Chronic intermittent hypoxia-induced mitochondrial dysfunction mediates endothelial injury via the TXNIP/NLRP3/IL-1β signaling pathway

Cytosolic Escape of Mitochondrial DNA Triggers cGAS-STING Pathway-Dependent Neuronal PANoptosis in Response to Intermittent Hypoxia

Intermittent hypoxia (IH) is the predominant pathophysiological disturbance in obstructive sleep apnea (OSA), characterized by neuronal cell death and neurocognitive impairment. We focus on the accumulated mitochondrial DNA (mtDNA) in the cytosol, which acts as a damage-associated molecular pattern (DAMP) and activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, a known trigger for immune responses and neuronal death in degenerative diseases. However, the specific role and mechanism of the mtDNA-cGAS-STING axis in IH-induced neural damage remain largely unexplored. Here, we investigated the involvement of PANoptosis, a novel type of programmed cell death linked to cytosolic mtDNA accumulation and the cGAS-STING pathway activation, in neuronal cell death induced by IH. Our study found that PANoptosis occurred in primary cultures of hippocampal neurons and HT22 cell lines exposed to IH. In addition, we discovered that during IH, mtDNA released into the cytoplasm via the mitochondrial permeability transition pore (mPTP) activates the cGAS-STING pathway, exacerbating PANoptosis-associated neuronal death. Pharmacologically inhibiting mPTP opening or depleting mtDNA significantly reduced cGAS-STING pathway activation and PANoptosis in HT22 cells under IH. Moreover, our findings indicated that the cGAS-STING pathway primarily promotes PANoptosis by modulating endoplasmic reticulum (ER) stress. Inhibiting or silencing the cGAS-STING pathway substantially reduced ER stress-mediated neuronal death and PANoptosis, while lentivirus-mediated STING overexpression exacerbated these effects. In summary, our study elucidates that cytosolic escape of mtDNA triggers cGAS-STING pathway-dependent neuronal PANoptosis in response to IH, mainly through regulating ER stress. The discovery of the novel mechanism provides theoretical support for the prevention and treatment of neuronal damage and cognitive impairment in patients with OSA.

Reactive oxygen species in hypertension

Hypertension is a leading risk factor for stroke, heart disease and chronic kidney disease. Multiple interacting factors and organ systems increase blood pressure and cause target-organ damage. Among the many molecular elements involved in the development of hypertension are reactive oxygen species (ROS), which influence cellular processes in systems that contribute to blood pressure elevation (such as the cardiovascular, renal, immune and central nervous systems, or the renin-angiotensin-aldosterone system). Dysregulated ROS production (oxidative stress) is a hallmark of hypertension in humans and experimental models. Of the many ROS-generating enzymes, NADPH oxidases are the most important in the development of hypertension. At the cellular level, ROS influence signalling pathways that define cell fate and function. Oxidative stress promotes aberrant redox signalling and cell injury, causing endothelial dysfunction, vascular damage, cardiovascular remodelling, inflammation and renal injury, which are all important in both the causes and consequences of hypertension. ROS scavengers reduce blood pressure in almost all experimental models of hypertension; however, clinical trials of antioxidants have yielded mixed results. In this Review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in hypertension. We focus on cellular sources of ROS, molecular mechanisms of oxidative stress and alterations in redox signalling in organ systems, and their contributions to hypertension.

Ocular Inflammation and Oxidative Stress as a Result of Chronic Intermittent Hypoxia: A Rat Model of Sleep Apnea

Obstructive sleep apnea (OSA) is a sleep disorder characterized by intermittent complete or partial occlusion of the airway. Despite a recognized association between OSA and glaucoma, the nature of the underlying link remains unclear. In this study, we investigated whether mild OSA induces morphological, inflammatory, and metabolic changes in the retina resembling those seen in glaucoma using a rat model of OSA known as chronic intermittent hypoxia (CIH). Rats were randomly assigned to either normoxic or CIH groups. The CIH group was exposed to periodic hypoxia during its sleep phase with oxygen reduction from 21% to 10% and reoxygenation in 6 min cycles over 8 h/day. The eyes were subsequently enucleated, and then the retinas were evaluated for retinal ganglion cell number, oxidative stress, inflammatory markers, metabolic changes, and hypoxic response modulation using immunohistochemistry, multiplex assays, and capillary electrophoresis. Statistically significant differences were observed between normoxic and CIH groups for oxidative stress and inflammation, with CIH resulting in increased HIF-1α protein levels, higher oxidative stress marker 8-OHdG, and increased TNF-α. Pyruvate dehydrogenase kinase-1 protein was significantly reduced with CIH. No significant differences were found in retinal ganglion cell number. Our findings suggest that CIH induces oxidative stress, inflammation, and upregulation of HIF-1α in the retina, akin to early-stage glaucoma.

Obstructive sleep apnea hypopnea syndrome and vascular lesions: An update on what we currently know

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the most prevalent sleep and respiratory disorder. This syndrome can induce severe cardiovascular and cerebrovascular complications, and intermittent hypoxia is a pivotal contributor to this damage. Vascular pathology is closely associated with the impairment of target organs, marking a focal point in current research. Vascular lesions are the fundamental pathophysiological basis of multiorgan ailments and indicate a shared pathogenic mechanism among common cardiovascular and cerebrovascular conditions, suggesting their importance as a public health concern. Increasing evidence shows a strong correlation between OSAHS and vascular lesions. Previous studies predominantly focused on the pathophysiological alterations in OSAHS itself, such as intermittent hypoxia and fragmented sleep, leading to vascular disruptions. This review aims to delve deeper into the vascular lesions affected by OSAHS by examining the microscopic pathophysiological mechanisms involved. Emphasis has been placed on examining how OSAHS induces vascular lesions through disruptions in the endothelial barrier, metabolic dysregulation, cellular phenotype alterations, neuroendocrine irregularities, programmed cell death, vascular inflammation, oxidative stress and epigenetic modifications. This review examines the epidemiology and associated risk factors for OSAHS and vascular diseases and subsequently describes the existing evidence on vascular lesions induced by OSAHS in the cardiovascular, cerebrovascular, retinal, renal and reproductive systems. A detailed account of the current research on the pathophysiological mechanisms mediating vascular lesions caused by OSAHS is provided, culminating in a discussion of research advancements in therapeutic modalities to mitigate OSAHS-related vascular lesions and the implications of these treatment strategies.

Mito-Tempo alleviates ox-LDL-provoked foam cell formation by regulating Nrf2/NLRP3 signaling

Our previous studies have demonstrated that Mito-Tempol (also known as 4-hydroxy-Tempo), a mitochondrial reactive oxygen species scavenger, alleviates oxidized low-density lipoprotein (ox-LDL)-triggered foam cell formation. Given the effect of oxidative stress on activating the NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome, which promotes foam cell formation, we aimed to explore whether Mito-Tempo inhibits ox-LDL-triggered foam cell formation by regulating NLRP3 inflammasome. The results revealed that Mito-Tempo re-activated Nrf2 and alleviated macrophage foam cell formation induced by ox-LDL, whereas the effects were reversed by ML385 (a specific Nrf2 inhibitor). Mito-Tempo restored the expression and nuclear translocation of Nrf2 by decreasing ox-LDL-induced ubiquitination. Furthermore, Mito-Tempo suppressed ox-LDL-triggered NLRP3 inflammasome activation and subsequent pyroptosis, whereas the changes were blocked by ML385. Mito-Tempo decreased lipoprotein uptake by inhibiting CD36 expression and suppressed foam cell formation by regulating the NLRP3 inflammasome. Taken together, Mito-Tempo exhibits potent anti-atherosclerotic effects by regulating Nrf2/NLRP3 signaling.

Hypoxic preacclimatization combining intermittent hypoxia exposure with physical exercise significantly promotes the tolerance to acute hypoxia

Background: Both hypoxia exposure and physical exercise before ascending have been proved to promote high altitude acclimatization, whether the combination of these two methods can bring about a better effect remains uncertain. Therefore, we designed this study to evaluate the effect of hypoxic preacclimatization combining intermittent hypoxia exposure (IHE) and physical exercise on the tolerance to acute hypoxia and screen the optimal preacclimatization scheme among the lowlanders. Methods: A total of 120 Han Chinese young men were enrolled and randomly assigned into four groups, including the control group and three experimental groups with hypoxic preacclimatization of 5-day rest, 5-day exercise, and 3-day exercise in a hypobaric chamber, respectively. Main physical parameters for hypoxia acclimatization, AMS incidence, physical and mental capacity were measured for each participant in the hypobaric chamber simulated to the altitude of 4500 m in the effect evaluation stage. The effect was compared between different schemes. Results: During the effect evaluation stage, SpO2 of the 5-day rest group and 5-day exercise group was significantly higher than that of the control group (p = 0.001 and p = 0.006, respectively). The participants with 5-day rest had significantly lower HR than the controls (p = 0.018). No significant differences of AMS incidence were found among the four groups, while the proportion of AMS headache symptom (moderate and severe vs. mild) was significantly lower in the 3-day exercise group than that in the control group (p = 0.002). The 5-day exercise group had significantly higher VO2max, than the other three groups (p = 0.033, p < 0.001, and p = 0.023, respectively). The 5-day exercise group also had significantly higher digital symbol and pursuit aiming test scores, while shorter color selection reaction time than the control group (p = 0.005, p = 0.005, and p = 0.004, respectively). Conclusion: Hypoxic preacclimatization combining IHE with physical exercise appears to be efficient in promoting the tolerance to acute hypoxia. Hypoxia duration and physical exercise of moderate intensity are helpful for improvement of SpO2 and HR, relief of AMS headache symptoms, and enhancement of mental and physical operation capacity.

Endothelial downregulation of nuclear m6A reader YTHDC1 promotes pulmonary vascular remodeling in sugen hypoxia model of pulmonary hypertension

Background

Pulmonary hypertension (PH) is characterized with vascular remodeling, which is intiated by vascular endothelial dysfunction. N6-methyladenosine (m6A) modification mediates gene expression in many ways including mediating RNA degradation, splicing, nuclear export et al. m6A modification have been found to be associated with the development of PH. However, the role of m6A regulators in pulmonary artery endothelial cells (PAECs) dysfunction of PH is still under research.

Methods

The expression levels of m6A regulators in PAECs were analyzed with the single-cell sequencing Data(scRNA). Next, the target differentially expressed genes (DEGs) of m6A regulators in PAECs were functionally annotated. The analysis of cellular interactions included the examination of receptor-ligand pairs regulated by m6A regulators. Pseudo-time trajectory analyses and a ceRNA network involving lncRNAs, miRNAs, and mRNAs were conducted in PAECs. Furthermore, microarray data (GSE180169) for Sugen Hypoxia PH (SuHx PH) mouse models was screened for DEGs and m6A regulators in PAECs. Moreover, the expression of YTHDC1 in the lung samples of SuHx PH models was determined using immunofluorescence. In vitro, the mRNA expression of YTHDC1 in HPAECs under hypoxia conditions was detected. The effect of YTHDC1 recombinant protein on HPAEC proliferation was detected by Cell Counting Kit-8 (CCK8).

Results

Dysregulation of m6A regulators was observed in mouse PAECs. The m6A reader of YTHDC1 was decreased in PAECs in scRNA data and RNAseq data of isolated PAECs of SuHx PH models. Downregulation of YTHDC1 was caused by hypoxia in PAECs in vitro and similar results was observed in PAECs of SuHx PH mouse models. Next, YTHDC1 recombinant protein was found to inhibit HPAECs proliferation. The DEGs targeted by YTHDC1 were enriched in angiogenesis, endothelial cell migration, fluid shear stress, and stem cell maintenance. Analysis indicates that interactions among endothelial cells, smooth muscle cells, fibroblasts, and immune cells, mediated by specific YTHDC1 target genes (e.g., PTPRC-MRC1, ITBG2-ICAM1, COL4A1-CD44), contribute to PH development. Also, the YTHDC1 expression were consistent with Thioredoxin interacting protein (TXNIP). What's more, the predicted transcription factors showed that NFKB1, Foxd3 may be involved in the regulation of YTHDC1. Lastly, our data suggest that YTHDC1 may be involved in regulating PAECs dysfunction through lncRNA/miRNA/mRNA network.

Conclusion

For the first time, we analyzed changes in the expression and biological functions of m6A regulators in SuHx PH mouse models. We causatively linked YTHDC1 to PAECs dysfunction, providing novel insight into and opportunities to diagnose and treat PH.

Obstructive Sleep Apnea-Associated Intermittent Hypoxia-Induced Immune Responses in Males, Pregnancies, and Offspring

Obstructive sleep apnea (OSA), a respiratory sleep disorder associated with cardiovascular diseases, is more prevalent in men. However, OSA occurrence in pregnant women rises to a level comparable to men during late gestation, creating persistent effects on both maternal and offspring health. The exact mechanisms behind OSA-induced cardiovascular diseases remain unclear, but inflammation and oxidative stress play a key role. Animal models using intermittent hypoxia (IH), a hallmark of OSA, reveal several pro-inflammatory signaling pathways at play in males, such as TLR4/MyD88/NF-κB/MAPK, miRNA/NLRP3, and COX signaling, along with shifts in immune cell populations and function. Limited evidence suggests similarities in pregnancies and offspring. In addition, suppressing these inflammatory molecules ameliorates IH-induced inflammation and tissue injury, providing new potential targets to treat OSA-associated cardiovascular diseases. This review will focus on the inflammatory mechanisms linking IH to cardiovascular dysfunction in males, pregnancies, and their offspring. The goal is to inspire further investigations into the understudied populations of pregnant females and their offspring, which ultimately uncover underlying mechanisms and therapeutic interventions for OSA-associated diseases.

Cilostazol protects against degenerative cervical myelopathy injury and cell pyroptosis via TXNIP-NLRP3 pathway

Degenerative cervical myelopathy (DCM) is one of the most common and serious neurological diseases. Cilostazol has protective effects of anterior horn motor neurons and prevented the cell apoptosis. However, there was no literatures of Cilostazol on DCM. In this study, we established the DCM rat model to detect the effects of Cilostazol. Meanwhile, the neurobehavioral assessments, histopathology changes, inflammatory cytokines, Thioredoxin-interacting protein (TXNIP), NOD‑like receptor pyrin domain containing 3 (NLRP3) and pro-caspase-1 expressions were detected by Basso, Beattie, and Bresnahan score assessment, Hematoxylin and Eosin Staining, Enzyme-linked immunosorbent assay, immunofluorescence and Western blotting, respectively. After treated with Cilostazol, the Basso, Beattie, and Bresnahan (BBB) score, inclined plane test and forelimb grip strength in DCM rats were significantly increased meanwhile the histopathology injury and inflammatory cytokines were decreased. Additionally, TXNIP, NLRP3 and pro-caspase-1 expressions levels were decreased in Cilostazol treated DCM rats. Interestingly, the using of siTXNIP significantly changed inflammatory cytokines, TXNIP, NLRP3 and pro-caspase-1 expressions, however there was no significance between siTXNIP and Cilostazol + siTXNIP group. These observations showed that Cilostazol rescues DCM injury and ameliorates neuronal destruction mediated by TXNIP/NLRP3/caspase-1 and pro-inflammatory cytokines. As a result of our study, these findings provide further evidence that Cilostazol may represent promising therapeutic candidates for DCM.

Oxygen metabolism abnormality and Alzheimer's disease: An update

Oxygen metabolism abnormality plays a crucial role in the pathogenesis of Alzheimer's disease (AD) via several mechanisms, including hypoxia, oxidative stress, and mitochondrial dysfunction. Hypoxia condition usually results from living in a high-altitude habitat, cardiovascular and cerebrovascular diseases, and chronic obstructive sleep apnea. Chronic hypoxia has been identified as a significant risk factor for AD, showing an aggravation of various pathological components of AD, such as amyloid β-protein (Aβ) metabolism, tau phosphorylation, mitochondrial dysfunction, and neuroinflammation. It is known that hypoxia and excessive hyperoxia can both result in oxidative stress and mitochondrial dysfunction. Oxidative stress and mitochondrial dysfunction can increase Aβ and tau phosphorylation, and Aβ and tau proteins can lead to redox imbalance, thus forming a vicious cycle and exacerbating AD pathology. Hyperbaric oxygen therapy (HBOT) is a non-invasive intervention known for its capacity to significantly enhance cerebral oxygenation levels, which can significantly attenuate Aβ aggregation, tau phosphorylation, and neuroinflammation. However, further investigation is imperative to determine the optimal oxygen pressure, duration of exposure, and frequency of HBOT sessions. In this review, we explore the prospects of oxygen metabolism in AD, with the aim of enhancing our understanding of the underlying molecular mechanisms in AD. Current research aimed at attenuating abnormalities in oxygen metabolism holds promise for providing novel therapeutic approaches for AD.

Microglia dynamic response and phenotype heterogeneity in neural regeneration following hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury poses a significant threat to the neural niche within the central nervous system. In response to this pathological process, microglia, as innate immune cells in the central nervous system, undergo rapid morphological, molecular and functional changes. Here, we comprehensively review these dynamic changes in microglial response to hypoxic-ischemic brain injury under pathological conditions, including stroke, chronic intermittent hypoxia and neonatal hypoxic-ischemic brain injury. We focus on the regulation of signaling pathways under hypoxic-ischemic brain injury and further describe the process of microenvironment remodeling and neural tissue regeneration mediated by microglia after hypoxic-ischemic injury.

NLRP3/miR-223-3p axis attenuates neuroinflammation induced by chronic intermittent hypoxia

Obstructive sleep apnea (OSA) is mainly characterized by chronic intermittent hypoxia (CIH) with multiple brain injuries. Nucleotide oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is considered the most important factor inducing and maintaining inflammation. However, the role of NLRP3 and its underlying mechanism in CIH-elicited neuroinflammation remains unclear. We constructed an OSA-related CIH in vivo model and assessed the rats' cognitive behavior in the Morris water maze. The combination of miR-223-3p and NLRP3 was confirmed by the TargetScan database, double luciferase reporter gene experiment, and RNA immunoprecipitation (RIP) experiment. Western blot and ELISA assay were used to analyze the effects of miR-223-3p targeting NLRP3 on the expression of pyroptotic or inflammatory factors in vivo in CIH rats. Severe cognitive impairment was observed in rats at week 6 post-treatment, with increased inflammatory factors in the blood and hippocampus, heightened NLRP3 expression, and low miR-223-3p levels. And the good binding activity of the two was confirmed by dual luciferase reporter and RIP experiments. Next, we found that silencing NLRP3 or overexpression of miR-223-3p in the CIH model could improve cognitive deficits and reduce the level of proinflammatory factors and pyroptosis factors in rats. Finally, based on silencing NLRP3 or overexpression miR-223-3p, we confirmed that there was a regulatory relationship between miR-223-3p and NLRP3. Our results suggested that the NLRP3/ miR-223-3p axis played a role in attenuating CIH-induced neuroinflammation.

Microcirculation and Mitochondria: The Critical Unit

Critical illness is often accompanied by a hemodynamic imbalance between macrocirculation and microcirculation, as well as mitochondrial dysfunction. Microcirculatory disorders lead to abnormalities in the supply of oxygen to tissue cells, while mitochondrial dysfunction leads to abnormal energy metabolism and impaired tissue oxygen utilization, making these conditions important pathogenic factors of critical illness. At the same time, there is a close relationship between the microcirculation and mitochondria. We introduce here the concept of a "critical unit", with two core components: microcirculation, which mainly comprises the microvascular network and endothelial cells, especially the endothelial glycocalyx; and mitochondria, which are mainly involved in energy metabolism but perform other non-negligible functions. This review also introduces several techniques and devices that can be utilized for the real-time synchronous monitoring of the microcirculation and mitochondria, and thus critical unit monitoring. Finally, we put forward the concepts and strategies of critical unit-guided treatment.

Environmental and behavioral regulation of HIF-mitochondria crosstalk

Reduced oxygen availability (hypoxia) can lead to cell and organ damage. Therefore, aerobic species depend on efficient mechanisms to counteract detrimental consequences of hypoxia. Hypoxia inducible factors (HIFs) and mitochondria are integral components of the cellular response to hypoxia and coordinate both distinct and highly intertwined adaptations. This leads to reduced dependence on oxygen, improved oxygen supply, maintained energy provision by metabolic remodeling and tapping into alternative pathways and increased resilience to hypoxic injuries. On one hand, many pathologies are associated with hypoxia and hypoxia can drive disease progression, for example in many cancer and neurological diseases. But on the other hand, controlled induction of hypoxia responses via HIFs and mitochondria can elicit profound health benefits and increase resilience. To tackle pathological hypoxia conditions or to apply health-promoting hypoxia exposures efficiently, cellular and systemic responses to hypoxia need to be well understood. Here we first summarize the well-established link between HIFs and mitochondria in orchestrating hypoxia-induced adaptations and then outline major environmental and behavioral modulators of their interaction that remain poorly understood.

The role of microRNAs in pathophysiology and diagnostics of metabolic complications in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which is characterized by recurrent apneas and/or hypopneas occurring during sleep due to upper airway obstruction. Among a variety of health consequences, OSA patients are particularly susceptible to developing metabolic complications, such as metabolic syndrome and diabetes mellitus type 2. MicroRNAs (miRNAs) as epigenetic modulators are promising particles in both understanding the pathophysiology of OSA and the prediction of OSA complications. This review describes the role of miRNAs in the development of OSA-associated metabolic complications. Moreover, it summarizes the usefulness of miRNAs as biomarkers in predicting the aforementioned OSA complications.

Microglial exosomes alleviate intermittent hypoxia-induced cognitive deficits by suppressing NLRP3 inflammasome

Intermittent hypoxia is the best predictor of developing cognitive decline and Alzheimer's disease progression in patients with obstructive sleep apnea. The nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome has been poorly studied as a regulator of neuroinflammation in cognitive impairment caused by intermittent hypoxia. As critical inflammatory cells, exosomes secreted by microglia have been found to affect the spread of pathologic proteins and neuropathology in neurodegenerative diseases. However, the effects of microglial exosomes on neuroinflammation and cognitive outcomes after intermittent hypoxia remain unclear. In this study, the role of miRNAs in microglial exosomes in improving cognitive deficits in mice exposed to intermittent hypoxia was investigated. We demonstrated that miR-146a-5p fluctuated over time in microglial exosomes of mice exposed to intermittent hypoxia for different periods of time, which could regulate neuronal NLRP3 inflammasome and neuroinflammation. In primary neurons, we found that miR-146a-5p regulated mitochondrial reactive oxygen species by targeting HIF1α, thus affecting the NLRP3 inflammasome and secretion of inflammatory factors. Similarly, further studies showed that inhibition of NLRP3 by administering overexpressed miR-146a-5p in microglial exosomes and MCC950 has improved neuroinflammation and cognitive dysfunction in mice after intermittent hypoxia. In conclusion, NLRP3 inflammasome may be a regulatory target for ameliorating cognitive impairment caused by intermittent hypoxia, and microglial exosomal miR-146a-5p may be a promising therapeutic strategy.

Kartogenin-loaded hydrogel promotes intervertebral disc repair via protecting MSCs against reactive oxygen species microenvironment by Nrf2/TXNIP/NLRP3 axis

Intervertebral disc (IVD) degeneration (IDD) and the consequent low back pain present a major medical challenge. Stem cell-based tissue engineering is promising for the treatment of IDD. However, stem cell-based treatment is severely impaired by the increased generation of reactive oxygen species (ROS) in degenerative disc, which can lead to a high level of cell dysfunction and even death. In this study, a kartogenin (KGN)@PLGA-GelMA/PRP composite hydrogel was designed and used as a carrier of ADSCs-based therapies in disc repair. Injectable composite hydrogel act as a carrier for controlled release of KGN and deliver ADSCs to the degenerative disc. The released KGN can stimulate the differentiation of ADSCs into a nucleus pulposus (NP) -like phenotype and boost antioxidant capacity of ADSCs via activating Nrf2/TXNIP/NLRP3 axis. Furthermore, the composite hydrogel combined with ADSCs attenuated the in vivo degeneration of rat IVDs, maintained IVD tissue integrity and accelerated the synthesis of NP-like extracellular matrix. Therefore, the KGN@PLGA-GelMA/PRP composite hydrogel is a promising strategy for stem cell-based therapies of IDD.

Canagliflozin inhibits inflammasome activation in diabetic endothelial cells - Revealing a novel calcium-dependent anti-inflammatory effect of canagliflozin on human diabetic endothelial cells

BACKGROUND

Canagliflozin (CANA) shows anti-inflammatory and anti-oxidative effects on endothelial cells (ECs). In diabetes mellitus (DM), excessive reactive oxygen species (ROS) generation, increased intracellular calcium (Ca²⁺) and enhanced extracellular signal regulated kinase (ERK) 1/2 phosphorylation are crucial precursors for inflammasome activation. We hypothesized that: (1) CANA prevents the TNF-α triggered ROS generation in ECs from diabetic donors and in turn suppresses the inflammasome activation; and (2) the anti-inflammatory effect of CANA is mediated via intracellular Ca²⁺ and ERK1/2.

METHODS

Human coronary artery endothelial cells from donors with DM (D-HCAECs) were pre-incubated with either CANA or vehicle for 2 h before exposure to 50 ng/ml TNF-α for 2-48 h. NAC was applied to scavenge ROS, BAPTA-AM to chelate intracellular Ca²⁺, and PD 98059 to inhibit the activation of ERK1/2. Live cell imaging was performed at 6 h to measure ROS and intracellular Ca²⁺. At 48 h, ELISA and infra-red western blot were applied to detect IL-1β, NLRP3, pro-caspase-1 and ASC.

RESULTS

10 µM CANA significantly reduced TNF-α related ROS generation, IL-1β production and NLRP3 expression (P all <0.05), but NAC did not alter the inflammasome activation (P > 0.05). CANA and BAPTA both prevented intracellular Ca²⁺ increase in cells exposed to TNF-α (P both <0.05). Moreover, BAPTA and PD 98059 significantly reduced the TNF-α triggered IL-1β production as well as NLRP3 and pro-caspase-1 expression (P all <0.05).

CONCLUSION

CANA suppresses inflammasome activation by inhibition of (1) intracellular Ca²⁺ and (2) ERK1/2 phosphorylation, but not by ROS reduction.

Ginsenoside Rg1 ameliorates chronic intermittent hypoxia-induced vascular endothelial dysfunction by suppressing the formation of mitochondrial reactive oxygen species through the calpain-1 pathway

Background

As the major pathophysiological feature of obstructive sleep apnea (OSA), chronic intermittent hypoxia (CIH) is vital for the occurrence of cardiovascular complications. The activation of calpain-1 mediates the production of endothelial reactive oxygen species (ROS) and impairs nitric oxide (NO) bioavailability, resulting in vascular endothelial dysfunction (VED). Ginsenoside Rg1 is thought to against endothelial cell dysfunction, but the potential mechanism of CIH-induced VED remains unclear.

Methods

C57BL/6 mice and human coronary artery endothelial cells (HCAECs) were exposed to CIH following knockout or overexpression of calpain-1. The effect of ginsenoside Rg1 on VED, oxidative stress, mitochondrial dysfunction, and the expression levels of calpain-1, PP2A and p-eNOS were detected both in vivo and in vitro.

Results

CIH promoted VED, oxidative stress and mitochondrial dysfunction accompanied by enhanced levels of calpain-1 and PP2A and reduced levels of p-eNOS in mice and cellular levels. Ginsenoside Rg1, calpain-1 knockout, OKA, NAC and TEMPOL treatment protected against CIH-induced VED, oxidative stress and mitochondrial dysfunction, which is likely concomitant with the downregulated protein expression of calpain-1 and PP2A and the upregulation of p-eNOS in mice and cellular levels. Calpain-1 overexpression increased the expression of PP2A, reduced the level of p-eNOS, and accelerated the occurrence and development of VED, oxidative stress and mitochondrial dysfunction in HCAECs exposed to CIH. Moreover, scavengers of O₂ ^{• -}, H₂O₂, complex Ⅰ or mitoK_ATP abolished CIH-induced impairment in endothelial-dependent relaxation.

Conclusion

Ginsenoside Rg1 may alleviate CIH-induced vascular endothelial dysfunction by suppressing the formation of mitochondrial reactive oxygen species through the calpain-1 pathway.

CircRNA expression profiles and functional analysis in a mouse model of chronic intermittent hypoxia-induced renal injury: new insight into pathogenesis

Increasing evidence has demonstrated that circular RNAs (circRNAs) play crucial roles in the pathogenesis of multiple diseases. However, the functions of circRNAs in renal injury induced by obstructive sleep apnea (OSA) are poorly understood. The aim of this current study is to identify the global changes of circRNAs expression in OSA-induced renal damage. The mouse model of OSA treated by chronic intermittent hypoxia (CIH) was established. We assessed the expression profiles of circRNAs in CIH caused renal injury by microarray analysis. Bioinformatic analyses were further performed by us to assess those differentially expressed circRNAs. Quantitative realtime PCR (qRT-PCR) were then conducted to assure the data of microarray. Finally, a circRNA-miRNA -mRNA competing endogenous RNA (ceRNA) regulatory network was constructed. We found 11 upregulated and 13 downregulated circRNAs in CIH-induced renal injury. The qRT-PCR validated that the six selected circRNAs were identical to the results of microarray. Both Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were further employed to annotate the potential functions of dysregulated circRNAs. Finally, we established a ceRNA network to predict the target genes of circRNAs. In general, our results first illustrate that circRNAs are aberrantly expressed in OSA-induced renal injury, which might aid in offering novel genetic insights into this disease and potential therapeutic targets for OSA-associated chronic kidney disease.

Comparative Transcriptome Analysis of Head Kidney of Aeromonas hydrophila-infected Hypoxia-tolerant and Normal Large Yellow Croaker

The large yellow croaker (Larimichthys crocea) is one of the most economically important marine fish on the southeast coast of China and much of its yield is usually lost by hypoxia. To address this problem and lay a foundation for culturing a new strain of large yellow croaker with hypoxia tolerance, our research group screened a hypoxia-tolerant population of L. crocea. Surprisingly, we also found that hypoxia-tolerant population exhibited higher survival when infected with pathogens compared to the normal population during the farming operation. In order to understand the mechanism underlying the higher survival rate of the hypoxia-tolerant population and enrich the head kidney immune mechanism of L. crocea infected with pathogens, we compared and analyzed the head kidney transcriptome of the hypoxia-tolerant and normal individuals under Aeromonas hydrophila infection. We obtained 159.68 GB high-quality reads, of which more than 87.61% were successfully localized to the reference genome of L. crocea. KEGG analysis revealed differentially expressed genes in the signaling pathways involving immunity, cell growth and death, transport and catabolism, and metabolism. Among these, the toll-like receptor signaling pathway, Nod-like receptor signaling pathway, cytokine-cytokine receptor interaction, phagosome, apoptosis, and OXPHOS pathways were enriched in both groups after infection compared to before, and were enriched in infected tolerant individuals compared to normal individuals. In addition, we found that the expression of hif1α and its downstream genes were higher in the hypoxia-sensitive group of fish than in the normal group. In conclusion, our results showed some signaling pathways and hub genes, which may participate in A. hydrophila defense in the head kidney of two populations, and may contribute to the higher survival rate in the hypoxia-tolerant population. Overall, these findings increase our understanding of the defense mechanism within the head kidney of L. crocea under A. hydrophila infection, and suggest a preliminary hypothesis for why hypoxia-tolerant individuals may exhibit a higher survival rates after infection. Our study provides scientific evidence for the breeding of a new hypoxia-tolerant strain of L. crocea for aquaculture.

Activation of LRP1 Ameliorates Cerebral Ischemia/Reperfusion Injury and Cognitive Decline by Suppressing Neuroinflammation and Oxidative Stress through TXNIP/NLRP3 Signaling Pathway in Mice

Cerebral ischemia/reperfusion (I/R) injury is a clinical event associated with high morbidity and mortality. Neuroinflammation plays a crucial role in the pathogenesis of I/R-induced brain injury and cognitive decline. Low-density lipoprotein receptor-related protein-1 (LRP1) can exert strong neuroprotection in experimental intracerebral hemorrhage. However, whether LRP1 can confer neuroprotective effects after cerebral I/R is yet to be elucidated. The present study is aimed at investigating the effects of LRP1 activation on cerebral I/R injury and deducing the underlying mechanism involving TXNIP/NLRP3 signaling pathway. Cerebral I/R injury was induced in mice by bilateral common carotid artery occlusion. LPR1 ligand, apoE-mimic peptide COG1410, was administered intraperitoneally. To elucidate the underlying mechanism, overexpression of TXNIP was achieved via the hippocampal injection of AAV-TXNIP before COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, Western blot, enzyme-linked immunosorbent assay, HE, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed. Our results showed that the expressions of endogenous LRP1, TXNIP, NLRP3, procaspase-1, and cleaved caspase-1 were increased after cerebral I/R. COG1410 significantly ameliorated cerebral I/R-induced neurobehavioral deficits, brain edema, histopathological damage, and poor survival rate. Interestingly, COG1410 inhibited microglia proinflammatory polarization and promoted anti-inflammatory polarization, decreased oxidative stress, attenuated apoptosis, and inhibited the expression of the TXNIP/NLRP3 signaling pathway. However, the benefits of COG1410 were abolished by TXNIP overexpression. Thus, our study suggested that LRP1 activation with COG1410 attenuated cerebral I/R injury at least partially related to modulating microglial polarization through TXNIP/NLRP3 signaling pathway in mice. Thus, COG1410 treatment might serve as a promising therapeutic approach in the management of cerebral I/R patients.

Mitochondrial ROS drive resistance to chemotherapy and immune-killing in hypoxic non-small cell lung cancer

Background

Solid tumors subjected to intermittent hypoxia are characterized by resistance to chemotherapy and immune-killing by effector T-lymphocytes, particularly tumor-infiltrating Vγ9Vδ2 T-lymphocytes. The molecular circuitries determining this double resistance are not known.

Methods

We analyzed a panel of 28 human non-small cell lung cancer (NSCLC) lines, using an in vitro system simulating continuous and intermittent hypoxia. Chemosensitivity to cisplatin and docetaxel was evaluated by chemiluminescence, ex vivo Vγ9Vδ2 T-lymphocyte expansion and immune-killing by flow cytometry. Targeted transcriptomics identified efflux transporters and nuclear factors involved in this chemo-immuno-resistance. The molecular mechanism linking Hypoxia-inducible factor-1α (HIF-1α), CCAAT/Enhancer Binding Protein-β (C/EBP-β) isoforms LAP and LIP, ABCB1, ABCC1 and ABCA1 transporters were evaluated by immunoblotting, RT-PCR, RNA-IP, ChIP. Oxidative phosphorylation, mitochondrial ATP, ROS, depolarization, O₂ consumption were monitored by spectrophotometer and electronic sensors. The role of ROS/HIF-1α/LAP axis was validated in knocked-out or overexpressing cells, and in humanized (Hu-CD34⁺NSG) mice bearing LAP-overexpressing tumors. The clinical meaning of LAP was assessed in 60 NSCLC patients prospectively enrolled, treated with chemotherapy.

Results

By up-regulating ABCB1 and ABCC1, and down-regulating ABCA1, intermittent hypoxia induced a stronger chemo-immuno-resistance than continuous hypoxia in NSCLC cells. Intermittent hypoxia impaired the electron transport chain and reduced O₂ consumption, increasing mitochondrial ROS that favor the stabilization of C/EBP-β mRNA mediated by HIF-1α. HIF-1α/C/EBP-β mRNA binding increases the splicing of C/EBP-β toward the production of LAP isoform that transcriptionally induces ABCB1 and ABCC1, promoting the efflux of cisplatin and docetaxel. LAP also decreases ABCA1, limiting the efflux of isopentenyl pyrophosphate, i.e. the endogenous activator of Vγ9Vδ2 T-cells, and reducing the immune-killing. In NSCLC patients subjected to cisplatin-based chemotherapy, C/EBP-β LAP was abundant in hypoxic tumors and was associated with lower response to treatment and survival. LAP-overexpressing tumors in Hu-CD34⁺NSG mice recapitulated the patients’ chemo-immuno-resistant phenotype. Interestingly, the ROS scavenger mitoquinol chemo-immuno-sensitized immuno-xenografts, by disrupting the ROS/HIF-1α/LAP cascade.

Conclusions

The impairment of mitochondrial metabolism induced by intermittent hypoxia increases the ROS-dependent stabilization of HIF-1α/LAP complex in NSCLC, producing chemo-immuno-resistance. Clinically used mitochondrial ROS scavengers may counteract such double resistance. Moreover, we suggest C/EBP-β LAP as a new predictive and prognostic factor in NSCLC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02447-6.

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

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

Comprehensive Analysis of N6-Methyladenosine Regulators in the Subcluster Classification and Drug Candidates Prediction of Severe Obstructive Sleep Apnea

Background: Obstructive sleep apnea (OSA) is the most common type of sleep apnea that impacts the development or progression of many other disorders. Abnormal expression of N6-methyladenosine (m6A) RNA modification regulators have been found relating to a variety of human diseases. However, it is not yet known if m6A regulators are involved in the occurrence and development of OSA. Herein, we aim to explore the impact of m6A modification in severe OSA.

Methods: We detected the differentially expressed m6A regulators in severe OSA microarray dataset GSE135917. The least absolute shrinkage and selection operator (LASSO) and support vector machines (SVM) were used to identify the severe OSA-related m6A regulators. Receiver operating characteristic (ROC) curves were performed to screen and verify the diagnostic markers. Consensus clustering algorithm was used to identify m6A patterns. And then, we explored the character of immune microenvironment, molecular functionals, protein-protein interaction networks and miRNA-TF coregulatory networks for each subcluster. Finally, the Connectivity Map (CMap) tools were used to tailor customized treatment strategies for different severe OSA subclusters. An independent dataset GSE38792 was used for validation.

Results: We found that HNRNPA2B1, KIAA1429, ALKBH5, YTHDF2, FMR1, IGF2BP1 and IGF2BP3 were dysregulated in severe OSA patients. Among them, IGF2BP3 has a high diagnostic value in both independent datasets. Furthermore, severe OSA patients can be accurately classified into three m6A patterns (subcluster1, subcluster2, subcluster3). The immune response in subcluster3 was more active because it has high M0 Macrophages and M2 Macrophages infiltration and up-regulated human leukocyte antigens (HLAs) expression. Functional analysis showed that representative genes for each subcluster in severe OSA were assigned to histone methyltransferase, ATP synthesis coupled electron transport, virus replication, RNA catabolic, multiple neurodegeneration diseases pathway, et al. Moreover, our finding demonstrated cyclooxygenase inhibitors, several of adrenergic receptor antagonists and histamine receptor antagonists might have a therapeutic effect on severe OSA.

Conclusion: Our study presents an overview of the expression pattern and crucial role of m6A regulators in severe OSA, which may provide critical insights for future research and help guide appropriate prevention and treatment options.

Salidroside attenuates high altitude hypobaric hypoxia-induced brain injury in mice via inhibiting NF-κB/NLRP3 pathway

Salidroside (Sal), an active ingredient from Rhodiola crenulate, has been reported to exert neuroprotection in cerebral injury from hypobaric hypoxia (HH) at high altitude. However, it remains to be understood whether its protective effects are related to inflammation suppression. In the present work, we aimed to reveal the mechanism of Sal attenuating HH-induced brain injury in mice caused by an animal hypobaric and hypoxic chamber. Our results provided that Sal could attenuate HH-evoked pathological injury and oxidative stress response by decreasing the content of ROS and MDA, and elevating the activities of SOD and GSH-Px. Sal treatment could partly enhance the energy metabolism, evidenced by increasing the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, ATP, SDH, HK and PK, while decreasing the release of LDH and LD. Meanwhile, Sal administration reversed the degradation of tight junction proteins ZO-1, Occludin and Claudin-5. Further, the increased levels of TNF-α, IL-1β and IL-6 were confined with Sal administration under the HH condition. Importantly, Sal could downregulate the proteins expression of p-NF-κB-p65, NLRP3, cleaved-Caspase-1 and ASC. Sal also decreased the protein expression of iNOS and COX2 with the increased CD206 and Arg1 expression. Taken together, these data provided that the inhibited NF-κB/NLRP3 pathway by Sal could attenuate HH-induced cerebral oxidative stress injury, inflammatory responses and the blood brain barrier (BBB) damage, attributing to the improved energy metabolism and the microglial phenotype of anti-inflammatory M2. The findings suggested that Sal was expected to be a promising anti-inflammatory agent for high altitude HH-induced brain injury.

Chronic intermittent hypoxia induces the pyroptosis of renal tubular epithelial cells by activating the NLRP3 inflammasome

Obstructive sleep apnea syndrome (OSAS) is a respiratory disorder and chronic intermittent hypoxia (CIH) is an important pathological characteristic of OSAS. Injuries on renal tubular epithelial cells were observed under the condition of CIH. Pyroptosis is a programmed mode of cell death following cell apoptosis and cell necrosis, which is mediated by NLRP3 signaling. The present study aims to investigate the effects of CIH on the pyroptosis of renal tubular epithelial cells and the underlying mechanism. Firstly, CIH was induced in two renal tubular epithelial cell lines, HK-2 cells and TCMK-1 cells. As the aggravation of hypoxia, an increasing trend of elevated apoptotic rate was observed in HK-2 cells and TCMK-1 cells, accompanied by the excessive release of ROS and LDH, and upregulation of NLRP3. Subsequently, the CIH model was established on rats. The pathological analysis results indicated that in CIH rats, the glomerular bottom membrane and mesangium were slightly thickened and edema was observed in the renal tubule epithelium. More serious injury was observed in the moderate intermittent hypoxia group. The expression level of IL-1β and IL-18 was promoted as the aggravation of hypoxia, accompanied by the elevated production of LDH and ROS. The expression level of cleaved Caspase-1, Caspase-1, GSDMD, TLR4, MyD88, NF-κB, p-NF-κB, and NLRP3 was found significantly upregulated as the aggravation of hypoxia. Lastly, the pathological changes in rats induced by CIH were dramatically abolished by MCC950, a specific inhibitor of NLRP3. Collectively, CIH triggered the pyroptosis of renal tubular epithelial cells by activating the NLRP3 inflammasome.

Severe Intermittent Hypoxia Modulates the Macrophage Phenotype and Impairs Wound Healing Through Downregulation of HIF-2α

BACKGROUND

Obstructive sleep apnea is prevalent in patients with diabetic foot ulcers, while the effect of intermittent hypoxia on wound healing is unclear. The objective of this study was to investigate the effect of severe intermittent hypoxia on wound healing.

METHODS

C57BL/6 mice were exposed to 5 weeks of severe intermittent hypoxia or normoxia. The wound healing rate were assessed. The gene expression of CD206 and HIF-2α was tested in vivo and in vitro. Inflammatory factors in RAW264.7 macrophages were measured to investigate the effect of intermittent hypoxia on macrophage polarization. The proliferation of HUVECs and HaCaT cells was also assessed after exposure to intermittent hypoxia.

RESULTS

Severe intermittent hypoxia decreased wound healing at day 3. The expression of CD206 and HIF-2α was significantly decreased after exposure to severe intermittent hypoxia. In vitro, severe intermittent hypoxia significantly promoted M1 phenotype polarization of RAW264.7 macrophages and increased the expression of proinflammatory factors (IL-1β and TNF-α). Severe intermittent hypoxia also decreased the proliferation of HUVECs cultured in endothelial cell medium and HaCaT cells cultured in high glucose DMEM.

CONCLUSION

Severe intermittent hypoxia could lead to M1 but not M2 macrophage polarization through downregulation of HIF-2α, and then lead to impaired wound healing.

Disrupting CISD2 function in cancer cells primarily impacts mitochondrial labile iron levels and triggers TXNIP expression

The CISD2 (NAF-1) protein plays a key role in regulating cellular homeostasis, aging, cancer and neurodegenerative diseases. It was found to control different calcium, reactive oxygen species (ROS), and iron signaling mechanisms. However, since most studies of CISD2 to date were conducted with cells that constitutively lack, overexpress, or contain mutations in CISD2, the relationships between these different signaling processes are unclear. To address the hierarchy of signaling events occurring in cells upon CISD2 disruption, we developed an inducible system to express CISD2, or the dominant-negative H114C inhibitor of CISD2, in human breast cancer cells. Here, we report that inducible disruption of CISD2 function causes an immediate disruption in mitochondrial labile iron (mLI), and that this disruption results in enhanced mitochondrial ROS (mROS) levels. We further show that alterations in cytosolic and ER calcium levels occur only after the changes in mLI and mROS levels happen and are unrelated to them. Interestingly, disrupting CISD2 function resulted in the enhanced expression of the tumor suppressor thioredoxin-interacting protein (TXNIP) that was dependent on the accumulation of mLI and associated with ferroptosis activation. CISD2 could therefore regulate the expression of TXNIP in cancer cells, and this regulation is dependent on alterations in mLI levels.

The involvement of DRP1-mediated caspase-1 activation in inflammatory response by urban particulate matter in EA.hy926 human vascular endothelial cells

Atmospheric particulate matter (PM) has been reported to be closely related to cardiovascular adverse events. However, the underlying mode of action remains to be elucidated. Previous studies have documented that PM induces mitochondrial damage and inflammation, the relation between these two biological outcomes is still unclear though. In this study, we used EA.hy926 human vascular endothelial cells and a standard PM, PM SRM1648a to study the potential effects of mitochondrial dysfunction on endothelial inflammatory responses. As a result, PM SRM1648a changes mitochondrial morphology and interrupts mitochondrial dynamics with a persistent tendency of fission in a dose-dependent manner. Additionally, the caspase-1/IL-1β axis is involved in inflammatory responses but not cell pyroptosis in EA.hy926 cells following the exposure to PM SRM1648a. The activation of caspase-1 has implications in inflammation but not pyroptosis, because caspase-1-dependent pyroptosis is not the main modality of cell death in PM SRM1648a-treated EA.hy926 cells. With regard to the association between mitochondrial damage and inflammation in the case of particle stimulation, DRP1-mediated mitochondrial fission is responsible for inflammatory responses as a result of caspase-1 activation. The current study showed that PM SRM1648a has the ability to disturb mitochondrial dynamics, and trigger endothelial inflammation via DRP1/caspase-1/IL-1β regulatory pathway. In a conclusion, mitochondrial fission enables EA.hy926 cells to facilitate caspase-1 activation in response to PM SRM1648a, which is a crucial step for inflammatory reaction in vascular endothelial cells.

Cell-Selective Altered Cargo Properties of Extracellular Vesicles Following In Vitro Exposures to Intermittent Hypoxia

Intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with cardiovascular and metabolic dysfunction. However, the mechanisms underlying these morbidities remain poorly delineated. Extracellular vesicles (EVs) mediate intercellular communications, play pivotal roles in a multitude of physiological and pathological processes, and could mediate IH-induced cellular effects. Here, the effects of IH on human primary cells and the release of EVs were examined. Microvascular endothelial cells (HMVEC-d), THP1 monocytes, THP1 macrophages M0, THP1 macrophages M1, THP1 macrophages M2, pre-adipocytes, and differentiated adipocytes (HAd) were exposed to either room air (RA) or IH for 24 h. Secreted EVs were isolated and characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. The effects of each of the cell-derived EVs on endothelial cell (EC) monolayer barrier integrity, on naïve THP1 macrophage polarity, and on adipocyte insulin sensitivity were also evaluated. IH did not alter EVs cell quantal release, but IH-EVs derived from HMVEC-d (p < 0.01), THP1 M0 (p < 0.01) and HAd (p < 0.05) significantly disrupted HMVEC-d monolayer integrity, particularly after H₂O₂ pre-conditioning. IH-EVs from HMVEC-d and THP1 M0 elicited M2-polarity changes did not alter insulin sensitivity responses. IH induces cell-selective changes in EVs cargo, which primarily seem to target the emergence of endothelial dysfunction. Thus, changes in EVs cargo from selected cell sources in vivo may play causal roles in some of the adverse outcomes associated with OSA.

Metabolomics Analysis on Obesity-Related Obstructive Sleep Apnea After Weight Loss Management: A Preliminary Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) surgery is an effective type of weight loss management and may improve obesity-related obstructive sleep apnea (OSA). Obese subjects who meet the criteria for surgery with OSA were enrolled. We investigated the metabolomic effects of RYGB on OSA.

METHODS

Clinical data, serum measurements including indices of glycolipid metabolism, and polysomnography (PSG) measurements were collected at baseline and 6 months after RYGB surgery. Metabolomic analysis was performed using ultra-performance liquid chromatography-mass spectrometry.

RESULTS

A group of 37 patients with obesity, type 2 diabetes (T2DM) and suspected OSA were enrolled of which 27 were OSA subjects. After RYGB surgery, metabolic outcomes and sleep parameters were all significantly improved. The OSA remission group had lower valine, isoleucine, and C24:1(cis-15) levels, and higher trimethylamine N-oxide, hippurate, and indole-3-propionic acid levels after RYGB surgery. A combination of preoperative indices (age, apnea-hypopnea index (AHI), fasting C-peptide level, and hippurate level) predicted the RYGB effect size in obese patients with T2DM and OSA, with an area under receiver operating characteristic curve of 0.947, specificity of 82.4%, and sensitivity of 100%.

CONCLUSIONS

RYGB surgery may significantly improve the metabolic status of patients with obesity, T2DM and OSA. A combination of preoperative indices (age, AHI, fasting C peptide level, and hippurate level) may be useful for predicting the effect size of RYGB in obese patients with T2DM and OSA. The mechanisms underlying OSA remission need to be explored.