Targeting myeloid-derived suppressor cells by inhibiting hypoxia-inducible factor 1α could improve tumor progression.

Myeloid-derived suppressor cells (MDSCs) are a subset of immature myeloid cells that inhibit anti-tumor immunity and contribute to poor cancer outcomes. In this study, the authors used multi-color flow cytometry to detect changes in MDSCs in patients with cancer and tumor-bearing mice. Then the authors studied changes in MDSCs ratio and mouse tumors after administration of hypoxia-inducible factor 1α (HIF-1α) inhibitor. The results showed that the ratio of MDSCs, specifically polymorphonuclear MDSCs (PMN-MDSCs), was higher in patients with cancer, and both PMN-MDSCs and monocytic MDSCs (M-MDSCs) ratio were higher in tumor-bearing mice. When provided with the HIF-1α inhibitor LW-6, the ratio of MDSCs decreased in tumor-bearing mice, particularly PMN-MDSCs, and the volume of liver metastases also decreased. The authors' findings suggest that reducing MDSCs by inhibiting hypoxia-inducible factor 1α may slow tumor progression.

DATA in BRIEF of: Adaptative mechanisms indicated by placental protein expression changes in high-altitude Tibetan women during vaginal delivery.

Over a period of 30,000 to 40,000 years, high-altitude Tibetans have physiologically and genetically adapted to conditions such as hypoxia, low temperature, and high-intensity ultraviolet radiation. Based on the unique physiological and morphological characteristics of the Tibetan people, they have outstanding hypoxia adaptation skills and can continue to thrive in plateau hypoxia. The placenta of high-altitude Tibetans is protected from oxidative stress during delivery; however, little is known about changes in placental protein expression during vaginal delivery. In this study, we aimed to reveal these adaptive mechanisms by studying changes in placental protein expression during vaginal delivery in high-altitude Tibetans, low-altitude Tibetans, and low-altitude Han populations. Studying the changing mechanisms of maternal responses to hypoxia at high altitudes can reveal the molecular mechanisms of maternal and fetal adaptation to hypoxia at high altitudes and provide theories for preventing and treating maternal hypoxia and intrauterine growth and development restriction caused by other diseases.

Role of ubiquitination in the occurrence and development of osteoporosis (Review).

The ubiquitin (Ub)­proteasome system (UPS) plays a pivotal role in maintaining protein homeostasis and function to modulate various cellular processes including skeletal cell differentiation and bone homeostasis. The Ub ligase E3 promotes the transfer of Ub to the target protein, especially transcription factors, to regulate the proliferation, differentiation and survival of bone cells, as well as bone formation. In turn, the deubiquitinating enzyme removes Ub from modified substrate proteins to orchestrate bone remodeling. As a result of abnormal regulation of ubiquitination, bone cell differentiation exhibits disorder and then bone homeostasis is affected, consequently leading to osteoporosis. The present review discussed the role and mechanism of UPS in bone remodeling. However, the specific mechanism of UPS in the process of bone remodeling is still not fully understood and further research is required. The study of the mechanism of action of UPS can provide new ideas and methods for the prevention and treatment of osteoporosis. In addition, the most commonly used osteoporosis drugs that target ubiquitination processes in the clinic are discussed in the current review.

The contribution and mechanism of hypoxia/USP19/Beclin-1 feed-forward loop in cervical cancer.

Cervical cancer ranks fourth in female mortality. Since the mechanisms for pathogenesis of cervical cancer are still poorly understood, the effective treatment options are lacking. Beclin-1 exhibits an inhibitory role in cervical cancer via suppressing the proliferation, invasion, and migration of cervical cancer cells. It is reported that USP19 removes the K11-linked ubiquitination of Beclin-1 to protect Beclin-1 from proteasomal degradation. Interestingly, we found that hypoxia induced a significant decrease of both Beclin-1 and USP19, suggesting that hypoxia could dually inhibit the protein level of Beclin-1 through a type 2 coherent feed-forward loop (C2-FFL, hypoxia ⊸ Beclin-1 integrating with hypoxia ⊸ USP19 → Beclin-1) to promote the occurrence and development of cervical cancer. Furthermore, mathematical modeling revealed that under the hypoxic environment of solid tumor, the hypoxia/USP19/Beclin-1 coherent feed-forward loop could significantly reduce the protein level of Beclin-1, greatly enhance the sensitivity of Beclin-1 to hypoxia, strikingly restrict the heterogeneity of Beclin-1, and contribute to the low positive rate of Beclin-1 in cervical cancer. It is expected to have significance for elucidating the underlying mechanisms of the occurrence and development of cervical cancer and to provide novel targets and strategies for prevention and treatment of cervical cancer.

Tibetan mesenchymal stem cell-derived exosomes alleviate pulmonary vascular remodeling in hypoxic pulmonary hypertension rats.

Hypoxic pulmonary hypertension (HPH) is characterized by progressive pulmonary vasoconstriction, vascular remodeling, and right ventricular hypertrophy, causing right heart failure. This study aimed to investigate the therapeutic effects of exosomes from Tibetan umbilical cord mesenchymal stem cells on HPH via the TGF-ß1/Smad2/3 pathway, comparing them with exosomes from Han Chinese individuals. An HPH rat model was established in vivo, and a hypoxia-induced injury in the rat pulmonary artery smooth muscle cells (rPASMCs) was simulated in vitro. Exosomes from human umbilical cord mesenchymal stem cells were administered to HPH model rats or added to cultured rPASMCs. The therapeutic effects of Tibetan-mesenchymal stem cell-derived exosomes (Tibetan-MSC-exo) and Han-mesenchymal stem cell-derived exosomes (Han-MSC-exo) on HPH were investigated through immunohistochemistry, western blotting, EdU, and Transwell assays. The results showed that Tibetan-MSC-exo significantly attenuated pulmonary vascular remodeling and right ventricular hypertrophy in HPH rats compared with Han-MSC-exo. Tibetan-MSC-exo demonstrated better inhibition of hypoxia-induced rPASMCs proliferation and migration. Transcriptome sequencing revealed upregulated genes (Nbl1, Id2, Smad6, and Ltbp1) related to the TGFß pathway. Nbl1 knockdown enhanced hypoxia-induced rPASMCs proliferation and migration, reversing Tibetan-MSC-exo-induced downregulation of TGFß1 and p-Smad2/3. Furthermore, TGFß1 overexpression hindered the therapeutic effects of Tibetan-MSC-exo and Han-MSC-exo on hypoxic injury. These findings suggest that Tibetan-MSC-exo favors HPH treatment better than Han-MSC-exo, possibly through the modulation of the TGFß1/Smad2/3 pathway via Nbl1.

Newsights of endoplasmic reticulum in hypoxia.

The endoplasmic reticulum (ER) is important to cells because of its essential functions, including synthesizing three major nutrients and ion transport. When cellular homeostasis is disrupted, ER quality control (ERQC) system is activated effectively to remove misfolded and unfolded proteins through ER-phagy, ER-related degradation (ERAD), and molecular chaperones. When unfolded protein response (UPR) and ER stress are activated, the cell may be suffering a huge blow, and the most probable consequence is apoptosis. The membrane contact points between the ER and sub-organelles contribute to communication between the organelles. The decrease in oxygen concentration affects the morphology and structure of the ER, thereby affecting its function and further disrupting the stable state of cells, leading to the occurrence of disease. In this study, we describe the functions of ER-, ERQC-, and ER-related membrane contact points and their changes under hypoxia, which will help us further understand ER and treat ER-related diseases.

Ubenimex combined with Albendazole for the treatment of Echinococcus multilocularis-induced alveolar echinococcosis in mice.

Introduction: Alveolar echinococcosis (AE) is a parasitic disease caused by E. multilocularis metacestodes and it is highly prevalent in the northern hemisphere. We have previously found that vaccination with E. multilocularis-Leucine aminopeptidase (EM-LAP) could inhibit the growth and invasion of E. multilocularis in host liver, and Ubenimex, a broad-spectrum inhibitor of LAP, could also inhibit E. multilocularis invasion but had a limited effect on the growth and development of E. multilocularis. Methods: In this study, the therapeutic effect of Ubenimex combined with Albendazole on AE was evaluated. Mice were intraperitoneally injected with protoscoleces and imaging examination was performed at week 8 and week 16 to detect cyst change. During this period, mice were intraperitoneally injected with Ubenimex and intragastrically administered with Albendazole suspension. At last, the therapeutic effect was evaluated by morphological and pathological examination and liver function. Results: The results revealed that the combined treatment could inhibit the growth and infiltration of cysts in BALB/c mice infected with E. multilocularis protoscoleces. The weight, number, invasion and fibrosis of cysts were reduced in mice treated with Ubenimex in combination with Albendazole. The same effect was achieved by the single Ubenimex treatment because of its inhibitory effect on LAP activity, but it was less effective in inhibiting the growth of cysts. The levels of ALT, AST, TBIL, DBIL, ALP, and γ-GT were reduced after the combined treatment, indicating that treatment with both Ubenimex and Albendazole could alleviate liver damage. Discussion: This study suggests that the combined treatment with Ubenimex and Albendazole could be a potential therapeutic strategy for E. multilocularis infections.

[Effects of human umbilical cord mesenchymal stem cells (MSCs)-derived exosomes on pulmonary vascular remodeling in hypoxic pulmonary hypertension].

The present study aimed to investigate the effect of human umbilical cord mesenchymal stem cells (MSCs)-derived exosomes (MSCs-Exo) on mice with hypoxic pulmonary hypertension (HPH). MSCs were isolated and cultured from human umbilical cords under aseptic conditions, and exosomes were extracted from the supernatants and identified. Healthy SPF C57BL/6 mice were randomly divided into three groups: normoxic group, hypoxic group, and hypoxic+MSCs-Exo group. Mice in the hypoxic group and the hypoxic+MSCs-Exo group were maintained for 28 d at an equivalent altitude of 5 000 m in a hypobaric chamber to establish HPH mouse model. The mice in the hypoxic+MSCs-Exo group were injected with MSCs-Exo via tail vein before hypoxia and on days 1, 3, 5 and 9 of hypoxia, and the mice in the other two groups were injected with PBS. At the end of the experiment, echocardiography was performed to detect pulmonary arterial acceleration time/pulmonary arterial ejection time ratio (PAAT/PET), right ventricular free wall thickness, and right ventricular hypertrophy index RV/(LV+S). HE staining was performed to observe the lung tissue morphology. EVG staining was performed to observe elastic fiber hyperplasia. Immunohistochemistry was performed to detect α smooth muscle actin (α-SMA) expression in lung tissue. Immunofluorescence staining was used to detect macrophage infiltration in lung tissue. qPCR was performed to detect IL-1ß and IL-33 in lung tissue, and cytometric bead array was performed to detect IL-10 secretion. Western blotting was used to detect the M1 macrophage marker iNOS, M2 macrophage marker Arg-1 and IL-33/ST2 pathway proteins in lung tissues. The results showed that hypoxia increased pulmonary artery pressure and pulmonary vascular remodeling, increased macrophage infiltration, IL-1ß and IL-33 expression (P < 0.05) and upregulated the IL-33/ST2 pathway (P < 0.05). Compared with the hypoxic group, MSCs-Exo treatment increased PAAT/PET (P < 0.05), decreased right ventricular free wall thickness (P < 0.05), right ventricular hypertrophy index RV/(LV+S) (P < 0.05), α-SMA expression in small pulmonary vessels (P < 0.05), and inflammatory factors including IL-1ß and IL-33 expression in lung tissue, however increased IL-10 secretion (P < 0.05). In addition, MSCs-Exo treatment upregulated Arg-1 and downregulated iNOS and IL-33/ST2 (P < 0.05). The results suggest that MSC-Exo may alleviate HPH through their immunomodulatory effects.

Hypoxia-inducible factor-2α promotes fibrosis in non-alcoholic fatty liver disease by enhancing glutamine catabolism and inhibiting yes-associated protein phosphorylation in hepatic stellate cells.

Non-alcoholic fatty liver disease (NAFLD) has a high global prevalence and affects approximately one-third of adults, owing to high-fat dietary habits and a sedentary lifestyle. The role of hypoxia-inducible factor 2α (HIF-2α) in NAFLD progression remains unknown. This study aimed to investigate the effects of chronic hypoxia on NAFLD progression by examining the role of hypoxia-inducible factor 2α (HIF-2α) activation and that of hepatic stellate cell (HSC)-derived myofibroblasts through glutaminolysis. We hypothesised that hypoxia exacerbates NAFLD by promoting HIF-2α upregulation and inhibiting phosphorylated yes-associated protein (YAP), and that increasing YAP expression enhances HSC-derived myofibroblasts. We studied patients with NAFLD living at high altitudes, as well as animal models and cultured cells. The results revealed significant increases in HSC-derived myofibroblasts and collagen accumulation caused by HIF-2α and YAP upregulation, both in patients and in a mouse model for hypoxia and NAFLD. HIF-2α and HIF-2α-dependent YAP downregulation reduced HSC activation and myofibroblast levels in persistent chronic hypoxia. Furthermore, hypoxia-induced HIF-2α upregulation promoted YAP and inhibited YAP phosphorylation, leading to glutaminase 1 (GLS1), SLC38A1, α-SMA, and Collagen-1 overexpression. Additionally, hypoxia restored mitochondrial adenosine triphosphate production and reactive oxygen species (ROS) overproduction. Thus, chronic hypoxia-induced HIF-2α activation enhances fibrosis and NAFLD progression by restoring mitochondrial ROS production and glutaminase-1-induced glutaminolysis, which is mediated through the inhibition of YAP phosphorylation and increased YAP nuclear translocation. In summary, HIF-2α plays a pivotal role in NAFLD progression during chronic hypoxia.

A Bioengineered Nanovesicle Vaccine Boosts T-B cell Interaction for Immunotherapy of Echinococcus multilocularis.

Alveolar echinococcosis (AE) is a zoonotic parasitic disease, resulting from being infected with the metacestode larvae of the tapeworm Echinococcus multilocularis (E. multilocularis). Novel prophylactic and therapeutic interventions are urgently needed since the current chemotherapy displays limited efficiency in AE treatment. Bioengineered nano cellular membrane vesicles are widely used for displaying the native conformational epitope peptides because of their unique structure and biocompatibility. In this study, four T-cells and four B-cells dominant epitope peptides of E. multilocularis with high immunogenicity were engineered into the Vero cell surface to construct a membrane vesicle nanovaccine for the treatment of AE. The results showed that the nanovesicle vaccine can efficiently activate dendritic cells, induce specific T/B cells to form a mutually activated circuit, and inhibit E. multilocularis infection. This study presents for the first time a nanovaccine strategy that can completely eliminate the burden of E. multilocularis.

Human Umbilical Cord Mesenchymal Stromal Cell-Derived Exosomes Alleviate Hypoxia-Induced Pulmonary Arterial Hypertension in Mice Via Macrophages.

Pulmonary hypertension (PH) is an intractable, severe, and progressive cardiopulmonary disease. Recent findings suggest that human umbilical cord mesenchymal stromal cells (HUCMSCs) and HUCMSC-derived exosomes (HUCMSC-Exos) possess potential therapeutic value for PH. However, whether they have beneficial effects on hypoxic pulmonary hypertension (HPH) is unclear. Exos are released into the extracellular environment by the fusion of intracellular multivesicular bodies with the cell membrane, and they play an important role in cellular communication. Exos ameliorate immune inflammation levels, alter macrophage phenotypes, regulate mitochondrial metabolic function, and inhibit pulmonary vascular remodeling, thereby improving PH. Macrophages are important sources of cytokines and other transmitters and can promote the release of cytokines, vasoactive molecules, and reactive oxygen species, all of which are associated with pulmonary vascular remodeling. Therefore, the aim of this study was to investigate whether HUCMSC-Exos could improve the lung inflammatory microenvironment and inhibit pulmonary vascular remodeling by targeting macrophages and identifying the underlying mechanisms. The results showed that HUCMSC-Exos promoted M2 macrophage polarization, decreased pro-inflammatory factors, increased IL-10 levels, and inhibited IL-33/ST2 axis expression, thereby inhibiting hypoxia-induced proliferation of pulmonary artery smooth muscle cells and ameliorating HPH.

[Research progress on the effect of mitochondrial and endoplasmic reticulum stress caused by hypoxia during pregnancy on preeclampsia and intrauterine growth restriction].

Preeclampsia and intrauterine growth restriction (IUGR) of the fetus are the two most common pregnancy complications worldwide, affecting 5%-10% of pregnant women. Preeclampsia is associated with significantly increased maternal and fetal morbidity and mortality. Hypoxia-induced uteroplacental dysfunction is now recognized as a key pathological factor in preeclampsia and IUGR. Reduced oxygen supply (hypoxia) disrupts mitochondrial and endoplasmic reticulum (ER) function. Hypoxia has been shown to alter mitochondrial reactive oxygen species (ROS) homeostasis and induce ER stress. Hypoxia during pregnancy is associated with excessive production of ROS in the placenta, leading to oxidative stress. Oxidative stress occurs in a number of human diseases, including high blood pressure during pregnancy. Studies have shown that uterine placental tissue/cells in preeclampsia and IUGR show high levels of oxidative stress, which plays an important role in the pathogenesis of both the complications. This review summarizes the role of hypoxia-induced mitochondrial oxidative stress and ER stress in the pathogenesis of preeclampsia/IUGR and discusses the potential therapeutic strategies targeting oxidative stress to treat both the pregnancy complications.

High-Altitude Hypoxia Induces Excessive Erythrocytosis in Mice via Upregulation of the Intestinal HIF2a/Iron-Metabolism Pathway.

Excessive erythrocytosis (EE) is a preclinical form of chronic mountain sickness (CMS). The dysregulation of iron metabolism in high-altitude hypoxia may induce EE. The intestinal hypoxia-inducible factor 2 alpha (HIF2a) regulates the genes involved in iron metabolism. Considering these findings, we aimed to investigate the function and mechanism of intestinal HIF2α and the iron metabolism pathway in high-altitude EE mice. C57BL/6J mice were randomized into four groups: the low-altitude group, the high-altitude group, the high-altitude + HIF2α inhibitor group, and the high-altitude + vehicle group. In-vitro experiments were performed using the human intestinal cell line HCT116 cultured under hypoxic conditions for 24 h. Results showed that high-altitude hypoxia significantly increased the expression of intestinal HIF2α and iron metabolism-related genes, including Dmt1, Dcytb, Fpn, Tfrc, and Fth in EE mice. Genetic blockade of the intestinal HIF2α-iron metabolism pathway decreased iron availability in HCT116 cells during hypoxia. The HIF2α inhibitor PT2385 suppressed intestinal HIF2α expression, decreased iron hypermetabolism, and reduced excessive erythrocytosis in mice. These data support the hypothesis that exposure to high-altitude hypoxia can lead to iron hypermetabolism by activating intestinal HIF2α transcriptional regulation, and reduced iron availability improves EE by inhibiting intestinal HIF2α signaling.

Brain-aging related protein expression and imaging characteristics of mice exposed to chronic hypoxia at high altitude.

Objective: To determine changes in protein expression related to brain aging and imaging features in mice after chronic hypoxia exposure at high altitude. Method: A total of 24 healthy 4-week-old mice were randomly divided into high altitude hypoxia (HH) and plain control (PC) groups (n = 8 per group). HH mice were transported from Xi'an (450 m above sea level) to Maduo (4,300 m above sea level) while PC mice were raised in Xi'an. After 6 months, 7.0T magnetic resonance imaging (MRI) was performed. All mice completed T2-weighted imaging (T2WI), diffusion tensor imaging (DTI), resting-state functional MRI (rs-fMRI), arterial spin labeling (ASL), and magnetic resonance angiography (MRA) examinations. Next, brain slices were prepared and Nissl staining was used to observe morphological changes in neurons. Ultrastructural changes in neurons were observed by transmission electron microscopy. Expression changes of Caspase-3, klotho, P16, P21, and P53 at the gene and protein levels were detected by real-time PCR (RT-PCR) and Western blot. Results: The number of neuronal Nissl bodies in the hippocampus and frontal cortex was significantly decreased in the HH group compared to the PC group. Some hippocampal and frontal cortical neurons were apoptotic, the nuclei were wrinkled, chromatin was aggregated, and most mitochondria were mildly swollen (crista lysis, fracture). Compared with the PC group, the HH group showed elevated expression of caspase-3 mRNA, P16 mRNA, P21 mRNA, and P53 mRNA in the hippocampus and frontal cortex. Expression of Klotho mRNA in the frontal cortex was also significantly decreased. Western blot results showed that caspase-3 protein expression in the hippocampus and frontal cortex of the HH group was increased compared with the PC group. Moreover, there was decreased Klotho protein expression and significantly increased P-P53 protein expression. Compared with the PC group, expression of P16 protein in the frontal cortex of the HH group was increased and the gray matter (GM) volume in the left visceral area, left caudate nucleus, and left piriform cortex was decreased. Furthermore, the amplitude of low frequency fluctuation was decreased in the left posterior nongranular insular lobe, right small cell reticular nucleus, left flocculus, left accessory flocculus, and left primary auditory area, but increased in the GM layer of the left superior colliculus. Regional homogeneity was decreased in the left and right olfactory regions, but increased in the left bed nucleus. After exposure to high altitude, functional connectivity (FC) between the bilateral caudate nucleus and thalamus, corpus callosum, cingulate gyrus, anterior limbic cortex, globus pallidus, and hippocampus was weakened. FC between the right caudate nucleus and hypothalamus and entorhinal cortex was also weakened. The fractional anisotropy value of the left hippocampus was decreased in the HH group. Compared with the PC group, the HH group showed significantly increased inner diameters of the bilateral common carotid artery and left internal carotid artery. The cerebral blood flow values of the bilateral cortex and bilateral hippocampus in the HH group did not change significantly. Conclusion: Taken together, our findings show that chronic hypoxia exposure at high altitude may promote neuronal apoptosis and abnormal expression of related proteins, changing the structure and function of brain. These changes may contribute to brain aging.

Macrophage-derived inflammation promotes pulmonary vascular remodeling in hypoxia-induced pulmonary arterial hypertension mice.

The role of inflammation in pulmonary hypertension is gradually gaining increasing research attention. However, no previous study has evaluated the characteristics of inflammation during chronic hypoxia-induced pulmonary hypertension. Therefore, the aim of this study was to investigate the characteristics of the inflammatory process involved in hypoxia-induced pulmonary hypertension in mice. The current study evaluated from day 4 to day 28 of hypoxia, the PAAT and PAAT/PET decreased, accompanied by pulmonary vascular remodeling and right ventricular hypertrophy, as well as increased numbers of CD68 macrophages. The expression of the pro-inflammatory factors IL-1ß and IL-33 increased, but decreased on day 28. The expression of IL-12 increased from day 4 to day 28, whereas that of the anti-inflammatory factor IL-10 in lung tissue decreased. Furthermore, the expression of the IL-33/ST2 signaling pathway also increased over time under hypoxic conditions. In conclusion, pulmonary artery remodeling in HPH mice worsens progressively in a time-dependent manner, with inflammatory cell infiltration predominating in the early stage and pulmonary vascular remodeling occurring in the later stage.

Platelets in Renal Disease.

Kidney disease is a major global health concern, affecting millions of people. Nephrologists have shown interest in platelets because of coagulation disorders caused by renal diseases. With a better understanding of platelets, it has been found that these anucleate and abundant blood cells not only play a role in hemostasis, but also have important functions in inflammation and immunity. Platelets are not only affected by kidney disease, but may also contribute to kidney disease progression by mediating inflammation and immune effects. This review summarizes the current evidence regarding platelet abnormalities in renal disease, and the multiple effects of platelets on kidney disease progression. The relationship between platelets and kidney disease is still being explored, and further research can provide mechanistic insights into the relationship between thrombosis, bleeding, and inflammation related to kidney disease, and elucidate targeted therapies for patients with kidney disease.

Antibiotic intervention exacerbated oxidative stress and inflammatory responses in SD rats under hypobaric hypoxia exposure.

The gut microbiota plays a crucial role in maintaining host nutrition, metabolism, and immune homeostasis, particularly in extreme environmental conditions. However, the regulatory mechanisms of the gut microbiota in animal organisms hypobaric hypoxia exposure require further study. We conducted a research by comparing SD rats treated with an antibiotic (ABX) cocktail and untreated SD rats that were housed in a low-pressure oxygen chamber (simulating low pressure and hypoxic environment at 6000 m altitude) for 30 days. After the experiment, blood, feces, and lung tissues from SD rats were collected for analysis of blood, 16S rRNA amplicon sequencing, and non-targeted metabolomics. The results demonstrated that the antibiotic cocktail-treated SD rats exhibited elevated counts of neutrophil (Neu) and monocyte (Mon) cells, an enrichment of sulfate-reducing bacteria (SBC), reduced levels of glutathione, and accumulated phospholipid compounds. Notably, the accumulation of phospholipid compounds, particularly lysophosphatidic acid (LPA), lipopolysaccharide (LPS), and lysophosphatidylcholine (LPC), along with the aforementioned changes, contributed to heightened oxidative stress and inflammation in the organism. In addition, we explored the resistance mechanisms of SD rats in low-oxygen and low-pressure environments and found that increasing the quantity of the Prevotellaceae and related beneficial bacteria (especially Lactobacillus) could reduce oxidative stress and inflammation. These findings offer valuable insights into enhancing the adaptability of low-altitude animals under hypobaric hypoxia exposure.

Mitochondria in hypoxic pulmonary hypertension, roles and the potential targets.

Mitochondria are the centrol hub for cellular energy metabolisms. They regulate fuel metabolism by oxygen levels, participate in physiological signaling pathways, and act as oxygen sensors. Once oxygen deprived, the fuel utilizations can be switched from mitochondrial oxidative phosphorylation to glycolysis for ATP production. Notably, mitochondria can also adapt to hypoxia by making various functional and phenotypes changes to meet the demanding of oxygen levels. Hypoxic pulmonary hypertension is a life-threatening disease, but its exact pathgenesis mechanism is still unclear and there is no effective treatment available until now. Ample of evidence indicated that mitochondria play key factor in the development of hypoxic pulmonary hypertension. By hypoxia-inducible factors, multiple cells sense and transmit hypoxia signals, which then control the expression of various metabolic genes. This activation of hypoxia-inducible factors considered associations with crosstalk between hypoxia and altered mitochondrial metabolism, which plays an important role in the development of hypoxic pulmonary hypertension. Here, we review the molecular mechanisms of how hypoxia affects mitochondrial function, including mitochondrial biosynthesis, reactive oxygen homeostasis, and mitochondrial dynamics, to explore the potential of improving mitochondrial function as a strategy for treating hypoxic pulmonary hypertension.

Erythrocytes Display Metabolic Changes in High-Altitude Polycythemia.

Qile, Muge, Qiying Xu, Yi Ye, Huifang Liu, Drolma Gomchok, Juanli Liu, Tana Wuren, and Ri-Li Ge. Erythrocytes display metabolic changes in high-altitude polycythemia. High Alt Med Biol. 24:104-109, 2023. Background: Sphingosine-1-phosphate (S1P) levels are increased after acute exposure to high altitude; however, whether this effect is observed in chronic high-altitude hypoxia is unknown. Methods: We studied erythrocyte S1P levels in 13 subjects with high-altitude polycythemia (HAPC) and 13 control subjects and also used a mouse model of HAPC. HAPC subjects lived in Maduo (4,300 m altitude) for 10 years, whereas control subjects lived permanently in Xining (2,260 m). The mouse model of HAPC was established by stimulating an altitude of 5,000 m in a hypobaric chamber for 30 days. Hematology and S1P, CD73, 2,3-bisphosphoglycerate (2,3-BPG), and reticulocyte levels were measured. Results: The hemoglobin concentration and number of red blood cells were significantly elevated in human and mouse HAPC groups. Blood S1P levels in HAPC subjects and mice were higher than those in control groups (p < 0.05 and p < 0.001, respectively). 2,3-BPG and CD73 levels in HAPC subjects were significantly higher than those in control subjects (p < 0.05). No significant changes in reticulocyte levels were observed. Conclusions: The critical altitude-induced metabolic changes such as S1P retained high levels even after prolonged exposure, and it may inspire future research into therapeutic strategies for hypoxia-associated illnesses.

[Factors affecting pulmonary arterial pressure in response to high-altitude hypoxic stress].

The alteration of pulmonary artery pressure is an important physiological indicator to reflect the organism's adaptation to acclimatization or the pathological injury in response to high-altitude hypoxic environment. The effects of hypoxic stress at different altitudes for different time on pulmonary artery pressure are different. There are many factors involved in the changes of pulmonary artery pressure, such as the contraction of pulmonary arterial smooth muscle, hemodynamic changes, abnormal regulation of vascular activity and abnormal changes of cardiopulmonary function. Understanding of the regulatory factors of pulmonary artery pressure in hypoxic environment is crucial in clarifying the relevant mechanisms of hypoxic adaptation, acclimatization, prevention, diagnosis, treatment and prognosis of acute and chronic high-altitude diseases. In recent years, great progress has been made in the study regarding the factors affecting pulmonary artery pressure in response to high-altitude hypoxic stress. In this review, we discuss the regulatory factors and intervention measures of pulmonary arterial hypertension induced by hypoxia from the aspects of hemodynamics of circulatory system, vasoactive state and changes of cardiopulmonary function.