Transcriptomic effects of adenosine 2A receptor deletion in healthy and endotoxemic murine myocardium

S100A9 as a Key Myocardial Injury Factor Interacting with ATP5 Exacerbates Mitochondrial Dysfunction and Oxidative Stress in Sepsis-Induced Cardiomyopathy

Purpose

Sepsis-induced cardiomyopathy (SICM) is a prevalent cardiac dysfunction caused by sepsis. Mitochondrial dysfunction is a crucial pathogenic factor associated with adverse cardiovascular adverse events; however, research on SICM remains insufficient.

Methods

To investigate the factors contributing to the pathological progression of SICM, we performed a comprehensive analysis of transcriptomic data from the GEO database using bioinformatics and machine learning techniques. CRISPR-Cas9 S100A9 knockout mice and primary cardiomyocytes were exposed to lipopolysaccharide to simulate SICM. Transcriptome analysis and mass spectrometry of primary cardiomyocytes were used to determine the potential pathogenic mechanisms of S100A9. The mitochondrial ultrastructure and mitochondrial membrane potential (MMP) were detected using transmission electron microscopy and flow cytometry, respectively. Pink1/Parkin and Drp1 proteins were detected using Western blotting to evaluate mitochondrial autophagy and division. The mtDNA and mRNA levels of mitochondrial transcription factors and synthases were evaluated using real-time polymerase chain reaction.

Results

Bioinformatics analysis identified 12 common differentially expressed genes, including SERPINA3N, LCN2, MS4A6D, LRG1, OSMR, SOCS3, FCGR2b, S100A9, S100A8, CASP4, ABCA8A, and NFKBIZ. Significant S100A9 upregulation was closely associated with myocardial injury exacerbation and cardiac function deterioration. GSEA revealed that myocardial contractile function, oxidative stress, and mitochondrial function were significantly affected by S100A9. Knocking out S100A9 alleviates the inflammatory response and mitochondrial dysfunction. The interaction of S100A9 with ATP5 enhanced mitochondrial division and autophagy, inhibited MMP and ATP synthesis, and induced oxidative stress, which are related to the Nlrp3-Nfkb-Caspase1 and Drp1-Pink1-Parkin signaling pathways. The expression of mitochondrial transcription factors (TFAM and TFBM) and ATP synthetases (ATP6 and ATP8, as well as COX1, COX2, and COX3) was further suppressed by S100A9 in SICM. Targeted S100A9 inhibition by paquinimod partially reversed myocardial mitochondrial dysfunction and oxidative stress.

Conclusion

The interaction of S100A9 with ATP5 exacerbates myocardial damage in sepsis by inducing mitochondrial dysfunction and oxidative stress.

Early cardiac aging linked to impaired stress-resistance and transcriptional control of stress response, quality control and mitochondrial pathways

Phenotypic and transcriptomic evidence of early cardiac aging, and associated mechanisms, were investigated in young to middle-aged male mice (C57Bl/6; ages 8, 16, 32, 48 wks). Left ventricular gene expression (profiled via Illumina MouseWG-6 BeadChips), contractile and coronary function, and stress-resistance were assessed in Langendorff perfused hearts under normoxic conditions and following ischemic insult (20 min global ischemia-45 min reperfusion; I-R). Baseline or normoxic contractile function was unaltered by age, while cardiac and coronary 'reserves' (during β-adrenoceptor stimulation; 1 μM isoproterenol) declined by 48 wks. Resistance to I-R injury fell from 16 to 32 wks. Age-dependent transcriptional changes In un-stressed hearts were limited to 104 genes (>1.3-fold; 0.05 FDR), supporting: up-regulated innate defenses (glutathione and xenobiotic metabolism, chemotaxis, interleukins) and catecholamine secretion; and down-regulated extracellular matrix (ECM), growth factor and survival (PI3K/Akt) signaling. In stressed (post-ischemic) myocardium, ∼15-times as many genes (1528) were age-dependent, grouped into 6 clusters (>1.3-fold change; 0.05 FDR): most changing from 16 wks (45 % up/44 % down), a further 5 % declining from 32 wks. Major age-dependent Biological Processes in I-R hearts reveal: declining ATP metabolism, oxidative phosphorylation, cardiac contraction and morphogenesis, phospholipid metabolism and calcineurin signaling; increasing proteolysis and negative control of MAPK; and mixed changes in nuclear transport and angiogenic genes. Pathway analysis supports reductions in: autophagy, stress response, ER protein processing, mRNA surveillance and ribosome/translation genes; with later falls in mitochondrial biogenesis, oxidative phosphorylation and proteasome genes in I-R hearts. Summarizing, early cardiac aging is evident from 16 to 32 wks in male mice, characterized by: declining cardiovascular reserve and stress-resistance, transcriptomic evidence of constitutive stress and altered catecholamine and survival/growth signaling in healthy hearts; and declining stress response, quality control, mitochondrial energy metabolism and cardiac modeling processes in stressed hearts. These very early changes, potentially key substrate for advanced aging, may inform approaches to healthy aging and cardioprotection in the adult heart.

New insights of necroptosis and immune infiltration in sepsis-induced myocardial dysfunction from bioinformatics analysis through RNA-seq in mice

Sepsis is a life-threatening organ dysfunction caused by dysregulated host immune response to infection. Sepsis-induced myocardial dysfunction (SIMD) is a common complication in patients with severe sepsis and is associated with increased mortality. The molecular mechanisms underlying SIMD are complex and not well characterized. Excessive inflammation due to impaired regulation of immune response is one of the major causes of SIMD. Necroptosis is a novel type of cell death that is closely related to tissue injury and inflammation. However, the role of necroptosis in SIMD is not known. Therefore, in this study, we performed an in-depth bioinformatics analysis to investigate the relationship between necroptosis and SIMD using a mouse model generated by intraperitoneal injection of lipopolysaccharide (LPS) and the underlying mechanisms. Myocardial function was assessed by echocardiography. Histopathological changes in SIMD were analyzed by hematoxylin and eosin (H&E) staining. Gene expression profiles of the heart tissues from the SIMD and control mice were analyzed by bioinformatics analysis. Transcriptome sequencing demonstrated significant differences in the expression levels of 3654 genes in the heart tissues of SIMD mice including 1810 up-regulated and 1844 down-regulated genes. The necroptosis pathway genes were significantly enriched in the heart tissues from the SIMD group mice. We identified 35 necroptosis-related differentially expressed genes (NRDEGs) including MLKL and RIPK3. Cardiomyocyte necroptosis was confirmed by qRT-PCR and western blot analysis. The expression levels of most NRDEGs showed positive correlation with the infiltration levels of mast cells, macrophages, and neutrophils, and negative correlation with the infiltration levels of B cells and plasma cells in the heart tissues of the SIMD group mice. In conclusion, this study demonstrated that necroptosis was associated with changes in the infiltration levels of several immune cell types in the heart tissues of the SIMD model mice. This suggested that necroptosis influenced SIMD development by modulating the immune microenvironment. This suggested that NRDEGs are potential diagnostic biomarkers and therapeutic targets for patients with SIMD.

Identification of PIK3CG as a hub in septic myocardial injury using network pharmacology and weighted gene co-expression network analysis

Sepsis causes multiple organ injuries, among which the heart is one most severely damaged organ. Melatonin (MEL) alleviates septic myocardial injury, although a systematic and comprehensive approach is still lacking to understand the precise protective machinery of MEL. This study aimed to examine the underlying mechanisms of MEL on improvement of septic myocardial injury at a systematic level. This study integrated three analytic modalities including database investigations, RNA-seq analysis, and weighted gene co-expression network analysis (WCGNA), in order to acquire a set of genes associated with the pathogenesis of sepsis. The Drugbank database was employed to predict genes that may serve as pharmacological targets for MEL-elicited benefits, if any. A pharmacological protein-protein interaction network was subsequently constructed, and 66 hub genes were captured which were enriched in a variety of immune response pathways. Notably, PIK3CG, one of the hub genes, displayed high topological characteristic values, strongly suggesting its promise as a novel target for MEL-evoked treatment of septic myocardial injury. Importantly, molecular docking simulation experiments as well as in vitro and in vivo studies supported an essential role for PIK3CG in MEL-elicited effect on septic myocardial injury. This study systematically clarified the mechanisms of MEL intervention in septic myocardial injury involved multiple targets and multiple pathways. Moreover, PIK3CG-governed signaling cascade plays an important role in the etiology of sepsis and septic myocardial injury. Findings from our study provide valuable information on novel intervention targets for the management of septic myocardial injury. More importantly, this study has indicated the utility of combining a series of techniques for disease target discovery and exploration of possible drug targets, which should shed some light on elucidation of experimental and clinical drug action mechanisms systematically.

Time Series Transcriptomic Analysis by RNA Sequencing Reveals a Key Role of PI3K in Sepsis-Induced Myocardial Injury in Mice

Septic cardiomyopathy is the main complication and cause of death of severe sepsis with limited therapeutic strategy. However, the molecular mechanism of sepsis-induced cardiac injury remains unclear. The present study was designed to investigate differentially expressed genes (DEGs) involved in the pathogenesis of septic cardiomyopathy induced by cecal ligation and puncture (CLP) in mice. Male C57BL/6J mice (8-10 weeks old) were subjected to CLP with 21-gauge needles for 24, 48, and 72 h. Myocardial function was assessed by echocardiography. The pathological changes of the heart were evaluated by hematoxylin and eosin as well as immunohistochemical staining. Time series RNA sequencing was utilized to investigate the gene expression profiles. CLP surgery resulted in a significant decrease of animal survival rate and left ventricle contractile function, and an increase in cardiac dilation and infiltration of proinflammatory cells including Mac-2⁺ macrophages in a time-dependent manner. RNA sequencing identified 5,607 DEGs in septic myocardium at 24, 48, and 72 h after CLP operation. Moreover, gene ontology analysis revealed that these DEGs were mainly associated with the biological processes, including cell adhesion, immune system process, inflammatory response, and positive regulation of cell migration. KEGG pathway enrichment analysis indicated that Staphylococcus aureus infection, osteoclast differentiation, leishmaniasis, and ECM-receptor interaction were significantly altered in septic hearts. Notably, Pik3r1 and Pik3r5 were localized in the center of the gene co-expression network, and were markedly upregulated in CLP-induced septic myocardium. Further, blocking PI3Kγ by the specific inhibitor CZC24832 significantly protected against sepsis-induced cardiac impairment. The present study uncovers the gene expression signatures of CLP-induced myocardial injury and sheds light on the role of Pik3r5 in septic cardiomyopathy.

Adenosine A2a Receptor Regulates Autophagy Flux and Apoptosis to Alleviate Ischemia-Reperfusion Injury via the cAMP/PKA Signaling Pathway

Exploring effective methods to lessen myocardial ischemia-reperfusion injury still has positive significance. The adenosine A2a receptor (A2aR) has played a crucial part in cardiac ischemia-reperfusion injury. Previous studies revealed that the adenosine A2a receptor regulated autophagy, but the specific mechanism in myocardial ischemia-reperfusion injury was still unclear. We established an ischemia-reperfusion model (30 min of ischemia and 2 h of reperfusion) in vivo and a model with oxygen-glucose deprivation for 6 h and reoxygenation for 18 h (OGDR) in vitro. The ischemia-reperfusion injury resulted in prolonged QTc interval, left ventricular systolic dysfunction, and myocardial infarction. In vitro model, we found that the OGDR-induced autophagosomes and apoptosis caused myocardial cell death, as evidenced by a significant increase in the generation of lactate dehydrogenase and creatine kinase-MB. Furthermore, overactivated autophagy with rapamycin showed an anti-apoptotic effect. The interaction between autophagy and apoptosis in myocardial ischemia-reperfusion injury was complex and variable. We discovered that the activation of adenosine A2a receptor could promote the expression of Bcl-2 to inhibit the levels of Beclin-1 and LC3II. The number of autophagosomes exceeded that of autolysosomes under OGDR, but the result reversed after A2aR activation. Activated A2aR with its agonist CGS21680 before reperfusion saved cellular survival through anti-apoptosis and anti-autophagy effect, thus improving ventricular contraction disorders, and visibly reducing myocardial infarction size. The myocardial protection of adenosine A2a receptor after ischemia may involve the cAMP-PKA signaling pathway and the interaction of Bcl-2-Beclin-1.

Exploration and validation of hub genes and pathways in the progression of hypoplastic left heart syndrome via weighted gene co-expression network analysis

Background

Despite significant progress in surgical treatment of hypoplastic left heart syndrome (HLHS), its mortality and morbidity are still high. Little is known about the molecular abnormalities of the syndrome. In this study, we aimed to probe into hub genes and key pathways in the progression of the syndrome.

Methods

Differentially expressed genes (DEGs) were identified in left ventricle (LV) or right ventricle (RV) tissues between HLHS and controls using the GSE77798 dataset. Then, weighted gene co-expression network analysis (WGCNA) was performed and key modules were constructed for HLHS. Based on the genes in the key modules, protein–protein interaction networks were conducted, and hub genes and key pathways were screened. Finally, the GSE23959 dataset was used to validate hub genes between HLHS and controls.

Results

We identified 88 and 41 DEGs in LV and RV tissues between HLHS and controls, respectively. DEGs in LV tissues of HLHS were distinctly involved in heart development, apoptotic signaling pathway and ECM receptor interaction. DEGs in RV tissues of HLHS were mainly enriched in BMP signaling pathway, regulation of cell development and regulation of blood pressure. A total of 16 co-expression network were constructed. Among them, black module (r = 0.79 and p value = 2e−04) and pink module (r = 0.84 and p value = 4e−05) had the most significant correlation with HLHS, indicating that the two modules could be the most relevant for HLHS progression. We identified five hub genes in the black module (including Fbn1, Itga8, Itga11, Itgb5 and Thbs2), and five hub genes (including Cblb, Ccl2, Edn1, Itgb3 and Map2k1) in the pink module for HLHS. Their abnormal expression was verified in the GSE23959 dataset.

Conclusions

Our findings revealed hub genes and key pathways for HLHS through WGCNA, which could play key roles in the molecular mechanism of HLHS.

Role of Cardiac A2A Receptors Under Normal and Pathophysiological Conditions

This review presents an overview of cardiac A2A-adenosine receptors The localization of A2A-AR in the various cell types that encompass the heart and the role they play in force regulation in various mammalian species are depicted. The putative signal transduction systems of A2A-AR in cells in the living heart, as well as the known interactions of A2A-AR with membrane-bound receptors, will be addressed. The possible role that the receptors play in some relevant cardiac pathologies, such as persistent or transient ischemia, hypoxia, sepsis, hypertension, cardiac hypertrophy, and arrhythmias, will be reviewed. Moreover, the cardiac utility of A2A-AR as therapeutic targets for agonistic and antagonistic drugs will be discussed. Gaps in our knowledge about the cardiac function of A2A-AR and future research needs will be identified and formulated.

Ammonia inhalation-induced inflammation and structural impairment in the bursa of fabricius and thymus of broilers through NF-κB signaling pathway

Ammonia (NH₃) is a toxic, environmental pollutant, and irritant gas. Previous studies reported the toxic effects of NH₃ which led to inflammation in various organs of chicken. However, the exact mechanism of NH₃-induced inflammation in chicken lymphoid organs bursa of fabricius (BF) and thymus is still elusive. Thus, this study was designed to investigate NH₃-induced inflammation in chicken BF and thymus. Experimental chickens were divided into low (5.0 mg/m³), middle (10.0-15.0 mg/m³), and high (20.0-45.0 mg/m³) NH₃-treated groups. To investigate NH₃-induced inflammation in chicken's BF and thymus, histological observation, NO content and iNOS activity, inflammatory cytokine contents, and mRNA levels were performed by light microscopy, microplate spectrophotometer, ELISA assay, and qRT-PCR. The finding of the present study showed that NH₃ exposure reduced BF and thymus index, increased nitric oxide (NO) content and inducible nitric oxide synthase (iNOS) activity, inflammatory cytokine contents and mRNA levels of nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (Cox-2), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-10, IL-1β, IL-18, toll-like receptor 2A (TLR-2A), and iNOS. Histopathological examination revealed signs of inflammation including increased nuclear debris and vacuoles in the cortex and medulla of thymus and bursal follicles. Conclusively, our findings displayed that NH₃ exposure affects the normal function of BF and thymus and led inflammation. The data provided a new ground for NH₃-induced toxicity and risk assessment in chicken production.

H2S induces Th1/Th2 imbalance with triggered NF-κB pathway to exacerbate LPS-induce chicken pneumonia response

H₂S is one of the air pollutants, which can cause multiple organ damage to the body. H₂S exposure will directly damage respiratory system and cause inflammatory reaction. In this experiment, the effect of H₂S on LPS-induce chicken pneumonia is explored from the Th1/Th2 balance and the NF-κB pathway. 42-day-old broilers was selected as research object, exposed to exogenous H₂S, received an intraperitoneal injection of LPS to establish inflammatory model on forty-second days. We carry out qRT-PCR and Western blot to detect the expression of cytokines secreted by Th1/Th2, PPAR-γ/HO-1 genes, NF-κB pathway genes and the downstream genes COX-2 and iNOS. We found the expression of IL-4, IL-6, TNF-α and IL-1β increased and that of IFN-γ decreased, which indicating the immune imbalance of Th1/Th2 was occurred and the level of PPAR-γ/HO-1 was significantly suppressed. In addition, the activation of I-κB-β and NF-κB genes with the degradation of I-κB-α indicated that NF-κB pathway has been activated, which accompanied with COX-2, PGE and iNOS increasing. These results suggested that H₂S exposure can lead to Th1/Th2 immune imbalance, repress the anti-inflammatory effect of PPAR-γ/HO-1, and then activate NF-κB pathway-related genes and the downstream genes to aggravate pneumonia induced by LPS.

Phenotyping of Mice with Heart Specific Overexpression of A2A-Adenosine Receptors: Evidence for Cardioprotective Effects of A2A-Adenosine Receptors

Background: Adenosine can be produced in the heart and acts on cardiac adenosine receptors. One of these receptors is the A_2A-adenosine receptor (A_2A-AR).

Methods and Results: To better understand its role in cardiac function, we generated and characterized mice (A_2A-TG) which overexpress the human A_2A-AR in cardiomyocytes. In isolated atrial preparations from A_2A-TG but not from WT, CGS 21680, an A_2A-AR agonist, exerted positive inotropic and chronotropic effects. In ventricular preparations from A_2A-TG but not WT, CGS 21680 increased the cAMP content and the phosphorylation state of phospholamban and of the inhibitory subunit of troponin in A_2A-TG but not WT. Protein expression of phospholamban, SERCA, triadin, and junctin was unchanged in A_2A-TG compared to WT. Protein expression of the α-subunit of the stimulatory G-protein was lower in A_2A-TG than in WT but expression of the α-subunit of the inhibitory G-protein was higher in A_2A-TG than in WT. While basal hemodynamic parameters like left intraventricular pressure and echocardiographic parameters like the systolic diameter of the interventricular septum were higher in A_2A-TG than in WT, after β-adrenergic stimulation these differences disappeared. Interestingly, A_2A-TG hearts sustained global ischemia better than WT.

Conclusion: We have successfully generated transgenic mice with cardiospecific overexpression of a functional A_2A-AR. This receptor is able to increase cardiac function per se and after receptor stimulation. It is speculated that this receptor may be useful to sustain contractility in failing human hearts and upon ischemia and reperfusion.