Calpain-1 mediates vascular remodelling and fibrosis via HIF-1α in hypoxia-induced pulmonary hypertension

Animal models of pulmonary arterial hypertension associated with atrial septal defect

Pulmonary arterial hypertension (PAH) is a well-known complication of congenital heart disease (CHD). The lack of a satisfactory animal model for PAH associated with CHD (PAH-CHD) has limited progress in understanding the pathogenesis of PAH and the development of therapeutic agents. The development of a rat model for PAH associated with atrial septal defect (ASD) was achieved through atrial septal puncture and thermal ablation. Two and 4 weeks after modeling, hematoxylin and eosin staining showed that the vascular thickness, vascular thickness index, vascular area, and vascular area index in pulmonary arteries with an outer diameter of 50-300 μm in the PAH-ASD 2 and 4 weeks group were higher than those in the sham group (all P < 0.05). Alpha-smooth muscle actin (ɑ-SMA) staining showed that the medial thickness, medial thickness index, medial area, and medial area index in pulmonary arteries with an outer diameter of 50-300 µm at 2 and 4 weeks after modeling were significantly higher than those in the sham group (all P < 0.05). Additionally, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in the PAH-ASD 2 and 4 weeks groups were significantly higher than those in the sham group (both P < 0.05). Elastin van Gieson staining showed that the vascular obstruction score in the PAH-ASD 2 and 4 weeks group was significantly higher than that in the sham group (both P < 0.05). The PAH-ASD rats were successfully generated. These findings suggest that our model would be useful for further research into the pathogenesis, prevention, and treatment of PAH-ASD.

Changes in PI3K/AKT and NRF2/HO-1 signaling expression and intestinal microbiota in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is the outcome of the prolonged interstitial pneumonia, characterized by excessive accumulation of fibroblasts and collagen deposition, leading to its development. This study aimed to study the changes in PI3K/AKT and NRF2/HO-1 signaling expression and intestinal microbiota in a rat model of a novel bleomycin-induced pulmonary fibrosis. The findings of our study showed the model was successfully established. The results showed that the alveolar septum in the model was significantly widened and infiltrated by severe inflammatory cells. Alveolar atrophy occurred due to the formation of multiple inflammatory foci. During this period, fibrous tissue was distributed in strips and patches, primarily around the pulmonary interstitium and bronchus. Moreover, lung damage and fibrosis progressively worsened over time. The mRNA expression of HO-1 and NRF2 in the model decreased while the mRNA expression of HIF-1α, VEGF, PI3K and AKT increased. Furthermore, it was observed to decrease the protein expression of E-cad, HO-1 and NRF2, and increase the protein expression of α-SMA and p-AKT. Additionally, this model leaded to an imbalance in the intestinal microbiota. This study demonstrate that the novel pulmonary fibrosis model activates the NRF2/HO-1 pathway and the PI3K/AKT pathway in rat lung tissues, and leading to intestinal barrier disorder.

Ginsenoside Rg1 alleviates vascular remodeling in hypoxia-induced pulmonary hypertension mice through the calpain-1/STAT3 signaling pathway

Background

Hypoxic pulmonary hypertension (HPH) is the main pathological change in vascular remodeling, a complex cardiopulmonary disease caused by hypoxia. Some research results have shown that ginsenoside Rg1 (Rg1) can improve vascular remodeling, but the effect and mechanism of Rg1 on hypoxia-induced pulmonary hypertension are not clear. The purpose of this study was to discuss the potential mechanism of action of Rg1 on HPH.

Methods

C57BL/6 mice, calpain-1 knockout mice and Pulmonary artery smooth muscle cells (PASMCs) were exposed to a low oxygen environment with or without different treatments. The effect of Rg1 and calpain-1 silencing on inflammation, fibrosis, proliferation and the protein expression levels of calpain-1, STAT3 and p-STAT3 were determined at the animal and cellular levels.

Results

At the mouse and cellular levels, hypoxia promotes inflammation, fibrosis, and cell proliferation, and the expression of calpain-1 and p-STAT3 is also increased. Ginsenoside Rg1 administration and calpain-1 knockdown, MDL-28170, and HY-13818 treatment showed protective effects on hypoxia-induced inflammation, fibrosis, and cell proliferation, which may be associated with the downregulation of calpain-1 and p-STAT3 expression in mice and cells. In addition, overexpression of calpain 1 increased p-STAT3 expression, accelerating the onset of inflammation, fibrosis and cell proliferation in hypoxic PASMCs.

Conclusion

Ginsenoside Rg1 may ameliorate hypoxia-induced pulmonary vascular remodeling by suppressing the calpain-1/STAT3 signaling pathway.

Otud6b induces pulmonary arterial hypertension by mediating the Calpain-1/HIF-1α signaling pathway

Pulmonary hypertension (PAH) is a cardiopulmonary disease in which pulmonary artery pressure continues to rise, leading to right heart failure and death. Otud6b is a member of the ubiquitin family and is involved in cell proliferation, apoptosis and inflammation. The aim of this study was to understand the role and mechanism of Otud6b in PAH. C57BL/6 and Calpain-1 knockout (KO) mice were exposed to a PAH model induced by 10% oxygen. Human pulmonary artery endothelial cells (HPACEs) and human pulmonary artery smooth muscle cells (HPASMCs) were exposed to 3% oxygen to establish an in vitro model. Proteomics was used to determine the role of Otud6b and its relationship to Calpain-1/HIF-1α signaling. The increased expression of Otud6b is associated with the progression of PAH. ROtud6b activates Otud6b, induces HIF-1α activation, increases the production of ET-1 and VEGF, and further aggravates endothelial injury. Reducing Otud6b expression by tracheal infusion of siOtud6b has the opposite effect, improving hemodynamic and cardiac response to PAH, reducing the release of Calpain-1 and HIF-1α, and eliminating the pro-inflammatory and apoptotic effects of Otud6b. At the same time, we also found that blocking Calpain-1 reduced the effect of Otud6b on HIF-1α, and inhibiting HIF-1α reduced the expression of Calpain-1 and Otud6b. Our study shows that increased Otud6b expression during hypoxia promotes the development of PAH models through a positive feedback loop between HIF-1α and Calpain-1. Therefore, we use Otud6b as a biomarker of PAH severity, and regulating Otud6b expression may be an effective target for the treatment of PAH.

Dissolving microneedles loaded with nimodipine for prevention of sleep disorders at a high altitude

Sleep disorders are one of the most common acute reactions on the plateau, which can cause serious complications. However, there is no effective and safe treatment currently available. Nimodipine (NMD) is a dihydropyridine calcium channel blocker with neuroprotective and vasodilating activity, mainly used for the treatment of ischemic brain injury. Commercial oral or injectable NMD formulations are not a good option for central neuron diseases due to their poor brain delivery. In this study, nimodipine dissolving microneedles (NDMNs) were prepared for the prevention of sleep disorders caused by hypoxia. NDMNs were composed of NMD and polyvinyl pyrrolidone (PVP) K90 with a conical morphology and high rigidity. After administration of NDMNs on the back neck of mice, the concentration of NMD in the brain was significantly higher than that of oral medication as was confirmed by the fluorescent imaging on mouse models. NDMNs enhanced cognitive function, alleviated oxidative stress, and improved the sleep quality of mice with high-altitude sleep disorders. The blockage of calcium ion overloading may be an important modulation mechanism. NDMNs are a promising and user-friendly formulation for the prevention of high-altitude sleep disorders.

OPN silencing reduces hypoxic pulmonary hypertension via PI3K-AKT-induced protective autophagy

Hypoxic pulmonary hypertension (HPH) is a pulmonary vascular disease primarily characterized by progressive pulmonary vascular remodeling in a hypoxic environment, posing a significant clinical challenge. Leveraging data from the Gene Expression Omnibus (GEO) and human autophagy-specific databases, osteopontin (OPN) emerged as a differentially expressed gene, upregulated in cardiovascular diseases such as pulmonary arterial hypertension (PAH). Despite this association, the precise mechanism by which OPN regulates autophagy in HPH remains unclear, prompting the focus of this study. Through biosignature analysis, we observed significant alterations in the PI3K-AKT signaling pathway in PAH-associated autophagy. Subsequently, we utilized an animal model of OPNfl/fl-TAGLN-Cre mice and PASMCs with OPN shRNA to validate these findings. Our results revealed right ventricular hypertrophy and elevated mean pulmonary arterial pressure (mPAP) in hypoxic pulmonary hypertension model mice. Notably, these effects were attenuated in conditionally deleted OPN-knockout mice or OPN-silenced hypoxic PASMCs. Furthermore, hypoxic PASMCs with OPN shRNA exhibited increased autophagy compared to those in hypoxia alone. Consistent findings from in vivo and in vitro experiments indicated that OPN inhibition during hypoxia reduced PI3K expression while increasing LC3B and Beclin1 expression. Similarly, PASMCs exposed to hypoxia and PI3K inhibitors had higher expression levels of LC3B and Beclin1 and suppressed AKT expression. Based on these findings, our study suggests that OPNfl/fl-TAGLN-Cre effectively alleviates HPH, potentially through OPN-mediated inhibition of autophagy, thereby promoting PASMCs proliferation via the PI3K-AKT signaling pathway. Consequently, OPN emerges as a novel therapeutic target for HPH.

Expression and regulation of HIF-1a in hypoxic pulmonary hypertension: Focus on pathological mechanism and Pharmacological Treatment

Hypoxia inducible factor-1(HIF-1), a heterodimeric transcription factor, is composed of two subunits (HIF-1α and HIF-1β). It is considered as an important transcription factor for regulating oxygen changes in hypoxic environment, which can regulate the expression of various hypoxia-related target genes and play a role in acute and chronic hypoxia pulmonary vascular reactions. In this paper, the function and mechanism of HIF-1a expression and regulation in hypoxic pulmonary hypertension (HPH) were reviewed, and current candidate schemes for treating pulmonary hypertension by using HIF-1a as the target were introduced, so as to provide reference for studying the pathogenesis of HPH and screening effective treatment methods.

Baicalin attenuates pulmonary vascular remodeling by inhibiting calpain-1 mediated endothelial-to-mesenchymal transition

Background

Previous studies have demonstrated the beneficial effect of baicalin on pulmonary arterial hypertension (PAH), but the mechanism is unclear.

Aim

The aim of the present study was to evaluate the effect of baicalin on pulmonary vascular remodeling (PVR) with a focus on calpain-1-mediated endothelial-to-mesenchymal transition (EndMT).

Methods

PAH was induced by intraperitoneal injection of monocrotaline (MCT) in rats and hypoxia in calpain-1 gene knockout (Capn1-/-) and wild-type C57BL/6 mice. An in vitro PVR model was established in PASMCs and HPAECs.

Results

The data showed that baicalin treatment and calpain-1 inhibition alleviated MCT and hypoxia-induced increases in right ventricular systolic pressure (RVSP), prevented right ventricle hypertrophy and PVR, and attenuated cardiopulmonary fibrosis. Moreover, baicalin ameliorated PAH-induced EndMT, as evidenced by the suppressed expression of mesenchymal markers vimentin, and α-SMA and restored expression of endothelial markers CD31, and VE-cadherin. In vitro studies showed that baicalin treatment blocked TGF-β1-induced EndMT in HPAECs and abolished hypoxia-induced PASMC proliferation and migration. All the beneficial effects of baicalin on PVR in vitro and in vivo were accompanied by suppressed calpain-1 expression. Further study demonstrated that baicalin treatment and calpain-1 inhibition inhibited the enhanced expression of PI3K and p-AKT both in vitro and in vivo.

Conclusions

In conclusion, baicalin treatment attenuates PVR by inhibiting calpain-1 and PI3K/Akt-mediated EndMT.

Study of Transcriptomic Analysis of Yak (Bos grunniens) and Cattle (Bos taurus) Pulmonary Artery Smooth Muscle Cells under Oxygen Concentration Gradients and Differences in Their Lung Histology and Expression of Pyruvate Dehydrogenase Kinase 1-Related Factors

The aim of this study was to investigate the molecular mechanisms by which hypoxia affects the biological behavior of yak PASMCs, the changes in the histological structure of yak and cattle lungs, and the relationships and regulatory roles that exist regarding the differences in the distribution and expression of PDK1 and its hypoxia-associated factors screened for their role in the adaptation of yak lungs to the plateau hypoxic environment. The results showed that, at the level of transcriptome sequencing, the molecular regulatory mechanisms of the HIF-1 signaling pathway, glucose metabolism pathway, and related factors (HK2/PGK1/ENO1/ENO3/ALDOC/ALDOA) may be closely related to the adaptation of yaks to the hypoxic environment of the plateau; at the tissue level, the presence of filled alveoli and semi-filled alveoli, thicker alveolar septa and basement membranes, a large number of erythrocytes, capillary distribution, and collagen fibers accounted for all levels of fine bronchioles in the lungs of yaks as compared to cattle. A higher percentage of goblet cells was found in the fine bronchioles of yaks, and PDK1, HIF-1α, and VEGF were predominantly distributed and expressed in the monolayers of ciliated columnar epithelium in the branches of the terminal fine bronchioles of yak and cattle lungs, with a small amount of it distributed in the alveolar septa; at the molecular level, the differences in PDK1 mRNA relative expression in the lungs of adult yaks and cattle were not significant (p > 0.05), the differences in HIF-1α and VEGF mRNA relative expression were significant (p < 0.05), and the expression of PDK1 and HIF-1α proteins in adult yaks was stronger than that in adult cattle. PDK1 and HIF-1α proteins were more strongly expressed in adult yaks than in adult cattle, and the difference was highly significant (p < 0.01); the relative expression of VEGF proteins was not significantly different between adult yaks and cattle (p > 0.05). The possible regulatory relationship between the above results and the adaptation of yak lungs to the plateau hypoxic environment paves the way for the regulatory mechanisms of PDK1, HIF-1α, and VEGF, and provides basic information for studying the mechanism of hypoxic adaptation of yaks in the plateau. At the same time, it provides a reference for human hypoxia adaptation and a target for the prevention and treatment of plateau diseases in humans and plateau animals.

Administration of A. muciniphila ameliorates pulmonary arterial hypertension by targeting miR-208a-3p/NOVA1 axis

Pulmonary arterial hypertension (PH) is a chronic disease induced by a progressive increase in pulmonary vascular resistance and failure of the right heart function. A number of studies show that the development of PH is closely related to the gut microbiota, and lung-gut axis might be a potential therapeutic target in the PH treatment. A. muciniphila has been reported to play a critical role in treating cardiovascular disorders. In this study we evaluated the therapeutic effects of A. muciniphila against hypoxia-induced PH and the underlying mechanisms. Mice were pretreated with A. muciniphila suspension (2 × 108 CFU in 200 μL sterile anaerobic PBS, i.g.) every day for 3 weeks, and then exposed to hypoxia (9% O2) for another 4 weeks to induce PH. We showed that A. muciniphila pretreatment significantly facilitated the restoration of the hemodynamics and structure of the cardiopulmonary system, reversed the pathological progression of hypoxia-induced PH. Moreover, A. muciniphila pretreatment significantly modulated the gut microbiota in hypoxia-induced PH mice. miRNA sequencing analysis reveals that miR-208a-3p, a commensal gut bacteria-regulated miRNA, was markedly downregulated in lung tissues exposed to hypoxia, which was restored by A. muciniphila pretreatment. We showed that transfection with miR-208a-3p mimic reversed hypoxia-induced abnormal proliferation of human pulmonary artery smooth muscle cells (hPASMCs) via regulating the cell cycle, whereas knockdown of miR-208a-3p abolished the beneficial effects of A. muciniphila pretreatment in hypoxia-induced PH mice. We demonstrated that miR-208a-3p bound to the 3'-untranslated region of NOVA1 mRNA; the expression of NOVA1 was upregulated in lung tissues exposed to hypoxia, which was reversed by A. muciniphila pretreatment. Furthermore, silencing of NOVA1 reversed hypoxia-induced abnormal proliferation of hPASMCs through cell cycle modulation. Our results demonstrate that A. muciniphila could modulate PH through the miR-208a-3p/NOVA1 axis, providing a new theoretical basis for PH treatment.

Inhibitory Effect of PPARδ Agonist GW501516 on Proliferation of Hypoxia-induced Pulmonary Arterial Smooth Muscle Cells by Regulating the mTOR Pathway

OBJECTIVE

This study aimed to investigate the effects of the peroxisome proliferator-activated receptor δ (PPARδ) agonist GW501516 on the proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by hypoxia, in order to search for new drugs for the treatment and prevention of pulmonary vascular remodeling.

METHODS

PASMCs were incubated with different concentrations of GW501516 (10, 30, 100 nmol/L) under the hypoxic condition. The proliferation was determined by a CCK-8 assay. The cell cycle progression was analyzed by flow cytometry. The expression of PPARδ, S phase kinase-associated protein 2 (Skp2), and cell cycle-dependent kinase inhibitor p27 was detected by Western blotting. Then PASMCs were treated with 100 nmol/ L GW501516, 100 nmol/L mammalian target of rapamycin (mTOR) inhibitor rapamycin and/or 2 µmol/L mTOR activator MHY1485 to explore the molecular mechanisms by which GW501516 reduces the proliferation of PASMCs.

RESULTS

The presented data demonstrated that hypoxia reduced the expression of PPARδ in an oxygen concentration- and time-dependent manner, and GW501516 decreased the proliferation of PASMCs induced by hypoxia by blocking the progression through the G0/G1 to S phase of the cell cycle. In accordance with these findings, GW501516 downregulated Skp2 and upregulated p27 in hypoxia-exposed PASMCs. Further experiments showed that rapamycin had similar effects as GW501516 in inhibiting cell proliferation, arresting the cell cycle, regulating the expression of Skp2 and p27, and inactivating mTOR in hypoxia-exposed PASMCs. Moreover, MHY1485 reversed all the beneficial effects of GW501516 on hypoxia-stimulated PASMCs.

CONCLUSION

GW501516 inhibited the proliferation of PASMCs induced by hypoxia through blocking the mTOR/Skp2/p27 signaling pathway.

Current Advances of Mitochondrial Dysfunction and Cardiovascular Disease and Promising Therapeutic Strategies

Mitochondria are cellular power stations and essential organelles for maintaining cellular homeostasis. Dysfunctional mitochondria have emerged as a key factor in the occurrence and development of cardiovascular disease. This review focuses on advances in the relationship between mitochondrial dysfunction and cardiovascular diseases such as atherosclerosis, heart failure, myocardial ischemia reperfusion injury, and pulmonary arterial hypertension. The clinical value and challenges of mitochondria-targeted strategies, including mitochondria-targeted antioxidants, mitochondrial quality control modulators, mitochondrial function protectors, mitochondrial biogenesis promoters, and recently developed mitochondrial transplants, are also discussed.

Ginsenoside Rg1 attenuates diabetic vascular endothelial dysfunction by inhibiting the calpain-1/ROS/PKC-β axis

AIMS

Vascular endothelial dysfunction (VED) is the onset event of cardiovascular complications in type 2 diabetes mellitus. Ginsenoside Rg1 (Rg1) can improve the cardiovascular system, but its mechanism in diabetic vascular endothelial dysfunction has received little attention.

MAIN METHODS

Male calpain-1-knockout and wild-type C57BL/6 J mice were intraperitoneally injected with streptozotocin and treated with Rg1 (10 and 20 mg/kg) for 8 weeks. Human aortic endothelial cells (HAECs) were incubated with high glucose (HG) and were pretreated with Rg1 (10, 20 μM), MDL-28170 (calpain-1 inhibitor), LY-333531 (PKC-β inhibitor), NAC (ROS inhibitor) and calpain-1 overexpression. Then, factors related to mitochondrial dysfunction, oxidative stress and VED were measured.

KEY FINDINGS

The administration of Rg1 and calpain-1 knockout ameliorated diabetic mitochondrial dysfunction, oxidative stress and VED and inhibited the calpain-1/ROS/PKC-β axis. LY-333531 and NAC treatment restored destructive endothelium-dependent vasodilation in mice with diabetes, while pyrogallol (ROS agonist), PMA (PKC-β agonist) or L-NAME (eNOS inhibitor) treatment abrogated the protective effect of Rg1 against diabetic endothelial dysfunction. The administration of Rg1, MDL-28170, LY-333531 and NAC improved mitochondrial dysfunction, oxidative stress and VED, whereas the overexpression of calpain-1 amplified mitochondrial dysfunction, oxidative stress and VED and further upregulated the expression of PKC-β in HAECs exposed to HG. Overexpression of calpain-1 abrogated the protective effect of Rg1 against HG-induced oxidative stress and VED.

SIGNIFICANCE

These findings reveal that Rg1 can protect against VED by suppressing the calpain-1/ROS/PKC-β axis and alleviating the development of mitochondrial dysfunction and oxidative stress.

A cysteine proteinase inhibitor ALLN alleviates bleomycin-induced skin and lung fibrosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissue disease that is characterized by fibrosis in the skin and internal organs, such as the lungs. Activated differentiation of progenitor cells, which are mainly resident fibroblasts, into myofibroblasts is considered a key mechanism underlying the overproduction of extracellular matrix and the resultant tissue fibrosis in SSc. Calpains are members of the Ca2+-dependent cysteine protease family, whose enzymatic activities participate in signal transduction and tissue remodeling, potentially contributing to fibrosis in various organs. However, the roles of calpain in the pathogenesis of SSc remain unknown. This study aimed to examine the anti-fibrotic properties of N-acetyl-Leu-Leu-norleucinal (ALLN), one of the cysteine proteinase inhibitors that primarily inhibit calpain, in vitro and in vivo, to optimally translate into the therapeutic utility in human SSc.

METHODS

Normal human dermal and lung fibroblasts pretreated with ALLN were stimulated with recombinant transforming growth factor beta 1 (TGF-β1), followed by assessment of TGF-β1/Smad signaling and fibrogenic molecules.

RESULTS

ALLN treatment significantly inhibited TGF-β1-induced phosphorylation and nuclear transport of Smad2/3 in skin and lung fibroblasts. TGF-β1-dependent increases in α-smooth muscle actin (αSMA), collagen type I, fibronectin 1, and some mesenchymal transcription markers were attenuated by ALLN. Moreover, our findings suggest that ALLN inhibits TGF-β1-induced mesenchymal transition in human lung epithelial cells. Consistent with these in vitro findings, administering ALLN (3 mg/kg/day) three times a week intraperitoneally remarkably suppressed the development of skin and lung fibrosis in a SSc mouse model induced by daily subcutaneous bleomycin injection. The number of skin- and lung-infiltrating CD3+ T cells decreased in ALLN-treated mice compared with that in control-treated mice. Phosphorylation of Smad3 and/or an increase in αSMA-positive myofibroblasts was significantly inhibited by ALLN treatment on the skin and lungs. However, no adverse effects were observed.

CONCLUSIONS

Our results prove that calpains can be a novel therapeutic target for skin and lung fibrosis in SSc, considering its inhibitor ALLN.

Calpain Inhibitor Calpeptin Improves Alzheimer's Disease-Like Cognitive Impairments and Pathologies in a Diabetes Mellitus Rat Model

Diabetes mellitus (DM) has been considered an accelerator of Alzheimer's disease (AD), but the cellular and molecular mechanisms underlying this effect are not fully understood. Here, we attempted to determine the role and regulatory mechanism of calpain in the AD-like cognitive decline and pathological changes in rats caused by DM. In the initial stages, our results verified that DM model rats showed cognitive impairment, as well as a loss of neurons, decreased pericyte marker (PDGFR-β and α-SMA), and calpain-2 expression and amyloid-β (Aβ) deposition in the hippocampal tissues. In high glucose-induced primary pericytes, the cell apoptotic rate was increased, and cell proliferation was inhibited in a time-dependent manner. The protein level of calpain-2 was also upregulated by HG induction, but the level of calpain-1 did not change with HG treatment, which was also observed in DM model rats. Subsequently, some DM model rats were administered calpeptin, an inhibitor of calpain. Our data revealed that calpeptin treatment significantly suppressed calpain-1 and calpain-2 expression in the hippocampal tissues and effectively improved the cognitive impairments of DM model rats. Neuronal loss, Aβ accumulation, pericyte loss, inflammation, and oxidative stress injury in the hippocampal tissues of DM model rats were also partly rescued by calpeptin administration. Our work demonstrated that the calpain inhibitor calpeptin could alleviate DM-induced AD-like cognitive impairments and pathological changes in rats, and this effect may be associated with pericytes. Calpeptin may become a promising drug to treat the AD-like complications of DM.

Protective effect of Astragaloside IV on chronic intermittent hypoxia-induced vascular endothelial dysfunction through the calpain-1/SIRT1/AMPK signaling pathway

Vascular endothelial dysfunction (VED) is linked with the pathogenesis of obstructive sleep apnea (OSA) comorbidities, such as cardiovascular disease. Astragaloside IV (As-IV) has exhibited significant improvement for endothelial dysfunction. Nonetheless, the protective mechanism is not clear. Therefore, the present study investigated the potential mechanism of As-IV on VED. Calpain-1 knockout and wild-type C57BL/6 mice exposed to chronic intermittent hypoxia (CIH) were established and treated with As-IV (40, 80 mg/kg) for 4 weeks. Human coronary artery endothelial cells (HCAECs) subjected to CIH exposure were pretreated with As-IV, MDL-28170 (calpain-1 inhibitor) and SRT1720 (SIRT1 activator) for 48 h in vitro. The endothelial function, inflammation, oxidative stress and mitochondrial function were measured to evaluate VED. Our data revealed that As-IV treatment ameliorated CIH-induced endothelial-dependent vasomotion and augmented nitric oxide (NO) production. As-IV administration suppressed the secretion of inflammation, oxidative stress and mitochondrial dysfunction. As-IV treatment reduced the expression of calpain-1 and restored the downregulated expression of SIRT1 and Thr¹⁷² AMPK and Ser¹¹⁷⁷ eNOS phosphorylation. The effects of calpain-1 knockout and SRT1720 were similar to the effect of As-IV on VED. These findings demonstrated that As-IV ameliorated VED induced by chronic intermittent hypoxia via the calpain-1/SIRT1/AMPK signaling pathway.