RESULTS

Hsa_circ_0000745 or hsa_circ_0001459 were upregulated in acute IS. Hsa_circ_0000745 or/and hsa_circ_0001459 differentiated between healthy control subjects and patients with IS, resulting in areas under curve (AUC) of 0.85 and 0.83, respectively. Hsa_circ_0000745 or hsa_circ_0001459 was positively correlated with serum pro-inflammatory cytokines and the NIHSS (P<0.001). Longitudinal and ROC analyses of hsa_circ_0001459 and hsa_circ_0000745 expression levels revealed the 90-day-outcome-predicting potential after stroke. Hsa_circ_0001459 and hsa_circ_0000745 promoted the apoptosis and inhibited the migration of LPS-induced BV2 cells. Hsa_circ_0001459 and hsa_circ_0000745 commonly sponged miR-1287-5p.

CONCLUSIONS

Hsa_circ_0001459 and hsa_circ_0000745 showed upregulations in IS and might have clinical utility as a diagnostic and outcome-predicting marker.

The roles and therapeutic potential of exosomal non-coding RNAs in microglia-mediated intercellular communication

Exosomes, which are small extracellular vesicles (sEVs), serve as versatile regulators of intercellular communication in the progression of various diseases, including neurological disorders. Among the diverse array of cargo they carry, non-coding RNAs (ncRNAs) play key regulatory roles in various pathophysiological processes. Exosomal ncRNAs derived from distinct cells modulate their reciprocal crosstalk locally or remotely, thereby mediating neurological diseases. Nevertheless, the emerging role of exosomal ncRNAsin microglia-mediated phenotypes remains largely unexplored. This review aims to summarise the biological functions of exosomal ncRNAs and the molecular mechanisms that underlie their impact on microglia-mediated intercellular communication, modulating neuroinflammation and synaptic functions within the landscape of neurological disorders. Furthermore, this review comprehensively described the potential applications of exosomal ncRNAs as diagnostic and prognostic biomarkers, as well as innovative therapeutic targets for the treatment of neurological diseases.

Identification of a circRNA-mediated immune-related ceRNA network and circRNAs as diagnostic biomarkers in acute ischemic stroke

BACKGROUND

Research has demonstrated that circular RNAs (circRNAs) play important roles in acute ischemic stroke (AIS). However, the functions of circRNA-mediated competitive endogenous RNA (ceRNA) in AIS-related immunological inflammation are not well understood. In our study, we aimed to construct a circRNA-mediated immune-related ceRNA network and identify diagnostic circRNAs for AIS.

METHODS

R software was used to analyze the microarray data obtained from the GEO database. The bioinformatics database was then used to develop the circRNA-mediated ceRNA network. A topological property study of the ceRNA network was performed to identify new circRNAs. Subsequently, we validated the potential circRNAs in both mice middle cerebral artery occlusion (MCAO) model and clinical samples obtained from our center with quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

An AIS immune-related ceRNA (AISIRC) network was constructed, comprising immune-related genes (IRGs), circRNAs, and miRNAs. A subnetwork was then extracted from the AISIRC network and we identified seven circRNAs associated with immune response. The qRT-PCR assays were conducted to validate the circRNAs candidate using blood samples from MCAO mice. The results demonstrated that circulating circOXCT1 and circSLC8A1 were significantly up-regulated in AIS patients. Receiver-operating characteristic (ROC) curve analyses and logistic regression demonstrated the perfect predictive and discriminative features of these two circRNAs biomarkers in AIS. Longitudinal analysis of circRNA expression after AIS indicated the promising potential of circSLC8A1 for monitoring AIS progression and dynamics.

CONCLUSION

We successfully constructed circRNA-mediated immune-related ceRNA network and identified two circulating circRNAs (circOXCT1 and circSLC8A1), which showed high diagnostic sensitivity for AIS.

CircKat6b Mediates the Antidepressant Effect of Esketamine by Regulating Astrocyte Function

The abundant expression of circular RNAs (circRNAs) in the central nervous system and their contribution to the pathogenesis of depression suggest that circRNAs are promising therapeutic targets for depression. This study explored the role and mechanism of circKat6b in esketamine's antidepressant effect. We found that intravenous administration of esketamine (5 mg/kg) treatment decreased the circKat6b expression in the astrocytes of hippocampus induced by a chronic unpredictable mild stress (CUMS) mouse model, while the overexpression of circKat6b in the hippocampus significantly attenuated the antidepressant effects of esketamine in depressed mice. RNA-sequencing, RT-PCR, and western blot experiments showed that the stat1 and p-stat1 expression were significantly upregulated in mouse astrocytes overexpressing circKat6b. In the CUMS mouse model, overexpression of circKat6b in the hippocampus significantly reversed the downregulation of p-stat1 protein expression caused by esketamine. Our findings demonstrated that a novel mechanism of the antidepressant like effect of esketamine may be achieved by reducing the expression of circKat6b in the astrocyte of the hippocampus of depressed mice.

Protective effects of PIK3CG knockdown against OGD/R-induced neuronal damage via inhibition of autophagy through the AMPK/mTOR pathway

BACKGROUND

Ischemic stroke represents an urgent need for more efficacious therapies owing to modest effectiveness of current treatment.

METHODS

Download data from stroke patients and collect blood samples from clinical patients to analyze phosphatidylinositol-3 kinase catalytic subunit γ (PIK3CG) expression. To establish a brain damage model, oxygen glucose deprivation/reperfusion (OGD/R) was applied to SH-SY5Y cells. Impact of PIK3CG on AMPK/mTOR autophagy pathway was verified treating cells with AMPK activator metformin. Proliferation and apoptosis were identified by CCK8 and flow cytometry.

RESULTS

Differential expression analysis and clinical testing show that PIK3CG is highly expressed in patients. Prolonged ODG/R exposure increased PIK3CG levels, supressed cell proliferation, and induced apoptosis. KEGG pathway analysis implicated PIK3CG in autophagy pathway. Knockdown of PIK3CG supressed OGD/R-induced reductions in cell proliferation and OGD/R-induced increases in apoptosis and expressions of Beclin 1 and LC3 II. Following OGD/R, AMPK phosphorylation was upregulated while mammalian target of rapamycin (mTOR) phosphorylation was downregulated, indicating AMPK/mTOR autophagy activation. Knockdown of PIK3CG opposed metformin-induced rises in Beclin 1, LC3 II and apoptosis along with decreases in proliferation.

CONCLUSION

PIK3CG knockdown protects neuronal cells by inhibiting AMPK/mTOR autophagy pathway and further inhibiting autophagy.

Non-coding RNAs in acute ischemic stroke: from brain to periphery

Acute ischemic stroke is a clinical emergency and a condition with high morbidity, mortality, and disability. Accurate predictive, diagnostic, and prognostic biomarkers and effective therapeutic targets for acute ischemic stroke remain undetermined. With innovations in high-throughput gene sequencing analysis, many aberrantly expressed non-coding RNAs (ncRNAs) in the brain and peripheral blood after acute ischemic stroke have been found in clinical samples and experimental models. Differentially expressed ncRNAs in the post-stroke brain were demonstrated to play vital roles in pathological processes, leading to neuroprotection or deterioration, thus ncRNAs can serve as therapeutic targets in acute ischemic stroke. Moreover, distinctly expressed ncRNAs in the peripheral blood can be used as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. In particular, ncRNAs in peripheral immune cells were recently shown to be involved in the peripheral and brain immune response after acute ischemic stroke. In this review, we consolidate the latest progress of research into the roles of ncRNAs (microRNAs, long ncRNAs, and circular RNAs) in the pathological processes of acute ischemic stroke-induced brain damage, as well as the potential of these ncRNAs to act as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. Findings from this review will provide novel ideas for the clinical application of ncRNAs in acute ischemic stroke.

Bibliometric Analysis of Non-coding RNAs and Ischemic Stroke: Trends, Frontiers, and Challenges

More and more articles have shown that non-coding RNAs (ncRNAs) play a significant role in the pathogenesis and prognosis of ischemic stroke. However, the bibliometric analysis in ncRNAs and ischemic stroke is still lacking. This study retrieved the Web of Science Core Collection for relevant articles from January 1, 2010 to April 6, 2023. Bibliometrix R, VOSviewer, and CiteSpace were used to perform the bibliometric analysis. A total of 1058 articles were eligible for this review. The number of publications showed a fluctuating upward trend. The total citations were 28,698 times, and the average number of citations per article was 27.12 times. Our findings indicated ncRNAs has been increasingly investigated for its critical role in apoptosis, autophagy, angiogenesis, inflammation, oxidative stress, and blood-brain barrier after ischemic stroke by regulating target mRNAs, extracellular secretion, target proteins, and others. The microRNAs, circular RNAs, and long ncRNAs may be hotspots, and ferroptosis, METTL3, and exosome might be frontier in this field. Besides, ncRNAs have a promising future as diagnostic and prognostic biomarkers, molecular drug targets, and other targeted therapies for ischemic stroke. However, it still faces many challenges to be successfully applied in the clinical practice.

CircFndc3b Mediates Exercise-Induced Neuroprotection by Mitigating Microglial/Macrophage Pyroptosis via the ENO1/KLF2 Axis in Stroke Mice

Circular RNA (circRNA) plays a pivotal role in regulating neurological damage post-ischemic stroke. Previous researches demonstrated that exercise mitigates neurological dysfunction after ischemic stroke, yet the specific contributions of circRNAs to exercise-induced neuroprotection remain unclear. This study reveals that mmu_circ_0001113 (circFndc3b) is markedly downregulated in the penumbral cortex of a mouse model subjected to middle cerebral artery occlusion (MCAO). However, exercise increased circFndc3b expression in microglia/macrophages, alleviating pyroptosis, reducing infarct volume, and enhancing neurological recovery in MCAO mice. Mechanistically, circFndc3b interacted with Enolase 1 (ENO1), facilitating ENO1's binding to the 3' Untranslated Region (3'UTR) of Krüppel-like Factor 2 (Klf2) mRNA, thereby stabilizing Klf2 mRNA and increasing its protein expression, which suppressed NOD-like Receptor Family Pyrin Domain Containing 3 (NLRP3) inflammasome-mediated microglial/macrophage pyroptosis. Additionally, circFndc3b enhanced ENO1's interaction with the 3'UTR of Fused in Sarcoma (FUS) mRNA, leading to increased FUS protein levels and promoting circFndc3b cyclization. These results suggest that circFndc3b mediates exercise-induced anti-pyroptotic effects via the ENO1/Klf2 axis, and a circFndc3b/ENO1/FUS positive feedback loop may potentiate exercise's neuroprotective effects. This study unveils a novel mechanism underlying exercise-induced neuroprotection in ischemic stroke and positions circFndc3b as a promising therapeutic target for stroke management, mimicking the beneficial effects of exercise.

Membrane Associated RNA-Containing Vesicles Regulate Cortical Astrocytic Microdomain Calcium Transients in Awake Ischemic Stroke Mice

Astrocytic processes minutely regulate neuronal activity via tripartite synaptic structures. The precision-tuning of the function of astrocytic processes is garnering increasing attention because of its significance in promoting brain repair following ischemic stroke. Microdomain calcium (Ca2+) transients in astrocytic processes are pivotal for the functional regulation of these processes. However, the understanding of the alterations and regulatory mechanism of microdomain Ca2+ transients during stroke remains limited. In the present study, a fast high-resolution, miniaturized two-photon microscopy is used to show that the levels of astrocytic microdomain Ca2+ transients are significantly reduced in the peri-infarct area of awake ischemic stroke mice. This finding correlated with the behavioral deficits shown by these mice under freely-moving conditions. Mitochondrial Ca2+ activity is an important factor driving the microdomain Ca2+ transients. DEAD Box 1 (DDX1) bound to circSCMH1 (a circular RNA involved in vascular post-stroke repair) facilitates the formation of membrane-associated RNA-containing vesicles (MARVs) and enhances the activity of astrocytic microdomain Ca2+ transients, thereby promoting behavioral recovery. These results show that targeting astrocytic microdomain Ca2+ transients is a potential therapeutic approach in stroke intervention.

TGN-020 ameliorates motor dysfunction post-spinal cord injury via enhancing astrocyte autophagy and mitigating inflammation by activating AQP4/PPAR-γ/mTOR pathway

Spinal Cord Injury (SCI) is a severe condition that often leads to substantial neurological impairments. This study aimed to explore the role of Aquaporin-4 (AQP4) in regulating astrocyte autophagy and neuroinflammation post-SCI, as well as to evaluate the therapeutic potential of AQP4 inhibition using the specific inhibitor TGN-020. Using Western blot, CCK8 assays, immunofluorescence staining, histopathological assessments, and behavioral analyses, we investigated the effects of TGN-020 on SCI-induced alterations in autophagy, neuroinflammation, astrocyte proliferation, neuronal damage, and motor function recovery in both rat and astrocyte models. Our findings indicate that TGN-020 significantly enhances astrocyte autophagy, reduces neuroinflammation, thereby leading to mitigated astrocyte activation by suppressing AQP4 expression. These beneficial effects are associated with the activation of the peroxisome proliferator-activated receptor-γ/mammalian target of rapamycin (PPAR-γ/mTOR) signaling pathway. Notably, the introduction of the PPAR-γ specific inhibitor GW9662 abrogated the positive regulatory effects of TGN-020 on SCI-induced autophagy and neuroinflammation. Collectively, our in vivo and in vitro experiments demonstrate that TGN-020, by down-regulating AQP4, activates the PPAR-γ/mTOR pathway, ameliorates astrocyte autophagy, diminishes neuroinflammation, and ultimately enhances motor function recovery.

New TIPARP inhibitor rescues mitochondrial function and brain injury in ischemic stroke

Ischemic stroke is a high-mortality disease that urgently requires new therapeutic strategies. Insufficient cerebral blood supply can induce poly (ADP-ribose) polymerase (PARP) activation and mitochondrial dysfunction, leading to tissue damage and motor dysfunction. We demonstrate that the expression of TCDD inducible PARP (TIPARP) is elevated in ischemic stroke patients and mice. Knockdown of Tiparp reduces brain infarction and promotes recovery of motor function in ischemic stroke mice. A rationally designed TIPARP inhibitor, XG-04-B1, promotes repair of brain injury and recovery of motor function in ischemic stroke mice. Mechanistically, XG-04-B1 increases neuronal plasticity and inhibits astrocyte activation in ischemic stroke mice. In addition, eukaryotic translation initiation factor 3 subunit B (EIF3B) is a direct target of TIPARP. TIPARP interacts with EIF3B through nucleoplasmic redistribution, leading to mitochondrial dysfunction. Knockdown of Tiparp and inhibition of TIPARP via XG-04-B1 restore mitochondrial homeostasis in ischemic stroke mice. Taken together, TIPARP activation contributes to mitochondrial dysfunction and subsequent brain injury, and is therefore a promising therapeutic target for stroke.

CircRNA-mediated regulation of cardiovascular disease

Cardiovascular diseases (CVDs) encompass a range of disorders affecting the heart and blood vessels, such as coronary heart disease, cerebrovascular disease (e.g., stroke), peripheral arterial disease, congenital heart anomalies, deep vein thrombosis, and pulmonary embolism. CVDs are often referred to as the leading cause of mortality worldwide. Recent advancements in deep sequencing have unveiled a plethora of noncoding RNA transcripts, including circular RNAs (circRNAs), which play pivotal roles in the regulation of CVDs. A decade of research has differentiated various circRNAs by their vasculoprotective or deleterious functions, revealing potential therapeutic targets. This review provides an overview of circRNAs and a comprehensive examination of CVDs, the regulatory circRNAs within the vasculature, and the burgeoning research domain dedicated to these noncoding RNAs.

M1 Microglia-Derived Exosomes Promote A1 Astrocyte Activation and Aggravate Ischemic Injury via circSTRN3/miR-331-5p/MAVS/NF-κB Pathway

Background

After ischemic stroke (IS), microglia and astrocytes undergo polarization, transforming into a pro-inflammatory phenotype (M1 or A1). According to previous studies, exosomes might play an important role in the interplay between M1 microglia and A1 astrocytes after IS.

Methods

We used the microglial oxygen-glucose deprivation/reperfusion (OGD/R) model and ultracentrifugation to extract M1 microglial exosomes (M1-exos). Subsequently, we identified circSTRN3 enriched in exosomes through RNA sequencing and detected the role of circSTRN3 in astrocyte activation based on bioinformatics analysis, immunofluorescence, Western blotting, and polymerase chain reaction analysis. We validated these findings in the middle cerebral artery occlusion/reperfusion (MCAO/R) model of adult male C57BL/6J mice. Finally, we confirmed the correlation among circSTRN3, miR-331-5p, and stroke severity score in exosomes isolated from peripheral blood of IS patients.

Results

Our findings revealed that M1-exos promoted A1 astrocyte activation. CircSTRN3 was abundant in M1-exos, which could sponge miR-331-5p to affect mitochondrial antiviral signaling protein (MAVS), activate NF-κB pathway, and participate in A1 astrocyte activation. In addition, overexpressed circSTRN3 augmented the infarct size and neurological dysfunction in MCAO/R models, while miR-331-5p mimics reversed the effect. Furthermore, circSTRN3 in IS patients was positively correlated with stroke severity score (R 2 = 0.83, P < 0.001), while miR-331-5p demonstrated a negative correlation with the same score (R 2 = 0.81, P < 0.001).

Conclusion

Taken together, our research indicated that circSTRN3 from M1-exos could promote A1 astrocyte activation and exacerbate ischemic brain injury via miR331-5p/MAVS/NF-κB axis.

Diallyl trisulfide regulates PGK1/Nrf2 expression and reduces inflammation to alleviate neurological damage in mice after traumatic brain injury

BACKGROUND

Diallyl trisulfide (DATS) has a direct antioxidant capacity and emerges as a promising neuroprotective agent. This study was designed to investigate the role of DATS in traumatic brain injury (TBI).

METHODS

TBI mouse models were established using the controlled cortical impact, followed by DATS administration. The effects of DATS on neurological deficit, brain damage, inflammation and phosphoglycerate kinase 1 (PGK1) expression were detected using mNSS test, histological analysis, TUNEL assay, enzyme-linked immunosorbent assay and immunofluorescence. PC12 cells were subjected to H2O2-induced oxidative injury after pre-treatment with DATS, followed by cell counting kit-8 assay, flow cytometry and ROS production detection. Apoptosis-related proteins and the PGK1/nuclear factor erythroid-2 related factor 2 (Nrf2) pathway were examined using Western blot.

RESULTS

DATS ameliorated the cerebral cortex damage, neurological dysfunction and apoptosis, as well as decreased PGK1 expression and expressions of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α) in mice after TBI. DATS also enhanced viability, blocked apoptosis and inhibited ROS production in H2O2-induced PC12 cells. DATS downregulated Cleaved-Caspase3, Bax and PGK1 levels, and upregulated Bcl-2 and Nrf2 levels in TBI mouse models and the injured cells.

CONCLUSION

DATS regulates PGK1/Nrf2 expression and inflammation to alleviate neurological damage in mice after TBI.

Bone marrow mesenchymal stem cells with PTBP1 knockdown protect against cerebral ischemia-reperfusion injury by inhibiting ferroptosis via the JNK/P38 pathway in rats

Over the years, the neuroprotective potential of bone marrow mesenchymal stem cells (BMSCs) in acute ischemic stroke has attracted significant attention. However, BMSCs face challenges like short metabolic cycles and low survival rates post-transplant. Polypyrimidine tract-binding protein 1 (PTBP1) is an immunomodulatory RNA-binding protein that regulates the cell cycle and increases cell viability. This study investigated the protective effects and underlying mechanism of PTBP1 knockdown in BMSCs (PTBP1KD-BMSCs) following ischemia-reperfusion injury (IRI) in neurons. BMSCs were isolated from Sprague-Dawley rat femurs and characterized through flow cytometry and differentiation induction. PTBP1 knockdown inhibited BMSCs proliferation. Co-culture with PTBP1KD-BMSCs decreased reactive oxygen species (ROS) and malondialdehyde (MDA) levels, while increasing glutathione (GSH) production in oxygen and glucose deprivation/reperfusion-induced PC12 cells. Transcriptome sequencing analysis of PC12 cells suggested that the protective effect of PTBP1KD-BMSCs against injury may involve ferroptosis. Furthermore, western blotting showed upregulation of glutathione synthetase (GSS), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11) in PTBP1KD-BMSCs, known negative regulators of ferroptosis. Moreover, PTBP1KD-BMSCs inhibited p38MAPK and JNK activation. In addition, PTBP1KD-BMSCs transplantation into middle cerebral artery occlusion/reperfusion (MCAO/R) rats reduced cerebral infarction volume and improved neurological function. Immunofluorescence analysis confirmed the upregulation of GSS expression in neurons of the ischemic cortex, while immunohistochemistry indicated a downregulation of p-P38. These result suggest that PTBP1KD-BMSCs can alleviate neuronal IRI by reducing oxidative stress, inhibiting ferroptosis, and modulating the MAPK pathway, providing a theoretical basis for potential treatment strategies for cerebral IRI.

Circular RNA SCMH1 suppresses KMO expression to inhibit mitophagy and promote functional recovery following stroke

Rationale: Metabolic dysfunction is one of the key pathological events after ischemic stroke. Disruption of cerebral blood flow impairs oxygen and energy substrate delivery, leading to mitochondrial oxidative phosphorylation dysfunction and cellular bioenergetic stress. Investigating the effects of circSCMH1, a brain repair-related circular RNA, on metabolism may identify novel therapeutic targets for stroke treatment. Methods: CircSCMH1 was encapsulated into brain-targeting extracellular vesicles (EVs) mediated by rabies virus glycoprotein (RVG). Using a mouse model of photothrombotic (PT) stroke, we employed metabolomics and transcriptomics, combined with western blotting and behavioral experiments, to identify the metabolic targets regulated in RVG-circSCMH1-EV-treated mice. Additionally, immunofluorescence staining, chromatin immunoprecipitation (ChIP), pull-down, and western blotting were utilized to elucidate the underlying mechanisms. Results: The targeted delivery of circSCMH1 via RVG-EVs was found to promote post-stroke brain repair by enhancing mitochondrial fusion and inhibiting mitophagy through suppression of kynurenine 3-monooxygenase (KMO) expression. Mechanistically, circSCMH1 exerted its inhibitory effect on KMO expression by binding to the transcription activator STAT5B, thereby impeding its nuclear translocation. Conclusions: Our study reveals a novel mechanism by which circSCMH1 downregulates KMO expression, thereby enhancing mitochondrial fusion and inhibiting mitophagy, ultimately facilitating post-stroke brain repair. These findings shed new light on the role of circSCMH1 in promoting stroke recovery and underscore its potential as a therapeutic target for the treatment of ischemic stroke.

Transcription Factor TFAP2B Exerts Neuroprotective Effects Targeting BNIP3-Mediated Mitophagy in Ischemia/Reperfusion Injury

Cerebral ischemia-reperfusion injury (CIRI) leads to malignant brain edema, blood-brain barrier destruction, and neuronal apoptosis. N6-methyladenosine (m6A) RNA modification in CIRI was still limited explored. In this study, MeRIP- and RNA-sequencing were performed of middle cerebral artery occlusion and reperfusion (MCAO/R) rats to find novel potential molecular targets. Transcription factor TFAP2B stood out of which its m6A abundance decreased associated with a marked reduction of its mRNA based on cojoint interactive bioinformatics analysis of the MeRIP- and RNA-sequencing data. It was suggested TFAP2B could have a role in CIRI. Functionally, overexpression of TFAP2B in cultured primary neurons could effectively improve the cell survival and pro-survival autophagy in parallel with reduced cell apoptosis during OGD/R in vitro. Through the RNA-sequencing of TFAP2B overexpressed primary neurons and subsequent validation experiments, it was found that mitophagy receptor BNIP3 was one of the important targets of TFAP2B in OGD/R neurons through which TFAP2B could bind to its promoter region for transcriptional activation of BNIP3, thereby enhancing BNIP3-mediated mitophagy to protect against OGD/R injury of neurons. Lastly, TFAP2B was demonstrated to alleviate the MCAO/R damage to a certain extent in vivo. Although it failed to confirm TFAP2B dysregulation was m6A dependent in current research, this is the first research of TFAP2B in CIRI field with important guiding significance.

An engineered cellular carrier delivers miR-138-5p to enhance mitophagy and protect hypoxic-injured neurons via the DNMT3A/Rhebl1 axis

Mitophagy influences the progression and prognosis of ischemic stroke (IS). However, whether DNA methylation in the brain is associated with altered mitophagy in hypoxia-injured neurons remains unclear. Here, miR-138-5p was found to be highly expressed in exosomes secreted by astrocytes stimulated with oxygen and glucose deprivation/re-oxygenation (OGD/R), which could influence the recovery of OGD/R-injured neurons through autophagy. Mechanistically, miR-138-5p promotes the stable expression of Ras homolog enriched in brain like 1(Rhebl1) through DNA-methyltransferase-3a (DNMT3A), thereby enhancing ubiquitin-dependent mitophagy to maintain mitochondrial homeostasis. Furthermore, we employed glycosylation engineering and bioorthogonal click reactions to load mirna onto the surface of microglia and deliver them to injured region utilising the inflammatory chemotactic properties of microglia to achieve drug-targeted delivery to the central nervous system (CNS). Our findings demonstrate miR-138-5p improves mitochondrial function in neurons through the miR-138-5p/DNMT3A/Rhebl1 axis. Additionally, our engineered cell vector-targeted delivery system could be promising for treating IS. STATEMENT OF SIGNIFICANCE: In this study, we demonstrated that miR-138-5p in exosomes secreted by astrocytes under hypoxia plays a critical role in the treatment of hypoxia-injured neurons. And we find a new target of miR-138-5p, DNMT3A, which affects neuronal mitophagy and thus exerts a protective effect by regulating the methylation of Rbebl1. Furthermore, we have developed a carrier delivery system by combining miR-138-5p with the cell membrane of microglia and utilized the inflammatory chemotactic properties of microglia to deliver this system to the brain via intravenous injection. This groundbreaking study not only provides a novel therapeutic approach for ischemia-reperfusion treatment but also establishes a solid theoretical foundation for further research on targeted drug delivery for central nervous system diseases with promising clinical applications.

Body fluid multiomics in 3PM-guided ischemic stroke management: health risk assessment, targeted protection against health-to-disease transition, and cost-effective personalized approach are envisaged

Because of its rapid progression and frequently poor prognosis, stroke is the third major cause of death in Europe and the first one in China. Many independent studies demonstrated sufficient space for prevention interventions in the primary care of ischemic stroke defined as the most cost-effective protection of vulnerable subpopulations against health-to-disease transition. Although several studies identified molecular patterns specific for IS in body fluids, none of these approaches has yet been incorporated into IS treatment guidelines. The advantages and disadvantages of individual body fluids are thoroughly analyzed throughout the paper. For example, multiomics based on a minimally invasive approach utilizing blood and its components is recommended for real-time monitoring, due to the particularly high level of dynamics of the blood as a body system. On the other hand, tear fluid as a more stable system is recommended for a non-invasive and patient-friendly holistic approach appropriate for health risk assessment and innovative screening programs in cost-effective IS management. This article details aspects essential to promote the practical implementation of highlighted achievements in 3PM-guided IS management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00376-2.

NDRG2 regulates glucose metabolism and ferroptosis of OGD/R-treated astrocytes by the Wnt/β-catenin signaling

Ischemic stroke is one main type of cerebrovascular disorders with leading cause of death and disability worldwide. Astrocytes are the only nerve cell type storing glycogen in the brain, which regulate the glucose metabolism and handle the energy supply and survive of neurons. Astrocyte ferroptosis contributes to neuron injury in brain disorders. N-myc downstream-regulated gene 2 (NDRG2) has been implicated in the progression of brain diseases, including ischemic stroke. However, whether NDRG2 could affect the glucose metabolism and ferroptosis of astrocytes during ischemic stroke remains largely unknown. Mouse astrocytes were treated with oxygen-glucose deprivation/reoxygenation (OGD/R) to establish the in vitro model. Glial fibrillary acidic protein, NDRG2, Wnt3a and β-catenin expression levels were detected by immunofluorescence staining and western blot analyses. Glucose metabolism was investigated by glucose uptake, lactate production, nicotinamide adenine dinucleotide phosphate hydrogen/nicotinamide adenine dinucleotide phosphate (NADPH/NADP+), ATP and glycolysis enzymes (HK2, PKM2 and lactate dehydrogenase A [LDHA]) levels. Ferroptosis was assessed via reactive oxygen species (ROS), glutathione (GSH), iron and ferroptosis-related markers (GPX4 and PTGS2) contents. Glycolysis enzymes and ferroptosis-related markers levels were measured via western blot. NDRG2 expression was elevated in OGD/R-induced astrocytes. NDRG2 overexpression aggravated OGD/R-induced loss of glucose metabolism through reducing glucose uptake, lactate production, NADPH/NADP+ and ATP levels. NDRG2 upregulation exacerbated OGD/R-caused reduction of glycolysis enzymes (HK2, PKM2 and LDHA) levels. NDRG2 promoted OGD/R-induced ferroptosis of astrocytes by increasing ROS, iron and PTGS2 levels and decreasing GSH and GPX4 levels. NDRG2 overexpression enhanced OGD/R-induced decrease of Wnt/β-catenin signaling activation by reducing Wnt3a and β-catenin expression. NDRG2 silencing played an opposite effect. Inhibition of Wnt/β-catenin signaling activation by IWR-1 attenuated the influences of NDRG2 knockdown on glucose metabolism, glycolysis enzymes levels and ferroptosis. These findings demonstrated that NDRG2 contributes to OGD/R-induced inhibition of glucose metabolism and promotion of ferroptosis in astrocytes through inhibiting Wnt/β-catenin signaling activation, which might be associated with ischemic stroke progression.

Physical exercise-induced circAnks1b upregulation promotes protective endoplasmic reticulum stress and suppresses apoptosis via miR-130b-5p/Pak2 signaling in an ischemic stroke model

AIMS

Physical exercise (PE) can accelerate post-stroke recovery. This study investigated contributions of circRNAs to PE-induced improvements in post-stroke neurological function.

METHODS

Rats subjected to transient middle cerebral artery occlusion were left sedentary or provided running-wheel access for 4 weeks during recovery. CircRNAs from peri-infarct cortex were identified by high-throughput sequencing, and interactions with miRNAs by immunoprecipitation, fluorescence in suit hybridization, and dual-luciferase reporter assays. In vivo circRNA knockdown was achieved using shRNA-AAVs and in vitro overexpression by plasmid transfection. Transmission electron microscopy, western blotting, and TUNEL assays were conducted to explore circRNA contributions to endoplasmic reticulum (ER) stress and neuronal apoptosis. CircRNA levels were measured in plasma from stroke patients by qRT-PCR and associations with neurological scores assessed by Pearson's correlation analysis.

RESULTS

PE upregulated circAnks1b, reduced infarct volume, and mitigated neurological dysfunction, while circAnks1b knockdown exacerbated neurological dysfunction and increased infarct size despite PE. CircAnks1b sponged miR-130b-5p, thereby disinhibiting Pak2 expression. Conversely, Pak2 downregulation disrupted PE-mediated protective ER stress, leading to reduced IRE1/XBP1 and heightened apoptosis. Plasma circAnks1b was higher in stroke patients receiving PE than sedentary patients and correlated negatively with neurological scores.

CONCLUSIONS

CircAnks1b upregulation may be an effective therapeutic strategy for post-stroke recovery.

Expression profile of circular RNAs in blood samples of Northern Chinese males with intracerebral hemorrhage shows downregulation of hsa-circ-0090829

Circular RNAs (circRNAs) are involved in several neurological disorders; however, the mechanisms underlying their involvement remain to be clarified. We attempted to explore the expression profiles of circRNAs and their potential functions and mechanisms in the pathogenesis of intracerebral hemorrhage (ICH) in Northern Chinese males. The microarray results showed that 50 circRNAs were significantly upregulated, while 194 circRNAs were significantly downregulated in ICH patients compared with healthy controls (p < 0.05). After bioinformatics analysis, a circRNA-microRNA-messenger RNA network and a protein-protein interaction network were constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that the neurotrophin signaling pathway, long-term potentiation, and the mitogen-activated protein kinase pathway are potentially implicated in ICH pathophysiology. The quantitative real-time polymerase chain reaction results revealed that hsa-circ-0090829 was significantly downregulated in ICH. The receiver operating characteristic curve analysis showed that the area under the curve of hsa-circ-0090829 between ICH and healthy controls was 0.807. Furthermore, the dual-luciferase assay showed that hsa-circ-0090829 sponged miR-526b-5p. This study reports the altered expression of circRNAs and identifies the potential functions of these circRNAs in ICH. Our results may facilitate further mechanistic research on circRNAs in ICH and provide probable novel diagnostic biomarkers and therapeutic targets for ICH.

Astrocyte modulation in cerebral ischemia-reperfusion injury: A promising therapeutic strategy

Cerebral ischemia-reperfusion injury (CIRI) poses significant challenges for drug development due to its complex pathogenesis. Astrocyte involvement in CIRI pathogenesis has led to the development of novel astrocyte-targeting drug strategies. To comprehensively review the current literature, we conducted a thorough analysis from January 2012 to December 2023, identifying 82 drugs aimed at preventing and treating CIRI. These drugs target astrocytes to exert potential benefits in CIRI, and their primary actions include modulation of relevant signaling pathways to inhibit neuroinflammation and oxidative stress, reduce cerebral edema, restore blood-brain barrier integrity, suppress excitotoxicity, and regulate autophagy. Notably, active components from traditional Chinese medicines (TCM) such as Salvia miltiorrhiza, Ginkgo, and Ginseng exhibit these important pharmacological properties and show promise in the treatment of CIRI. This review highlights the potential of astrocyte-targeted drugs to ameliorate CIRI and categorizes them based on their mechanisms of action, underscoring their therapeutic potential in targeting astrocytes.

MiR-30c-5p-Targeted Regulation of GNAI2 Improves Neural Function Injury and Inflammation in Cerebral Ischemia-Reperfusion Injury

MiRNAs are related to neuronal proliferation and apoptosis following cerebral ischemia-reperfusion injury (CIRI). This study focused on miR-30c-5p in the disease. An oxygen-glucose deprivation/re-oxygenation (OGD/R) model was prepared in HT22 cells and transfected to overexpress miR-30c-5p and G Protein Subunit Alpha I2 (GNAI2) respectively or co-transfected to silence miR-30c-5p and GNAI2. Meanwhile, a middle cerebral artery occlusion (MCAO) model was constructed in mice, and miR-30c-5p and GNAI2 were silenced in vivo simultaneously. The mice were evaluated for neurological damage, apoptosis, and inflammation. HT22 cells were tested for cytotoxicity, proliferation, apoptosis, and inflammatory factors. The interaction between miR-30c-5p and GNAI2 was predicted, analyzed, and confirmed. MiR-30c-5p was found to be downregulated in both experimental models. miR-30c-5p reduced lactate dehydrogenase production, inflammatory response, inhibit apoptosis, and enhanced neuronal proliferation, while GNAI2 overexpression showed the opposite results. Downregulated miR-30c-5p worsened neurological function, apoptosis, and inflammation of MCAO mice while silencing GNAI2 attenuated the influence of downregulated miR-30c-5p. MiR-30c-5p can improve neuronal apoptosis and inflammatory response caused by CIRI and is neuroprotective by targeting GNAI2, providing a new target for treating CIRI.

The Roles of Non-coding RNA Targeting Astrocytes in Cerebral Ischemia

Astrocytes are key targets for treating cerebral ischemia in the central nervous system. Non-coding RNAs (ncRNAs) participate in the pathological processes of astrocytes in cerebral ischemia. Recent reports suggest that ncRNAs ameliorate the outcome of cerebral ischemia by mediating astrocytes' inflammatory reaction, oxidative stress, excitotoxicity, autophagy, and apoptosis. Reconstructing cellular systems might offer a promising strategy for treating cerebral ischemia. This review briefly discusses the potential of ncRNAs as drug targets and explores the molecular regulatory mechanisms through which ncRNAs target astrocytes in cerebral ischemia. It provides an overview of the current research, discusses ncRNAs' implications as clinical markers for cerebral ischemia, and anticipates that ongoing research on ncRNAs may contribute to novel therapeutic approaches for treating this condition.

Exosomes from circRNA-Ptpn4 can modify ADSC treatment and repair nerve damage caused by cerebral infarction by shifting microglial M1/M2 polarization

Adipose-derived stem cells (ADSCs) have been demonstrated to improve the microenvironment after a stroke. Increasing studies have confirmed that hypoxia pretreatment of ADSCs resulted in a better therapeutic effect, but the mechanism of treatment is unclear. We isolated ADSCs and exosomes. Then, constructed a middle cerebral artery occlusion (MCAO) mice model. High-throughput sequencing was used to identify the differential expression of circRNA. Immunofluorescence and ELISAs were used to detect the therapeutic effects of ADSC exosomes on MCAO. The luciferase reporter assay was used to detect the interaction relationships among circRNA-Ptpn4, miR-153-3p, and Nrf2. This study showed that exosomes from hypoxia pretreatment of ADSCs had significant effects in promoting functional recovery following in vivo MCAO, through suppressed inflammatory factor expression, and shifting the microglial from M1 to M2 polarization activation. The results showed that circRNA-Ptpn4 was highly expressed during hypoxia pretreatment of ADSCs exosomes. Exosomes from circ-Ptpn4-modified ADSCs had a greater ability to promote functional recovery. The circ-Ptpn4 delivered from ADSC exosomes induced microglia/macrophage polarization from M1 to M2 by suppressing miR-153-3p and enhancing Nrf2 expressions. Taken together, the results showed that exosomes from circRNA-Ptpn4 modified ADSC treatment repaired nerve damage caused by cerebral infarction by inducing microglial M1/M2 polarization.

Astragaloside IV protects brain cells from ischemia-reperfusion injury by inhibiting ryanodine receptor expression and reducing the expression of P-Src and P-GRK2

Astragaloside IV, a prime active component of Astragalus membranaceus, has potential as a neuroprotectant. We aimed to identify the active ingredients in A. membranaceus and assess if Astragaloside IV can improve cerebral ischemia-reperfusion injury (CIRI) cell apoptosis by reducing P-Src and P-GRK2 via ryanodine receptor (RyR) expression inhibition. We used bioinformatics analysis to examine the effects of A. membranaceus on ischemic stroke. We studied brain samples from middle cerebral artery occlusion (MCAO) mice treated with normal saline, Astragaloside IV, and sham mice for pathology and Western blot tests. We also tested PC12 cells in vitro with or without Astragaloside IV or GSK180736A using Western blotting and fluorescence assays. Our bioinformatics analysis suggested a possible association between A. membranaceus, calcium ion pathways, and apoptosis pathways. Western blot data indicated Astragaloside IV significantly decreased RyR, p-Src, and downstream phosphorylated GRK2, PLC, CaMKII, and IP3R levels in MCAO mice brains. Astragaloside IV also considerably inhibited pro-apoptotic and oxidative stress-associated proteins' expression while boosting anti-apoptotic protein expression. The results suggest Astragaloside IV can inhibit RyR expression, subsequently reducing brain cell apoptosis.

Vagus nerve stimulation (VNS) inhibits cardiac mast cells activation and improves myocardial atrophy after ischemic stroke

BACKGROUND

Ischemic stroke is one of the leading causes of chronic disability worldwide, and stroke-induced heart damage can lead to death. According to research, patients with a variety of brain disease have good clinical results after vagus nerve stimulation (VNS). After ischemic stroke, mast cells (MCs) degranulate and release a large number of mediators, which may cause systemic inflammation. Chymase secreted by MCs can increase the levels of pathological angiotensin II (AngⅡ), which plays a crucial role in the deterioration of heart disease. Our goal was to develop a minimally invasive, targeted, and convenient VNS approach to assess the impact of VNS and to clarify the relationship between VNS and MCs in the prognosis of patients with myocardial atrophy after acute ischemic stroke.

METHODS

In this study, we verified the role of VNS in the treatment of myocardial atrophy after stroke and its molecular mechanism using a rat model of middle cerebral artery occlusion (MCAO/r). Behavioral studies were assessed using neurobehavioral deficit scores. Enzyme-linked immunosorbent assays, immunofluorescence staining, Western blotting and qRT-PCR were used to analyze the expression levels of myocardial atrophy, MC and inflammatory markers in rat hearts.

RESULTS

VNS improved myocardial atrophy in MCAO/r rats, inhibited MC activation, reduced the expression of chymase and AngⅡ, and inhibited the expression of proinflammatory factors. The chymase activator C48/80 reversed these effects of VNS. Chymase activation inhibited the effect of VNS on myocardial atrophy in MCAO/r rats, increased AngⅡ expression and aggravated inflammation and autophagy. The myocardial atrophy of MCAO/r rats was improved after chymase inhibition, and AngⅡ expression, inflammation and autophagy were reduced. Our results suggest that VNS may reduce the expression of chymase and AngⅡ by inhibiting MC activation, thereby improving myocardial atrophy and reducing inflammation and autophagy in MCAO/r rats. Inhibition of MC activation may be an effective strategy for treating myocardial atrophy after stroke.

CONCLUSIONS

VNS inhibits MC activation and reduces the expression of chymase and AngII, thereby alleviating myocardial atrophy, inflammation and autophagy after stroke.

Circ_0008146 Exacerbates Ferroptosis via Regulating the miR-342-5p/ACSL4 Axis After Cerebral Ischemic/Reperfusion

Purpose

Acute ischemic stroke (AIS) has seriously threatened people's health worldwide and there is an urge need for early diagnosis and effective treatment of AIS. This research intended to clarify the regulatory role of circ_0008146/miR-342-5p/ACSL4 axis in AIS.

Methods

High-throughput small RNA sequencing analysis was adapted to identify differentially expressed miRNAs between the AIS and control group. The circ_0008146, miR-342-5p, and ACSL4 levels were detected by qRT-PCR. Middle cerebral artery occlusion/reperfusion (MCAO/R) models were constructed in C57BL/6J mice. Assay kits were used to determine Fe2+ levels and a battery of oxidative stress and lipid peroxidation indicators, including ROS, MDA, LPO, SOD and GSH/GSSG ratio. The protein levels of ACSL4 were measured by Western blot. The behavioral function was assessed using neurobehavioral tests. TTC staining was employed to visualize infarction size. Nissl staining was adapted to detect histopathological changes. Receiver operating characteristic curve and correlation analysis were applied to investigate the clinical value and association of miR-342-5p and ACSL4.

Results

A total of 44 AIS patients and 49 healthy controls were enrolled in our study. The small RNA sequencing unveiled a significant decrease in miR-342-5p levels in AIS patients. MiR-342-5p inhibited oxidative stress and RSL3-induced ferroptosis after cerebral ischemic/reperfusion injury in vivo by targeting ferroptosis-related gene ACSL4. Circ_0008146 acted as a sponge of miR-342-5p, and overexpression of circ_0008146 increased neurological deficits and brain injury in mice. Circ_0008146 contributed to ferroptosis in cerebral infarction via sponging miR-342-5p to regulate ACSL4. Plasma miR-342-5p and ACSL4 demonstrated significant correlation and good diagnostic value for AIS patients.

Conclusion

This study provides the first in vivo evidence to show that circ_0008146 exacerbates neuronal ferroptosis after AIS via the miR-342-5p/ACSL4 axis. Furthermore, miR-342-5p/ACSL4 axis holds promise as a viable therapeutic target and practical biomarkers for AIS patients.

Mechanisms of Postischemic Stroke Angiogenesis: A Multifaceted Approach

Ischemic stroke constitutes a significant global health care challenge, and a comprehensive understanding of its recovery mechanisms is imperative for the development of innovative therapeutic strategies. Angiogenesis, a pivotal element of ischemic tissue repair, facilitates the restoration of blood flow to damaged regions, thereby promoting neuronal regeneration and functional recovery. Nevertheless, the mechanisms underlying postischemic stroke angiogenesis remain incompletely elucidated. This review meticulously examines the constituents of the neurovascular unit, ion channels, molecular mediators, and signaling pathways implicated in angiogenesis following stroke. Furthermore, it delves into prospective therapeutic strategies informed by these factors. Our objective is to provide detailed and exhaustive information on the intricate mechanisms governing postischemic stroke angiogenesis, thus providing a robust scientific foundation for the advancement of novel neurorepair therapies.

CircTrim37 Ameliorates Intracerebral Hemorrhage Outcomes by Modulating Microglial Polarization via the miR-30c-5p/SOCS3 Axis

Circular RNAs (circRNAs) have been progressively recognized as critical regulators in the pathology and pathophysiology of central nervous system disease. However, the potential role of circRNAs in intracerebral hemorrhage (ICH) is still largely unclear. Here, we demonstrate that circTrim37 expression was significantly upregulated at 3 days after ICH by circular RNA microarray and qPCR assays. Overexpression of circTrim37 could significantly ameliorate brain injury volume, brain edema, neurologic deficits, and inflammation in vivo after ICH. CircTrim37 promotes M2 polarization while restrains M1 polarization in vitro. Furthermore, circTrim37 acts as an endogenous sponge for miR-30c-5p, thereby inhibiting miR-30c-5p activity, leading to the upregulation of SOCS3 and making the balance of microglial response towards an M2 phenotype. Taken together, our results indicate the participation of circTrim37 and its coupling mechanism in ICH and provide a novel therapeutic target for ICH.

Minimally invasive vagus nerve stimulation modulates mast cell degranulation via the microbiota-gut-brain axis to ameliorate blood-brain barrier and intestinal barrier damage following ischemic stroke

Mast cells (MCs) play a significant role in various diseases, and their activation and degranulation can trigger inflammatory responses and barrier damage. Several studies have indicated that vagus nerve stimulation (VNS) exerts ameliorates neurological injury, and regulates gut MC degranulation. However, there is limited research on the modulatory effect of VNS on MCs in both the gut and brain in brain ischemia-reperfusion (I/R) injury in this process. We aim to develop a minimally invasive, targeted and convenient VNS approach to assess the impact of VNS and to clarify the relationship between VNS and MCs on the prognosis of acute ischemic stroke. We utilized middle cerebral artery occlusion/reperfusion (MCAO/r) to induce brain I/R injury. After the experiment, the motor function and neurofunctional impairments of the rats were detected, and the gastrointestinal function, blood-brain barrier (BBB) and intestinal barrier damage, and systemic and local inflammation were evaluated by Nissl, TTC staining, Evans blue, immunofluorescence staining, transmission electron microscopy, western blot assays, ELISA, and fecal 16S rRNA sequencing methods. Our research confirmed that our minimally invasive VNS method is a novel approach for stimulating the vagus nerve. VNS alleviated motor deficits and gastrointestinal dysfunction while also suppressing intestinal and neuroinflammation. Additionally, VNS ameliorated gut microbiota dysbiosis in rats. Furthermore, our analysis indicated that VNS reduces chymase secretion by modulating MCs degranulation and improves intestinal and BBB damage. Our results showed that VNS treatment can alleviate the damage of BBB and colonic barrier after cerebral I/R by modulating mast cell degranulation, and alleviates systemic inflammatory responses.

Circ_0000115 Protects Against Cerebral Ischemia Injury by Suppressing Neuronal Apoptosis, Oxidative Stress and Inflammation by miR-1224-5p/Nos3 Axis In Vitro

Cerebral ischemia is a severe neurological disability related to neuronal apoptosis and cellular stress response. Circular RNAs (circRNAs) are emerging regulators of cerebral ischemia. Herein, this study proposed to probe the action of circ_0000115 in cerebral ischemia injury. The mouse neuroblastoma cells N2a and HT22 underwent oxygen-glucose deprivation (OGD) were used as a model of in vitro cerebral ischemia. Levels of genes and proteins were detected by qRT-PCR and western blotting. Cell proliferation and apoptosis were determined by EdU assay and flow cytometry. Western blotting was used to detect the protein level of pro-inflammatory factors. The oxidative stress injury was evaluated by detecting reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) generation. Dual-luciferase reporter and RIP assays were used to confirm the target relationship between miR-1224-5p and circ_0000115 or nitric oxide synthase 3 (NOS3). OGD exposure decreased circ_0000115 and NOS3 expression, and increased miR-1224-5p in N2a and HT22 cells in a time-dependent manner. Circ_0000115 silencing attenuated OGD-induced apoptosis, oxidative stress and inflammation in N2a and HT22 cells. Mechanistically, circ_0000115 directly sponged miR-1224-5p, which targeted NOS3. Furthermore, rescue experiments showed that miR-1224-5p overexpression abolished the neuroprotective effect of circ_0000115 in N2a and HT22 cells under OGD treatment. Besides that, silencing of miR-1224-5p protected N2a and HT22 cells against OGD-evoked injury, which was counteracted by NOS3 knockdown. Circ_0000115 protects N2a and HT22 cells against OGD-evoked neuronal apoptosis, inflammation, and oxidative stress via the miR-1224-5p/NOS3 axis, providing an exciting view of the pathogenesis of cerebral ischemia.

The Mechanisms of Long Non-coding RNA-XIST in Ischemic Stroke: Insights into Functional Roles and Therapeutic Potential

Ischemic stroke, which occurs due to the occlusion of cerebral arteries, is a common type of stroke. Recent research has highlighted the important role of long non-coding RNAs (lncRNAs) in the development of cerebrovascular diseases, specifically ischemic stroke. Understanding the functional roles of lncRNAs in ischemic stroke is crucial, given their potential contribution to the disease pathology. One noteworthy lncRNA is X-inactive specific transcript (XIST), which exhibits downregulation during the early stages of ischemic stroke and subsequent upregulation in later stages. XIST exert its influence on the development of ischemic stroke through interactions with multiple miRNAs and transcription factors. These interactions play a significant role in the pathogenesis of the condition. In this review, we have provided a comprehensive summary of the functional roles of XIST in ischemic stroke. By investigating the involvement of XIST in the disease process, we aim to enhance our understanding of the mechanisms underlying ischemic stroke and potentially identify novel therapeutic targets.

Penumbra-targeted CircOGDH siRNA-loaded nanoparticles alleviate neuronal apoptosis in focal brain ischaemia

BACKGROUND

Nanoparticles (NPs) are a class of substances that can be loaded with therapeutic agents delivered to specific areas. In our earlier research, we identified a neuron-derived circular RNA (circRNA), circular oxoglutarate dehydrogenase (CircOGDH), as a promising therapeutic target for acute ischaemic stroke. This study dedicated to explore a prospective preliminary strategy of CircOGDH-based NP delivered to the ischaemic penumbra region in middle cerebral artery occlusion/reperfusion (MCAO/R) mice.

METHODS

Immunofluorescence in primary cortex neurons and in vivo fluorescence imaging revealed endocytosis of Poly(lactide-co-glycolide) (PLGA) poly amidoamine(PAMAM)@CircOGDH small interfering RNA (siRNA) NPs. Western blotting analysis and CCK8 assay were performed to evaluate the apoptotic level in ischaemic neurons treated with PLGA-PAMAM@CircOGDH siRNA NPs. Quantitative reverse transcription PCR experiments, mice behaviour test, T2 MRI analysis, Nissl and TdT-mediated dUTP nick end labeling (TUNEL) co-staining were performed to evaluate the apoptosis level of ischaemic penumbra neurons in MCAO/R mice. Biosafety evaluation of NPs in MCAO/R mice was detected by blood routine examination, liver and kidney function examination and HE staining.

RESULTS

PLGA-PAMAM@CircOGDH siRNA NPs were successfully assembled. Endocytosis of PLGA-PAMAM@CircOGDH siRNA NPs in ischaemic neurons alleviated neuronal apoptotic level in vitro and in vivo. Furthermore, mice behaviour test showed that the neurological defects of MCAO/R mice were significantly alleviated after the tail injection of PLGA-PAMAM@CircOGDH siRNA NPs, and no toxic effects were observed.

CONCLUSION

In conclusion, our results suggest that PLGA-PAMAM@CircOGDH siRNA NPs can be delivered to the ischaemic penumbra region and alleviate neuron apoptosis in MCAO/R mice and in ischaemic neurons; therefore, our study provides a desirable approach for using circRNA-based NPs for the treatment of ischaemic stroke.

Analysis of the expression level and predictive value of CLEC16A|miR-654-5p|RARA regulatory axis in the peripheral blood of patients with ischemic stroke based on biosignature analysis

Introduction

Ischemic stroke (IS) is a cerebrovascular disease that can be disabling and fatal, and there are limitations in the clinical treatment and prognosis of IS. It has been reported that changes in the expression profile of circRNAs have been found during injury in ischemic stroke, and circRNAs play an important role in the IS cascade response. However, the specific mechanisms involved in the pathogenesis of IS are not yet fully understood, and thus in-depth studies are needed.

Methods

In this study, one circRNA dataset (GSE161913), one miRNA dataset (GSE60319) and one mRNA dataset (GSE180470) were retrieved from the Gene Expression Omnibus (GEO) database and included, and the datasets were differentially expressed analyzed by GEO2R and easyGEO to get the DEcircRNA, DEmiRNA and DEmRNA, and DEmRNA was enriched using ImageGP, binding sites were predicted in the ENCORI database, respectively, and the competitive endogenous RNA (ceRNA) regulatory network was visualized by the cytoscape software, and then selected by MCC scoring in the cytoHubba plugin Hub genes. In addition, this study conducted a case-control study in which blood samples were collected from stroke patients and healthy medical examiners to validate the core network of ceRNAs constructed by biosignature analysis by real-time fluorescence quantitative qRT-PCR experiments.

Results

A total of 233 DEcircRNAs, 132 DEmiRNAs and 72 DEmRNAs were screened by bioinformatics analysis. circRNA-mediated ceRNA regulatory network was constructed, including 148 circRNAs, 43 miRNAs and 44 mRNAs. Finally, CLEC16A|miR-654-5p|RARA competitive endogenous regulatory axis was selected for validation by qRT-PCR, and the validation results were consistent with the bioinformatics analysis.

Discussion

In conclusion, the present study establishes a new axis of regulation associated with IS, providing new insights into the pathogenesis of IS.

Progesterone improved the behavior of PC12 cells under OGD/R by reducing FABP5 expression and inhibiting TLR4/NF-κB signaling pathway

Herein, PC12 cells were applied to detect the impact of progesterone under oxygen glucose deprivation/reperfusion (OGD/R) stimulation. The cell proliferation of PC12 cells was evaluated by cell counting kit-8 assay, and the concentrations of MDA, ROS and SOD were examined by their corresponding Enzyme Linked Immunosorbent Assay kits. The invasion and migration properties of PC12 cells were evaluated by transwell and wound healing assays, respectively. The expression patterns of related genes were evaluated by western blot and qPCR. Under OGD/R stimulation, progesterone treatment could elevate the viability of PC12 cells, reduce the levels of MDA and ROS, and elevate the concentration of SOD. Moreover, progesterone treatment could strengthen the invasion and migration abilities of PC12 cells under OGD/R condition, as well as decrease the apoptosis and inflammation. FABP5 expression was significantly increased in PC12 cells under OGD/R stimulation, which was reversed after progesterone stimulation. Under OGD/R stimulation, the protective effects of progesterone on PC12 cells were strengthened after si-FABP5 treatment. The protein levels of TLR4, p-P65 NF-κB, and P65 NF-κB in OGD/R-induced PC12 cells were increased, which were inhibited after progesterone treatment. Progesterone exerted protective effects on PC12 cells by targeting FABP5 under OGD/R stimulation.

Inflammatory Factor IL1α Induces Aberrant Astrocyte Proliferation in Spinal Cord Injury Through the Grin2c/Ca2+/CaMK2b Pathway

Spinal cord injury (SCI) is one of the most devastating traumas, and the aberrant proliferation of astrocytes usually causes neurological deficits. However, the mechanism underlying astrocyte over-proliferation after SCI is unclear. Grin2c (glutamate ionotropic receptor type 2c) plays an essential role in cell proliferation. Our bioinformatic analysis indicated that Grin2c and Ca2+ transport functions were inhibited in astrocytes after SCI. Suppression of Grin2c stimulated astrocyte proliferation by inhibiting the Ca2+/calmodulin-dependent protein kinase 2b (CaMK2b) pathway in vitro. By screening different inflammatory factors, interleukin 1α (IL1α) was further found to inhibit Grin2c/Ca2+/CaMK2b and enhance astrocyte proliferation in an oxidative damage model. Blockade of IL1α using neutralizing antibody resulted in increased Grin2c expression and the inhibition of astrocyte proliferation post-SCI. Overall, this study suggests that IL1α promotes astrocyte proliferation by suppressing the Grin2c/Ca2+/CaMK2b pathway after SCI, revealing a novel pathological mechanism of astrocyte proliferation, and may provide potential targets for SCI repair.

Circular RNA PTP4A2 regulates microglial polarization through STAT3 to promote neuroinflammation in ischemic stroke

OBJECTIVE

Microglial polarization plays a critical role in neuroinflammation and may be a potential therapeutic target for ischemic stroke. This study was to explore the role and underlying molecular mechanism of Circular RNA PTP4A2 (circPTP4A2) in microglial polarization after ischemic stroke.

METHODS

C57BL/6J mice underwent transient middle cerebral artery occlusion (tMCAO), while primary mouse microglia and BV2 microglial cells experienced oxygen glucose deprivation/reperfusion (OGD/R) to mimic ischemic conditions. CircPTP4A2 shRNA lentivirus and Colivelin were used to knock down circPTP4A2 and upregulate signal transducer and activator of transcription 3 (STAT3) phosphorylation, respectively. Microglial polarization was assessed using immunofluorescence staining and Western blot. RNA pull-down and RNA binding protein immunoprecipitation (RIP) were applied to detect the binding between circPTP4A2 and STAT3.

RESULTS

The levels of circPTP4A2 were significantly increased in plasma and peri-infarct cortex in tMCAO mice. CircPTP4A2 knockdown reduced infarct volume, increased cortical cerebral blood flow (CBF), and attenuated neurological deficits. It also decreased pro-inflammatory factors levels in peri-infarct cortex and plasma, and increased anti-inflammatory factors concentrations 24 h post-stroke. In addition, circPTP4A2 knockdown suppressed M1 microglial polarization and promoted M2 microglial polarization in both tMCAO mice and OGD/R-induced BV2 microglial cells. Moreover, circPTP4A2 knockdown inhibited the phosphorylation of STAT3 induced by oxygen-glucose deprivation. In contrast, increased phosphorylation of STAT3 partly counteracted the effects of circPTP4A2 knockdown. RNA pull-down and RIP assays further certified the binding between circPTP4A2 and STAT3.

CONCLUSION

These results revealed regulatory mechanisms of circPTP4A2 that stimulated neuroinflammation by driving STAT3-dependent microglial polarization in ischemic brain injury. CircPTP4A2 knockdown reduced cerebral ischemic injury and promoted microglial M2 polarization, which could be a novel therapeutic target for ischemic stroke.

Inhibition of OGFOD1 by FG4592 confers neuroprotection by activating unfolded protein response and autophagy after ischemic stroke

BACKGROUND

Acute ischemic stroke is a common neurological disease with a significant financial burden but lacks effective drugs. Hypoxia-inducible factor (HIF) and prolyl hydroxylases (PHDs) participate in the pathophysiological process of ischemia. However, whether FG4592, the first clinically approved PHDs inhibitor, can alleviate ischemic brain injury remains unclear.

METHODS

The infarct volumes and behaviour tests were first analyzed in mice after ischemic stroke with systemic administration of FG4592. The knockdown of HIF-1α and pretreatments of HIF-1/2α inhibitors were then used to verify whether the neuroprotection of FG4592 is HIF-dependent. The targets predicting and molecular docking methods were applied to find other targets of FG4592. Molecular, cell biological and gene knockdown methods were finally conducted to explore the potential neuroprotective mechanisms of FG4592.

RESULTS

We found that the systemic administration of FG4592 decreased infarct volume and improved neurological defects of mice after transient or permanent ischemia. Meanwhile, FG4592 also activated autophagy and inhibited apoptosis in peri-infarct tissue of mice brains. However, in vitro and in vivo results suggested that the neuroprotection of FG4592 was not classical HIF-dependent. 2-oxoglutarate and iron-dependent oxygenase domain-containing protein 1 (OGFOD1) was found to be a novel target of FG4592 and regulated the Pro-62 hydroxylation in the small ribosomal protein s23 (Rps23) with the help of target predicting and molecular docking methods. Subsequently, the knockdown of OGFOD1 protected the cell against ischemia/reperfusion injury and activated unfolded protein response (UPR) and autophagy. Moreover, FG4592 was also found to activate UPR and autophagic flux in HIF-1α independent manner. Blocking UPR attenuated the neuroprotection, pro-autophagy effect and anti-apoptosis ability of FG4592.

CONCLUSION

This study demonstrated that FG4592 could be a candidate drug for treating ischemic stroke. The neuroprotection of FG4592 might be mediated by inhibiting alternative target OGFOD1, which activated the UPR and autophagy and inhibited apoptosis after ischemic injury. The inhibition of OGFOD1 is a novel therapy for ischemic stroke.

CircRNA and Stroke: New Insight of Potential Biomarkers and Therapeutic Targets

Stroke, the second-largest cause of death and the leading cause of disability globally, presents significant challenges in terms of prognosis and treatment. Identifying reliable prognosis biomarkers and treatment targets is crucial to address these challenges. Circular RNA (circRNA) has emerged as a promising research biomarkers and therapeutic targets because of its tissue specificity and conservation. However, the potential role of circRNA in stroke prognosis and treatment remains largely unexplored. This review briefly elucidate the mechanism underlying circRNA's involvement in stroke pathophysiology. Additionally, this review summarizes the impact of circRNA on different forms of strokes, including ischemic stroke and hemorrhagic stroke. And, this article discusses the positive effects of circRNA on promoting cerebrovascular repair and regeneration, maintaining the integrity of the blood-brain barrier (BBB), and reducing neuronal injury and immune inflammatory response. In conclusion, the significance of circRNA as a potential prognostic biomarker and a viable therapeutic target was underscored.

CircRNAs in Alzheimer's disease: What are the prospects?

Circular RNAs (circRNAs) is a fascinating covalently closed circular non-coding RNA that is abundantly present in the transcriptome of eukaryotic cells. Its versatile nature allows it to participate in a multitude of pathological and physiological processes within the organism. One of its crucial functions is acting as a microRNA sponge, modulating protein transcription levels, and forming interactions with essential RNA-binding proteins. Remarkably, circRNAs demonstrates a specific enrichment in various vital areas of the brain, including the cortex, hippocampus, white matter, and photoreceptor neurons, particularly in aging organisms. This intriguing characteristic has led scientists to explore its potential as a significant biological marker of neurodegeneration, offering promising insights into neurodegenerative diseases like Alzheimer's disease (AD). In AD, there has been an interesting observation of elevated levels of circRNAs in both peripheral blood and synaptic terminals of affected individuals. This intriguing finding raises the possibility that circRNAs may have a central role in the initiation and progression of AD. Notably, different categories of circRNAs, including HDAC9, HOMER1, Cwc27, Tulp4, and PTK2, have been implicated in driving the pathological changes associated with AD through diverse mechanisms. For instance, these circRNAs have been demonstrated to contribute to the accumulation of beta-amyloid, which is a hallmark characteristic of AD. Additionally, these circRNAs contribute to the excessive phosphorylation of tau protein, a phenomenon associated with neurofibrillary tangles, further exacerbating the disease. Moreover, they are involved in aggravating neuroinflammation, which is known to play a critical role in AD's pathogenesis. Lastly, these circRNAs can cause mitochondrial dysfunction, disrupting cellular energy production and leading to cognitive impairment. As researchers delve deeper into the intricate workings of circRNAs, they hope to unlock its full potential as a diagnostic tool and therapeutic target for neurodegenerative disorders, paving the way for innovative treatments and better management of such devastating conditions.

Discovery of Highly Selective PARP7 Inhibitors with a Novel Scaffold for Cancer Immunotherapy

PARP7 plays a crucial role in cancer immunity. The inhibition of PARP7 has shown potential in boosting the immune response against cancer, making it an attractive target for cancer immunotherapy. Herein, we employed a rigid constraint strategy (reduction in molecular flexibility) to design and synthesize a series of novel indazole-7-carboxamide derivatives based on the structure of RBN-2397. Among these derivatives, (S)-XY-05 was identified as the most promising PARP7 inhibitor (IC50: 4.5 nM). Additionally, (S)-XY-05 showed enhanced selectivity toward PARP7 and improved pharmacokinetic properties (oral bioavailability: 94.60%) compared with RBN-2397 (oral bioavailability: 25.67%). In the CT26 syngeneic mouse model, monotherapy with (S)-XY-05 displayed a strong antitumor effect (TGI: 83%) by activating T-cell-mediated immunity within the tumor microenvironment. Collectively, we confirmed that (S)-XY-05 has profound effects on tumor immunity, which paves the way for future studies of PARP7 inhibitors that could be utilized in cancer immunotherapy.