Novel insights into plasma biomarker candidates in patients with chronic mountain sickness based on proteomics

Brassica rapa L. polysaccharide mitigates hypobaric hypoxia-induced oxidation and intestinal damage via microbiome modulation

The high-altitude, low-pressure, and hypoxia environment poses a significant threat to human health, particularly causing intestinal damage and disrupting gut microbiota. This study investigates the protective effects of Brassica rapa L. crude polysaccharides (BRP) on intestinal damage in mice exposed to hypobaric hypoxic conditions. Results showed that oxidative stress and inflammation levels were elevated in the hypoxia group, while BRP intervention significantly increased antioxidant enzyme activities (SOD, GSH-Px, T-AOC) and reduced inflammatory markers (IL-6, IL-1β, TNF-α). BRP also restored intestinal barrier function by enhancing claudin-1, occludin, and ZO-1 expression. Notably Chromatographic and metagenomic analyses revealed that BRP enriched butyrate levels, promoted beneficial bacteria like Akkermansia muciniphila and Leuconostoc lactis, and upregulated L-arginine biosynthesis II and L-methionine biosynthesis III pathways to enhance antioxidant activity. Fecal microbiota transfer experiments confirmed the role of gut microbiota in mediating BRP's protective effects, providing valuable insights into prebiotic-based therapeutic strategies for hypobaric hypoxia-induced intestinal damage.

Serum proteome profiling of plateau acclimatization in men using Olink proteomics approach

Plateau acclimatization involves adaptive changes in the body's neurohumoral regulation and metabolic processes due to hypoxic conditions at high altitudes. This study utilizes Olink targeted proteomics to analyze serum protein expression differences in Han Chinese individuals acclimatized for 6 months-1 year at 4500 and 5300 m altitudes, compared to those residing at sea level. The objective is to elucidate the proteins' roles in tissue and cellular adaptation to hypoxia. We identified 54 metabolism-related differentially expressed proteins (DEPs) in the serum of the high-altitude group versus the sea-level group, comprising 20 significantly upregulated and 34 downregulated proteins. Notably, 2 proteins were upregulated and 11 downregulated at both 4500 and 5300 m altitudes. The top three protein correlations among DEPs included CRKL with CA13, RNASE3 with NADK, and NADK with APEX1, alongside APLP1 with CTSH, CTSH with SOST, and CTSH with NT-proBNP in inverse correlations. KEGG enrichment analysis indicated significant DEP involvement in various metabolic pathways, particularly those associated with hypoxic cellular metabolism like glycolysis/gluconeogenesis and the HIF-1 signaling pathway. Correlation with clinical phenotypes showed positive associations of SOST, RNASE3, CA13, NADK, and CRKL with SaO2 and negative correlations with Hemoglobin and Hematocrit; ALDH1A1 positively correlated with Triglyceride; and SDC4 inversely correlated with Uric acid levels. This study provides insights into specific DEPs linked to metabolic adaptations in high-altitude acclimatized individuals, offering a foundation for understanding acclimatization mechanisms and potential therapeutic targets.

[Progress in multiomics research on high altitude polycythemia]

Chronic mountain sickness (CMS) or Monge syndrome is a disease that is prevalent at altitude above 2 500 meters. High altitude polycythemia (HAPC) is one subtype of CMS. EPAS1 and EGNL1 are the most critical high-altitude adaptation genes in the genome of the Tibetan population. The HIF-PHD-VHL system plays an important role in the pathogenesis of HAPC. The protease encoded by the SENP1 gene regulates hypoxia related transcription factors such as HIF and GATA to affect the expression of EPO or EPOR involved in red blood cell generation. With the development of genetic testing and omics technology, new progress in the fields of metabolomics, proteomics and metabolomics has been made in the pathogenesis of HAPC. The above new research results provide a preliminary basis for bone marrow hematoecology and hematopoietic regulation of HAPC. The diagnostic criteria for CMS have certain limitations, especially in patients with excessive erythrocytosis who should undergo genetic testing recommended for congenital and polycythemia vera. This article provides a review of the latest research on HAPC in various omics techniques, hematopoietic regulation and diagnostic processes which is more conducive to understand the pathogenesis. The clinical diagnosis of excessive erythrocytosis emphasizes the importance of genetic testing.

Urinary proteomics for noninvasive monitoring of biomarkers of chronic mountain sickness in a young adult population using data-independent acquisition (DIA)-based mass spectrometry

Different populations exhibit varying pathophysiological responses to plateau environments. Therefore, it is crucial to identify molecular markers in body fluids with high specificity and sensitivity to aid in determination. Proteomics offers a fresh perspective for investigating protein changes linked to diseases. We utilize urine as a specific biomarker for early chronic mountain sickness (CMS) detection, as it is a simple-to-collect biological fluid. We collected urine samples from three groups: plains health, plateau health and CMS. Using DIA's proteomic approach, we found differentially expressed proteins between these groups, which will be used as a basis for future studies to identify protein markers. Compared with the healthy plain population, 660 altering proteins were identified in plateau health, which performed the resistance to altitude response function by boosting substance metabolism and reducing immune stress function. Compared to the healthy plateau population, the CMS group had 140 different proteins identified, out of which 8 were potential biomarkers for CMS. Our study has suggested that CMS may be closely related to increased thyroid hormone levels, oxidative damage to the mitochondria, impaired cell detoxification function and inhibited hydrolase activity. SIGNIFICANCE: Our team has compiled a comprehensive dataset of urine proteomics for AMS disease. We successfully identified differentially expressed proteins between healthy and AMS groups using the DIA proteomic approach. We discovered that 660 proteins were altered in plateau health compared to the healthy plain population, resulting in a heightened resistance to altitude response function by boosting substance metabolism and reducing immune stress function. Additionally, we pinpointed 140 different proteins in the AMS group compared to the healthy plateau population, with 8 showing potential as biomarkers for AMS. Our findings suggest that the onset of AMS may be closely linked to increased thyroid hormone levels, oxidative damage to the mitochondria, impaired cell detoxification function and inhibited hydrolase activity.

Comprehensive analysis reveals key genes and environmental toxin exposures underlying treatment response in ulcerative colitis based on in-silico analysis and Mendelian randomization

BACKGROUND

UC is increasingly prevalent worldwide and represents a significant global disease burden. Although medical therapeutics are employed, they often fall short of being optimal, leaving patients struggling with treatment non-responsiveness and many related complications.

MATERIALS AND METHODS

The study utilized gene microarray data and clinical information from GEO. Gene enrichment and differential expression analyses were conducted using Metascape and Limma, respectively. Lasso Regression Algorithm was constructed using glmnet and heat maps were generated using pheatmap. ROC curves were used to assess diagnostic parameter capability, while XSum was employed to screen for small-molecule drugs exacerbating UC. Molecular docking was carried out using Autodock Vina. The study also performed Mendelian randomization analysis based on TwoSampleMR and used CTD to investigate the relationship between exposure to environmental chemical toxicants and UC therapy responsiveness.

RESULTS

Six genes (ELL2, DAPP1, SAMD9L, CD38, IGSF6, and LYN) were found to be significantly overexpressed in UC patient samples that did not respond to multiple therapies. Lasso analysis identified ELL2 and DAPP1 as key genes influencing UC treatment response. Both genes accurately predicted intestinal inflammation in UC and impacted the immunological infiltration status. Clofibrate showed therapeutic potential for UC by binding to ELL2 and DAPP1 proteins. The study also reviews environmental toxins and drug exposures that could impact UC progression.

CONCLUSIONS

We used microarray technology to identify DAPP1 and ELL2 as key genes that impact UC treatment response and inflammatory progression. Clofibrate was identified as a promising UC treatment. Our review also highlights the impact of environmental toxins on UC treatment response, providing valuable insights for personalized clinical management.

The effect of chronic intermittent hypobaric hypoxia improving liver damage in metabolic syndrome rats through ferritinophagy

Studies have confirmed that hepatic iron overload is one of the important factors causing liver damage in the metabolic syndrome (MS). As a special form of autophagy, ferritinophagy is involved in the regulation of iron metabolism. Our previous studies have shown that chronic intermittent hypobaric hypoxia (CIHH) can improve the iron metabolism disorder. The aim of this study was to investigate how CIHH improves liver damage through ferritinophagy in MS rats. Male Sprague-Dawley rats aged 8-10 weeks were randomly divided into four groups: control (CON), CIHH (exposed to hypoxia at a simulated altitude of 5000 m for 28 days, 6 h daily), MS model (induced by a 16-week high-fat diet and 10% fructose water feeding), and MS + CIHH (exposed to CIHH after a 16-week MS inducement) groups. Liver index, liver function, iron content, tissue morphology, oxidative stress, ferritinophagy, ferroptosis, and iron metabolism-related protein expression were measured, and the ferritinophagy flux in the liver was further analyzed. Compared with CON rats, MS rats had an increased liver index, damaged liver tissue and function, increased iron content and iron deposition, disrupted iron metabolism, significantly increased oxidative stress indicators in the liver, significantly upregulated expression of ferroptosis-related proteins, and downregulated expression of nuclear receptor coactivator 4 (NCOA4) and ferritinophagy flux. After CIHH treatment, the degree of liver damage and various abnormal indicators in MS rats were significantly improved. CIHH may improve liver damage by promoting NCOA4-mediated ferritinophagy, reducing iron overload and oxidative stress, and thereby alleviating ferroptosis in MS rats.

The Importance of Thioredoxin-1 in Health and Disease

Thioredoxin-1 (Trx-1) is a multifunctional protein ubiquitously found in the human body. Trx-1 plays an important role in various cellular functions such as maintenance of redox homeostasis, proliferation, and DNA synthesis, but also modulation of transcription factors and control of cell death. Thus, Trx-1 is one of the most important proteins for proper cell and organ function. Therefore, modulation of Trx gene expression or modulation of Trx activity by various mechanisms, including post-translational modifications or protein-protein interactions, could cause a transition from the physiological state of cells and organs to various pathologies such as cancer, and neurodegenerative and cardiovascular diseases. In this review, we not only discuss the current knowledge of Trx in health and disease, but also highlight its potential function as a biomarker.

Molecular Mechanisms of High-Altitude Acclimatization

High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.

Proteomic and clinical biomarkers for acute mountain sickness in a longitudinal cohort

Ascending to high-altitude by non-high-altitude natives is a well-suited model for studying acclimatization to extreme environments. Acute mountain sickness (AMS) is frequently experienced by visitors. The diagnosis of AMS mainly depends on a self-questionnaire, revealing the need for reliable biomarkers for AMS. Here, we profiled 22 AMS symptom phenotypes, 65 clinical indexes, and plasma proteomic profiles of AMS via a combination of proximity extension assay and multiple reaction monitoring of a longitudinal cohort of 53 individuals. We quantified 1069 proteins and validated 102 proteins. Via differential analysis, machine learning, and functional association analyses. We found and validated that RET played an important role in the pathogenesis of AMS. With high-accuracies (AUCs > 0.9) of XGBoost-based models, we prioritized ADAM15, PHGDH, and TRAF2 as protective, predictive, and diagnostic biomarkers, respectively. Our findings shed light on the precision medicine for AMS and the understanding of acclimatization to high-altitude environments.

Oxidative Stress and Diseases Associated with High-Altitude Exposure

Several diseases associated with high-altitude exposure affect unacclimated individuals. These diseases include acute mountain sickness (AMS), high-altitude cerebral edema (HACE), high-altitude pulmonary edema (HAPE), chronic mountain sickness (CMS), and, notably, high-altitude pulmonary hypertension (HAPH), which can eventually lead to right ventricle hypertrophy and heart failure. The development of these pathologies involves different molecules and molecular pathways that might be related to oxidative stress. Studies have shown that acute, intermittent, and chronic exposure to hypobaric hypoxia induce oxidative stress, causing alterations to molecular pathways and cellular components (lipids, proteins, and DNA). Therefore, the aim of this review is to discuss the oxidative molecules and pathways involved in the development of high-altitude diseases. In summary, all high-altitude pathologies are related to oxidative stress, as indicated by increases in the malondialdehyde (MDA) biomarker and decreases in superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant activity. In addition, in CMS, the levels of 8-iso-PGF2α and H₂O₂ are increased, and evidence strongly indicates an increase in Nox4 activity in HAPH. Therefore, antioxidant treatments seem to be a promising approach to mitigating high-altitude pathologies.

TMT-Based Plasma Proteomics Reveals Dyslipidemia Among Lowlanders During Prolonged Stay at High Altitudes

Acute exposure to high altitude perturbs physiological parameters and induces an array of molecular changes in healthy lowlanders. However, activation of compensatory mechanisms and biological processes facilitates high altitude acclimatization. A large number of lowlanders stay at high altitude regions from weeks to months for work and professional commitments, and thus are vulnerable to altitude-associated disorders. Despite this, there is a scarcity of information for molecular changes associated with long-term stay at high altitudes. In the present study, we evaluated oxygen saturation (SpO₂), heart rate (HR), and systolic and diastolic blood pressure (SBP and DBP) of lowlanders after short- (7 days, HA-D7) and long-term (3 months, HA-D150) stay at high altitudes, and used TMT-based proteomics studies to decipher plasma proteome alterations. We observed improvements in SpO₂ levels after prolonged stay, while HR, SBP, and DBP remained elevated as compared with short-term stay. Plasma proteomics studies revealed higher levels of apolipoproteins APOB, APOCI, APOCIII, APOE, and APOL, and carbonic anhydrases (CA1 and CA2) during hypoxia exposure. Biological network analysis also identified profound alterations in lipoprotein-associated pathways like plasma lipoprotein assembly, VLDL clearance, chylomicron assembly, chylomicron remodeling, plasma lipoprotein clearance, and chylomicron clearance. In corroboration, lipid profiling revealed higher levels of total cholesterol (TC), triglycerides (TGs), low-density lipoprotein (LDL) for HA-D150 whereas high density lipoproteins (HDL) levels were lower as compared with HA-D7 and sea-level indicating dyslipidemia. We also observed higher levels of proinflammatory cytokines IL-6, TNFα, and CRP for HA-D150 along with oxidized LDL (oxLDL), suggesting vascular inflammation and proartherogenic propensity. These results demonstrate that long-term stay at high altitudes exacerbates dyslipidemia and associated disorders.