Vascular Hyperpermeability Research Articles

Case series: pachychoroid pigment epitheliopathy transformed to polypoidal choroidal vasculopathy after long-term follow-up

BackgroundPachychoroid pigment epitheliopathy (PPE), a retinal disorder that falls into the pachychoroid spectrum, is characterized by retinal pigment epithelium changes in pachychoroid eyes without existing or previous subretinal fluid or soft drusen. Previous reports have indicated that PPE may share some pathophysiologic component with other pachychoroid spectrum diseases and could transform into central serous chorioretinopathy (CSC) during follow-up. CSC transformation to PNV and PCV has also been reported, but PPE transformation to PCV has not been reported. Case presentationSeven eyes of seven patients (four male three female, aged 62.7 ± 8.4 years) who presented with PPE at baseline transformed to PCV during follow-up. All study eyes had baseline contralateral eye diagnoses of PCV. All PPE eyes reported no symptoms at baseline and were followed up regularly for the treatment of their contralateral eyes. All PPE presented as pigment epithelium detachment (PED) at baseline. The mean central macular thickness (CMT) was 217.6 ± 14.6 µm, the mean subfoveal choroidal thickness (SFCT) was 354.9 ± 94.9 µm, and the mean sub-PPE choroidal thickness was 332.3 ± 84.6 µm. The mean PPE width and height were 1326.4 ± 791.4 µm and 58.7 ± 23.6 µm, respectively, at baseline. Disruption of the ellipsoid zone (EZ) was noted in 3 eyes, while choroidal vascular hyperpermeability (CVH) was noted in 5 eyes at baseline. The follow-up period was 75.0 ± 41.1 months, and the mean transformation time was 49.6 ± 24.8 months. All study eyes received no intervention before transformation.ConclusionsPPE could transform to PCV after a long follow-up period. Regular follow-ups for a long time should be recommended for patients with PPE.

The importance of α1AMP-activated protein kinase (α1AMPK) in hemostatic dysfunctions induced by sepsis

Sepsis is a pathological circumstance whose outcome is associated with organ dysfunction and death. Vascular hyperpermeability and hemostasis impairment both play a key role in the onset of organ failure. Our previous work highlighted the protective role of α1AMPK against sepsis-induced hyperpermeability. However, the impact of α1AMPK on hemostasis has never been investigated in this condition. This study aims to characterize the interaction of α1AMPK with hemostasis in sepsis. α1AMPK wild type (WT) and knockout (KO) mice were challenged with intraperitoneal injection of lipopolysaccharide (LPS) from Escherichia coli O55B5 (10 mg/kg) during 6 and 18 hours. Plasmatic markers of coagulation, NETosis and platelet activation were measured by ELISA. To identify cell type responsible for the dysregulation, same analyses were conducted on endothelial-, leucocyte- or platelet- specific α1AMPK knockout mouse models. Hemostasis was altered at 6 hours and 18 hours after LPS administration, in both α1AMPK WT and KO mice. Thrombin generation, reflected by thrombin-antithrombin complex formation, was significantly increased in α1AMPK KO mice compared to WT mice, after 18 hours of treatment with LPS. In contrast, fibrinolysis was more inhibited in α1AMPK KO than in WT mice, with a higher level of plasminogen activator inhibitor-1 measured at 6 and 18 hours, while tissue plasminogen activator was not different. This exacerbated procoagulant phenotype in α1AMPK KO mice was associated with an increase of sCD62P in plasma, reflecting an overactivation of platelets under septic conditions. Septic α1AMPK KO mice also showed an increase of Neutrophil Elastase and plasma DNA with no variation of MPO-DNA complexes, suggesting that NETosis was not altered but that exacerbated cellular damages occurred in these mice compared to WT animals. Platelet- and leucocyte- specific α1AMPK knockout mouse models did not recapitulate the phenotype observed in total α1AMPK knockout mice after LPS administration. However, endothelial specific α1AMPK knockout mice showed an increase of thrombin generation with a tendency to higher platelet activation. Altogether, these results demonstrate that α1AMPK plays a crucial role in the regulation of hemostasis disturbances during sepsis. While α1AMPK from platelets and leucocytes does not contribute to the septic damage, endothelialα1AMPK might be a brake for hemostatic dysregulation.

The importance of alpha-1 AMP-activated protein kinase (α1AMPK) in hemostatic dysfunctions induced by sepsis

Sepsis is a pathological circumstance whose outcome is associated with organ dysfunction and death. Vascular hyperpermeability and hemostasis impairment, both play a key role in the onset of organ failure. Our previous work highlighted the protective role of α1AMPK against sepsis-induced hyperpermeability. However, the impact of α1AMPK on hemostasis has never been investigated in this condition. This study aims to characterize the interaction of α1AMPK with hemostasis in sepsis. α1AMPK wild type (WT) and knockout (KO) mice were challenged with intraperitoneal injection of lipopolysaccharide (LPS) from Escherichia coli O55B5 (10 mg.kg) during 6 and 18 hours. Plasmatic markers of coagulation, NETosis and platelet activation were measured by ELISA. In order to identify the origin of the dysregulation, same analyses were conducted on endothelial, leucocyte or platelet specific deletion model. In both α1AMPK WT and KO mice, hemostasis was altered at 6 hours and 18 hours after LPS administration. Thrombin generation, reflected by thrombin-antithrombin complex formation, was significantly increased in α1AMPK KO mice compared with WT mice, after 18 hours of treatment by LPS. In contrast, fibrinolysis was more inhibited in α1AMPK KO than in WT mice, with a higher level of plasminogen activator inhibitor-1 measured at 6 and 18 hours, while tissue plasminogen activator was not different. This exacerbated procoagulant phenotype in α1AMPK KO mice was associated with an increase in sCD62P in plasma, showing an overactivation of platelets under septic conditions. Septic α1AMPK KO mice showed an increase of Neutrophil Elastase and plasmatic DNA with no variation of MPO-DNA complex suggesting a stronger cellular damage than WT mice with no increase of NETosis. Platelet and leucocyte specific models did not have the phenotype observed in the total deletion model after LPS administration. However, endothelial specific model showed an increase of thrombin generation with a tendency of more platelet activation. Altogether, these results demonstrate that α1AMPK plays an important role in the regulation of hemostasis disturbances during sepsis. Specific model showed that α1AMPK from platelet and leucocyte does not contribute directly to the septic damage but endothelial α1AMPK seems to be important to contain hemostasis dysregulation.

The Endothelium and COVID-19: An Increasingly Clear Link Brief Title: Endotheliopathy in COVID-19.

The endothelium has a fundamental role in the cardiovascular complications of coronavirus disease 2019 (COVID-19). Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particularly affects endothelial cells. The virus binds to the angiotensin-converting enzyme 2 (ACE-2) receptor (present on type 2 alveolar cells, bronchial epithelial cells, and endothelial cells), and induces a cytokine storm. The cytokines tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 have particular effects on endothelial cells—leading to endothelial dysfunction, endothelial cell death, changes in tight junctions, and vascular hyperpermeability. Under normal conditions, apoptotic endothelial cells are removed into the bloodstream. During COVID-19, however, endothelial cells are detached more rapidly, and do not regenerate as effectively as usual. The loss of the endothelium on the luminal surface abolishes all of the vascular responses mediated by the endothelium and nitric oxide production in particular, which results in greater contractility. Moreover, circulating endothelial cells infected with SARS-CoV-2 act as vectors for viral dissemination by forming clusters that migrate into the circulation and reach distant organs. The cell clusters and the endothelial dysfunction might contribute to the various thromboembolic pathologies observed in COVID-19 by inducing the formation of intravascular microthrombi, as well as by triggering disseminated intravascular coagulation. Here, we review the contributions of endotheliopathy and endothelial-cell-derived extracellular vesicles to the pathogenesis of COVID-19, and discuss therapeutic strategies that target the endothelium in patients with COVID-19.

M1 Macrophages Increase Endothelial Permeability and Enhance p38 Phosphorylation via PPAR-γ/CXCL13-CXCR5 in Sepsis

Purpose: Vascular endothelial hyperpermeability and barrier disruption are involved in the initiation and development of sepsis. M1 macrophages promote inflammation in sepsis by releasing pro-inflammatory cytokines and chemokines. This study was designed to investigate the functional relationships between M1 macrophages and human umbilical vein endothelial cells (HUVECs), as well as the underlying molecular mechanisms. Methods: HUVECs were co-cultured with THP-1-derived M1 macrophages pretreated with or without rosiglitazone (RSG), a peroxisome proliferator-activated receptor (PPAR)-γ agonist. C-X-C chemokine receptor type (CXCR)5 was knocked down by short hairpin RNA lentivirus. Cecal ligation and puncture were used to induce sepsis in a mouse model. Endothelial permeability was evaluated using transendothelial electrical resistance and fluorescein isothiocyanate (FITC)-dextran assays. Results: Chemokine ligand (CXCL)13 was upregulated in M1 macrophages than M0 macrophages, as well as in the culture medium. In HUVECs co-cultured with M1 macrophages, transendothelial electrical resistance decreased, FITC-dextran flux increased, p38 phosphorylation was strengthened, and the expression of tight junction proteins (zonula occludens protein-1, occludin, and claudin-4) decreased. CXCR5 RNA interference or RSG pretreatment partially reversed these effects. A luciferase reporter assay revealed that CXCL13 was a direct target of PPAR-γ. RSG treatment decreased serum levels of creatinine, blood urea nitrogen, CXCL13, tumor necrosis factor-α, and interleukin-6, downregulated CXCL13 in peritoneal macrophages, and enhanced the survival rate of sepsis mice. Conclusion: M1 macrophages induced endothelial hyperpermeability and promoted p38 phosphorylation in sepsis by inhibiting PPAR-γ to increase CXCL13 production. PPAR-γ/CXCL13-CXCR5 signaling could be a promising novel therapeutic target for sepsis.

Genesis of Antibiotic Resistance (AR) LXXXVIII: Turbulence Modeling(TM) of Hemodynamics in Simplified Severe Sepsis Protocol‐2 (SSSP‐2)‐NCT01663701: “Hypnotic Trance Ameliorate Turbulence to Laminar Flow (Homeostasis)”: A Neuropsychiatric Basis

An effort is made to substantiate that vascular abnormalities (fluid dynamic/mechanical properties) could be restored to homeostasis by an appropriate hypnotic trance. Clinical Background:Sepsis: Clinical data/Record(observation): decreased capillary density ref Fig 4 c., PMID: 34055944, hypovolemia, endothelial dysfunction, increased WBC accumulation, thrombi deposition, altered CCP, NFP gradient, shunting, degradation of endothelial glycocalyx, vascular hyper permeability (PMID: 23566729; PMID: 20179590; PMID: 24067428), as an indicator of sepsis progress to septic shock. Neuropsychiatry diagnostic index: HAND (HIV associate neurodegenerative disorder), PTSD, psychosis, depression, mania, ANI, MND, HIV associated dementia (HAD), possible multifocal leukoencephalopathy (CMV origin, Toxoplasmaencephalitis, diffused myelin pallor, opportunistic infections, and neurosyphilis (Jarisch Herxheimer reaction). Geometry: Part I: RBC, Platelets, WBC: p47‐56; Part II: blood velocity, and function, Table 2.1; 2,2; 2.3; p63; ISBN 9780128024089; Governing Equations: Part A: CD, https://www.grc.nasa.gov/www/k‐12/airplane/shaped.html;; Part B: Keulegan – Carpenter Number equation: □=Vm/ƒoscD; Clinical Data: Hemodynamics Hypnotic Trance:Before hypnotic induction: 120.65 mmHg / 79.84 mmHg (Derived →PP= 41 mmHg Normal;Derived →MAP=93mmHg); After hypnotic induction: 115.92 mmHg /76.16 mmHg; (Derived →PP= 40 mmHg Normal;Derived →MAP= 89 mmHG)).Heart rate before hypnotic induction: 86.16 / beats per minute (Derived →CO= 86.16/ beats per minute x 70ml/min=6029.8 ml/min); After hypnotic induction, to 78.89 beats per minute (Derived →CO=78.89/ beats per minute x 70 ml/min=5522.3ml/min). (Kurnia S, et.al., (2021). Blood Pressure Control and Heart Rate: Effectiveness Brief Hypnotic Induction Methods on Adults. 10.2991/assehr.k.210423.004). Spirometry (Homeostasis): VT: 500 ml; IRV: 3100 ml; ERV: 1200 ml; VC: 4800 ml; RV: 1200 ml; A respiratory rate of 12 breaths/ minute, the minute ventilation = 12 x 500 = 6000 ml. alveoli alveolar ventilation (volume of air/min that actually reaches the alveoli) = 12 x 350 = 4200ml. Clinical correlation:The basis for correlating the sepsis, neurological(physiological/psychiatric) and hypnotic trance is that the hypnotic trance subject recovers to homeostasis provided abreaction not encountered by the subject as much as the sepsis, neurological ‐ physiological/psychiatric patients with appropriate Dx, and Tx. Taken together, it is suggested that a decrease in capillary density observed in sepsis and en route to septic shock is a transient phenomenon implicit of a reversible loss of hemodynamic function, for patients Txwith SSSP‐ERP‐EGDT similar to that of SSSP‐2 NCT0166370. Such patient cohort could possibly be reverted to sustain homeostasis in a patient‐specific hypnotic suggestion(s), re‐alert concluding with a reassuring‐post hypnotic trans conversation (devoid of abreaction).

Cell‐free Hemoglobin‐Oxidized LDL Axis Contributes to Microvascular Endothelial Barrier Dysfunction and Poor Outcomes During Sepsis

IntroductionSepsis, a dysregulated host response to infection with high morbidity and mortality, is characterized by a systemic inflammatory response and widespread vascular hyperpermeability leading to edema, organ dysfunction, and death with no specific treatments. Disruption of the microvascular endothelial barrier is a critical pathological feature of sepsis‐induced organ dysfunction driven by circulating inflammatory mediators, oxidants, and proteolytic enzymes. Cell‐free hemoglobin (CFH) is one such factor, released from damaged red blood cells during sepsis due to their increased deformability and fragility. Though CFH is not detectable in healthy subjects, plasma CFH is elevated in patients with sepsis and independently associated with mortality. CFH contributes to endothelial dysfunction, but the signaling mechanisms are incompletely understood. CFH can oxidize circulating low‐density lipoproteins (oxLDL), which could potentiate endothelial barrier disruption. We hypothesized that elevated levels of CFH during sepsis are associated with increased oxLDL and contribute to microvascular endothelial barrier dysfunction through the oxLDL receptor, lectin‐like oxidized LDL receptor 1 (LOX‐1).MethodsCirculating levels of CFH and oxLDL were measured in sepsis patients. In human lung microvascular endothelial cells (HLMVECs), transendothelial electrical resistance (TER), a measure of barrier dysfunction, was assessed by Electric Cell‐substrate Impedance Sensing (ECIS).Results (Figure)In sepsis patients, plasma oxLDL levels correlated with CFH (r=0.686; p=0.016, n=12) and were higher in patients who died in hospital (33.24 U/L [IQR 28.08, 48.28] vs. 27.19 U/L [IQR 16.24, 38.24]; p=0.045, n=25). HLMVEC barrier dysfunction induced by CFH (p<0.0001, n=6‐7) or oxLDL (p=0.002, n=4‐6) was attenuated by blocking the LOX‐1 receptor with small molecule inhibitor BI‐0115 (Boehringer Ingelheim, 20 µM; p=0.018 vs CFH, n=5; p=0.0002 vs oxLDL, n=6).ConclusionIncreased plasma CFH and oxLDL are associated with HLMVEC barrier dysfunction and poor clinical outcomes during sepsis; one mechanism by which CFH may cause vascular hyperpermeability during sepsis is through oxidation of LDL which can drive signaling through the LOX‐1 receptor.

Endothelial PP2AC prevents endotoxemia‐induced acute lung injury by suppressing STAT3 activity

Acute lung injury (ALI) is a critical hypoxemic respiratory failure characterized by alveolar‐capillary damage, unchecked inflammation, vascular leak, and pulmonary edema secondary to endothelial barrier dysfunction. Identifying the candidate molecules targeting mechanisms for excessive production of proinflammatory cytokines and endothelial dysfunction are warranted for therapeutic intervention. Recent studies show that the signal transducers and activators of transcription 3 (STAT3) phosphorylation in critical for inflammatory cytokines production and systemic inflammation. Protein phosphatase 2A (PP2A) is a hetero‐trimeric, ubiquitously expressed Ser/Thr phosphatase. The phosphatase activity of PP2A is regulated by its catalytic C subunit (PP2AC). PP2A plays an essential role in modulating tissue inflammation by maintaining the phosphorylation/de‐phosphorylation balance of multiple proteins. So far, however, no studies have deciphered PP2AC isoform‐a function in regulating pulmonary vascular endothelial permeability and inflammatory signaling. We hypothesize that PP2AC expression in vascular endothelial cell (EC) protects the lung against sepsis‐induced lung injury. Wild‐type (WT) and endothelial specific PP2AC‐deficient mice (PP2ACCKO) were challenged with lipopolysaccharide. We found that lipopolysaccharide‐induced inflammatory response, characterized by up‐regulated level of IL‐1b, IL‐6, MPO activity and pulmonary vascular hyper‐permeability in lung tissue of PP2ACCKO mice was significantly elevated as compared to WT littermate control. Mechanistically, we showed that PP2AC deletion in mouse lung‐EC and in human lung‐EC markedly augmented Ser727‐phosphorylation‐mediated STAT3 activation and MMP9 level in response to lipopolysaccharide. Intriguingly, administration of a STAT3 inhibitor suppressed lipopolysaccharide‐induced production of MMP9 and proinflammatory cytokines IL‐1b, IL‐6, MPO activity and pulmonary vascular hyper‐permeability and thus rescued the augmented inflammatory phenotype in PP2ACCKO mice lung. In conclusion, these data showed the protective role of endothelial‐PP2AC in limiting endothelial barrier dysfunction and inflammation, and thereby it attenuates sepsis‐induced lung injury by preventing hyper‐activated STAT3 signaling.

Therapeutic efficacy of humanized monoclonal antibodies targeting dengue virus nonstructural protein 1 in the mouse model.

Dengue virus (DENV) which infects about 390 million people per year in tropical and subtropical areas manifests various disease symptoms, ranging from fever to life-threatening hemorrhage and even shock. To date, there is still no effective treatment for DENV disease, but only supportive care. DENV nonstructural protein 1 (NS1) has been shown to play a key role in disease pathogenesis. Recent studies have shown that anti-DENV NS1 antibody can provide disease protection by blocking the DENV-induced disruption of endothelial integrity. We previously demonstrated that anti-NS1 monoclonal antibody (mAb) protected mice from all four serotypes of DENV challenge. Here, we generated humanized anti-NS1 mAbs and transferred them to mice after DENV infection. The results showed that DENV-induced prolonged bleeding time and skin hemorrhage were reduced, even several days after DENV challenge. Mechanistic studies showed the ability of humanized anti-NS1 mAbs to inhibit NS1-induced vascular hyperpermeability and to elicit Fcγ-dependent complement-mediated cytolysis as well as antibody-dependent cellular cytotoxicity of cells infected with four serotypes of DENV. These results highlight humanized anti-NS1 mAb as a potential therapeutic agent in DENV infection.

Osteopontin-induced vascular hyperpermeability through tight junction disruption in diabetic retina

Diabetic retinopathy is a major cause of blindness in developed countries, and is characterized by deterioration of barrier function causing vascular hyperpermeability and retinal edema. Vascular endothelial growth factor (VEGF) is a major mediator of diabetic macular edema. Although anti-VEGF drugs are the first-line treatment for diabetic macular edema, some cases are refractory to anti-VEGF therapy. Osteopontin (OPN) is a phosphoglycoprotein with diverse functions and expressed in various cells and tissues. Elevated OPN level has been implicated in diabetic retinopathy, but whether OPN is involved in hyperpermeability remains unclear. Using streptozotocin-induced diabetic mice (STZ mice) and human retinal endothelial cells (HRECs), we tested the hypothesis that up-regulated OPN causes tight junction disruption, leading to vascular hyperpermeability. The serum and retinal OPN concentrations were elevated in STZ mice compared to controls. Intravitreal injection of anti-OPN neutralizing antibody (anti-OPN Ab) suppressed vascular hyperpermeability and prevented decreases in claudin-5 and ZO-1 gene expression levels in the retina of STZ mice. Immunohistochemical staining of retinal vessels in STZ mice revealed claudin-5 immunoreactivity with punctate distribution and attenuated ZO-1 immunoreactivity, and these changes were prevented by anti-OPN Ab. Intravitreal injection of anti-OPN Ab did not change VEGF gene expression or protein concentration in retina of STZ mice. In an in vitro study, HRECs were exposed to normal glucose or high glucose with or without OPN for 48 h, and barrier function was evaluated by transendothelial electrical resistance and Evans blue permeation. Barrier function deteriorated under high glucose condition, and was further exacerbated by the addition of OPN. Immunofluorescence localization of claudin-5 and ZO-1 demonstrated punctate appearance with discontinuous junction in HRECs exposed to high glucose and OPN. There were no changes in VEGF and VEGF receptor-2 expression levels in HRECs by exposure to OPN. Our results suggest that OPN induces tight junction disruption and vascular hyperpermeability under diabetic conditions. Targeting OPN may be an effective approach to manage diabetic retinopathy.

Superresolution imaging of microvasculature at the capillary level using nanobubble contrast agents

In this work, we describe applications of nanobubbles in superresolution imaging. Conventional ultrasound localization microscopy (ULM) techniques require sparse scatterers in the form of echogenic microbubbles (MB, ∼1–10 μm diameter). ULM enables imaging of capillaries larger than ∼50 μm in diameter but becomes too time consuming in smaller capillaries due to insufficient MB density. A viable alternative for microvascular imaging may be the use of submicron bubbles, or nanobubbles (NBs). NBs are ∼100i–500 nm in diameter and have a particle density 5 orders of magnitude higher than MBs without associated attenuation artifacts. In addition to strong nonlinear response, under some conditions NBs can produce SNR linear signals stronger than erythrocytes. This allows for formulating a superresolution imaging problem using computational approaches suitable for dense sources instead of relying on physical sparsity. With much smaller sizes compared to MBs, NBs can access the smallest capillaries at much higher concentrations (∼1011), offering enhanced detection and faster superresolution acquisition. In addition, NB nonlinear signals can be decomposed to elucidate intravascular and extravasation into tissues with vascular hyperpermeability, such as tumors. Thus, when combined with appropriate processing, NBs can provide information about vascular architecture and extravascular transport which is not achievable with MBs.

Malaysian Tualang Honey Suppresses the Angiogenic Events in Endothelial Cells Induced by Vascular Endothelial Growth Factor

Anti-VEGF therapy has been used as the anti-angiogenic agent in cancer treatment. However, the treatment often couples with severe complications. Complementary natural products that offer similar anti-angiogenic potency with less side effects are sought as alternatives. Study showed that Malaysian Tualang Honey (MTH) can inhibit inflammation-induced vascular hyperpermeability in vitro and in vivo, but the effect on the angiogenesis process remains unclear. Thus, this study aims to determine the anti-angiogenic effects of MTH. Effects of MTH ranging from 0.3% to 0.9% on VEGF-induced human umbilical vein endothelial cells (HUVEC) angiogenesis was determined by proliferation, migration and tube-formation assays. Matrix metalloproteinase-2 (MMP-2) secretion from HUVEC and VEGF production from MCF7 cancer cells in response to MTH were also quantified by using ELISA kits. Suramin, an angio-suppressive agent was used as positive control. MTH significantly suppressed HUVEC proliferation (from 155% proliferation rate to 54%); migration (~ 50% inhibition rate) and tube-formation (69% reduction) induced by VEGF. These findings were explained by the significant reduction (p < 0.05) of VEGF-induced MMP-2 secretion in HUVEC with 39% suppression exhibited by 0.9% of MTH. MTH also significantly (p < 0.05) reduced VEGF secretion (19% reduction compared to control) in MCF7 breast cancer cells. Our findings suggest that the anti-angiogenic effects of MTH mainly targets endothelial cell through inhibition cell proliferation, migration and tube formation capacity, via suppression of MMP-2 secretion by the endothelial cells. However, MTH has less prominent effect on suppressing VEGF secretion by the MCF7 cancer cells.

Pathophysiological mechanisms of ALPPS: experimental model.

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage strategy that may increase hepatic tumour resectability and reduce postoperative liver failure rate by inducing rapid hypertrophy of the future liver remnant (FLR). Pathophysiological mechanisms after the first stage of ALPPS are poorly understood. An ALPPS model was established in rabbits with liver VX2 tumour. The pathophysiological mechanisms after the first stage of ALPPS in the FLR and tumour were assessed by multiplexed positron emission tomography (PET) tracers, dynamic contrast-enhanced MRI (DCE-MRI) and histopathology. Tumour volume in the ALPPS model differed from post-stage 1 ALPPS at day 14 compared to control animals. 18F-FDG uptake of tumour increased from day 7 onwards in the ALPPS model. Valid volumetric function measured by 18F-methylcholine PET showed good values in accurately monitoring dynamics and time window for functional liver regeneration (days 3 to 7). DCE-MRI revealed changes in the vascular hyperpermeability function, with a peak on day 7 for tumour and FLR. Molecular and functional imaging are promising non-invasive methods to investigate the pathophysiological mechanisms of ALPPS with potential for clinical application.

The role of S100B/RAGE-enhanced ADAM17 activation in endothelial glycocalyx shedding after traumatic brain injury

BackgroundTraumatic brain injury (TBI) remains one of the main causes for disability and death worldwide. While the primary mechanical injury cannot be avoided, the prevention of secondary injury is the focus of TBI research. Present study aimed to elucidate the effects and mechanisms of S100B and its receptor RAGE on mediating secondary injury after TBI.MethodsThis study established TBI animal model by fluid percussion injury in rats, cell model by stretch-injured in astrocytes, and endothelial injury model with conditioned medium stimulation. Pharmacological intervention was applied to interfere the activities of S100B/RAGE/ADAM17 signaling pathway, respectively. The expressions or contents of S100B, RAGE, syndecan-1 and ADAM17 in brain and serum, as well as in cultured cells and medium, were detected by western blot. The distribution of relative molecules was observed with immunofluorescence.ResultsWe found that TBI could activate the release of S100B, mostly from astrocytes, and S100B and RAGE could mutually regulate their expression and activation. Most importantly, present study revealed an obvious increase of syndecan-1 in rat serum or in endothelial cultured medium after injury, and a significant decrease in tissue and in cultured endothelial cells, indicating TBI-induced shedding of endothelial glycocalyx. The data further proved that the activation of S100B/RAGE signaling could promote the shedding of endothelial glycocalyx by enhancing the expression, translocation and activity of ADAM17, an important sheddase, in endothelial cells. The damage of endothelial glycocalyx consequently aggravated blood brain barrier (BBB) dysfunction and systemic vascular hyper-permeability, overall resulting in secondary brain and lung injury.ConclusionsTBI triggers the activation of S100B/RAGE signal pathway. The regulation S100B/RAGE on ADAM17 expression, translocation and activation further promotes the shedding of endothelial glycocalyx, aggravates the dysfunction of BBB, and increases the vascular permeability, leading to secondary brain and lung injury. Present study may open a new corridor for the more in-depth understanding of the molecular processes responsible for cerebral and systemic vascular barrier impairment and secondary injury after TBI.

COVID-19 and Lung Mast Cells: The Kallikrein-Kinin Activation Pathway.

Mast cells (MCs) have relevant participation in inflammatory and vascular hyperpermeability events, responsible for the action of the kallikrein–kinin system (KKS), that affect patients inflicted by the severe form of COVID-19. Given a higher number of activated MCs present in COVID-19 patients and their association with vascular hyperpermeability events, we investigated the factors that lead to the activation and degranulation of these cells and their harmful effects on the alveolar septum environment provided by the action of its mediators. Therefore, the pyroptotic processes throughout caspase-1 (CASP-1) and alarmin interleukin-33 (IL-33) secretion were investigated, along with the immunoexpression of angiotensin-converting enzyme 2 (ACE2), bradykinin receptor B1 (B1R) and bradykinin receptor B2 (B2R) on post-mortem lung samples from 24 patients affected by COVID-19. The results were compared to 10 patients affected by H1N1pdm09 and 11 control patients. As a result of the inflammatory processes induced by SARS-CoV-2, the activation by immunoglobulin E (IgE) and degranulation of tryptase, as well as Toluidine Blue metachromatic (TB)-stained MCs of the interstitial and perivascular regions of the same groups were also counted. An increased immunoexpression of the tissue biomarkers CASP-1, IL-33, ACE2, B1R and B2R was observed in the alveolar septum of the COVID-19 patients, associated with a higher density of IgE+ MCs, tryptase+ MCs and TB-stained MCs, in addition to the presence of intra-alveolar edema. These findings suggest the direct correlation of MCs with vascular hyperpermeability, edema and diffuse alveolar damage (DAD) events that affect patients with a severe form of this disease. The role of KKS activation in events involving the exacerbated increase in vascular permeability and its direct link with the conditions that precede intra-alveolar edema, and the consequent DAD, is evidenced. Therapy with drugs that inhibit the activation/degranulation of MCs can prevent the worsening of the prognosis and provide a better outcome for the patient.

The protective effects of Mirtazapine against lipopolysaccharide (LPS)-induced brain vascular hyperpermeability

ABSTRACT Sepsis is mainly characterized by severe inflammation triggered by infection, and sepsis-associated encephalopathy (SAE) is defined as brain damage caused by sepsis. Disruption of the blood-brain barrier (BBB) triggered by injured brain microvascular endothelial cells (BMECs) and damaged tight junction (TJ) structure is closely associated with the pathogenesis of SAE. The present research proposed to evaluate the potential therapeutic effects of Mirtazapine, a central presynaptic α2 receptor antagonist, on LPS-induced BBB disruption. The mice were administered with normal saline and 10 mg/kg Mirtazapine for 8 consecutive days, and from day 6, the experiment group of mice received LPS for 2 days to induce SAE. We found that the increased BBB permeability, elevated concentrations of inflammatory factors in brain tissues, and downregulated zonula occludens −1 (ZO-1) were observed in LPS-stimulated mice, all of which were reversed by 10 mg/kg Mirtazapine. In the in vitro assay, bEnd.3 brain endothelial cells were treated with 1 μM LPS in the absence or presence of Mirtazapine (25, 50 μM). We found that LPS-treated cells had significantly declined transendothelial electrical resistance (TEER), increased monolayer permeability, elevated production of inflammatory factors, and downregulated ZO-1. However, 25 and 50 μM Mirtazapine ameliorated all these LPS- induced aberrations. Mirtazapine also mitigated the decreased level of NF-E2–related factor 2 (Nrf2) in LPS-challenged endothelial cells. The protective effect of Mirtazapine on endothelial permeability against LPS was significantly abolished by the knockdown of Nrf2. Collectively, we concluded that Mirtazapine exerted protective effects on LPS-induced endothelial cells hyperpermeability by upregulating Nrf2.

Comparative analysis of ChAdOx1 nCoV-19 and Ad26.COV2.S SARS-CoV-2 vector vaccines.

Vector-based SARS-CoV-2 vaccines have been associated with vaccine- induced thrombosis with thrombocytopenia syndrome (VITT/TTS), but the causative factors are still unresolved. We comprehensively analyzed the ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Johnson & Johnson) vaccines. ChAdOx1 nCoV-19 contains significant amounts of host cell protein impurities, including functionally active proteasomes, and adenoviral proteins. A much smaller amount of impurities was found in Ad26.COV2.S. Platelet factor 4 formed complexes with ChAdOx1 nCoV-19 constituents, but not with purified virions from ChAdOx1 nCoV-19 or with Ad26.COV2.S. Vascular hyperpermeability was induced by ChAdOx nCoV-19 but not by Ad26.COV2.S. These differences in impurities together with EDTAinduced capillary leakage might contribute to the higher incidence rate of VITT associated with ChAdOx1 nCoV-19 compared to Ad26.COV2.S.

Choroidal vascular alterations evaluated by ultra-widefield indocyanine green angiography in central serous chorioretinopathy.

This study aims to evaluate choroidal vascular alterations in patients with central serous chorioretinopathy (CSC) using ultra-widefield (UWF) indocyanine green angiography (ICGA). This was a retrospective case-control study conducted at a single tertiary eye center. In total, 36 eyes in patients with either unilateral (24 patients) or bilateral (six patients) treatment-naïve CSC and 30 eyes in 24 age-matched controls were evaluated. The number of quadrants with vortex vein engorgement on UWF ICGA was evaluated. Dilated choroidal vessels affecting the macula were regarded as extended vortex vein engorgement. Choroidal vascular hyperpermeability (CVH) area on late-phase ICGA was quantified using stereographic projection. The parameters were compared with clinical and optical coherence tomographic findings. Eyes with CSC had larger CVH area, thicker choroid, and more quadrants with vortex vein engorgement and extended vortex vein engorgement compared with control eyes (all P < 0.001). In patients with unilateral CSC, affected eyes had larger CVH area, thicker choroid, and more extended vortex vein engorgements compared with unaffected fellow eyes (all P < 0.001), but vortex vein engorgement did not significantly differ. CVH was significantly correlated with extended vortex vein engorgement (P < 0.001) and subfoveal choroidal thickness (P = 0.007). The increased number and binocular symmetry of engorged vortex veins suggest an anatomical predisposition for CSC. CVH area and extended vortex vein engorgement were indicators of choroidal outflow congestion. These parameters may serve as diagnostic clues or predictors of disease development in eyes with CSC.

Ultra-Widefield Indocyanine Green Angiography Reveals Patterns of Choroidal Venous Insufficiency Influencing Pachychoroid Disease.

PurposeTo compare patterns of choroidal venous drainage in eyes with pachychoroid disease to those of healthy subjects using ultra-widefield indocyanine green angiography (UWF ICGA).MethodsPatients with pachychoroid disease and healthy controls were recruited at two referral centers. UWF ICGA images were used to evaluate the proportion of the postequatorial fundus drained by major vortex vein systems in each quadrant and to study the incidence and topography of choroidal vascular hyperpermeability (CVH) and intervortex venous anastomoses. Widefield swept-source optical coherence tomography (SS-OCT) was used to evaluate choroidal thickness at the posterior pole in eyes with pachychoroid disease.ResultsFifty-two pachychoroid eyes and 26 healthy eyes were evaluated. Eyes with pachychoroid disease showed a significant within-subject variance in the proportion of the postequatorial fundus drained by each vortex vein system (range, 4.1%–48.1%; P < 0.0001) that was not seen in controls (range, 17.3%–31.7%; P = 0.11). CVH was present in all pachychoroid disease eyes and three of 26 controls. Intervortex venous anastomoses were present in 46 of 52 pachychoroid disease eyes and nine of 26 control eyes. Vortex vein systems with large drainage areas showed greater density of CVH spots. SS-OCT demonstrated asymmetric choroidal drainage in the macula of 59% of pachychoroid eyes. CVH and intervortex venous anastomoses were more prominent in areas showing maximal choroidal thickness.ConclusionsIn eyes with pachychoroid disease, imbalanced choroidal venous drainage with congestion of specific vortex vein systems may contribute to a state of choroidal venous insufficiency characterized by regional choroidal thickening, CVH and remodeling of venous drainage routes.

Herbal Formulations Ameliorates Chronic Venous Insufficiency, Venotonicity and Elastase Inhibition in the Management of Varicose Veins: A Preclinical Study

Varicose vein is one of the common vascular diseases, in which veins become widened, bulged and twisted. Development of drug to combat varicose vein is a challenging task due to complex nature of the disease and non-availability of specific animal model system. In this context, relevant experimental models were developed and polyherbal formulations HVVL-041702 a liniment intended for topical use (200 µl/ animal) and HVVT-041701 a granule intended for oral use (250 mg/kg body weight, orally) were evaluated. In vitro elastase inhibition assay was carried out using the human leukocyte elastase enzyme. Ex vivo venotonic activity was performed in isolated rat vena cava. In vivo anti-inflammatory, analgesic and anti-edemagenic activity were carried out in Wistar rats. Along with the aforementioned activities, HVVT-041701 was also evaluated for chronic venous insufficiency. Both the formulations showed elastase inhibition, venotonic, anti-inflammatory, analgesic and anti-edemagenic activities. HVVT-041701 was also effective in ameliorating chronic venous insufficiency by decreasing the venous pressure. Both the formulations showed beneficial effects in the management of varicose veins by improving the tonicity, venous insufficiency and vascular hyper permeability which are the pathologic hallmark of varicose veins.