Role Of Hypoxia Research Articles

Protective Role of miR-34c in Hypoxia by Activating Autophagy through BCL2 Repression.

Hypoxia leads to significant cellular stress that has diverse pathological consequences such as cardiovascular diseases and cancers. MicroRNAs (miRNAs) are one of regulators of the adaptive pathway in hypoxia. We identified a hypoxia-induced miRNA, miR-34c, that was significantly upregulated in hypoxic human umbilical cord vein endothelial cells (HUVECs) and in murine blood vessels on day 3 of hindlimb ischemia (HLI). miR-34c directly inhibited BCL2 expression, acting as a toggle switch between apoptosis and autophagy in vitro and in vivo. BCL2 repression by miR-34c activated autophagy, which was evaluated by the expression of LC3-II. Overexpression of miR-34c inhibited apoptosis in HUVEC as well as in a murine model of HLI, and increased cell viability in HUVEC. Importantly, the number of viable cells in the blood vessels following HLI was increased by miR-34c overexpression. Collectively, our findings show that miR-34c plays a protective role in hypoxia, suggesting a novel therapeutic target for hypoxic and ischemic diseases in the blood vessels.

FC 133: Knockout Of ZEB2 Ameliorates Progression of Renal Tubulointerstitial Fibrosis in a Mouse Model of Renal Ischemia-Reperfusion Injury

Abstract BACKGROUND AND AIMS Zeb2, a zinc finger E-box-binding homeobox transcription factor, reportedly regulates transforming growth factor (TGF)-β signaling pathway. However, its role in the pathogenesis of acute kidney injury (AKI) and AKI to chronic kidney disease (CKD) transition is unclear. METHOD We evaluated Zeb2 function in a bilateral renal ischemia-reperfusion injury (IRI)-induced AKI model using proximal tubule-specific Zeb2 conditional knockout (Zeb2-cKO) and wild-type (WT) mice. In Zeb2-cKO mice, plasma creatinine and blood urea nitrogen levels post-IRI were significantly lower than those in WT mice. Immunohistological analysis revealed mild tubular injury, less fibrotic changes, and reduced expression of fibrotic proteins, such as collagen type IV, α-smooth muscle actin (α-SMA), fibronectin and connective tissue growth factor (CTGF), at 3–14 days post-IRI in Zeb2-cKO mice. We also evaluated Zeb2 expression in human renal biopsy samples, including AKI to CKD patients, by immunohistological methods. RESULTS Zeb2 expression was mainly upregulated in proximal tubular cells post-IRI in WT mice. Zeb2 siRNA transfection reduced TGF-β-stimulated mRNA and protein expression of collagen type IV, α-SMA, fibronectin and CTGF in cultured renal tubular cells. Notably, patients with AKI to CKD transition showed high Zeb2 expression in renal tubules, as determined by evaluation of their renal biopsy samples. Furthermore, hypoxia and CoCl2-treatment upregulated Zeb2 promoter activity and mRNA and protein expression in cultured renal tubular epithelial cells, suggesting regulatory role of hypoxia. CONCLUSION Thus, we demonstrated Zeb2 upregulation in renal tissues in both mice and humans with AKI and showed that Zeb2 regulates fibrotic pathways in pathogenesis of AKI and AKI to CKD transition. Our findings suggest that Zeb2 blockage could serve as a potential therapeutic strategy in AKI.

Sleep Apnea and Kidney Disease: The Role of Hypoxia and Lysyl Oxidase

Study Objective/HypothesisChronic kidney disease (CKD) or progressive loss of kidney function, is a serious health condition that affects 1 in 7 adults or an estimated 37 million Americans. Epidemiological studies have linked CKD with Sleep Apnea (SA), a breathing disorder characterized by erratic breathing, and episodes of hypoxia. However, the mechanisms that underlie the association between CKD and SA are not well understood. Hypoxia Inducible Factor‐1α (HIF‐1α) is a transcription factor that regulates the body’s response to hypoxia. Lysyl oxidase and lysyl oxidase likes (LOX and LOX‐Ls) are a group of copper enzymes that are hypoxia responsive and pro‐fibrotic. We hypothesized that hypoxia in SA upregulates HIF‐1α to drive expression of LOX or LOX‐L enzymes, fibrosis, and CKD.Materials & MethodsSamples from the Sleep and Nephrology and Outcomes Research Study (SNORE), a prospective observational study of sleep disorders in veterans with CKD, were used for this study. The patients were divided into three main groups: CKD with no SA (n=14), CKD with severe SA (n=12) and healthy controls (n=13). RNA from peripheral blood mononuclear cells (PBMC) was isolated using PAXGene Blood RNA tubes (Qiagen). The RNA was then used as a template for reverse transcription, converting it into cDNA and fold changes in gene expression between groups were examined using real time PCR. Differences between groups were compared using nonparametric Mann Whitney U tests and a p‐value < 0.05 was considered statistically significant.ResultsLOX expression was lower in patients with CKD compared to healthy controls, regardless of SA (CKD with SA: 0.28 ± 0.06 (p=0.04) and CKD without SA: 0.33 ± 0.07 (p=0.09)). There were no significant differences seen in any of the LOX‐L expression (LOX‐L1 (p=0.84), LOX‐L2 (p=0.35), or LOX‐L3 (p=0.93)). Similarly, HIF‐1α was lower in patients with CKD (CKD with SA: 0.69 ± 1.0 (p=0.47) and CKD without SA: 0.46 ± 0.06 (p=0.01)). There was no statistically significant correlation between LOX and HIF‐1α (r=0.04, p=0.83).ConclusionOur results showed that HIF‐1α and LOX expression in PBMC was decreased in patients with CKD regardless of if they had SA or not. The mechanisms underlying these observations, the functional significance, and if these changes are representative of tissue LOX expression needs further studies.

MicroRNA-140-5p Suppresses Hypoxia-induced Nephrotoxicity and Renal Fibrogenesis in in vitro Conditions

Background: miR-140-5p is frequently dysregulated in different types of tumors and has been found to suppress inflammation through TLR4 in lung injury. In the current investigation, we try to decipher the possible function of miR-140-5p in hypoxia-induced nephrotoxicity and renal fibrogenesis in human renal cells. Methods: Hypoxia in HK-2 cells was produced using cobalt chloride (CoCl2). Hypoxia-induced cellular viability and apoptosis were determined by cell viability assay and ELISA-based apoptosis assay, respectively. Western blotting was carried out to measure expression levels of pro-fibrotic and apoptosis-related proteins. Result: The present study observed that upregulation of miR-140-5p significantly decreases apoptosis and increases cell viability in hypoxia challenged HK-2 cells. Furthermore, miR-140-5p over expression decreased expression of pro-apoptotic proteins like Bad and Bax and pro-fibrotic proteins like Collagen I, CTGF and fibronectin. While as, expression of anti-apoptotic protein, namely Bcl-2, was increased in hypoxia-insulted HK-2 cells. Moreover, the luciferase reporter assay confirmed that miR-140-5p targets TLR4. TLR4 knockdown prevents miR-140-5p from performing its suppressive role in hypoxia linked to apoptosis and fibrosis.

In Vitro Erythropoiesis at Different pO2 Induces Adaptations That Are Independent of Prior Systemic Exposure to Hypoxia.

Hypoxia is associated with increased erythropoietin (EPO) release to drive erythropoiesis. At high altitude, EPO levels first increase and then decrease, although erythropoiesis remains elevated at a stable level. The roles of hypoxia and related EPO adjustments are not fully understood, which has contributed to the formulation of the theory of neocytolysis. We aimed to evaluate the role of oxygen exclusively on erythropoiesis, comparing in vitro erythroid differentiation performed at atmospheric oxygen, a lower oxygen concentration (three percent oxygen) and with cultures of erythroid precursors isolated from peripheral blood after a 19-day sojourn at high altitude (3450 m). Results highlight an accelerated erythroid maturation at low oxygen and more concave morphology of reticulocytes. No differences in deformability were observed in the formed reticulocytes in the tested conditions. Moreover, hematopoietic stem and progenitor cells isolated from blood affected by hypoxia at high altitude did not result in different erythroid development, suggesting no retention of a high-altitude signature but rather an immediate adaptation to oxygen concentration. This adaptation was observed during in vitro erythropoiesis at three percent oxygen by a significantly increased glycolytic metabolic profile. These hypoxia-induced effects on in vitro erythropoiesis fail to provide an intrinsic explanation of the concept of neocytolysis.

Quantitative hypoxia mapping using a self-calibrated activatable nanoprobe

Hypoxia is a distinguished hallmark of the tumor microenvironment. Hypoxic signaling affects multiple gene expressions, resulting in tumor invasion and metastasis. Quantification of hypoxic status although challenging, can be useful for monitoring tumor development and aggressiveness. However, hypoxia-independent factors such as nonspecific binding and heterogenous probe delivery considerably influence the probe signal thereby disenabling reliable quantitative imaging in vivo. In this study, we designed a self-calibrated activatable nanoprobe Cy7-1/PG5-Cy5@LWHA that specifically detects nitroreductase activity upregulated in hypoxic tumor cells. Dual fluorescence emission of the nanoprobe enables ratiometric calibration and eliminates the target-independent interference. In orthotopic and metastatic breast cancer mouse models, Cy7-1/PG5-Cy5@LWHA demonstrated remarkable hypoxia sensing capability in vivo. Moreover, ratiometric processing provided quantitative hypoxia assessment at different tumor developmental stages and facilitated tumor burden assessment in the metastatic lymph nodes. Therefore, our study demonstrates that ratiometric imaging of Cy7-1/PG5-Cy5@LWHA can be a prospective noninvasive tool to quantitatively monitor tumor hypoxia, which would be beneficial for investigating the fundamental role of hypoxia in tumor progression and for evaluating response to novel anti-hypoxia therapeutics. Furthermore, successful detection of metastatic lymph nodes with the proposed imaging approach illustrates its potential clinical application in assessing lymph node status during surgery.Graphical

The role of hypoxia in the pathogenesis of congenital hyperplasia of blood vessels in the head and neck in children (literature review)

To date, scientists have found that stress plays an important role in the formation of congenital malformations. It can be caused by the influence of negative environmental factors on the pregnant woman or by her own diseases. One of the consequences of stress is hypoxia. It can be acute and chronic, and can have a negative impact both during pregnancy and during childbirth. They also distinguish local and general hypoxia. The consequences of the negative impact of oxygen deficiency on the embryo and fetus can manifest itself both in utero and after birth, leading to various kinds of congenital malformations, diseases, and sometimes fetal death, or increase the risk of sudden infant death syndrome. Hyperplasia of blood vessels, the so-called children’s hemangiomas, develops both in utero, especially with chronic fetal hypoxia, and during childbirth. It develops due to insufficient blood supply and oxygen deficiency in various parts of the body, most often in the head and neck. In an embryo under conditions of hypoxia, tachycardia develops – with an increase in heart rate and, if it is ineffective, local vasodilation occurs. Only then, under the condition of continuing hypoxia, does an increase in the number of blood vessels develop. This often leads to the formation of hyperplasia of the blood vessels, the so-called children’s hemangiomas.This pathology is quite common, especially among fair-skinned children, which makes its study, in particular the factors that cause this pathology, relevant today.

The possible role of hypoxia in the affected tissue of relapsed clubfoot

Our aim was to study the expression of hypoxia-related proteins as a possible regulatory pathway in the contracted side tissue of relapsed clubfoot. We compared the expression of hypoxia-related proteins in the tissue of the contracted (medial) side of relapsed clubfoot, and in the tissue of the non-contracted (lateral) side of relapsed clubfoot. Tissue samples from ten patients were analyzed by immunohistochemistry and image analysis, Real-time PCR and Mass Spectrometry to evaluate the differences in protein composition and gene expression. We found a significant increase in the levels of smooth muscle actin, transforming growth factor-beta, hypoxia-inducible factor 1 alpha, lysyl oxidase, lysyl oxidase-like 2, tenascin C, matrix metalloproteinase-2, matrix metalloproteinase-9, fibronectin, collagen types III and VI, hemoglobin subunit alpha and hemoglobin subunit beta, and an overexpression of ACTA2, FN1, TGFB1, HIF1A and MMP2 genes in the contracted medial side tissue of clubfoot. In the affected tissue, we have identified an increase in the level of hypoxia-related proteins, together with an overexpression of corresponding genes. Our results suggest that the hypoxia-associated pathway is potentially a factor contributing to the etiology of clubfoot relapses, as it stimulates both angioproliferation and fibroproliferation, which are considered to be key factors in the progression and development of relapses.

Thyroid hormone increases oxygen metabolism causing intrarenal tissue hypoxia; a pathway to kidney disease.

The proposed mechanisms for the development of nephropathy are many, complex and often overlapping. Although recent literature strongly supports a role of kidney hypoxia as an independent pathway to nephropathy, the evidence remains inconclusive since the role of hypoxia is difficult to differentiate from confounding factors such as hyperglycemia, hypertension and oxidative stress. By increasing kidney oxygen consumption using triiodothyronine (T3) and, thus, avoiding these confounding factors, the aim of the present study was to investigate renal hypoxia per se as a causal pathway for the development of nephropathy. Healthy Sprague-Dawley rats were treated with T3 (10 μg/kg/day) and the angiotensin II AT1-receptor antagonist candesartan (1 mg/kg in drinking water) to eliminate effects of T3-induced renin release; and compared to a candesartan treated control group. After 7 weeks of treatment in vivo kidney function, oxygen metabolism and mitochondrial function were evaluated. T3 did not affect glomerular filtration rate or renal blood flow, but increased total kidney oxygen consumption resulting in cortical hypoxia. Nephropathy, demonstrated as albuminuria and tubulointerstitial fibrosis, developed in T3-treated animals. Mitochondria uncoupling mediated by uncoupling protein 2 and the adenosine nucleotide transporter was demonstrated as a mechanism causing the increased kidney oxygen consumption. Importantly, blood glucose levels, mean arterial blood pressure and oxidative stress levels were not affected by T3. In conclusion, the present study provides further evidence for increased kidney oxygen consumption causing intrarenal tissue hypoxia, as a causal pathway for development of nephropathy.

Role of Hypoxia in the Interferon Response.

In solid tumors, as the tumor grows and the disease progresses, hypoxic regions are often generated, but in contrast to most normal cells which cannot survive under these conditions, tumour cells adapt to hypoxia by HIF-driven mechanisms. Hypoxia can further promote cancer development by generating an immunosuppressive environment within the tumour mass, which allows tumour cells to escape the immune system recognition. This is achieved by recruiting immunosuppressive cells and by upregulating molecules which block immune cell activation. Hypoxia can also confer resistance to antitumor therapies by inducing the expression of membrane proteins that increase drug efflux or by inhibiting the apoptosis of treated cells. In addition, tumor cells require an active interferon (IFN) signalling pathway for the success of many anticancer therapies, such as radiotherapy or chemotherapy. Therefore, hypoxic effects on this pathway needs to be addressed for a successful treatment.

The Role of Hypoxia in Endometrial Cancer.

Endometrial cancer represents the most frequent neoplasia from the corpus uteri and comprises the 14th leading cause of death in women worldwide. Risk factors that contribute to the disease include early menarche, late menopause, nulliparity, and menopausal hormone use, as well as hypertension and obesity comorbidities. The clinical effectiveness of chemotherapy is variable, suggesting that novel molecular targeted therapies against specific cellular processes associated with the maintenance of cancer cell survival and therapy resistance ameliorate the rates of success in endometrial cancer treatment. In the course of tumor growth, cancer cells must adapt to decreased oxygen availability in the microenvironment by upregulation of hypoxia-inducible factors, which orchestrate the activation of a transcriptional program leading to cell survival. During this adaptative process, the hypoxic cancer cells may acquire invasive and metastatic properties as well as increased cell proliferation and resistance to chemotherapy, enhanced angiogenesis, vasculogenic mimicry, and maintenance of cancer cell stemness, which contribute to more aggressive cancer phenotypes. Several studies have shown that hypoxia-inducible factor 1 alpha (HIF-1α) protein is aberrantly overexpressed in many solid tumors of the breast, prostate, ovarian, bladder, colon, brain, and pancreas. Thus, it has been considered an important therapeutic target. Here, we reviewed the current knowledge of the relevant roles of cellular hypoxia mechanisms and HIF-1α functions in diverse processes associated with endometrial cancer progression. In addition, we also summarize the role of microRNAs in the posttranscriptional regulation of protein-encoding genes involved in the hypoxia response in endometrial cancer. Finally, we pointed out the need for urgent targeted therapies to impair the cellular processes activated by hypoxia in the tumor microenvironment.

Моніторинг вмісту в крові карбоксигемоглобіну для оцінки тяжкості травматичного шоку та реперфузійних ушкоджень (аналітичний огляд з результатами власних спостережень)

Монооксид вуглецю — природний метаболіт організму. В організмі СО утворюється в процесі роботи ферменту гемоксигенази 1 та 2 із зруйнованого гемоглобіну. Цей процес зумовлює утворення деякої кількості карбоксигемоглобіну у здорових осіб, навіть якщо СО не надходить до організму ззовні в процесі дихання. СО виконує функції сигнальної молекули, модулюючи стан тонусу серцево-судинної системи, пригнічує та сприяє зворотному розвитку порушень, що викликані запальною відповіддю, та може відігравати важливу роль як потенційний терапевтичний агент. З іншого боку, СО при взаємодії з гемоглобіном утворює карбоксигемоглобін та витісняє кисень із зв’язки з гемоглобіном, що веде до неспроможності доставки кисню тканинам. Окрім цього, СО також зв’язується із міоглобіном та мітохондріальною цитохромоксидазою. Тривала присутність у крові значної кількості СО викликає серйозні ушкодження міокарда та центральної нервової системи. Отже, надмірна ендогенна продукція СО та надмірне утворення карбоксигемоглобіну можуть відігравати значну роль у тканинному пошкодженні та формуванні поліорганної дисфункції. Окрім гему, що звільнюється при руйнуванні гемоглобіну, джерелом продукції ендогенного СО та, у свою чергу, карбоксигемоглобіну можуть бути компоненти зруйнованих клітинних мембран та мітохондріальні ферменти, що містять гем. Клітинні ушкодження, що мають місце в умовах травматичного шоку, наслідки ішемії/реперфузії, геморагічне просочення тканин, гемотрансфузії та інтенсивне утворення агресивних вільних радикалів ведуть до зазначених подій. На сьогодні більшість дослідників розглядає продукцію СО та карбоксигемоглобіну при критичних станах як компенсаторний механізм, що забезпечує цитопротекцію та зростання виживаності хворих. Ми вивчили результати досліджень, що стосуються оцінки інтенсивності продукції СО, вмісту в крові карбоксигемоглобіну та вмісту СО в повітрі, що видихається, у пацієнтів в критичних станах та порівняли ці результати із даними власних спостережень. В іноземних джерелах наведено концентрації карбоксигемоглобіну в крові, що в більшості випадків не перевищували 4 %. У нашому дослідженні вивчались пацієнти із політравмою та крововтратою на ранньому госпітальному етапі. Оцінювалися показники центральної гемодинаміки, а також сатурація капілярної крові киснем, перфузійний індекс та вміст у крові карбоксигемоглобіну за допомогою технології компанії «Masimo». Усі постраждалі надходили до клініки з нормальним вмістом карбоксигемоглобіну в крові. Патологічне зростання концентрації карбоксигемоглобіну спостерігалося в процесі реперфузії. Швидка рідинна ресусцитація, застосування гіпертонічних розчинів та адреналіну сприяли зростанню артеріального тиску, перфузійного індексу та концентрації карбоксигемоглобіну. Наступне за реперфузією зростання концентрації в крові карбоксигемоглобіну було тим більшим, чим більш тяжким був перебіг шоку. Реінфузія крові також сприяла збільшенню концентрації карбоксигемоглобіну в крові. Високі показники концентрації карбоксигемоглобіну в крові постраждалих із травматичним шоком у період реперфузії закономірно викликають питання про його роль у формуванні мітохондріальної дисфункції при травматичній хворобі.

Obesity, Adipose Tissue, and Inflammation Answered in Questions.

Background. Obesity is a global health problem of epidemic proportions, which is characterized by increased adipose tissue (AT) mass and significant repercussions in different body apparati and systems. AT is a special connective tissue, which contains several types of cells, in addition to adipocytes, and is a highly active endocrine and immune organ, which directly modulates many processes, including energy balance, metabolism, and inflammation. Summary. In this paper, the authors list and attempt to answer in a brief and simple way several questions regarding the complex relationships between obesity, adipose tissue, and inflammation, with the objective to provide an easy way to understand the main changes that occur in this pathological state. The questions are the following: Is adipose tissue only made up of adipocytes? Are adipocytes just a reservoir of free fatty acids? Do different types of fatty tissue exist? If so, which types? Can we further subcategorize the types of adipose tissue? Is it possible to form new adipocytes during adulthood? What is the role of inflammation? What is the role of macrophages? Are macrophages central mediators of obesity-induced adipose tissue inflammation and insulin resistance? What causes macrophage infiltration into adipose tissue? What is the role of hypoxia in AT alterations? Is there cross talk between adipocytes and immune cells? What other changes occur in AT in obesity? Does metabolically healthy obesity really exist? Is this a benign condition? Key messages. Obesity is a complex disease with numerous metabolic consequences, which are mainly the result of dysfunction that occurs in the adipose tissue of patients with this pathology. Understanding the pathophysiology of AT and the changes that occur in obesity would contribute to a better approach to patients with obesity, with the inherent medical implications that could result from this.

Microenvironment-driven intratumoral heterogeneity in head and neck cancers: clinical challenges and opportunities for precision medicine.

Squamous cell carcinoma of the head and neck (SCCHN) is among the most prevalent cancer types worldwide. Despite multimodal therapeutic approaches that include surgical resection, radiation therapy or concurrent chemoradiation, targeted therapy and immunotherapy, SCCHN is still associated with a poor prognosis for patients with locally advanced or recurrent/metastatic (R/M) diseases. Although next-generation sequencing data from thousands of SCCHN patients have provided a comprehensive landscape of the somatic genomic alterations in this disease, genomic-based precision medicine is not implemented yet in routine clinical use since no satisfactory genetic biomarker has been identified for diagnosis, patient outcome prediction and selection of tailored therapeutic options. The lack of significant improvement in SCCHN patient survival over the last decades stresses the need for reliable predictive biomarkers and new therapeutic strategies for personalized clinical management of SCCHN patients. Targeting the SCCHN-associated microenvironment or the interaction of the latter with cancer cells may represent such paradigm shift in the development of new strategies to treat SCCHN patients, as exemplified by the recent implementation of immune checkpoint inhibitors to improve clinical outcomes by increasing anti-tumor immune responses in SCCHN patients. Several clinical trials are in progress in SCCHN patients to evaluate the activity of monoclonal antibodies and small-molecule inhibitors targeting the tumor microenvironment (TME) at different treatment settings, including combinations with adjuvant surgery, radiation therapy and chemotherapy. This review describes the current knowledge about the influence of the TME on intratumoral heterogeneity and clinical relapse in human SCCHN patients. More precisely, the role of hypoxia as well as the presence of non-cancer cells (e.g. cancer-associated fibroblasts and immune cells) on therapy response of SCCHN cells is highlighted. We also discuss relevant (pre)clinical models that may help integrate the microenvironment-tumor cell interplay in translational research studies for SCCHN. Finally, this review explores potential therapeutic strategies that may exploit the crosstalk between TME and SCCHN cells in order to implement fundamental changes in the tumor treatment paradigm of patients with locally advanced or R/M SCCHN.

Role of Hypoxia on Growth and Differentiation of Human Adipose Derived Stem Cells Grown on Silk Fibroin Scaffold Induced by Platelet Rich Plasma

Previous research has proven that 10% platelet-rich plasma (PRP) can enhance growth and differentiation of human adipose derived stem cells (hADSC) grown on silk fibroin scaffold into chondrocytes. A low oxygen concentration (hypoxia) condition is an important factor that potentially affects the ability of hADSC to grow and differentiate. The objective of this research was to analyze the difference in growth and differentiation capacity of hADSC grown on salt leached silk fibroin scaffold supplemented by 10% PRP under normoxic and hypoxic conditions. The growth capacity of the hADSC was determined by MTT assay and differentiation was tested using glycosaminoglycan (GAG) content analysis, while chondrocyte markers were visualized with the immunocytochemistry (ICC) method. This research observed hADSC proliferation under normoxic and hypoxic conditions for 21 days. Visualization of type 2 collagen showed that it was more abundant under hypoxia compared to normoxia. HIF-1α was only detected in the hADSC cultured in hypoxic conditions. In conclusion, culture under hypoxic conditions increases the capacity of hADSC to grow and differentiate into chondrocytes. This is the first study that has shown that hypoxia is able to enhance the proliferation and differentiation of hADSC grown on 3D salt leached silk fibroin scaffold supplemented by 10% PRP.

Regulation of citrulline synthesis in human enterocytes: Role of hypoxia and inflammation

AbstractIntensive care unit patients and chronic airway inflammatory disease are characterized by chronic systemic hypoxia and inflammation inducing a decrease in nitric oxide release due to impaired l‐arginine (ARG) homeostasis. As ARG is synthesized from circulating l‐citrulline (CIT), an alteration of CIT production in small intestine by ornithine carbamoyltransferase could be involved. Here, we posit that hypoxia and/or inflammation has effects on ornithine carbamoyltransferase regulation in enterocytes. A duodenal explant incubation model was used. Biopsy specimens taken from 25 selected patients were incubated for 6 h in 4 groups: control, inflammation, hypoxia, and hypoxia + inflammation. At the end of the incubation period, we measured CIT concentration in culture media, ornithine carbamoyltransferase activity, ornithine carbamoyltransferase protein and gene expression, protein expression of enzymes involved in the CIT production pathway, and expression of energy status proteins. Inflammation and/or hypoxia conditions did not affect CIT production. Ornithine carbamoyltransferase activity was increased in hypoxia conditions (p = 0.023). Expression of enzymes implicated in the CIT crossroads pathway and enzymes reflecting energy status variation was not affected by inflammation and hypoxia. Data sets were pooled to evaluate the variability of the four quartiles for each parameter. CIT production was found to increase over the quartiles whereas other parameters remained stable. Our results showed that intestinal CIT production is preserved during inflammation and/or hypoxia, thus confirming the significance of this metabolic pathway. This suggests that the CIT deficiency observed in clinical hypercatabolic states could be a consequence of high utilization for ARG synthesis.

Carotid Body Inflammation: Role in Hypoxia and in the Anti-inflammatory Reflex.

Emergent evidence indicates that the carotid body (CB) chemoreceptor may sense systemic inflammatory molecules and is an afferent arm of the anti-inflammatory reflex. Moreover, a proinflammatory milieu within the CB is involved in the enhanced CB chemosensory responsiveness to oxygen following sustained and intermittent hypoxia. In this review, we focus on the physiopathological participation of CBs in inflammatory diseases, such as sepsis and intermittent hypoxia.

Kidney Cancer and Chronic Kidney Disease: Too Close for Comfort.

Kidney cancer and chronic kidney disease are two renal pathologies with very different clinical management strategies and therapeutical options. Nonetheless, the cellular and molecular mechanisms underlying both conditions are closely related. Renal physiology is adapted to operate with a limited oxygen supply, making the kidney remarkably equipped to respond to hypoxia. This tightly regulated response mechanism is at the heart of kidney cancer, leading to the onset of malignant cellular phenotypes. Although elusive, the role of hypoxia in chronic kidney diseases is emerging as related to fibrosis, a pivotal factor in decaying renal function. The present review offers a perspective on the common biological traits shared between kidney cancer and chronic kidney disease and the available and prospective therapies for both conditions.

Abstract 11266: Murine Adult Epicardium Requires Hypoxia for Progenitor and Multipotency Ability

Introduction: The epicardium is a source of the coronary vasculature and stroma during heart development. Although quiescent in the physiological adult heart, increasing evidences indicate the potential epicardium activation and differentiation into its progeny after cardiac injury; however, this remains debated. Hypothesis: We hypothesize that in vivo hypoxia exposure can mimic the embryonic cardiac profile and prime the adult epicardial progenitor cell to a more immature profile. Methods: Perinatal and adult BL6 and Pw1 nLacz hearts were used to track the expression of PW1 - progenitor cell marker - together with cell surface proteins. In vivo hypoxia (10% O 2 ) exposure was used to stimulate the adult heart. Histology, protein expression profiles and single cell analysis were assessed. Freshly FACS isolated Gp38 + PW1 + epicardial cells were cultured to determine their progenitor cell potential (clonogenicity, self-renewal and cell fate potential). Results: Here, we report that PW1 expression decreases during postnatal life, but is maintained in the cardiac hypoxic niche epicardium and subepicardium. Adult mice exhibit increased PW1 expression in epicardial/subepicardial cells and endothelial cells in response to hypoxia. The epicardium and subepicardium are activated to undergo cell proliferation and re-express a subset of embryonic genes in response to hypoxia. We established a new in vitro model to study purified PW1 + /Gp38 + epicardial cells, and we found properties of clonogenicity, self-renewal and multipotency (fibroblast, smooth muscle and endothelial cells) at single cell level in the developing epicardial cells. Cell fate potential towards an endothelial profile is dependent upon low levels of oxygen, and the in vitro ability to grow in culture is restore after in vivo priming of the adult heart. Conclusions: In conclusion our data support that the resident PW1 + /Gp38 + epicardial cells are a reminiscent progenitor population in adult mammalian heart that can be reactivated by exposure to hypoxia, highlighting the potential therapeutic role of hypoxia in regenerative medicine.

The m6A methyltransferase METTL3 promotes hypoxic pulmonary arterial hypertension via targeting PTEN

Abstract Background N6-methyladenosine (m6A) is the most prevalent internal RNA modification in mammal mRNAs. Accumulating evidence has indicated the crucial role of m6A modification in cardiovascular diseases including cardiac hypertrophy, heart failure, ischemic heart disease, vascular calcification, restenosis, and aortic aneurysm. However, the role of m6A methylation in the occurrence and development of hypoxic pulmonary hypertension (HPH) remains largely unknown. Purpose The present study aims to explore the role of key transferase METTL3, in the development of HPH. Methods Hypoxic rat models and pulmonary artery smooth muscle cells (PASMCs) and were used to research the METTL3-mediated m6A in HPH in vivo and in vitro. CCK-8, EdU, PCNA, transwell and TUNEL assay were performed to evaluate the proliferation, migration and apoptosis rates of PASMCs. m6A RNA Methylation Quantification Kit and m6A-qPCR were utilized to measure the total m6A level and m6A-PTEN mRNA expression. RNA immunoprecipitation and RNA pull down were used to detect the interaction between METTL3 and PTEN mRNA. The half-life of mRNA was detected through actinomycin D assay. Results Both METTL3 mRNA and protein were found abnormally upregulated in pulmonary arteries of HPH rats and hypoxia induced PASMCs. Furthermore, downregulation of METTL3 attenuated PASMCs proliferation and migration exposed to hypoxia. In addition, m6A binding protein YTHDF2 was found significantly increased in HPH group in vivo and in vitro. Mechanistically, YTHDF2 recognized METTL3 mediated m6A-PTEN mRNA and promoted the degradation of PTEN. Decreased PTEN led to over-proliferation of PASMCs through activation of PI3K/Akt signaling pathway. Conclusion METTL3/YTHDF2/PTEN axis exerts a significant role in hypoxia induced PASMCs proliferation, providing a novel therapeutic target for HPH. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Natural Science Foundation of China Figure 1