Immune consequences of exercise in hypoxia:A narrative review

Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type,dose(frequency/duration,intensity),and individual characteristics.Similarly,reduced availability of ambient oxygen(hypoxia)modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia.How combined exercise and hypoxia(e.g.,high-altitude training)sculpts immune responses is not well understood,although such combinations are becoming increasingly popular.Therefore,in this paper,we summarize the impact on immune responses of exercise and of hypoxia,both independently and together,with a focus on specialized cells in the innate and adaptive immune system.We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia,then we discuss how they may be modulated by nutritional strategies.Mitochondrial,antioxidant,and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism,resilience,and overall immune functions by regulating the survival,differentiation,activation,and migration of immune cells.This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions.Appropriate acclimatization,training,and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.

Hypoxia-mediated programmed cell death is involved in the formation of wooden breast in broilers

Background Wooden breast(WB)myopathy is a common myopathy found in commercial broiler chickens worldwide.Histological examination has revealed that WB myopathy is accompanied by damage to the pectoralis major(PM)muscle.However,the underlying mechanisms responsible for the formation of WB in broilers have not been fully elucidated.This study aimed to investigate the potential role of hypoxia-mediated programmed cell death(PCD)in the formation of WB myopathy.Results Histological examination and biochemical analysis were performed on the PM muscle of the control(CON)and WB groups.A significantly increased thickness of the breast muscle in the top,middle,and bottom portions(P<0.01)was found along with pathological structure damage of myofibers in the WB group.The number of capillaries per fiber in PM muscle,and the levels of p O_(2) and s O_(2) in the blood,were significantly decreased(P<0.01),while the levels of p CO_(2) and TCO_(2) in the blood were significantly increased(P<0.05),suggesting hypoxic conditions in the PM muscle of the WB group.We further evaluated the PCD-related pathways including autophagy,apoptosis,and necroptosis to understand the consequence response to enhanced hypoxic conditions in the PM muscle of birds with WB.The ratio of LC3 II to LC3 I,and the autophagy-related factors HIF-1α,BNIP3,Beclin1,AMPKα,and ULK1 at the m RNA and protein levels,were all significantly upregulated(P<0.05),showing that autophagy occurred in the PM muscle of the WB group.The apoptotic index,as well as the expressions of Bax,Cytc,caspase 9,and caspase 3,were significantly increased(P<0.05),whereas Bcl-2 was significantly decreased(P<0.05)in the WB-affected PM muscle,indicating the occurrence of apoptosis mediated by the mitochondrial pathway.Additionally,the expressions of necroptosis-related factors RIP1,RIP3,and MLKL,as well as NF-κB and the pro-inflammatory cytokines TNF-α,IL-1β,and IL-6,were all significantly enhanced(P<0.05)in the WB-affected PM muscle.Conclusions The WB myopathy reduces blood supply and induces hypoxia in the PM muscle,which is closely related to the occurrence of PCD including apoptosis,autophagy,and necroptosis within myofibers,and finally leads to abnormal muscle damage and the development of WB in broilers.

Effect of tubastatin A on NLRP3 inflammasome activation in macrophages under hypoxia/ reoxygenation conditions

BACKGROUND:There are currently no effective drugs to mitigate the ischemia/reperfusion injury caused by fluid resuscitation after hemorrhagic shock(HS).The aim of this study was to explore the potential of the histone deacetylase 6(HDAC6)-specific inhibitor tubastatin A(TubA)to suppress nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome activation in macrophages under hypoxia/reoxygenation(H/R)conditions.METHODS:The viability of RAW264.7 cells subjected to H/R after treatment with different concentrations of TubA was assessed using a cell-counting kit-8(CCK8)assay.Briefly,2.5μmol/L TubA was used with RAW264.7 cells under H/R condition.RAW264.7 cells were divided into three groups,namely the control,H/R,and TubA groups.The levels of reactive oxygen species(ROS)in the cells were detected using fluorescence microscopy.The protein expression of HDAC6,heat shock protein 90(Hsp90),inducible nitric oxide synthase(iNOS),NLRP3,gasdermin-D(GSDMD),Caspase-1,GSDMD-N,and Caspase-1 p20 was detected by western blotting.The levels of interleukin-1β(IL-1β)and IL-18 in the supernatants were detected using enzyme-linked immunosorbent assay(ELISA).RESULTS:HDAC6,Hsp90,and iNOS expression levels were significantly higher(P<0.01)in the H/R group than in the control group,but lower in the TubA group than in the H/R group(P<0.05).When comparing the H/R group to the control group,ROS levels were significantly higher(P<0.01),but significantly reduced in the TubA group(P<0.05).The H/R group had higher NLRP3,GSDMD,Caspase-1,GSDMD-N,and Caspase-1 p20 expression levels than the control group(P<0.05),however,the TubA group had significantly lower expression levels than the H/R group(P<0.05).IL-1βand IL-18 levels in the supernatants were significantly higher in the H/R group compared to the control group(P<0.01),but significantly lower in the TubA group compared to the H/R group(P<0.01).CONCLUSION:TubA inhibited the expression of HDAC6,Hsp90,and iNOS in macrophages subjected to H/R.This inhibition led to a decrease in the content of ROS in cells,which subsequently inhibited the activation of the NLRP3 inflammasome and the secretion of IL-1βand IL-18.

Molecular mechanism of hypoxia and alpha-ketoglutaric acid on collagen expression in scleral fibroblasts

AIM:To investigate the molecular mechanisms underlying the influence of hypoxia and alpha-ketoglutaric acid(α-KG)on scleral collagen expression.METHODS:Meta-analysis and clinical statistics were used to prove the changes in choroidal thickness(ChT)during myopia.The establishment of a hypoxic myopia model(HYP)for rabbit scleral fibroblasts through hypoxic culture and the effects of hypoxia andα-KG on collagen expression were demonstrated by Sirius red staining.Transcriptome analysis was used to verify the genes and pathways that hypoxia andα-KG affect collagen expression.Finally,real-time quantitative reverse transcription polymerase chain reaction(RT-qPCR)was used for reverse verification.RESULTS:Meta-analysis results aligned with clinical statistics,revealing a thinning of ChT,leading to scleral hypoxia.Sirius red staining indicated lower collagen expression in the HYP group and higher collagen expression in the HYP+α-KG group,showed that hypoxia reduced collagen expression in scleral fibroblasts,whileα-KG can elevated collagen expression under HYP conditions.Transcriptome analysis unveiled the related genes and signaling pathways of hypoxia andα-KG affect scleral collagen expression and the results were verified by RT-qPCR.CONCLUSION:The potential molecular mechanisms through which hypoxia andα-KG influencing myopia is unraveled and three novel genes TLCD4,TBC1D4,and EPHX3 are identified.These findings provide a new perspective on the prevention and treatment of myopia via regulating collagen expression.

CA IX-targeted Ag_(2)S quantum dots bioprobe for NIR-II imaging-guided hypoxia tumor chemo-photothermal therapy

Hypoxia is the common characteristic of almost all solid tumors,which prevents therapeutic drugs from reaching the tumors.Therefore,the development of new targeted agents for the accurate diagnosis of hypoxia tumors is widely concerned.As carbonic anhydrase IX(CA IX)is abundantly distributed on the hypoxia tumor cells,it is considered as a potential tumor biomarker.4-(2-Aminoethyl)benzenesulfonamide(ABS)as a CA IX inhibitor has inherent inhibitory activity and good targeting effect.In this study,Ag_(2)S quantum dots(QDs)were used as the carrier to prepare a novel diagnostic and therapeutic bioprobe(Ag_(2)S@polyethylene glycol(PEG)-ABS)through ligand exchange and amide condensation reaction.Ag_(2)S@PEG-ABS can selectively target tumors by surface-modified ABS and achieve accurate tumor imaging by the near infrared-II(NIR-II)fluorescence characteristics of Ag_(2)S QDs.PEG modification of Ag_(2)S QDs greatly improves its water solubility and stability,and therefore achieves high photothermal stability and high photothermal conversion efficiency(PCE)of 45.17%.Under laser irradiation,Ag_(2)S@PEG-ABS has powerful photothermal and inherent antitumor combinations on colon cancer cells(CT-26)in vitro.It also has been proved that Ag_(2)S@PEG-ABS can realize the effective treatment of hypoxia tumors in vivo and show good biocompatibility.Therefore,it is a new efficient integrated platform for the diagnosis and treatment of hypoxia tumors.

Coastal hypoxia response to the coupling of catastrophic flood,extreme marine heatwave and typhoon:a case study off the Changjiang River Estuary in summer 2020

Massive bodies of low-oxygen bottom waters are found in coastal areas worldwide,which are detrimental to coastal ecosystems.In summer 2020,the response of coastal hypoxia to extreme weather events,including a catastrophic flooding,an extreme marine heatwave,and Typhoon Bavi,is investigated based on multiple satellite,four cruises,and mooring observations.The extensive fan-shaped hypoxia zone presents significant northward extension during July-September 2020,and is estimated as large as 13 000 km^(2) with rather low oxygen minimum(0.42 mg/L) during its peak in 28-30 August.This severe hypoxia is attributed to the persistent strong stratification,which is indicated by flood-induced larger amount of riverine freshwater input and subsequent marine heatwave off the Changjiang River Estuary.Moreover,the Typhoon Bavi has limited effect on the marine heatwave and coastal hypoxia in summer 2020.

CircPMS1 promotes proliferation of pulmonary artery smooth muscle cells,pulmonary microvascular endothelial cells,and pericytes under hypoxia

Background:Circular RNAs(circRNAs)have been recognized as significant regulators of pulmonary hypertension(PH);however,the differential expression and function of circRNAs in different vascular cells under hypoxia remain unknown.Here,we identified co-differentially expressed circRNAs and determined their putative roles in the proliferation of pulmonary artery smooth muscle cells(PASMCs),pulmonary microvascular endothelial cells(PMECs),and pericytes(PCs)under hypoxia.Methods:Whole transcriptome sequencing was performed to analyze the differential expression of circRNAs in three different vascular cell types.Bioinformatic analysis was used to predict their putative biological function.Quantitative real-time polymerase chain reaction,Cell Counting Kit-8,and EdU Cell Proliferation assays were carried out to determine the role of circular postmeiotic segregation 1(circPMS1)as well as its potential sponge mechanism in PASMCs,PMECs,and PCs.Results:PASMCs,PMECs,and PCs exhibited 16,99,and 31 differentially expressed circRNAs under hypoxia,respectively.CircPMS1 was upregulated in PASMCs,PMECs,and PCs under hypoxia and enhanced the proliferation of vascular cells.CircPMS1may upregulate DEP domain containing 1(DEPDC1)and RNA polymerase II subunit D expression by targeting microRNA-432-5p(miR-432-5p)in PASMCs,upregulate MAX interactor 1(MXI1)expression by targeting miR-433-3p in PMECs,and upregulate zinc finger AN1-type containing 5(ZFAND5)expression by targeting miR-3613-5p in PCs.Conclusions:Our results suggest that circPMS1 promotes cell proliferation through the miR-432-5p/DEPDC1 or miR-432-5p/POL2D axis in PASMCs,through the miR-433-3p/MXI1 axis in PMECs,and through the miR-3613-5p/ZFAND5 axis in PCs,which provides putative targets for the early diagnosis and treatment of PH.

Effects of high glucose and severe hypoxia on the biological behavior of mesenchymal stem cells at various passages

BACKGROUND Mesenchymal stem cells(MSCs)have been extensively studied for therapeutic potential,due to their regenerative and immunomodulatory properties.Serial passage and stress factors may affect the biological characteristics of MSCs,but the details of these effects have not been recognized yet.AIM To investigate the effects of stress factors(high glucose and severe hypoxia)on the biological characteristics of MSCs at different passages,in order to optimize the therapeutic applications of MSCs.METHODS In this study,we investigated the impact of two stress conditions;severe hypoxia and high glucose on human adipose-tissue derived MSCs(hAD-MSCs)at passages 6(P6),P8,and P10.Proliferation,senescence and apoptosis were evaluated measuring WST-1,senescence-associated beta-galactosidase,and annexin V,respectively.RESULTS Cells at P6 showed decreased proliferation and increased apoptosis under conditions of high glucose and hypoxia compared to control,while the extent of senescence did not change significantly under stress conditions.At P8 hAD-MSCs cultured in stress conditions had a significant decrease in proliferation and apoptosis and a significant increase in senescence compared to counterpart cells at P6.Cells cultured in high glucose at P10 had lower proliferation and higher senescence than their counterparts in the previous passage,while no change in apoptosis was observed.On the other hand,MSCs cultured under hypoxia showed decreased senescence,increased apoptosis and no significant change in proliferation when compared to the same conditions at P8.CONCLUSION These results indicate that stress factors had distinct effects on the biological processes of MSCs at different passages,and suggest that senescence may be a protective mechanism for MSCs to survive under stress conditions at higher passage numbers.

Acidic/hypoxia dual-alleviated nanoregulators for enhanced treatment of tumor chemo-immunotherapy

Chemotherapy plays a crucial role in triple-negative breast cancer (TNBC) treatment as it not only directly kills cancer cells but also induces immunogenic cell death. However, the chemotherapeutic efficacy was strongly restricted by the acidic and hypoxic tumor environment. Herein, we have successfully formulated PLGA-based nanoparticles concurrently loaded with doxorubicin (DOX), hemoglobin (Hb) and CaCO3 by a CaCO3-assisted emulsion method, aiming at the effective treatment of TNBC. We found that the obtained nanomedicine (DHCaNPs) exhibited effective drug encapsulation and pH-responsive drug release behavior. Moreover, DHCaNPs demonstrated robust capabilities in neutralizing protons and oxygen transport. Consequently, DHCaNPs could not only serve as oxygen nanoshuttles to attenuate tumor hypoxia but also neutralize the acidic tumor microenvironment (TME) by depleting lactic acid, thereby effectively overcoming the resistance to chemotherapy. Furthermore, DHCaNPs demonstrated a notable ability to enhance antitumor immune responses by increasing the frequency of tumor-infiltrating effector lymphocytes and reducing the frequency of various immune-suppressive cells, therefore exhibiting a superior efficacy in suppressing tumor growth and metastasis when combined with anti-PD-L1 (αPD-L1) immunotherapy. In summary, this study highlights that DHCaNPs could effectively attenuate the acidic and hypoxic TME, offering a promising strategy to figure out an enhanced chemo-immunotherapy to benefit TNBC patients.

Hypoxia-inducible factor-1αin myocardial infarction

Hypoxia-inducible factor 1(HIF1)has a crucial function in the regulation of oxygen levels in mammalian cells,especially under hypoxic conditions.Its importance in cardiovascular diseases,particularly in cardiac ischemia,is because of its ability to alleviate cardiac dysfunction.The oxygen-responsive subunit,HIF1α,plays a crucial role in this process,as it has been shown to have cardioprotective effects in myocardial infarction through regulating the expression of genes affecting cellular survival,angiogenesis,and metabolism.Furthermore,HIF1αexpression induced reperfusion in the ischemic skeletal muscle,and hypoxic skin wounds in diabetic animal models showed reduced HIF1αexpression.Increased expression of HIF1αhas been shown to reduce apoptosis and oxidative stress in cardiomyocytes during acute myocardial infarction.Genetic variations in HIF1αhave also been found to correlate with altered responses to ischemic cardiovascular disease.In addition,a link has been established between the circadian rhythm and hypoxic molecular signaling pathways,with HIF1αfunctioning as an oxygen sensor and circadian genes such as period circadian regulator 2 responding to changes in light.This editorial analyzes the relationship between HIF1αand the circadian rhythm and highlights its significance in myocardial adaptation to hypoxia.Understanding the changes in molecular signaling pathways associated with diseases,specifically cardiovascular diseases,provides the opportunity for innovative therapeutic interventions,especially in low-oxygen environments such as myocardial infarction.

Effect of exercise during pregnancy on offspring development through ameliorating high glucose and hypoxia in gestational diabetes mellitus

BACKGROUND Gestational diabetes mellitus(GDM)women require prenatal care to minimize short-and long-term complications.The mechanism by which exercise during pregnancy affects organ development and whether glucose transporter(GLUT)1 plays a role in GDM offspring organ development remains unknown.AIM To determine the effect of exercise during pregnancy on the cardiac,hepatic and renal development of GDM mother’s offspring.METHODS Placenta samples were collected from humans and mice.GDM mouse models were created using streptozotocin along with a GDM with exercise group.The hearts,livers and kidneys of 3-and 8-week-old offspring were collected for body composition analysis and staining.The effects of high glucose levels and hypoxia were investigated using HTR8/SVneo.Transwell and wound-healing assays were performed to assess cell migration.Immunofluorescence accompanied with TUNEL and Ki67 staining was used to explore apoptosis and proliferation.RESULTS Exercise during pregnancy downregulated the GLUT1 and hypoxia inducible factor-1αexpression in placenta from individuals with GDM.Cobalt chloride induced hypoxia and high glucose levels also significantly decreased migration and apoptosis of HTR8/SVneo cells.In addition,exercise reduced inflammatory cell infiltration in the liver and decreased the tubular vacuolar area in the kidneys of offspring.CONCLUSION GDM affects the growth and development of organs in offspring.Exercise during pregnancy can reverse adverse effects of GDM on the development of the heart,liver,and kidney in offspring.

Nicotinamide adenine dinucleotide treatment confers resistance to neonatal ischemia and hypoxia:effects on neurobehavioral phenotypes

Neonatal hypoxic-ischemic brain injury is the main cause of hypoxic-ischemic encephalopathy and cerebral palsy.Currently,there are few effective clinical treatments for neonatal hypoxic-ischemic brain injury.Here,we investigated the neuroprotective and molecular mechanisms of exogenous nicotinamide adenine dinucleotide,which can protect against hypoxic injury in adulthood,in a mouse model of neonatal hypoxic-ischemic brain injury.In this study,nicotinamide adenine dinucleotide(5 mg/kg)was intraperitoneally administered 30 minutes befo re surgery and every 24 hours thereafter.The results showed that nicotinamide adenine dinucleotide treatment improved body weight,brain structure,adenosine triphosphate levels,oxidative damage,neurobehavioral test outcomes,and seizure threshold in experimental mice.Tandem mass tag proteomics revealed that numerous proteins were altered after nicotinamide adenine dinucleotide treatment in hypoxic-ischemic brain injury mice.Parallel reaction monitoring and western blotting confirmed changes in the expression levels of proteins including serine(or cysteine)peptidase inhibitor,clade A,member 3N,fibronectin 1,5'-nucleotidase,cytosolic IA,microtubule associated protein 2,and complexin 2.Proteomics analyses showed that nicotinamide adenine dinucleotide ameliorated hypoxic-ischemic injury through inflammation-related signaling pathways(e.g.,nuclear factor-kappa B,mitogen-activated protein kinase,and phosphatidylinositol 3 kinase/protein kinase B).These findings suggest that nicotinamide adenine dinucleotide treatment can improve neurobehavioral phenotypes in hypoxic-ischemic brain injury mice through inflammation-related pathways.

Small extracellular vesicles from hypoxia-preconditioned bone marrow mesenchymal stem cells attenuate spinal cord injury via miR-146a-5p-mediated regulation of macrophage polarization

Spinal cord injury is a disabling condition with limited treatment options.Multiple studies have provided evidence suggesting that small extracellular vesicles(SEVs)secreted by bone marrow mesenchymal stem cells(MSCs)help mediate the beneficial effects conferred by MSC transplantation following spinal cord injury.Strikingly,hypoxia-preconditioned bone marrow mesenchymal stem cell-derived SEVs(HSEVs)exhibit increased therapeutic potency.We thus explored the role of HSEVs in macrophage immune regulation after spinal cord injury in rats and their significance in spinal cord repair.SEVs or HSEVs were isolated from bone marrow MSC supernatants by density gradient ultracentrifugation.HSEV administration to rats via tail vein injection after spinal cord injury reduced the lesion area and attenuated spinal cord inflammation.HSEVs regulate macrophage polarization towards the M2 phenotype in vivo and in vitro.Micro RNA sequencing and bioinformatics analyses of SEVs and HSEVs revealed that mi R-146a-5p is a potent mediator of macrophage polarization that targets interleukin-1 receptor-associated kinase 1.Reducing mi R-146a-5p expression in HSEVs partially attenuated macrophage polarization.Our data suggest that HSEVs attenuate spinal cord inflammation and injury in rats by transporting mi R-146a-5p,which alters macrophage polarization.This study provides new insights into the application of HSEVs as a therapeutic tool for spinal cord injury.

Novel Role of Calcium-Sensitive Receptors in Chronic Hypoxia-Induced Proliferation of Pulmonary Vein Smooth Muscle Cells

Objective:Vascular remodeling due to chronic hypoxia(CH)occurs not only in the pulmonary arteries but also in the pulmonary veins.Pulmonary vascular remodeling arises from the proliferation of pulmonary vascular myocytes.However,the mechanism by which CH induces the proliferation of pulmonary vein smooth muscle cells(PVSMCs)is unknown.This study aimed to investigate the mechanism by which CH affects the proliferation of PVSMCs.Methods:PVSMCs were isolated from rat distal pulmonary veins and exposed to CH(4%O2,60h),and the expression of the calcium-sensitive receptor(CaSR)was detected by Western blotting and immunofluorescence.MTT assay was used to detect the proliferation viability of the cells,and the changes in the intracellular calcium concentration were detected by laser confocal scanning technique.Results:CaSR expression was present in rat distal PVSMCs,and CaSR protein expression was upregulated under hypoxia.The positive regulator spermine not only enhanced CH-induced CaSR upregulation but also enhanced CH-induced increase in cell viability and calcium ion concentration.The negative CaSR regulator NPS2143 not only attenuated CH-induced CaSR upregulation but also inhibited CH-induced cell viability and calcium ion concentration.Conclusion:CaSR-mediated hyperproliferation is a novel pathogenic mechanism for the development of proliferation in distal PVSMCs under CH conditions.

Delayed xenon post-conditioning mitigates spinal cord ischemia/reperfusion injury in rabbits by regulating microglial activation and inflammatory factors

The neuroprotective effect against spinal cord ischemia/reperfusion injury in rats exerted by delayed xenon post-conditioning is stronger than that produced by immediate xenon post-conditioning. However, the mechanisms underlying this process remain unclear. Activated microglia are the main inflammatory cell type in the nervous system. The release of pro-inflammatory factors following microglial activation can lead to spinal cord damage, and inhibition of microglial activation can relieve spinal cord ischemia/reperfusion injury. To investigate how xenon regulates microglial activation and the release of inflammatory factors, a rabbit model of spinal cord ischemia/reperfusion injury was induced by balloon occlusion of the infrarenal aorta. After establishment of the model, two interventions were given： （1） immediate xenon post-conditioning—after reperfusion, inhalation of 50% xenon for 1 hour, 50% N2/50%O2 for 2 hours; （2） delayed xenon post-conditioning—after reperfusion, inhalation of 50% N2/50%O2 for 2 hours, 50% xenon for 1 hour. At 4, 8, 24, 48 and 72 hours after reperfusion, hindlimb locomotor function was scored using the Jacobs locomotor scale. At 72 hours after reperfusion, interleukin 6 and interleukin 10 levels in the spinal cord of each group were measured using western blot assays. Iba1 levels were determined using immunohistochemistry and a western blot assay. The number of normal neurons at the injury site was quantified using hematoxylin-eosin staining. At 72 hours after reperfusion, delayed xenon post-conditioning remarkably enhanced hindlimb motor function, increased the number of normal neurons at the injury site, decreased Iba1 levels, and inhibited interleukin-6 and interleukin-10 levels in the spinal cord.Immediate xenon post-conditioning did not noticeably affect the above-mentioned indexes. These findings indicate that delayed xenon post-conditioning after spinal cord injury improves the recovery of neurological function by reducing microglial activation and the release of interleukin-6 and interleukin-10.

Ischemic post-conditioning to counteract intestinal ischemia/reperfusion injury

Intestinal ischemia is a severe disorder with a variety of causes.Reperfusion is a common occurrence during treatment of acute intestinal ischemia but the injury resulting from ischemia/reperfusion(IR)may lead toeven more serious complications from intestinal atrophy to multiple organ failure and death.The susceptibility of the intestine to IR-induced injury(IRI)appears from various experimental studies and clinical settings such as cardiac and major vascular surgery and organ transplantation.Where as oxygen free radicals,activation of leukocytes,failure of microvascular perfusion,cellular acidosis and disturbance of intracellular homeo-stasis have been implicated as important factors inthe pathogenesis of intestinal IRI,the mechanisms underlying this disorder are not well known.To date,increasing attention is being paid in animal studies to potential pre-and post-ischemia treatments that protect against intestinal IRI such as drug interference with IR-induced apoptosis and inflammation processes and ischemic pre-conditioning.However,better insight is needed into the molecular and cellular events associated with reperfusion-induced damage to develop effective clinical protection protocols to combat this disorder.In this respect,the use of ischemic post-conditioning in combination with experimentally prolonged acidosis blocking deleterious reperfusion actions may turn out to have particular clinical relevance.

Oxygen Glucose Deprivation Post-conditioning Protects Cortical Neurons against Oxygen-glucose Deprivation Injury: Role of HSP70 and Inhibition of Apoptosis

In the present study, we examined the effect of oxygen glucose deprivation（OGD） post-conditioning（PostC） on neural cell apoptosis in OGD-PostC model and the protective effect on primary cortical neurons against OGD injury in vitro. Four-h OGD was induced by OGD by using a specialized and humidified chamber. To initiate OGD, culture medium was replaced with de-oxygenated and glucose-free extracellular solution-Locke＇s medium. After OGD treatment for 4 h, cells were then allowed to recover for 6 h or 20 h. Then lactate dehydrogenase（LDH） release assay, Western blotting and flow cytometry were used to detect cell death, protein levels and apoptotic cells, respectively. For the PostC treatment, three cycles of 15-min OGD, followed by 15 min normal cultivation, were applied immediately after injurious 4-h OGD. Cells were then allowed to recover for 6 h or 20 h, and cell death was assessed by LDH release assay. Apoptotic cells were flow cytometrically evaluated after 4-h OGD, followed by re-oxygenation for 20 h（O4/R20）. In addition, Western blotting was used to examine the expression of heat-shock protein 70（HSP70）, Bcl-2 and Bax. The ratio of Bcl-2 expression was（0.44±0.08）% and（0.76±0.10）%, and that of Bax expression was（0.51±0.05）% and（0.39±0.04）%, and that of HSP70 was（0.42±0.031）% and（0.72±0.045）% respectively in OGD group and PostC group. After O4/R6, the rate of neuron death in PostC group and OGD groups was（28.96±3.03）% and（37.02±4.47）%, respectively. Therefore, the PostC treatment could up-regulate the expression of HSP70 and Bcl-2, but down-regulate Bax expression. As compared with OGD group, OGD-induced neuron death and apoptosis were significantly decreased in PostC group（P0.05）. These findings suggest that PostC inhibited OGD-induced neuron death. This neuro-protective effect is likely achieved by anti-apoptotic mechanisms and is associated with over-expression of HSP70.

Stress granules inhibit endoplasmic reticulum stress-mediated apoptosis during hypoxia-induced injury in acute liver failure

BACKGROUND Stress granules(SGs)could be formed under different stimulation to inhibit cell injury.AIM To investigate whether SGs could protect hepatocytes from hypoxia-induced damage during acute liver failure(ALF)by reducing endoplasmic reticulum stress(ERS)mediated apoptosis.METHODS The agonist of SGs,arsenite(Ars)was used to intervene hypoxia-induced hepatocyte injury cellular model and ALF mice models.Further,the siRNA of activating transcription factor 4(ATF4)and SGs inhibitor anisomycin was then used to intervene in cell models.RESULTS With the increase of hypoxia time from 4 h to 12 h,the levels of HIF-1α,ERS and apoptosis gradually increased,and the expression of SGs marker G3BP1 and TIA-1 was increased and then decreased.Compared with the hypoxia cell model group and ALF mice model,the levels of HIF-1α,apoptosis and ERS were increased in the Ars intervention group.After siRNA-ATF4 intervention,the level of SGs in cells increased,and the levels of HIF-1α,ERS and apoptosis decreased.Compared with the siRNA-ATF4 group,the levels of G3BP1 in the siRNAATF4+anisomycin group were decreased,and the levels of HIF-1α,ERS and apoptosis were increased.Moreover,compared with the ALF group,the degree of liver injury and liver function,the levels of HIF-1α,ERS and apoptosis in the Ars intervention group were decreased,the level of SGs was increased.CONCLUSION SGs could protect hepatocytes from hypoxia-induced damage during ALF by reducing ERSmediated apoptosis.

The effect of an adaptation to hypoxia on cardiac tolerance to ischemia/reperfusion

The acute myocardial infarction(AMI)and sudden cardiac death(SCD),both associated with acute cardiac ischemia,are one of the leading causes of adult death in economically developed countries.The development of new approaches for the treatment and prevention of AMI and SCD remains the highest priority for medicine.A study on the cardiovascular effects of chronic hypoxia(CH)may contribute to the development of these methods.Chronic hypoxia exerts both positive and adverse effects.The positive effects are the infarct-reducing,vasoprotective,and antiarrhythmic effects,which can lead to the improvement of cardiac contractility in reperfusion.The adverse effects are pulmonary hypertension and right ventricular hypertrophy.This review presents a comprehensive overview of how CH enhances cardiac tolerance to ischemia/reperfusion.It is an in-depth analysis of the published data on the underlying mechanisms,which can lead to future development of the cardioprotective effect of CH.A better understanding of the CH-activated protective signaling pathways may contribute to new therapeutic approaches in an increase of cardiac tolerance to ischemia/reperfusion.

DI-3-n-butylphthalide exerts neuroprotective effects by modulating hypoxia-inducible factor 1-alpha ubiquitination to attenuate oxidative stress-induced apoptosis

DI-3-n-butylphthalide is used to treat mild and moderate acute ischemic stroke.However,the precise underlying mechanism requires further investigation.In this study,we investigated the molecular mechanism of DI-3-n-butylphthalide action by various means.We used hydrogen peroxide to induce injury to PC12cells and RAW264.7 cells to mimic neuronal oxidative stress injury in stroke in vitro and examined the effects of DI-3-n-butylphthalide.We found that DI-3-nbutylphthalide pretreatment markedly inhibited the reduction in viability and reactive oxygen species production in PC12 cells caused by hydrogen peroxide and inhibited cell apoptosis.Furthermore,DI-3-n-butylphthalide pretreatment inhibited the expression of the pro-apoptotic genes Bax and Bnip3.DI-3-nbutylphthalide also promoted ubiquitination and degradation of hypoxia inducible factor 1α,the key transcription factor that regulates Bax and Bnip3 genes.These findings suggest that DI-3-n-butylphthalide exhibits a neuroprotective effect on stroke by promoting hypoxia inducible factor-1α ubiquitination and degradation and inhibiting cell apoptosis.