Oxidative Stress, Kinase Activity and Inflammatory Implications in Right Ventricular Hypertrophy and Heart Failure under Hypobaric Hypoxia

Escherichia coli LTB26 mutant enhances immune responses to rotavirus antigen VP8 in a mouse model

Adjuvant is a major supplementary component of vaccines to boost adaptive immune responses. To select an efficient adjuvant from the heat-labile toxin B subunit (LTB) of E. coli, four LTB mutants (numbered LTB26, LTB34, LTB57, and LTB85) were generated by multi-amino acid random replacement. Mice have been intranasally vaccinated with human rotavirus VP8 admixed. Among the four mutants, enzyme-linked immunosorbent assay (ELISA) revealed that LTB26 had enhanced mucosal immune adjuvanticity compared to LTB, showing significantly enhanced immune responses in both serum IgG and mucosal sIgA levels. The 3D modeling analysis suggested that the enhanced immune adjuvanticity of LTB26 might be due to the change of the first LTB α-helix to a β-sheet. The molecular mechanism was studied using transcriptomic and flow cytometric (FCM) analysis. The transcriptomic data demonstrated that LTB26 enhanced immune response by enhancing B cell receptor (BCR) and major histocompatibility complex (MHC) II+-related pathways. Furthermore, LTB26 promoted Th1 and Th2-type immune responses which were confirmed by detecting IFN-γ and IL-4 expression levels. Immunohistochemical analysis demonstrated that LTB26 enhanced both Th1 and Th2 type immunity. Therefore, LTB26 was a potent mucosal immune adjuvant meeting the requirement for use in human clinics in the future.

Evaluation of serum salusin-α and β levels in patients with obstructive sleep apnea

Aim: Salusin-α and salusin-β peptides are crucial in the development of cardiovascular diseases like coronary artery disease (CAD). This study compared serum levels of these peptides in patients with obstructive sleep apnea (OSA), those with both OSA and CAD. Materials & methods: Patients without OSA were included in Group 1, those with OSA alone comprised Group 2, and those with OSA and CAD were in Group 3. Results: Salusin-α level was significantly higher in controls than in Groups 2 and 3, while salusin-β levels were significantly higher in Groups 2 and 3 compared with the control group. Conclusion: Salusin-α and -β levels may be parameters that can guide the diagnosis of OSA in patients with a consistent clinical history.

Baicalin attenuates acute skin damage induced by ultraviolet B via inhibiting pyroptosis

As the outermost layer of the human body, the skin suffers from various external factors especially light damage, among which ultraviolet B (UVB) irradiation is common and possesses a relatively high biological damage capacity. Pyroptosis is a newly discovered type of programmed cell death, which can induce cell rupture and induce local inflammatory response. However, the molecular mechanisms of pyroptosis in photodamaged skin is poorly understood. Baicalin, a flavonoid extracted from the desiccated root of Scutellaria baicalensis Georgi (Huang Qin). Despite its antioxidant abilities, whether baicalin protects skin by attenuating UVB-induced pyroptosis remains unclear, which was the aim of this study. The UVB-induced acute skin damage model was established by using human immortalized keratinocytes (HaCaT cells) and Kunming (KM) strain mice. The protective dose selection for baicalin is 50 μM in vitro and 100 mg/kg in vivo. In in vitro study, UVB irradiation significantly decreased cell viability, increased cell death and oxidative stress in HaCaT cells, while pretreatment with baicalin improved these phenomena. Furthermore, the baicalin pretreatment notably suppressed nuclear factor kappa B (NF-κB) translocation, the NLRP3 inflammasome activation and gasdermin D (GSDMD) maturation, thus effectively attenuating UVB-induced pyroptosis. In in vivo study, the baicalin pretreatment mitigated epidermal hyperplasia, collagen fiber fragmentation, oxidative stress and pyroptosis in UVB-irradiated mouse skin. In a nutshell, this study suggests that baicalin could be a potential protective agent to attenuate acute skin damage induced by UVB irradiation through decreasing oxidative stress and suppressing NF-κB/NLRP3/GSDMD-involved pyroptosis.

Potential therapeutic effects of traditional Chinese medicine in acute mountain sickness: pathogenesis, mechanisms and future directions

Background and objectives

Acute mountain sickness (AMS) is a pathology with different symptoms in which the organism is not adapted to the environment that occurs under the special environment of high altitude. Its main mechanism is the organism's tissue damage caused by acute hypobaric hypoxia. Traditional Chinese medicine (TCM) theory focuses on the holistic concept. TCM has made remarkable achievements in the treatment of many mountain sicknesses. This review outlines the pathogenesis of AMS in modern and traditional medicine, the progress of animal models of AMS, and summarizes the therapeutic effects of TCM on AMS.

Methods

Using the keywords "traditional Chinese medicine," "herbal medicine," "acute mountain sickness," "high-altitude pulmonary edema," "high-altitude cerebral edema," "acute hypobaric hypoxia," and "high-altitude," all relevant TCM literature published up to November 2023 were collected from Scopus, Web of Science, PubMed, and China National Knowledge Infrastructure databases, and the key information was analyzed.

Results

We systematically summarised the effects of acute hypobaric hypoxia on the tissues of the organism, the study of the methodology for the establishment of an animal model of AMS, and retrieved 18 proprietary Chinese medicines for the clinical treatment of AMS. The therapeutic principle of medicines is mainly invigorating qi, activating blood and removing stasis. The components of botanical drugs mainly include salidroside, ginsenoside Rg1, and tetrahydrocurcumin. The mechanism of action of TCM in the treatment of AMS is mainly through the regulation of HIF-1α/NF-κB signaling pathway, inhibition of inflammatory response and oxidative stress, and enhancement of energy metabolism.

Conclusion

The main pathogenesis of AMS is unclear. Still, TCM formulas and components have been used to treat AMS through multifaceted interventions, such as compound danshen drip pills, Huangqi Baihe granules, salidroside, and ginsenoside Rg1. These components generally exert anti-AMS pharmacological effects by inhibiting the expression of VEGF, concentration of MDA and pro-inflammatory factors, down-regulating NF-κB/NLRP3 pathway, and promoting SOD and Na + -K + -ATPase activities, which attenuates acute hypobaric hypoxia-induced tissue injury. This review comprehensively analyses the application of TCM in AMS and makes suggestions for more in-depth studies in the future, aiming to provide some ideas and insights for subsequent studies.

Bawei Chenxiang Wan ameliorates right ventricular hypertrophy in rats with high altitude heart disease by SIRT3-HIF1α-PDK/PDH signaling pathway improving fatty acid and glucose metabolism

BACKGROUND

Bawei Chenxiang Wan (BCW) is among the most effective and widely used therapies for coronary heart disease and angina pectoris in Tibet. However, whether it confers protection through a right-ventricle (RV) myocardial metabolic mechanism is unknown.

METHODS

Male Sprague-Dawley rats were orally administrated with BCW, which was injected concurrently with a bolus of Sugen5416, and subjected to hypoxia exposure (SuHx; 5000 m altitude) for 4 weeks. Right ventricular hypertrophy (RVH) in high-altitude heart disease (HAHD) was assessed using Fulton's index (FI; ratio of RV to left ventricle + septum weights) and heart-weight-to-body-weight ratio (HW/BW). The effect of therapeutic administration of BCW on the RVH hemodynamics was assessed through catheterization (mean right ventricular pressure and mean pulmonary artery pressure (mRVP and mPAP, respectively)). Tissue samples were used to perform histological staining, and confirmatory analyses of mRNA and protein levels were conducted to detect alterations in the mechanisms of RVH in HAHD. The protective mechanism of BCW was further verified via cell culture.

RESULTS

BCW considerably reduced SuHx-associated RVH, as indicated by macro morphology, HW/BW ratio, FI, mPAP, mRVP, hypertrophy markers, heart function, pathological structure, and myocardial enzymes. Moreover, BCW can alleviate the disorder of glucose and fatty acid metabolism through upregulation of carnitine palmitoyltransferase1ɑ, citrate synthase, and acetyl-CoA and downregulation of glucose transport-4, phosphofructokinase, and pyruvate, which resulted in the reduced levels of free fatty acid and lactic acid and increased aerobic oxidation. This process may be mediated via the regulation of sirtuin 3 (SIRT3)-hypoxia-inducible factor 1α (HIF1α)-pyruvate dehydrogenase kinase (PDK)/pyruvate dehydrogenase (PDH) signaling pathway. Subsequently, the inhibition of SIRT3 expression by 3-TYP (a selective inhibitor of SIRT3) can reverse substantially the anti-RVH effect of BCW in HAHD, as indicated by hypertrophy marker and serum myocardial enzyme levels.

CONCLUSIONS

BCW prevented SuHx-induced RVH in HAHD via the SIRT3-HIF1ɑ-PDK/PDH signaling pathway to alleviate the disturbance in fatty acid and glucose metabolism. Therefore, BCW can be used as an alternative drug for the treatment of RVH in HAHD.

Upregulated dual oxidase 1-induced oxidative stress and caspase-1-dependent pyroptosis reflect the etiologies of heart failure

BACKGROUND

Oxidative stress is implicated in the pathogenesis of heart failure. Dual oxidase 1 (DUOX1) might be important in heart failure development through its mediating role in oxidative stress. This study was designed to evaluate the potential role of DUOX1 in heart failure.

MATERIALS AND METHODS

AC16 cells were treated with 2 µmol/L of doxorubicin (DOX) for 12, 24, and 48 h to construct a heart failure model. DUOX1 overexpression and silencing in AC16 cell were established. DUOX1 expression was detected by Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Pyroptosis and reactive oxygen species (ROS) production were measured by flow cytometry.

RESULTS

Increased DUOX1 expression levels were observed after DOX treatment for 24 h in AC16 cells. DUOX1 silencing inhibited DOX-induced pyroptosis and ROS production. The release of IL-1β, IL-18, and lactate dehydrogenase (LDH), and expression levels of pyroptosis-related proteins were also decreased. DUOX1 overexpression increased pyroptosis, ROS production, IL-1β, IL-18, and LDH release, and pyroptosis-related protein expression. N-acetyl-cysteine (NAC) significantly reversed DUOX1-induced pyroptosis, ROS, and related factors.

CONCLUSION

These results suggest that DUOX1-derived genotoxicity could promote heart failure development. In the process, oxidative stress and pyroptosis may be involved in the regulation of DUOX1 in heart failure.

The Role of Oxidative Stress and Inflammatory Parameters in Heart Failure

Heart failure (HF) remains a major medical and social problem. The NT-pro-brain natriuretic peptide (NT-proBNP) and its active form, brain-type natriuretic peptide (BNP), in a simple blood test are the gold-standard biomarkers for HF diagnosis. However, even good biomarkers such as natriuretic peptides fail to predict all the risks associated with HF due to the diversity of the mechanisms involved. The pathophysiology of HF is determined by numerous factors, including oxidative stress, inflammation, neuroendocrine activation, pathological angiogenesis, changes in apoptotic pathways, fibrosis and vascular remodeling. High readmission and mortality rates prompt a search for new markers for the diagnosis, prognosis and treatment of HF. Oxidative-stress-mediated inflammation plays a crucial role in the development of subsequent changes in the failing heart and provides a new insight into this complex mechanism. Oxidative stress and inflammatory biomarkers appear to be a promising diagnostic and prognostic tool in patients with HF. This systematic review provides an overview of the current knowledge about oxidative stress and inflammation parameters as markers of HF.

Indole-3 acetic acid induced cardiac hypertrophy in Wistar albino rats

Indole-3-acetic acid (IAA) is the most widely utilized plant growth regulator. Despite its extensive usage, IAA is often overlooked as an environmental pollutant. Due to its protein-binding nature, it also functions as a uremic toxin, contributing to its association with chronic kidney disease (CKD). While in vitro and epidemiological research have demonstrated this association, the precise impact of IAA on cardiovascular disease in animal models is unknown. The main objective of this study is to conduct a mechanistic analysis of the cardiotoxic effects caused by IAA using male Wistar albino rats as the experimental model. Three different concentrations of IAA (125, 250, 500 mg/kg) were administered for 28 days. The circulating IAA concentration mimicked previously observed levels in CKD patients. The administration of IAA led to a notable augmentation in heart size and heart-to-body weight ratio, indicating cardiac hypertrophy. Echocardiographic assessments supported these observations, revealing myocardial thickening. Biochemical and gene expression analyses further corroborated the cardiotoxic effects of IAA. Dyslipidemia, increased serum c-Troponin-I levels, decreased SOD and CAT levels, and elevated lipid peroxidation in cardiac tissue were identified. Moreover, increased expression of cardiac inflammatory biomarkers, including ANP, BNP, β-MHC, Col-III, TNF-α, and NF-κB, was also found in the IAA-treated animals. Histopathological analysis confirmed the cardiotoxic nature of IAA, providing additional evidence of its adverse effects on cardiovascular health. These results offer insights into the potential negative impact of IAA on cardiovascular function, and elucidating the underlying mechanisms of its cardiotoxicity.

SIRT1 regulates mitochondrial fission to alleviate high altitude hypoxia inducedcardiac dysfunction in rats via the PGC-1α-DRP1/FIS1/MFF pathway

High-altitude exposure has been linked to cardiac dysfunction. Silent information regulator factor 2-related enzyme 1 (sirtuin 1, SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, plays a crucial role in regulating numerous cardiovascular diseases. However, the relationship between SIRT1 and cardiac dysfunction induced by hypobaric hypoxia (HH) remains unexplored. This study aims to assess the impact of SIRT1 on HH-induced cardiac dysfunction and delve into the underlying mechanisms, both in vivo and in vitro. In this study, we have demonstrated that exposure to HH results in cardiomyocyte injury, along with the downregulation of SIRT1 and mitochondrial dysfunction. Upregulating SIRT1 significantly inhibits mitochondrial fission, improves mitochondrial function, reduces cardiomyocyte injury, and consequently enhances cardiac function in HH-exposed rats. Additionally, HH exposure triggers aberrant expression of mitochondrial fission-regulated proteins, with a decrease in PPARγ coactivator 1 alpha (PGC-1α) and mitochondrial fission factor (MFF) and an increase in mitochondrial fission 1 (FIS1) and dynamin-related protein 1 (DRP1), all of which are mitigated by SIRT1 upregulation. Furthermore, inhibiting PGC-1α diminishes the positive effects of SIRT1 regulation on the expression of DRP1, MFF, and FIS1, as well as mitochondrial fission. These findings demonstrate that SIRT1 alleviates HHinduced cardiac dysfunction by preventing mitochondrial fission through the PGC-1α-DRP1/FIS1/MFF pathway.

The impact of high-altitude and cold environment on brain and heart damage in rats with hemorrhagic shock

BACKGROUND

Hemorrhagic shock (HS) causes severe organ damage, worsened by high-altitude conditions with lower oxygen and temperatures. Existing research lacks specific insights on brain and heart damage under these conditions. This study hypothesizes that high-altitude and cold (HAC) environments exacerbate HS-induced damage in the brain and heart, aiming to improve treatment strategies.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley (SD) rats (200-250 g of weight) were randomly assigned into sham, HS + normal, HS + HAC (4,000 m), and HS + HAC (6,000 m). The HS model was established in SD rats (35% loss of total blood volume), and histopathological injuries of the brain and heart were detected using hematoxylin and eosin staining, Sirius red staining, and immunohistochemistry. Apoptosis of the brain and heart tissues was detected by terminal transferase-mediated dUTP nick end labeling (TUNEL) immunofluorescence staining. To determine the levels of tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), monocyte chemoattractant protein-1 (Mcp-1), BCL2-associated X (BAX), and myeloid cell leukemia-1 (Mcl-1) protein, western blotting assay was used.

RESULTS

The HAC environment induced pathological damage to the brain and heart and aggravated the degree of cardiac fibrosis in HS rats. However, it did not cause apoptosis of the brain and heart. In addition, it upregulated TNF-α, IFN-γ, Mcp-1, and BAX protein levels, but downregulated Mcl-1 protein levels (P < 0.05).

CONCLUSIONS

The HAC environment aggravated the degree of brain and heart damage in HS rats, which may be related to neuron nucleus pyknosis, myocardial fibrosis, and inflammatory and apoptosis activation.

Total Glucosides of Paeony Ameliorate Myocardial Injury in Chronic Heart Failure Rats by Suppressing PARP-1

Total glucosides of paeony (TGP) have a potential protective effect on chronic heart failure (CHF) rats, but the mechanism remains unclear. PARP inhibition prevents the decrease in myocardial contractility. Therefore, we aim to investigate the effects and mechanisms of TGP on CHF and the role of PARP-1 in CHF. Left anterior descending ligation rats and adriamycin-treated H9C9 cells were used as CHF models, and captopril as a positive control for in vivo experiments. We found that TGP alleviated myocardial remodeling and improved cardiac morphology and function. TGP also reduced myocardial apoptosis and autophagy, decreased inflammatory factor release, and inhibited the PARP-1 and NF-κB proteins. Through cell transfection, we found that PAPR-1 knockdown inhibited NF-κB nuclear translocation. Additionally, TGP inhibited apoptosis, autophagy, and inflammation in CHF cells, while PARP-1 overexpression partially antagonized them. In conclusion, TGP has the potential to improve CHF and PARP-1 may be a potential target.

CD73/adenosine axis exerts cardioprotection against hypobaric hypoxia-induced metabolic shift and myocarditis in a sex-dependent manner

BACKGROUND

Clinical and experimental studies have shown that the myocardial inflammatory response during pathological events varies between males and females. However, the cellular and molecular mechanisms of these sex differences remain elusive. CD73/adenosine axis has been linked to anti-inflammatory responses, but its sex-specific cardioprotective role is unclear. The present study aimed to investigate whether the CD73/adenosine axis elicits sex-dependent cardioprotection during metabolic changes and myocarditis induced by hypobaric hypoxia.

METHODS

For 7 days, male and female mice received daily injections of the CD73 inhibitor adenosine 5'- (α, β-methylene) diphosphate (APCP) 10 mg/kg/day while they were kept under normobaric normoxic and hypobaric hypoxic conditions. We evaluated the effects of hypobaric hypoxia on the CD73/adenosine axis, myocardial hypertrophy, and cardiac electrical activity and function. In addition, metabolic homeostasis and immunoregulation were investigated to clarify the sex-dependent cardioprotection of the CD73/adenosine axis.

RESULTS

Hypobaric hypoxia-induced cardiac dysfunction and adverse remodeling were more pronounced in male mice. Also, male mice had hyperactivity of the CD73/adenosine axis, which aggravated myocarditis and metabolic shift compared to female mice. In addition, CD73 inhibition triggered prostatic acid phosphatase ectonucleotidase enzymatic activity to sustain adenosine overproduction in male mice but not in female mice. Moreover, dual inhibition prostatic acid phosphatase and CD73 enzymatic activities in male mice moderated adenosine content, alleviating glycolytic shift and proinflammatory response.

CONCLUSION

The CD73/adenosine axis confers a sex-dependent cardioprotection. In addition, extracellular adenosine production in the hearts of male mice is influenced by prostatic acid phosphatase and tissue nonspecific alkaline phosphatase.

Association of altitude and frailty in Chinese older adults: using a cumulative frailty index model

Objective

The population is aging exponentially and the resulting frailty is becoming increasingly evident. We aimed to explore the association between altitude and frailty, and to identify associated factors for frailty.

Methods

This is a community-based cross-sectional survey. 1,298 participants aged ≥60 years from three different altitudes were included in the study. To quantify frailty, we constructed a frailty index (FI) and a frailty score (FS). The FI was divided into non-frailty, prefrailty, and frailty. The Odds Ratios and confidence intervals (ORs, 95%CIs) were used to evaluate the association between altitude and FI and FS in multivariate ordinal logistic regression and linear regression.

Results

There were 560 (53.1%) participants in the prefrailty and 488 (37.6%) in the frailty group. The FS increased with higher altitude (P for trend <0.001). Multivariate ordinal logistic regression analysis revealed an association between altitude and frailty, OR = 1.91 (95% CI: 1.38-2.64) in mid-high altitude and 2.49 (95% CI:1.40-4.45) in high altitude. The same trend of association was found in the univariate analysis. The FS increased by 1.69 (95% CI: 0.78-2.60) at mid-high altitude and 3.24 (95%CI:1.66-4.81) at high altitude compared to medium altitude.

Conclusion

The study indicates that high altitude exposure is an associated factor for frailty in older adults. This association become stronger with higher altitudes. As a result, it is essential to conduct early frailty screening for residents living at high altitudes.

N-Acetylcysteine Alleviates Phenylephrine-Induced Cardiomyocyte Dysfunction via Engaging PI3K/AKT Signaling Pathway

BACKGROUND

Increased reactive oxygen species (ROS) and oxidative stress response lead to cardiomyocyte hypertrophy and apoptosis, which play crucial roles in the pathogenesis of heart failure. The purpose of current research was to explore the role of antioxidant N-acetylcysteine (NAC) on cardiomyocyte dysfunction and the underlying molecular mechanisms.

METHODS AND RESULTS

Compared with control group without NAC treatment, NAC dramatically inhibited the cell size of primary cultured neonatal rat cardiomyocytes (NRCMs) tested by immunofluorescence staining and reduced the expression of representative markers associated with hypertrophic, fibrosis and apoptosis subjected to phenylephrine administration examined by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. Moreover, enhanced ROS expression was attenuated, whereas activities of makers related to oxidative stress response examined by individual assay Kits, including total antioxidation capacity (T-AOC), glutathione peroxidase (GSH-Px), and primary antioxidant enzyme Superoxide dismutase (SOD) were induced by NAC treatment in NRCMs previously treated with phenylephrine. Mechanistically, we noticed that the protein expression levels of phosphorylated phosphatidylinositol 3-kinase (PI3K) and AKT were increased by NAC stimulation. More importantly, we identified that the negative regulation of NAC in cardiomyocyte dysfunction was contributed by PI3K/AKT signaling pathway through further utilization of PI3K/AKT inhibitor (LY294002) or agonist (SC79).

CONCLUSIONS

Collected, NAC could attenuate cardiomyocyte dysfunction subjected to phenylephrine, partially by regulating the ROS-induced PI3K/AKT-dependent signaling pathway.

Identifying the Causes of Unexplained Dyspnea at High Altitude Using Normobaric Hypoxia with Echocardiography

Exposure to high altitude results in hypobaric hypoxia, leading to physiological changes in the cardiovascular system that may result in limiting symptoms, including dyspnea, fatigue, and exercise intolerance. However, it is still unclear why some patients are more susceptible to high-altitude symptoms than others. Hypoxic simulation testing (HST) simulates changes in physiology that occur at a specific altitude by asking the patients to breathe a mixture of gases with decreased oxygen content. This study aimed to determine whether the use of transthoracic echocardiography (TTE) during HST can detect the rise in right-sided pressures and the impact of hypoxia on right ventricle (RV) hemodynamics and right to left shunts, thus revealing the underlying causes of high-altitude signs and symptoms. A retrospective study was performed including consecutive patients with unexplained dyspnea at high altitude. HSTs were performed by administrating reduced FiO2 to simulate altitude levels specific to patients' history. Echocardiography images were obtained at baseline and during hypoxia. The study included 27 patients, with a mean age of 65 years, 14 patients (51.9%) were female. RV systolic pressure increased at peak hypoxia, while RV systolic function declined as shown by a significant decrease in the tricuspid annular plane systolic excursion (TAPSE), the maximum velocity achieved by the lateral tricuspid annulus during systole (S' wave), and the RV free wall longitudinal strain. Additionally, right-to-left shunt was present in 19 (70.4%) patients as identified by bubble contrast injections. Among these, the severity of the shunt increased at peak hypoxia in eight cases (42.1%), and the shunt was only evident during hypoxia in seven patients (36.8%). In conclusion, the use of TTE during HST provides valuable information by revealing the presence of symptomatic, sustained shunts and confirming the decline in RV hemodynamics, thus potentially explaining dyspnea at high altitude. Further studies are needed to establish the optimal clinical role of this physiologic method.

The Protective Effect of Chronic Intermittent Hypobaric Hypoxia on Preventing the Destruction of CD34+ Haematopoietic Stem Cells in Aplastic Anaemia by Modulating the Th1/Th2 Balance

Aplastic anaemia (AA) is a haematopoietic disorder caused by immune-mediated attack on haematopoietic stem cells (HSCs). Stem cell transplantation and immunosuppressive therapy remain the major treatment choice for AA patients but have limited benefits and undesired side effects. The aim of our study was to clarify the protective role of immunity of chronic intermittent hypobaric hypoxia (CIHH) and the underlying mechanism in AA. Our integrative analysis demonstrated that CIHH pre-treatment significantly improved haematopoiesis and survival in an AA rat model. We further confirmed that CIHH pre-treatment was closely associated with the Th1/Th2 balance and a large number of negative regulatory haematopoietic factors, such as TNF-α and IFN-γ, produced by hyperactive Th1 lymphocytes released in AA rats, which induced the death program in a large number of CD34+ HSCs by activating the Fas/FasL apoptosis pathway, while CIHH pre-treatment effectively downregulated the expression of TNF-α and IFN-γ, resulting in a reduction in Fas antigen expression in CD34+ HSCs. In summary, this study provides evidence that CIHH has good protective effect against AA by modulating immune balance in Th1/Th2 cells and may provide a new therapeutic strategy.

A newly synthesized flavone avoids COMT-catalyzed methylation and mitigates myocardial ischemia/reperfusion injury in H9C2 cells via JNK and P38 pathways

Objectives

Luteolin is a flavone that provides defense against myocardial ischemia/reperfusion (I/R) injury. However, this compound is subjected to methylation mediated by catechol-O-methyltransferase (COMT), thus influencing its pharmacological effect. To synthesize a new flavone from luteolin that avoids COMT-catalyzed methylation and find out the protective mechanism of LUA in myocardial I/R injury.

Materials and Methods

Luteolin and 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) were used to synthesize the new flavone known as LUAAPH-1 (LUA). Then, the myocardial ischemia/reperfusion injury cell model was established using H9c2 cells to detect the effect in myocardial ischemia/reperfusion regulation and to identify the underlying mechanism.

Results

Pretreatment with LUA (20 μmol/l) substantially increased cell viability while reducing cell apoptosis rate and caspase-3 expression induced by I/R, and the protective effect of LUA on cell viability was stronger than diosmetin, which is the major methylated metabolite of luteolin. In addition, intracellular reactive oxygen species (ROS) production and calcium accumulation were both inhibited by LUA. Furthermore, we identified that LUA markedly relieved the promotive effects of I/R stimulation upon JNK and p38 phosphorylation.

Conclusion

LUT pretreatment conveys significant cardioprotective effects after myocardial I/R injury, and JNK and p38 MAPK signaling pathway may be involved.

Meta-analysis reveals differential gene expression in tetralogy of Fallot versus controls

OBJECTIVES

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect in the United States. We aimed to identify genetic variations associated with TOF using meta-analysis of publicly available digital samples to spotlight targets for prevention, screening, and treatment strategies.

METHODS

We used the Search Tag Analyze Resource for Gene Expression Omnibus (STARGEO) platform to identify 39 TOF and 19 non-TOF right ventricle tissue samples from microarray data and identified upregulated and downregulated genes. Associated gene expression data were analyzed using ingenuity pathway analysis and restricted to genes with a statistically significant (p < .05) difference and an absolute experimental log ratio >0.1 between disease and control samples.

RESULTS

Our analysis identified 220 genes whose expression profiles were significantly altered in TOF vs. non-TOF samples. The most striking differences identified in gene expression included genes FBXO32, PTGES, MYL12a, and NR2F2. Some top associated canonical pathways included adrenergic signaling, estrogen receptor signaling, and the role of NFAT in cardiac hypertrophy. In general, genes involved in adaptive, defensive, and reparative cardiovascular responses showed altered expression in TOF vs. non-TOF samples.

CONCLUSIONS

We introduced the interpretation of open "big data" using the STARGEO platform to define robust genomic signatures of congenital heart disease pathology of TOF. Overall, our meta-analysis results indicated increased metabolism, inflammation, and altered gene expression in TOF patients. Estrogen receptor signaling and the role of NFAT in cardiac hypertrophy represent unique pathways upregulated in TOF patients and are potential targets for future pharmacologic treatments.

High altitude hypoxia and oxidative stress: The new hope brought by free radical scavengers

Various strategies can be employed to prevent and manage altitude illnesses, including habituation, oxygenation, nutritional support, and medication. Nevertheless, the utilization of drugs for the prevention and treatment of hypoxia is accompanied by certain adverse effects. Consequently, the quest for medications that exhibit minimal side effects while demonstrating high efficacy remains a prominent area of research. In this context, it is noteworthy that free radical scavengers exhibit remarkable anti-hypoxia activity. These scavengers effectively eliminate excessive free radicals and mitigate the production of reactive oxygen species (ROS), thereby safeguarding the body against oxidative damage induced by plateau hypoxia. In this review, we aim to elucidate the pathogenesis of plateau diseases that are triggered by hypoxia-induced oxidative stress at high altitudes. Additionally, we present a range of free radical scavengers as potential therapeutic and preventive approaches to mitigate the occurrence of common diseases associated with hypoxia at high altitudes.

The alterations of cardiac function during venovenous artificial placenta support in fetal goats

INTRODUCTION

Venovenous artificial placenta (VVAP) may mimic the intrauterine environment for maintaining fetal circulation. However, changes in ventricular function in fetal goats undergoing VVAP support remain unclear.

METHODS

Pump-assisted VVAPs were established in five fetal goats for 9 h. The myocardial performance index (Tei index), cardiac output (CO), and blood biochemical parameters were measured during VVAP support.

RESULTS

An increasing trend of the right ventricular (RV) Tei index was seen during VVAP support (p for trend < 0.01). The right ventricular cardiac output (RVCO) increased after the initiation of VVAP, while a significant trend of reduction was observed after 3 h (p for trend = 0.03). During VVAP support, we observed remarkable elevations of plasma cTnI and arterial lactic acid, which were positively correlated with the RV Tei index, but not the left ventricular (LV) Tei index, LVCO, and RVCO.

CONCLUSIONS

The RVCO increases initially while a tendency of decrease could be observed during VVAP support. Special attention should be paid to right ventricular dysfunction during VVAP support.

Diabetic Cardiomyopathy: 2023 Update by the International Multidisciplinary Board of Experts

Diabetes mellitus (DM) is considered by many the pandemic of the 21st century and is associated with multiple organ damages. Among these, cardiovascular complications are responsible for an incredible burden of mortality and morbidity in Western Countries. The study of the pathological mechanisms responsible for the cardiovascular complications in DM patients is key for the development of new therapeutic strategies. The metabolic disorders caused by hyperglycemia, insulin resistance, and dyslipidemia, results in a cascade of pathomorphological changes favoring the atherosclerotic process and leading to myocardial remodeling. Parallel to this, oxidative stress, calcium overload, mitochondrial dysfunction, activation of protein kinase C signaling pathways, myocardial lipomatosis, and low-grade inflammation of the myocardium - are the main pathways responsible for the diabetic cardiomyopathy development. This review aims to appraise and discuss the pathogenetic mechanisms behind the diabetic cardiomyopathy development.

Anaerobic threshold using sweat lactate sensor under hypoxia

We aimed to investigate the reliability and validity of sweat lactate threshold (sLT) measurement based on the real-time monitoring of the transition in sweat lactate levels (sLA) under hypoxic exercise. In this cross-sectional study, 20 healthy participants who underwent exercise tests using respiratory gas analysis under hypoxia (fraction of inspired oxygen [FiO2], 15.4 ± 0.8%) in addition to normoxia (FiO2, 20.9%) were included; we simultaneously monitored sLA transition using a wearable lactate sensor. The initial significant elevation in sLA over the baseline was defined as sLT. Under hypoxia, real-time dynamic changes in sLA were successfully visualized, including a rapid, continual rise until volitionary exhaustion and a progressive reduction in the recovery phase. High intra- and inter-evaluator reliability was demonstrated for sLT's repeat determinations (0.782 [0.607-0.898] and 0.933 [0.841-0.973]) as intraclass correlation coefficients [95% confidence interval]. sLT correlated with ventilatory threshold (VT) (r = 0.70, p < 0.01). A strong agreement was found in the Bland-Altman plot (mean difference/mean average time: - 15.5/550.8 s) under hypoxia. Our wearable device enabled continuous and real-time lactate assessment in sweat under hypoxic conditions in healthy participants with high reliability and validity, providing additional information to detect anaerobic thresholds in hypoxic conditions.

Kaempferol and ginsenoside Rg1 ameliorate acute hypobaric hypoxia induced lung injury based on network pharmacology analysis

Acute hypobaric hypoxia at high altitude can cause fatal non-cardiogenic high altitude pulmonary edema. Anti-inflammatory and anti-oxidant treatments appear to be a prospective way to alleviate acute hypoxia lung injury. Kaempferol (KA) and ginsenoside Rg1 (GRg1) can be isolated and purified from ginseng with anti-inflammatory, antioxidant, anti-carcinogenic, neuroprotective, and antiaging effects. However, their effects and pharmacological mechanisms on lung injury remains unclear. Network pharmacology analyses were used to explore potential targets of KA and GRg1 against acute hypobaric hypoxia induced lung injury. Rat lung tissues were further used for animal experiment verification. Among the putative targets of KA and GRg1 for inhibition of acute hypobaric hypoxia induced lung injury, AKT1, PIK3R1, PTK2, STAT3, HSP90AA1 and AKT2 were recognized as higher interrelated targets. And PI3K-AKT signaling pathway is considered to be the most important and relevant pathway. The rat experimental results showed that KA and GRg1 significantly improved histopathological changes and decreased pulmonary edema in rats with lung injury caused by acute hypobaric hypoxia. The concentrations of IL-6, TNF-α, MDA, SOD and CAT in rats treated with KA and GRg1 were significantly ameliorated. Protein and mRNA levels of PI3K and AKTI were significantly inhibited after KA administration. KA and GRg1 can lower lung water content, improve lung tissue damage, reduce the production of pro-inflammatory cytokines and the oxidative stress level.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Protective effects of epigallocatechin-3-gallate counteracting the chronic hypobaric hypoxia-induced myocardial injury in plain-grown rats at high altitude

Exposure to hypobaric hypoxia (HH) environment causes stress to the body, especially the oxygen-consuming organs. Chronic HH conditions have adverse effects on the myocardium. Thus, we conducted this experiment and aim to evaluate such adverse effects and explore the therapeutic role of epigallocatechin-3-gallate (EGCG) in rats' heart under chronic HH conditions. For that purpose, we transported rats from plain to a real HH environment at high altitude for establishing the HH model. At high altitude, animals were treated with EGCG while the salidroside was used as the positive control. General physiological data were collected, and routine blood test results were analyzed. Cardiac magnetic resonance (CMR) was examined to assess the structural and functional changes of the heart. Serum levels of cardiac enzymes and pro-inflammatory cytokines were examined. Oxidative markers in the left ventricle (LV) were detected. Additionally, ultrastructural and histopathological changes and apoptosis of the LV were assessed. Furthermore, the antioxidant stress-relevant proteins nuclear factor E2-related factor 2 (Nrf2) and the heme oxygenase-1 (HO-1) were detected. The experiment revealed that EGCG treatment decreased HH-induced elevation of cardiac enzymes and relieved mitochondrial damage of the LV. Notably, EGCG treatment significantly alleviated oxidative stress in the LV and inflammatory response in the blood. Western blot confirmed that EGCG significantly upregulated Nrf2 and HO-1. Therefore, EGCG may be considered a promising natural compound for treating the HH-induced myocardial injuries.

The Detrimental Effect of Pre-Treatment with Ivermectin on Myocardial Ischemia

INTRODUCTION

Ivermectin (IVM) is a broad-spectrum anti-parasitic agent with potential antibacterial, antiviral, and anti-cancer effects. There are limited studies on the effects of IVM on cardiovascular diseases, so the present study sought to determine the effects of pre-treatment with IVM on myocardial ischemia in both ex vivo and in vivo.

METHODS

In the ex vivo part, two groups of control and treated rats with IVM (0.2 mg/kg) were examined for cardiac function and arrhythmias by isolated heart perfusion. In the in vivo part, four groups, namely, control, IVM, Iso (MI), and Iso + IVM 0.2 mg/kg were used. Subcutaneous injection of isoproterenol (100 mg/kg/day) for 2 consecutive days was used for the induction of myocardial infarction (MI) in male Wistar rats. Then electrocardiogram, hemodynamic factors, cardiac hypertrophy, and malondialdehyde (MDA) levels were investigated.

RESULTS

The ex vivo results showed that administration of IVM induces cardiac arrhythmia and decreases the left ventricular maximal rate of pressure increase (contractility) and maximal rate of pressure decline (relaxation). The isoproterenol-induced MI model used as an in vivo model showed that cardiac hypertrophy were increased with no improvement in the hemodynamic and electrocardiogram pattern in the IVM-treated group in comparison to MI (Iso) group. However, the MDA level was lower in the IVM-treated group.

CONCLUSION

IVM pre-treatment demonstrates detrimental effects in cardiac ischemia through exacerbation of cardiac arrhythmia, myocardial dysfunction, and increased cardiac hypertrophy. Therefore, the use of IVM in ischemic heart patients should be done with great caution.

NLRC3 deficiency promotes hypoxia-induced pulmonary hypertension development via IKK/NF-κB p65/HIF-1α pathway

Hypoxia-induced pulmonary hypertension is a subgroup of type 3 pulmonary hypertension (PH) with the recommended treatment limited to oxygen therapy and lacks potential therapeutic targets. To investigate the role of NLRC3 in hypoxia-induced PH and its potential mechanism, we first collected lung tissues of high-altitude pulmonary hypertension (HAPH) patients. Immunohistochemistry and immunofluorescence showed that NLRC3 was downregulated and was mainly co-localized with the smooth muscle cells of the pulmonary vessels in HAPH patients. Besides, we found that NLRC3 was also expressed in endothelial cells in HAPH patients for the first time. Then, wild type (WT) and NLRC3 knockout (NLRC3-/-) mice were used to construct hypoxia models and primary pulmonary arterial smooth muscle cells (PASMCs) of rats and endothelial cells were cultured for verification. Right heart catheterization and echocardiography suggested that NLRC3 knockout promoted right ventricular systolic pressure (RVSP) up-regulation, right ventricular hypertrophy and fibrosis in hypoxia-induced mice. This study first demonstrated that NLRC3 deficiency promoted hypoxia-stimulated PASMCs proliferation, Human umbilical vein endothelial cells (HUVECs) apoptosis, migration and inflammation through IKK/NF-κB p65/HIF-1α pathway in vitro and in vivo, further promoted vascular remodeling and PH progression, which provided a new target for the treatment of hypoxia-induced PH.

The role of PI3K/AKT signaling pathway in myocardial ischemia-reperfusion injury

Myocardial ischemia has a high incidence and mortality rate, and reperfusion is currently the standard intervention. However, reperfusion may lead to further myocardial damage, known as myocardial ischemia/reperfusion injury (MIRI). There are currently no effective clinical treatments for MIRI. The PI3K/Akt signaling pathway is involved in cardiovascular health and disease and plays an important role in reducing myocardial infarct size and restoring cardiac function after MIRI. Activation of the PI3K/Akt pathway provides myocardial protection through synergistic upregulation of antioxidant, anti-inflammatory, and autophagy activities and inhibition of mitochondrial dysfunction and cardiomyocyte apoptosis. Many studies have shown that PI3K/Akt has a significant protective effect against MIRI. Here, we reviewed the molecular regulation of PI3K/Akt in MIRI and summarized the molecular mechanism by which PI3K/Akt affects MIRI, the effects of ischemic preconditioning and ischemic postconditioning, and the role of related drugs or activators targeting PI3K/Akt in MIRI, providing novel insights for the formulation of myocardial protection strategies. This review provides evidence of the role of PI3K/Akt activation in MIRI and supports its use as a therapeutic target.

Cardiovascular indicators associated with ventricular remodeling in chronic high-altitude disease: a cardiovascular MRI study

OBJECTIVE

This study aimed to assess biventricular function and mechanics in patients with the chronic high-altitude disease (CHAD) using cardiovascular MRI and explore the possible risk factors associated with ventricular remodeling.

METHODS

In this prospective study, consecutive CHAD patients and healthy controls at high-altitude (HA) and at sea level (SL) underwent cardiovascular MRI. Right ventricular (RV) and left ventricular (LV) function and global strain parameters were compared. To identify risk factors associated with ventricular remodeling, multiple linear regression analyses were used.

RESULTS

A total of 33 patients with CHAD (42.97 years ± 11.80; 23 men), 33 HA (41.18 years ± 8.58; 21 men), and 33 SL healthy controls (43.48 years ± 13.40; 21 men) were included. A Significantly decreased biventricular ejection fraction was observed in patients (all p < 0.05). Additionally, the HA group displayed lower magnitudes of biventricular longitudinal peak strain (PS) (RV,  - 13.67%  ± 4.05 vs.  - 16.22%  ± 3.03; LV,  - 14.68%  ± 2.20 vs.  - 16.19%  ± 2.51; both p < 0.05), but a higher LV circumferential PS (- 20.74%  ± 2.02 vs.  - 19.17%  ± 2.34, p < 0.05) than the SL group. Moreover, multiple linear regression analyses revealed that HGB (β = 0.548) was related to the LV remodeling index, whereas BUN (β = 0.570) was associated with the RV remodeling index.

CONCLUSIONS

With the deterioration of RV function in patients with CHAD, LV function was also impaired concomitantly. Hypoxia-induced erythrocytosis may contribute to LV impairment, while BUN was considered an independent risk factor for RV remodeling.

KEY POINTS

• A significantly lower biventricular ejection fraction was observed in patients, with a decreased magnitude of left ventricular (LV) peak systolic strain rate (radial and circumferential) and peak diastolic strain rate (all p < 0.05). • High-altitude healthy natives showed a lower biventricular longitudinal peak strain (all p < 0.05). • Hemoglobin was related to LV remodeling (β = 0.548), while BUN (β = 0.570) was independently associated with RV remodeling in CHAD patients.

MFN2 deficiency promotes cardiac response to hypobaric hypoxia by reprogramming cardiomyocyte metabolism

AIM

Under hypobaric hypoxia (HH), the heart triggers various defense mechanisms including metabolic remodeling against lack of oxygen. Mitofusin 2 (MFN2), located at the mitochondrial outer membrane, is closely involved in the regulation of mitochondrial fusion and cell metabolism. To date, however, the role of MFN2 in cardiac response to HH has not been explored.

METHODS

Loss- and gain-of-function approaches were used to investigate the role of MFN2 in cardiac response to HH. In vitro, the function of MFN2 in the contraction of primary neonatal rat cardiomyocytes under hypoxia was examined. Non-targeted metabolomics and mitochondrial respiration analyses, as well as functional experiments were performed to explore underlying molecular mechanisms.

RESULTS

Our data demonstrated that, following 4 weeks of HH, cardiac-specific MFN2 knockout (MFN2 cKO) mice exhibited significantly better cardiac function than control mice. Moreover, restoring the expression of MFN2 clearly inhibited the cardiac response to HH in MFN2 cKO mice. Importantly, MFN2 knockout significantly improved cardiac metabolic reprogramming during HH, resulting in reduced capacity for fatty acid oxidation (FAO) and oxidative phosphorylation, and increased glycolysis and ATP production. In vitro data showed that down-regulation of MFN2 promoted cardiomyocyte contractility under hypoxia. Interestingly, increased FAO through palmitate treatment decreased contractility of cardiomyocyte with MFN2 knockdown under hypoxia. Furthermore, treatment with mdivi-1, an inhibitor of mitochondrial fission, disrupted HH-induced metabolic reprogramming and subsequently promoted cardiac dysfunction in MFN2-knockout hearts.

CONCLUSION

Our findings provide the first evidence that down-regulation of MFN2 preserves cardiac function in chronic HH by promoting cardiac metabolic reprogramming.

Risk factors for mortality in patients with acute exacerbation of cor pulmonale in plateau

BACKGROUND

The risk factors for mortality might differ between patients with acute exacerbation of chronic pulmonary heart disease in plains and plateaus, while there is a lack of evidence.

METHOD

Patients diagnosed with cor pulmonale at Qinghai Provincial People's Hospital were retrospectively included between January 2012 and December 2021. The symptoms, physical and laboratory examination findings, and treatments were collected. Based on the survival within 50 days, we divided the patients into survival and death groups.

RESULTS

After 1:10 matching according to gender, age, and altitude, 673 patients were included in the study, 69 of whom died. The multivariable Cox proportional hazards analysis showed that NYHA class IV (HR = 2.03, 95%CI: 1.21-3.40, P = 0.007), type II respiratory failure (HR = 3.57, 95%CI: 1.60-7.99, P = 0.002), acid-base imbalance (HR = 1.82, 95%CI: 1.06-3.14, P = 0.031), C-reactive protein (HR = 1.04, 95%CI: 1.01-1.08, P = 0.026), and D-dimer (HR = 1.07, 95%CI: 1.01-1.13, P = 0.014) were risk factors for death in patients with cor pulmonale at high altitude. Among patients living below 2500 m, cardiac injury was a risk factor for death (HR = 2.47, 95%CI: 1.28-4.77, P = 0.007), while no significant association was observed at ≥ 2500 m (P = 0.057). On the contrary, the increase of D-dimer was only a risk factor for the death of patients living 2500 m and above (HR = 1.23, 95% CI: 1.07-1.40, P = 0.003).

CONCLUSION

NYHA class IV, type II respiratory failure, acid-base imbalance, and C- reactive protein may increase the risk of death in patients with cor pulmonale. Altitude modified the association between cardiac injury, D-dimer, and death in patients with cor pulmonale.

Eleutheroside E from pre-treatment of Acanthopanax senticosus (Rupr.etMaxim.) Harms ameliorates high-altitude-induced heart injury by regulating NLRP3 inflammasome-mediated pyroptosis via NLRP3/caspase-1 pathway

Eleutheroside E, a major natural bioactive compound in Acanthopanax senticosus (Rupr.etMaxim.) Harms, possesses anti-oxidative, anti-fatigue, anti-inflammatory, anti-bacterial and immunoregulatory effects. High-altitude hypobaric hypoxia affects blood flow and oxygen utilisation, resulting in severe heart injury that cannot be reversed, thereby eventually causing or exacerbating high-altitude heart disease and heart failure. The purpose of this study was to determine the cardioprotective effects of eleutheroside E against high-altitude-induced heart injury (HAHI), and to study the mechanisms by which this happens. A hypobaric hypoxia chamber was used in the study to simulate hypobaric hypoxia at the high altitude of 6000 m. 42 male rats were randomly assigned to 6 equal groups and pre-treated with saline, eleutheroside E 100 mg/kg, eleutheroside E 50 mg/kg, or nigericin 4 mg/kg. Eleutheroside E exhibited significant dose-dependent effects on a rat model of HAHI by suppressing inflammation and pyroptosis. Eleutheroside E downregulated the expressions of brain natriuretic peptide (BNP), creatine kinase isoenzymes (CK-MB) and lactic dehydrogenase (LDH). Moreover, The ECG also showed eleutheroside E improved the changes in QT interval, corrected QT interval, QRS interval and heart rate. Eleutheroside E remarkably suppressed the expressions of NLRP3/caspase-1-related proteins and pro-inflammatory factors in heart tissue of the model rats. Nigericin, known as an agonist of NLRP3 inflammasome-mediated pyroptosis, reversed the effects of eleutheroside E. Eleutheroside E prevented HAHI and inhibited inflammation and pyroptosis via the NLRP3/caspase-1 signalling pathway. Taken together, eleutheroside E is a prospective, effective, safe and inexpensive agent that can be used to treat HAHI.

A narrative review of the mechanisms and consequences of intermittent hypoxia and the role of advanced analytic techniques in pediatric autonomic disorders

Disorders of autonomic functions are typically characterized by disturbances in multiple organ systems. These disturbances are often comorbidities of common and rare diseases, such as epilepsy, sleep apnea, Rett syndrome, congenital heart disease or mitochondrial diseases. Characteristic of many autonomic disorders is the association with intermittent hypoxia and oxidative stress, which can cause or exaggerate a variety of other autonomic dysfunctions, making the treatment and management of these syndromes very complex. In this review we discuss the cellular mechanisms by which intermittent hypoxia can trigger a cascade of molecular, cellular and network events that result in the dysregulation of multiple organ systems. We also describe the importance of computational approaches, artificial intelligence and the analysis of big data to better characterize and recognize the interconnectedness of the various autonomic and non-autonomic symptoms. These techniques can lead to a better understanding of the progression of autonomic disorders, ultimately resulting in better care and management.

Effects of Zinc on the Right Cardiovascular Circuit in Long-Term Hypobaric Hypoxia in Wistar Rats

Hypobaric hypoxia under chromic conditions triggers hypoxic pulmonary vasoconstriction (HPV) and right ventricular hypertrophy (RVH). The role of zinc (Zn) under hypoxia is controversial and remains unclear. We evaluated the effect of Zn supplementation in prolonged hypobaric hypoxia on HIF2α/MTF-1/MT/ZIP12/PKCε pathway in the lung and RVH. Wistar rats were exposed to hypobaric hypoxia for 30 days and randomly allocated into three groups: chronic hypoxia (CH); intermittent hypoxia (2 days hypoxia/2 days normoxia; CIH); and normoxia (sea level control; NX). Each group was subdivided (n = 8) to receive either 1% Zn sulfate solution (z) or saline (s) intraperitoneally. Body weight, hemoglobin, and RVH were measured. Zn levels were evaluated in plasma and lung tissue. Additionally, the lipid peroxidation levels, HIF2α/MTF-1/MT/ZIP12/PKCε protein expression and pulmonary artery remodeling were measured in the lung. The CIH and CH groups showed decreased plasma Zn and body weight and increased hemoglobin, RVH, and vascular remodeling; the CH group also showed increased lipid peroxidation. Zn administration under hypobaric hypoxia upregulated the HIF2α/MTF-1/MT/ZIP12/PKCε pathway and increased RVH in the intermittent zinc group. Under intermittent hypobaric hypoxia, Zn dysregulation could participate in RVH development through alterations in the pulmonary HIF2α/MTF1/MT/ZIP12/PKCε pathway.

Chronic intermittent hypobaric hypoxia induces cardiovascular dysfunction in a high-altitude working shift model

AIMS

Chronic intermittent hypobaric hypoxia (CIHH) exposure due to shift work occurs mainly in 4 × 4 or 7 × 7 days shifts in mining, astronomy, and customs activities, among other institutions. However, the long-lasting effects of CIHH on cardiovascular structure and function are not well characterized. We aimed to investigate the effects of CIHH on the cardiac and vascular response of adult rats simulating high-altitude (4600 m) x low-altitude (760 m) working shifts.

MAIN METHODS

We analyzed in vivo cardiac function through echocardiography, ex vivo vascular reactivity by wire myography, and in vitro cardiac morphology by histology and protein expression and immunolocalization by molecular biology and immunohistochemistry techniques in 12 rats, 6 exposed to CIHH in the hypoxic chamber, and respective normobaric normoxic controls (n = 6).

KEY FINDINGS

CIHH induced cardiac dysfunction with left and right ventricle remodeling, associated with an increased collagen content in the right ventricle. In addition, CIHH increased HIF-1α levels in both ventricles. These changes are associated with decreased antioxidant capacity in cardiac tissue. Conversely, CIHH decreased contractile capacity with a marked decreased in nitric oxide-dependent vasodilation in both, carotid and femoral arteries.

SIGNIFICANCE

These data suggest that CIHH induces cardiac and vascular dysfunction by ventricular remodeling and impaired vascular vasodilator function. Our findings highlight the impact of CIHH in cardiovascular function and the importance of a periodic cardiovascular evaluation in high-altitude workers.

Bioinformatics exploration of potential common therapeutic targets for systemic and pulmonary arterial hypertension-induced myocardial hypertrophy

Systemic and pulmonary arterial hypertension (PAH) can induce left and right ventricular hypertrophy, respectively, but common therapeutic targets for both left and right hypertrophy are limited. In this study, we attempt to explore potential common therapeutic targets and screen out potential target drugs for further study. Cardiac mRNA expression profiles in mice with transverse aortic constriction (TAC) and pulmonary arterial constriction (PAC) are obtained from online databases. After bioinformatics analyses, we generate TAC and PAC mouse models to validate the phenotypes of cardiac remodelling as well as the identified hub genes. Bioinformatics analyses show that there are 214 independent differentially expressed genes (DEGs) in GSE136308 (TAC related) and 2607 independent DEGs in GSE30922 (PAC related), while 547 shared DEGs are associated with the function of the extracellular matrix (ECM) or involved in the PI3K-Akt signaling pathway, cytokine-cytokine receptor interactions, and ECM-receptor interactions. We identifyd Fn1, Il6, Col1a1, Igf1, Col1a2, Timp1, Col3a1, Cd44, Ctgf and Postn as hub genes of the shared DEGs, and most of them are associated with myocardial fibrosis. Those hub genes and phenotypes of cardiac remodelling are validated in our TAC and PAC mouse models. Furthermore, we identify dehydroisoandrosterone (DHEA), iloprost and 4,5-dianilinophthalimide (DAPH) as potential therapeutic drugs targeting both left and right ventricular hypertrophy and validate the effect of DHEA. These findings suggest that DHEA could be an effective drug for pressure overload-induced left or right ventricular hypertrophy by regulating the shared hub differentially expressed genes associated with fibrosis.

Protective effects of the Terminalia bellirica tannin-induced Nrf2/HO-1 signaling pathway in rats with high-altitude pulmonary hypertension

BACKGROUND

Oxidative stress and endothelial cell dysfunction induced by high-altitude hypoxia have important roles in the pathological process of high-altitude pulmonary hypertension (HAPH). Tannins present in Terminalia bellirica (Gaertn.) Roxb. (TTR) have pharmacological activities that produce oxidation resistance and exert anti-inflammatory effects. Whether TTR exerts a protective effect on HAPH remains unknown.

METHODS

A rat model of HAPH was established. The mean pulmonary arterial pressure (mPAP) of the animals was measured, the serum levels of SOD, MDA, and GSH-Px were measured using ELISA, and the expression of Bax, Bcl-2, Nrf2, and HO-1 proteins in the lung tissue of each group of rats was measured using Western blotting. Pathological changes in the lung tissue were also observed. A model of damage to H₂O₂-induced pulmonary artery endothelial cells (PAECs) was generated, and cell proliferation was measured using CCK-8 assays. Flow cytometry was used to measure ROS levels in PAECs. Western blotting was used to detect the expression of Bax, Bcl-2, Nrf2, and HO-1 proteins in PAECs.

RESULTS

The hemodynamic and pathologic findings showed that the mPAP of HAPH rats increased markedly, and the vascular wall thickness increased (P < 0.05). TTR reduced mPAP, alleviated or slowed pulmonary arterial remodeling, increased GSH-Px and SOD activity, lowered the level of MDA (P < 0.05), and downregulated the expression of Bax in the lung tissues of HAPH rats, while the expression of Bcl-2, Nrf2, and HO-1 was upregulated (P < 0.05). The results of the cell experiments showed that TTR inhibited H₂O₂-induced PAEC apoptosis and ROS production (P < 0.05), downregulated the expression of Bax in PAECs, and upregulated the expression of Bcl-2, Nrf2, and HO-1 (P < 0.05).

CONCLUSION

The results suggest that TTR reduces pulmonary arterial pressure, decreases oxidative stress during HAPH, and exerts protective effects in rats with HAPH and that its mechanism of action is related to regulation of the Nrf2/HO-1 signaling pathway.

Jiedu Quyu Decoction mitigates monocrotaline-induced right-sided heart failure associated with pulmonary artery hypertension by inhibiting NLRP3 inflammasome in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Right-side heart failure could accelerate mortality in patients of pulmonary hypertension, Jiedu Quyu Decoction (JDQYF) was used to manage pulmonary hypertension, but its right-sided heart protective effect associated with pulmonary artery hypertension is still unclear.

AIM OF THE STUDY

Here, we evaluated the therapeutic effect of JDQYF on monocrotaline-induced right-sided heart failure associated with pulmonary arterial hypertension in Sprague-Dawley (SD) rats and investigated the potential mechanism of action.

MATERIALS AND METHODS

The main chemical components of JDQYF were detected and analyzed using ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry. The effects of JDQYF were investigated using a rat model of monocrotaline-induced right-sided heart failure associated with pulmonary arterial hypertension. We assessed the morphology of cardiac tissue using histopathology and the structure and function of the right heart using echocardiography. The biomarkers of heart failure, atrial natriuretic peptide and B-type natriuretic peptide, as well as serum pro-inflammatory markers, interleukin (IL)-1β, and IL-18, were measured by enzyme-linked immunosorbent assay (ELISA). Furthermore, the mRNA and protein expression levels of NLRP3 (NOD-, LRR-, and pyrin domain-containing 3), capase-1, IL-1β, and IL-18 in the right heart tissue were examined by real-time quantitative reverse transcription PCR and western blotting.

RESULTS

JDQYF improved ventricular function, alleviated pathological lesions in the right cardiac tissue, reduced the expression levels of biomarkers of heart failure and serum pro-inflammatory factors (IL-1β and IL-18), and downregulated the mRNA and protein expression levels of NLRP3, caspase-1, IL-1β, and IL-18 in the right cardiac tissue.

CONCLUSIONS

JDQYF possesses cardioprotective effect against right heart failure induced by pulmonary arterial hypertension, possibly owing to reduction of cardiac inflammation through the inhibition of NLRP3 inflammasome activation.

Clinical characteristics and predictors of pulmonary hypertension in chronic obstructive pulmonary disease at different altitudes

BACKGROUND

Pulmonary hypertension (PH) is a common complication in patients with chronic obstructive pulmonary disease (COPD) and is closely associated with poor prognosis. However, studies on the predictors of PH in COPD patients are limited, especially in populations living at high altitude (HA).

OBJECTIVES

To investigate the differences in the clinical characteristics and predictors of patients with COPD/COPD and PH (COPD-PH) from low altitude (LA, 600 m) and HA (2200 m).

METHODS

We performed a cross-sectional survey of 228 COPD patients of Han nationality admitted to the respiratory department of Qinghai People's Hospital (N = 113) and West China Hospital of Sichuan University (N = 115) between March 2019 and June 2021. PH was defined as a pulmonary arterial systolic pressure (PASP) > 36 mmHg measured using transthoracic echocardiography (TTE).

RESULTS

The proportion of PH in COPD patients living at HA was higher than that in patients living at LA (60.2% vs. 31.3%). COPD-PH patients from HA showed significantly different in baseline characteristics, laboratory tests and pulmonary function test. Multivariate logistic regression analysis indicated that the predictors of PH in COPD patients were different between the HA and LA groups.

CONCLUSIONS

The COPD patients living at HA had a higher proportion of PH than those living at LA. At LA, increased B-type natriuretic peptide (BNP) and direct bilirubin (DB) were predictors for PH in COPD patients. However, at HA, increased DB was a predictor of PH in COPD patients.

The involvement of hypoxia inducible factor-1α on the proportion of three types of haemocytes in Chinese mitten crab under hypoxia stress

Hypoxia triggers diverse cell physiological processes, and the hypoxia inducible factors (HIFs) are a family of heterodimeric transcription factors that function as master regulators to respond to hypoxia in different cells. However, the knowledge about the hypoxic responses especially cell alteration mediated by HIFs under hypoxia stress is still limited in crustaceans. In the present study, a hypoxia-inducible factor-1α (HIF-1α) gene was identified (designed as EsHIF-1α). The relative mRNA expression level of EsHIF-1α was highest in hyalinocytes and lowest in granulocytes among three types of haemocytes in crabs. Hypoxia could significantly increase the EsHIF-1α protein expression level in haemocytes. Meanwhile, the proportion of hyalinocytes began to increase from 3 h post hypoxia treatment, and reached the highest level at 24 h. However, the opposite variation in proportion of granulocytes was observed under hypoxia stress. Further investigation showed that the inhibition of EsHIF-1α induced by KC7F2 (HIF-1α inhibitor) could lead to the significant decrease in the proportion of hyalinocytes under hypoxia stress, and also resulted in an increase of granulocytes proportion. While, after EsHIF-1α was activated by IOX4 (HIF-1α activator), the proportion of hyalinocytes was significantly up-regulated and the proportion of granulocytes was significantly down-regulated under post hypoxia treatment. These results collectively suggested that EsHIF-1α was involved in the regulation of proportion of three types of haemocytes induced by hypoxia stress, which provided vital insight into the understanding of the crosstalk between hypoxia and cell development in invertebrates.

FIMICS: A panel of long noncoding RNAs for cardiovascular conditions

Cardiovascular disorders such as heart failure are leading causes of mortality. Patient stratification via identification of novel biomarkers could improve management of cardiovascular diseases of complex etiologies. Long-noncoding RNAs (lncRNAs) are highly tissue-specific in nature and have emerged as important biomarkers in human diseases. In this study, we aimed to identify cardiac-enriched lncRNAs as potential biomarkers for cardiovascular conditions. Deep RNA sequencing and quantitative PCR identified differentially expressed lncRNAs between failing and non-failing hearts. An independent dataset was used to evaluate the enrichment of lncRNAs in normal hearts. We identified a panel of 2906 lncRNAs, named FIMICS, that were either cardiac-enriched or differentially expressed between failing and non-failing hearts. Expression of lncRNAs in blood samples differentiated patients with myocarditis and acute myocardial infarction. We hereby present the FIMICS panel, a readily available tool to provide insights into cardiovascular pathologies and which could be helpful for diagnosis, monitoring and prognosis purposes.

Occlusion preconditioned mice are resilient to hypobaric hypoxia-induced myocarditis and arrhythmias due to enhanced immunomodulation, metabolic homeostasis, and antioxidants defense

Background

Sea-level residents experience altitude sickness when they hike or visit altitudes above ~2,500 m due to the hypobaric hypoxia (HH) conditions at such places. HH has been shown to drive cardiac inflammation in both ventricles by inducing maladaptive metabolic reprogramming of macrophages, which evokes aggravated proinflammatory responses, promoting myocarditis, fibrotic remodeling, arrhythmias, heart failure, and sudden deaths. The use of salidroside or altitude preconditioning (AP) before visiting high altitudes has been extensively shown to exert cardioprotective effects. Even so, both therapeutic interventions have geographical limitations and/or are inaccessible/unavailable to the majority of the population as drawbacks. Meanwhile, occlusion preconditioning (OP) has been extensively demonstrated to prevent hypoxia-induced cardiomyocyte damage by triggering endogenous cardioprotective cascades to mitigate myocardial damage. Herein, with the notion that OP can be conveniently applied anywhere, we sought to explore it as an alternative therapeutic intervention for preventing HH-induced myocarditis, remodeling, and arrhythmias.

Methods

OP intervention (6 cycles of 5 min occlusion with 200 mmHg for 5 min and 5 min reperfusion at 0 mmHg - applying to alternate hindlimb daily for 7 consecutive days) was performed, and its impact on cardiac electric activity, immunoregulation, myocardial remodeling, metabolic homeostasis, oxidative stress responses, and behavioral outcomes were assessed before and after exposure to HH in mice. In humans, before and after the application of OP intervention (6 cycles of 5 min occlusion with 130% of systolic pressure and 5 min reperfusion at 0 mmHg - applying to alternate upper limb daily for 6 consecutive days), all subjects were assessed by cardiopulmonary exercise testing (CPET).

Results

Comparing the outcomes of OP to AP intervention, we observed that similar to the latter, OP preserved cardiac electric activity, mitigated maladaptive myocardial remodeling, induced adaptive immunomodulation and metabolic homeostasis in the heart, enhanced antioxidant defenses, and conferred resistance against HH-induce anxiety-related behavior. Additionally, OP enhanced respiratory and oxygen-carrying capacity, metabolic homeostasis, and endurance in humans.

Conclusions

Overall, these findings demonstrate that OP is a potent alternative therapeutic intervention for preventing hypoxia-induced myocarditis, cardiac remodeling, arrhythmias, and cardiometabolic disorders and could potentially ameliorate the progression of other inflammatory, metabolic, and oxidative stress-related diseases.

Acute hypoxia induced dysregulation of clock-controlled ovary functions

High altitudes or exposure to hypoxia leads to female reproductive disorders. Circadian clocks are intrinsic time-tracking systems that enable organisms to adapt to the Earth's 24-h light/dark cycle, which can be entrained by other environmental stimuli to regulate physiological and pathological responses. In this study, we focused on whether ovarian circadian clock proteins were involved in regulating female reproductive dysfunction under hypoxic conditions. Hypobaric hypoxia was found to induce a significantly prolonged estrous cycle in female mice, accompanied by follicular atresia, pituitary/ovarian hormone synthesis disorder, and decreased LHCGR expression in the ovaries. Under the same conditions, the levels of the ovarian circadian clock proteins, CLOCK and BMAL1, were suppressed, whereas E4BP4 levels were upregulated. Results from granulosa cells (GCs) further demonstrated that CLOCK: BMAL1 and E4BP4 function as transcriptional activators and repressors of LHCGR in ovarian GCs, respectively, whose responses were mediated by HIF1ɑ-dependent (E4BP4 upregulation) and ɑ-independent (CLOCK and BMAL1 downregulation) manners. The LHCGR agonist was shown to efficiently recover the impairment of ovulation-related gene (EREG and PGR) expression in GCs induced by hypoxia. We conclude that hypoxia exposure causes dysregulation of ovarian circadian clock protein (CLOCK, BMAL1, and E4BP4) expression, which mediates female reproductive dysfunction by impairing LHCGR-dependent signaling events. Adjusting the timing system or recovering the LHCGR level in the ovaries may be helpful in overcoming female reproductive disorders occurring in the highlands.

Xinyang Tablet attenuates chronic hypoxia-induced right ventricular remodeling via inhibiting cardiomyocytes apoptosis

BACKGROUND

Hypoxia-induced pulmonary hypertension (HPH) is one of the fatal pathologies developed under hypobaric hypoxia and eventually leads to right ventricular (RV) remodeling and RV failure. Clinically, the mortality rate of RV failure caused by HPH is high and lacks effective drugs. Xinyang Tablet (XYT), a traditional Chinese medicine exhibits significant efficacy in the treatment of congestive heart failure and cardiac dysfunction. However, the effects of XYT on chronic hypoxia-induced RV failure are not clear.

METHODS

The content of XYT was analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Sprague-Dawley (SD) rats were housed in a hypobaric chamber (equal to the parameter in altitude 5500 m) for 21 days to obtain the RV remodeling model. Electrocardiogram (ECG) and hemodynamic parameters were measured by iWorx Acquisition & Analysis System. Pathological morphological changes in the RV and pulmonary vessels were observed by H&E staining and Masson's trichrome staining. Myocardial apoptosis was tested by TUNEL assay. Protein expression levels of TNF-α, IL-6, Bax, Bcl-2, and caspase-3 in the RV and H9c2 cells were detected by western blot. Meanwhile, H9c2 cells were induced by CoCl₂ to establish a hypoxia injury model to verify the protective effect and mechanisms of XYT. A CCK-8 assay was performed to determine the viability of H9c2 cells. CoCl₂-induced apoptosis was detected by Annexin-FITC/PI flow cytometry and Hoechst 33,258 staining.

RESULTS

XYT remarkably improved RV hemodynamic disorder and ECG parameters. XYT attenuated hypoxia-induced pathological injury in RV and pulmonary vessels. We also observed that XYT treatment decreased the expression levels of TNF-α, IL-6, Bax/Bcl-2 ratio, and the numbers of myocardial apoptosis in RV. In H9c2 myocardial hypoxia model, XYT protected H9c2 cells against Cobalt chloride (CoCl₂)-induced apoptosis. We also found that XYT could antagonize CoCl₂-induced apoptosis through upregulating Bcl-2, inhibiting Bax and caspase-3 expression.

CONCLUSIONS

We concluded that XYT improved hypoxia-induced RV remodeling and protected against cardiac injury by inhibiting apoptosis pathway in vivo and vitro models, which may be a promising therapeutic strategy for clinical management of hypoxia-induced cardiac injury.

Inflammation in Pulmonary Hypertension and Edema Induced by Hypobaric Hypoxia Exposure

Exposure to high altitudes generates a decrease in the partial pressure of oxygen, triggering a hypobaric hypoxic condition. This condition produces pathophysiologic alterations in an organism. In the lung, one of the principal responses to hypoxia is the development of hypoxic pulmonary vasoconstriction (HPV), which improves gas exchange. However, when HPV is exacerbated, it induces high-altitude pulmonary hypertension (HAPH). Another important illness in hypobaric hypoxia is high-altitude pulmonary edema (HAPE), which occurs under acute exposure. Several studies have shown that inflammatory processes are activated in high-altitude illnesses, highlighting the importance of the crosstalk between hypoxia and inflammation. The aim of this review is to determine the inflammatory pathways involved in hypobaric hypoxia, to investigate the key role of inflammation in lung pathologies, such as HAPH and HAPE, and to summarize different anti-inflammatory treatment approaches for these high-altitude illnesses. In conclusion, both HAPE and HAPH show an increase in inflammatory cell infiltration (macrophages and neutrophils), cytokine levels (IL-6, TNF-α and IL-1β), chemokine levels (MCP-1), and cell adhesion molecule levels (ICAM-1 and VCAM-1), and anti-inflammatory treatments (decreasing all inflammatory components mentioned above) seem to be promising mitigation strategies for treating lung pathologies associated with high-altitude exposure.

Identifying the Effect of Nuanxin Capsules on Myocardial Injury Induced by Chronic Hypoxia via Network Pharmacology Analysis and Experimental Validation

Nuanxin capsule (NX), an in-hospital preparation of Guangdong Provincial Hospital of Chinese Medicine, has been used in heart failure (HF) treatment for 15 years, but its mechanism and protective effect have not been investigated. This study was aimed at exploring the mechanism and protective effect of NX on HF treatment via network pharmacology analysis and experimental validation. Network pharmacology analysis predicted that NX was involved in the regulation of response to apoptotic process and hypoxia via protecting cellular damage and mitochondrial dysfunction against chronic hypoxia. Its mechanism may be involved in the regulation of the PI3K-Akt signaling pathway, HIF-1 signaling pathway, AMPK signaling pathway, and MAPK signaling pathway. Experimental validation indicated that NX was capable of improving cellular viability, restoring cellular morphology, and suppressing cellular apoptosis cellular. NX also exerted cardioprotection by inhibiting mitochondrial membrane potential injury and protecting mitochondrial respiratory and energy metabolism in a chronic hypoxia cellular model, which was consistent with the results of network pharmacology prediction. In addition, the screened active compounds of NX did have a good binding with their key targets, indicating NX may exert protective effect through multicompounds and multitargets. In conclusion, NX had a protective effect on HF through cellular and mitochondrial protection against chronic hypoxia via multicompounds, multitargets, and multipathways, and its mechanism may be involved in modulating the PI3K-Akt signaling pathway, HIF-1 signaling pathway, AMPK signaling pathway, and MAPK signaling pathway.

Alterations in gut microbiota and metabolites associated with altitude-induced cardiac hypertrophy in rats during hypobaric hypoxia challenge

The gut microbiota is involved in host responses to high altitude. However, the dynamics of intestinal microecology and their association with altitude-related illness are poorly understood. Here, we used a rat model of hypobaric hypoxia challenge to mimic plateau exposure and monitored the gut microbiome, short-chain fatty acids (SCFAs), and bile acids (BAs) over 28 d. We identified weight loss, polycythemia, and pathological cardiac hypertrophy in hypoxic rats, accompanied by a large compositional shift in the gut microbiota, which is mainly driven by the bacterial families of Prevotellaceae, Porphyromonadaceae, and Streptococcaceae. The aberrant gut microbiota was characterized by increased abundance of the Parabacteroides, Alistipes, and Lactococcus genera and a larger Bacteroides to Prevotella ratio. Trans-omics analyses showed that the gut microbiome was significantly correlated with the metabolic abnormalities of SCFAs and BAs in feces, suggesting an interaction network remodeling of the microbiome-metabolome after the hypobaric hypoxia challenge. Interestingly, the transplantation of fecal microbiota significantly increased the diversity of the gut microbiota, partially inhibited the increased abundance of the Bacteroides and Alistipes genera, restored the decrease of plasma propionate, and moderately ameliorated cardiac hypertrophy in hypoxic rats. Our results provide an insight into the longitudinal changes in intestinal microecology during the hypobaric hypoxia challenge. Abnormalities in the gut microbiota and microbial metabolites contribute to the development of high-altitude heart disease in rats.

Mining Potential Drug Targets and Constructing Diagnostic Models for Heart Failure Based on miRNA-mRNA Networks

Heart failure (HF) is a globally prevalent cardiovascular disease, but effective drug targets and diagnostic models are still lacking. This study was designed to investigate effective drug targets and diagnostic models for HF in terms of miRNA targets, hoping to contribute to the understanding and treatment of HF. Using HF miRNA and gene expression profile data from the GEO database, we analyzed differentially expressed miRNAs/gene identification in HF using Limma and predicted miRNA targets by the online TargetScan database. Subsequently, gene set enrichment analysis and annotation were performed using WebGestaltR package. Protein-protein interactions were identified using the STRING database. The proximity of drugs to treat HF was also calculated and predicted for potential target therapeutic drug. In addition, further drug identification was performed by molecular docking. Finally, diagnostic models were constructed based on differential miRNAs. The GEO dataset was used to screen 66 differentially expressed miRNAs, incorporating 56 downregulated miRNAs and 10 upregulated miRNAs. The JAK-STAT signaling pathway, MAPK signaling pathway, p53 signaling pathway, Prolactin signaling pathway, and TGF-beta signaling pathway were enriched, as shown by KEGG enrichment analysis on the target genes. In addition, we found that 83 genes were upregulated and 92 genes were downregulated in HF patients vs. healthy individuals. Based on the inflammation-related score, hypoxia-related score, and energy metabolism-related score, we identified key miRNA-mRNA pairs and constructed an interaction network. Following that, TAP1, which had the highest expression and network connectivity in acute HF with crystal and molecular docking studies, was selected as a key candidate gene in the network. And the compound DB04847 was selected to produce a large number of favorable interactions with TAP1 protein. Finally, we constructed two diagnostic models based on the differential miRNAs hsa-miR-6785-5p and hsa-miR-4443. In conclusion, we identified TAP1, a key candidate gene in the diagnosis and treatment of HF, and determined that compound DB04847 is highly likely to be a potential inhibitor of TAP1. The TAP1 gene was also found to be regulated by hsa-miR-6785-5p and hsa-miR-4443, and a diagnostic model was constructed. This provides a new promising direction to improve the diagnosis, prognosis, and treatment outcome and guide more effective immunotherapy strategies of HF.

Rhodiola crenulate alleviates hypobaric hypoxia-induced brain injury via adjusting NF-κB/NLRP3-mediated inflammation

BACKGROUND

Rhodiola crenulate (R. crenulate), a famous Tibetan medicine, has been demonstrated to possess superiorly protective effects in high-altitude hypoxic brain injury (HHBI). However, its mechanisms on HHBI are still largely unknown.

METHODS

Herein, the protective effects and underlying mechanisms of R. crenulate on HHBI of BABL/c mice were explored through in vivo experiments. The mice model of HHBI was established using an animal hypobaric and hypoxic chamber. R. crenulate extract (RCE) (0.5, 1.0 and 2.0 g/kg) was given by gavage for 7 days. Pathological changes and neuronal viability of mice hippocampus and cortex were evaluated using H&E and Nissl staining, respectively. The brain water content (BWC) in mice was determined by calculating the ratio of dry to wet weight of brain tissue. And serum of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH-Px) and lactate dehydrogenase (LDH) were detected via commercial biochemical kits. Synchronously, the contents of total antioxidant capacity (T-AOC), lactic acid (LA), adenosine triphosphate (ATP), succinate dehydrogenase (SDH), pyruvate kinase (PK), Ca²⁺-Mg²⁺-ATPcase, Na⁺-K⁺-ATPcase, TNF-α, IL-1β and IL-6 in brain tissue were quantitative analysis by corresponding ELISA assay. Subsequently, NLRP3, ZO-1, claudin-5, occluding, p-p65, p65, ASC, cleaved-caspase-1, caspase-1 and IL-18 were determined by immunofluorescent and western blot analyses.

RESULTS

The results demonstrated that RCE remarkably alleviated pathological damage, BWC, as well enhanced neuronal viability. Furthermore, the oxidative stress injuries were reversely abrogated after RCE treatment, evidenced by the increases of SOD, GSH-Px and T-AOC, while the decreases of MDA and LDH contents. Marvelously, the administration of RCE rectified and balanced the abnormal energy metabolism via elevating the levels of ATP, SDH, PK, Ca²⁺-Mg²⁺-ATPcase and Na⁺-K⁺-ATPcase, and lowering LA. Simultaneously, the expression of tight junction proteins (ZO-1, claudin-5 and occludin) was enhanced, illustrating RCE treatment might maintain the integrity of blood-brain barrier (BBB). Additionally, RCE treatment confined the contents of IL-6, IL-1β and TNF-α, and attenuated fluorescent signal of NLRP3 protein. Concurrently, the results of western blot indicated that RCE treatment dramatically restrained p-p65/p65, ASC, NLRP3, cleaved-caspase-1/caspase-1 and IL-18 protein expressions in brain tissues of mice.

CONCLUSION

RCE may afford a protectively intervention in HHBI of mice through suppressing the oxidative stress, improving energy metabolism and the integrity of BBB, and subsiding inflammatory responses via the NF-κB/NLRP3 signaling pathway. As a promising agent for the treatment of mice HHBI, the deep-crossing molecular mechanisms of R. crenulate still needs to be further elucidated to identify novel core hub targets.