Hypoxia Reoxygenation Condition Research Articles

Forkhead transcription factor FOXO1 is involved in hypoxia/reoxygenation-induced gonadotropin-releasing hormone decline.

Previously, it has been demonstrated that aging is associated with nuclear factor-κB (NF-κB)-mediated hypothalamic gonadotropin-releasing hormone (GnRH) decrease. The hypothalamus is one of the brain regions that are vulnerable to ischemia-reperfusion injury. However, it is unclear whether ischemia-reperfusion has an influence on the hypothalamic GnRH release. In the current study, GT1-7 cells, which are a cell line of hypothalamic GnRH neurons, were subjected to hypoxia-reoxygenation to mimic ischemia-reperfusion. The effect of hypoxia-reoxygenation on the hypothalamic GnRH release was investigated. It was found that GnRH secretion from GT1-7 cells was decreased under the hypoxia-reoxygenation condition. Mechanistic studies revealed that hypoxia-reoxygenation activated nuclear factor-κB (NF-κB) via the protein kinase B (Akt)/forkhead box protein O1 (FOXO1) pathway, thereby inhibiting gnrh1 gene. The results of the current study suggested that hypoxia-reoxygenation injury may facilitate the hypothalamic programming of system aging through impairment of hypothalamic GnRH release.

Pre-ischemic renal lavage protects against renal ischemia-reperfusion injury by attenuation of local and systemic inflammatory responses.

Postischemic acute kidney injury (AKI) is a common clinical complication and often fatal, with no effective treatment available. Little is known about the role of leukocytes trapped in renal vessels during ischemia-reperfusion injury (IRI) in the postischemic AKI. We designed a new animal model in rats with preforming renal artery lavage prior to IRI to investigate the effect of diminishing the residual circulating leukocytes on kidney damage and inflammation. Moreover, the functional changes of macrophages in hypoxia reoxygenation condition were also analyzed. We found pre-ischemic renal lavage significantly decreased the serum creatinine and blood urea nitrogen levels, and downregulated the mRNA and protein expressions in kidneys and urinary secretion of kidney injury molecule-1 of rats after IRI. The renal pathological damage caused by IRI was also ameliorated by pre-ischemic renal lavage, as evidenced by fewer cast formation, diminished morphological signs of AKI in the tissue at 24hours after IRI. Pre-ischemic renal lavage reduced the numbers of infiltrating CD68+ macrophages and MPO+ neutrophils. The mRNA expression of pro-inflammatory mediator in IRI kidneys and the levels of pro-inflammatory cytokines in circulatory system and urine were also reduced due to pre-ischemic lavage. Compared with nontreated rats with IRI, pre-ischemic renal lavage significantly reduced the phosphorylation levels of ERK and p65 subunit of NF-κB in the kidney after IRI. In addition, we found hypoxia/reoxygenation could promote the expression of pro-inflammatory mediators and inhibit the expression of anti-inflammatory factors by regulating ERK/NF-κB signaling pathway. Thus, pre-ischemic renal lavage could clearly reduce the renal damage after IRI by attenuating inflammation, and macrophages trapped in renal vessels during IRI could be important pathogenic factors driving tissue injury.

Downregulated N-acetylglucosaminyltransferase III is involved in attenuating trophoblast migration and invasion under hypoxia–reoxygenation condition

Objective: Many studies have confirmed that N-acetylglucosaminyltransferase III (GnT-III) is correlated with tumor invasion and metastasis. However, the expression of GnT-III and its role in normal pregnancy and preeclampsia (PE) has not been reached. So the primary objective of this study is to determine GnT-III expression in normal pregnancy and whether its expression is vulnerable to oxidative stress in the trophoblast cells.Methods: Human first trimester villous tissues from normal pregnancies and third trimester placentas from pregnancies with or without preeclampsia (PE) were used for the detection of GnT-III expression. Human first trimester extravillous trophoblast cell line (HTR8/SVneo) exposed to hypoxia/reoxygenation (H/R) condition was employed as an oxidative stress model in vitro to investigate the expression of GnT-III.Results: GnT-III was strongly expressed in cytotrophoblast (CTBs), syncytiotrophoblast (STBs) and the trophoblast columns (TCs) of human placental villi, and decidual cells in the maternal decidua. The expression of GnT-III was decreased in PE placentas compared with the normal control placentas. In addition, GnT-III was found to have decreased expression in H/R-exposed HTR8/SVneo cells, and the invasive and migratory abilities of HTR8/SVneo cells were attenuated, too.Conclusions: These findings suggest that GnT-III is an important regulator at the maternal-fetal interface during early pregnancy. Excessive oxidative stress can decrease GnT-III expression in trophoblast and the decreased expression of GnT-III may be involved in the development of preeclampsia.

Viability of osteoblasts under cell hypoxia condition

Objective: To investigate the effects of hypoxia condition and hypoxia-reoxygenation condition on the cell viability, apoptosis rate and gene expression of osteoblasts cultured in vitro. Methods: The cranium osteoblasts from newborn Sprague Dawley rats within 48 hours were cultured and purified through tissue block method.The morphological changes of cells were evaluated by the Alizarin Red S staining and Alkaline phosphatase staining.The third-generation osteoblasts were cultured in normal condition for 36 hours (group A), in hypoxic condition for 24hours (group B), in hypoxic condition for 24hours thereafter reoxygenated for 12 hours (group D), in hypoxic condition for 36 hours (group C). The cell viability of osteoblasts was tested via MTT assay.The apoptosis rate of osteoblasts was tested by FCM (flow cytometry). Quantitative PCR and Western blot methods were used to determine Collagen type Ⅰ, Bone morphogenetic protein 2 (BMP-2), Runt-related transcription factor 2 (RUNX-2), Transforming growth factor-β1(TGF-β1) expression levels. Results: The cell viability of osteoblasts decreased, group A(99.1%±8.3%), group B(90.9%±9.4%), group C(79.9%±8.7%), group D(73.0%±8.2%), group D <group C <group B <group A (F=37.886, P=0.000); the apoptosis rate of osteoblasts increased, group A(1.9%±1.3%), group B(16.3%±2.5%), group C(28.2%±4.2%), group D(33.5%±3.6%), group D >group C >group B >group A(F=26.198, P=0.000); the mRNA expressions of Col Ⅰ, BMP-2, RUNX-2, TGF-β1 decreased under hypoxia and hypoxia-reoxygenation condition, and group D< group C< group B< group A (F=13.082, P=0.006; F=7.088, P=0.017; F=6.857, P=0.038; F=51.368, P=0.000); the protein expressions of Col Ⅰ, BMP-2, RUNX-2, TGF-β1 decreased under hypoxia and hypoxia-reoxygenation condition, and group D< group C< group B< group A (F=8.114, P=0.013; F=28.935, P=0.000; F=9.857, P=0.007; F=46.541, P=0.000). Conclusion: Hypoxia condition and hypoxia-reoxygenation condition decreased the cell viability, increase the apoptosis rate and suppress the expressions of associated genes.Hypoxia-reoxygenation condition aggravate the injure of osteoblasts preconditioning under hypoxia condition.

Expression and significance of SATB1 and wnt/β-catenin signaling molecule in the placenta of preeclampsia

To explore the role of specific AT rich sequence binding protein 1(SATB1) and wnt/β-catenin signaling pathways in the regulation of trophoblast invasion and its effect in the pathogenesis of preeclampsia. From March 2013 to March 2014, 20 cases of human villous tissues (early pregnancy group) from women of 8-10 gestational weeks who received artificial abortion at the First Affiliated Hospital of Chongqing Medical University, 18 cases of placental tissues (mid-pregnancy group) from women of 18-20 gestational weeks who had labor induction by water bag, 20 cases of placental tissues (normal full-term group) from healthy full-term pregnancy women and 20 cases of placental tissues (preeclamptic group) from women with preeclampsia who received elective c-section in were collected. Immunohistochemical SP method was utilized to determine the position of SATB1 and beta-catenin in villous tissues or placental tissues. Western blot was performed to analyze the expression level of SATB1 and beta-catenin in villous tissues or placental tissues. Immunofluorescence assay was used to determine the location of SATB1 and β-catenin in HTR8/SVneo cells. Western blot was performed to detect the expression level of SATB1 and beta-catenin in HTR8/SVneo cells cultured in normoxia and hypoxia reoxygenation (H/R) condition. Co-Immunoprecipitation detection was used to evaluate the interaction between SATB1 and β-catenin in placental tissues in preeclamptic group and HTR8/SVneo cells in H/R group. Gelatin zymography analysis was used to measure the activity of matrix metalloproteinases (MMP)-2 and 9 in placental tissues from preeclamptic group and HTR8/SVneo cells in H/R group. (1) In the normal full-term group, rare syncytiotrophoblastic nodule, less fibrinoid necrosis and abundant numbers of capillary could be observed in placental tissues. In comparison, there were obvious vacuolation in the cytoblast of syncytiotrophoblast, rich fibrinoid necrosis and poor numbers of villous capillary in placental tissues from preeclamptic group. (2) SATB1 could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of SATB1 were more weakening in preeclamptic group than in the normal full-term group. (3) β-catenin could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of β-catenin were more weakening in preeclamptic group than in the normal full-term group. (4) The protein expression levels of SATB1 in early pregnancy group, mid-pregnancy group, normal full-term group and preeclamptic group were 0.300 ± 0.009, 0.271±0.015, 0.238±0.018 and 0.153±0.007, respectively. The protein levels of β-catenin among the above groups were 0.743±0.041, 0.648±0.021, 0.549±0.069 and 0.269±0.047, respectively. Both the expression of SATB1 and β-catenin protein were significant decreased in placental tissues from preeclamptic group compared with the other three groups. (5) The SATB1 and β-catenin protein was located in nucleus of trophoblast and a small amount was in the cytoplasm. The fluorescence intensity of both SATB1 and β-catenin in the H/R group were significantly decreasing when compared to the normoxia group. (6) HTR8/SVneo cells in H/R group showed a significant decrease in both SATB1 and β-catenin protein levels when compared to the normoxia group. The protein level of SATB1 in the normoxia group was 0.213±0.005, while was 0.083±0.021 in the H/R group. The protein level of β-catenin in the normoxia group was 0.797±0.081, and was 0.543±0.131 in the H/R group. (7) There was an interaction between SATB1 and β-catenin in placental tissues from the preeclamptic group and HTR8/SVneo cells exposed by H/R. (8) The enzymatic activity of MMP-2 and MMP-9 protein were decreased significantly in placental tissues from the preeclamptic group (2.251±0.310, 1.447±0.102, respectively) when compared to the normal full-term group (7.098±0.451, 5.502±0.197, respectively). MMP-2 and MMP-9 were significantly decreased in the H/R group (0.471±0.104, 0.297±0.103, respectively) when compared to the normoxia group (0.842±0.209, 0.595±0.100, respectively). The expression of SATB1 decreased in the placenta of preeclampsia. This may influence the activity of MMP-2 and 9 by regulating Wnt/β-catenin signaling pathways, affect trophoblast invasion and eventually result in preeclampsia.

Effects of Remifentanil Preconditioning on Osteoblasts under Hypoxia-Reoxygenation Condition.

Background: Ischemia-reperfusion of bone occurs in a variety of clinical conditions, such as orthopedic arthroplasty, plastic gnathoplasty, spinal surgery, and amputation. Usually, cellular models of hypoxia-reoxygenation reflect in vivo models of ischemia-reperfusion. With respect to hypoxia-reoxygenation conditions, the effects of remifentanil on osteogenesis have received little attention. Therefore, we investigated the effects of remifentanil on the proliferation and differentiation of osteoblasts during hypoxic-reoxygenation.Methods: After remifentanil (0.1, 1 ng/mL) preconditioning for 2 hours, human osteoblasts were cultured under 1% oxygen tension for 24 hours. Thereafter, the cells were reoxygenated for 12 hours at 37 °C. The naloxone groups were treated with naloxone for 30 minutes before remifentanil treatment. We measured cell viability via MTT assay. Osteoblast maturation was determined by assay of bone nodular mineralization. Quantitative PCR and western blot methods were used to determine BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 expression levels.Results: Osteoblast viability and bone nodular mineralization by osteoblasts is recovered by remifentanil preconditioning from hypoxia-reoxygenation insult. During hypoxic-reoxygenation condition, remifentanil preconditioning induced the expression of BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 in osteoblasts.Conclusions: Under hypoxia-reoxygenation conditions, remifentanil preconditioning enhanced the cell viability and maturation of osteoblasts, and stimulated the expression of proteins associated with osteoblast proliferation and differentiation of the osteoblast. Our results suggest that remifentanil may help in the treatment of bone stress injuries.

Effects of platelets on the adhesion between leukocytes and liver sinusoidal endothelium cells as well as on the transendothelial migration of leukocytes undergoing hypoxia-reoxygenation

To investigate the effects of platelet on intercellular adhesion between leukocyte and liver sinusoidal endothelial cell(LSEC) and the transendothelial migration under the hypoxia-reoxygenation condition, as well as the role of relevant adhesion molecules. LSEC was cultured for 24 hours under hypoxia condition and then reoxygenated for 2 hours (hypoxia-reoxygenation, HR). This hypoxia-reoxygenation model was used to simulate the clinical liver ischemia-reperfusion injury process (IRI). Platelets and leukocytes were labeled with fluorescence dye, and then the adhesion was detected by fluorescence microscope, fluorescence plate reader and laser scanning confocal microscope. Antibody blockage experiment was used to analyze the relevant adhesion molecules. The adhesion between platelets and LSEC was increased significantly after HR. The fluorescence intensity of adherent platelets increased from 142.10 ± 7.53 to 289.17 ± 20.00(P < 0.01). After H-R treatment and the addition of platelets, the number of adherent leukocytes increased markedly, and a significant statistical difference (360.71 ± 23.47 and 186.39 ± 17.96, P < 0.01) was found in comparing with the platelet deficient group. These adhesion processes could be blocked respectively by anti-GPIb, anti-GPIIb, anti-GPIIIa, anti-P-selectin, anti-CD31, anti-ICAM-1, anti-VCAM-1 and anti-ELAM-1. Confocal microscopy showed that platelets located between leukocytes and LSEC, and mediated their adhesion process. However, the adhesion of platelets to LSEC decreased the transendothelial migration of leukocytes (227.79 ± 16.51 and 167.27 ± 10.92, P < 0.05). During ischemia-reperfusion condition platelets adhere to the surface of LSEC, and then further mediate more adhesion processes between leukocytes and endothelial cells, as well as inhibit the transendothelial migration of leukocytes. The consequence is that large numbers of leukocytes were sequestrated within hepatic sinus, and deteriorate liver ischemia-reperfusion injury.

Platelet adhesion and fusion to endothelial cell facilitate the metastasis of tumor cell in hypoxia-reoxygenation condition

To investigate the relevant molecular mechanisms of platelet in promoting metastasis of tumor cell. The adhesion of fluorescence dye labeled-platelet to human liver sinusoidal endothelial cell (LSEC) line and tumor cell lines were detected by fluorescence microscope and fluorescence plate reader or laser scanning confocal microscope. The relevant adhesion molecules were analyzed by the antibody blockage experiment. The immune colloidal gold transmission electron microscope (TEM), flow cytometry and dye transfer were used to decipher the adhesion and fusion of platelet and LSEC. The tumor cells adhesion to vessels in ischemia condition was analyzed on mouse mesenteric vessels and the metastasis and neovascularization of metastatic foci in pulmonary tissue were also detected after tumor cells injected into nude mice via tail veil. After hypoxia-reoxygenation, tumor cell or LSEC markedly increased its adhesion with platelet, which could be blocked by different antibodies to platelet adhesion molecules. Platelet increased adhesion of tumor cell to LSEC in dose-dependent manner. The fusion of platelet and LSEC was demonstrated by translocation of fluorescent dye from platelet into the adherent LSEC; gpIIb emerged on the LSEC; and confirmed by TEM. The morphological examination found platelet presented between tumor cell and LSEC. Animal experiment indicated that the tumor adhesion to vessels was seldom in normal condition, but increased in ischemia-reperfusion condition, and further significantly enhanced by platelets. The number of tumor metastatic foci and the density of blood vessels within metastatic foci in lung were markedly increased by tumor cell pre-adhered with platelet. The adhesion or fusion of platelet to endothelial cell mediated by platelet surface adhesion molecules, which could promote the adhesion of tumor cell with endothelial cells and the tumor metastasis.