Activated Platelets Induce Hypoxia-Inducible Factor-1α Expression Likely through Transforming Growth Factor-β1 in Human Endometrial Stromal Cells

“Expression values were normalized to the geometric mean of GAPDH measurements, and the quantification of mRNA abundance was made using the method described previously.[26]”

“[31,32] VEGF, a major driver of angiogenesis in cancer and in endometriosis, is also transcriptionally regulated by HIF-1α under hypoxic conditions.[33] HIF-1α binds to the HRE regions of the VEGF promoter and is positively correlated with VEGF expression in endometriosis.”

“[30] HIF-1α-induced COX-2 expression leads to elevated prostaglandin E2 (PGE2) levels, which can induce PGE2-mediated vascularization.[31,32] VEGF, a major driver of angiogenesis in cancer and in endometriosis, is also transcriptionally regulated by HIF-1α under hypoxic conditions.”

“The EPO gene is under the direct control of hypoxia through HIF-1α, which then binds to a cis-acting DNA site in the HRE of the EPO gene promoter.[36,37] EPO, a widely known growth factor in erythropoiesis, can also stimulate angiogenesis,[38] as well as tumor cell proliferation and survival.”

“One hallmark of hypoxia is the overexpression of the transcription factor hypoxia-inducible factor-1α (HIF-1α), a key mediator of cellular adaptation to low oxygen levels and a potential target for many types of cancer, such as ovarian, prostate, and breast;[6] HIF-1α expression reflects the degree of cell hypoxia; it…”

“We note that HIF-1α has also been reported to promote epithelial–mesenchymal transition (EMT) in several types of cancer by modulating one or more EMT-associated genes.[53] Moreover, in this study, we demonstrated that TGF-β1 neutralization completely abolishes platelet-induced HIF-1α expression in endometriotic cells.”

“HIF consists of two subunits, α and β, which form a heterodimeric complex.[28] HIF-1β is present under both normoxia and hypoxia, while HIF1α is present only under hypoxic conditions.”

“[29] For example, COX-2 expression is regulated by HIF-1α transcriptional activity.[30] HIF-1α-induced COX-2 expression leads to elevated prostaglandin E2 (PGE2) levels, which can induce PGE2-mediated vascularization.”

“The EPO gene is under the direct control of hypoxia through HIF-1α, which then binds to a cis-acting DNA site in the HRE of the EPO gene promoter.[36,37] EPO, a widely known growth factor in erythropoiesis, can also stimulate angiogenesis,[38] as well as tumor cell proliferation and survival.”

“The increased TGF-β1 expression in endometriosis has been well documented.[45-48] In a gene profiling study on a mouse”

“[28] As a transcription factor, HIF-1α regulates the activities of its downstream genes by binding the HREs in their promoter regions.[29] For example, COX-2 expression is regulated by HIF-1α transcriptional activity.”

“[36,37] EPO, a widely known growth factor in erythropoiesis, can also stimulate angiogenesis,[38] as well as tumor cell proliferation and survival.”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“However, the ectopic and eutopic endometria are known to be transcriptionally different,[4] and the difference is presumably attributed to their different microenvironments, the key factor that determines the difference is still unclear.”

“model, TGF-β1 has been identified to play important roles in the gene network involved in the pathogenesis of endometriosis.[49]”

“[51] On the other hand, exposure to TGF-β1 could increase HIF-1α gene and protein expression in many cell types.[48,50,52] In this study, we found that neutralization of TGF-β1 completely abolished the HIF-1α induction by activated platelets in both HESC and ESCL, highlighting the important role of platelets in the in…”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“[30] HIF-1α-induced COX-2 expression leads to elevated prostaglandin E2 (PGE2) levels, which can induce PGE2-mediated vascularization.”

“[9] This is consistent with the report that both endometriotic and endometrial stromal cells have elevated expression of myofibroblast markers after stimulation with TGF-β1.[54] While it may seem logical that the TGF-β1/ Smad3 pathway is a therapeutic target for endometriosis, it is worth noting that this pathway also…”

“It has been reported that TGF-β1 promoter activity is regulated by hypoxia, and that HIF-1α could directly regulate TGF-β1 expression through the HRE, which is located in the TGF-β1 proximal promoter.[51] On the other hand, exposure to TGF-β1 could increase HIF-1α gene and protein expression in many cell types.”

“Hypoxia is an important factor that regulates numerous physiological and pathological processes.[41] It has been reported”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“the transcriptional activation of hypoxia-regulated genes, including erythropoietin (EPO), vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2),[10,11] which are”

“[51] On the other hand, exposure to TGF-β1 could increase HIF-1α gene and protein expression in many cell types.[48,50,52] In this study, we found that neutralization of TGF-β1 completely abolished the HIF-1α induction by activated platelets in both HESC and ESCL, highlighting the important role of platelets in the in…”

“of HIF-1α.[9,12] This may explain why endometrial debris invades and establish endometriotic foci in ectopic sites.”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“Preparation of platelets Platelets were isolated by centrifugation at room temperature of whole blood samples donated by healthy male volunteers who provided informed consent and did not take any medications for at least 2 weeks prior to donation as reported previously.[25] The blood was first centrifuged at 150 ×g fo…”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“Recently, it has been shown that hypoxia plays a critical role in the survival and angiogenesis of ectopic endometrial cells regurgitated from the uterus.[5] Remarkably, hypoxic conditions alone dramatically change the behavior of endometrial cells that are otherwise “normal.”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“Reproductive and Developmental Medicine ¦ June 25, 2019 ¦ Volume 3 ¦ Issue 2 71 buffered saline (PBS) three times to remove the platelets as reported previously.[19]”

“[1] Despite extensive research, its pathogenesis remains elusive.[2] One widely accepted theory is the retrograde menstruation theory proposed by Sampson,[3] which stipulates that, when viable endometrial cells are regurgitated into the pelvic cavity through the fallopian tubes, they somehow invade the peritoneum and…”

“resulting in increased cellular proliferation in an autocrine fashion.[42-44] Our data demonstrate that activated platelets could”

“endometriotic lesions are essentially wounds undergoing repeated tissue injury and repair,[13-16] and many nonendometriotic cells in the lesional microenvironment, such as platelets,[15,17] macrophages,[13,18] natural killer cells,[19,20] and nerve fibers,[21,22] are involved in facilitating the development of endomet…”

“in endometriosis, reflecting the increasing need for nutrients and oxygen as endometriotic lesions grow.[8] Conceivably, the menstrual debris, once regurgitated from the uterus to the peritoneal cavity as depicted in Sampson’s hypothesis,[3] would experience hypoxia due to a loss of blood supply.”

“[33] Tissue hypoxia is the main stimulus of EPO production.[34] HIF-1α upregulates the expression of EPO, which mediates its effects by binding to the EPO receptor (EPOR).”

“However, because endometriotic stromal cells and platelets used in this study were all derived from humans, and both platelet aggregation and hypoxia are now well documented in endometriosis,[15,17,42,56-59] we believe that platelets must play a role in hypoxia in endometriosis.”

“[34] HIF-1α upregulates the expression of EPO, which mediates its effects by binding to the EPO receptor (EPOR).[35] Hypoxia results in the increased production of EPO via the induction of the HIF-1 pathway.”

“of HIF-1α.[9,12] This may explain why endometrial debris invades and establish endometriotic foci in ectopic sites.”

“To see whether transforming growth factor-β (TGF-β) neutralization can abolish the overexpression of HIF-1α induced by activated platelets in HESC and ESCL, the cells were pretreated for 2 h with 1 μmol/L of A83-01 compound (Santa Cruz, CA, USA), which is a TGF-β receptor inhibitor, and then incubated with activated p…”

“[51] On the other hand, exposure to TGF-β1 could increase HIF-1α gene and protein expression in many cell types.[48,50,52] In this study, we found that neutralization of TGF-β1 completely abolished the HIF-1α induction by activated platelets in both HESC and ESCL, highlighting the important role of platelets in the in…”

“Hypoxia is a critical mediator of endothelial growth factors and signaling proteins during periods of metabolic stress and vascular remodeling like angiogenesis or regression,[27] most of which are mediated via transcriptional regulation by HIF.”

“the transcriptional activation of hypoxia-regulated genes, including erythropoietin (EPO), vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2),[10,11] which are”

“[36,37] EPO, a widely known growth factor in erythropoiesis, can also stimulate angiogenesis,[38] as well as tumor cell proliferation and survival.”

“Reproductive and Developmental Medicine ¦ June 25, 2019 ¦ Volume 3 ¦ Issue 2 70 is responsible for increased angiogenesis in cancers.[7] Similar to that in cancer, HIF-1α has also been shown to be overexpressed”

“[35] The expression levels of EPO,[39] VEGF, and COX-2[17] have all been reported to be elevated in endometriosis, resulting in angiogenesis, proliferation, and enhanced survival in lesional development.[35,40] We have previously shown that activated platelets can activate VEGF and COX-2 expression in HESCs;[17] in th…”

“More remarkably, activated platelets can activate HIF-1α in endometrial and endometriotic stromal cells, effectively generating a state of hypoxia [97].”

“Activated platelets can induce estrogen production in endometriotic stromal cells (97, 98), which, in turn,may induceTSLP secretion (30).”

“Of course, injury involving the vasculature may lead to estrogen production due to platelet activation [60,61], but whether hyperperistalsis can lead to such injury is unclear.”

“Yet activated platelets alone can activate HIF-1α—the master regulator of hypoxia, effectively inducing a hypoxic sate in both endometriotic and endometrial stromal cells [77].”

“我们已经知道,在月经来临前的子宫内膜处于缺血缺氧的状态,而缺氧诱导因子 1α (HIF-α)可以在缺 氧的状态下迅速积累,并且在氧气恢复后迅速下降[21]。在易患子宫内膜异位症的女性中,子宫内膜碎片 很可能就处于缺血缺氧的状态,为了建立新的血管来供应氧气和营养,HIF 调节的基因调控血管生成、 增殖、迁移、细胞凋亡和新陈代谢等多种生物过程。在这些过程中,间皮细胞和活化的巨噬细胞表达生 长因子和信号因子等多种信号物质[22]。因此,缺氧可能在血液供应之前的逆行子宫内膜存活和早期植入 的子宫内膜病变中的血管生成当中发挥重要作用[23] [24]。在一项将人类子宫内膜异位症基质细胞 (HESCs)和人类子宫内膜基质细胞(ESCL)与血小…”