M3-mAChR Stimulation Exerts Anti-apoptotic Effect Via Activating the HIF-1α/HO-1/VEGF Signaling Pathway in H9c2 Rat Ventricular Cells:

The Role of Muscarinic Acetylcholine Receptor M3 in Cardiovascular Diseases

The muscarinic acetylcholine receptor M3 (M3-mAChR) is involved in various physiological and pathological processes. Owing to specific cardioprotective effects, M3-mAChR is an ideal diagnostic and therapeutic biomarker for cardiovascular diseases (CVDs). Growing evidence has linked M3-mAChR to the development of multiple CVDs, in which it plays a role in cardiac protection such as anti-arrhythmia, anti-hypertrophy, and anti-fibrosis. This review summarizes M3-mAChR's expression patterns, functions, and underlying mechanisms of action in CVDs, especially in ischemia/reperfusion injury, cardiac hypertrophy, and heart failure, opening up a new research direction for the treatment of CVDs.

The prognostic and therapeutic potential of HO-1 in leukemia and MDS

BACKGROUND

Heme oxygenase-1 (HO-1), a heme-degrading enzyme, is proven to have anti-apoptotic effects in several malignancies. In addition, HO-1 is reported to cause chemoresistance and increase cell survival. Growing evidence indicates that HO-1 contributes to the course of hematological malignancies as well. Here, the expression pattern, prognostic value, and the effect of HO-1 targeting in HMs are discussed.

MAIN BODY

According to the recent literature, it was discovered that HO-1 is overexpressed in myelodysplastic syndromes (MDS), chronic myeloid leukemia (CML), acute myeloblastic leukemia (AML), and acute lymphoblastic leukemia (ALL) cells and is associated with high-risk disease. Furthermore, in addition to HO-1 expression by leukemic and MDS cells, CML, AML, and ALL leukemic stem cells express this protein as well, making it a potential target for eliminating minimal residual disease (MRD). Moreover, it was concluded that HO-1 induces tumor progression and prevents apoptosis through various pathways.

CONCLUSION

HO-1 has great potential in determining the prognosis of leukemia and MDS patients. HO-1 induces resistance to several chemotherapeutic agents as well as tyrosine kinase inhibitors and following its inhibition, chemo-sensitivity increases. Moreover, the exact role of HO-1 in Chronic Lymphocytic Leukemia (CLL) is yet unknown. While findings illustrate that MDS and other leukemic patients could benefit from HO-1 targeting. Future studies can help broaden our knowledge regarding the role of HO-1 in MDS and leukemia. Video abstract.

Isoflurane‑induced postoperative cognitive dysfunction is mediated by hypoxia‑inducible factor‑1α‑dependent neuroinflammation in aged rats

Elderly patients are at high risk of developing postoperative cognitive dysfunction (POCD) after prolonged exposure to inhaled anesthetics. However, the pathogenesis of POCD remains unknown. Hypoxia-inducible factor-1α (HIF-1α) is activated by inhaled anesthetics. The aim of the present study was to determine the role of HIF-1α in isoflurane-induced neuroinflammation and the resulting cognitive impairment. Following a 4-h exposure to 1.5% isoflurane in 20-month-old rats, increased expression of HIF-1α protein, activation of nuclear factor (NF)-κB signaling and increased expression of TNF-1α were observed in the hippocampus of isoflurane-exposed rats compared with the control group. Pharmacological inhibition of HIF-1α activation by 5-[1-(phenylmethyl)-1H-indazol-3-yl]-2-furanmethanol (YC-1) markedly suppressed the enhanced expression of HIF-1α, disrupted NF-κB signaling pathway activity and inhibited the isoflurane-induced increase of TNF-1α expression. YC-1 pretreatment also significantly attenuated isoflurane-induced cognitive deficits according to the results of the Morris water maze task. These results suggest that hippocampal HIF-1α appears to be involved in an upstream mechanism of isoflurane-induced cognitive impairment. Further research is warranted to fully clarify the pathogenesis and investigate HIF-1α as a potential therapeutic target for POCD.

Herb pair Danggui-Honghua: mechanisms underlying blood stasis syndrome by system pharmacology approach

Herb pair Danggui-Honghua has been frequently used for treatment of blood stasis syndrome (BSS) in China, one of the most common clinical pathological syndromes in traditional Chinese medicine (TCM). However, its therapeutic mechanism has not been clearly elucidated. In the present study, a feasible system pharmacology model based on chemical, pharmacokinetic and pharmacological data was developed via network construction approach to clarify the mechanisms of this herb pair. Thirty-one active ingredients of Danggui-Honghua possessing favorable pharmacokinetic profiles and biological activities were selected, interacting with 42 BSS-related targets to provide potential synergistic therapeutic actions. Systematic analysis of the constructed networks revealed that these targets such as HMOX1, NOS2, NOS3, HIF1A and PTGS2 were mainly involved in TNF signaling pathway, HIF-1 signaling pathway, estrogen signaling pathway and neurotrophin signaling pathway. The contribution index of every active ingredient also indicated six compounds, including hydroxysafflor yellow A, safflor yellow A, safflor yellow B, Z-ligustilide, ferulic acid, and Z-butylidenephthalide, as the principal components of this herb pair. These results successfully explained the polypharmcological mechanisms underlying the efficiency of Danggui-Honghua for BSS treatment, and also probed into the potential novel therapeutic strategies for BSS in TCM.

Effects of Nuclear Factor-E2-related factor 2/Heme Oxygenase 1 on splanchnic hemodynamics in experimental cirrhosis with portal hypertension

OBJECTIVE

We explored the effects of Nuclear Factor-E2-related factor 2 (Nrf2) and Heme Oxygenase 1 (HO-1) on splanchnic hemodynamics in portal hypertensive rats.

METHODS

Experimental cirrhosis with portal hypertension was induced by intraperitoneal injection of carbon tetrachloride. The expression of proteins was examined by immunoblotting. Hemodynamic studies were performed by radioactive microspheres. The vascular perfusion system was used to measure the contractile response of mesentery arterioles in rats.

RESULTS

Nrf2 expression in the nucleus and HO-1 expression in cytoplasm was significantly enhanced in portal hypertensive rats. Portal pressure, as well as regional blood flow, increased significantly in portal hypertension and can be blocked by tin protoporphyrin IX. The expression of endogenous nitric oxide synthase and vascular endothelial growth factors increased significantly compared to normal rats, while HO-1 inhibition decreased the expression of these proteins significantly. The contractile response of mesenteric arteries decreased in portal hypertension, but can be partially recovered through tin protoporphyrin IX treatment.

CONCLUSIONS

The expression of Nrf2/HO-1 increased in mesenteric arteries of portal hypertensive rats, which was related to oxidative stress. HO-1was involved in increased portal pressure and anomaly splanchnic hemodynamics in portal hypertensive rats.

Targeting the ROS-HIF-1-endothelin axis as a therapeutic approach for the treatment of obstructive sleep apnea-related cardiovascular complications

Obstructive sleep apnea (OSA) is now recognized as an independent and important risk factor for cardiovascular diseases such as hypertension, coronary heart disease, heart failure and stroke. Clinical and experimental data have confirmed that intermittent hypoxia is a major contributor to these deleterious consequences. The repetitive occurrence of hypoxia-reoxygenation sequences generates significant amounts of free radicals, particularly in moderate to severe OSA patients. Moreover, in addition to hypoxia, reactive oxygen species (ROS) are potential inducers of the hypoxia inducible transcription factor-1 (HIF-1) that promotes the transcription of numerous adaptive genes some of which being deleterious for the cardiovascular system, such as the endothelin-1 gene. This review will focus on the involvement of the ROS-HIF-1-endothelin signaling pathway in OSA and intermittent hypoxia and discuss current and potential therapeutic approaches targeting this pathway to treat or prevent cardiovascular disease in moderate to severe OSA patients.

Effect of the M1 Muscarinic Acetylcholine Receptor on Retinal Neuron Number Studied with Gene-Targeted Mice

Pharmacological activation of the M1 muscarinic receptor subtype was suggested to promote the survival of retinal neurons. We examined the hypothesis that the M1 receptor is crucial for retinal neuron survival in vivo by using mice devoid of the M1 receptor gene. Muscarinic receptor gene expression was determined in the retina using real-time PCR. The amount of neurons in the retinal ganglion cell layer and of axons in the optic nerve was determined in retinal wholemounts stained with cresyl blue and in optic nerve cross-sections stained with toluidine blue, respectively. mRNA of all five muscarinic receptor subtypes (M1-M5) was detected in the retina from wild-type mice. Remarkably, M2 and M3 receptor mRNA were most abundant. In retinas from M1 receptor-deficient mice, M4 receptor mRNA expression was increased compared to that of wild-type mice, while no marked changes in the mRNA expression levels of the other muscarinic receptor subtypes were observed. The amount of cells in the retinal ganglion cell layer and the amount of axons in the optic nerve did not differ between M1 receptor-deficient and wild-type mice. The present findings suggest that the M1 receptor is not essential for the survival of retinal neurons in vivo.

Heme oxygenase-1 plays a crucial role in chemoresistance in acute myeloid leukemia

OBJECTIVES

The heme oxygenase-1 (HO-1) gene may contribute to the development of acquired chemoresistance in solid tumor cells, but its function in acute myeloid leukemia (AML) remains unclear. Therefore, we investigated whether the expressions of HO-1 mRNA and protein were associated with AML chemoresistance.

METHODS

Bone marrow or peripheral blood was obtained from newly diagnosed (n = 26), relapsed (n = 10), and completely remitted (n = 18) patients with AML (M3 exclusion) and healthy donors (n = 10). Small interfering RNA was used to stably silence HO-1 gene expression in AML cell lines. The expressions of HO-1, hypoxia inducible factor-1ɑ (HIF-1ɑ), glucose transporter-1 (GLUT1) mRNA and proteins were measured by quantitative real-time PCR and Western blot. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction was analyzed by flow cytometry.

RESULTS

The drug-resistant AML cell line HL-60R was significantly less sensitive to cytarabine and daunorubicin than HL-60 cells. HO-1 mRNA and proteins were highly expressed in HL-60R cells. However, down-regulating HO-1 significantly enhanced the sensitivity of HL-60R to chemotherapy, and the expressions of HIF-1ɑ and GLUT1 mRNA and proteins decreased. Meanwhile, the expressions of caspase-3 and caspase-8 proteins increased, while that of bcl-2 decreased. Overexpressions of HO-1, HIF-1ɑ, and GLUT1 were associated with poor response of AML to chemotherapy. Conclusions Overexpressions of HO-1, HIF-1ɑ, and GLUT1 might be involved in the chemoresistance of AML. HO-1 is a potential target to overcome the drug resistance of AML.

Hydrogen gas protects against serum and glucose deprivation‑induced myocardial injury in H9c2 cells through activation of the NF‑E2‑related factor 2/heme oxygenase 1 signaling pathway

Ischemia or hypoxia‑induced myocardial injury is closely associated with oxidative stress. Scavenging free radicals and/or enhancing endogenous antioxidative defense systems may be beneficial for the impediment of myocardial ischemic injury. Hydrogen (H2) gas, as a water‑ and lipid‑soluble small molecule, is not only able to selectively eliminate hydroxyl (·OH) free radicals, but also to enhance endogenous antioxidative defense systems in rat lungs and arabidopsis plants. However, thus far, it has remained elusive whether H2 gas protects cardiomyocytes through enhancement of endogenous antioxidative defense systems. In the present study, the cardioprotective effect of H2 gas against ischemic or hypoxic injury was investigated, along with the underlying molecular mechanisms. H9c2 cardiomyoblasts (H9c2 cells) were treated in vitro with a chemical hypoxia inducer, cobalt chloride (CoCl2), to imitate hypoxia, or by serum and glucose deprivation (SGD) to imitate ischemia. Cell viability and intracellular ·OH free radicals were assessed. The role of an endogenous antioxidative defense system, the NF‑E2‑related factor 2 (Nrf2)/heme oxygenase 1 (HO‑1) signaling pathway, was evaluated. The findings revealed that treatment with CoCl2 or SGD markedly reduced cell viability in H9c2 cells. H2 gas‑rich medium protected against cell injury induced by SGD, but not that induced by CoCl2. When the cells were exposed to SGD, levels of intracellular ·OH free radicals were markedly increased; this was mitigated by H2 gas‑rich medium. Exposure of the cells to SGD also resulted in significant increases in HO‑1 expression and nuclear Nrf2 levels, and the HO‑1 inhibitor ZnPP IX and the Nrf2 inhibitor brusatol aggravated SGD‑induced cellular injury. H2 gas‑rich medium enhanced SGD‑induced upregulation of HO‑1 and Nrf2, and the HO‑1 or Nrf2 inhibition partially suppressed H2 gas‑induced cardioprotection. Furthermore, following genetic silencing of Nrf2 by RNA interference, the effects of H2 gas on the induction of HO‑1 and cardioprotection were markedly reduced. In conclusion, H2 gas protected cardiomyocytes from ischemia‑induced myocardial injury through elimination of ·OH free radicals and also through activation of the Nrf2/HO‑1 signaling pathway.

Silver nanoparticles induce anti-proliferative effects on airway smooth muscle cells. Role of nitric oxide and muscarinic receptor signaling pathway

Silver nanoparticles (AgNPs) are used to manufacture materials with new properties and functions. However, little is known about their toxic or beneficial effects on human health, especially in the respiratory system, where its smooth muscle (ASM) regulates the airway contractility by different mediators, such as acetylcholine (ACh) and nitric oxide (NO). The aim of this study was to evaluate the effects of AgNPs on ASM cells. Exposure to AgNPs induced ACh-independent expression of the inducible nitric oxide synthase (iNOS) at 100 μg/mL, associated with excessive production of NO. AgNPs induced the muscarinic receptor activation, since its blockage with atropine and blockage of its downstream signaling pathway inhibited the NO production. AgNPs at 10 and 100 μg/mL induced ACh-independent prolonged cytotoxicity and decreased cellular proliferation mediated by the muscarinic receptor-iNOS pathway. However, the concentration of 100 μg/mL of AgNPs induced muscarinic receptor-independent apoptosis, suggesting the activation of multiple pathways. These data indicate that AgNPs induce prolonged cytotoxic and anti-proliferative effects on ASM cells, suggesting an activation of the muscarinic receptor-iNOS pathway. Further investigation is required to understand the full mechanisms of action of AgNPs on ASM under specific biological conditions.

Heme oxygenase-1 prevents cardiac dysfunction in streptozotocin-diabetic mice by reducing inflammation, oxidative stress, apoptosis and enhancing autophagy

Heme oxygenase-1 (HO-1) has been implicated in cardiac dysfunction, oxidative stress, inflammation, apoptosis and autophagy associated with heart failure, and atherosclerosis, in addition to its recognized role in metabolic syndrome and diabetes. Numerous studies have presented contradictory findings about the role of HO-1 in diabetic cardiomyopathy (DCM). In this study, we explored the role of HO-1 in myocardial dysfunction, myofibril structure, oxidative stress, inflammation, apoptosis and autophagy using a streptozotocin (STZ)-induced diabetes model in mice systemically overexpressing HO-1 (Tg-HO-1) or mutant HO-1 (Tg-mutHO-1). The diabetic mouse model was induced by multiple peritoneal injections of STZ. Two months after injection, left ventricular (LV) function was measured by echocardiography. In addition, molecular biomarkers related to oxidative stress, inflammation, apoptosis and autophagy were evaluated using classical molecular biological/biochemical techniques. Mice with DCM exhibited severe LV dysfunction, myofibril structure disarray, aberrant cardiac oxidative stress, inflammation, apoptosis, autophagy and increased levels of HO-1. In addition, we determined that systemic overexpression of HO-1 ameliorated left ventricular dysfunction, myofibril structure disarray, oxidative stress, inflammation, apoptosis and autophagy in DCM mice. Furthermore, serine/threonine-specific protein kinase (Akt) and AMP-activated protein kinase (AMPK) phosphorylation is normally inhibited in DCM, but overexpression of the HO-1 gene restored the phosphorylation of these kinases to normal levels. In contrast, the functions of HO-1 in DCM were significantly reversed by overexpression of mutant HO-1. This study underlines the unique roles of HO-1, including the inhibition of oxidative stress, inflammation and apoptosis and the enhancement of autophagy, in the pathogenesis of DCM.