The effect of hypoxia mimetic cobalt chloride on the expression of EC-SOD in 3T3-L1 adipocytes

Enhancing adipose tissue functionality in obesity: senotherapeutics, autophagy and cellular senescence as a target

Obesity, a global health crisis, disrupts multiple systemic processes, contributing to a cascade of metabolic dysfunctions by promoting the pathological expansion of visceral adipose tissue (VAT). This expansion is characterized by impaired differentiation of pre-adipocytes and an increase in senescent cells, leading to a pro-inflammatory state and exacerbated oxidative stress. Particularly, the senescence-associated secretory phenotype (SASP) and adipose tissue hypoxia further impair cellular function, promoting chronic disease development. This review delves into the potential of autophagy modulation and the therapeutic application of senolytics and senomorphics as novel strategies to mitigate adipose tissue senescence. By exploring the intricate mechanisms underlying adipocyte dysfunction and the emerging role of natural compounds in senescence modulation, we underscore the promising horizon of senotherapeutics in restoring adipose health. This approach not only offers a pathway to combat the metabolic complications of obesity, but also opens new avenues for enhancing life quality and managing the global burden of obesity-related conditions. Our analysis aims to bridge the gap between current scientific progress and clinical application, offering new perspectives on preventing and treating obesity-induced adipose dysfunction.

Signal transducer and activator of transcription-3 mediated neuroprotective effect of interleukin-6 on cobalt chloride mimetic hypoxic cell death in R28 cells

BACKGROUND

Hypoxic injury to retinal ganglionic cells and adjoining glia is implicated in glaucomatous optic neuropathy. The present study evaluates the effect of IL-6 on R28 retinal precursor cell line exposed to hypoxic injury.

METHODS AND RESULTS

Apoptotic cell death induced by hypoxia mimetic CoCl₂ in R28 cells with or without IL-6 treatment was measured using cell viability assays and apoptotic markers. Oxidative stress was also measured. Hypoxia induced by mimetic CoCl₂ led to a time and concentration dependent apoptosis of cells mediated by disruption of mitochondrial membrane potential and activation of caspase 3. Cells pre-treated with IL-6 demonstrated significantly higher viability and mitochondrial integrity under hypoxic conditions. A critical role of STAT3 was observed in mediating the cytoprotective effects of IL-6. Treatment of cells with IL-6 led to STAT3-mediated expression of the Bcl-2 family proteins and MnSOD.

CONCLUSIONS

The data from the present study indicate cytoprotective role of IL-6 and suggest a previously unreported mechanism of neuroprotection via STAT3 mediated signaling.

[Regulation of Extracellular Redox Homeostasis in Tumor Microenvironment]

Excessive generation of reactive oxygen species (ROS) has been implicated in the progression of tumors. Superoxide dismutase 3 (SOD3) is a copper-containing secretory antioxidative enzyme that plays a critical role in redox homeostasis, particularly in extracellular spaces. Considerable evidence suggests that SOD3 protein expression is significantly decreased or lost in several tumor tissues, and this loss results in tumor metastasis. On the other hand, epigenetic disturbances, including DNA hyper-/hypomethylation, histone de/acetylation, and histone de/methylation, may be involved in tumorigenesis and the progression of metastasis. However, regulation of SOD3 in the tumor microenvironment and the involvement of epigenetics in its expression remain unclear. To elucidate the molecular mechanisms underlying SOD3 expression, we investigated the involvement of epigenetics, including DNA methylation and histone modifications, in its regulation in tumor cells and macrophages. SOD3 expression in human monocytic THP-1 cells and human lung cancer A549 cells was silenced by DNA hypermethylation within the SOD3 promoter region. Furthermore, the DNA demethylase, ten-eleven translocation 1, was shown for the first time to play a key role in regulation of DNA methylation within that region. We also demonstrated that myocyte enhancer factor 2 functioned as one of the transcription factors of SOD3 expression in THP-1 cells. Collectively, these novel results will contribute to the elucidation of epigenetic redox regulation, and may provide important insights into tumorigenesis and tumor metastasis.

Chemical Inducers of Obesity-Associated Metabolic Stress Activate Inflammation and Reduce Insulin Sensitivity in 3T3-L1 Adipocytes

Obesity is accompanied by dyslipidemia, hypoxia, endoplasmic reticulum (ER) stress, and inflammation, representing the major risk factor for the development of insulin resistance (IR) and type 2 diabetes. We modeled these conditions in cultured 3T3-L1 adipocytes and studied their effect on insulin signaling, glucose uptake, and inflammatory response via activation of stress-dependent JNK1/2 kinases. Decreased insulin-induced phosphorylation of the insulin cascade components IRS, Akt, and AS160 was observed under all tested conditions (lipid overloading of cells by palmitate, acute inflammation induced by bacterial lipopolysaccharide, hypoxia induced by Co2+, and ER stress induced by brefeldin A). In all the cases, except the acute inflammation, glucose uptake by adipocytes was reduced, and the kinetics of JNK1/2 activation was bi-phasic exhibiting sustained activation for 24 h. By contrast, in acute inflammation, JNK1/2 phosphorylation increased transiently and returned to the basal level within 2-3 h of stimulation. These results suggest a critical role of sustained (latent) vs. transient (acute) inflammation in the induction of IR and impairment of glucose utilization by adipose tissue. The components of the inflammatory signaling can be promising targets in the development of new therapeutic approaches for preventing IR and type 2 diabetes.

Terminalia arjuna extract and arjunic acid mitigate cobalt chloride-induced hypoxia stress-mediated apoptosis in H9c2 cells

Arjunic acid (AA) is one of the major active component of Terminalia arjuna known for its health benefits. In the present study, we evaluated cardioprotective potential of Terminalia arjuna extract (TAE) and AA against cobalt chloride (CoCl₂)-induced hypoxia damage and apoptosis in rat cardiomyocytes. TAE (50 μg/ml) and AA (8 μg/ml) significantly (p < 0.001) protected H9c2 cells as evidenced by cell viability assays against CoCl₂ (1.2 mM)-induced cytotoxicity. TAE and AA pretreatments protected the cells from oxidative damage by decreasing the generation of free radicals (ROS, hydroperoxide, and nitrite levels). TAE and AA pretreatments retained mitochondrial membrane potential by alleviating the rate of lipid peroxidation induced by CoCl₂ treatment. TAE and AA pretreatments elevated antioxidant status including phase II antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and total glutathione levels against CoCl₂-induced oxidative stress. Further immunoblotting studies confirmed anti-apoptotic effects of TAE and AA by alleviating the phosphorylation of JNK and c-jun and also by regulating protein expression levels of Bcl2, Bax, caspase 3, heat shock protein-70, and inducible nitric oxide synthase. Overall, our results suggest that both the extract and the active component exhibit antioxidant and anti-apoptotic defense against CoCl₂-induced hypoxic injury.

Growth Factor-Reinforced ECM Fabricated from Chemically Hypoxic MSC Sheet with Improved In Vivo Wound Repair Activity

MSC treatment can promote cutaneous wound repair through multiple mechanisms, and paracrine mediators secreted by MSC are responsible for most of its therapeutic benefits. Recently, MSC sheet composed of live MSCs and their secreted ECMs was reported to promote wound healing; however, whether its ECM alone could accelerate wound closure remained unknown. In this study, Nc-ECM and Cc-ECM were prepared from nonconditioned and CoCl₂-conditioned MSC sheets, respectively, and their wound healing properties were evaluated in a mouse model of full-thickness skin defect. Our results showed that Nc-ECM can significantly promote wound repair through early adipocyte recruitment, rapid reepithelialization, enhanced granulation tissue growth, and augmented angiogenesis. Moreover, conditioning of MSC sheet with CoCl₂ dramatically enriched its ECM with collagen I, collagen III, TGF-β1, VEGF, and bFGF via activation of HIF-1α and hence remarkably improved its ECM's in vivo wound healing potency. All the Cc-ECM-treated wounds completely healed on day 7, while Nc-ECM-treated wounds healed about 85.0% ± 8.6%, and no-treatment wounds only healed 69.8% ± 9.6% (p < 0.05). Therefore, we believe that such growth factor-reinforced ECM fabricated from chemically hypoxic MSC sheet has the potential for clinical translation and will lead to a MSC-derived, cost-effective, bankable biomaterial for wound management.

Vitamin D Reduces Oxidative Stress-Induced Procaspase-3/ROCK1 Activation and MP Release by Placental Trophoblasts

CONTEXT

Increased microparticle (MP) shedding by placental trophoblasts contributes to maternal vascular inflammatory response and endothelial dysfunction in preeclampsia. Vitamin D has beneficial effects in pregnancy; however, its effect on trophoblast MP release has not been investigated.

OBJECTIVE

To investigate if vitamin D could protect trophoblasts from oxidative stress-induced MP release.

DESIGN

Placental trophoblasts were isolated from uncomplicated and preeclamptic placentas. Effects of vitamin D on MP release induced by oxidative stress inducer CoCl2 were studied.

MAIN OUTCOME MEASURES

Annexin V+ MPs were assessed by flow cytometry. Expression of caveolin-1, endothelial nitric oxide synthase (eNOS), procaspase-3, cleaved caspase-3, and Rho-associated coiled-coil protein kinase 1 (ROCK1) in trophoblasts and trophoblast-derived MPs were determined by Western blot.

RESULTS

Trophoblasts from preeclamptic pregnancies released significantly more MPs than cells from uncomplicated pregnancies (P < 0.01). CoCl2-induced increase in MP release was associated with upregulation of caveolin-1 and downregulation of eNOS expression in trophoblasts (P < 0.05), which could be attenuated by 1,25(OH)2D3. Moreover, 1,25(OH)2D3 could also inhibit CoCl2-induced procaspase-3 cleavage and ROCK1 activation in trophoblasts. Consistently, CoCl2-induced upregulation of procaspase-3, cleaved caspase-3, and ROCK1 expression in trophoblast-derived MPs were also reduced in cells treated with 1,25(OH)2D3.

CONCLUSIONS

Placental trophoblasts from preeclamptic pregnancies released more MP than cells from uncomplicated pregnancies. Oxidative stress-induced increase in MP shedding is associated with upregulation of caveolin-1 and downregulation of eNOS expression in placental trophoblasts. Inhibition of caspase-3 cleavage and ROCK1 activation, together with upregulation of eNOS expression, could be the potential cellular/molecular mechanism(s) of vitamin D protective effects on placental trophoblasts.

Ras oncogene-mediated progressive silencing of extracellular superoxide dismutase in tumorigenesis

Extracellular superoxide dismutase (SOD3) is a secreted enzyme that uses superoxide anion as a substrate in a dismutase reaction that results in the formation of hydrogen peroxide. Both of these reactive oxygen species affect growth signaling in cells. Although SOD3 has growth-supporting characteristics, the expression of SOD3 is downregulated in epithelial cancer cells. In the current work, we studied the mechanisms regulating SOD3 expression in vitro using thyroid cell models representing different stages of thyroid cancer. We demonstrate that a low level of RAS activation increases SOD3 mRNA synthesis that then gradually decreases with increasing levels of RAS activation and the decreasing degree of differentiation of the cancer cells. Our data indicate that SOD3 regulation can be divided into two classes. The first class involves RAS–driven reversible regulation of SOD3 expression that can be mediated by the following mechanisms: RAS GTPase regulatory genes that are responsible for SOD3 self-regulation; RAS-stimulated p38 MAPK activation; and RAS-activated increased expression of the mir21 microRNA, which inversely correlates with sod3 mRNA expression. The second class involves permanent silencing of SOD3 mediated by epigenetic DNA methylation in cells that represent more advanced cancers. Therefore, the work suggests that SOD3 belongs to the group of ras oncogene-silenced genes.

Oxidized low-density lipoprotein accelerates the destabilization of extracellular-superoxide dismutase mRNA during foam cell formation

Extracellular-superoxide dismutase (EC-SOD) is one of the main anti-oxidative enzymes that protect cells against the damaging effects of superoxide. In the present study, we investigated the regulation of EC-SOD expression during the oxidized low density lipoprotein (oxLDL)-induced foam cell formation of THP-1-derived macrophages. The uptake of oxLDL into THP-1-derived macrophages was increased and EC-SOD expression was decreased in a time-dependent manner by oxLDL. Furthermore, EC-SOD suppression by oxLDL was mediated by the binding to scavenger receptors, especially CD36, from the results with siRNA experience. EC-SOD expression is known to be regulated by histone acetylation and binding of the transcription factor Sp1/3 to the EC-SOD promoter region in human cell lines. However, oxLDL did not affect these processes. On the other hand, the stability of EC-SOD mRNA was decreased by oxLDL. Moreover, oxLDL promoted destabilization of ectopically expressed mRNA from EC-SOD or chimeric Cu,Zn-SOD gene with the sequence corresponding to 3'UTR of EC-SOD mRNA, whereas oxLDL had no effect on ectopic mRNA produced from EC-SOD gene lacking the sequence. These results suggested that oxLDL decreased the expression of EC-SOD, which, in turn, accelerated the destabilization of EC-SOD mRNA, leading to weaker protection against oxidative stress and atherosclerosis.

Activation of vitamin D receptor promotes VEGF and CuZn-SOD expression in endothelial cells

Endothelial dysfunction associated with vitamin D deficiency has been linked to many chronic vascular diseases. Vitamin D elicits its bioactive actions by binding to its receptor, vitamin D receptor (VDR), on target cells and organs. In the present study, we investigated the role of VDR in response to 1,25(OH)₂D₃ stimulation and oxidative stress challenge in endothelial cells. We found that 1,25(OH)₂D₃ not only induced a dose- and time-dependent increase in VDR expression, but also induced up-regulation of vascular endothelial growth factor (VEGF) and its receptors (Flt-1 and KDR), as well as antioxidant CuZn-superoxide dismutase (CuZn-SOD) expression in endothelial cells. We demonstrated that inhibition of VDR by VDR siRNA blocked 1,25(OH)₂D₃ induced increased VEGF and KDR expression and prevented 1,25(OH)₂D₃ induced endothelial proliferation/migration. Using CoCl₂, a hypoxic mimicking agent, we found that hypoxia/oxidative stress not only reduced CuZn-SOD expression, but also down-regulated VDR expression in endothelial cells, which could be prevented by addition of 1,25(OH)₂D3 in culture. These findings are important indicating that VDR expression is inducible in endothelial cells and oxidative stress down-regulates VDR expression in endothelial cells. We conclude that sufficient vitamin D levels and proper VDR expression are fundamental for angiogenic and oxidative defense function in endothelial cells.

Down-regulation of TIMP3 leads to increase in TACE expression and TNFα production by placental trophoblast cells

PROBLEM

To determine whether down-regulation of TIMP3 expression promotes TACE expression and increases in TNFα production by placental trophoblast cells.

METHOD OF STUDY

Placental expression of TIMP3 and TACE was examined by immunostaining and Western blot. Effects of TIMP3 on TACE expression and TNFα production were assessed by transfection of TIMP3 siRNA into trophoblasts isolated from normal placentas. Effects of oxidative stress on trophoblast TIMP3 expression and TNFα production were also determined. Trophoblast production of TIMP3, TACE and TNFα were measured by ELISA.

RESULTS

TIMP3 expression was markedly reduced in preeclamptic placentas compared with normal placentas; oxidative stress down-regulated trophoblast TIMP3 expression and production, P < 0.01. Down-regulation of TIMP3 expression by TIMP3 siRNA resulted in significant increases in TACE expression and TNFα production, P < 0.01.

CONCLUSION

As TIMP3 is an endogenous TACE inhibitor, down-regulation of trophoblast TIMP3 expression/activity could result in increased TACE expression and subsequently lead to increased TNFα production in preeclamptic placentas.

1,25(OH)2D3 suppresses COX-2 up-regulation and thromboxane production in placental trophoblast cells in response to hypoxic stimulation

In this study, we determined if vitamin D could inhibit oxidative stress-induced thromboxane production by placental trophoblasts. Trophoblast isolated from normal placentas were stimulated with CoCl2, a hypoxic mimicking agent, with or without pretreatment of 1,25(OH)2D3. Soluble phospholipase-A2, metabolites of thromboxane-A2 and prostacyclin, and 8-isoprostane were measured. Expression of cyclooxygenase-1 (COX-1), COX-2, and heme oxygenase-1 (HO-1) were determined. We found that pretreatment of trophoblasts with 1,25(OH)2D3 significantly reduced 8-isoprostane and the ratio of thromboxane-A2 to prostacyclin production, and blocked COX-2 expression induced by CoCl2. These results provide evidence of the beneficial effects of vitamin D on placental trophoblasts.

Effect of endoplasmic reticulum (ER) stress inducer thapsigargin on the expression of extracellular-superoxide dismutase in mouse 3T3-L1 adipocytes

Endoplasmic reticulum stress is related to metabolic disorders, including atherosclerosis and type 2 diabetes. It is known that inflammatory adipocytokines and oxidative stress are increased, while anti-inflammatory adipocytokines such as adiponectin are decreased in adipocytes during above conditions. Extracellular-superoxide dismutase is an anti-inflammatory enzyme that protects cells from oxidative stress. Because plasma extracellular-superoxide dismutase levels in type 2 diabetes patients were inversely related to the body mass index and homeostasis model assessment-insulin resistance index, it is speculated that the regulation of extracellular-superoxide dismutase might lead to the suppression of metabolic disorders. Here, we observed the reduction of extracellular-superoxide dismutase and adiponectin in 3T3-L1 adipocytes treated with thapsigargin, an endoplasmic reticulum stress inducer. Interestingly, tunicamycin, another endoplasmic reticulum stress inducer, did not decrease the expression of extracellular-superoxide dismutase in spite of the induction of glucose regulated protein kinase 78 kDa, an endoplasmic reticulum stress marker. Moreover, eukaryotic translation initiation factor 2α signaling cascade plays a pivotal role in the reduction of extracellular-superoxide dismutase in 3T3-L1 adipocytes during endoplasmic reticulum stress conditions.

Expressions of vitamin D metabolic components VDBP, CYP2R1, CYP27B1, CYP24A1, and VDR in placentas from normal and preeclamptic pregnancies

Vitamin D insufficiency/deficiency during pregnancy has been linked to increased risk of preeclampsia. Placenta dysfunction plays an important role in the pathogenesis of this pregnancy disorder. In this study, we tested the hypothesis that disturbed vitamin D metabolism takes place in preeclamptic placentas. Protein expressions of vitamin D binding protein (VDBP), 25-hydroxylase (CYP2R1), 1α-hydroxylase (CYP27B1), 24-hydroxylase (CYP24A1), and vitamin D receptor (VDR) were examined in placentas from normotensive and preeclamptic pregnancies. By immunostaining we found that in normal placenta VDBP, CYP24A1, and VDR expressions are localized mainly in trophoblasts, whereas CYP2R1 and CYP27B1 expressions are localized mainly in villous core fetal vessel endothelium. Protein expressions of CYP2R1 and VDR are reduced, but CYP27B1 and CYP24A1 expressions are elevated, in preeclamptic compared with normotensive placentas. Because increased oxidative stress is an underlying pathophysiology in placental trophoblasts in preeclampsia, we further determined whether oxidative stress contributes to altered vitamin D metabolic system in placental trophoblasts. Trophoblasts isolated from normal-term placentas were treated with hypoxic-inducing agent CoCl(2), and protein expressions of VDBP, CYP2R1, CYP27B1, CYP24A1, and VDR were determined. We found that hypoxia-induced downregulation of VDBP, CYP2R1, and VDR and upregulation of CYP27B1 and CYP24A1 expressions were consistent with that seen in preeclamptic placentas. CuZnSOD expression was also downregulated in trophoblasts treated with CoCl(2). These results provide direct evidence of disrupted vitamin D metabolic homeostasis in the preeclamptic placenta and suggest that increased oxidative stress could be a causative factor of altered vitamin D metabolism in preeclamptic placentas.

Effects of hyperoxia exposure on metabolic markers and gene expression in 3T3-L1 adipocytes

Adipose tissue often becomes poorly oxygenated in obese subjects. This feature may provide cellular mechanisms involving chronic inflammation processes such as the release of pro-inflammatory cytokines and macrophage infiltration. In this context, the purpose of the present study was to determine whether a hyperoxia exposure on mature adipocytes may influence the expression of some adipokines and involve favorable changes in specific metabolic variables. Thus, 3T3-L1 adipocytes (14 days differentiated) were treated with 95 % oxygen for 24 h. Cell viability, intra and extracellular reactive oxygen species (ROS) content, glucose uptake, as well as lactate and glycerol concentrations were measured in the culture media. Also, mRNA levels of hypoxia-inducible factor (HIF)-1α, leptin, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, peroxisome proliferator-activated receptor (PPAR)-γ, adiponectin, and angiopoietin-related protein (ANGPTL)4 were analyzed. Hyperoxia treatment increased intra and extracellular ROS content, reduced glucose uptake and lactate release and increased glycerol release. Additionally, a higher oxygen tension led to an upregulation of the expression of IL-6, MCP-1, and PPAR-γ, while ANGPTL4 was downregulated in the hyperoxia group with respect to control. The present data shows that hyperoxia treatment seems to produce an inflammatory response due to the release of ROS and the upregulation of pro-inflammatory adipokines, such as IL-6 and MCP-1. On the other hand, hyperoxia may have an indirect effect on insulin sensitivity due to the upregulation of PPAR-γ signaling as well as a possible modulation of both glucose and lipid metabolic markers. To our knowledge, this is the first study analyzing the effect of hyperoxia in 3T3-L1 adipocytes.

Extracellular-superoxide dismutase expression in COS7 cells exposed to cadmium chloride

Cadmium (Cd), an industrial and environmental pollutant, preferentially accumulates in the kidney, a major target for Cd-related toxicity. It has been reported that Cd exposure produces reactive oxygen species (ROS) and induces cytotoxicity. Extracellular-superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects the cells from damaging effects of ROS; however, the effect of Cd on the expression of EC-SOD in COS7 cells remains unclear. In this study, exposure to cadmium chloride (CdCl₂) enhanced intracellular ROS generation and induced COS7 cell death. Moreover, exposure to Cd decreased the expression of EC-SOD at mRNA and protein levels, but not of other SOD isozymes, copper-and zinc-containing SOD and manganese-containing SOD. The reduction of EC-SOD and cell viability was partially attenuated by pretreatment with an antioxidant, N-acetylcysteine. Further, we determined the involvement of p38-mitogen-activated protein kinase (p38-MAPK) in the reduction of EC-SOD. From these observations, p38-MAPK signaling cascades activated by ROS play a pivotal role in the reduction of EC-SOD, and it is concluded that the reduction of EC-SOD leads to a decrease in the resistance to oxidative stress of Cd-exposed COS7 cells.

Regulation of skin inflammation and angiogenesis by EC-SOD via HIF-1α and NF-κB pathways

Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that breaks down superoxide anion into oxygen and hydrogen peroxide in extracellular spaces and plays key roles in controlling pulmonary and vascular diseases in response to oxidative stresses. We aimed to investigate the role of EC-SOD in angiogenesis and inflammation in chronic inflammatory skin disorders such as psoriasis. Overexpressed EC-SOD reduced expression of angiogenic factors and proinflammatory mediators in hypoxia-induced keratinocytes and in ultraviolet B-irradiated mice, whereas the expression of the antiangiogenic factor tissue inhibitor of metalloproteinase-1 and anti-inflammatory cytokine interleukin-10 were increased. EC-SOD decreased new vessel formation, epidermal edema, and inflammatory cell infiltration in UVB-irradiated transgenic mice. Moreover, cells treated with recombinant human EC-SOD showed inhibited endothelial tube formation and cell proliferation. Overall, the antiangiogenic and anti-inflammatory effects of EC-SOD might be due to suppression of hypoxia-inducible factor-1α, protein kinase C, and nuclear factor-κB expression. Furthermore, EC-SOD expression in tissue from psoriasis patients was markedly decreased in psoriatic lesional and nonlesional skins from psoriasis patients in comparison to normal skin from healthy volunteers. Together, these results suggest that EC-SOD may provide a novel therapeutic approach to treating angiogenic and inflammatory skin diseases such as psoriasis.

ADAM17 regulates TNFα production by placental trophoblasts

Increased trophoblast TNFα production is an important component of placental dysfunction in preeclampsia. However, the mechanism of increased TNFα production in the preeclamptic placenta is largely unknown. ADAM17 is a metallopeptidase that functions as a TNFα converting enzyme. In this study, we examined ADAM17 expression in placentas from normal and preeclamptic pregnancies and found increased ADAM17 expression in preeclamptic placentas compared to those from normal placentas, p < 0.05. Since hypoxia/oxidative stress is an underlying pathophysiology in the preeclamptic placenta, we further determined if hypoxia/oxidative stress could modulate ADAM17 expression and subsequently induce TNFα production in placental trophoblasts. Trophoblasts were isolated from normal term placentas and treated with cobalt (II) chloride (CoCl(2)), a hypoxia mimetic agent, at different concentrations. Our results showed that CoCl(2) induced a dose-dependent increase in TNFα production that is associated with enhanced ADAM17 expression. Trophoblast expressions of HO-1 (a sensor of cellular oxidative stress) and caspase-3 (an indicator of apoptosis) in response to CoCl(2) stimulation were also examined. We further found that metallopeptidase inhibitor GM6001 and ADAM17 siRNA could block CoCl(2) induced TNFα production, demonstrating the role of ADAM17 in TNFα production in placental trophoblasts. These results suggest that oxidative stress-induced increased ADAM17 expression could contribute to the increased TNFα production in preeclamptic placentas.