Hypoxia-induced Reactive Oxygen Species Research Articles

Hypoxia-induced cysteine metabolism reprogramming is crucial for the tumorigenesis of colorectal cancer

Metabolic reprogramming is a hallmark of human cancer, and cancer-specific metabolism provides opportunities for cancer diagnosis, prognosis, and treatment. However, the underlying mechanisms by which metabolic pathways affect the initiation and progression of colorectal cancer (CRC) remain largely unknown. Here, we demonstrate that cysteine is highly enriched in colorectal tumors compared to adjacent non-tumor tissues, thereby promoting tumorigenesis of CRC. Synchronously importing both cysteine and cystine in colorectal cancer cells is necessary to maintain intracellular cysteine levels. Hypoxia-induced reactive oxygen species (ROS) and ER stress regulate the co-upregulation of genes encoding cystine transporters (SLC7A11, SLC3A2) and genes encoding cysteine transporters (SLC1A4, SLC1A5) through the transcription factor ATF4. Furthermore, the metabolic flux from cysteine to reduced glutathione (GSH), which is critical to support CRC growth, is increased due to overexpression of glutathione synthetase GSS in CRC. Depletion of cystine/cysteine by recombinant cyst(e)inase effectively inhibits the growth of colorectal tumors by inducing autophagy in colorectal cancer cells through mTOR-ULK signaling axis. This study demonstrates the underlying mechanisms of cysteine metabolism in tumorigenesis of CRC, and evaluates the potential of cysteine metabolism as a biomarker or a therapeutic target for CRC.

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

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

The calcium-dependent protein kinase CPK16 regulates hypoxia-induced ROS production by phosphorylating the NADPH oxidase RBOHD in Arabidopsis.

Reactive oxygen species (ROS) production is a key event in modulating plant responses to hypoxia and post-hypoxia reoxygenation. However, the molecular mechanism by which hypoxia-associated ROS homeostasis is controlled remains largely unknown. Here, we showed that the calcium-dependent protein kinase CPK16 regulates plant hypoxia tolerance by phosphorylating the plasma membrane-anchored NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) to regulate ROS production in Arabidopsis (Arabidopsis thaliana). In response to hypoxia or reoxygenation, CPK16 was activated through phosphorylation of its Ser274 residue. The cpk16 knockout mutant displayed enhanced hypoxia tolerance, whereas CPK16-overexpressing (CPK16-OE) lines showed increased sensitivity to hypoxic stress. In agreement with these observations, hypoxia and reoxygenation both induced ROS accumulation in the rosettes of CPK16-OEs more strongly than in rosettes of the cpk16-1 mutant or the wild type. Moreover, CPK16 interacted with and phosphorylated the N terminus of RBOHD at four serine residues (Ser133, Ser148, Ser163, and Ser347) that were necessary for hypoxia- and reoxygenation-induced ROS accumulation. Furthermore, the hypoxia-tolerant phenotype of cpk16-1 was fully abolished in the cpk16 rbohd double mutant. Thus, we have uncovered a regulatory mechanism by which the CPK16-RBOHD module shapes ROS production during hypoxia and reoxygenation in Arabidopsis.

Chemical Hypoxia Induces Pyroptosis in Neuronal Cells by Caspase-Dependent Gasdermin Activation.

Hypoxia-induced neuronal death is a major cause of neurodegenerative diseases. Pyroptosis is a type of inflammatory programmed cell death mediated by elevated intracellular levels of reactive oxygen species (ROS). Therefore, we hypothesized that hypoxia-induced ROS may trigger pyroptosis via caspase-dependent gasdermin (GSDM) activation in neuronal cells. To test this, we exposed SH-SY5Y neuronal cells to cobalt chloride (CoCl2) to trigger hypoxia and then evaluated the cellular and molecular responses to hypoxic conditions. Our data revealed that CoCl2 induced cell growth inhibition and the expression of hypoxia-inducible factor-1α in SH-SY5Y cells. Exposure to CoCl2 elicits excessive accumulation of cytosolic and mitochondrial ROS in SH-SY5Y cells. CoCl2-induced hypoxia not only activated the intrinsic (caspases-3, -7, and -9) apoptotic pathway but also induced caspase-3/GSDME-dependent and NLRP3/caspase-1/GSDMD-mediated pyroptosis in SH-SY5Y cells. Importantly, inhibition of caspase-3 and -1 using selective inhibitors ameliorated pyroptotic cell death and downregulated GSDM protein expression. Additionally, treatment with a ROS scavenger significantly suppressed caspase- and pyroptosis-related proteins in CoCl2-treated SH-SY5Y cells. Our findings indicate that hypoxia-mediated ROS production plays an important role in the activation of both apoptosis and pyroptosis in SH-SY5Y neuronal cells, thus providing a potential therapeutic strategy for hypoxia-related neurological diseases.

Retinoic acid-related orphan receptors regulate autophagy and cell survival in cardiac myocytes during hypoxic stress

Introduction: Autophagy is a highly conserved evolutionary process that regulates cell quality control through protein degradation, organelle turnover, and recycling of cellular components by fusing with lysosomes. Defects in autophagy can lead to increased reactive oxygen species (ROS) and oxidative stress from impaired mitochondrial clearance by mitophagy. These defects are commonly associated with chronic human diseases such as cancer, myocardial infarction, neurodegenerative diseases, and aging. Aim: Herein, we show that the gene Retinoic Acid-Related Orphan Receptors α (Rora ) is cardioprotective through modulation of autophagy and clearance of damaged ROS-producing mitochondria in cardiac myocytes. Methods and results: We show that RORα is downregulated during hypoxia, leading to increased death of cardiac cells and enhanced mitochondrial perturbations. We demonstrate that the small molecule Nobiletin, a polymethoxy flavonoid, can induce RORα activation and downregulate the aging-associated marker p16, coincident with reduced ROS-producing mitochondria. We further show that Nobiletin binds directly to the Rora gene promoter, leading to activation of autophagic function and increased cell survival of cardiac myocytes during hypoxia. Interestingly, loss of RORα activity during hypoxia resulted in the failure of Nobiletin to rescue autophagy and inhibits its capacity for cardiac protection. Furthermore, the inactivation of autophagy by ATG7 knockdown abrogated the cytoprotective effects of Nobiletin on autophagic activation. Conclusion: Collectively, these results demonstrate that RORα regulates autophagic processes linked to aging upon activation with Nobiletin. Interventions that activate RORα may prove beneficial in reducing hypoxia-induced mitochondrial ROS associated with cardiac aging.

H2O2 transit through the mitochondrial intermembrane space promotes tumor cell growth in vitro and in vivo

Cancer cells experience increased levels of oxidant stress as a consequence of oncogene activation, nucleotide biosynthesis, and growth factor receptor signaling. Mitochondria contribute to this redox stress by generating reactive oxygen species (ROS) along the electron transport chain, which are released to the matrix and the intermembrane space (IMS). Assessing the contribution of mitochondrial ROS in cancer cells is technically difficult, as electron transport chain inhibitors can increase or decrease ROS generation, while they also block oxidative phosphorylation and ATP synthesis. Mitochondria-targeted antioxidant compounds can scavenge ROS in the matrix compartment but do not act on ROS released to the IMS. We assessed the importance of mitochondrial ROS for tumor cell proliferation, survival, and for tumor xenograft growth by stably expressing a hydrogen peroxide (H2O2) scavenger, peroxiredoxin-5, in the mitochondrial IMS (IMS-Prdx5) in 143B osteosarcoma and HCT116 colorectal cancer cell lines. IMS-Prdx5 attenuates hypoxia-induced ROS signaling as assessed independently in cytosol and IMS, HIF-1α stabilization and activity, and cellular proliferation under normoxic and hypoxic culture conditions. It also suppressed tumor growth invivo. Stable expression of nondegradable HIF-1α only partially rescued proliferation in IMS-Prdx5-expressing cells, indicating that mitochondrial H2O2 signaling contributes to tumor cell proliferation and survival through HIF-dependent and HIF-independent mechanisms.

Spermidine Alleviates Intrauterine Hypoxia-Induced Offspring Newborn Myocardial Mitochondrial Damage in Rats by Inhibiting Oxidative Stress and Regulating Mitochondrial Quality Control.

Intrauterine hypoxia (IUH) increases the risk of cardiovascular diseases in offspring. As a reactive oxygen species (ROS) scavenger, polyamine spermidine (SPD) is essential for embryonic and fetal survival and growth. However, further studies on the SPD protection and mechanisms for IUH-induced heart damage in offspring are required. This study aimed to investigate the preventive effects of prenatal SPD treatment on IUH-induced heart damage in newborn offspring rats and its underlying mitochondrial-related mechanism. The rat model of IUH was established by exposure to 10% O2 seven days before term. Meanwhile, for seven days, the pregnant rats were given SPD (5 mg.kg-1.d-1; ip). The one-day offspring rats were sacrificed to assess several parameters, including growth development, heart damage, cardiomyocytes proliferation, myocardial oxidative stress, cell apoptosis, and mitochondrial function, and have mitochondrial quality control (MQC), including mitophagy, mitochondrial biogenesis, and mitochondrial fusion/fission. In in vitro experiments, primary cardiomyocytes were subjected to hypoxia with or without SPD for 24 hours. IUH decreased body weight, heart weight, cardiac Ki67 expression, the activity of SOD, and the CAT and adenosine 5'-triphosphate (ATP) levels and increased the BAX/BCL2 expression, and TUNEL-positive nuclei numbers. Furthermore, IUH also caused mitochondrial structure abnormality, dysfunction, and decreased mitophagy (decreased number of mitophagosomes), declined mitochondrial biogenesis (decreased expression of SIRT-1, PGC-1α, NRF-2, and TFAM), and led to fission/fusion imbalance (increased percentage of mitochondrial fragments, increased DRP1 expression, and decreased MFN2 expression) in the myocardium. Surprisingly, SPD treatment normalized the variations in the IUH-induced parameters. Furthermore, SPD also prevented hypoxia-induced ROS accumulation, mitochondrial membrane potential decay, and the mitophagy decrease in cardiomyocytes. Maternal SPD treatment caused IUH-induced heart damage in newborn offspring rats by improving the myocardial mitochondrial function via anti-oxidation and anti-apoptosis, and regulating MQC.

Hypoxia-Induced GST1 Exerts Protective Effects on Trophoblasts via Inhibiting Reactive Oxygen Species (ROS) Accumulation

Hypoxic conditions are a typical extrinsic factor for the modification of trophoblast biological functions, including cell proliferation, migration, and invasion. Hypoxia-induced reactive oxygen species (ROS) accumulation causes chronic trophoblast injury and contributes to preeclampsia (PE). Glutathione-S-transferase P (GSTP1) is a main regulator of ROS. However, it is still unknown whether GSTP1 is involved in ROS regulation under hypoxic conditions. Here, we investigated the expression level of GSTP1 in first-trimester villi placentas compared with full-term placentas and the effect of hypoxic conditions on GSTP1. GSTP1 expression in first-trimester villi placentas was much higher than that in full-term placentas. After hypoxia exposure, GSTP1 was significantly upregulated in JEG3 cells, a trophoblast-like cell line. Hypoxic-induced GSTP1 scavenged ROS accumulated by hypoxia exposure, potentially by promoting GST activity. The inhibitory effects of hypoxia exposure on cell proliferation, migration, and invasion induced by hypoxia exposure were obviously reversed by overexpression of GSTP1. Hypoxia-induced cell apoptosis was also reversed by GSTP1 overexpression, indicating the protective effects of GSTP1 against ROS-induced cell injury. Moreover, overexpressed GSTP1 markedly promoted the cell proliferation, migration, invasion, and colony formation abilities in JEG3 cells, demonstrating that GSP1 also exerts promoting effects under normoxic conditions. These data show that hypoxia-induced GSTP1 expression facilitates trophoblast cell proliferation, migration, and invasion and exerts protective effects under hypoxic conditions, which may play an important role during the increase in PE.

Hypoxia-induced ROS aggravate tumor progression through HIF-1α-SERPINE1 signaling in glioblastoma.

Hypoxia, as an important hallmark of the tumor microenvironment, is a major cause of oxidative stress and plays a central role in various malignant tumors, including glioblastoma. Elevated reactive oxygen species (ROS) in a hypoxic microenvironment promote glioblastoma progression; however, the underlying mechanism has not been clarified. Herein, we found that hypoxia promoted ROS production, and the proliferation, migration, and invasion of glioblastoma cells, while this promotion was restrained by ROS scavengers N-acetyl-L-cysteine (NAC) and diphenyleneiodonium chloride (DPI). Hypoxia-induced ROS activated hypoxia-inducible factor-1α (HIF-1α) signaling, which enhanced cell migration and invasion by epithelial-mesenchymal transition (EMT). Furthermore, the induction of serine protease inhibitor family E member 1 (SERPINE1) was ROS-dependent under hypoxia, and HIF-1α mediated SERPINE1 increase induced by ROS via binding to the SERPINE1 promoter region, thereby facilitating glioblastoma migration and invasion. Taken together, our data revealed that hypoxia-induced ROS reinforce the hypoxic adaptation of glioblastoma by driving the HIF-1α-SERPINE1 signaling pathway, and that targeting ROS may be a promising therapeutic strategy for glioblastoma.

Hypoxia-induced reactive oxygen species in organ and tissue fibrosis

Fibrosis is the end-stage change of damaged tissues in various human diseases, which can lead to permanent scarring or organ malfunction. Hypoxia leads to oxidative stress, mitochondrial dysfunction, and inflammation in dysfunctional organs and tissues. Oxidative stress resulting from the overproduction of reactive oxygen species plays a central role in the fibrosis of injured organs. This review addresses the updated knowledge of the relationship between hypoxia and tissue fibrosis mediated by the reactive oxygen species pathway. Moreover, novel anti-fibrotic strategies are discussed, which may suppress reactive oxygen species and organ fibrosis.

The evolutionarily conserved hif-1/bnip3 pathway promotes mitophagy and mitochondrial fission in crustacean testes during hypoxia.

The hypoxia-inducible factor 1 (HIF-1) cascade is an ancient and strongly evolutionarily conserved signaling pathway that is involved in the hypoxic responses of most metazoans. Despite immense advances in the understanding of the HIF-1-mediated regulation of hypoxic responses in mammals, the contribution of the hif-1 cascade in the hypoxic adaptation of nonmodel invertebrates remains unclear. In this study, we used the oriental river prawn Macrobrachium nipponense for investigating the roles of hif-1-regulated mitophagy in crustacean testes under hypoxic conditions. We identified that the Bcl-2/adenovirus E1B 19-kDa interacting protein (bnip3) functions as a regulator of mitophagy in M. nipponense and demonstrated that hif-1α activates bnip3 by binding to the bnip3 promoter. Hif-1α knockdown suppressed the expression of multiple mitophagy-related genes, and prawns with hif-1α knockdown exhibited higher mortality under hypoxic conditions. We observed that the levels of BNIP3 were induced under hypoxic conditions and detected that bnip3 knockdown inhibited the mitochondrial translocation of dynamin-related protein 1 (drp1), which is associated with mitochondrial fission. Notably, bnip3 knockdown inhibited hypoxia-induced mitophagy and aggravated the deleterious effects of hypoxia-induced reactive oxygen species (ROS) production and apoptosis. The experimental studies demonstrated that hypoxia induced mitochondrial fission in M. nipponense via drp1. Altogether, the study elucidated the mechanism underlying hif-1/bnip3-mediated mitochondrial fission and mitophagy and demonstrated that this pathway protects crustaceans against ROS production and apoptosis induced by acute hypoxia.

Hypoxia-Induced Oxidative Stress Promotes Proteasome Inhibitor Resistance Via Upregulation of Heme Oxygenase-1 in Multiple Myeloma

Background Multiple myeloma (MM) is a hematopoietic malignancy for which proteasome inhibitors have become available in recent years. However, many patients develop resistance to these drugs during treatment. Therefore, it is important to elucidate the mechanisms underlying resistance acquisition by proteasome inhibitors. Side population (SP) cells, which have a high drug efflux capacity, as well as hypoxic responses in the microenvironment, have both provided important insights into drug resistance in MM; however, little is known about the characteristics of SP cells in hypoxic microenvironments. Aim and Methods To find novel therapeutic target for drug resistant MM cells, the SP cells and non-SP cells of MM cell lines (RPMI-8226 and KMS-11) were sorted for normoxic and hypoxic cultures (1% O2) for 48 h, respectively, and cDNA microarray assays were performed on these samples. Then, we conducted functional analysis of hypoxia-SP specific genes. Results Our comprehensive gene expression analysis identified four coding genes (HMOX1, BACH2, DUX4, and RASGEF1B) and seven non-coding genes (TUSC8, LOC101928738, lnc-WRAP73-1, LINC-PINT, LINC01004, MIR146A, and lnc-FAM133B-1) that are specifically highly expressed in SP cells under hypoxic conditions. Among protein-coding genes, RT-qPCR showed very low expression of BACH2 and no expression of DUX4; we decided to investigate the function of HMOX1/heme oxygenase-1 (HO-1) in hypoxic environments. One of the functions of HO-1 is to protect cells from apoptosis induced by reactive oxygen species (ROS). We found a significant increase in ROS under hypoxic conditions compared with normoxic conditions in MM cells, including MM patient samples. HMOX1 knockdown significantly increased ROS levels under both normoxic and hypoxic conditions. These results suggest that hypoxic stress induced ROS and that HO-1 can neutralize hypoxia-induced ROS. The addition of PMA, a ROS inducer, significantly increased HMOX1/HO-1 in MM cells. Conversely, the addition of NAC, a ROS neutralizer, suppressed HMOX1/HO-1 expression under hypoxic conditions. These results suggest that HO-1 is induced in hypoxic environments by a ROS-mediated pathway. Next, we investigated the involvement of HO-1 in the effects of proteasome inhibitors in hypoxic environments. MTX assays showed that bortezomib against HMOX1 knockdown KMS-11 reduced cell viability under hypoxic rather than normoxic conditions. We transplanted HMOX1 knockdown or control KMS-11 (1×106 cells) into immunodeficient mice, injected bortezomib (1.0 mg/kg) intraperitoneally on days 14 and 18, and sacrificed the mice on day 22. There was no significant difference in subcutaneous tumor volume and weight between the control and HMOX1 knockdown cell lines, whereas HMOX1 knockdown resulted in a significant bortezomib-induced reduction in subcutaneous tumor volume and weight (p = 0.0009 and 0.0096, respectively). Lastly, we examined whether excessive levels of ROS enhance the effect of bortezomib. PMA and a low concentration of bortezomib (5 nM, which is lower than that for IC50) were added to KMS-11 and RPMI-8226, and an apoptosis assay was performed. As a result, PMA or a low concentration of bortezomib increased apoptotic cells by only a small percentage, while simultaneous exposure to both significantly increased apoptotic cells synergistically. This result indicates that excessive ROS levels enhance the anti-myeloma effect of proteasome inhibitors. Additionally, in clinical datasets, HMOX1 had a strong and significantly positive correlation with MAFB, but not MAF. We investigated whether MAFB actually regulates HMOX1 under hypoxic conditions. MAFB/MafB was induced by hypoxia even in a cell line without t(14;20) (q32;q12), such as KMS-11. Knockdown of MAFB significantly decreased HMOX1/HO-1 expression only under hypoxic condition, suggesting that MafB induction is involved in the elevated expression of HO-1 under hypoxic conditions. Conclusion We clarified the contribution of the hypoxia-ROS-HO-1 axis to proteasome inhibitor resistance in hypoxic environments. This axis might also be involved in hypoxia-induced MafB expression. Because mechanisms that reduce excessive ROS in hypoxic microenvironments are thought to be closely related to cell survival and drug resistance, targeting this mechanism may be a new strategy to overcome drug resistance in refractory MM.

Targeting Mitochondrial ROS Production to Reverse the Epithelial-Mesenchymal Transition in Breast Cancer Cells.

Experimental evidence implicates reactive oxygen species (ROS) generation in the hypoxic stabilization of hypoxia-inducible factor (HIF)-1α and in the subsequent expression of promoters of tumor invasiveness and metastatic spread. However, the role played by mitochondrial ROS in hypoxia-induced Epithelial-Mesenchymal Transition (EMT) activation is still unclear. This study was aimed at testing the hypothesis that the inhibition of hypoxia-induced mitochondrial ROS production, mainly at the mitochondrial Complex III UQCRB site, could result in the reversion of EMT, in addition to decreased HIF-1α stabilization. The role of hypoxia-induced ROS increase in HIF-1α stabilization and the ability of antioxidants, some of which directly targeting mitochondrial Complex III, to block ROS production and HIF-1α stabilization and prevent changes in EMT markers were assessed by evaluating ROS, HIF-1α and EMT markers on breast cancer cells, following 48 h treatment with the antioxidants. The specific role of UQCRB in hypoxia-induced EMT was also evaluated by silencing its expression through RNA interference and by assessing the effects of its downregulation on ROS production, HIF-1α levels, and EMT markers. Our results confirm the pivotal role of UQCRB in hypoxic signaling inducing EMT. Thus, UQCRB might be a new therapeutic target for the development of drugs able to reverse EMT by blocking mitochondrial ROS production.

Theranostic Trigger-Responsive Carbon Monoxide-Generating Microbubbles.

Carbon monoxide (CO) is a gaseous signaling molecule that modulates inflammation, cell survival, and recovery after myocardial infarction. However, handling and dosing of CO as a compressed gas are difficult. Here, light-triggerable and magnetic resonance imaging (MRI)-detectable CO release from dimanganese decacarbonyl (CORM-1) are demonstrated, and the development of CORM-1-loaded polymeric microbubbles (COMB) is described as an ultrasound (US)- and MRI-imageable drug delivery platform for triggerable and targeted CO therapy. COMB are synthesized via a straightforward one-step loading protocol, present a narrow size distribution peaking at 2µm, and show excellent performance as a CORM-1 carrier and US contrast agent. Light irradiation of COMB induces local production and release of CO, as well as enhanced longitudinal and transversal relaxation rates, enabling MRI monitoring of CO delivery. Proof-of-concept studies for COMB-enabled light-triggered CO release show saturation of hemoglobin with CO in human blood, anti-inflammatory differentiation of macrophages, reduction of hypoxia-induced reactive oxygen species (ROS) production, and inhibition of ischemia-induced apoptosis in endothelial cells and cardiomyocytes. These findings indicate that CO-generating MB are interesting theranostic tools for attenuating hypoxia-associated and ROS-mediated cell and tissue damage in cardiovascular disease.

Hypoxia Induces Proliferation via NOX4-Mediated Oxidative Stress and TGF-β3 Signaling in Uterine Leiomyoma Cells

ABSTRACT Uterine leiomyomas, the most common tumors of the female reproductive system, are known to have a hypoxic microenvironment. However, the role of such environment in leiomyoma pathobiology remains unknown. The objective was to determine the effects of hypoxia on leiomyoma cells, and the mechanisms. We found that hypoxia induces proliferation and inhibits apoptosis in human leiomyoma cells. This pro-proliferative effect was accompanied by an increase in reactive oxygen species (ROS) generation and the expression of NADPH oxidase 4 (NOX4). The specific NOX4 inhibitor GLX351322 abrogated this hypoxia-induced ROS generation, cellular proliferation, and apoptosis inhibition. To further investigate the mechanism of NOX4-mediated proliferation, we treated leiomyoma cells grown in normoxia with media from leiomyoma cells cultured under hypoxia. This resulted in increased ROS generation and NOX4 expression, suggesting the hypoxia-induced effects are mediated by an autocrine mechanism. We worked to identify the nature of this autocrine factor. We found that the expression of TGF-β3 and its downstream signaling target pSmad3, are increased in hypoxic leiomyoma cells. To examine the hypothesis that TGF-β3 is, at least, a part of this autocrine mechanism, we treated hypoxic leiomyoma cells with the HIF-1α inhibitor KC7F2 which we discovered to ameliorate the hypoxia-induced TGF-β3 expression. Furthermore, pharmacologic inhibition with the TGF-β/Smad inhibitor SB431542 reduced hypoxia-induced NOX4 expression and ROS generation and attenuated cell proliferation. Thus, we have identified a novel mechanism by which hypoxia induces proliferation in leiomyoma cells. This finding adds to our understanding of leiomyoma pathobiology and can help in identifying new therapeutic targets. Supplemental data for this article can be accessed here .

Effects of Hypoxic Environment on Periodontal Tissue through the ROS/TXNIP/NLRP3 Inflammasome Pathway.

There is low evidence for the possible association between obstructive sleep apnea-hypopnea syndrome (OSAHS) and periodontitis, necessitating further research. This study was aimed at investigating this association. For the in vitro study, 8-day-old Wistar rats were divided into the unilateral nasal obstruction group (UNO) and the sham surgery group (SHAM). Rats in the former group were subjected to UNO by cauterization of the external nostril at the age of 8 days. Immunofluorescence analysis, quantitative real-time polymerase chain reaction, and western blot were performed to assess the expression of thioredoxin-interacting protein (TXNIP), NLR family pyrin domain-containing 3 (NLRP3) inflammasome-associated factors, and interleukin-1β (IL-1β). Throughout the experimental period, the weights of rats in the two groups were similar. The mRNA and protein expression of TXNIP and IL-1β was significantly higher in the UNO than in the SHAM groups. Compared with SHAM, NLRP3 inflammasome-associated factors were activated in the UNO group. For the in vitro study, a cellular hypoxia model was established by treating human periodontal ligament cells (HPDLCs) with cobalt chloride. The studies showed that hypoxia can induce an excessive production and accumulation of reactive oxygen species (ROS) in HPDLCs and induce abnormal expression of TNXIP, NLRP3 inflammasome-related factors, and IL-1β. More importantly, N-acetylcysteine induced reduction of ROS in HPDLCs, downregulated TXNIP expression, inhibited the expression and aggregation of NLRP3 inflammasome-related factors, and abrogated the inflammatory response to hypoxia. In conclusion, hypoxia-induced ROS can activate the TXNIP/NLRP3 inflammasome signaling pathway in response to oxidative stress, resulting in the increased expression of inflammatory factors in HPDLCs. Our findings provide evidence for the mechanism underlying the possible association between OSAHS and periodontal disease.

Yishen Huoxue decoction attenuates unilateral ureteric obstruction-induced renal fibrosis and hypoxia-induced reactive oxygen species generation via adenosine monophosphate-activated protein kinase / peroxisome proliferator-activated receptor coactivator-1α / silent mating-type information regulation 2 homolog 3 pathway.

To investigate the effeicacy of Yishen Huoxue decoction (YSHX) on renal fibrosis induced by unilateral ureteric obstruction (UUO), and on reactive oxygen species (ROS) homeostasis in human umbilical vein endothelial cells (HUVECs). Forty male mice were randomly divided into six groups, sham group, UUO group, UUO+ resveratrol (RSV) (15 mg/kg) group, UUO + YSHX 20 mg/kg group (UUO + YSHX-L), UUO + YSHX 40 mg/kg group (UUO + YSHX-M), UUO + YSHX 80 mg/kg group (UUO + YSHX-H). Western blotting was used to measure protein expression levels. Reverse transcription-quantitative polymerase chain reaction was used to measure the mRNA expression. Immunohistochemistry was used to examine the histopathological changes of kidney tissue sample. Cell apoptosis was measured by Annexin V/PI staining. Cell viability was measured using CCK-8/WST-8 assay. YSHX treatment reduced α-SMA and Col-4 expressions, and increased CD31 and VE-cadherin expressions in UUO model mice. In vitro, YSHX increased cell viability and decreased apoptosis of HUVECs under hypoxic conditions. YSHX inhibited ROS generation by activating adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor coactivator-1α (PGC-1α)/silent mating-type information regulation 2 homolog 3 (Sirt3) signaling. YSHX treatment reduced 109KJ UUO-induced renal injury and fibrosis. Furthermore, YSHX treatment attenuated hypoxia-induced oxidative stress by regulating AMPK/PGC-1α/Sirt3 signaling.

Hypoxia Induces Renal Epithelial Injury and Activates Fibrotic Signaling Through Up-Regulation of Arginase-II.

The ureohydrolase, type-II arginase (Arg-II), is a mitochondrial enzyme metabolizing L-arginine into urea and L-ornithine and is highly expressed in renal proximal tubular cells (PTC) and upregulated by renal ischemia. Recent studies reported contradictory results on the role of Arg-II in renal injury. The aim of our study is to investigate the function of Arg-II in renal epithelial cell damage under hypoxic conditions. Human renal epithelial cell line HK2 was cultured under hypoxic conditions for 12–48 h. Moreover, ex vivo experiments with isolated kidneys from wild-type (WT) and genetic Arg-II deficient mice (Arg-II–/–) were conducted under normoxic and hypoxic conditions. The results show that hypoxia upregulates Arg-II expression in HK2 cells, which is inhibited by silencing both hypoxia-inducible factors (HIFs) HIF1α and HIF2α. Treatment of the cells with dimethyloxaloylglycine (DMOG) to stabilize HIFα also enhances Arg-II. Interestingly, hypoxia or DMOG upregulates transforming growth factor β1 (TGFβ1) levels and collagens Iα1, which is prevented by Arg-II silencing, while TGFβ1-induced collagen Iα1 expression is not affected by Arg-II silencing. Inhibition of mitochondrial complex-I by rotenone abolishes hypoxia-induced reactive oxygen species (mtROS) and TGFβ1 elevation in the cells. Ex vivo experiments show elevated Arg-II and TGFβ1 expression and the injury marker NGAL in the WT mouse kidneys under hypoxic conditions, which is prevented in the Arg-II–/– mice. Taking together, the results demonstrate that hypoxia activates renal epithelial HIFs-Arg-II-mtROS-TGFβ1-cascade, participating in hypoxia-associated renal injury and fibrosis.

An Insight into Sesamolin: Physicochemical Properties, Pharmacological Activities, and Future Research Prospects.

Sesame seeds are rich in lignan content and have been well-known for their health benefits. Unlike the other sesame lignan compounds (i.e., sesamin and sesamol), the study of the pharmacological activity of sesamolin has not been explored widely. This review, therefore, summarizes the information related to sesamolin’s pharmacological activities, and the mechanism of action. Moreover, the influence of its physicochemical properties on pharmacological activity is also discussed. Sesamolin possessed neuroprotective activity against hypoxia-induced reactive oxygen species (ROS) and oxidative stress in neuron cells by reducing the ROS and inhibiting apoptosis. In skin cancer, sesamolin exhibited antimelanogenesis by affecting the expression of the melanogenic enzymes. The anticancer activity of sesamolin based on antiproliferation and inhibition of migration was demonstrated in human colon cancer cells. In addition, treatment with sesamolin could stimulate immune cells to enhance the cytolytic activity to kill Burkitt’s lymphoma cells. However, the toxicity and safety of sesamolin have not been reported. And there is also less information on the experimental study in vivo. The limited aqueous solubility of sesamolin becomes the main problem, which affects its pharmacological activity in the in vitro experiment and clinical efficacy. Therefore, solubility enhancement is needed for further investigation and determination of its pharmacological activity profiles. Since there are fewer reports studying this issue, it could become a future prospective research opportunity.

Impact of moderate altitude exposure on cardiovascular risk

Acute exposure to extreme altitude increases arterial stiffness by activation of the sympathetic and endothelin system as well as hypoxia-induced reactive oxygen species production. Beyond a certain individual threshold, these physiological adaptations represent a relevant cardiovascular risk factor. In this pilot study we investigated to what extent temporary exposure to moderate altitude, as present during hiking, skiing or in aeroplanes, leads to changes in vascular tone. Pulse wave parameters of 8 healthy individuals were assessed with a BR-102 plus pulse wave analyser (Schiller, Germany) at baseline (521 m) and after 24 h exposure to moderate altitude (2650 m). We identified a significant increase in heart rate (61 vs. 68/min, p = 0.021) as well as changes in central (35.6 vs. 41.4 mmHg, p = 0.024) and peripheral pulse pressure (44.7 vs. 52.6 mmHg, p = 0.006). Amplitudes of forward (21.6 vs. 25.4 mmHg, p = 0.012) and backward pulse waves (15.3 vs. 17.6 mmHg, p = 0.043) were significantly elevated. Pulse wave velocity showed no significant change from 5.8 m/s at baseline to 6.1 m/s at moderate altitude (p = 0.056). We show that temporary exposure to moderate altitude leads to mild changes in vascular tone reflected by pulse pressure and pulse wave amplitude in healthy adults. Although the observed effects were mild in our study, it indicates that adaptation capacity is of crucial importance and any restrictions by disease or simply with the process of ageing demand increased awareness, even in moderate altitude.