ALDH2 Overexpression Alleviates High Glucose-Induced Cardiotoxicity by Inhibiting NLRP3 Inflammasome Activation

DSCR1-1 attenuates osteoarthritis-associated chondrocyte injury by regulating the CREB1/ALDH2/Wnt/β-catenin axis: An in vitro and in vivo study

The progression of osteoarthritis (OA) includes the initial inflammation, subsequent degradation of the extracellular matrix (ECM), and chondrocyte apoptosis. Down syndrome candidate region 1 (DSCR1) is a stress-responsive gene and expresses in varied types of cells, including chondrocytes. Bioinformatics analysis of GSE103416 and GSE104739 datasets showed higher DSCR1 expression in the inflamed cartilage tissues and chondrocytes of OA. DSCR1 had two major isoforms, isoform 1 (DSCR1-1) and isoform 4 (DSCR1-4). We found that DSCR1-1 had a faster (in vitro) and higher expression (in vivo) response to OA compared to DSCR1-4. IL-1β-induced apoptosis, inflammation, and ECM degradation in chondrocytes were attenuated by DSCR1-1 overexpression. DSCR1-1 triggered the phosphorylation of cAMP response element-binding 1 (CREB1) at 133 serine sites by decreasing calcineurin activity. Moreover, activated CREB1 moved into the cell nucleus and combined in the promoter regions of aldehyde dehydrogenase 2 (ALDH2), thus enhancing its gene transcription. ALDH2 could recover Wnt/β-catenin signaling transduction by enhancing phosphorylation of β-catenin at 33/37 serine sites and inhibiting the migration of β-catenin protein from the cellular matrix to the nucleus. In vivo, adenoviruses (1 × 108 PFU) overexpressing DSCR1-1 were injected into the articular cavity of C57BL/6 mice with medial meniscus surgery-induced OA, and it showed that DSCR1-1 overexpression ameliorated cartilage injury. Collectively, our study demonstrates that DSCR1-1 may be a potential therapeutic target of OA.

The mechanism and promising therapeutic strategy of diabetic cardiomyopathy dysfunctions: Focus on pyroptosis

Diabetes is a major risk factor for cardiovascular diseases, and myocardial damage caused by hyperglycemia is the main cause of heart failure. However, there is still a lack of systematic understanding of myocardial damage caused by diabetes. At present, we believe that the cellular inflammatory damage caused by hyperglycemia is one of the causes of diabetic cardiomyopathy. Pyroptosis, as a proinflammatory form of cell death, is closely related to the occurrence and development of diabetic cardiomyopathy. Therefore, this paper focuses on the important role of inflammation in the occurrence and development of diabetic cardiomyopathy. From the perspective of pyroptosis, we summarize the pyroptosis of different types of cells in diabetic cardiomyopathy and its related signaling pathways. It also summarizes the treatment of diabetic cardiomyopathy, hoping to provide methods for the prevention and treatment of diabetic cardiomyopathy by inhibiting pyroptosis.

Effect of NLRP3 gene knockdown on pyroptosis and ferroptosis in diabetic cardiomyopathy injury

Diabetic cardiomyopathy (DCM) is a chronic disease caused by diabetes mellitus, which is recognized as a worldwide challenging disease. This study aimed to investigate the role and the potential mechanism of knocking down the NACHT-, LRR- and PYD domains-containing protein 3 (NLRP3), an inflammasome associated with onset and progression of various diseases, on high glucose or diabetes -induced cardiac cells pyroptosis and ferroptosis, two regulated non-necrosis cell death modalities discovered recent years. In the present study, both in vivo and in vitro studies were conducted simultaneously. Diabetic rats were induced by 55 mg/kg intraperitoneal injection of streptozotocin (STZ). Following the intraperitoneal injection of MCC950 (10 mg/kg), On the other hand, the DCM model in H9C2 cardiac cells was simulated with 35 mmol/L glucose and a short hairpin RNA vector of NLRP3 were transfected to cells. The results showed that in vivo study, myocardial fibers were loosely arranged and showed inflammatory cell infiltration, mitochondrial cristae were broken and the GSDMD-NT expression was found notably increased in the DM group, while the protein expressions of xCT and GPX4 was significantly decreased, both of which were reversed by MCC950. High glucose reduced the cell viability and ATP level in vitro, accompanied by an increase in LDH release. All of the above indicators were reversed after NLRP3 knockdown compared with the HG treated alone. Moreover, the protein expressions of pyroptosis- and ferroptosis-related fators were significantly decreased or increased, consistent with the results shown by immunofluorescence. Furthermore, the protective effects of NLRP3 knockdown against HG were reversed following the mtROS agonist rotenone (ROT) treatment. In conclusion, inhibition of NLRP3 suppressed DM-induced myocardial injury. Promotion of mitochondrial ROS abolished the protective effect of knockdown NLRP3, and induced the happening of pyroptosis and ferroptosis. These findings may present a novel therapeutic underlying mechanism for clinical diabetes-induced myocardial injury treatment.

IRE1α regulates macrophage polarization in type 2 diabetic periodontitis through promoting endoplasmic reticulum stress

OBJECTIVES

The aim of this study was to investigate the effect of 4μ8c, an inhibitor targeting the endoplasmic reticulum stress-associated factor IRE1α, on macrophage polarization in an experimental model of diabetic periodontitis through ex vivo experiments.

MATERIALS AND METHODS

Local alveolar bone parameters were evaluated using Micro-CT following intraperitoneal administration of 4μ8c in mice with experimental diabetic periodontitis. Surface markers indicating macrophage polarization were identified using immunofluorescence. In vitro experiments were performed employing bone marrow-derived macrophages and gingival fibroblasts. Macrophage polarization was determined using flow cytometry. Principal impacted signaling pathways were identified through Western blot analysis.

RESULTS

Results from both in vitro and in vivo experiments demonstrated that 4μ8c mitigated alveolar bone resorption and inflammation in mice with diabetic periodontitis. Furthermore, it modulated macrophage polarization towards the M2 phenotype and augmented M2 macrophage polarization through the MAPK signaling pathway.

CONCLUSIONS

These findings suggest that inhibiting IRE1α can modulate macrophage polarization and alleviate ligature-induced diabetic periodontitis via the MAPK signaling pathway. This unveils a novel mechanism, offering a scientific foundation for the treatment of experimental diabetic periodontitis.

Ethanol causes non-communicable disease through activation of NLRP3 inflammasome: a review on mechanism of action and potential interventions

Background: Ethanol exposure has been suggested to be implicated in the initiation and progression of several non-communicable diseases (NCD), including neurological disorders, diabetes mellitus, alcoholic liver disease, gastric injury, pancreatitis, and atherosclerosis. Recent findings show that the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome is involved in the progression of ethanol-induced NCDs.Objective: The aim of this review was to summarize the research progress on NCDs associated with the action of the NLRP3 inflammasome by ethanol and potential interventions, with a specific focus on preclinical literature.Methods: A literature search was conducted on PubMed using the keywords "[ethanol] and [NLRP3]" up until January 2023. Articles describing cases of NCDs caused by ethanol and associated with the NLRP3 inflammasome were included.Results: After removing duplicates, 35 articles were included in this review. These studies, mostly conducted in animals or in vitro, provide evidence that ethanol can contribute to the development of NCDs, such as neurological disorders, alcoholic liver disease, gastric injury, pancreatitis, and atherosclerosis, by activating the NLRP3 inflammasome. Ethanol exposure primarily triggers NLRP3 inflammasome activation by influencing the TRL/NF-κB, ROS-TXNIP-NLRP3 and P2X7 receptor (P2X7R) signaling pathways. Several natural extracts and compounds have been found to alleviate NCDs caused by ethanol consumption by inhibiting the activation of the NLRP3 inflammasome.Conclusion: Preclinical research supports a role for ethanol-induced NLRP3 inflammasome in the development of NCDs. However, the clinical relevance remains uncertain in the relative absence of clinical studies.

[Spermidine alleviates lipopolysaccharide-induced myocardial injury in mice by suppressing apoptosis, ROS production and ferroptosis]

OBJECTIVE

To investigate the protective effect of spermidine against lipopolysaccharide (LPS)-induced myocardial injury in mice and the underlying mechanism.

METHODS

C57BL/6 mice subjected to intraperitoneal LPS injection with or without pretreatment with daily gavage of spermidine for 2 weeks were examined for myocardial pathologies using HE staining and transmission electron microscopy. In the cell experiment, cultured rat cardiomyocytes (H9c2 cells) were pretreated with 10 or 20 μmol/L spermidine before LPS exposure for 2 h, and the changes in cell viability and levels of lactate dehydrogenase (LDH) and cardiac troponin Ⅰ (cTNI) were assessed using CCK-8 kit, LDH detection kit and ELISA, respectively. Western blotting was performed to detect the changes in the expressions of Bax, Bcl-2, cleaved caspase-3, SLC7A11 and GPX4; the changes in reactive oxygen species (ROS) and Fe2+ levels were detected using fluorescent probes, and mitochondrial membrane potential of the cells was measured using JC-1 staining.

RESULTS

Treatment of the mice with LPS induced obvious myocardial and mitochondrial damages, which were significantly alleviated by pretreatment with spermidine. In H9c2 cells, LPS exposure significantly lowered the cell viability, increased LDH and cTNI levels and expressions of Bax and cleaved caspase-3 levels, decreased expressions of Bcl-2, SLC7A11 and GPX4, increased ROS production and Fe2+ level (P < 0.05), and lowered mitochondrial membrane potential (all P < 0.05). These effects were significantly alleviated by SPD pretreatment of the cells prior to LPS exposure.

CONCLUSION

Spermidine alleviates LPS-induced myocardial injury by suppressing cell apoptosis and inhibiting cellular ROS production and ferroptosis.

Hsa_circ_0008833 promotes COPD progression via inducing pyroptosis in bronchial epithelial cells

Purpose: Chronic obstructive pulmonary disease (COPD) is a common respiratory disorder. Pyroptosis represents a distinctive form of inflammatory cell death that is mediated through the activation of Caspase-1 and inflammasomes. CircRNAs have emerged as a novel class of biomolecules with implications in various human diseases. This study aims to investigate the circRNAs profile of in COPD progression and identify pivotal circRNAs associated with the development of this disease. Methods: he expression profiles of circRNAs in peripheral blood mononuclear cells of COPD patients were assessed by circRNA microarray. Furthermore, flag-labeled vectors were constructed to assess the potential protein-coding capacity of has-circ-0008833. 16HBE cells were stably transfected with lentivirus approach, and cell proliferation and death were assessed to clarify the functional roles of has-circ-0008833 and its encoded protein circ-0008833aa. Additionally, western blot analysis was furthered performed to determine the level of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD regulated by has-circ-0008833 and circ-0008833-57aa. Results: Initially, we screened the expression profiles of human circRNAs in peripheral blood mononuclear cells of COPD patients, and found that has-circ-0008833 exhibited a significant increase in COPD mononuclear cells. Subsequently, we demonstrated that has-circ-0008833 carried an open reading frame (ORF), which encoded a functional protein, referred to as circ-0008833-57aa. By employing gain-of-function approaches, our results suggested that both circ-0008833 and circ-0008833-57aa inhibited proliferation, but accelerated the rate of 16HBE cell death. Finally, we discovered that circ-0008833 and circ-0008833-57aa promoted the expression of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD in 16HBE cells. Conclusions: Upregulation of circ-0008833 might promote COPD progression by inducing pyroptosis of bronchial epithelial cells through the encoding of a 57-amino acid peptide.

ALDH2 activation attenuates oxygen-glucose deprivation/reoxygenation-induced cell apoptosis, pyroptosis, ferroptosis and autophagy

PURPOSE

It is previously reported that aldehyde dehydrogenase 2 family member (ALDH2) shows neuroprotective effects in cerebral ischemia/reperfusion injury. However, whether the protective effects are through mediating the programmed cell death is yet to be fully elucidated.

METHODS

In vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in HT22 cells and mouse cortical neurons. Subsequently, ALDH2 expression were assessed by qRT-PCR and western blot. The methylation status was examined by methylation-specific PCR (MS-PCR). Then, ALDH2 expression was promoted and suppressed to explore the role of ALDH2 in OGD/R-treated cells. CCK-8 assay was applied to detect cell viability, and flow cytometry was applied to evaluate cell apoptosis. Western blot was applied to detect the apoptosis-related proteins (Caspase 3, Bcl-2 and Bax), necroptosis-related proteins (RIP3 and MLKL), pyroptosis-related proteins (NLRP3 and GSDMD), ferroptosis-related protein (ACSL4 and GPX4), and autophagy-related proteins (LC3B, and p62). IL-1β and IL-18 production was evaluated by ELISA assay. Reactive oxygen species production and Fe2+ content were evaluated by the corresponding detection kit.

RESULTS

In OGD/R-treated cells, ALDH2 expression was decreased, which was due to the hypermethylation of ALDH2 in the promoter region. ALDH2 overexpression improved cell viability and ALDH2 knockdown suppressed cell viability in OGD/R-treated cells. We also found that ALDH2 overexpression attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy, while ALDH2 knockdown facilitated the OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy.

CONCLUSIONS

Collectively, our results implied that ALDH2 attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy to promote cell viability in HT22 cells and mouse cortical neurons.

The role of aldehyde dehydrogenase 2 in cardiovascular disease

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme involved in the detoxification of alcohol-derived acetaldehyde and endogenous aldehydes. The inactivating ALDH2 rs671 polymorphism, present in up to 8% of the global population and in up to 50% of the East Asian population, is associated with increased risk of cardiovascular conditions such as coronary artery disease, alcohol-induced cardiac dysfunction, pulmonary arterial hypertension, heart failure and drug-induced cardiotoxicity. Although numerous studies have attributed an accumulation of aldehydes (secondary to alcohol consumption, ischaemia or elevated oxidative stress) to an increased risk of cardiovascular disease (CVD), this accumulation alone does not explain the emerging protective role of ALDH2 rs671 against ageing-related cardiac dysfunction and the development of aortic aneurysm or dissection. ALDH2 can also modulate risk factors associated with atherosclerosis, such as cholesterol biosynthesis and HDL biogenesis in hepatocytes and foam cell formation and efferocytosis in macrophages, via non-enzymatic pathways. In this Review, we summarize the basic biology and the clinical relevance of the enzymatic and non-enzymatic, tissue-specific roles of ALDH2 in CVD, and discuss the future directions in the research and development of therapeutic strategies targeting ALDH2. A thorough understanding of the complex roles of ALDH2 in CVD will improve the diagnosis, management and prognosis of patients with CVD who harbour the ALDH2 rs671 polymorphism.

Role of sodium pyruvate in maintaining the survival and cytotoxicity of Staphylococcus aureus under high glucose conditions

Glucose is a crucial carbon source for the growth of Staphylococcus aureus, but an excess of glucose is detrimental and even leads to cell death. Pyruvate, the central metabolite of glycolysis, has been shown to have anti-inflammatory and antioxidant properties. This study aimed to investigate the protective effect of pyruvate on S. aureus under high glucose conditions. Sodium pyruvate greatly increased the cytotoxicity of S. aureus strain BAA-1717 to human erythrocytes and neutrophils in vitro. However, the cytotoxicity and survival of S. aureus were significantly reduced by high glucose, which was restored to normal levels by the addition of sodium pyruvate. The expression of hlg and lukS in S. aureus was higher in the LB-GP cultures than that in LB-G cultures, but there was no significant difference in cytotoxicity between LB-GP and LB-G cultures. Furthermore, the hemolytic activity of S. aureus supernatants could be inhibited by the cell-free culture medium (CFCM) of LB-G cultures, suggesting that high levels of extracellular proteases were presence in the CFCM of LB-G cultures, resulting in degradation of the hemolytic factors. The expression of sarA, which negatively regulates extracellular protease secretion, was higher in LB-GP cultures than that in LB-G cultures. Additionally, sodium pyruvate increased acetate production in S. aureus, which helps maintain cell viability under acidic environment. In conclusion, pyruvate plays an important role in the survival and cytotoxicity of S. aureus under high glucose conditions. This finding may aid in the development of effective treatments for diabetic foot infections.

ALDH2 ameliorates ethanol-induced gastric ulcer through suppressing NLPR3 inflammasome activation and ferroptosis

Gastric ulcer (GU) is a prevalent and life-threating gastrointestinal disorder. Aldehyde dehydrogenase 2 (ALDH2) is a pivotal component of alcohol metabolism which has been supported to suppress oxidative stress-elicited DNA damage in gastric mucosa cells. Nonetheless, whether ALDH2 is also involved in GU remains indistinct. Firstly, HCl/ethanol-induced experimental rat GU model was successfully established. RT-qPCR and western blot tested ALDH2 expression in rat tissues. Following the addition of ALDH2 activator Alda-1, gastric lesion area and index were measured. H&E staining detected the histopathology of gastric tissues. ELISA examined the levels of inflammatory mediators. Alcian blue staining evaluated mucus production of gastric mucosa. Oxidative stress levels were estimated by corresponding kits and western blot. Western blot examined the expression of NLRP3 inflammasome- and ferroptosis-related proteins. Prussian blue staining and corresponding assay kits measured ferroptosis. In ethanol-treated GES-1 cells, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, iron content, ferroptosis, inflammation and oxidative stress were detected as aforementioned above. In addition to that, DCFH-DA staining examined ROS generation. The experimental data corroborated that ALDH2 expression was declined in the tissues of HCl/ethanol-treated rats. Alda-1 ameliorated HCl/ethanol-stimulated gastric mucosal damage, inflammatory response, oxidative stress, NLRP3 inflammasome activation and ferroptosis in rats. Also, the suppressive role of ALDH2 in inflammatory response and oxidative stress was reversed by ferroptosis activator erastin or NLRP3 activator nigericin in HCl/ethanol-challenged GES-1 cells. To be summarized, ALDH2 might play the protective role in the process of GU.

Acetaldehyde dehydrogenase 2 activation attenuates sepsis-induced brain injury through NLRP3 inflammasome regulation

OBJECTIVE

Acetaldehyde dehydrogenase 2 (ALDH2) plays an important part in neuroprotection; however, its effect on sepsis-induced brain injury is nuclear. Our aim is to investigate the potential effect and mechanism of ALDH2 in this condition.

METHODS

We established an animal model using cecal ligation and perforation (CLP). Twenty-four rats were divided into sham group (n = 6), CLP group (n = 6), CLP + Alda-1 group (n = 6) and CLP + Cyanamide (CYA) group (n = 6). Vital signs were monitored, and arterial blood gas analysis, hippocampal histological staining and ALDH2 activity analysis were conducted. Western blot analysis and enzyme-linked immunosorbent assays were also carried out. Lipopolysaccharide (LPS)-treated HT22 cells were employed as an in vitro model of sepsis-induced brain injury, with and without pretreatment with Alda-1 or CYA, to further examine the potential mechanisms. Real-time quantitative polymerase chain reaction and western blot were used to determine the levels of pyrin domain-containing 3 (NLRP3) inflammasome.

RESULTS

We found hippocampal cell injury in the CLP group (p < 0.05), with decreased ALDH2 activity (p < 0.05) and suspected overexpression of NLRP3/caspase-1 axis (p < 0.05). In the group pretreated with Alda-1, there were increased ALDH2 activity (p < 0.05), decreased hippocampal cell damage (p < 0.05), and reduced protein levels of NLRP3, apoptosis-associated speck like protein containing a caspase recruitment domain (ASC), cleaved caspase-1 and Gasdermin D (GSDMD) (p < 0.05). The levels of interleukin 18 (IL-18) and interleukin 1β (IL-1β) were also reduced (p < 0.05). In the group pretreated with CYA, ALDH2 activity was further declined, the cell injury grade increased, and the elevated levels of pyroptosis-related proteins aggravated (p < 0.05). LPS treatment decreased the cell viability and ALDH2 activity of the HT22 cells (p < 0.05), along with increased mRNA levels of the NLRP3 inflammasome, as well as IL-1β and IL-18 (p < 0.05). Western blot further revealed elevated levels of NLRP3, ASC, cleaved caspase-1 and GSDMD (p < 0.05). In the LPS+Alda-1 group, there were increased cell viability (p < 0.05), elevated ALDH2 activity (p < 0.05), and reduced levels of NLRP3 inflammasome and pyroptosis-related proteins (p < 0.05). In the CYA+LPS group, cell viability and ALDH2 activity were further declined (p < 0.05), while levels of NLRP3 /caspase-1 axis were increased (p < 0.05).

CONCLUSIONS

The activation of ALDH2 can attenuate sepsis-induced brain injury, hypothetically through regulation of the NLRP3/caspase-1 signaling pathway. Therefore, ALDH2 could potentially be considered as a new therapeutic target for the treatment of sepsis-induced brain injury.

Emerging Therapy for Diabetic Cardiomyopathy: From Molecular Mechanism to Clinical Practice

Diabetic cardiomyopathy is characterized by abnormal myocardial structure or performance in the absence of coronary artery disease or significant valvular heart disease in patients with diabetes mellitus. The spectrum of diabetic cardiomyopathy ranges from subtle myocardial changes to myocardial fibrosis and diastolic function and finally to symptomatic heart failure. Except for sodium–glucose transport protein 2 inhibitors and possibly bariatric and metabolic surgery, there is currently no specific treatment for this distinct disease entity in patients with diabetes. The molecular mechanism of diabetic cardiomyopathy includes impaired nutrient-sensing signaling, dysregulated autophagy, impaired mitochondrial energetics, altered fuel utilization, oxidative stress and lipid peroxidation, advanced glycation end-products, inflammation, impaired calcium homeostasis, abnormal endothelial function and nitric oxide production, aberrant epidermal growth factor receptor signaling, the activation of the renin–angiotensin–aldosterone system and sympathetic hyperactivity, and extracellular matrix accumulation and fibrosis. Here, we summarize several important emerging treatments for diabetic cardiomyopathy targeting specific molecular mechanisms, with evidence from preclinical studies and clinical trials.

Aldehyde dehydrogenase 2 and NOD-like receptor thermal protein domain associated protein 3 inflammasome in atherosclerotic cardiovascular diseases: A systematic review of the current evidence

Inflammation and dyslipidemia underlie the pathological basis of atherosclerosis (AS). Clinical studies have confirmed that there is still residual risk of atherosclerotic cardiovascular diseases (ASCVD) even after intense reduction of LDL. Some of this residual risk can be explained by inflammation as anti-inflammatory therapy is effective in improving outcomes in subjects treated with LDL-lowering agents. NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation is closely related to early-stage inflammation in AS. Aldehyde dehydrogenase 2 (ALDH2) is an important enzyme of toxic aldehyde metabolism located in mitochondria and works in the metabolism of toxic aldehydes such as 4-HNE and MDA. Despite studies confirming that ALDH2 can negatively regulate NLRP3 inflammasome and delay the development of atherosclerosis, the mechanisms involved are still poorly understood. Reactive Oxygen Species (ROS) is a common downstream pathway activated for NLRP3 inflammasome. ALDH2 can reduce the multiple sources of ROS, such as oxidative stress, inflammation, and mitochondrial damage, thereby reducing the activation of NLRP3 inflammasome. Further, according to the downstream of ALDH2 and the upstream of NLRP3, the molecules and related mechanisms of ALDH2 on NLRP3 inflammasome are comprehensively expounded as possible. The potential mechanism may provide potential inroads for treating ASCVD.

Trimethylamine oxide induces pyroptosis of vascular endothelial cells through ALDH2/ROS/NLRP3/GSDMD pathway

OBJECTIVES

Trimethylamine oxide (TMAO) is a metabolite of intestinal flora and is known to promote the progression of atherosclerotic plaques. However, how TMAO works, including its effect on vascular endothelial cells, is not fully understood. This study aims to explore the biological role of TMAO in human umbilical vein endothelial cells (HUVECs) and the underlying mechanism.

METHODS

Cell pyroptosis and the loss of plasma membrane integrity were induced under TMAO stimulation in HUVECs. The plasma membrane integrity of the cells was measured by Hoechst 33342/propidium iodide (PI) staining and lactate dehydrogenase leakage assay, and the changes in cell morphology were observed by atomic force microscope. The expression of proteins related to pyroptosis was determined by Western blotting or immunofluorescence. Mitochondrial acetaldehyde dehydrogenase 2 (ALDH2) activity in HUVECs was measured by the ALDH2 activity assay kit, and the level of reactive oxygen species (ROS) was detected by fluorescent probe DCFH-DA.

RESULTS

TMAO induced pyroptotic cell death, manifesting by the presence of propidium iodide-positive cells, the leakage of lactate dehydrogenase, the production of N-terminal gasdermin D (GSDMD-N), and the formation of plasma membrane pores. Moreover, TMAO induced elevated expression of inflammasome components, nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), and caspase-1 in cells. TMAO significantly inhibited ALDH2 activity and increased intracellular ROS production. However, the activation of ALDH2 by pharmacological manipulation attenuated TMAO-induced inflammasome activation and GSDMD-N production.

CONCLUSIONS

TMAO induces pyroptosis of vascular endothelial cells through the ALDH2/ROS/NLRP3/GSDMD signaling pathway, which may be a potential therapeutic target for improving the treatment of atherosclerosis.

Targeting Pyroptosis: New Insights into the Treatment of Diabetic Microvascular Complications

Pyroptosis is an inflammatory form of programmed cell death that is dependent on inflammatory caspases, leading to the cleavage of gasdermin D (GSDMD) and increased secretion of interleukin (IL)-1β and IL-18. Recent studies have reported that hyperglycemia-induced cellular stress stimulates pyroptosis, and different signaling pathways have been shown to play crucial roles in regulating pyroptosis. This review summarized and discussed the molecular mechanisms, regulation, and cellular effects of pyroptosis in diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, and diabetic cardiomyopathy. In addition, this review aimed to provide new insights into identifying better treatments for diabetic microvascular complications.

LncRNA-MEG3 attenuates hyperglycemia-induced damage by enhancing mitochondrial translocation of HSP90A in the primary hippocampal neurons

The diabetic cognitive impairments are associated with high-glucose (HG)-induced mitochondrial dysfunctions in the brain. Our previous studies demonstrated that long non-coding RNA (lncRNA)-MEG3 alleviates diabetic cognitive impairments. However, the underlying mechanism has still remained elusive. Therefore, this study was designed to investigate whether the mitochondrial translocation of HSP90A and its phosphorylation are involved in lncRNA-MEG3-mediated neuroprotective effects of mitochondrial functions in HG-treated primary hippocampal neurons and diabetic rats. The primary hippocampal neurons were exposed to 75 mM glucose for 72 h to establish a HG model in vitro. Firstly, the RNA pull-down and RNA immunoprecipitation (RIP) assays clearly indicated that lncRNA-MEG3-associated mitochondrial proteins were Annexin A2, HSP90A, and Plectin. Although HG promoted the mitochondrial translocation of HSP90A and Annexin A2, lncRNA-MEG3 over-expression only enhanced the mitochondrial translocation of HSP90A, rather than Annexin A2, in the primary hippocampal neurons treated with or without HG. Meanwhile, Plectin mediated the mitochondrial localization of lncRNA-MEG3 and HSP90A. Furthermore, HSP90A threonine phosphorylation participated in regulating mitochondrial translocation of HSP90A, and lncRNA-MEG3 also enhanced mitochondrial translocation of HSP90A through suppressing HSP90A threonine phosphorylation. Finally, the anti-apoptotic role of mitochondrial translocation of HSP90A was found to be associated with inhibiting death receptor 5 (DR5) in HG-treated primary hippocampal neurons and diabetic rats. Taken together, lncRNA-MEG3 could improve mitochondrial functions in HG-exposed primary hippocampal neurons, and the underlying mechanisms were involved in enhanced mitochondrial translocation of HSP90A via suppressing HSP90A threonine phosphorylation, which may reveal a potential therapeutic target for diabetic cognitive impairments.

Emerging Role of Epitranscriptomics in Diabetes Mellitus and Its Complications

Diabetes mellitus (DM) and its related complications are among the leading causes of disability and mortality worldwide. Substantial studies have explored epigenetic regulation that is involved in the modifications of DNA and proteins, but RNA modifications in diabetes are still poorly investigated. In recent years, posttranscriptional epigenetic modification of RNA (the so-called 'epitranscriptome') has emerged as an interesting field of research. Numerous modifications, mainly N6 -methyladenosine (m6A), have been identified in nearly all types of RNAs and have been demonstrated to have an indispensable effect in a variety of human diseases, such as cancer, obesity, and diabetes. Therefore, it is particularly important to understand the molecular basis of RNA modifications, which might provide a new perspective for the pathogenesis of diabetes mellitus and the discovery of new therapeutic targets. In this review, we aim to summarize the recent progress in the epitranscriptomics involved in diabetes and diabetes-related complications. We hope to provide some insights for enriching the understanding of the epitranscriptomic regulatory mechanisms of this disease as well as the development of novel therapeutic targets for future clinical benefit.

lncRNA GAS5 promotes pyroptosis in COPD by functioning as a ceRNA to regulate the miR‑223‑3p/NLRP3 axis

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible and progressive airflow limitation and encompasses a spectrum of diseases, including chronic obstructive bronchitis and emphysema. Pyroptosis is a unique form of inflammatory cell death mediated by the activation of caspase-1 and inflammasomes. The long non-coding RNA (lncRNA) growth arrest-specific 5 (GAS5) is a well-documented tumor suppressor, which is associated with cell proliferation and death in various diseases. The aim of the present study was to evaluate whether lncRNA GAS5 is associated with the pyroptosis in COPD. To create a COPD cell model, MRC-5 cells were treated with 10 µg/ml lipopolysaccharide (LPS) for 48 h. Then the level of pro-caspase 1, caspase 1, IL-1β, IL-18, NLRP3 and cleaved gasdermin D (GSDMD) was examined by western blotting. GAS5 mRNA level was detected by qualitative PCR following LPS treatment in MRC-5 cells. Subsequently, IL-2, IL-6, IL-10 and TNF-α in MRC-5 cells was measured by ELISA. Then the proliferation ability of MRC-5 cells was detected by CCK-8. Cell death was detected by TUNEL assay. LDH release was measured using an LDH Cytotoxicity Assay kit. The Magna RIP kit was used to validate the interaction between GAS5 and miR-223-3p. The present study revealed that increased expression levels of caspase-1, IL-1β, IL-18 and cleaved GSDMD were observed in LPS-treated MRC-5 cells, indicating that pyroptosis is involved in COPD progression. Additionally, LPS induced the increase in GAS5 mRNA expression levels and the release of inflammatory factors (IL-2, IL-6, IL-10 and TNF-α), suggesting that GAS5 is implicated in pyroptosis in COPD. Furthermore, upregulation of GAS5 promoted cell death and inhibited proliferation in the MRC-5 cell line. Additionally, increased GAS5 expression significantly promoted the production of caspase-1, IL-1β, IL-18, cleaved GSDMD and NLR pyrin domain containing protein 3 (NLRP3). A dual-luciferase assay demonstrated that GAS5 could directly bind to microRNA-223-3p (miR-223-3p), and NLRP3 is a direct target of miR-223-3p. Furthermore, GAS5 reduced the expression levels of miR-223-3p, while it increased the expression levels of NLRP3. The present study concluded that lncRNA GAS5 promoted pyroptosis in COPD by targeting the miR-223-3p/NLRP3 axis, implying that GAS5 could be a potential target for COPD.

Aldehyde dehydrogenase 2 and arrhythmogenesis

Cardiac arrhythmia is a common cardiovascular disease that leads to considerable economic burdens and significant global public health challenges. Despite the remarkable progress made in recent decades, antiarrhythmic therapy remains suboptimal. Aldehyde dehydrogenase 2 (ALDH2), a critical detoxifying enzyme, catalyzes toxic aldehydes and protects individuals from damages caused by oxidative stress. Accumulating evidence has demonstrated that ALDH2 activation has potential antiarrhythmic benefits. The correlation between ALDH2 deficiency and arrhythmogenesis has been widely recognized. In this review, we summarize recent researches on the potential roles of ALDH2 activation and antiarrhythmic protection, as well as the role played by the ALDH2*2 polymorphism (rs671) in promoting arrhythmic risk. Additionally, we discuss important new findings illustrating the use of ALDH2 activators, which may prove to be promising antiarrhythmic therapy agents.

KDM3A Inhibition Ameliorates Hyperglycemia-Mediated Myocardial Injury by Epigenetic Modulation of Nuclear Factor Kappa-B/P65

Objectives

Even after the glucose level returns to normal, hyperglycemia-induced cardiac dysfunction as well as reactive oxygen species (ROS) generation, inflammatory responses, and apoptosis continued deterioration, showing a long-lasting adverse effect on cardiac function and structure. We aimed to unveil the molecular and cellular mechanisms underlying hyperglycemia-induced persistent myocardial injury and cardiac dysfunction.

Methods and Results

Recently, the accumulated evidence indicated epigenetic regulation act as a determining factor in hyperglycemia-induced continuous cardiovascular dysfunction. As an important histone demethylase, the expression of lysine-specific demethylase 3A (KDM3A) was continually increased, accompanied by a sustained decline of H3K9me2 levels in diabetic myocardium even if received hypoglycemic therapy. Besides, by utilizing gain- and loss-of-functional approaches, we identified KDM3A as a novel regulator that accelerates hyperglycemia-mediated myocardial injury by promoting ROS generation, aggregating inflammatory reaction, and facilitating cell apoptosis in vitro and in vivo. The KDM3A inhibition could significantly ameliorate the adverse effect of hyperglycemia in both diabetes model and diabetic intensive glycemic control model. Mechanically, our data uncovered that KDM3A could promote the expression and transcriptional activity of nuclear factor kappa-B (NF-κB/P65), and the succedent rescue experiments further verified that KDM3A regulates hyperglycemia-induced myocardial injury in an NF-κB/P65 dependent manner.

Conclusion

This study revealed histone-modifying enzymes KDM3A drives persistent oxidative stress, inflammation, apoptosis, and subsequent myocardial injury in the diabetic heart by regulating the transcription of NF-κB/P65.

Crosstalk of pyroptosis, ferroptosis, and mitochondrial aldehyde dehydrogenase 2-related mechanisms in sepsis-induced lung injury in a mouse model

Acute lung injury (ALI) is a common complication of sepsis. Mitochondrial aldehyde dehydrogenase 2 (ALDH2), an enzyme involved in aldehyde metabolism, exerts a protective effect against sepsis. This study investigated the possible mechanisms underlying the roles of ALDH2, pyroptosis, and ferroptosis in sepsis-induced lung injury. A mouse model of sepsis-induced lung injury was established by cecal ligation and puncture (CLP); lung morphology was evaluated by calculation of lung coefficient, hematoxylin–eosin staining, and electron microscopy. Malondialdehyde (MDA), reactive oxygen species (ROS), and 4-hydroxy-2-nonenal (4-HNE) protein expression levels were used to detect the level of lipid oxidative stress. In addition, total iron was detected using an iron detection kit, and the expression of ferroptosis-related proteins (PTGS2, GPX4), pyroptosis-related proteins, and ALDH2 was examined using western blotting. To further examine the likely mechanisms, the ferroptosis inhibitor ferrostatin 1 (Fer-1), NLRP3 inflammasome inhibitor MCC950, and ALDH2 activator Alda-1 were added. CLP-treated mice exhibited destruction of lung tissue morphology, lipid peroxidation injury, iron content, and increased lung PTGS2 protein expression, accompanied by a decrease in GPX4 protein expression. CLP also downregulated ALDH2 expression and increased the expression of the NLRP3 inflammasome and pyroptosis-related proteins. These adverse effects of CLP were relieved by Alda-1, Fer-1, and MCC950 treatment. In conclusion, both pyroptosis and ferroptosis participate in CLP-induced ALI, and ALDH2 plays a protective role by reducing pyroptosis and ferroptosis. This study provides a scientific basis for the treatment of lung injury in sepsis.

Oxidative Stress Signaling Mediated Pathogenesis of Diabetic Cardiomyopathy

As a serious cardiovascular complication, diabetic cardiomyopathy (DCM) refers to diabetes-related changes in myocardial structure and function, which is obviously different from those cardiomyopathy secondary to hypertension, coronary heart disease, and valvular disease. The clinical features of DCM are left ventricular hypertrophy, myocardial fibrosis, and impaired diastolic function. DCM will lead to cardiac dysfunction, eventually progress to cardiac arrhythmia, heart failure, and sudden cardiac death. At present, the pathogenesis of DCM is complex and not fully elucidated, and oxidative stress (OS), inflammatory response, glucolipid metabolism disorder, etc., are considered as the potential pathophysiological mechanisms. As a consequence, there is no specific and effective treatment for DCM. OS refers to the imbalance between reactive oxygen species (ROS) accumulation and scavenging, oxidation, and antioxidants in vivo, which is widely studied in DCM. Numerous studies have pointed out that regulating the OS signaling pathways and reducing the generation and accumulation of ROS are potential directions for the treatment of DCM. This review summarizes the major OS signaling pathways that are related to the pathogenesis of DCM, providing ideas about further research and therapy.

METTL14 suppresses pyroptosis and diabetic cardiomyopathy by downregulating TINCR lncRNA

N6-methyladenosine (m6A) is one of the most important epigenetic regulation of RNAs, such as lncRNAs. However, the underlying regulatory mechanism of m6A in diabetic cardiomyopathy (DCM) is very limited. In this study, we sought to define the role of METTL14-mediated m6A modification in pyroptosis and DCM progression. DCM rat model was established and qRT-PCR, western blot, and immunohistochemistry (IHC) were used to detect the expression of METTL14 and TINCR. Gain-and-loss functional experiments were performed to define the role of METTL14-TINCR-NLRP3 axis in pyroptosis and DCM. RNA pulldown and RNA immunoprecipitation (RIP) assays were carried out to verify the underlying interaction. Our results showed that pyroptosis was tightly involved in DCM progression. METTL14 was downregulated in cardiomyocytes and hear tissues of DCM rat tissues. Functionally, METTL14 suppressed pyroptosis and DCM via downregulating lncRNA TINCR, which further decreased the expression of key pyroptosis-related protein, NLRP3. Mechanistically, METTL14 increased m6A methylation level of TINCR gene, resulting in its downregulation. Moreover, the m6A reader protein YTHDF2 was essential for m6A methylation and mediated the degradation of TINCR. Finally, TINCR positively regulated NLRP3 by increasing its mRNA stability. To conclude, our work revealed the novel role of METTL14-mediated m6A methylation and lncRNA regulation in pyroptosis and DCM, which could help extend our understanding the epigenetic regulation of pyroptosis in DCM progression.

Canagliflozin mitigates ferroptosis and improves myocardial oxidative stress in mice with diabetic cardiomyopathy

Canagliflozin (Cana), an anti-diabetes drug belongs to sodium-glucose cotransporter 2 inhibitor, is gaining interest because of its extra cardiovascular benefits. Ferroptosis is a new mode of cell death, which can promote the occurrence of diabetic cardiomyopathy (DCM). Whether Cana can alleviate DCM by inhibiting ferroptosis is the focus of this study. Here, we induced DCM models in diabetic C57BL6 mice and treated with Cana. Meanwhile, in order to exclude its hypoglycemic effect, the high glucose model in H9C2 cells were established. In the in vivo study, we observed that Cana could effectively alleviate the damage of cardiac function in DCM mice, including the increasing of lactate dehydrogenase (LDH) and cardiac troponin I (cTnI), the alleviating of myocardial fiber breakage, inflammation, collagen fiber deposition and mitochondrial structural disorder. We evaluated reactive oxygen species (ROS) levels by DCFH-DA and BODIPY 581/591 C11, in vitro Cana reduced ROS and lipid ROS in H9C2 cells induced by high glucose. Meanwhile, JC-1 fluorochrome assay showed that the decreased mitochondrial membrane potential (MMP) was increased by Cana. Furthermore, the inhibitory effects of Cana on myocardial oxidative stress and ferroptosis were verified in vivo and in vitro by protein carbonyl (PCO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH). As a key inducer of ferroptosis, the deposition of total iron and Fe²⁺ can be inhibited by Cana both in vivo and in vitro. In addition, western blot results indicated that the expression of ferritin heavy-chain (FTN-H) was down-regulated, and cystine-glutamate antiporter (xCT) was up-regulated by Cana in DCM mice and cells, suggesting that Cana inhibit ferroptosis by balancing cardiac iron homeostasis and promoting the system Xc^-/GSH/GPX4 axis in DCM. These findings underscore the fact that ferroptosis plays an important role in the development and progression of DCM and targeting ferroptosis may be a novel strategy for prevention and treatment. In conclusion, Cana may exert some of its cardiovascular benefits by attenuating ferroptosis.

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

Diabetic mellitus (DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications (DCCs) as major causes of death in diabetic patients with diabetic cardiomyopathy (DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart failure. Various forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis, necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac disease. Evidence has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly, published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

Sodium Glucose Cotransporter 1 (SGLT1) Inhibitors in Cardiovascular Protection: Mechanism Progresses and Challenges

In recent years, multiple clinical trials have shown that sodium glucose cotransporter 1 (SGLT1) inhibitors have significant beneficial cardiovascular effects. This includes reducing the incidence of cardiovascular deaths and heart failure hospitalizations in people with and without diabetes, as well as those with and without generalized heart failure. The exact mechanism responsible for these beneficial effects is not completely understood. To explain the cardiovascular protective effects of SGLT1 inhibitors, several potential arguments have been proposed, including decreasing oxidative stress, regulating cardiac glucose uptake, preventing ischemia/reperfusion injury, alleviating the activation of cardiac fibroblasts, attenuating apoptosis, reducing intermittent high glucose-induced pyroptosis, ameliorating cardiac hypertrophy, attenuating arrhythmic vulnerabilities, and improving left ventricular systolic disorder. This article reviews the advantages and disadvantages of these mechanisms, and attempts to synthesize and prioritize mechanisms related to the reduction of clinical events.

Pyroptosis: A possible link between obesity-related inflammation and inflammatory diseases

The main manifestation of obesity is persistent low-level inflammation and insulin resistance, which is an important factor inducing or promoting other obesity-related diseases. As a proinflammatory programmed cell death, pyroptosis plays an important role, especially in the activation and regulation of the NLRP3 inflammasome pathway. Pyroptosis is associated with the pathogenesis of many chronic inflammatory diseases and is characterized by the formation of micropores in the plasma membrane and the release of a large number of proinflammatory cytokines. This article mainly introduces the main pathways and key molecules of pyroptosis and focuses on the phenomenon of pyroptosis in obesity. It is suggested that the regulation of pyroptosis-related targets may become a new potential therapy for the prevention and treatment of systemic inflammatory response caused by obesity, and we summarize the potential molecular substances that may be beneficial to obesity-related inflammatory diseases through target pyroptosis.

Rutin alleviates cardiomyocyte injury induced by high glucose through inhibiting apoptosis and endoplasmic reticulum stress

Diabetic cardiomyopathy is a common complication of diabetes, in which endoplasmic reticulum stress (ERS) serves an important role. Rutin can treat the myocardial dysfunction of diabetic rats. However, to the best of our knowledge, studies on the effects of Rutin on myocardial injury caused by diabetes from the perspective of ERS have not previously been reported. In the present study, the role of rutin in the regulation of ERS in myocardial injury was assessed. Different high glucose concentrations were used to treat H9C2 myoblast cells to establish a myocardial damage model. A cell counting kit-8 assay was used to determine cell viability. A lactate dehydrogenase kit was used to detect cytotoxicity. Apoptosis levels were determined using a TUNEL assay. Western blotting was used to determine the expression levels of apoptosis-related proteins and ERS-related proteins, including heat shock protein A family member 5, inositol-requiring enzyme-1α, X-box binding protein 1, activating transcription factor 6, C/EBP-homologous protein (CHOP), cleaved caspase-12 and caspase-12. The anti-apoptotic and anti-ERS effects of Rutin on H9C2 cardiac cells induced by high glucose were examined after the administration of the ERS activator thapsigargin (TG). The results indicated that rutin could dose-dependently inhibit the level of apoptosis and ERS induced by high glucose in H9C2 cells. After administration of the ERS activator TG, it was demonstrated that TG could reverse the anti-apoptotic and anti-ERS effects of rutin on H9C2 cells stimulated with high glucose. Collectively, the present results suggested that rutin may alleviate cardiomyocyte model cell injury induced by high glucose through the inhibition of apoptosis and ERS.

Aldehyde dehydrogenase 2 alleviates monosodium iodoacetate-induced oxidative stress, inflammation and apoptosis in chondrocytes via inhibiting aquaporin 4 expression

BACKGROUND

Knee osteoarthritis (KOA) is a common cause of disability among the elderly. We aimed to explore the effects of aldehyde dehydrogenase (ALDH) 2 on the progression of KOA and identifying the potential mechanisms.

METHODS

First, ALDH2 expression in knee joint effusion of patients with KOA and the levels of oxidative stress-related markers were determined. After ALDH2 overexpression in monosodium iodoacetate (MIA)-treated SW1353 cells, cell viability was tested with CCK-8 assay. Subsequently, oxidative stress and inflammation-associated factors were measured. Meanwhile, cell apoptosis was assessed with TUNEL staining and expression of apoptosis-related proteins was detected by western blotting. To analyze the mechanism of ALDH2 in KOA, aquaporin 4 (AQP4) expression was determined using western blotting following ALDH2-upregulation. Subsequently, AQP4 was overexpressed to evaluate the changing of oxidative stress, inflammation and apoptosis in SW1353 cells exposed to MIA with ALDH2 overexpression.

RESULTS

Results indicated that knee joint effusion with higher ALDH2 expression displayed lower oxidative stress. In addition, significantly upregulated ALDH2 expression was observed in MIA-treated SW1353 cells. ALDH2 overexpression oxidative stress, inflammation and apoptosis in SW1353 cells exposed to MIA. Moreover, MIA-triggered elevated expression of AQP4, which was reduced by ALDH2 overexpression. By contrast, AQP4-upregulation abrogated the inhibitory effects of ALDH2 on oxidative stress, inflammation and apoptosis in MIA-induced SW1353 cells.

CONCLUSIONS

ALDH2 inactivates the expression of AQP4, by which mechanism the MIA-induced oxidative stress, inflammation and apoptosis injuries were alleviated, which provides a novel insight for understanding the mechanism of KOA and a promising target for the treatment of this disease.

Protective effect of aldehyde dehydrogenase 2 against rat corneal dysfunction caused by streptozotocin-induced type I diabetes

Aldehyde dehydrogenase 2 plays a pivotal role in detoxifying aldehydes, and our previous study revealed that aldehyde dehydrogenase 2 could alleviate diabetic retinopathy-associated damage. We aimed to characterize the potential role of aldehyde dehydrogenase 2 in diabetic keratopathy. Twenty-four rats with streptozotocin-induced (60 mg/kg, single intraperitoneal injection) type 1 diabetes mellitus (T1DM) were divided the T1DM group and the T1DM + Alda1 (an activator of aldehyde dehydrogenase 2) group (5 mg/kg/d, intraperitoneal injection, 1/2/3 months), while an additional 12 healthy rats served as the control group. Corneal morphology was examined in vivo and in vitro at one, two, and three months after T1DM induction. Additionally, serum inflammatory factors were measured by ELISA, and the expression of corneal vascular endothelial growth factor A (VEGF-A) and aldehyde dehydrogenase 2 was measured by immunofluorescence staining. Corneal cell death was evaluated by terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining. Slit lamp analysis showed that the area of corneal epithelial cell injury in the T1DM + Alda1 group was significantly smaller than that in the T1DM group at one and two months after T1DM induction (all P < 0.05). OCT analysis and HE staining showed that the central corneal thickness (indication of corneal edema) and the epithelial keratinization level in the T1DM + Alda1 group was evidently decreased compared with those in the T1DM group (all P < 0.05). The serum inflammatory factors interleukin-1 and interleukin-6 were significantly upregulated in the T1DM group compared with the T1DM + Alda1 group at three months after T1DM induction (all P < 0.05), while there were no differences in SOD or TNF-α levels among all groups. Furthermore, corneal VEGF-A expression and corneal cell death in the T1DM + Alda1 group were dramatically reduced compared to those in the T1DM group (all P < 0.05). In conclusion, the aldehyde dehydrogenase 2 agonist Alda1 attenuated rat corneal dysfunction induced by T1DM by alleviating corneal edema, decreasing corneal cell death, and downregulating corneal VEGF-A expression.

Vincristine attenuates cardiac fibrosis through the inhibition of NLRP3 inflammasome activation

Vincristine (VCR) is widely used in cancer therapies, although its benefits on cardiac fibrosis remain unknown. Here, we investigated VCR's efficacy on cardiac fibrosis and elucidated the underlying mechanism of action. Network pharmacology was employed to predict the mechanism of VCR action on cardiac fibrosis. We induced cardiac fibrosis in adult male Sprague-Dawley (SD) rats via isoproterenol (ISO) injection, followed by treatment with VCR or vehicle. After 10 days of treatment, VCR-treated rats exhibited a significantly lower heart/body weight ratio relative to those treated with the vehicle. Moreover, cardiac fibrosis was alleviated in VCR-treated rats relative to vehicle-treated rats. The results revealed the down-regulation of mature caspase-1, interleukin (IL)-1β, and IL-18 in VCR-treated rats relative to vehicle-treated rats. We also observed less colocalization between the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a CARD (ASC) in VCR-treated rats compared with vehicle-treated rats. We then cultured neonatal rat cardiac fibroblasts (NRCFs) and exposed them to lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in the presence or absence of VCR. The results indicated that VCR mediated the down-regulation of caspase-1, IL-1β, and IL-18 and the colocalization of NLRP3 and ASC in LPS+ATP-stimulated cardiac fibroblasts (CFs). We found evidence that VCR attenuates cardiac fibrosis by directly suppressing the activation of the NLRP3 inflammasome. These findings provide novel insights into VCR's mechanism of action in alleviating cardiac fibrosis.

Therapeutic potential of targeting oxidative stress in diabetic cardiomyopathy

Even in the absence of coronary artery disease and hypertension, diabetes mellitus (DM) may increase the risk for heart failure development. This risk evolves from functional and structural alterations induced by diabetes in the heart, a cardiac entity termed diabetic cardiomyopathy (DbCM). Oxidative stress, defined as the imbalance of reactive oxygen species (ROS) has been increasingly proposed to contribute to the development of DbCM. There are several sources of ROS production including the mitochondria, NAD(P)H oxidase, xanthine oxidase, and uncoupled nitric oxide synthase. Overproduction of ROS in DbCM is thought to be counterbalanced by elevated antioxidant defense enzymes such as catalase and superoxide dismutase. Excess ROS in the cardiomyocyte results in further ROS production, mitochondrial DNA damage, lipid peroxidation, post-translational modifications of proteins and ultimately cell death and cardiac dysfunction. Furthermore, ROS modulates transcription factors responsible for expression of antioxidant enzymes. Lastly, evidence exists that several pharmacological agents may convey cardiovascular benefit by antioxidant mechanisms. As such, increasing our understanding of the pathways that lead to increased ROS production and impaired antioxidant defense may enable the development of therapeutic strategies against the progression of DbCM. Herein, we review the current knowledge about causes and consequences of ROS in DbCM, as well as the therapeutic potential and strategies of targeting oxidative stress in the diabetic heart.

Role of Pyroptosis in Diabetes and Its Therapeutic Implications

Pyroptosis is mainly considered as a new pro-inflammatory mediated-programmed cell death. In addition, pyroptosis is described by gasdermin-induced pore formation on the membrane, cell swelling and rapid lysis, and several pro-inflammatory mediators interleukin-1β (IL-1β) and interleukin-18 (IL-18) release. Extensive studies have shown that pyroptosis is commonly involved by activating the caspase-1-dependent canonical pathway and caspase-4/5/11-dependent non-canonical pathway. However, pyroptosis facilitates local inflammation and inflammatory responses. Current researches have reported that pyroptosis promotes the progression of several diabetic complications. Emerging studies have suggested that some potential molecules targeting the pyroptosis and inflammasome signaling pathways could be a novel therapeutic avenue for managing and treating diabetes and its complications in the near future. Our narrative review concisely describes the possible mechanism of pyroptosis and its progressive understanding of the development of diabetic complications.

Inhibition of SGLT1 protects against glycemic variability-induced cardiac damage and pyroptosis of cardiomyocytes in diabetic mice

AIMS

Glycemic variability has been shown to be more harmful in the development of diabetic complication than sustained chronic hyperglycemia. In this present study, we tried to reveal the effects of glycemic variability on cardiac damage in diabetic mice and investigate whether sodium-glucose cotransporter 1 (SGLT1), an important cardiac glucose transporter, functions as an important mediator in the process.

MATERIALS AND METHODS

Type 2 diabetes mellitus (DM) mice were induced by a high-fat diet and intraperitoneal injection of streptozotocin (STZ), and then glycemic variability in type 2 diabetes mellitus (GVDM) was induced by alternately injecting insulin and glucose to DM mice. In order to determine the roles of SGLT1 in GVDM mice, SGLT1 inhibition was performed using shRNA against SGLT1. The blood glucose level, the cardiac function and myocardial injury were assessed. And the expressions of SGLT1 and the activations of NLRP3/caspase-1 pathway and NF-κB in left ventricular tissues were measured.

KEY FINDINGS

The results showed that SGLT1 was highly expressed in heart of GVDM mice compared to control and DM groups, and knockdown of SGLT1 reduced glycemic variability in GVDM mice. Moreover, glycemic variability impaired cardiac function, aggravated cardiac injury and induced NLRP3/caspase-1-mediated inflammatory response and pyroptosis. And knockdown of SGLT1 significantly attenuated the cardiac damages that induced by glycemic variability.

SIGNIFICANCE

The results indicated that glycemic variability could cause cardiac damage and induce inflammatory response and pyroptosis of cardiomyocytes in diabetic mice, which could be partially blocked by SGLT1 silence.

The NLRP3 inflammasome: Multiple activation pathways and its role in primary cells during ventricular remodeling

Inflammasomes are a group of multiprotein signaling complexes located in the cytoplasm. Several inflammasomes have been identified, including NLRP1, NLRP2, NLRP3, AIM2, and NLRC4. Among them, NLRP3 was investigated in most detail, and it was reported that it can be activated by many different stimuli. Increased NLRP3 protein expression and inflammasome assembly lead to caspase-1 mediated maturation and release of IL-1β, which triggers inflammation and pyroptosis. The activation of the NLRP3 inflammasome has been widely reported in studies of tumors and neurological diseases, but relatively few studies on the cardiovascular system. Ventricular remodeling (VR) is an important factor contributing to heart failure (HF) after myocardial infarction (MI). Consequently, delaying VR is of great significance for improving heart function. Studies have shown that the NLRP3 inflammasome plays an essential role in the process of VR. Here, we reviewed the latest studies on the activation pathway of the NLRP3 inflammasome, focusing on the effects of the NLRP3 inflammasome in primary cells during VR, and finally discuss future research directions in this field.

Corrigendum to "ALDH2 Overexpression Alleviates High Glucose-Induced Cardiotoxicity by Inhibiting NLRP3 Inflammasome Activation"

[This corrects the article DOI: 10.1155/2019/4857921.].

Changes of Necroptosis in Irbesartan Medicated Cardioprotection in Diabetic Rats

BACKGROUND

Diabetic cardiomyopathy (DCM) is strongly linked to microvascular disease, renin-angiotensin system (RAS) activation, cardiac inflammation and cell apoptosis. Irbesartan is an angiotensin II (Ang II) receptor antagonist in RAS system, which inhibited the conversion of Ang I into Ang II, while the specific mechanism is still obscure.

OBJECTIVE

This study aims to investigate the expressions necroptosis RIP1-RIP3-MLKL pathway in myocardium of diabetic rats, and the protective action of irbesartan on myocardial damage.

MATERIALS AND METHODS

In our study, 30 Sprague-Dawley rats were divided into 5 groups: CON4W, high glucose and high caloric (HC4W), diabetes mellitus 4 weeks (DM4W group), diabetes mellitus 8 weeks (DM8W group), and irbesartan diabetes 8 weeks (Ir DM8W group).

RESULTS

We discovered that as diabetes progresses, the rats gradually lost weight, the HW/BW ratio were increased gradually, and the cardiac function became worse accompanied with the aggravation of inflammatory injury. Meanwhile, the myocardial fibers and cells were disordered, and the expression of positive substances, RIP1 and RIP3 increased significantly. The mRNA and protein levels of myocardial RIP1, RIP3 and MLKL were all increased with the progression of DM. After the intervention of irbesartan in diabetic rats, the cardiac function was improved, whereas inflammatory injury and HW/BW ratio were decreased. Also, the myocardial fibrosis injury was attenuated, and the PAS positive substances, RIP1 and RIP3 were significantly decreased. The curative effect of irbesartan was related to decreased myocardial RIP1, RIP3 and MLKL mRNA and protein levels.

CONCLUSION

In conclusion, irbesartan has a cardioprotective effect on the diabetic rats, and its mechanism may be connected with inhibition of RIP1-RIP3-MLKL pathway.

Dihydromyricetin attenuates neuropathic pain via enhancing the transition from M1 to M2 phenotype polarization by potentially elevating ALDH2 activity in vitro and vivo

Background

Treatment for neuropathic pain as a refractory disease remains unsatisfactory and represents a significant clinical challenge. A highly effective drug is thus urgently needed for neuropathic pain treatment. Dihydromyricetin (DMY) is a flavonoid with a wide range of biological activities. The purpose of this research is to explore the effects of DMY on neuropathic pain and the underlying mechanism of its effect.

Methods

The effect of DMY was investigated in BV-2 cells and lipopolysaccharide (LPS)-induced BV-2 cells. A neuropathic pain model was established via spared nerve injury (SNI) surgery in mice, and the protein expression level was detected via Western blot assay. The percent of M1 and M2 phenotype polarization cells were detected via flow cytometry assay. Immunochemical staining assay was also performed to measure the marker levels of the M1 and M2 phenotype polarization cells and aldehyde dehydrogenase 2 (ALDH2) level, and mechanical pain sensitivity was evaluated via measurement of the mechanical withdrawal threshold.

Results

We found that DMY promoted the transition from M1 to M2 polarization and upregulated the ALDH2 level in vitro and vitro. ALDA-1, an ALDH2 agonist, promoted the switching from M1 to M2 polarization in vivo and vitro. DMY alleviated pain hypersensitivity induced by SNI via enhancing M2 phenotype polarization by elevating ALDH2 activity in mice. After DMY- or ALDA-1-microglia were injected into SNI-induced pain hypersensitive mice, the mechanical withdrawal threshold was increased significantly when compared with the SNI group.

Conclusions

Our data demonstrated that DMY alleviated neuropathic pain via enhancing the polarization transition from the M1 to M2 phenotype by potentially elevating ALDH2 activity in vitro and vivo. DMY- or ALDA-1-microglia may have alleviative effects on neuropathic pain. The findings herein provide a promising avenue for neuropathic pain treatment, suggesting a new target, ALDH2, in the treatment of neuropathic pain.

Does the Act of Copulation per se, without Considering Seminal Deposition, Change the Expression of Genes in the Porcine Female Genital Tract?

Semen—through its specific sperm and seminal plasma (SP) constituents—induces changes of gene expression in the internal genital tract of pigs, particularly in the functional sperm reservoir at the utero-tubal junction (UTJ). Although seminal effects are similarly elicited by artificial insemination (AI), major changes in gene expression are registered after natural mating, a fact suggesting the act of copulation induces per se changes in genes that AI does not affect. The present study explored which pathways were solely influenced by copulation, affecting the differential expression of genes (DEGs) of the pre/peri-ovulatory genital tract (cervix, distal uterus, proximal uterus and UTJ) of estrus sows, 24 h after various procedures were performed to compare natural mating with AI of semen (control 1), sperm-free SP harvested from the sperm-peak fraction (control 2), sperm-free SP harvested from the whole ejaculate (control 3) or saline-extender BTS (control 4), using a microarray chip (GeneChip^® porcine gene 1.0 st array). Genes related to neuroendocrine responses (ADRA1, ADRA2, GABRB2, CACNB2), smooth muscle contractility (WNT7A), angiogenesis and vascular remodeling (poFUT1, NTN4) were, among others, overrepresented with distal and proximal uterine segments exhibiting the highest number of DEGs. The findings provide novel evidence that relevant transcriptomic changes in the porcine female reproductive tract occur in direct response to the specific act of copulation, being semen-independent.

Circular RNA circFAT1(e2) Promotes Osteosarcoma Progression and Metastasis by Sponging miR-181b and Regulating HK2 Expression

As a subclass of noncoding RNAs, circular RNAs (circRNAs) have been demonstrated to play a critical role in regulating gene expression in eukaryotes. Recent studies have revealed the pivotal functions of circRNAs in cancer progression. Nevertheless, how circRNAs participate in osteosarcoma (OS) development and progression are not well understood. In the present study, we identified a circRNA circFAT1(e2) with an upregulated expression level in OS tissues. By functional experiments, we found that circFAT1(e2) depletion significantly suppressed the proliferation and reduced migration in OS. In terms of mechanism, we found that circFAT1(e2) inhibited miR-181b, while miR-181b targeted HK2. By releasing the inhibition of miR-181b on HK2 expression, leading to attenuated OS progression. Mechanistic investigations suggested that circFAT1(e2) served as a competing endogenous RNA (ceRNA) of miR-181b to enhance HK2 expression. On the whole, our study indicated that circFAT1(e2) exerted oncogenic roles in OS and suggested the circFAT1(e2)/miR-181b/HK2 axis might be a potential therapeutic target.

Mechanisms and Therapeutic Regulation of Pyroptosis in Inflammatory Diseases and Cancer

Programmed Cell Death (PCD) is considered to be a pathological form of cell death when mediated by an intracellular program and it balances cell death with survival of normal cells. Pyroptosis, a type of PCD, is induced by the inflammatory caspase cleavage of gasdermin D (GSDMD) and apoptotic caspase cleavage of gasdermin E (GSDME). This review aims to summarize the latest molecular mechanisms about pyroptosis mediated by pore-forming GSDMD and GSDME proteins that permeabilize plasma and mitochondrial membrane activating pyroptosis and apoptosis. We also discuss the potentiality of pyroptosis as a therapeutic target in human diseases. Blockade of pyroptosis by compounds can treat inflammatory disease and pyroptosis activation contributes to cancer therapy.