Oxygen Tension in the Bone Marrow (BM) of Patients with Malignant and Indolent Monoclonal Gammopathy: Role of Hypoxia and Hypoxia-Inducible Factor (HIF)-1α in the Regulation of Gene Expression and Pro-Angiogenic Profiles of CD138+ Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 422-422 ◽  
Author(s):  
Nicola Giuliani ◽  
Simona Colla ◽  
Paola Storti ◽  
Valentina Sgobba ◽  
Katia Todoerti ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Bone Marrow ◽  
Monoclonal Gammopathy ◽  
Hypoxia Inducible Factor ◽  
Heme Oxygenase 1 ◽  
Protein Ubiquitination ◽  
Significant Difference ◽  
Bone Biopsies

Abstract Abstract 422 Multiple myeloma (MM) is characterized by the accumulation of malignant plasmacells into the bone marrow (BM) microenvironment that supports their growth and survival. Particularly, an increase of BM angiogenesis occurs in relationship with plasmacells infiltration playing a critical role in the progression on monoclonal gammopathy. Hypoxia is known to be associated to angiogenesis in solid tumors as well as the hypoxia-inducible factor (HIF)-1α is a critical trigger and regulator of the angiogenic switch. Actually, the oxygen levels in the BM of patients with monoclonal gammopathy as well the effects of hypoxia and HIF-1α on the gene expression and pro-angiogenic profile of CD138+ cells are not known. In this study, first, we investigated the level of BM oxygen saturation (sO2) and partial pressure (pO2) in a cohort of 44 patients with monoclonal gammopathy at the diagnosis including active MM (n°=25), smoldering MM (n° = 8) and MGUS (n°=11) showing that BM of MM patients was hypoxic (mean ± SD of pO2: 52.5 ± 8.69 mmHg; sO2 of 83.7 ± 11%) even if any significant difference in both pO2 and sO2 was not observed in comparison with smoldering MM patients or MGUS as well as in relationship with the stage of disease (p=0.7). Next, we evaluated how hypoxia exposition could modify the gene expression profile of CD138+cells isolated form MM patients by U133 Plus2.0 Arrays. By supervised analysis performed on 11 paired samples we found that hypoxia significantly modulated 714 genes in CD138+ cells isolated from MM patients. Interestingly, genes belonging either to oxidative stress and hypoxia signaling, including heme oxygenase 1 (HMOX1) and the heat shock proteins 90kDa alpha (HSP90AA1; HSP90AB1), or to protein ubiquitination pathway, such as XIAP, were significantly up-regulated by hypoxia. Among the pro-angiogenic genes, we found that both VEGFA and IL8 were induced by hypoxia. Following, given that HIF-1α accumulates only in hypoxic condition, we checked HIF-1α protein expression in the BM of MM patients by immunohistochemistry on bone biopsies immediately after fixation. A strong HIF-1α immunostaining was demonstrated in MM cells at nuclear level in all patients analyzed. Interestingly, the presence of HIF-1α protein was also observed in isolated CD138+ MM cells of about 28% of MM patients in normoxic condition. In order to investigate the potential role of HIF-1α on MM cell gene expression and angiogenic profile we performed HIF-1α silencing in MM cells by siRNA anti-HIF-1α and that exposed cells to normoxic or hypoxic conditions. HIF-1α suppression was associated to the modulation of pro-angiogenic molecules (VEGFA, VEGFB, IL-8 and PGF) and oxidative stress (SOD2, PTGS2, TXT) and glycogenolysis regulating (ENO2, ALDOC, PFKFB3, HK2, PDK1, PFKFB4) genes. Data obtained were than validated by real time PCR and at protein level by western blot and ELISA assay. Consistently we found that HIF-1α suppression significantly inhibited the pro-angiogenic properties, evaluated in an in vitro angiogenesis model as capillary junctions and tubules formation and tubule length. In conclusion, we demonstrate that the MM-BM environment is hypoxic and that HIF-1α protein expressed by MM cells. Consistently we show that hypoxia and HIF-1α significantly modulate the gene expression profiles of MM cells regulating the expression of the pro-angiogenic factors by MM cells and their pro-angiogenic properties. Disclosures: No relevant conflicts of interest to declare.

Hypoxia and Hypoxia Inducible Factor (HIF)-1α in Multiple Myeloma: Effect on the Pro-Angiogenic Signature of Myeloma Cells and the Bone Marrow Microenvironment.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1687-1687
Author(s):  
Simona Colla ◽  
Paola Storti ◽  
Gaetano Donofrio ◽  
Mirca Lazzaretti ◽  
Sabrina Bonomini ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Oxygen Tension ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Signal Pathways ◽  
Normoxic Condition ◽  
Nuclear Level ◽  
Bone Biopsies

Abstract Hypoxia is a common feature of solid tumors associated to angiogenesis and malignant phenotype. Tumor adaptation to hypoxia is mainly due to the hypoxia-inducible factor (HIF)-1α, a key transcription factor that regulates angiogenesis and tumor progression. As known multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of malignant plasmacells into a hypoxic microenvironment as the bone marrow (BM) that critically supports their growth and survival. However the effect of hypoxia on MM cells and the role of HIF-1α in MM-induced angiogenesis actually are not known. Recently we have demonstrated that the tumor suppressor gene ING4 may exert an anti-angiogenic effect through the inhibition of HIF-1α activity in MM cells in hypoxic condition suggesting a role of HIF-1α in MM-induced angiogenic switch. To go further insight this issue, in this study, first we checked the level of BM oxygen tension in a cohort of MM patients (n°=25) at the diagnosis as compared to healthy donors and MGUS subjects. The mean pO2 ± SD was 52.3±9 mmHg (p=NS) in MM patients similar to that observed in the controls, confirming that MM cells are exposed in vivo to hypoxic microenvironment. Thereafter HIF-1α protein expression by MM cells was checked by immunohistochemistry on bone biopsies showing the presence of HIF-1α stabilization at nuclear level in malignant plasmacells as well as in BM stromal cells (BMSC) into the BM. Consequently the effect of hypoxia and HIF-1α in both MM and BMSC cells was checked. Human myeloma cell lines (JJN3 and RPMI-8226) and BMSC were transfected with a pool of siRNA anti-HIF-1α to knockout HIF-1α and then exposed to low oxygen tension. A gene expression profiling evaluation was performed by microarray analysis using Gene Chips U133plus 2.0 (Affymetrix). Data were then validated by real time PCR. We found that hypoxia significantly upregulated the expression of the pro-angiogenic molecules in both MM and BMSC cells including Vascular Endothelial Growth Factor (VEGF), Osteopontin (OPN) and Interleukin-8 (IL-8) blunted by siRNA anti-HIF-1α. Genes belonging to glycolysis and HIF-1α regulating signal pathways were found to be also regulated by HIF-1α in MM cells in hypoxic condition. These observations were confirmed in purified CD138+ MM cells (n°=11) exposed to hypoxia that induced a significant up-regulation of the pro-angiogenic molecules and the modulation of glycolysis and ubiquitin mediated proteolysis signal pathways. Finally, the potential expression and role of HIF-1α in MM cells was also investigated in normoxic condition. Whereas the presence of HIF-1α mRNA was observed in all HMCLs and primary MM cells tested, HIF-1a protein stabilization and activity was observed at nuclear level in 2 out of 6 HMCLs and in about 38% of MM patients evaluated suggesting that a hypoxia independent stabilization of HIF-1α may occur in MM cells. Consistently, in normoxic condition, HIF-1α knock out by siRNA significantly affected in HMCLs either pro-angiogenic molecules as VEGF or several genes belonging to cell cycle regulation. In conclusion our data underline the role of hypoxia in the regulation of the angiogenic signature of MM cells and the BM microenvironment and suggest that HIF-1α could be a potential target in MM.

Abstract 545: Redox-Sensitive Regulation of Bone Marrow Hematopoietic Progenitor Cells

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Shi Pan ◽  
Nadan Wang ◽  
Shey-Shing Sheu
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
Progenitor Cells ◽  
Blood Cells ◽  
Bone Marrow Failure ◽  
Hematopoietic Progenitor Cells ◽  
Wild Type ◽  
Hematopoietic Progenitor ◽  
Significant Difference

Bone marrow failure is a group of hematopoietic stem cell disorders that affect one or more lineages of blood cells. Hematopoietic progenitor cells are highly sensitive to reactive oxygen species (ROS)-induced oxidative stress. ROS impair the self-renewal of hematopoietic progenitor cells in the bone marrow and cause bone marrow failure. Glutaredoxin (Grx) is an antioxidant enzyme important for many cellular processes such as resistance against oxidative stress, DNA synthesis, sulfur assimilation, apoptosis, and cellular differentiation. However, the role of Grx in hematopoietic progenitor cells remains unknown. We study the role of Grx in hematopoietic progenitor cells using Grx KO mice as the model system. Bone marrow cells were isolated from 9-10 weeks old wild type and Grx KO mice and the ratio of KSL cells, total blood count and p38 activation was studied. Our results showed no significant difference on the ratio of KSL cells between wild type and Grx KO mice in basal condition. There is also no significant difference in the numbers of red blood cells, lymphocytes, white blood cells and platelet in basal condition between wild type mice and Grx KO. Interestingly, upon hydrogen peroxide treatment, there is higher level of p38 activation in Grx KO mice compared to wild type mice. Our results suggest that Grx is involved in redox-sensitive regulation of hematopoietic progenitor cells. Grx may play a regulatory role in the prevention of bone marrow failure.

scholarly journals Red Yeast Rice Protects Circulating Bone Marrow-Derived Proangiogenic Cells against High-Glucose-Induced Senescence and Oxidative Stress: The Role of Heme Oxygenase-1

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Jung-Tung Liu ◽  
Huey-Yi Chen ◽  
Wen-Chi Chen ◽  
Kee-Ming Man ◽  
Yung-Hsiang Chen
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
Heme Oxygenase ◽  
High Glucose ◽  
Protoporphyrin Ix ◽  
Vascular Complications ◽  
Heme Oxygenase 1 ◽  
Red Yeast Rice ◽  
And Oxidative Stress

The inflammation and oxidative stress of bone marrow-derived proangiogenic cells (PACs), also named endothelial progenitor cells, triggered by hyperglycemia contributes significantly to vascular dysfunction. There is supporting evidence that the consumption of red yeast rice (RYR; Monascus purpureus-fermented rice) reduces the vascular complications of diabetes; however, the underlying mechanism remains unclear. This study aimed to elucidate the effects of RYR extract in PACs, focusing particularly on the role of a potent antioxidative enzyme, heme oxygenase-1 (HO-1). We found that treatment with RYR extract induced nuclear factor erythroid-2-related factor nuclear translocation and HO-1 mRNA and protein levels in PACs. RYR extract inhibited high-glucose-induced (30 mM) PAC senescence and the development of reactive oxygen species (ROS) in a dose-dependent manner. The HO-1 inducer cobalt protoporphyrin IX also decreased high-glucose-induced cell senescence and oxidative stress, whereas the HO-1 enzyme inhibitor zinc protoporphyrin IX and HO-1 small interfering RNA significantly reversed RYR extract-caused inhibition of senescence and reduction of oxidative stress in high-glucose-treated PACs. These results suggest that RYR extract serves as alternative and complementary medicine in the treatment of these diseases, by inducing HO-1, thereby decreasing the vascular complications of diabetes.

scholarly journals MicroRNA treatment modulates osteogenic differentiation potential of mesenchymal stem cells derived from human chorion and placenta

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kulisara Marupanthorn ◽  
Chairat Tantrawatpan ◽  
Pakpoom Kheolamai ◽  
Duangrat Tantikanlayaporn ◽  
Sirikul Manochantr
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Transcription Factor ◽  
Osteogenic Differentiation ◽  
Differentiation Potential ◽  
Osteogenic Gene Expression ◽  
Osteogenic Gene

AbstractMesenchymal stem cells (MSCs) are important in regenerative medicine because of their potential for multi-differentiation. Bone marrow, chorion and placenta have all been suggested as potential sources for clinical application. However, the osteogenic differentiation potential of MSCs derived from chorion or placenta is not very efficient. Bone morphogenetic protein-2 (BMP-2) plays an important role in bone development. Its effect on osteogenic augmentation has been addressed in several studies. Recent studies have also shown a relationship between miRNAs and osteogenesis. We hypothesized that miRNAs targeted to Runt-related transcription factor 2 (Runx-2), a major transcription factor of osteogenesis, are responsible for regulating the differentiation of MSCs into osteoblasts. This study examines the effect of BMP-2 on the osteogenic differentiation of MSCs isolated from chorion and placenta in comparison to bone marrow-derived MSCs and investigates the role of miRNAs in the osteogenic differentiation of MSCs from these sources. MSCs were isolated from human bone marrow, chorion and placenta. The osteogenic differentiation potential after BMP-2 treatment was examined using ALP staining, ALP activity assay, and osteogenic gene expression. Candidate miRNAs were selected and their expression levels during osteoblastic differentiation were examined using real-time RT-PCR. The role of these miRNAs in osteogenesis was investigated by transfection with specific miRNA inhibitors. The level of osteogenic differentiation was monitored after anti-miRNA treatment. MSCs isolated from chorion and placenta exhibited self-renewal capacity and multi-lineage differentiation potential similar to MSCs isolated from bone marrow. BMP-2 treated MSCs showed higher ALP levels and osteogenic gene expression compared to untreated MSCs. All investigated miRNAs (miR-31, miR-106a and miR148) were consistently downregulated during the process of osteogenic differentiation. After treatment with miRNA inhibitors, ALP activity and osteogenic gene expression increased over the time of osteogenic differentiation. BMP-2 has a positive effect on osteogenic differentiation of chorion- and placenta-derived MSCs. The inhibition of specific miRNAs enhanced the osteogenic differentiation capacity of various MSCs in culture and this strategy might be used to promote bone regeneration. However, further in vivo experiments are required to assess the validity of this approach.

scholarly journals Effects of Nrf2 Deficiency on Bone Microarchitecture in an Experimental Model of Osteoporosis

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Lidia Ibáñez ◽  
María Luisa Ferrándiz ◽  
Rita Brines ◽  
David Guede ◽  
Antonio Cuadrado ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
Bone Metabolism ◽  
Bone Microarchitecture ◽  
Related Factor ◽  
Mineral Density ◽  
Trabecular Bone Mineral Density ◽  
Bone Marrow Derived Cells

Objective. Redox imbalance contributes to bone fragility. We have evaluated the in vivo role of nuclear factor erythroid derived 2-related factor-2 (Nrf2), an important regulator of cellular responses to oxidative stress, in bone metabolism using a model of postmenopausal osteoporosis.Methods. Ovariectomy was performed in both wild-type and mice deficient in Nrf2 (Nrf2−/−). Bone microarchitecture was analyzed byμCT. Serum markers of bone metabolism were also measured. Reactive oxygen species production was determined using dihydrorhodamine 123.Results. Sham-operated or ovariectomized Nrf2−/−mice exhibit a loss in trabecular bone mineral density in femur, accompanied by a reduction in cortical area in vertebrae. Nrf2 deficiency tended to increase osteoblastic markers and significantly enhanced osteoclastic markers in sham-operated animals indicating an increased bone turnover with a main effect on bone resorption. We have also shown an increased production of oxidative stress in bone marrow-derived cells from sham-operated or ovariectomized Nrf2−/−mice and a higher responsiveness of bone marrow-derived cells to osteoclastogenic stimuli in vitro.Conclusion. We have demonstrated in vivo a key role of Nrf2 in the maintenance of bone microarchitecture.

scholarly journals Role of Oxidative Stress in Heart Failure: Insights from Gene Transfer Studies

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1645
Author(s):  
Bart De Geest ◽  
Mudit Mishra
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Gene Therapy ◽  
Steady State ◽  
Gene Transfer ◽  
Oxidative Modification ◽  
Heme Oxygenase 1 ◽  
Therapy Studies ◽  
Pathological Remodeling

Under physiological circumstances, there is an exquisite balance between reactive oxygen species (ROS) production and ROS degradation, resulting in low steady-state ROS levels. ROS participate in normal cellular function and in cellular homeostasis. Oxidative stress is the state of a transient or a persistent increase of steady-state ROS levels leading to disturbed signaling pathways and oxidative modification of cellular constituents. It is a key pathophysiological player in pathological hypertrophy, pathological remodeling, and the development and progression of heart failure. The heart is the metabolically most active organ and is characterized by the highest content of mitochondria of any tissue. Mitochondria are the main source of ROS in the myocardium. The causal role of oxidative stress in heart failure is highlighted by gene transfer studies of three primary antioxidant enzymes, thioredoxin, and heme oxygenase-1, and is further supported by gene therapy studies directed at correcting oxidative stress linked to metabolic risk factors. Moreover, gene transfer studies have demonstrated that redox-sensitive microRNAs constitute potential therapeutic targets for the treatment of heart failure. In conclusion, gene therapy studies have provided strong corroborative evidence for a key role of oxidative stress in pathological remodeling and in the development of heart failure.

scholarly journals Elucidating the Role of IL6 in Stress Erythropoiesis and in the Development of Anemia Under Inflammatory Conditions

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 940-940
Author(s):  
Sayantani Sinha ◽  
Ritama Gupta ◽  
Jianbing Zhang ◽  
Amaliris Guerra ◽  
Ping La ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
Inflammatory Cytokines ◽  
Reticulocyte Count ◽  
Erythroid Cell ◽  
Deficiency Anemia ◽  
Iron Dextran ◽  
Erythroid Cells ◽  
Second Wave

Anemia of inflammation, also known as anemia of chronic disease is the second most common anemia after iron deficiency anemia. The predominant regulators of AI are the cytokine-interleukin-6 (IL6) and the hormone hepcidin (Hamp). IL6 has been implicated in inducing expression of hepcidin. Published data from our lab have shown that lack of IL6 or hepcidin in knockout mouse models (IL6-KO and Hamp-KO) injected with the heat-killed pathogen Brucella abortus(BA) results in recovery from anemia but interestingly the pattern of the recovery was different in IL6-KO and Hamp-KO mice, suggesting that the two proteins contribute independently to AI. Here, we validated the independent role of IL6 and Hamp in AI by generating a double-knockout (DKO) mouse model lacking the expression of both. In the first few days following BA administration, we observed severe reduction in the total number of BM cells in each model followed by a slow recovery in erythroid and multilineage hematopoietic cells. The recovery, initially, was more sustained in the BA-treated-DKO model. In particular, in the first week, BA-treated-DKO mice showed an increased number of erythroblasts in the bone marrow (BM) and spleen as seen in comparison to IL6-KO and Hamp-KO. IL6-KO mice showed an intermediate recovery profile when compared to DKO and Hamp-KO, the last one showing the worst profile in the BM. Interestingly, when the reticulocyte count in the DKO mice was compared to that of IL6-KO and Hamp-KO mice, it showed a biphasic trend, with a significant increase in number during the 2nd week, followed by a significant reduction during the 3rd week. We hypothesized that the initial surge in reticulocyte count in DKO was due to lack of hepcidin, which increases iron availability to erythroid cells, and concurrent lack of IL6, which favors BM erythropoiesis in presence of inflammatory stimuli. However, we also speculated that the excess of iron (as NTBI), which accumulates during the first two weeks, leads to oxidative stress and erythroid cell death in presence of inflammatory cytokines, despite the absence of IL6. We also surmised that, during the second week, a second wave of inflammatory cytokines is triggered by the adaptive response in response to the BA that would explain the negative effect on erythropoiesis after the initial recovery. To assess this hypothesis, we utilized an inflammation panel to analyze the cytokine expression in WT animals treated with PBS or BA at 6 hours, 24 hours and then around ~2 weeks. The cytokine levels were normalized after 24 hours. However, around two weeks, we observed a novel surge of cytokines such as IFN-g and TNFa in the BA treated mice, indicating their role in innate (immediate effect; 6 hours) and adaptive immune response, which activated a second wave of inflammation (around 2 weeks, during the recovery of hematopoiesis in the BM). Interestingly, while we observed oxidative stress and defective erythropoiesis in the bone marrow, this was not seen in the spleen, where increased and extramedullary erythropoiesis sustained some level of RBC production. Since the BA-treated-IL6-KO did not show any major defect in the BM after two weeks, we challenged them with administration of iron dextran. Upon treatment, also the IL6-KO mice treated with both BA and iron dextran shown increased production of reactive oxygen species as well as a defect in bone marrow erythropoiesis, similarly as in DKO or Hamp-KO mice, thereby explaining the plausible reason of reduced erythropoiesis in the bone-marrow. Furthermore, to identify mechanisms leading to oxidative stress, we established an in-vitro culture system where primary murine bone marrow cells were cultured for 18-20 hours in presence of serum isolated after 6hrs from either PBS treated or BA treated C57BL/6 mice. With the help of confocal microscopy, we observed an increase in mitochondrial superoxide in the cells treated with BA serum; interestingly we have also seen a decrease in Ter 119 population in the cells cultured with BA treated serum implicating that the erythroid cells are dying. To further investigate the downstream players related to the death of erythroid progenitors we are currently investigating the role caspase 1 (a major regulator in pyroptosis) and Gata-1. In conclusion, this study is elucidating some of the mechanisms associated with the anemia triggered by inflammation with the potential to identify new targets and treatments. Disclosures Rivella: Disc medicine, Protagonist, LIPC, Meira GTx: Consultancy; Meira GTx, Ionis Pharmaceutical: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Cytoprotection of human endothelial cells from oxidative stress by polyphenols: the role of gene expression versus direct antioxidant effect

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Xinyu Wang ◽  
James Bynum ◽  
Salomon Stavchansky ◽  
Michael Dubick ◽  
Robert Hackman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Endothelial Cells ◽  
Antioxidant Effect ◽  
Human Endothelial Cells

Role of the Hypoxia-Inducible Factor Pathway in Normal and Osteoarthritic Meniscus and in Mice after Destabilization of the Medial Meniscus

Cartilage ◽  
2020 ◽  
pp. 194760352095814
Author(s):  
Austin V. Stone ◽  
Richard F. Loeser ◽  
Michael F. Callahan ◽  
Margaret A. McNulty ◽  
David L. Long ◽  
...  
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Medial Meniscus ◽  
Transforming Growth Factor ◽  
Hypoxia Inducible Factor ◽  
Early Time ◽  
Wild Type ◽  
Inflammatory Stimuli ◽  
Hif Pathway

Objective Meniscus injury and the hypoxia-inducible factor (HIF) pathway are independently linked to osteoarthritis pathogenesis, but the role of the meniscus HIF pathway remains unclear. We sought to identify and evaluate HIF pathway response in normal and osteoarthritic meniscus and to examine the effects of Epas1 (HIF-2α) insufficiency in mice on early osteoarthritis development. Methods Normal and osteoarthritic human meniscus specimens were obtained and used for immunohistochemical evaluation and cell culture studies for the HIF pathway. Meniscus cells were treated with pro-inflammatory stimuli, including interleukins (IL)-1β, IL-6, transforming growth factor (TGF)-α, and fibronectin fragments (FnF). Target genes were also evaluated with HIF-1α and HIF-2α (Epas1) overexpression and knockdown. Wild-type ( n = 36) and Epas1+/− ( n = 30) heterozygous mice underwent destabilization of the medial meniscus (DMM) surgery and were evaluated at 2 and 4 weeks postoperatively for osteoarthritis development using histology. Results HIF-1α and HIF-2α immunostaining and gene expression did not differ between normal and osteoarthritic meniscus. While pro-inflammatory stimulation significantly increased both catabolic and anabolic gene expression in the meniscus, HIF-1α and Epas1 expression levels were not significantly altered. Epas1 overexpression significantly increased Col2a1 expression. Both wild-type and Epas1+/− mice developed osteoarthritis following DMM surgery. There were no significant differences between genotypes at either time point. Conclusion The HIF pathway is likely not responsible for osteoarthritic changes in the human meniscus. Additionally, Epas1 insufficiency does not protect against osteoarthritis development in the mouse at early time points after DMM surgery. The HIF pathway may be more important for protection against catabolic stress.

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