Contribution of oxidative stress to endothelial dysfunction in hereditary hemorrhagic telangiectasia

Assessment of soluble thrombomodulin and soluble endoglin as endothelial dysfunction biomarkers in seriously ill surgical septic patients: correlation with organ dysfunction and disease severity

BACKGROUND

Sepsis, a complex condition characterized by dysregulated immune response and organ dysfunction, is a leading cause of mortality in ICU patients. Current diagnostic and prognostic approaches primarily rely on non-specific biomarkers and illness severity scores, despite early endothelial activation being a key feature of sepsis. This study aimed to evaluate the levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients and explore their association with organ dysfunction and disease severity.

METHODOLOGY

A case control study was conducted from March 2022 to November 2022, involving seriously ill septic surgical patients. Baseline clinical and laboratory data were collected within 24 h of admission to the Surgical Intensive Care Unit. This included information such as age, sex, hemodynamic parameters, blood chemistry, SOFA score, qSOFA score, and APACHE-II score. A proforma was filled out to record these details. The outcome of each patient was noted at the time of discharge.

RESULTS

The study found significantly elevated levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients. The RTqPCR analysis revealed a positive correlation between soluble thrombomodulin and soluble endoglin levels with the qSOFA score, as well as, there was a positive association between RTqPCR soluble thrombomodulin and the SOFA score. These findings indicate a correlation between these biomarkers and organ dysfunction and disease severity.

CONCLUSION

The study concludes that elevated levels of soluble thrombomodulin and soluble endoglin can serve as endothelial biomarkers for early diagnosis and prognostication in seriously ill surgical septic patients.

Oxidative stress-induced MMP- and γ-secretase-dependent VE-cadherin processing is modulated by the proteasome and BMP9/10

Classical cadherins, including vascular endothelial (VE)-cadherin, are targeted by matrix metalloproteinases (MMPs) and γ-secretase during adherens junction (AJ) disassembly, a mechanism that might have relevance for endothelial cell (EC) integrity and vascular homeostasis. Here, we show that oxidative stress triggered by H₂O₂ exposure induced efficient VE-cadherin proteolysis by MMPs and γ-secretase in human umbilical endothelial cells (HUVECs). The cytoplasmic domain of VE-cadherin produced by γ-secretase, VE-Cad/CTF2-a fragment that has eluded identification so far-could readily be detected after H₂O₂ treatment. VE-Cad/CTF2, released into the cytosol, was tightly regulated by proteasomal degradation and was sequentially produced from an ADAM10/17-generated C-terminal fragment, VE-Cad/CTF1. Interestingly, BMP9 and BMP10, two circulating ligands critically involved in vascular maintenance, significantly reduced VE-Cad/CTF2 levels during H₂O₂ challenge, as well as mitigated H₂O₂-mediated actin cytoskeleton disassembly during VE-cadherin processing. Notably, BMP9/10 pretreatments efficiently reduced apoptosis induced by H₂O₂, favoring endothelial cell recovery. Thus, oxidative stress is a trigger of MMP- and γ-secretase-mediated endoproteolysis of VE-cadherin and AJ disassembly from the cytoskeleton in ECs, a mechanism that is negatively controlled by the EC quiescence factors, BMP9 and BMP10.

The Role of Endothelial Cells in the Onset, Development and Modulation of Vein Graft Disease

Endothelial cells comprise the intimal layer of the vasculature, playing a crucial role in facilitating and regulating aspects such nutrient transport, vascular homeostasis, and inflammatory response. Given the importance of these cells in maintaining a healthy haemodynamic environment, dysfunction of the endothelium is central to a host of vascular diseases and is a key predictor of cardiovascular risk. Of note, endothelial dysfunction is believed to be a key driver for vein graft disease-a pathology in which vein grafts utilised in coronary artery bypass graft surgery develop intimal hyperplasia and accelerated atherosclerosis, resulting in poor long-term patency rates. Activation and denudation of the endothelium following surgical trauma and implantation of the graft encourage a host of immune, inflammatory, and cellular differentiation responses that risk driving the graft to failure. This review aims to provide an overview of the current working knowledge regarding the role of endothelial cells in the onset, development, and modulation of vein graft disease, as well as addressing current surgical and medical management approaches which aim to beneficially modulate endothelial function and improve patient outcomes.

Photodistributed eruptive telangiectasias: an uncommon adverse drug reaction. A retrospective case series

Drug-induced photodistributed telangiectasia (PT) is cutaneous side effects resulting from the interaction of ultraviolet (UV) radiation with pharmacotherapy. Reports of PT in literature are scarce. We report twenty-five cases of drug-induced photodistributed telangiectasias, highlighting the potential relationship between the onset of skin lesions, drug-intake and photo-exposure. We alert practitioners that telangiectasia is a possible dermatological phototoxic side-effect to many drugs.

Drug-Induced Photosensitivity: Clinical Types of Phototoxicity and Photoallergy and Pathogenetic Mechanisms

Drug-induced photosensitivity (DIP) is a common cutaneous adverse drug reaction, resulting from the interaction of ultraviolet radiations, mostly ultraviolet A, with drugs. DIP includes phototoxicity and photoallergy. A phototoxic reaction is obtained when topical and systemic drugs or their metabolites absorb light inducing a direct cellular damage, while a photoallergic reaction takes place when the interaction between drugs and ultraviolet radiations causes an immune cutaneous response. Clinically, phototoxicity is immediate and appears as an exaggerated sunburn, whereas photoallergy is a delayed eczematous reaction. DIP may show several clinical subtypes. In this mini-review we report the pathogenetic mechanisms and causative drugs of DIP. We offer a detailed description of DIP clinical features in its classical and unusual subtypes, such as hyperpigmentation/dyschromia, pseudoporphyria, photo-onycolysis, eruptive teleangiectasia, pellagra-like reaction, lichenoid reaction, photodistributed erythema multiforme and subacute/chronic cutaneous lupus erythematosus. We described how physicians may early recognize and manage DIP, including diagnostic tests to rule out similar conditions. We made suggestions on how to improve sun exposure behaviors of patients at risk of DIP by means of an aware use of sunscreens, protective clothing and recent technologic tools. We highlighted the lack of sun safety programs addressed to patients at risk of DIP, who need a formal education about their condition.

Kinetics of Biomarkers of Oxidative Stress in Septic Shock: A Pilot Study

Septic shock is a major cause of mortality in ICU patients, its pathophysiology is complex and not properly understood. Oxidative stress seems to be one of the most important mechanisms of shock progression to multiple organ failure. In the present pilot study, we have analysed eight oxidative-stress-related biomarkers in seven consecutive time points (i.e., the first seven days) in 21 septic shock patients admitted to the ICU. Our objective was to describe the kinetics of four biomarkers related to pro-oxidative processes (nitrite/nitrate, malondialdehyde, 8-oxo-2′-deoxyguanosine, soluble endoglin) compared to four biomarkers of antioxidant processes (the ferric reducing ability of plasma, superoxide dismutase, asymmetric dimethylarginine, mid-regional pro-adrenomedullin) and four inflammatory biomarkers (CRP, IL-6, IL-10 and neopterin). Furthermore, we analysed each biomarker’s ability to predict mortality at the time of admission and 12 h after admission. Although a small number of study subjects were recruited, we have identified four promising molecules for further investigation: soluble endoglin, superoxide dismutase, asymmetric dimethylarginine and neopterin.

The wHole Story About Fenestrations in LSEC

The porosity of liver sinusoidal endothelial cells (LSEC) ensures bidirectional passive transport of lipoproteins, drugs and solutes between the liver capillaries and the liver parenchyma. This porosity is realized via fenestrations - transcellular pores with diameters in the range of 50-300 nm - typically grouped together in sieve plates. Aging and several liver disorders severely reduce LSEC porosity, decreasing their filtration properties. Over the years, a variety of drugs, stimulants, and toxins have been investigated in the context of altered diameter or frequency of fenestrations. In fact, any change in the porosity, connected with the change in number and/or size of fenestrations is reflected in the overall liver-vascular system crosstalk. Recently, several commonly used medicines have been proposed to have a beneficial effect on LSEC re-fenestration in aging. These findings may be important for the aging populations of the world. In this review we collate the literature on medicines, recreational drugs, hormones and laboratory tools (including toxins) where the effect LSEC morphology was quantitatively analyzed. Moreover, different experimental models of liver pathology are discussed in the context of fenestrations. The second part of this review covers the cellular mechanisms of action to enable physicians and researchers to predict the effect of newly developed drugs on LSEC porosity. To achieve this, we discuss four existing hypotheses of regulation of fenestrations. Finally, we provide a summary of the cellular mechanisms which are demonstrated to tune the porosity of LSEC.

Neurovascular inflammation in the pathogenesis of brain arteriovenous malformations

Brain arteriovenous malformations (bAVM) arise as congenital or sporadic focal lesions with a significant risk for intracerebral hemorrhage (ICH). A wide range of interindividual differences is present in the onset, progression, and severity of bAVM. A growing body of gene expression and polymorphism-based research studies support the involvement of localized inflammation in bAVM disease progression and rupture. In this review article, we analyze the altered responses of neural, vascular, and immune cell types that contribute to the inflammatory process, which exacerbates the pathophysiological progression of vascular dysmorphogenesis in bAVM lesions. The cumulative effect of inflammation in bAVM development is orchestrated by various genetic moderators and inflammatory mediators. We also discuss the potential therapies for the treatment of brain AVM by targeting the inflammatory processes and mediators. Elucidating the precise role of inflammation in the bAVM growth and hemorrhage would open novel avenues for noninvasive and effectual causal therapy that may complement the current therapeutic strategies.

Potential Second-Hits in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder that presents with telangiectases in skin and mucosae, and arteriovenous malformations (AVMs) in internal organs such as lungs, liver, and brain. Mutations in ENG (endoglin), ACVRL1 (ALK1), and MADH4 (Smad4) genes account for over 95% of HHT. Localized telangiectases and AVMs are present in different organs, with frequencies which differ among affected individuals. By itself, HHT gene heterozygosity does not account for the focal nature and varying presentation of the vascular lesions leading to the hypothesis of a “second-hit” that triggers the lesions. Accumulating research has identified a variety of triggers that may synergize with HHT gene heterozygosity to generate the vascular lesions. Among the postulated second-hits are: mechanical trauma, light, inflammation, vascular injury, angiogenic stimuli, shear stress, modifier genes, and somatic mutations in the wildtype HHT gene allele. The aim of this review is to summarize these triggers, as well as the functional mechanisms involved.

Neuroprotective effects of zafirlukast, piracetam and their combination on L-Methionine-induced vascular dementia in rats

Vascular dementia is considered a vascular cognitive impairment disease caused by neuronal degeneration in the brain. Several studies have supported the hypothesis that oxidative stress and endothelial dysfunction are the main pathogenic factors in vascular dementia. This current study aims to determine the possible neuroprotective effects of zafirlukast, piracetam and the combination of piracetam and zafirlukast on L-methionine-induced vascular dementia in rats. Male Wistar albino rats were divided into five groups. Group I was the normal control, and group II received L-methionine (1700 mg/kg, P.O.) for 32 days. The remaining groups received zafirlukast (20 mg/kg, P.O.), piracetam (600 mg/kg, P.O.) or their combination (zafirlukast 20 mg/kg + piracetam 600 mg/kg, P.O.) for 32 days after L-methionine administration. Afterwards, the cognitive and memory performances of the rats were investigated using the novel object recognition (NOR) test; rats were then sacrificed for histopathological and biochemical analyses. L-methionine-induced vascular dementia altered rats' behaviours and the brain contents of different neurotransmitters and acetylcholinesterase activity while increasing levels of oxidative stress and causing notable histopathological alterations in brain tissues. The treatment of vascular dementia with zafirlukast and the combination improved neurochemical, behavioural and histological alterations to a comparable level to those of piracetam. Thus, zafirlukast, piracetam and the combination of both drugs can be considered as potential therapeutic strategies for the treatment of vascular dementia induced by L-methionine. To the best of our knowledge, this study is the first to explore the neuroprotective effects of zafirlukast and piracetam on L-methionine-induced vascular dementia.

Computational analysis of interactions of oxidative stress and tetrahydrobiopterin reveals instability in eNOS coupling

In cardiovascular and neurovascular diseases, an increase in oxidative stress and endothelial dysfunction has been reported. There is a reduction in tetrahydrobiopterin (BH4), which is a cofactor for the endothelial nitric oxide synthase (eNOS), resulting in eNOS uncoupling. Studies of the enhancement of BH4 availability have reported mixed results for improvement in endothelial dysfunction. Our understanding of the complex interactions of eNOS uncoupling, oxidative stress and BH4 availability is not complete and a quantitative understanding of these interactions is required. In the present study, we developed a computational model for eNOS uncoupling that considers the temporal changes in biopterin ratio in the oxidative stress conditions. Using the model, we studied the effects of cellular oxidative stress (Qsupcell) representing the non-eNOS based oxidative stress sources and BH4 synthesis (QBH4) on eNOS NO production and biopterin ratio (BH4/total biopterins (TBP)). Model results showed that oxidative stress levels from 0.01 to 1nM·s-1 did not affect eNOS NO production and eNOS remained in coupled state. When the Qsupcell increased above 1nM·s-1, the eNOS coupling and NO production transitioned to an oscillatory state. Oxidative stress levels dynamically changed the biopterin ratio. When Qsupcell increased from 1 to 100nM·s-1, the endothelial cell NO production, TBP levels and biopterin ratio reduced significantly from 26.5 to 2nM·s-1, 3.75 to 0.002μM and 0.99 to 0.25, respectively. For an increase in BH4 synthesis, the improvement in NO production rate and BH4 levels were dependent on the extent of cellular oxidative stress. However, a 10-fold increase in QBH4 at higher oxidative stresses did not restore the NO-production rate and the biopterin ratio. Our mechanistic analysis reveals that a combination of enhancing tetrahydrobiopterin level with a reduction in cellular oxidative stress may result in significant improvement in endothelial dysfunction.

The LDL/HDL ratio and atherosclerosis in ankylosing spondylitis

OBJECTIVES

In ankylosing spondylitis (AS) patients, cardiac and vascular involvement may manifest as atherosclerosis and coronary artery disease. Systemic inflammation, oxidative stress, increased low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol constitute a significant risk for atherosclerosis. This study investigated the relationship between carotid intima-media thickness (CIMT), LDL/HDL ratio, total oxidant status (TOS; an indicator of oxidative stress) and ischemic modified albumin (IMA; an ischemic marker in AS patients).

PATIENTS AND METHODS

Sixty AS patients were diagnosed using the Modified New York Criteria; 54 age- and gender-matched participants were included as controls. CIMT, LDL/HDL ratio, TOS and IMA were measured using the most appropriate methods.

RESULTS

IMA was higher in AS patients compared to controls (p < 0.0001). TOS was also increased in AS patients (p = 0.005); as was CIMT (p < 0.0001). The LDL/HDL ratio was also greater in AS patients compared to controls (p = 0.047). A positive correlation was found between CIMT and LDL/HDL ratio among AS patients.

CONCLUSION

Elevated CIMT, IMA and TOS levels suggest an increased risk of atherosclerotic heart disease in AS patients. The LDL/HDL ratio was higher in AS patients compared to controls, and there was a correlation between LDL/HDL ratio and CIMT, albeit statistically weak. Therefore, the LDL/HDL ratio is not a reliable marker to predict atherosclerotic heart disease in AS patients.

Endoglin and alk1 as therapeutic targets for hereditary hemorrhagic telangiectasia

INTRODUCTION

Hereditary Haemorrhagic Telangiectasia (HHT) is as an autosomal dominant trait characterized by frequent nose bleeds, mucocutaneous telangiectases, arteriovenous malformations (AVMs) of the lung, liver and brain, and gastrointestinal bleedings due to telangiectases. HHT is originated by mutations in genes whose encoded proteins are involved in the transforming growth factor β (TGF-β) family signalling of vascular endothelial cells. In spite of the great advances in the diagnosis as well as in the molecular, cellular and animal models of HHT, the current treatments remain just at the palliative level. Areas covered: Pathogenic mutations in genes coding for the TGF-β receptors endoglin (ENG) (HHT1) or the activin receptor-like kinase-1 (ACVRL1 or ALK1) (HHT2), are responsible for more than 80% of patients with HHT. Therefore, ENG and ALK1 are the main potential therapeutic targets for HHT and the focus of this review. The current status of the preclinical and clinical studies, including the anti-angiogenic strategy, have been addressed. Expert opinion: Endoglin and ALK1 are attractive therapeutic targets in HHT. Because haploinsufficiency is the pathogenic mechanism in HHT, several therapeutic approaches able to enhance protein expression and/or function of endoglin and ALK1 are keys to find novel and efficient treatments for the disease.

Potential New Non-Invasive Therapy Using Artificial Oxygen Carriers for Pre-Eclampsia

The molecular mechanisms of pre-eclampsia are being increasingly clarified in animals and humans. With the uncovering of these mechanisms, preventive therapy strategies using chronic infusion of adrenomedullin, vascular endothelial growth factor-121 (VEGF-121), losartan, and sildenafil have been proposed to block narrow spiral artery formation in the placenta by suppressing related possible factors for pre-eclampsia. However, although such preventive treatments have been partly successful, they have failed in ameliorating fetal growth restriction and carry the risk of possible side-effects of drugs on pregnant mothers. In this study, we attempted to develop a new symptomatic treatment for pre-eclampsia by directly rescuing placental ischemia with artificial oxygen carriers (hemoglobin vesicles: HbV) since previous data indicate that placental ischemia/hypoxia may alone be sufficient to lead to pre-eclampsia through up-regulation of sFlt-1, one of the main candidate molecules for the cause of pre-eclampsia. Using a rat model, the present study demonstrated that a simple treatment using hemoglobin vesicles for placental ischemia rescues placental and fetal hypoxia, leading to appropriate fetal growth. The present study is the first to demonstrate hemoglobin vesicles successfully decreasing maternal plasma levels of sFlt-1 and ameliorating fetal growth restriction in the pre-eclampsia rat model (p < 0.05, one-way ANOVA). In future, chronic infusion of hemoglobin vesicles could be a potential effective and noninvasive therapy for delaying or even alleviating the need for Caesarean sections in pre-eclampsia.

Targeting SOD1 induces synthetic lethal killing in BLM- and CHEK2-deficient colorectal cancer cells

Cancer is a major cause of death throughout the world, and there is a large need for better and more personalized approaches to combat the disease. Over the past decade, synthetic lethal approaches have been developed that are designed to exploit the aberrant molecular origins (i.e. defective genes) that underlie tumorigenesis. BLM and CHEK2 are two evolutionarily conserved genes that are somatically altered in a number of tumor types. Both proteins normally function in preserving genome stability through facilitating the accurate repair of DNA double strand breaks. Thus, uncovering synthetic lethal interactors of BLM and CHEK2 will identify novel candidate drug targets and lead chemical compounds. Here we identify an evolutionarily conserved synthetic lethal interaction between SOD1 and both BLM and CHEK2 in two distinct cell models. Using quantitative imaging microscopy, real-time cellular analyses, colony formation and tumor spheroid models we show that SOD1 silencing and inhibition (ATTM and LCS-1 treatments), or the induction of reactive oxygen species (2ME2 treatment) induces selective killing within BLM- and CHEK2-deficient cells relative to controls. We further show that increases in reactive oxygen species follow SOD1 silencing and inhibition that are associated with the persistence of DNA double strand breaks, and increases in apoptosis. Collectively, these data identify SOD1 as a novel candidate drug target in BLM and CHEK2 cancer contexts, and further suggest that 2ME2, ATTM and LCS-1 are lead therapeutic compounds warranting further pre-clinical study.

The LDL/HDL ratio and atherosclerosis in ankylosing spondylitis

OBJECTIVES

In ankylosing spondylitis (AS) patients, cardiac and vascular involvement may manifest as atherosclerosis and coronary artery disease. Systemic inflammation, oxidative stress, increased low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol constitute a significant risk for atherosclerosis. This study investigated the relationship between carotid intima-media thickness (CIMT), LDL/HDL ratio, total oxidant status (TOS; an indicator of oxidative stress) and ischemic modified albumin (IMA; an ischemic marker in AS patients).

PATIENTS AND METHODS

Sixty AS patients were diagnosed using the Modified New York Criteria; 54 age- and gender-matched participants were included as controls. CIMT, LDL/HDL ratio, TOS and IMA were measured using the most appropriate methods.

RESULTS

IMA was higher in AS patients compared to controls (p < 0.0001). TOS was also increased in AS patients (p = 0.005); as was CIMT (p < 0.0001). The LDL/HDL ratio was also greater in AS patients compared to controls (p = 0.047). A positive correlation was found between CIMT and LDL/HDL ratio among AS patients.

CONCLUSION

Elevated CIMT, IMA and TOS levels suggest an increased risk of atherosclerotic heart disease in AS patients. The LDL/HDL ratio was higher in AS patients compared to controls, and there was a correlation between LDL/HDL ratio and CIMT, albeit statistically weak. Therefore, the LDL/HDL ratio is not a reliable marker to predict atherosclerotic heart disease in AS patients.

Interaction Between ALK1 Signaling and Connexin40 in the Development of Arteriovenous Malformations

OBJECTIVE

To determine the role of Gja5 that encodes for the gap junction protein connexin40 in the generation of arteriovenous malformations in the hereditary hemorrhagic telangiectasia type 2 (HHT2) mouse model.

APPROACH AND RESULTS

We identified GJA5 as a target gene of the bone morphogenetic protein-9/activin receptor-like kinase 1 signaling pathway in human aortic endothelial cells and importantly found that connexin40 levels were particularly low in a small group of patients with HHT2. We next took advantage of the Acvrl1(+/-) mutant mice that develop lesions similar to those in patients with HHT2 and generated Acvrl1(+/-); Gja5(EGFP/+) mice. Gja5 haploinsufficiency led to vasodilation of the arteries and rarefaction of the capillary bed in Acvrl1(+/-) mice. At the molecular level, we found that reduced Gja5 in Acvrl1(+/-) mice stimulated the production of reactive oxygen species, an important mediator of vessel remodeling. To normalize the altered hemodynamic forces in Acvrl1(+/-); Gja5(EGFP/+) mice, capillaries formed transient arteriovenous shunts that could develop into large malformations when exposed to environmental insults.

CONCLUSIONS

We identified GJA5 as a potential modifier gene for HHT2. Our findings demonstrate that Acvrl1 haploinsufficiency combined with the effects of modifier genes that regulate vessel caliber is responsible for the heterogeneity and severity of the disease. The mouse models of HHT have led to the proposal that 3 events-heterozygosity, loss of heterozygosity, and angiogenic stimulation-are necessary for arteriovenous malformation formation. Here, we present a novel 3-step model in which pathological vessel caliber and consequent altered blood flow are necessary events for arteriovenous malformation development.