Cardiac macrophages regulate isoproterenol-induced Takotsubo-like cardiomyopathy.

Takotsubo syndrome (TTS) is an acute, stress-induced cardiomyopathy that occurs predominantly in women after extreme physical and/or emotional stress. To date, our understanding of the molecular basis for TTS remains unknown and, consequently, specific therapies are lacking. Myocardial infiltration of monocytes and macrophages in TTS has been documented in clinical studies. However, the functional importance of these findings remains poorly understood. Here, we show that a single high dose of isoproterenol (ISO) in mice induced a TTS-like cardiomyopathy phenotype characterized by female predominance, severe cardiac dysfunction, and robust myocardial infiltration of macrophages. Single-cell RNA-Seq studies of myocardial immune cells revealed that TTS-like cardiomyopathy is associated with complex activation of innate and adaptive immune cells in the heart, and macrophages were identified as the dominant immune cells. Global macrophage depletion (via clodronate liposome administration) or blockade of macrophage infiltration (via a CCR2 antagonist or in CCR2-KO mice) resulted in recovery of cardiac dysfunction in ISO-challenged mice. In addition, damping myeloid cell activation by HIF1α deficiency or exposure to the immunomodulatory agent bortezomib ameliorated ISO-induced cardiac dysfunction. Collectively, our findings identify macrophages as a critical regulator of TTS pathogenesis that can be targeted for therapeutic gain.

STING up-regulates VEGF expression in oxidative stress-induced senescence of retinal pigment epithelium via NF-κB/HIF-1α pathway.

AIM: Aging-related dysfunction of retinal pigment epithelium (RPE) is the main pathogenic factors for pathological angiogenesis due to dysregulated vascular endothelial growth factor (VEGF) in retinal vascular diseases such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). However, the molecular mechanism behind the up-regulation of VEGF in senescent RPE is still blurred. MATERIALS AND METHODS: As oxidative damage is the key cause of RPE dysfunction, we employed a model of oxidative stress-induced premature senescence of ARPE-19 to explore the effect of senescent RPE on VEGF. KEY FINDINGS: We reported that senescent ARPE-19 up-regulated VEGF expression under both short-term and prolonged H2O2 treatment, accompanying with increased HIF-1α, the key mediator of VEGF. STING signaling, which could be activated by oxidative stress-damaged DNA, was also observed to be increased in senescent ARPE-19 treated with H2O2. And the inhibition of STING significantly reduced HIF-1α expression to alleviate the up-regulation of VEGF. NF-κB was also shown to be involved in the regulation of VEGF in senescent ARPE-19 in response to STING signaling. Furthermore, oxidative stress impaired the lysosomal clearance of damaged DNA to enhance STING signaling, thereby up-regulating VEGF expression in senescent RPE. SIGNIFICANCE: Our data provide evidence that STING plays an important role in VEGF regulation in senescent RPE induced by oxidative stress.

Transcription Factor ChREBP Mediates High Glucose-Evoked Increase in HIF-1α Content in Epithelial Cells of Renal Proximal Tubules.

Hyperglycemia/diabetes appears to be accompanied by the state of hypoxia, which especially affects kidneys. The aim of the study was to elucidate the mechanism of high glucose action on HIF-1α expression in renal proximal tubule epithelial cells. The research hypotheses included: (1) the participation of transcription factor ChREBP; and (2) the involvement of the effects resulting from pseudohypoxia, i.e., lowered intracellular NAD+/NADH ratio. The experiments were performed on HK-2 cells and primary cells: D-RPTEC (Diseased Human Renal Proximal Tubule Epithelial Cells-Diabetes Type II) and RPTEC (Renal Proximal Tubule Epithelial Cells). Protein and mRNA contents were determined by Western blot and RT-qPCR, respectively. ChREBP binding to DNA was detected applying chromatin immunoprecipitation, followed by RT-qPCR. Gene knockdown was performed using siRNA. Sirtuin activity and NAD+/NADH ratio were measured with commercially available kits. It was found that high glucose in HK-2 cells incubated under normoxic conditions: (1) activated transcription of HIF-1 target genes, elevated HIF-1α and ChREBP content, and increased the efficacy of ChREBP binding to promoter region of HIF1A gene; and (2), although it lowered NAD+/NADH ratio, it affected neither sirtuin activity nor HIF-1α acetylation level. The stimulatory effect of high glucose on HIF-1α expression was not observed upon the knockdown of ChREBP encoding gene. Experiments on RPTEC and D-RPTEC cells demonstrated that HIF-1α content in diabetic proximal tubular cells was lower than that in normal ones but remained high glucose-sensitive, and the latter phenomenon was mediated by ChREBP. Thus, it is concluded that the mechanism of high glucose-evoked increase in HIF-1α content in renal proximal tubule endothelial cells involves activation of ChREBP, indirectly capable of HIF1A gene up-regulation.

Protective Effects of Glutamine and Leucine Supplementation on Sepsis-Induced Skeletal Muscle Injuries.

This study investigated the effects of l-glutamine (Gln) and/or l-leucine (Leu) administration on sepsis-induced skeletal muscle injuries. C57BL/6J mice were subjected to cecal ligation and puncture to induce polymicrobial sepsis and then given an intraperitoneal injection of Gln, Leu, or Gln plus Leu beginning at 1 h after the operation with re-injections every 24 h. All mice were sacrificed on either day 1 or day 4 after the operation. Blood and muscles were collected for analysis of inflammation and oxidative damage-related biomolecules. Results indicated that both Gln and Leu supplementation alleviated sepsis-induced skeletal muscle damage by reducing monocyte infiltration, calpain activity, and mRNA expression levels of inflammatory cytokines and hypoxia-inducible factor-1α. Furthermore, septic mice treated with Gln had higher percentages of blood anti-inflammatory monocytes and muscle M2 macrophages, whereas Leu treatment enhanced the muscle expressions of mitochondrion-related genes. However, there were no synergistic effects when Gln and Leu were simultaneously administered. These findings suggest that both Gln and Leu had prominent abilities to attenuate inflammation and degradation of skeletal muscles in the early and/or late phases of sepsis. Moreover, Gln promoted the switch of leukocytes toward an anti-inflammatory phenotype, while Leu treatment maintained muscle bioenergetic function.

Hypoxia-Inducible Factor-1α in Macrophages, but Not in Neutrophils, Is Important for Host Defense during Klebsiella pneumoniae-Induced Pneumosepsis.

Hypoxia-inducible factor- (HIF-) 1α has been implicated in the ability of cells to adapt to alterations in oxygen levels. Bacterial stimuli can induce HIF1α in immune cells, including those of myeloid origin. We here determined the role of myeloid cell HIF1α in the host response during pneumonia and sepsis caused by the common human pathogen Klebsiella pneumoniae. To this end, we generated mice deficient for HIF1α in myeloid cells (LysM-cre × Hif1α fl/fl) or neutrophils (Mrp8-cre × Hif1α fl/fl) and infected these with Klebsiella pneumoniae via the airways. Myeloid, but not neutrophil, HIF1α-deficient mice had increased bacterial loads in the lungs and distant organs after infection as compared to control mice, pointing at a role for HIF1α in macrophages. Myeloid HIF1α-deficient mice did not show increased bacterial growth after intravenous infection, suggesting that their phenotype during pneumonia was mediated by lung macrophages. Alveolar and lung interstitial macrophages from LysM-cre × Hif1α fl/fl mice produced lower amounts of the immune enhancing cytokine tumor necrosis factor upon stimulation with Klebsiella, while their capacity to phagocytose or to produce reactive oxygen species was unaltered. Alveolar macrophages did not upregulate glycolysis in response to lipopolysaccharide, irrespective of HIF1α presence. These data suggest a role for HIF1α expressed in lung macrophages in protective innate immunity during pneumonia caused by a common bacterial pathogen.

Mechanical stimulation of chondrocytes regulates HIF-1α under hypoxic conditions.

We investigated the effects of hypoxia-inducible factor (HIF)-1α on articular cartilage under mechanical stimulation and the associated mechanisms. Chondrocytes, isolated from articular cartilage from the knee, hip, and shoulder joints of Wistar rats, were subjected to 20 % tensile stress under hypoxic (5% O2) conditions for 24 h. HIF-1α and aggrecan expression was significantly enhanced with mechanical stimulation under hypoxia but not significantly altered with mechanical stimulation under normoxia. The nuclear translocation of HIF-1α was enhanced by mechanical stress under hypoxia. Under both normoxia and hypoxia, a disintegrin and metalloproteinase with thrombospondin motifs (ADAM-TS) 5 expression was significantly reduced with mechanical stimulation compared to that in the group without mechanical stimulation. However, HIF-1α knockdown mitigated changes in aggrecan and ADAM-TS5 expression mediated by mechanical stimulation under hypoxia. The effects of treadmill running on HIF-1α production in the articular cartilage of rat knee joints were also analyzed. HIF-1α production increased in the moderate running group and decreased to the same levels as those in the control group in the excessive running group. This suggests that HIF-1α regulates aggrecan and ADAM-TS5 expression in response to mechanical stimulation under hypoxia and general mechanical stimulation in articular cartilage under hypoxia, while controlling cartilage homeostasis.

MicroRNA-210-3p is transcriptionally upregulated by hypoxia induction and thus promoting EMT and chemoresistance in glioma cells.

BACKGROUND: Glioma is the most common and lethal form of brain cancer. It is highly malignant and is often characterized by chemoresistance and radioresistance, which are thought to mainly result from hypoxic microenvironments. Various tumour-promoting and tumour-suppressing microRNAs (miRNAs) have been identified in gliomas; however, it is still largely unknown how miRNAs are modified by hypoxia and subsequently affect glioma. In this study, we examined the expression of miR-210-3p, a well-characterized miRNA that responds to hypoxia in glioma cell lines. METHODS: The expressions of miR-9 and miR-210-3p were analysed by using qPCR. Cell viability was measured by performing CCK-8 after eechinomycin treatment or introduction of miR-210 for 24 or 48 h. The correlation of HIF-1α expression with TGF-ß were analysed using the REMBRANDT database. The biomarkers of EMT, including E-cadherin, N-cadherin and Vimentin, were detected by western blot. Apoptotic cell death was measured by performing Annexin V-FITC/PI double staining followed by flow cytometry. RESULTS: We found that miR-210-3p was induced by a mechanism dependent on the hypoxia-induced transcriptional activity of HIF-1α. Then we established a positive association between the HIF-1α and TGF-ß expression levels, and miR-210-3p upregulation induced TGF-ß expression, indicating that hypoxia-induced HIF-1α activity upregulated TGF-ß via miR-210-3p upregulation. Hypoxia-induced miR-210-3p activity was found to promote EMT by upregulating TGF-ß, which subsequently enhanced the invasive ability in U87-MG cells. We further confirmed that miR-210-3p induced chemoresistance to TMZ in U87-MG cells via TGF-ß upregulation under hypoxic conditions. CONCLUSION: These results help to reveal the potential regulatory mechanisms of hypoxia-induced miR-210-3p expression that affect malignant behaviors and chemoresistance via TGF-ß upregulation in glioma cells.

Gene expression profiles during tissue remodeling following bladder outlet obstruction.

Bladder outlet obstruction (BOO) often results in lower urinary tract symptoms (LUTSs) and negatively affects quality of life. Here, we evaluated gene expression patterns in the urinary bladder during tissue remodeling due to BOO. We divided BOO model rats into two groups according to the degree of hypertrophy of smooth muscle in the bladder. The strong muscular hypertrophy group, which exhibited markedly increased bladder smooth muscle proportion and HIF1α mRNA levels compared with the control group, was considered a model for the termination of hypertrophy, whereas the mild muscular hypertrophy group was considered a model of the initiation of hypertrophy. Some genes related to urinary function showed different expression patterns between the two groups. Furthermore, we found that several genes, including D-box binding PAR bZIP transcription factor (DBP), were upregulated only in the mild muscular hypertrophy group. DBP expression levels were increased in bladder smooth muscle cells in response to hypoxic stress. DBP associated with enhancer and promoter regions of NOS3 gene locus and upregulated NOS3 gene expression under hypoxic conditions. These findings suggested that the regulatory systems of gene expression were altered during tissue remodeling following BOO. Furthermore, circadian clock components might be involved in control of urinary function via transcriptional gene regulation in response to hypoxic stimuli.

HIF-1α and HIF-2α redundantly promote retinal neovascularization in patients with ischemic retinal disease.

Therapies targeting VEGF have proven only modestly effective for the treatment of proliferative sickle cell retinopathy (PSR), the leading cause of blindness in patients with sickle cell disease. Here, we shift our attention upstream from the genes that promote retinal neovascularization (NV) to the transcription factors that regulate their expression. We demonstrated increased expression of HIF-1α and HIF-2α in the ischemic inner retina of PSR eyes. Although both HIFs participated in promoting VEGF expression by hypoxic retinal Müller cells, HIF-1 alone was sufficient to promote retinal NV in mice, suggesting that therapies targeting only HIF-2 would not be adequate to prevent PSR. Nonetheless, administration of a HIF-2-specific inhibitor currently in clinical trials (PT2385) inhibited NV in the oxygen-induced retinopathy (OIR) mouse model. To unravel these discordant observations, we examined the expression of HIFs in OIR mice and demonstrated rapid but transient accumulation of HIF-1α but delayed and sustained accumulation of HIF-2α; simultaneous expression of HIF-1α and HIF-2α was not observed. Staggered HIF expression was corroborated in hypoxic adult mouse retinal explants but not in human retinal organoids, suggesting that this phenomenon may be unique to mice. Using pharmacological inhibition or an in vivo nanoparticle-mediated RNAi approach, we demonstrated that inhibiting either HIF was effective for preventing NV in OIR mice. Collectively, these results explain why inhibition of either HIF-1α or HIF-2α is equally effective for preventing retinal NV in mice but suggest that therapies targeting both HIFs will be necessary to prevent NV in patients with PSR.

HIF-1α aggravated traumatic brain injury by NLRP3 inflammasome-mediated pyroptosis and activation of microglia.

Hypoxia inducible factor 1 alpha (HIF-1α) is involved in regulating the biological functions of neuronal death after traumatic brain injury (TBI), and attaches importance in the inflammatory response, but its potential mechanism is still unknown. Our study aimed to explore the regulatory mechanism between HIF-1α and NLRP3 inflammasome after TBI. Male mice underwent controlled cortical impact (CCI) or sham-operated procedures. Brain water content and blood-brain barrier permeability were measured at the indicated time after TBI. The behavioral performance, ELISA, immunofluorescence, and western blot analysis were used to determine whether HIF-1α specifically targeted TBI-induced pyroptosis. We discovered that TBI-induced brain injury caused by external mechanical forces is characterized by edema and blood-brain barrier disorder, and the release of IL-1ß, IL-18, and LDH and upregulation of HIF-1α expression, reaching the peak on the third day post-TBI. In addition, HIF-1α accumulated NLRP3 inflammasome-mediated pyroptosis and activation of microglia. The protein expressions of NLRP3, GSDMD, GSDMD-N, pro-caspase 1, and cleaved caspase 1 were markedly increased in the injured cortex, which were restored to normal levels by the interference of HIF-1α. The inactivation of HIF-1α conferred neuroprotection and alleviated brain injury after TBI. HIF-1α was implicated in TBI-induced brain injury, aggravated NLRP3 inflammasome -mediated pyroptosis, and the activation of microglia, which provided a potential target for treating TBI.

Melittin inhibits the expression of key genes involved in tumor microenvironment formation by suppressing HIF-1α signaling in breast cancer cells.

HIF-1α has critical roles in the formation of tumor microenvironment by regulating genes involved in angiogenesis and anaerobic respiration. TME fuels tumors' growth and metastasis and presents therapy with several challenges. Therefore, we aimed to investigate if Melittin disrupts HIF-1α signaling pathway in breast adenocarcinoma cell line MDA-MB-231. Breast adenocarcinoma cell line MDA-MB-231 was cultured in the presence of different doses of Melittin, and MTT assay was carried out to measure Melittin's cytotoxic effects. Cells were exposed to 5% O2 to mimic hypoxic conditions and Melittin. Western blot was used to measure HIF-1α protein levels. Gene expression analysis was performed using real-time PCR to measure relative mRNA abundance of genes involved in tumor microenvironment formation. Our results revealed that Melittin effectively inhibits HIF-1α at transcriptional and translational/post-translational level. HIF-1α protein and mRNA level were significantly decreased in Melittin-treated groups. It is found that inhibition of HIF-1α by Melittin is through downregulation of NFκB gene expression. Furthermore, gene expression analysis showed a downregulation in VEGFA and LDHA expression due to inhibition of HIF-1α protein by Melittin. In addition, cell toxicity assay showed that Melittin inhibits the growth of MDA-MB-231 cell line through activation of extrinsic and intrinsic apoptotic pathways by upregulating TNFA and BAX expression. Melittin suppresses the expression of genes responsible for formation of TME physiological hallmarks by suppressing HIF-1α signaling pathway. Our results suggest that Melittin can modulate tumor microenvironment by inhibition of VEGFA and LDHA.

Hyperbaric Oxygen Improves Cerebral Ischemia/Reperfusion Injury in Rats Probably via Inhibition of Autophagy Triggered by the Downregulation of Hypoxia-Inducing Factor-1 Alpha.

Ischemic stroke, accompanied with high mortality and morbidity, may produce heavy economic burden to societies and families. Therefore, it is of great significance to explore effective therapies. Hyperbaric oxygen (HBO) is a noninvasive, nondrug treatment method that has been proved able to save ischemic penumbra by improving hypoxia, microcirculation, and metabolism and applied in various ischemic diseases. Herewith, we fully evaluated the effect of HBO on ischemic stroke and investigated its potential mechanism in the rat ischemia/reperfusion(I/R) model. Sixty Sprague-Dawley male rats were randomly divided into three groups-sham group, MCAO group, and MCAO+HBO group. In the latter two groups, the middle cerebral artery occlusion was performed (MCAO) for 2 hours, and then the occlusion was removed in order to establish the ischemic/reperfusion model. Subsequently, HBO was performed immediately after I/R (2 hours per day for 3 days). 72 hours after MCAO, the brain was dissected for our experiment. Finally, the data from three groups were analyzed by one-way analysis of variance (ANOVA) and followed by a Bonferroni test. In this article, we reported that HBO effectively reduced the infarction and edema and improved neurological functions to a certain extent. As shown by western blot analysis, HBO significantly reduced autophagy by regulating autophagy-related proteins (mTOR, p-mTOR, Atg13, LC3B II and LC3B II) in the hippocampus 72 hours after I/R, which was accompanied by inhibiting the expression of hypoxia inducible factor-1α (HIF-1α) in hippocampus. The results suggest that HBO may improve cerebral I/R injury, possibly via inhibiting HIF-1α, the upstream molecule of autophagy, and therefore, subsequently inhibiting autophagy in the rat model of ischemic stroke.

Astaxanthin mediated regulation of VEGF through HIF1α and XBP1 signaling pathway: An insight from ARPE-19 cell and streptozotocin mediated diabetic rat model.

Breakdown of outer blood-retina barrier (BRB) has been associated with the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). Vascular endothelial growth factor (VEGF) might play a detrimental role in the pathogenesis of DME, a major clinical manifestation of DR. In the present study, we investigated the inhibitory mechanism of astaxanthin on VEGF and its upstream signaling pathways under in vitro and in vivo conditions. Astaxanthin has been observed to downregulate VEGF expression under hyperglycemic (HG) and CoCl2 induced hypoxic conditions in ARPE-19 cells. There were compelling pieces of evidence for the involvement of transcription factors like HIF1α and XBP1 in the upregulation of VEGF under HG and hypoxic conditions. Thus, we investigated the role of astaxanthin in the expression and nuclear translocation of HIF1α and XBP1. The activation and translocation of HIF1α and XBP1 induced by HG or CoCl2 conditions were hindered by astaxanthin. Additionally, treatment with HIF1α siRNA and IRE1 inhibitor STF-083010 also inhibited the expression of VEGF induced by HG and CoCl2 conditions. These results indicated that the anti-VEGF property of astaxanthin might be associated with the downregulation of HIF1α and XBP1. Furthermore, astaxanthin mitigated the enhanced migration of retinal pigment epithelial (RPE) cells under DR conditions. As well, astaxanthin protected disorganization of zona occludin-1 (ZO-1) tight junction protein in RPE and reduced HG or hypoxic induced permeability of RPE cells. In streptozotocin-induced diabetic rat model, astaxanthin reduced the expression of HIF1α, XBP1, and VEGF as well as protected the abnormalities in the retinal layers induced by diabetes condition. Thus, astaxanthin may be used as a potential nutraceutical to prevent or treat retinal dysfunction in diabetic patients.

Astragaloside IV improves angiogenesis under hypoxic conditions by enhancing hypoxia­inducible factor­1α SUMOylation.

Improving angiogenic capacity under hypoxic conditions is essential for improving the survival of skin grafts, as they often lack the necessary blood supply. The stable expression levels of hypoxia­inducible factor­1α (HIF­1α) in the nucleus directly affect the downstream vascular endothelial growth factor (VEGF) signaling pathway and regulate angiogenesis in a hypoxic environment. Astragaloside IV (AS­IV), an active component isolated from Astragalus membranaceus, has multiple biological effects including antioxidant and anti­diabetic effects, and the ability to provide protection from cardiovascular damage. However, the mechanisms underlying these effects have not previously been elucidated. The present study investigated whether AS­IV promotes angiogenesis via affecting the balance between ubiquitination and small ubiquitin­related modifier (SUMO) modification of HIF­1α. The results demonstrated that persistent hypoxia induces changes in expression levels of HIF­1α protein and significantly increases the proportion of dysplastic blood vessels. Further western blotting experiments showed that rapid attenuation and delayed compensation of SUMO1 activity is one of the reasons for the initial increase then decrease in HIF­1α levels. SUMO1 overexpression stabilized the presence of HIF­1α in the nucleus and decreased the extent of abnormal blood vessel morphology observed following hypoxia. AS­IV induces vascular endothelial cells to continuously produce SUMO1, stabilizes the HIF­1α/VEGF pathway and improves angiogenesis in hypoxic conditions. In summary, the present study confirmed that AS­IV stimulates vascular endothelial cells to continuously resupply SUMO1, stabilizes the presence of HIF­1α protein and improves angiogenesis in adverse hypoxic conditions, which may improve the success rate of flap graft surgery following trauma or burn.

Hypoxia and its possible relationship with endometrial receptivity in adenomyosis: a preliminary study.

BACKGROUND: Adenomyosis (AM) is an important cause of female infertility. However, the underlying mechanism remains unclear. This report describes a preliminary study of hypoxia and its possible association with endometrial receptivity in AM. METHODS: The study was divided into in vitro and in vivo experiments. In vitro, expression levels of the endometrial receptivity markers HOXA10 and HOXA11 in the implantation period were examined using real-time PCR and western blotting. Endometrial expression of hypoxia-inducible factor (HIF)-1α, HIF-2α, and HIF-3α was determined using immunohistochemistry. In vivo, using an AM mouse model established by oral administration of tamoxifen, we inhibited expression of HIF-2α using an HIF-2α antagonist (PT2399; 30 mg/kg body weight, twice daily by oral gavage for 2 days) and then examined expression levels of Hoxa10 and Hoxa11 using real-time PCR and western blotting. RESULTS: Endometrial mRNA and protein expression levels of HOXA10 and HOXA11 were significantly lower in patients with AM than in control patients. Expression of HIF-2α was significantly higher in the AM group than in the control group, whereas that of HIF-1α and HIF-3α was equivalent in both groups. In vivo analysis showed that administration of the HIF-2α antagonist resulted in increased expression of Hoxa10 and Hoxa11 at both the mRNA and protein levels in AM model mice. CONCLUSIONS: HIF-2α overexpression may be one reason for decreased endometrial receptivity in AM. The current findings provide insight into HIF-2α-mediated AM-related infertility and suggest that PT2399 has potential as a treatment for AM. TRIAL REGISTRATION: This trial was retrospectively registered.

Histidine decarboxylase deficiency inhibits NBP-induced extramedullary hematopoiesis by modifying bone marrow and spleen microenvironments.

Histidine decarboxylase (HDC), a histamine synthase, is expressed in various hematopoietic cells and is induced by hematopoietic cytokines such as granulocyte colony-stimulating factor (G-CSF). We previously showed that nitrogen-containing bisphosphonate (NBP)-treatment induces extramedullary hematopoiesis via G-CSF stimulation. However, the function of HDC in NBP-induced medullary and extramedullary hematopoiesis remains unclear. Here, we investigated changes in hematopoiesis in wild-type and HDC-deficient (HDC-KO) mice. NBP treatment did not induce anemia in wild-type or HDC-KO mice, but did produce a gradual increase in serum G-CSF levels in wild-type mice. NBP treatment also enhanced Hdc mRNA expression and erythropoiesis in the spleen and reduced erythropoiesis in bone marrow and the number of vascular adhesion molecule 1 (VCAM-1)-positive macrophages in wild-type mice, as well as increased the levels of hematopoietic progenitor cells and proliferating cells in the spleen and enhanced expression of bone morphogenetic protein 4 (Bmp4), CXC chemokine ligand 12 (Cxcl12), and hypoxia inducible factor 1 (Hif1) in the spleen. However, such changes were not observed in HDC-KO mice. These results suggest that histamine may affect hematopoietic microenvironments of the bone marrow and spleen by changing hematopoiesis-related factors in NBP-induced extramedullary hematopoiesis.

MiR-375 Impairs the Invasive Capabilities of Hepatoma Cells by Targeting HIF1α Under Hypoxia.

BACKGROUND AND AIMS: Hypoxia represents one of the most pervasive microenvironmental stresses in HCC due to the overwhelming growth and inadequate blood supply. HIF1α as an important transcription factor participates in the regulation of various biological behaviors of HCC cells under hypoxia. Our previous study indicated that miR-375 is a hypoxia-associated miRNA. However, the interaction between miR-375 and HIF1α remains unclear. METHODS: Bioinformatic analysis was performed for miRNA screening. qRT-PCR, western blotting, and immunohistochemical staining were used to detect the expression of related molecules. Bioinformatic analysis and dual luciferase assay were used to predict and further confirm the target association. Transwell chamber assay and flow cytometry were, respectively, used to detect migration, invasion and apoptosis of hepatoma cells. RESULTS: MiR-375 presented an obviously differential expression in human HCCs versus background livers (BLs) and HCCs versus normal liver tissues (NLTs). In rat models, miR-375 was gradually declined during hepatocarcinogenesis. HIF1α was remarkably upregulated at protein level rather than at mRNA level in human HCCs versus BLs, HCCs versus NLTs, BLs versus NLTs, and in rat fibrotic livers versus NLTs. HIF1α was determined to be a target of miR-375. MiR-375 inhibitor induced the migration and invasive capabilities and attenuated apoptosis of hepatoma cells under hypoxia. Depriving HIF1α by siRNA could partially reverse the function of miR-375 inhibitor under hypoxia. CONCLUSIONS: MiR-375 impairs the invasive capabilities of HCC cells by targeting HIF1α under hypoxia.

Hypoxia contributes to galectin-3 expression in renal carcinoma cells.

Galectin-3 is supposed as a prognostic factor and therapeutic target for many cancers. In a previous study, we have reported that galectin-3 was related to the development of renal cell cancer and served a therapeutic target for renal cell carcinoma (RCC). However, the mechanisms underlying the regulation of galectin-3 in RCC are still not known. In this study, we detected the expression of galectin-3 and hypoxia-inducible factor 1 (HIF-1) α in RCC using immunohistochemistry, and then conducted in vitro experiments to verify the regulation of galectin-3 by hypoxia in RCC. Our results showed that the expression of galectin-3 and HIF-1α were remarkably high in RCC tissues compared with those in the paracancerous tissues. Interestingly, hypoxia significantly promoted cytoplasmic and nuclear HIF-1α and galectin-3 expression in renal carcinoma cell lines, but not in renal tubular epithelial cell (HK-2). Renal carcinoma cell line (Caki-1), but not HK-2 showed significant increase of luciferase reporter activity of galectin-3 encoding the fragment from the site of -845 to +50 upon hypoxic insult. Moreover, HIF-1α overexpression vector promoted, while HIF-1α silencing vector reduced luciferase reporter activity of galectin-3 in Caki-1 and HK-2 cells in both normal and hypoxia conditions. A direct interaction of HIF-1α with Gal-3 promoter was also verified by electrophoretic mobility shift assay and chromatin immunoprecipitation. Together, our data indicated that hypoxia was critical for galectin-3 expression in RCC in a HIF-1α-dependent manner.

The Expression and Role of Hypoxia-induced Factor-1α in Human Tenon's Capsule Fibroblasts under Hypoxia.

PURPOSE: To determine the expression of hypoxia-induced factor-1α (HIF-1α) and its downstream factors in human Tenon's capsule fibroblasts (HTFs) and changes in HTFs biological functions, we explored the role of HIF-1α in HTFs under hypoxia to provide a basis for studying the regulation of HIF-1α in wound healing after glaucoma surgery. MATERIALS AND METHODS: we established HTFs hypoxia model in vitro, meanwhile the HIF-1α agonist VH298 or inhibitor KC7F2 was added to HTFs, and the normoxia group was used as a control. Western blot, immunofluorescence and ELISA were used to detect the expression of HIF-1α, vascular endothelial growth factor (VEGF), transforming growth factor-ß (TGF-ß), Smads and collagen I. The proliferation of HTFs was quantified by cell counting kit-8, and cell migration was tested by healing scratch test. RESULTS: HIF-1α protein expression increased under hypoxia, peaked from 4-24 h, and then decreased. The secretion of VEGF and TGF-ß increased with prolonged hypoxia time. VH298 and KC7F2 upregulated and downregulated the levels of VEGF and TGF-ß, respectively, suggesting that HIF-1α upregulates and downregulates the levels of VEGF and TGF-ß in HTFs under hypoxia, respectively. HIF-1α upregulated the proliferation, migration and collagen synthesis of HTFs under hypoxia. CONCLUSIONS: Regulating HIF-1α and its downstream factors effectively regulated HTFs proliferation, migration and collagen synthesis. HIF-1α is a promising regulator in the study of wound healing after glaucoma surgery.

FDG PET correlates weakly with HIF-1α expression in solid tumors: a meta-analysis.

BACKGROUND: Hypoxia-inducible factor (HIF)-1α plays a key role in hypoxic adaptation of tumor cells. Overexpression of HIF-1α is associated with tumor aggressiveness and worse prognosis in several malignancies. Presumably, expression of HIF-1a may be reflected by positron emission tomography with 2-deoxy-2 [fluorine-18] fluoro-D-glucose (18F-FDG PET). There are inconsistent data about relationships between FDG PET and HIF-1α. PURPOSE: To provide evident data about associations between maximum standardized uptake value (SUVmax) and HIF-1α expression in solid tumors. MATERIAL AND METHODS: MEDLINE, SCOPUS, and EMBASE databases were screened for relationships between SUV and HIF-1α up to August 2019. Overall, 21 studies with 1154 patients were identified. The following data were extracted from the literature: authors; year of publication; number of patients; and correlation coefficients. RESULTS: Correlation coefficients between SUVmax and HIF-1α were in the range of -0.51-0.71. The pooled correlation coefficient was 0.27 (95% confidence interval [CI] = 0.14-0.41). Furthermore, correlation coefficients for some tumor entities were calculated. For this sub-analysis, data for primary tumors with >2 reports were included. The calculated correlation coefficients in the analyzed subgroups were as follows: head and neck squamous cell carcinoma: ρ = 0.25 (95% CI = 0.07-0.42); non-small lung cell cancer: ρ = 0.27 (95% CI = -0.14-0.67); uterine cervical cancer: ρ = -0.09 (95% CI = -0.89-0.71); thymic tumors: ρ = 0.39 (95% CI = 0.04-0.58). CONCLUSION: SUVmax of FDG PET correlated weakly with expression of HIF-1α both in overall sample and tumor subgroups. Therefore, FDG PET cannot be used for prediction of hypoxia in clinical practice.