Sevoflurane attenuates cardiomyocyte apoptosis by mediating the miR-219a/AIM2/TLR4/MyD88 axis in myocardial ischemia/reperfusion injury in mice

The cytoplasmic sensor, the AIM2 inflammasome: A precise therapeutic target in vascular and metabolic diseases

Cardio-cerebrovascular diseases encompass pathological changes in the heart, brain and vascular system, which pose a great threat to health and well-being worldwide. Moreover, metabolic diseases contribute to and exacerbate the impact of vascular diseases. Inflammation is a complex process that protects against noxious stimuli but is also dysregulated in numerous so-called inflammatory diseases, one of which is atherosclerosis. Inflammation involves multiple organ systems and a complex cascade of molecular and cellular events. Numerous studies have shown that inflammation plays a vital role in cardio-cerebrovascular diseases and metabolic diseases. The absent in melanoma 2 (AIM2) inflammasome detects and is subsequently activated by double-stranded DNA in damaged cells and pathogens. With the assistance of the mature effector molecule caspase-1, the AIM2 inflammasome performs crucial biological functions that underpin its involvement in cardio-cerebrovascular diseases and related metabolic diseases: The production of interleukin-1 beta (IL-1β), interleukin-18 (IL-18) and N-terminal pore-forming Gasdermin D fragment (GSDMD-N) mediates a series of inflammatory responses and programmed cell death (pyroptosis and PANoptosis). Currently, several agents have been reported to inhibit the activity of the AIM2 inflammasome and have the potential to be evaluated for use in clinical settings. In this review, we systemically elucidate the assembly, biological functions, regulation and mechanisms of the AIM2 inflammasome in cardio-cerebrovascular diseases and related metabolic diseases and outline the inhibitory agents of the AIM2 inflammasome as potential therapeutic drugs.

MicroRNA-specific therapeutic targets and biomarkers of apoptosis following myocardial ischemia-reperfusion injury

MicroRNAs are single-stranded non-coding RNAs that participate in post-transcriptional regulation of gene expression, it is involved in the regulation of apoptosis after myocardial ischemia-reperfusion injury. For example, the alteration of mitochondrial structure is facilitated by MicroRNA-1 through the regulation of apoptosis-related proteins, such as Bax and Bcl-2, thereby mitigating cardiomyocyte apoptosis. MicroRNA-21 not only modulates the expression of NF-κB to suppress inflammatory signals but also activates the PI3K/AKT pathway to mitigate ischemia-reperfusion injury. Overexpression of MicroRNA-133 attenuates reactive oxygen species (ROS) production and suppressed the oxidative stress response, thereby mitigating cellular apoptosis. MicroRNA-139 modulates the extrinsic death signal of Fas, while MicroRNA-145 regulates endoplasmic reticulum calcium overload, both of which exert regulatory effects on cardiomyocyte apoptosis. Therefore, the article categorizes the molecular mechanisms based on the three classical pathways and multiple signaling pathways of apoptosis. It summarizes the targets and pathways of MicroRNA therapy for ischemia-reperfusion injury and analyzes future research directions.

Sevoflurane Preconditioning Downregulates GRIA1 Expression to Attenuate Cerebral Ischemia-Reperfusion-Induced Neuronal Injury

Cerebral ischemia/reperfusion (I/R) injury is the main cause of death following trauma. The neuroprotective effect of sevoflurane (Sev) has been implicated in cerebral I/R injury. However, the mechanisms remain elusive. In this study, we aimed to explore its function in PC12 exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) and in rats challenged with I/R. Sev pretreatment reduced the damage of PC12 cells after OGD/R treatment. Moreover, Sev pretreatment ameliorated neurobehavioral deficits induced by I/R treatment, reduced brain infarct volume, and decreased apoptosis of neurons in hippocampal tissues. Sev pretreatment reduced the surface expression of glutamate receptor 1 (GRIA1) in neurons, while GRIA1 reduced the neuroprotective effects of Sev pretreatment in vitro and in vivo. There was no difference in the surface expression of GRIA2 in rats with I/R and PC12 cells exposed to OGD/R. The ratio of GRIA1/GRIA2 surface expression was reduced, and calcium permeable-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (CP-AMPAR) was blocked by Sev. Together, Sev might exert beneficial effects on cerebral I/R-induced neuronal injury through inhibiting the surface expression of GRIA1 and blocking CP-AMPAR.

The AIM2 inflammasome: A novel biomarker and target in cardiovascular disease

Absent in melanoma 2 (AIM2) is a cytoplasmic sensor that recognises the double-strand DNA. AIM2 inflammasome is a protein platform in the cell that initiates innate immune responses by cleaving pro-caspase-1 and converting IL-1β and IL-18 to their mature forms. Additionally, AIM2 inflammasome promotes pyroptosis by converting Gasdermin-D (GSDMD) to GSDMD-N fragments. An increasing number of studies have indicated the important and decisive roles of the AIM2 inflammasome, IL-1β, and pyroptosis in cardiovascular diseases, such as coronary atherosclerosis, myocardial infarction, ischaemia/reperfusion injury, heart failure, aortic aneurysm and ischaemic stroke. Here, we review the molecular mechanism of the activation and effect of the AIM2 inflammasome in cardiovascular disease, revealing new insights into pathogenic factors that may be targeted to treat cardiovascular disease and related dysfunctions.

Effects of penehyclidine hydrochloride on myocardial ischaemia-reperfusion injury in rats by inhibiting TLR4/MyD88/NF-κB pathway via miR-199a-3p

This study was to probe the role of penehyclidine hydrochloride (PHC) mediating the impact of toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-kappa B (NF-κB) signalling pathway on myocardial ischaemia-reperfusion injury (MI/RI) in rats through miR-199a-3p. The rat MI/RI model was established through ligating left anterior descending (LAD) coronary artery. PHC was injected preoperatively into the model rats, and injected with miR-199a-3p lentiviral vector or TLR4 antagonist (TAK-242). Next, cardiac function of rats was examined by echocardiography, and rat serum indicators, oxidative stress levels and inflammatory factors were detected. HE staining was applied to detect pathological tissue structure, TUNEL staining to detect apoptosis rate, qRCR and western blot to detect miR-199a-3p and TLR4/MyD88/NF-κB expressions in rat myocardial tissues. Dual luciferase reporter experiment was conducted to confirm the relationship between miR-199a-3p and TLR4. In conclusion, PHC suppresses TLR4/MyD88/NF-κB signalling pathway through miR-199a-3p, thereby improving MI/RI in rats.

Ibuprofen Alleviates Acute Pancreatitis- (AP-) Induced Myocardial Injury by Inhibiting AIM2

Objective

The lack of certain trace elements such as selenium, molybdenum, magnesium or related nutrients in the soil, water quality and food in the disease area, which caused disturbance of myocardium metabolism and resulted in injury and necrosis. The aim of the study was to explore the mechanism of ibuprofen alleviating myocardial injury caused by acute pancreatitis (AP).

Method

We have established AP cell model and rat model. HE staining is used for histological examination. ELISA is used to determine the levels of proinflammatory cytokines (TNF-α and IL-6) and markers of myocardial injury (LDH and CK-MB). qRT-PCR and Western blot are used to analyze the mRNA and protein levels of related genes.

Results

The expression level of AIM2 was significantly increased in AP cells; downregulation of AIM2 alleviated inflammation and myocardial injury induced by AP cells; ibuprofen could inhibit the expression of AIM2 and alleviate inflammation and myocardial injury induced by AP cells. In vivo experiments have found that ibuprofen can inhibit the expression of AIM2 to alleviate myocardial injury in AP rat.

Conclusion

Ibuprofen can alleviate myocardial injury caused by acute pancreatitis by inhibiting the expression of AIM2.

Mesenchymal Stem Cell Exosomal miR-146a Mediates the Regulation of the TLR4/MyD88/NF-κB Signaling Pathway in Inflammation due to Diabetic Retinopathy

Diabetic retinopathy (DR) is the main cause of vision loss in diabetic patients, which cannot be completely resolved by typical blood sugar control. Inflammation influences the development of DR, so reducing the inflammatory response in DR patients is crucial to the prevention of DR. Therefore, we explored the regulatory effect of bone marrow mesenchymal stem cell (BMSC) exosomes on inflammation in DR mice. In order to analyze the mechanism of action, we used BMSC exosomal miR-146a to treat microglias in DR mice to observe cellular changes and expression of inflammatory factors. It was found that BMSC exosomal miR-146a reduced the levels of proliferating cell antigen and B-cell lymphoma-2 in microglias of DR mice and increased Bcl-2-related X with cysteine aspartic protease-3. By analyzing the expression of inflammatory factors, we found that BMSC exosomal miR-146a reduced the levels of TNF-α, IL-1β, and IL-6, which suggested that miR-146a can alleviate inflammation in DR mice. Further exploration found that miR-146a reduced the activity of TLR4 and increased the activity of MyD88 and NF-κB. Furthermore, the overexpression of TLR4 reversed the effects of miR-146a on the proliferation, apoptosis, and inflammation of microglias. Our study demonstrated that BMSC exosomal miR-146a can regulate the inflammatory response of DR by mediating the TLR4/MyD88/NF-κB pathway, providing an experimental basis for the prevention and treatment of DR.

The Association of Serum AIM2 Level with the Prediction and Short-Term Prognosis of Coronary Artery Disease

Objective. Coronary artery disease (CAD), one of the commonest cardiovascular diseases, has high morbidity and mortality. Absent in melanoma 2 (AIM2) is involved in atherosclerosis, and no clinical trials have explored the association between AIM2 and CAD. Therefore, this study was aimed at evaluating the predictive and short-term prognostic value of AIM2 for CAD. Methods. 279 patients who underwent coronary angiography were enrolled in this study. The AIM2 level was detected from the serum of collected artery blood samples. The association of serum AIM2 level with the prediction and short-term prognosis of CAD was further assessed. Results. The serum AIM2 level of the CAD group was significantly higher than the control group ( $5.5\pm 2.1$ vs. $3.7\pm 1.7$ ; $p<0.001$ ). AIM2 was demonstrated to be the risk factor of CAD [odds ratio, 1.589; 95% confidence interval (CI), 1.346-1.876; $p<0.001$ ]. The area under the receiver operating characteristic (ROC) curve of 0.738 showed the diagnostic value of AIM2 in CAD. Additionally, AIM2 was an independent predictor of major adverse cardiovascular events (hazard ratio, 1.453; 95% CI, 1.086-1.945; $p=0.012$ ), and CAD patients with high AIM2 levels (>4.9 ng/mL) had a markedly lower survival rate (log-rank $p=0.040$ ). Conclusions. The serum AIM2 $\text{level}>4.9$  ng/mL can predict CAD to a certain extent. AIM2 might be an independent predictor of its short-term poor prognosis.

Emerging Roles of Inflammasomes in Cardiovascular Diseases

Cardiovascular diseases are known as the leading cause of morbidity and mortality worldwide. As an innate immune signaling complex, inflammasomes can be activated by various cardiovascular risk factors and regulate the activation of caspase-1 and the production and secretion of proinflammatory cytokines such as IL-1β and IL-18. Accumulating evidence supports that inflammasomes play a pivotal role in the progression of atherosclerosis, myocardial infarction, and heart failure. The best-known inflammasomes are NLRP1, NLRP3, NLRC4, and AIM2 inflammasomes, among which NLRP3 inflammasome is the most widely studied in the immune response and disease development. This review focuses on the activation and regulation mechanism of inflammasomes, the role of inflammasomes in cardiovascular diseases, and the research progress of targeting NLRP3 inflammasome and IL-1β for related disease intervention.

Maslinic Acid Attenuates Ischemia/Reperfusion Injury-Induced Myocardial Inflammation and Apoptosis by Regulating HMGB1-TLR4 Axis

Aims: The inflammatory response and apoptosis are the major pathological features of myocardial ischemia/reperfusion injury (MI/RI). Maslinic acid (MA), a natural pentacyclic triterpene with various bioactivities, plays critical roles in the multiple cellular biological processes, but its protective effects on the pathophysiological processes of MI/RI have not been extensively investigated. Our study aimed to determine whether MA treatment alleviate ischemia/reperfusion (I/R)-induced myocardial inflammation and apoptosis both in vitro and in vivo, and further reveal the underlying mechanisms. Methods and results: An MI/RI rat model was successfully established by ligating the left anterior descending coronary artery and H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to mimic I/R injury. In addition, prior to H/R stimulation or myocardial I/R operation, the H9c2 cells or rats were treated with varying concentrations of MA or vehicle for 24 h and two consecutive days, respectively. In this study, our results showed that MA could obviously increase the cell viability and decrease the cardiac enzymes release after H/R in vitro. MA could significantly improve the H/R-induced cardiomyocyte injury and I/R-induced myocardial injury in a dose-dependent manner. Moreover, MA suppressed the expression of inflammatory cytokines (tumor necrosis factor alpha [TNF-α, interleukin-1β [IL-1β and interleukin-6 [IL-6]) and the expressions of apoptosis-related proteins (cleaved caspase-3 and Bax) as well as increased the levels of anti-apoptotic protein Bcl-2 expression both in vitro and in vivo. Mechanistically, MA significantly inhibited nuclear translocation of nuclear factor-κB (NF-κB) p65 after H/R via regulating high mobility group box 1 (HMGB1)/toll-like receptor 4 (TLR4) axis. Conclusion: Taken together, MA treatment may alleviate MI/RI by suppressing both the inflammation and apoptosis in a dose-dependent manner, and the cardioprotective effect of MA may be partly attributable to the inactivation of HMGB1/TLR4/NF-κB pathway, which offers a new therapeutic strategy for MI/RI.