Hypoxia and Inflammation: Insights From High-Altitude Physiology

Acute mountain sickness prediction: a concerto of multidimensional phenotypic data and machine learning strategies in the framework of predictive, preventive, and personalized medicine

Background

Acute mountain sickness (AMS) is a self-limiting illness, involving a complex series of physiological responses to rapid ascent to high altitudes, where the body is exposed to lower oxygen levels (hypoxia) and changes in atmospheric pressure. AMS is the mildest and most common form of altitude sickness; however, without adequate preparation and adherence to ascent guidelines, it can progress to life-threatening conditions.

Aims

Due to the multi-factorial predisposition of AMS among individuals, identifying AMS biomarkers before high altitude exposure from multiple dimensions (e.g., clinical, metabolic, and proteomic markers) and integrating them to build an AMS predictive model enables early diagnosis and personalized interventions, which allows targeted allocation of medical resources, such as prophylactic medications (e.g., acetazolamide) and supplemental oxygen, to those who need them most and prevention of unnecessary complications. Consequently, predicting AMS utilizing biomarkers from multidimensional phenotypic data before high-altitude exposure is essential for the paradigm change in high-altitude medical research from currently applied reactive services to the cost-effective predictive, preventive, and personalized medicine (PPPM/3PM) in primary (reversible damage to health and targeted protection against health-to-disease transition) and secondary (personalized protection against disease progression) care.

Methods

To this end, this study recruited 83 Han Chinese male volunteers and obtained clinical, proteomic, and metabolomic profiles for analysis before they ascended to high altitudes. The Mann-Whitney U test was used to identify clinical features distinguishing AMS from non-AMS. The proteomic and metabolomic features were concatenated and clustered to find co-expression modules associated with AMS. A machine learning model, Mutual Information-radial kernel-based Support Vector Machine-Recursive Feature Elimination (MI-radialSVM-RFE) was employed for biomarkers selection and AMS prediction. A molecular docking technique was used to select molecular biomarkers that can bind with Traditional Chinese Medicine (TCM) ingredients.

Results

Among 83 participants, 66 were selected for detailed analysis after quality control steps. Six protein-metabolite co-expression modules were identified as significantly associated with AMS. The MI-radialSVM-RFE model selected 12 biomarkers (two clinical features: systolic blood pressure (SBP) and peak expiratory flow (PEF); six proteins: Acyl-CoA synthetase long-chain family member 4 (ACSL4), immunoglobulin kappa variable 1D-16 (IGKV1D-16), coagulation factor XIII B subunit (F13B), prosaposin (PSAP), poliovirus receptor (PVR), and multimerin-2 (MMRN2); and four metabolites: 2-Methyl-1,3-cyclohexadiene, calcitriol, 4-Acetamido-2-amino-6-nitrotoluene, and 20-Hydroxy-PGE2) for the AMS prediction model. The model exhibited excellent predictive performance in both training (n = 66) and validating cohorts (n = 24) with AUCs of 0.97 and 0.94, respectively. Additionally, molecular docking analysis suggested PSAP and ACSL4 proteins as potential molecular targets for AMS prevention.

Conclusion and expert recommendations

This study advances high-altitude medicine by developing a predictive model for AMS using clinical, proteomic, and metabolomic data. The identified biomarkers linked to energy metabolism, immune response, and vascular regulation offer insights into AMS mechanisms. High-altitude predictive approaches should focus on implementing biomarker-driven risk screening using clinical, proteomic, and metabolomic data to identify high-risk individuals before high-altitude exposure. Preventive measures should prioritize pre-acclimatization protocols, tailored nutritional strategies and interventions guided by biomarker profiles, and lifestyle adjustments, such as maintaining mitochondrial health through proper nutritional strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-025-00404-9.

Flavonoids and their role in oxidative stress, inflammation, and human diseases

Oxidative stress and chronic inflammation are important drivers in the pathogenesis and progression of many chronic diseases, such as cancers of the breast, kidney, lung, and others, autoimmune diseases (rheumatoid arthritis), cardiovascular diseases (hypertension, atherosclerosis, arrhythmia), neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease), mental disorders (depression, schizophrenia, bipolar disorder), gastrointestinal disorders (inflammatory bowel disease, colorectal cancer), and other disorders. With the increasing demand for less toxic and more tolerable therapies, flavonoids have the potential to effectively modulate the responsiveness to conventional therapy and radiotherapy. Flavonoids are polyphenolic compounds found in fruits, vegetables, grains, and plant-derived beverages. Six of the twelve structurally different flavonoid subgroups are of dietary significance and include anthocyanidins (e.g. pelargonidin, cyanidin), flavan-3-ols (e.g. epicatechin, epigallocatechin), flavonols (e.g. quercetin, kaempferol), flavones (e.g. luteolin, baicalein), flavanones (e.g. hesperetin, naringenin), and isoflavones (daidzein, genistein). The health benefits of flavonoids are related to their structural characteristics, such as the number and position of hydroxyl groups and the presence of C2C3 double bonds, which predetermine their ability to chelate metal ions, terminate ROS (e.g. hydroxyl radicals formed by the Fenton reaction), and interact with biological targets to trigger a biological response. Based on these structural characteristics, flavonoids can exert both antioxidant or prooxidant properties, modulate the activity of ROS-scavenging enzymes and the expression and activation of proinflammatory cytokines (e.g., interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α)), induce apoptosis and autophagy, and target key signaling pathways, such as the nuclear factor erythroid 2-related factor 2 (Nrf2) and Bcl-2 family of proteins. This review aims to briefly discuss the mutually interconnected aspects of oxidative and inflammatory mechanisms, such as lipid peroxidation, protein oxidation, DNA damage, and the mechanism and resolution of inflammation. The major part of this article discusses the role of flavonoids in alleviating oxidative stress and inflammation, two common components of many human diseases. The results of epidemiological studies on flavonoids are also presented.

High-fat diet-induced osteoporosis in mice under hypoxic conditions

In the context of global aging, osteoporosis has emerged as a significant public health concern, with a relatively high prevalence observed in plateau regions. This study aimed to investigate the effects and underlying mechanisms of high-fat diet (HFD) and hypoxic conditions on bone metabolism in mice. The mice were subjected to different dietary regimens (a HFD versus a normal diet) and placed in a hypoxic environment. This study explored relevant mechanisms through comprehensive assessments, including body and bone morphological indices, pathological examinations, biochemical analyses, evaluation of gut microbiota diversity, and metabolomics approaches. The results indicated that, compared with those in the control group, the body weight, Lee's index, body mass index (BMI), and body fat percentage of the HFD-fed group were significantly greater. Additionally, the femoral microstructure was compromised, bone metabolic markers were disrupted, inflammatory responses were heightened, gut microbiota diversity was altered, and specific intestinal metabolites such as Anserine were downregulated, whereas L-carnosine was upregulated. Spearman correlation analysis and network visualization elucidated the multifactorial influence mechanism of a HFD on bone metabolism under hypoxic conditions. These factors interconnect to form a complex network that drives osteoporosis development. Notably, L-carnosine occupies a central position within this network, serving as a key hub for interactions among various factors. Under the dual stressors of hypoxia and a HFD, this network becomes imbalanced, leading to bone metabolic disorders and osteoporosis. This study provides insights into the multifactorial mechanisms of osteoporosis induced by a HFD and hypoxia in mice, offering a foundation for subsequent research and preventive strategies for osteoporosis in plateau areas.

Urine metabolite profiling in Indian males exposed to high-altitude: a longitudinal pilot study

People who visit high-altitude for research and development work, pilgrimage, recreational purposes and deployments are exposed to different environmental conditions such as low temperature and atmospheric pressure, leading to hypoxia, high radiation, dry air, and non-availability of fresh food and vegetables. These environmental stressors have significant physiological effects on the human body. Among these challenges, hypobaric hypoxia at high-altitude affects aerobic metabolism and thereby reduces the supply of metabolic energy. Metabolic alterations may further lead to extreme environment related maladaptation as evidenced by alterations in the levels of metabolites and metabolic pathways. To investigate the variation in the metabolite profile, urine samples were collected from 16 individuals at baseline (BL, 210 m) and high-altitude (HA, 4200 m). Untargeted urinary metabolic profiling was performed by liquid chromatography-mass spectrometry (LC-MS) in conjunction with statistical analysis. Univariate and multivariate statistical analyses revealed 33 differentially abundant metabolites based on fold change, VIP score and p value. These distinct metabolites were primarily associated with pathways related to phenylalanine, tyrosine and tryptophan biosynthesis; metabolism of phenylalanine, biotin, tyrosine, cysteine and methionine along with alanine, aspartate and glutamate metabolism. Thes pathways are also linked with pentose and glucuronate interconversions, citrate cycle, vitamin B6 and porphyrin metabolism. Furthermore, receiver operating characteristic curve analysis detected five metabolites namely, 2-Tetrahydrothiopheneacetic acid, 1-Benzyl-7,8-dimethoxy-3-phenyl-3H-pyrazolo [3,4-c] isoquinoline, Abietin, 4,4'-Thiobis-2-butanone, and Hydroxyisovaleroyl carnitine with high range of sensitivity and specificity. In summary, this longitudinal study demonstrated novel metabolic variations in humans exposed to high-altitude, utilising the potential of LC-MS based metabolomics. Thus, the present findings shed light on the impact of hypoxic exposure on metabolic adaptation and provide a better understanding about the pathophysiological mechanisms underlying high-altitude illnesses correlated to tissue hypoxia.

The acute effects of simulated hypoxic training at different altitudes on oxidative stress and muscle damage in elite long-distance runners

Background

Understanding the impact of altitude on muscle damage and oxidative stress is essential for optimizing training and recovery strategies for athletes exposed to high-altitude conditions. Therefore, this study aimed to investigate the effects of acute exercise at different altitudes on oxidative stress and muscle damage.

Methods

A total of twelve elite long-distance runners (mean age: 20.3 ± 1.5 years) from different branches participated in the study. The exercise protocol was the Bruce submaximal treadmill exercise test, which was conducted under three simulated hypoxic conditions (at 1,700 m, 2,450 m, and 3,200 m) and one normoxic condition (sea level). All measurements took place at the same time of the day. After the exercise protocol, 5 ml venous blood samples were taken from the participants, while heart rate and oxygen saturation were monitored at the 3rd, 6th, 9th, and 12th minutes during the exercise.

Results

Significant altitude-dependent variations were observed in oxidative stress markers, with total oxidant status (TOS) (p = 0.017) and malondialdehyde (MDA) (p < 0.001) levels increasing at higher altitudes, while total antioxidant status (TAS) (p < 0.001) exhibited an elevation and oxidative stress index (OSI) (p < 0.001) demonstrated a decline as altitude increased. However, no significant difference was found in creatine kinase (CK, p = 0.059) levels. Additionally, there were significant differences in the oxygen saturation measurement taken at the 3rd (p < 0.001), 6th (p < 0.001), 9th (p < 0.001), and 12th (p < 0.001), minutes following the exercise session. There was no difference in the pulse measurement taken at the 3rd and 12th minutes, but a difference was observed at the 6th and 9th minutes post-exercise (p < 0.01).

Conclusions

In conclusion, the study determined that endurance exercises performed under simulated normobaric hypoxia at different altitudes increased TAS and reduced OSI in elite long-distance runners. The increase in TAS and the reduction in OSI were more pronounced at higher altitudes, particularly at 2,450 m and 3,200 m, compared to sea level. These findings highlight the need for altitude-specific training and recovery strategies to minimize oxidative stress and muscle damage in athletes.

Nonhypermutator Cancers Access Driver Mutations Through Reversals in Germline Mutational Bias

Cancer is an evolutionary disease driven by mutations in asexually reproducing somatic cells. In asexual microbes, bias reversals in the mutation spectrum can speed adaptation by increasing access to previously undersampled beneficial mutations. By analyzing tumors from 20 tissues, along with normal tissue and the germline, we demonstrate this effect in cancer. Nonhypermutated tumors reverse the germline mutation bias and have consistent spectra across tissues. These spectra changes carry the signature of hypoxia, and they facilitate positive selection in cancer genes. Hypermutated and nonhypermutated tumors thus acquire driver mutations differently: hypermutated tumors by higher mutation rates and nonhypermutated tumors by changing the mutation spectrum to reverse the germline mutation bias.

In vitro study: HIF-1α-dependent glycolysis enhances NETosis in hypoxic conditions

Background

Hypoxia plays a pivotal role in modulating immune responses, especially in neutrophils, which are essential components of the innate immune system. Hypoxia-inducible factor (HIF)-1α, a key transcription factor in hypoxic adaptation, regulates cellular metabolism and inflammatory responses. However, the impact of HIF-1α-dependent glycolysis on the formation of neutrophil extracellular traps (known as NETosis) under hypoxic conditions remains unclear.

Methods

We employed two established neutrophil models, neutrophils isolated from human whole blood and DMSO-induced dHL-60 cells, to explore the role of HIF-1α in regulating glycolysis and its influence on NETosis under hypoxic conditions. We utilized western blotting, immunofluorescence staining, ELISA, and flow cytometry to evaluate the expression of key glycolytic enzymes and NETosis markers under hypoxia. Additionally, the effects of inhibiting HIF-1α with LW6 and blocking the glycolytic pathway with Bay-876 were investigated.

Results

HIF-1α-dependent glycolysis, through the upregulation of key glycolytic enzymes, significantly enhances NETosis under hypoxic conditions. Pharmacological inhibition of HIF-1α with LW6 and glycolytic blockade with Bay-876 markedly reduced NETosis, underscoring the crucial role of metabolic reprogramming in neutrophil function during hypoxia.

Conclusion

This study provides novel insights into the interplay between metabolic reprogramming and NETosis in response to hypoxic stress. We identify HIF-1α-dependent glycolysis as a key driver of NETs formation, advancing our understanding of the mechanisms underlying hypoxia-related inflammatory diseases. These findings also suggest that targeting metabolic pathways may offer potential therapeutic strategies for modulating immune responses in hypoxia-associated disorders.

GCH1 contributes to high-altitude adaptation in Tibetans by regulating blood nitric oxide

Nitric oxide (NO) is a key vasodilator that regulates vascular pressure and blood flow. Tibetans have developed a "blunted" mechanism for regulating NO levels at high altitude, with GTP cyclohydrolase 1 (GCH1) identified as a key candidate gene. Here, we present comprehensive genetic and functional analyses of GCH1, which exhibits strong Darwinian positive selection in Tibetans. We show that Tibetan-enriched GCH1 variants down-regulate its expression in the blood of Tibetans. Based on this observation, we generate the heterozygous Gch1 knockout (Gch1+/-) mouse model to simulate its downregulation in Tibetans. We find that under prolonged hypoxia, the Gch1+/- mice have relatively higher blood NO and blood oxygen saturation levels compared to the wild-type (WT) controls, providing better oxygen supplies to the cardiovascular and pulmonary systems. Markedly, hypoxia-induced cardiac hypertrophy and pulmonary remodeling are significantly attenuated in the Gch1+/- mice compared with the WT controls, likely due to the adaptive changes in molecular regulations related to metabolism, inflammation, circadian rhythm, extracellular matrix, and oxidative stress. This study sheds light on the role of GCH1 in regulating blood NO, contributing to the physiological adaptation of the cardiovascular and pulmonary systems in Tibetans at high altitude.

Hypoxia-induced Wnt5a-secreting fibroblasts promote colon cancer progression

Wnt5a, a representative Wnt ligand that activates the β-catenin-independent pathway, has been shown to promote tumorigenesis. However, it is unclear where Wnt5a is produced and how it affects colon cancer aggressiveness. In this study, we demonstrate that Wnt5a is expressed in fibroblasts near the luminal side of the tumor, and its depletion suppresses mouse colon cancer formation. To characterize the specific fibroblast subtype, a meta-analysis of human and mouse colon fibroblast single-cell RNA-seq data is performed. The results show that Wnt5a is expressed in hypoxia-induced inflammatory fibroblast (InfFib), accompanied by the activation of HIF2. Moreover, Wnt5a maintains InfFib through the suppression of angiogenesis mediated by soluble VEGF receptor1 (Flt1) secretion from endothelial cells, thereby inducing further hypoxia. InfFib also produces epiregulin, which promotes colon cancer growth. Here, we show that Wnt5a acts on endothelial cells, inducing a hypoxic environment that maintains InfFib, thereby contributing to colon cancer progression through InfFib.

Neurological Manifestations Associated with Exercise at Altitude

PURPOSE OF REVIEW

The effects that exercise at altitude has on the neurological system are diverse and still not well studied, and range from metabolic adaptations to modification of cerebral blood flow and neurotransmitters. In this review we summarise changes with exercise intensity, the implications of ascent, cognitive impairment, psychosis-like symptoms, the role of exercise in the development and prevention of AMS, and use of free radical scavengers to enhance sports performance and acclimatization.

RECENT FINDINGS

We discuss the impact of oxidative stress in hypobaric hypoxia and reactive oxygen species (ROS) production and its consequences, with special focus on exercise at altitude. Finally we consider how moderate intensity exercise could help prevent AMS, and the necessity of research on high intensity exercise with elevated rate of ascent, the development of specific tools of cognitive assessment, and the role of free-radical scavengers in the prevention of AMS and neurological symptoms.

Tissue remodeling during high-altitude pulmonary edema in rats: Biochemical and histomorphological analysis

High altitude characterized by the low partial pressure of the oxygen is a life-threatening condition that contributes to the development of acute pulmonary edema and hypoxic lung injury. In this study, we aimed to investigate the contribution of some inflammatory and oxidative stress markers along with antioxidant system enzymes in the pathogenesis of HAPE (high-altitude pulmonary edema) formation. We incorporated the study on 42 male rats to unravel the role of mast cells (MCs) and TNF-α in the lung after the effect of acute hypobaric hypoxia. The HAPE model was mimicked with a decompression chamber at the altitude of 7620 m for a duration of 24 h. The study reveals various histological changes in the rat's lung exposed to hypoxia that was accompanied by immense inflammatory cell infiltration, edema, hemorrhages, and fibrosis. Moreover, the wet weight of the lungs and the arginase level was also increased (p < 0.05). While the NO level was shown to be diminished (p < 0.01). Acute hypobaric hypoxia also caused MC degranulation and increased TNF-α-expression in the lung, which considerably promoted inflammation after hypoxic damage. However, the antioxidant system was weakened following the decreased activity of SOD and catalase. Moreover, the cell energy metabolism was also altered accompanied by an elevated level of LDH. Our findings suggest that the NO and arginase and antioxidant system enzymes along with TNF-α and MCs may play a role in HAPE pathogenesis and contribute to the alveolar-capillary barrier disruption that leads to edema formation. Uncovering the pathological mechanisms of this disease would provide valuable information about the molecular basis of pulmonary edema development and therefore used for further preventive tools to manage the risks posed by high altitude-induced lung damage.

Hypoxia-Induced Inflammation in In Vitro Model of Human Blood-Brain Barrier: Modulatory Effects of the Olfactory Ensheathing Cell-Conditioned Medium

Hypoxia compromises the integrity of the blood-brain barrier (BBB) and increases its permeability, thereby inducing inflammation. Olfactory ensheathing cells (OECs) garnered considerable interest due to their neuroregenerative and anti-inflammatory properties. Here, we aimed to investigate the potential modulatory effects of OEC-conditioned medium (OEC-CM) on the response of human brain microvascular endothelial cells (HBMECs), constituting the BBB, when exposed to hypoxia. HBMECs were utilized to establish the in vitro BBB model. OECs were isolated from mouse olfactory bulbs, and OEC-CM was collected after 48 h of culture. The effect of OEC-CM treatment on the HBMEC viability was evaluated under both normoxic and hypoxic conditions at 6 h, 24 h, and 30 h. Western blot and immunostaining techniques were employed to assess NF-κB/phospho-NF-κB expression. HIF-1α, VEGF-A, and cPLA2 mRNA expression levels were quantified using digital PCR. ELISA assays were performed to measure PGE2, VEGF-A, IL-8 secretion, and cPLA2 specific activity. The in vitro formation of HBMEC capillary-like structures was examined using a three-dimensional matrix system. OEC-CM attenuated pro-inflammatory responses and mitigated the HIF-1α/VEGFA signaling pathway activation in HBMECs under hypoxic condition. Hypoxia-induced damage of the BBB can be mitigated by novel therapeutic strategies harnessing OEC potential.

Hypoxia signaling in cancer: HIF-1α stimulated by COVID-19 can lead to cancer progression and chemo-resistance in oral squamous cell carcinoma (OSCC)

The potential implications of Coronavirus disease-2019 (COVID-19) on oral squamous cell carcinoma (OSCC) development, chemo-resistance, tumor recurrence, and patient outcomes are explored, emphasizing the urgent need for tailored therapeutic strategies to mitigate these risks. The role of hypoxia-inducible factor 1-alpha (HIF-1α) in OSCC studies has highlighted HIF-1α as a crucial prognostic marker in OSCC, with implications for disease prognosis and patient survival. Its overexpression has been linked to aggressive subtypes in early OSCC stages, indicating its significance as an early biomarker for disease progression. Moreover, dysplastic lesions with heightened HIF-1α expression exhibit a greater propensity for malignant transformation, underscoring its role in early oral carcinogenesis. Cancer patients, including those with OSCC, face an elevated risk of severe COVID-19 complications, which may further impact cancer progression and treatment outcomes. Understanding the interplay between COVID-19 infection, HIF-1α activation, and OSCC pathogenesis is crucial for enhancing clinical management strategies. So, insights from this review shed light on the significance of HIF-1α in OSCC tumorigenesis, metastasis formation, and patient prognosis. The review underscores the need for further research to elucidate the precise mechanisms through which HIF-1α modulates cancer progression and chemo-resistance in the context of COVID-19 infection. Such knowledge is essential for developing targeted therapeutic interventions to improve outcomes for OSCC patients.

Estrogen via GPER downregulated HIF-1a and MIF expression, attenuated cardiac arrhythmias, and myocardial inflammation during hypobaric hypoxia

BACKGROUND

The human body is highly dependent on adequate oxygenation of the cellular space for physiologic homeostasis mediation. The insufficient oxygenation of the cellular space leads to hypoxia. Hypobaric hypoxia (HH) is the reduction in oxygen partial pressure and atmospheric pressure during ascent to high altitudes. This state induces a maladaptive response. Women and how hormones like estrogen influence hypoxia have not been explored with most research being conducted on males. In this study, we investigated the effects of estrogen and GPER on HIF-1a and MIF expression, cardiac arrhythmias, and inflammation during hypobaric hypoxia.

METHODS

Ovariectomy and SHAM operations were done on FVB wild-type (WT) female mice. 2 weeks after the operation, the mice were treated with estrogen (40 mg/kg) as a therapeutic intervention and placed in a hypoxic chamber at an altitude of 6000 m for 7 days. Cardiac electrical activity was assessed using electrocardiography. Alterations in protein expression, inflammatory, and GPER pathways were investigated using western blotting, ELISA, and immunofluorescence. Histological assessment was performed using Masson's trichrome staining. Peritoneal macrophages were isolated for in vitro study.

RESULTS

Under hypobaric hypoxia (HH), the ovariectomized (OVX) group showed increased macrophage migration inhibitory factor (MIF) and hypoxia-inducible factor-1 alpha (HIF-1α) expression. In contrast, these factors were downregulated in the estrogen-treated and control groups. HH also caused cardiac inflammation and fibrosis, especially in the OVX + HH group, which had elevated proinflammatory cytokines (IL-1β, IL-6, TNF-α) and decreased anti-inflammatory cytokines (TGF-β, IL-10). Inhibition with G15 (a GPER antagonist) increased MIF and HIF-1α, whereas activation with G1 (a GPER agonist) decreased their expression, highlighting GPER's crucial role in regulating MIF during HH.

CONCLUSION

Estrogen regulates HIF-1α and MIF expression through the GPER during hypobaric hypoxia, suggesting a potential therapeutic pathway to mitigate maladaptive responses during high-altitude ascent.

Oxygen metabolism abnormalities and high-altitude cerebral edema

Hypobaric hypoxia is widely recognized as a prominent risk factor for high-altitude cerebral edema (HACE), which contributes to the exacerbation of multiple pathological mechanisms, including oxidative stress, mitochondrial dysfunction, disruption of blood-;brain barrier integrity, neuroinflammation, and neuronal apoptosis. Among these mechanisms, abnormalities in oxygen metabolism, including hypoxia, oxidative stress, and mitochondrial dysfunction, play pivotal roles in the pathophysiology of HACE. In this review, our objective is to enhance our comprehension of the underlying molecular mechanisms implicated in HACE by investigating the potential involvement of oxygen metabolism. Addressing aberrations in oxygen metabolism holds promise for providing innovative therapeutic strategies for managing HACE.

Miniature chicken ileal explant culture to investigate the inflammatory response induced by pathogen-associated molecular patterns

Gastrointestinal inflammation leads to maldigestion and systemic diseases in poultry. To tackle the problem of the industry and to search for therapeutic candidates in vitro models are inevitable. Both immersion and air-liquid interface explant models are available, although there is limited information on the size-dependent applicability and response to different pathogen-associated molecular patterns (PAMPs) in the case of these model systems. The study aimed to compare the morphology and viability of miniature chicken gut explant cultures obtained with a biopsy punch to examine the size-dependent change over time. To verify the applicability of the model, pathogen-associated molecular patterns (PAMPs): flagellin, lipoteichoic acid (LTA) and polyinosinic polycytidylic acid (poly I:C) were applied to induce inflammation. The 2 mm diameter explants showed a decrease in metabolic activity measured by CCK-8 assay after 12 h and a significantly higher extracellular lactate dehydrogenase activity indicating cellular damage compared to the 1 mm explants, supported by histological differences after 24 h of culturing. After 12 h of incubation, the 1.5 mm explants retained columnar epithelial lining with moderate damage of the lamina propria (H&E and pan-cytokeratin staining). Exposure to 100 μg/mL poly I:C reduced the metabolic activity of the 1.5 mm explants. LTA and poly I:C increased IFN-γ concentration at both applied doses and IFN-α concentration was elevated by 50 μg/mL poly I:C treatment. Flagellin administration raised IL-2, IL-6, and RANTES levels, while higher LTA and poly I:C concentrations increased the IFN-γ/IL-10 ratio. According to the observations, the viability and integrity of the explants decreases with their size. After 12 h, the 1.5 mm diameter miniature chicken ileal explant stimulated with PAMPs can be an appropriate model to mimic diseases involving tissue damage and inflammation.

Adaptation of the Spalax galili transcriptome to hypoxia may underlie the complex phenotype featuring longevity and cancer resistance

In the subterranean rodent (Nanno)spalax galili, evolutionary adaptation to hypoxia is correlated with longevity and tumor resistance. Adapted gene-regulatory networks of Spalax might pinpoint strategies to maintain health in humans. Comparing liver, kidney and spleen transcriptome data from Spalax and rat at hypoxia and normoxia, we identified differentially expressed gene pathways common to multiple organs in both species. Body-wide interspecies differences affected processes like cell death, antioxidant defense, DNA repair, energy metabolism, immune response and angiogenesis, which may play a crucial role in Spalax's adaptation to environmental hypoxia. In all organs, transcription of genes for genome stability maintenance and DNA repair was elevated in Spalax versus rat, accompanied by lower expression of aerobic energy metabolism and proinflammatory genes. These transcriptomic changes might account for the extraordinary lifespan of Spalax and its cancer resistance. The identified gene networks present candidates for further investigating the molecular basis underlying the complex Spalax phenotype.

Integrative analysis reveals the multilateral inflammatory mechanisms of CD14 monocytes in gout

OBJECTIVES

Gout, prevalent inflammatory arthritis caused by urate crystal deposition, involves immune cell activation, yet the precise role of CD14 monocytes in initiating the inflammatory response is poorly understood. This study aimed to characterise the molecular and cellular landscape of CD14 monocytes in gout using single-cell transcriptomic analysis.

METHODS

Single-cell RNA sequencing was performed on peripheral blood mononuclear cells from 8 gout patients and 6 age- and sex-matched healthy controls. The findings were validated using publicly available datasets. Differential gene expression and pathway enrichment analyses were conducted to identify gout's key molecular regulators and cellular subclusters.

RESULTS

At the molecular level, we identified hypoxia-related pathways, including HIF1A, as key regulators of interleukin-1β production in CD14 monocytes in gout. We also observed significant downregulation of CLEC12A across all CD14 monocyte subclusters. At the cellular level, an S100Ahigh CD14 monocyte subcluster, characterized by high expression of S100A8/A9/A12 and linked to inflammatory and metabolic pathways, was found to drive NLRP3 and CLEC7A inflammasome activation, as well as prostaglandin secretion. In vitro stimulation with monosodium urate crystals revealed that the differentially expressed genes were enriched in S100Ahigh monocytes, highlighting the synergistic role of these pathways in driving gout inflammation. Additionally, gout genome-wide association study-prioritised genes underscored the role of fatty acid metabolism in inflammation, promoting prostaglandin secretion from S100Ahigh monocytes.

CONCLUSIONS

These findings provide new insights into the role of CD14 monocytes in gout pathogenesis, particularly the contribution of hypoxia and fatty acid metabolism pathways, and suggest potential therapeutic targets for precision medicine in gout treatment.

Alternatively spliced NFKB1 transcripts enriched in Andean Aymara modulate inflammation, HIF and hemoglobin

The molecular basis of increased hemoglobin in Andean Aymara highlanders is unknown. We conducted an integrative analysis of whole-genome-sequencing and granulocytes transcriptomics from Aymara and Europeans in Bolivia to explore genetic basis of the Aymara high hemoglobin. Differentially expressed and spliced genes in Aymaras were associated with inflammatory and hypoxia-related pathways. We identified transcripts with 4th or 5th exon skipping of NFKB1 (AS-NFKB1), key part of NF-kB complex, and their splicing quantitative trait loci; these were increased in Aymaras. AS-NFKB1 transcripts correlated with both transcripts and protein levels of inflammatory and HIF-regulated genes, including hemoglobin. While overexpression of the AS-NFKB1 variant led to increased expression of inflammatory and HIF-targeted genes; under inflammatory stress, NF-kB protein translocation to the nucleus was attenuated, resulting in reduced expression of these genes. Our study reveals AS-NFKB1 splicing events correlating with increased hemoglobin in Aymara and their possible protective mechanisms against excessive inflammation.

The Role of Hypoxia in Longevity

Aging is marked by a progressive decrease in physiological function and reserve capacity, which results in increased susceptibility to diseases. Understanding the mechanisms of driving aging is crucial for extending health span and promoting human longevity. Hypoxia, marked by reduced oxygen availability, has emerged as a promising area of study within aging research. This review explores recent findings on the potential of oxygen restriction to promote healthy aging and extend lifespan. While the role of hypoxia-inducible factor 1 (HIF-1) in cellular responses to hypoxia is well-established, its impact on lifespan remains complex and context-dependent. Investigations in invertebrate models suggest a role for HIF-1 in longevity, while evidence in mammalian models is limited. Hypoxia extends the lifespan independent of dietary restriction (DR), a known intervention underlying longevity. However, both hypoxia and DR converge on common downstream effectors, such as forkhead box O (FOXO) and flavin-containing monooxygenase (FMOs) to modulate the lifespan. Further work is required to elucidate the molecular mechanisms underlying hypoxia-induced longevity and optimize clinical applications. Understanding the crosstalk between HIF-1 and other longevity-associated pathways is crucial for developing interventions to enhance lifespan and healthspan. Future studies may uncover novel therapeutic strategies to promote healthy aging and longevity in human populations.

Association of Polymorphism with Periodontitis and Salivary Levels of Hypoxia-Inducible Factor-1α

OBJECTIVE

 This investigation aims to investigate the association between HIF-1α genetic polymorphism and periodontitis and examine and contrast the levels of HIF-1α present in the saliva of subjects afflicted with periodontitis and in the control group. Additionally, this study aims to establish diagnostic proficiency of this biomarker in distinguishing between periodontal health and disease.

MATERIALS AND METHODS

 This study entailed the collection of venous blood samples and unstimulated saliva samples from a total of 160 participants, encompassing 80 individuals diagnosed with periodontitis and 80 periodontitis-free individuals. The periodontal parameters were evaluated, involving the measurement of clinical attachment loss, the probing pocket depth, and the bleeding on probing percentage. Subsequently, genetic analysis of HIF-1α using polymerase chain reaction (PCR) technique, DNA sequencing, and enzyme-linked immunosorbent assays was conducted.

RESULTS

 The genetic analysis of 352 bp of the HIF-1α gene revealed the presence of 66 single-nucleotide polymorphisms (SNPs) in control samples, whereas 78 SNPs were found in periodontitis sample. The nucleotide A was replaced with a C nucleotide at position 207 of the amplified PCR fragments. The homozygous AA pattern was predominant in the control group, with significant differences between the two groups. In contrast, the homozygous CC pattern was more dominant in the periodontitis group, with significant differences between the two groups. The analysis of Hardy-Weinberg equilibrium for the comparison between the observed and the expected genotypes showed significant differences between the observed and the expected values in the control and periodontitis groups, as well as the total sample. The highest mean values of the measured periodontal parameters were found in the periodontitis group (clinical attachment loss = 4.759, probing pocket depth = 4.050, and bleeding on probing = 30.950) with statistically significant differences between the groups. The periodontitis group showed significantly higher salivary HIF-1α levels compared to control group (p < 0.001). Besides, HIF-1α is a good biomarker in distinguishing between periodontal health and periodontitis.

CONCLUSION

 rs1951795 SNP of HIF-1α has no significant impact on the progression of periodontitis and the salivary level HIF-1α. Periodontitis results in a notable elevation in HIF-1α salivary levels, with an outstanding diagnostic ability to distinguish between periodontitis and periodontal health.

Multi-omics reveals immune response and metabolic profiles during high-altitude mountaineering

The physiological perturbations induced by high-altitude exposure in mountain climbers, manifesting as immunological and metabolic deviations, have been previously reported but are not fully understood. In this study, we obtain multi-omic profiles of climbers' blood samples, including single-cell transcriptomic analysis of 375,722 immune cells, and plasma metabolomics and lipidomics. Longitudinal analysis reveals dynamic immune response profiles, during the acclimatization period, characterized by the downregulation of inflammatory responses in myeloid cell subsets and by the enhancement of immune effector processes in cytotoxic CD8+ T, γδT, and CD16+ natural killer cells. In contrast, during extreme-altitude mountaineering, the activation of inflammatory responses and impairment of immune effector function are observed, concomitant with an increased cellular response to hypoxia and oxidative stress pathways. Furthermore, glycolysis and antioxidant gene expression are upregulated during extreme-altitude mountaineering. Plasma metabolic analysis reveals significant alterations, involving enhanced glutamine and fatty acid metabolism.

Neurological Biomarker Profiles in Royal Canadian Air Force (RCAF) Pilots and Aircrew

BACKGROUND/OBJECTIVES

Military aviators can be exposed to extreme physiological stressors, including decompression stress, G-forces, as well as intermittent hypoxia and/or hyperoxia, which may contribute to neurobiological dysfunction/damage. This study aimed to investigate the levels of neurological biomarkers in military aviators to assess the potential risk of long-term brain injury and neurodegeneration.

METHODS

This cross-sectional study involved 48 Canadian Armed Forces (CAF) aviators and 48 non-aviator CAF controls. Plasma samples were analyzed for biomarkers of glial activation (GFAP), axonal damage (NF-L, pNF-H), oxidative stress (PRDX-6), and neurodegeneration (T-tau), along with S100b, NSE, and UCHL-1. The biomarker concentrations were quantified using multiplexed immunoassays.

RESULTS

The aviators exhibited significantly elevated levels of GFAP, NF-L, PRDX-6, and T-tau compared to the CAF controls (p < 0.001), indicating increased glial activation, axonal injury, and oxidative stress. Trends toward higher levels of S100b, NSE, and UCHL-1 were observed but were not statistically significant. The elevated biomarker levels suggest cumulative brain damage, raising concerns about potential long-term neurological impairments.

CONCLUSIONS

Military aviators are at increased risk for neurobiological injury, including glial and axonal damage, oxidative stress, and early neurodegeneration. These findings emphasize the importance of proactive monitoring and further research to understand the long-term impacts of high-altitude flight on brain health and to develop strategies for mitigating cognitive decline and neurodegenerative risks in this population.

Nocturnal hypoxia in patients with sleep disorders: exploring its role as a mediator between neurotic personality traits and psychological symptoms

Introduction

Sleep disorders often coexist with personality and psychological issues, alongside nocturnal hypoxia. This study investigates the potential mediating role of nocturnal hypoxia between personality traits and psychological symptoms in individuals with sleep disorders.

Methods

A cohort comprising 171 participants reporting sleep disturbances was recruited from Dalian Seventh People's Hospital. Psychological symptoms were assessed using the Symptom Checklist-90-R (SCL-90-R), while personality traits were evaluated using the Eysenck Personality Questionnaire (EPQ). Nocturnal hypoxia status was determined through overnight polysomnography.

Results

Mediation analysis, conducted using SPSS 23.0, demonstrated that the cumulative time of nocturnal peripheral oxygen saturation (SpO2) < 85% (T85) partially mediated the relationship between neuroticism and various psychological symptoms, including somatization (c=0.207, c'=0.164, a*b=0.043, proportion of mediation 20.8%), interpersonal sensitivity (c=0.360, c'=0.326, a*b=0.034, proportion of mediation 9.6%), depression (c=0.277, c'=0.234, a*b=0.042, proportion of mediation 15.3%), anxiety (c=0.240, c'=0.199, a*b=0.041, proportion of mediation 16.9%), hostility (c=0.241, c'=0.205, a*b=0.036, proportion of mediation 14.9%), phobic anxiety (c=0.271, c'=0.241, a*b=0.030, proportion of mediation 11.1%), and psychoticism (c=0.298, c'=0.266, a*b=0.032, proportion of mediation 10.8%).

Discussion

These findings underscore the potential mediating role of nocturnal hypoxia in the association between neuroticism personality traits and psychological symptoms among individuals with sleep disorders. Our research holds considerable significance in advancing the quest for personalized treatments targeting psychological symptoms in individuals with sleep disorders.

The antioxidant barrier, oxidative/nitrosative stress, and protein glycation in allergy: from basic research to clinical practice

Recent studies indicate that oxidative/nitrosative stress is involved in the pathogenesis of asthma, allergic rhinitis, atopic dermatitis, and urticaria. The article aimed to review the latest literature on disruptions in redox homeostasis and protein glycation in allergy patients. It has been shown that enzymatic and non-enzymatic antioxidant systems are impaired in allergic conditions, which increases cell susceptibility to oxidative damage. Reactive oxygen/nitrogen species exacerbate the severity of asthma symptoms by activating inflammatory mediators that cause airway smooth muscle contraction, promote mucus hypersecretion, increase the permeability of lung capillaries, and damage cell membranes. Redox biomarkers could have considerable diagnostic potential in allergy patients. There is no compelling evidence to indicate that antioxidants reduce allergy symptoms' severity or slow disease progression.

A Hypoxia-Inflammation Cycle and Multiple Sclerosis: Mechanisms and Therapeutic Implications

Purpose of Review

Multiple sclerosis (MS) is a complex neurodegenerative disease characterized by inflammation, demyelination, and neurodegeneration. Significant hypoxia exists in brain of people with MS (pwMS), likely contributing to inflammatory, neurodegenerative, and vascular impairments. In this review, we explore the concept of a negative feedback loop between hypoxia and inflammation, discussing its potential role in disease progression based on evidence of hypoxia, and its implications for therapeutic targets.

Recent Findings

In the experimental autoimmune encephalomyelitis (EAE) model, hypoxia has been detected in gray matter (GM) using histological stains, susceptibility MRI and implanted oxygen sensitive probes. In pwMS, hypoxia has been quantified using near-infrared spectroscopy (NIRS) to measure cortical tissue oxygen saturation (StO2), as well as through blood-based biomarkers such as Glucose Transporter-1 (GLUT-1). We outline the potential for the hypoxia-inflammation cycle to drive tissue damage even in the absence of plaques. Inflammation can drive hypoxia through blood-brain barrier (BBB) disruption and edema, mitochondrial dysfunction, oxidative stress, vessel blockage and vascular abnormalities. The hypoxia can, in turn, drive more inflammation.

Summary

The hypoxia-inflammation cycle could exacerbate neuroinflammation and disease progression. We explore therapeutic approaches that target this cycle, providing information about potential treatments in MS. There are many therapeutic approaches that could block this cycle, including inhibiting hypoxia-inducible factor 1-α (HIF-1α), blocking cell adhesion or using vasodilators or oxygen, which could reduce either inflammation or hypoxia. This review highlights the potential significance of the hypoxia-inflammation pathway in MS and suggests strategies to break the cycle. Such treatments could improve quality of life or reduce rates of progression.

Whole-genome sequencing reveals genetic structure and adaptive genes in Nepalese buffalo breeds

BACKGROUND

Indigenous buffaloes, as the important livestock species contributing to economy of the country, are the lifeline of livelihood in Nepal. They are distributed across diverse geographical regions of the country and have adapted to various feeding, breeding, and management conditions. The larger group of these native buffalo breeds are present in narrow and stiff hilly terrains. Their dispersal indicates a possible environmental adaptation mechanism, which is crucial for the conservation of these breeds.

RESULTS

We utilized whole-genome sequencing (WGS) to investigate the genetic diversity, population structure, and selection signatures of Nepalese indigenous buffaloes. We compared 66 whole-genome sequences with 118 publicly available sequences from six river and five swamp buffalo breeds. Genomic diversity parameters indicated genetic variability level in the Nepalese buffaloes comparable to those of Indian breeds, and population genetic structure revealed distinct geography-mediated genetic differentiation among these breeds. We used locus-specific branch length analysis (LSBL) for genome-wide scan, which revealed a list of potentially selected genes in Lime and Parkote breeds that inhabit the hilly region. A gene ontology (GO) analysis discovered that many GO terms were associated with cardiac function regulation. Furthermore, complementary analyses of local selection signatures, tissue expression profiles, and haplotype differences identified candidate genes, including KCNE1, CSF1R, and PDGFRB, related to the regulation of cardiac and pulmonary functions.

CONCLUSIONS

This study is a comprehensive WGS-based genetic analysis of the native Nepalese buffalo breeds. Our study suggested that the Nepalese "hilly" buffaloes, especially the Lime and Parkote breeds, have undergone some characteristic genetic changes and evolved increased cardiac and pulmonary function for their adaptation to the steep hilly terrains of the country.

Hypoxia adaptation mechanism in rats' peripheral auditory system in high altitude migration: a time series transcriptome analysis

High altitude is characterized by low oxygen, low pressure, and high radiation. When migrates from low to high altitudes, the body's tissues and organs experience hypoxic stress and will present acoustic adaptation as the protective response. However, the mechanisms of acoustic adaptation at high altitudes remain unclear. In this study, cochlear tissues from Wistar rats were collected at 15, 30, 60, 120, and 180 days after high-altitude migration. Transcriptome sequencing was conducted and DESeq algorithm revealed expression patterns of Differentially Expressed Genes(DEGs) after high altitude migration. Day 60 is a critical stage for cochlear tissue "damage" and "repair" in high-altitude conditions. Transmission Electron Microscopy (TEM) observations of structures also support the findings. A time-series gene co-expression network algorithm was used to investigate gene regulatory patterns and key genes after migration. Immunofluorescence, immunohistochemistry, and qPCR were per-formed for key gene validation and localization. At Day 60, the peak DEG count occurs in rats migrating to high altitude, aligning with the critical phase for cochlear tissue damage and repair at high altitudes. Repair hinges on synaptic plasticity and myelination-linked processes, influencing modules M4 to M6. Module M4's activation gradually diminishes from its peak. However, the 'damage' effect is orchestrated by inflammation-related processes in modules M3 to M5, with module M3's activation also waning. Key gene module M4, pivotal for repair during this pivotal phase, encompasses Sptbn5, Cldn1, Gfra2, and Lims2 as its core genes. Immunohistochemistry reveals Sptbn5's presence in cochlear neurons, hair cells, Schwann cells and stria vascularis tissue. Cldn1 and Gfra2 predominantly localize within the cochlear neuron region. These results may suggest new directions for future research on acoustic acclimatization to high altitude.

Changes in immune cell populations during acclimatization to high altitude

The immune response to acute hypoxemia may play a critical role in high-altitude acclimatization and adaptation. However, if not properly controlled, hypoxemia-induced inflammation may exacerbate high-altitude pathologies, such as acute mountain sickness (AMS), or other hypoxia-related clinical conditions. Several studies report changes in immune cell subsets at high altitude. However, the mechanisms underlying these changes, and if these alterations are beneficial or maladaptive, remains unknown. To address this, we performed multiparameter flow cytometry on peripheral blood mononuclear cells (PBMCs) collected throughout 3 days of high-altitude acclimatization in healthy sea-level residents (n = 20). Additionally, we conducted in vitro stimulation assays to test if high-altitude hypoxia exposure influences responses of immune cells to subsequent inflammatory stimuli. We found several immune populations were altered at high altitude, including monocytes, T cells, and B cells. Some changes in immune cell populations are potentially correlated with AMS incidence and severity. In vitro high-altitude PBMC cultures stimulated with lipopolysaccharide (LPS) showed no changes in pro-inflammatory cytokine production after 1 day at high-altitude. However, by day three pro-inflammatory cytokine production in response to LPS decreased significantly. These results indicate that high-altitude exposure may initiate an inflammatory response that encompasses innate immune sensitization, with adaptive immune suppression following acclimatization.

A narrative review of periodic breathing during sleep at high altitude: From acclimatizing lowlanders to adapted highlanders

Periodic breathing during sleep at high altitude is almost universal among sojourners. Here, in the context of acclimatization and adaptation, we provide a contemporary review on periodic breathing at high altitude, and explore whether this is an adaptive or maladaptive process. The mechanism(s), prevalence and role of periodic breathing in acclimatized lowlanders at high altitude are contrasted with the available data from adapted indigenous populations (e.g. Andean and Tibetan highlanders). It is concluded that (1) periodic breathing persists with acclimatization in lowlanders and the severity is proportional to sleeping altitude; (2) periodic breathing does not seem to coalesce with poor sleep quality such that, with acclimatization, there appears to be a lengthening of cycle length and minimal impact on the average sleeping oxygen saturation; and (3) high altitude adapted highlanders appear to demonstrate a blunting of periodic breathing, compared to lowlanders, comprising a feature that withstands the negative influences of chronic mountain sickness. These observations indicate that periodic breathing persists with high altitude acclimatization with no obvious negative consequences; however, periodic breathing is attenuated with high altitude adaptation and therefore potentially reflects an adaptive trait to this environment.

Screening of functional genes for hypoxia adaptation in Tibetan pigs by combined genome resequencing and transcriptome analysis

The high-altitude, low-oxygen environment of the Qinghai-Tibet Plateau poses significant challenges for the introduction of superior livestock breeds. However, local plateau species have adapted to thrive and reproduce under these harsh conditions. Understanding the molecular mechanisms behind plateau animals' adaptation to low-oxygen environments is essential for breeding livestock suited to high-altitude regions. Tibetan pigs, which have undergone long-term natural selection and artificial breeding, have developed the ability to survive and reproduce in hypoxic environments. In this study, we conducted whole-genome resequencing of 30 Tibetan pigs from high-altitude regions and 30 Diannan small-ear pigs from low-altitude areas, to identify candidate genes that support Tibetan pigs' adaptation to hypoxic conditions through selection signal analysis. Additionally, we performed transcriptome sequencing on five tissues (heart, liver, spleen, lung, and bone marrow) from both Tibetan pigs and Diannan small-ear pigs to identify genes with significant differential expression between the two breeds. We then integrated the genomic and transcriptomic data by examining the expression of candidate genes identified in selection signal analysis across different tissues. The selection signal analysis identified 10 genes-HES4, ANGPT1, HIF3A, SPHK2, PCK2, RCN3, HIGD2A, DNM2, IRF9, and SRF-that were under positive selection in the Tibetan pig population and are associated with hypoxia adaptation. When combined with transcriptome data, we found that five of these genes-HIF3A, RCN3, HIGD2A, PCK2, and IRF9-exhibited differential expression. Through an integrated approach of selection signal and transcriptome analysis, we identified five key functional genes that contribute to the adaptation of Tibetan pigs to hypoxic environments. These findings offer new insights into the adaptability of plateau animals.

Exploring the Blood Biomarkers and Potential Therapeutic Agents for Human Acute Mountain Sickness Based on Transcriptomic Analysis, Inflammatory Infiltrates and Molecular Docking

A high-altitude, low-pressure hypoxic environment has severe effects on the health and work efficiency of its residents, and inadequate preventive measures and adaptive training may lead to the occurrence of AMS. Acute exposure to hypoxia conditions can have a less-favorable physiological effect on the human immune system. However, the regulation of the immune system in high-altitude environments is extremely complex and remains elusive. This study integrated system bioinformatics methods to screen for changes in immune cell subtypes and their associated targets. It also sought potential therapeutically effective natural compound candidates. The present study observed that monocytes, M1 macrophages and NK cells play a crucial role in the inflammatory response in AMS. IL15RA, CD5, TNFSF13B, IL21R, JAK2 and CXCR3 were identified as hub genes, and JAK2 was positively correlated with monocytes; TNFSF13B was positively correlated with NK cells. The natural compound monomers of jasminoidin and isoliquiritigenin exhibited good binding affinity with JAK2, while dicumarol and artemotil exhibited good binding affinity with TNFSF13B, and all are expected to become a potential therapeutic agents.

Evidence of Intraspecific Adaptive Variation in the American Pika (Ochotona princeps) on a Continental Scale Using a Target Enrichment and Mitochondrial Genome Skimming Approach

Montane landscapes present an array of abiotic challenges that drive adaptive evolution amongst organisms. These adaptations can promote habitat specialisation, which may heighten the risk of extirpation from environmental change. For example, higher metabolic rates in an endothermic species may contribute to heightened cold tolerance, whilst simultaneously limiting heat tolerance. Here, using the climate-sensitive American pika (Ochotona princeps), we test for evidence of intraspecific adaptive variation amongst environmental gradients across the Intermountain West of North America. We leveraged results from previous studies on pika adaptation to generate a custom nuclear target enrichment design to sequence several hundred candidate genes related to cold, hypoxia and dietary detoxification. We also applied a 'genome skimming' approach to sequence mitochondrial DNA. Using genotype-environment association tests, we identified rare genomic variants associated with elevation and temperature variation amongst populations. Amongst mitochondrial genes, we identified intraspecific variation in selective signals and significant changes to the amino acid property equilibrium constant, which may relate to electron transport chain efficiency. These results illustrate a complex dynamic of adaptive variation amongst O. princeps where lineages and populations have adapted to unique regional conditions. Some of the clearest signals of selection were in a genetic lineage that includes pikas of the Great Basin region, which is also where recent localised extirpations have taken place and highlights the risk of losing adaptive alleles during environmental change.

JAK2 Mutation Assessment in Thrombotic Events at Unusual Anatomical Sites: Insights from a High-Altitude Cohort

Introduction

Thrombosis stands as a significant contributor to both morbidity and mortality in individuals afflicted with myeloproliferative neoplasms. This retrospective study investigated the association between JAK2 mutations and venous thrombosis at unusual sites, and in young individuals with ischemic stroke, residing at high altitudes in the Aseer region, Saudi Arabia.

Patients and Methods

Data were collected from two high-altitude referral hospitals over three years (2020-2022). Records of all JAK2 mutation tests were reviewed. Those requested as part of evaluation of thrombosis events, without known myeloproliferative neoplasms (MPNs) were analysed.

Results

Among the 208 JAK2 tests, 40 (19.2%) were linked to thrombotic event evaluations. The cohort, with a median age of 41, included 17 (42.7%) males and 23 females, with 57.5% having completely normal complete blood counts (CBC). Thrombotic events were divided between splanchnic vein thrombosis (36.6%) and cerebral thrombosis (34.1%), while the remaining cases involved unprovoked deep vein thromboses/pulmonary embolisms and portal vein thrombosis. Only 2 (5%) participants tested positive for JAK2 mutations: a 17-year-old male diagnosed concurrently with polycythemia vera after renal vein thrombosis and a 31-year-old woman with hepatic vein thrombosis and a normal CBC.

Conclusion

This study reveals that JAK2 mutations are infrequently found in high-altitude patients with unprovoked DVT, PE, or atypical thrombosis. While JAK2 testing is notably relevant for splanchnic vein thrombosis, its routine use for other thrombotic events, particularly with normal CBC results, remains uncertain. Given the study's limitations, further prospective research with larger cohorts is needed to refine guidelines for JAK2 mutation testing in various thrombotic contexts.

Dietary patterns related to attention and physiological function in high-altitude migrants

High altitude exposure negatively affects human attentional function. However, no studies have explored the regulation of attentional and physiological functions from a dietary perspective. A total of 116 Han Chinese students from Tibet University who were born and raised in a plain area and had been living in Tibet for > 2 years were recruited. All participants were male migrants. A food frequency questionnaire, complete blood count, and attention network test were performed on the participants. Pearson's correlation was applied to assess the reliability and validity of the food frequency questionnaire. Principal component analysis was utilized to extract dietary patterns. A linear mixed model was employed to account for individual differences. The results showed that the five main dietary patterns were coarse grain, alcohol, meat, protein, and snacking dietary patterns. Furthermore, individuals who adhered to the coarse grain dietary pattern and had high mean corpuscular hemoglobin showed better attentional performance. Individuals with high alcohol consumption and systemic immune-inflammation index levels exhibited worse attentional performance. These findings imply that high-altitude migrants should include more coarse grains in their daily diet and avoid excessive alcohol consumption to improve attention.

Acute hypoxic conditions preceding endotoxin administration result in an increased proinflammatory cytokine response in healthy men

Tissues often experience hypoxia at sites of inflammation due to malperfusion, massive immune cell recruitment, and increased oxygen consumption. Organisms adapt to these hypoxic conditions through the transcriptional activation of various genes. In fact, there is significant crosstalk between the transcriptional responses to hypoxia and inflammatory processes. This interaction, named inflammatory hypoxia, plays a crucial role in various diseases including malignancies, chronic inflammatory lung diseases, and sepsis. To further elucidate the crosstalk between hypoxia and inflammation in vivo and assess its potential for innovative therapies, our study aimed at investigating the impact of acute hypoxic conditions on inflammation-induced immune responses. To this end, we exposed healthy human subjects to hypoxia either before (hypoxia priming) or after a single intravenous (i.v.) injection of 0.4 ng/kg LPS. Our data show that hypoxia exposure prior to LPS injection (hypoxia priming) amplified the proinflammatory response. This was reflected by an increase in body temperature, plasma noradrenaline levels, and the production of proinflammatory cytokines (i.e., IL-6 and TNF-α), compared with LPS control conditions. These effects were not observed when participants were exposed to hypoxia after LPS administration, demonstrating that the interaction between hypoxia and inflammation highly depends on the timing of both stimuli. Our findings suggest that acute hypoxia (i.e., hypoxia priming) modulates transient inflammation, leading to an enhanced proinflammatory response in healthy human subjects. This highlights the need for further investigations to understand the pathology of various hypoxia-inducible factor (HIF)-associated inflammatory diseases and to develop suitable, innovative therapies.NEW & NOTEWORTHY To our knowledge, this is the first in vivo study investigating the effects of hypoxia preceding (hypoxia priming) or following LPS administration on the endotoxin-induced inflammatory response in healthy human subjects. The data show that hypoxia priming amplified the proinflammatory response, reflected by an increased body temperature, increased plasma noradrenaline levels, and higher production of proinflammatory cytokines (i.e., IL-6 and TNF-α) compared with LPS control conditions.

Effects of 12 Weeks of Combined Exercise Training in Normobaric Hypoxia on Arterial Stiffness, Inflammatory Biomarkers, and Red Blood Cell Hemorheological Function in Obese Older Women

BACKGROUND/OBJECTIVES

The present study examined the effect of 12-week combined exercise training in normobaric hypoxia on arterial stiffness, inflammatory biomarkers, and red blood cell (RBC) hemorheological function in 24 obese older women (mean age: 67.96 ± 0.96 years).

METHODS

Subjects were randomly divided into two groups (normoxia (NMX; n = 12) and hypoxia (HPX; n = 12)). Both groups performed aerobic and resistance exercise training programs three times per week for 12 weeks, and the HPX group performed exercise programs in hypoxic environment chambers during the intervention period. Body composition was estimated using bioelectrical impedance analysis equipment. Arterial stiffness was measured using an automatic waveform analyzer. Biomarkers of inflammation and oxygen transport (tumor necrosis factor alpha, interleukin 6 (IL-6), erythropoietin (EPO), and vascular endothelial growth factor (VEGF)), and RBC hemorheological parameters (RBC deformability and aggregation) were analyzed.

RESULTS

All variables showed significantly more beneficial changes in the HPX group than in the NMX group during the intervention. The combined exercise training in normobaric hypoxia significantly reduced blood pressure (systolic blood pressure: p < 0.001, diastolic blood pressure: p < 0.001, mean arterial pressure: p < 0.001, pulse pressure: p < 0.05) and brachial-ankle pulse wave velocity (p < 0.001). IL-6 was significantly lower in the HPX group than in the NMX group post-test (p < 0.001). Also, EPO (p < 0.01) and VEGF (p < 0.01) were significantly higher in the HPX group than in the NMX group post-test. Both groups showed significantly improved RBC deformability (RBC EI_3Pa) (p < 0.001) and aggregation (RBC AI_3Pa) (p < 0.001).

CONCLUSIONS

The present study suggests that combined exercise training in normobaric hypoxia can improve inflammatory biomarkers and RBC hemorheological parameters in obese older women and may help prevent cardiovascular diseases.

The role of oxidative stress and neuroinflammatory mediators in the pathogenesis of high-altitude cerebral edema in rats

High-altitude environments present extreme conditions characterized by low barometric pressure and oxygen deficiency, which can disrupt brain functioning and cause edema formation. The objective of the present study is to investigate several biomolecule expressions and their role in the development of High Altitude Cerebral Edema in a rat model. Specifically, the study focuses on analyzing the changes in total arginase, nitric oxide, and lipid peroxidation (MDA) levels in the brain following acute hypobaric hypoxic exposure (7620 m, SO2=8.1 %, for 24 h) along with the histopathological assessment. The histological examination revealed increased TNF-α activity, and an elevated number of mast cells in the brain, mainly in the hippocampus and cerebral cortex. The research findings demonstrated that acute hypobaric hypoxic causes increased levels of apoptotic cells, shrinkage, and swelling of neurons, accompanied by the formation of protein aggregation in the brain parenchyma. Additionally, the level of nitric oxide and MDA was found to have increased (p<0.0001), however, the level of arginase decreased indicating active lipid peroxidation and redox imbalance in the brain. This study provides insights into the pathogenesis of HACE by evaluating some biomolecules that play a pivotal role in the inflammatory response and the redox landscape in the brain. The findings could have significant implications for understanding the neuronal dysfunction and the pathological mechanisms underlying HACE development.

p53 lysine-lactylated modification contributes to lipopolysaccharide-induced proinflammatory activation in BV2 cell under hypoxic conditions

p53 has diversity functions in regulation of transcription, cell proliferation, cancer metastasis, etc. Recent studies have shown that p53 and nuclear factor-κB (NF-κB) co-regulate proinflammatory responses in macrophages. However, the role of p53 lysine lactylation (p53Kla) in mediating proinflammatory phenotypes in microglia under hypoxic conditions remains unclear. In the current study, we investigated the proinflammatory activation exacerbated by hypoxia and the levels of p53Kla in microglial cells. BV2 cells, an immortalized mouse microglia cell line, were divided into control, lipopolysaccharide (LPS)-induced, hypoxia (Hy), and LPS-Hy groups. The protein expression levels of p53 and p53Kla and the activation of microglia were compared among the four groups. Sodium oxamate and mutant p53 plasmids were transfected into BV2 cells to detect the effect of p53Kla on microglial proinflammatory activation. LPS-Hy stimulation significantly upregulated p53Kla levels in both the nucleus and the cytoplasm of BV2 cells. In contrast, the p53 protein levels were downregulated. LPS-Hy stimulation upregulated phosphorylated p65 protein levels in nuclear and activated the NF-κB pathway in BV2 cells, resulting in increased expression of pro-inflammatory cytokines (iNOS, IL6, IL1β, TNFα), enhanced cell viability, and concomitantly, increased cytotoxicity. In conclusion, p53 lysine-lactylated modification contributes to LPS-induced proinflammatory activation in BV2 cells under hypoxia through NF-κB pathway and inhibition of lactate production may alleviate neuroinflammatory injury.

Exposure to normobaric hypoxia shapes the acute inflammatory response in human whole blood cells in vivo

Cells of the immune defence, especially leukocytes, often have to perform their function in tissue areas that are characterized by oxygen deficiency, so-called hypoxia. Physiological hypoxia significantly affects leukocyte function and controls the innate and adaptive immune response mainly through transcriptional gene regulation via the hypoxia-inducible factors (HIFs). Multiple pathogens including components of bacteria, such as lipopolysaccharides (LPS) trigger the activation of leukocytes. HIF pathway activation enables immune cells to adapt to both hypoxic environments in physiological and inflammatory settings and modulates immune cell responses through metabolism changes and crosstalk with other immune-relevant signalling pathways. To study the mutual influence of both processes in vivo, we used a human endotoxemia model, challenging participants with an intravenous LPS injection post or prior to a 4-h stay in a hypoxic chamber with normobaric hypoxia of 10.5% oxygen. We analysed changes in gene expression in whole blood cells and determined inflammatory markers to unveil the crosstalk between both processes. Our investigations showed differentially altered gene expression patterns of HIF and target genes upon in vivo treatment with LPS and hypoxia. Further, we found evidence for effects of hypoxic priming upon inflammation in combination with immunomodulatory effects in whole blood cells in vivo. Our work elucidates the complex interplay of hypoxic and inflammatory HIF regulation in human immune cells and offers new perspectives for further clinical research.

Network pharmacology and in vivo experimental studies reveal the protective effects of 6-hydroxygenistein against hypobaric hypoxia-induced brain injury

Hypobaric hypoxia-induced brain injury (HHBI) is a progressive neurodegenerative disease that has still not been effectively treated. There are several different mechanisms involved in HHBI. Among them, oxidative stress and inflammation response predominate. 6-hydroxygenistein (4',5,6,7-tetrahydroxyisoflavone, 6-OHG) is a hydroxylated derivative of genistein with excellent antioxidant activity, however, the protective effects and underlying mechanisms against HHBI have not been clarified. In the present study, we aimed to explore the mechanisms of action of 6-OHG on HHBI using network pharmacology and experimental validation. Network pharmacology analysis revealed 186 candidate targets through the intersection of the targets of 6-OHG and related genes in HHBI, which were mainly enriched in oxidative stress and inflammation response. Moreover, key targets of 6-OHG against HHBI, namely Nrf2 and NF-κB, were screened and found to be closely related to oxidative stress and inflammation response. Subsequent in vivo experiments revealed that 6-OHG treatment attenuated oxidative stress and inflammation response, prevented energy disorder and apoptosis as well as maintained the BBB integrity in HHBI mice. In addition, 6-OHG administration up-regulated the expressions of Nrf2 and HO-1 and down-regulated the expressions of NF-κB and NLRP3, thereby inhibiting oxidative stress and inflammation response. Hence, the present study demonstrates that 6-OHG protects against HHBI by stimulating the Nrf2/HO-1 signaling pathway and suppressing the NF-κB/NLRP3 signaling pathway.

The cytoprotective effect of Gymnema inodorum leaf extract against hypoxia-induced cardiomyocytes injury

Ischemic heart disease stands out as a major global contributor to mortality, with the initiation of hypoxia, marked by reduced oxygen availability, disrupting the balance of reactive oxygen species (ROS), leading to cellular injury. Exploring antioxidants derived from medicinal plants is becoming more interesting as a potential alternative treatment, especially for mitigating myocardial injury. Thus, this study aimed to assess the cytoprotective efficacy of Gymnema inodorum leaf extract (GIE) in a rat cardiac myoblast, H9c2, subjected to an in vitro hypoxia. The cell viability, intracellular ROS production and the expression of inflammatory cytokines were quantified, and hypoxia-induced cell morphology changes were observed using confocal fluorescence microscopy. The results showed that GIE notably enhanced cell viability, preserving membrane integrity, when compared with the hypoxic group. Remarkably, GIE significantly reduced hypoxia-induced intracellular ROS production, attributable to its inherent antioxidant properties. Furthermore, GIE significantly reduced interleukin (IL)-1β, interleukin (IL)-6 mRNA expression level and tended to reduce tumor necrosis factor-α (TNF-α) mRNA expression. In conclusion, these findings underscore the potential of GIE in mitigating hypoxia-induced myocardial injury, highlighting its robust antioxidant and anti-inflammatory attributes.

Fetal chronic hypoxia does not affect urinary presepsin levels in newborns at birth

OBJECTIVES

Early sepsis detection and diagnosis still constitutes an open issue since the accuracy of standard-of care parameters is biased by a series of perinatal factors including hypoxia. Therefore, we aimed at investigating the effect of fetal chronic hypoxia insult on urine levels of a promising new marker of sepsis, namely presepsin (P-SEP).

METHODS

We conducted a prospective case-control study in 22 cases of early-intrauterine growth restriction (E-IUGR) compared with 22 small-for-gestational-age (SGA) newborns and 66 healthy controls. P-SEP urine samples were collected over the first 72 h from birth. Blood culture and C-reactive protein (CRP) blood levels were measured in E-IUGR and SGA infants. Perinatal standard monitoring parameters and main outcomes were also recorded.

RESULTS

No significant urinary P-SEP differences (p>0.05, for all) were observed among studied groups. Moreover, no significant correlations (p>0.05, for both) between urinary P-SEP and blood CRP levels in both E-IUGR and SGA groups (R=0.08; R=0.07, respectively) were observed.

CONCLUSIONS

The present results showing the lack of influence of fetal chronic hypoxia on urinary P-SEP levels offer additional data to hypothesize the possible use of urinary P-SEP measurement in neonates in daily clinical practice. Further multicenter prospective data are needed, including infants with early-onset sepsis.

Analysis of Ferritin, Hepcidin, Zinc, C-Reactive Protein and IL-6 Levels in COVID-19 in Patients Living at Different Altitudes in Peru

BACKGROUND

Despite great scientific efforts, understanding the role of COVID-19 clinical biomarkers remains a challenge.

METHODS

A cross-sectional descriptive study in two Peruvian cities at different altitudes for comparison: Lima and Huaraz. In each place, three groups were formed, made up of 25 patients with COVID-19 in the ICU, 25 hospitalized patients with COVID-19 who did not require the ICU, and 25 healthy subjects as a control group. Five biomarkers were measured: IL-6, hepcidin, ferritin, C-reactive protein, and zinc using ELISA assays.

RESULTS

Ferritin, C-reactive protein, and IL-6 levels were significantly higher in the ICU and non-ICU groups at both study sites. In the case of hepcidin, the levels were significantly higher in the ICU group at both study sites compared to the non-ICU group. Among the groups within each study site, the highest altitude area presented statistically significant differences between its groups in all the markers evaluated. In the lower altitude area, differences were only observed between the groups for the zinc biomarker.

CONCLUSION

COVID-19 patients residing at high altitudes tend to have higher levels of zinc and IL-6 in all groups studied compared to their lower altitude counterparts.

Histone deacetylase Sir2 promotes the systemic Candida albicans infection by facilitating its immune escape via remodeling the cell wall and maintaining the metabolic activity

Histone deacetylation affects Candida albicans (C. albicans) pathogenicity by modulating virulence factor expression and DNA damage. The histone deacetylase Sir2 is associated with C. albicans plasticity and maintains genome stability to help C. albicans adapt to various environmental niches. However, whether Sir2-mediated chromatin modification affects C. albicans virulence is unclear. The purpose of our study was to investigate the effect of Sir2 on C. albicans pathogenicity and regulation. Here, we report that Sir2 is required for C. albicans pathogenicity, as its deletion affects the survival rate, fungal burden in different organs and the extent of tissue damage in a mouse model of disseminated candidiasis. We evaluated the impact of Sir2 on C. albicans virulence factors and revealed that the Sir2 null mutant had an impaired ability to adhere to host cells and was more easily recognized by the innate immune system. Comprehensive analysis revealed that the disruption of C. albicans adhesion was due to a decrease in cell surface hydrophobicity rather than the differential expression of adhesion genes on the cell wall. In addition, Sir2 affects the distribution and exposure of mannan and β-glucan on the cell wall, indicating that Sir2 plays a role in preventing the immune system from recognizing C. albicans. Interestingly, our results also indicated that Sir2 helps C. albicans maintain metabolic activity under hypoxic conditions, suggesting that Sir2 contributes to C. albicans colonization at hypoxic sites. In conclusion, our findings provide detailed insights into antifungal targets and a useful foundation for the development of antifungal drugs.

IMPORTANCE

Candida albicans (C. albicans) is the most common opportunistic fungal pathogen and can cause various superficial infections and even life-threatening systemic infections. To successfully propagate infection, this organism relies on the ability to express virulence-associated factors and escape host immunity. In this study, we demonstrated that the histone deacetylase Sir2 helps C. albicans adhere to host cells and escape host immunity by mediating cell wall remodeling; as a result, C. albicans successfully colonized and invaded the host in vivo. In addition, we found that Sir2 contributes to carbon utilization under hypoxic conditions, suggesting that Sir2 is important for C. albicans survival and the establishment of infection in hypoxic environments. In summary, we investigated the role of Sir2 in regulating C. albicans pathogenicity in detail; these findings provide a potential target for the development of antifungal drugs.

16α-OHE1 alleviates hypoxia-induced inflammation and myocardial damage via the activation of β2-Adrenergic receptor

OBJECTIVE

Myocardial injuries resulting from hypoxia are a significant concern, and this study aimed to explore potential protective strategies against such damage. Specifically, we sought to investigate the cardioprotective effects of 16α-hydroxyestrone (16α-OHE1).

METHODS

Male Sprague‒Dawley (SD) rats were subjected to hypoxic conditions simulating high-altitude exposure at 6000 m in a low-pressure chamber for 7 days. Before and during hypoxic exposure, estradiol (E2) and various doses of 16α-OHE1 were administered for 14 days. Heart weight/body weight (HW/BW), myocardial structure, Myocardial injury indicators and inflammatory infiltration in rats were measured. H9C2 cells cultured under 5% O2 conditions received E2 and varying doses of 16α-OHE1; Cell viability, apoptosis, inflammatory infiltration, and Myocardial injury indicators were determined. Expression levels of β2AR were determined in rat hearts and H9C2 cells. The β2AR inhibitor, ICI 118,551, was employed to investigate β2AR's role in 16α-OHE1's cardioprotective effects.

RESULTS

Hypoxia led to substantial myocardial damage, evident in increased heart HW, CK-MB, cTnT, ANP, BNP, structural myocardial changes, inflammatory infiltration, and apoptosis. Pre-treatment with E2 and 16α-OHE1 significantly mitigated these adverse changes. Importantly, the protective effects of E2 and 16α-OHE1 were associated with the upregulation of β2AR expression in both rat hearts and H9C2 cells. However, inhibition of β2AR by ICI 118,551 in H9C2 cells nullified the protective effect of 16α-OHE1 on myocardium.

CONCLUSION

Our findings suggest that 16α-OHE1 can effectively reduce hypoxia-induced myocardial injury in rats through β2ARs, indicating a promising avenue for cardioprotection.

Intermittent Versus Sustained Hypoxemia from Sleep-disordered Breathing: Outcomes in Patients with Chronic Lung Disease and High Altitude

In a variety of physiologic and pathologic states, people may experience both chronic sustained hypoxemia and intermittent hypoxemia ("combined" or "overlap" hypoxemia). In general, hypoxemia in such instances predicts a variety of maladaptive outcomes, including excess cardiovascular disease or mortality. However, hypoxemia may be one of the myriad phenotypic effects in such states, making it difficult to ascertain whether adverse outcomes are primarily driven by hypoxemia, and if so, whether these effects are due to intermittent versus sustained hypoxemia.

Low- and moderate-intensity aerobic exercise improves the physiological acclimatization of lowlanders on the Tibetan plateau

This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high altitudes (HA), considering the physiological challenges of hypoxic conditions. Overall, 121 lowlanders who had lived on the Tibetan Plateau for >2 years and were still living at HA during the measurements were randomly classified into four groups. Each individual of the low-intensity (LI), moderate-intensity (MI), and high-intensity (HI) groups performed 20 sessions of aerobic exercise at HA (3680 m) over 4 weeks, while the control group (CG) did not undergo any intervention. Physiological responses before and after the intervention were observed. The LI and MI groups experienced significant improvement in cardiopulmonary fitness (0.27 and 0.35 L/min increases in peak oxygen uptake [V ˙ $\dot{\mathrm{V}}$ O2peak], both p < 0.05) after exercise intervention, while the hematocrit (HCT) remained unchanged (p > 0.05). However, HI exercise was less efficient for cardiopulmonary fitness of lowlanders (0.02 L/min decrease inV ˙ $\dot{\mathrm{V}}$ O2peak, p > 0.05), whereas both the HCT (1.74 %, p < 0.001) and glomerular filtration rate (18.41 mL/min, p < 0.001) increased with HI intervention. Therefore, LI and MI aerobic exercise, rather than HI, can help lowlanders in Tibet become more acclimated to the HA by increasing cardiopulmonary function and counteracting erythrocytosis.

Live Microscopy of Multicellular Spheroids with the Multimodal Near-Infrared Nanoparticles Reveals Differences in Oxygenation Gradients

Assessment of hypoxia, nutrients, metabolite gradients, and other hallmarks of the tumor microenvironment within 3D multicellular spheroid and organoid models represents a challenging analytical task. Here, we report red/near-infrared (NIR) emitting cell staining with O2-sensitive nanoparticles, which enable measurements of spheroid oxygenation on a conventional fluorescence microscope. Nanosensor probes, termed "MMIR" (multimodal infrared), incorporate an NIR O2-sensitive metalloporphyrin (PtTPTBPF) and deep red aza-BODIPY reference dyes within a biocompatible polymer shell, allowing for oxygen gradient quantification via fluorescence ratio and phosphorescence lifetime readouts. We optimized staining techniques and evaluated the nanosensor probe characteristics and cytotoxicity. Subsequently, we applied nanosensors to the live spheroid models based on HCT116, DPSCs, and SKOV3 cells, at rest, and treated with drugs affecting cell respiration. We found that the growth medium viscosity, spheroid size, and formation method influenced spheroid oxygenation. Some spheroids produced from HCT116 and dental pulp stem cells exhibited "inverted" oxygenation gradients, with higher core oxygen levels than the periphery. This contrasted with the frequently encountered "normal" gradient of hypoxia toward the core caused by diffusion. Further microscopy analysis of spheroids with an "inverted" gradient demonstrated metabolic stratification of cells within spheroids: thus, autofluorescence FLIM of NAD(P)H indicated the formation of a glycolytic core and localization of OxPhos-active cells at the periphery. Collectively, we demonstrate a strong potential of NIR-emitting ratiometric nanosensors for advanced microscopy studies targeting live and quantitative real-time monitoring of cell metabolism and hypoxia in complex 3D tissue models.