VEGF-induced blood flow increase causes vascular hyper-permeability in vivo

Therapeutic effectiveness of upadacitinib on individual types of rash in Japanese patients with moderate-to-severe atopic dermatitis

Atopic dermatitis (AD) is a chronic eczematous disease with various types of rash, erythema, edema/papulation, excoriation, or lichenification. Janus kinase 1 inhibitor upadacitinib is effective for moderate-to-severe AD. We aimed to investigate the therapeutic effects of upadacitinib on each rash type in AD patients in real-world clinical practice. Seventy-two Japanese patients with moderate-to-severe AD were treated with oral upadacitinib 15 mg/day plus topical corticosteroids. The Eczema Area and Severity Index (EASI) scores for erythema, edema/papulation, excoriation, or lichenification on the whole body or on head and neck, upper limbs, lower limbs, or trunk were assessed at weeks 0, 4, and 12 of treatment. The proportions of patients who achieved resolution or at least 75% reduction of EASI from baseline (EASI 75) for individual rash types were calculated at weeks 4 and 12 on the whole body or each anatomical site. The resolution rates for excoriation, erythema, edema/papulation, or lichenification on the whole body were 38.3%, 23.7%, 21.7%, and 8.3% at week 4 and 18.3%, 18.6%, 11.6%, and 13.3% at week 12, respectively. The EASI scores for all rash types significantly decreased at weeks 4 and 12 compared to week 0. The achievement rates of EASI 75 for excoriation, erythema, edema/papulation, or lichenification on the whole body were 67.2%, 66.7%, 49.2%, and 37.7% at week 4 and 57.3%, 65%, 41%, and 41% at week 12, respectively. The achievement rate of EASI 75 for erythema on head and neck at week 4 (45.3%) was lower than that on upper limbs (71%) and on lower limbs (70.8%), and that on head and neck at week 12 (42.2%) was lower than that on lower limbs (69.2%). These results indicate that upadacitinib is effective for all AD rash types, especially for excoriation and erythema, while head-and-neck erythema might be less responsive to upadacitinib.

Effectiveness of switching from baricitinib 4 mg to upadacitinib 30 mg in patients with moderate-to-severe atopic dermatitis: a real-world clinical practice in Japan

BACKGROUND

Atopic dermatitis (AD) is a chronic eczematous disease with severe pruritus. Janus kinase (JAK) inhibitors, upadacitinib, baricitinib, and abrocitinib, are systemic treatments for AD. The outcomes of switching from one JAK inhibitor to another have not been examined.

OBJECTIVES

We assessed the outcomes of switching from baricitinib 4 mg to upadacitinib 30 mg in Japanese patients with moderate-to-severe AD.

METHODS

Twenty patients treated with baricitinib 4 mg, showing insufficient response or adverse events, were switched to treatment with upadacitinib 30 mg. We evaluated total eczema area and severity index (EASI), EASI at head and neck, trunk, upper, or lower limbs, EASI of erythema, edema/papulation, excoriation, or lichenification, and peak pruritus numerical-rating scale (PP-NRS) at baseline (start of baricitinib), weeks 0 (time of switching), and 4 and 12 after switching.

RESULTS

Total EASI, EASI at each anatomical site, EASI of each clinical sign, and PP-NRS were markedly reduced at weeks 4 or 12 compared to week 0. Achievement rates of more than 75% or 90% reduction of EASI from baseline significantly improved after switching.

CONCLUSIONS

Switching from baricitinib 4 mg to upadacitinib 30 mg effectively improved rash and pruritus.

Effectiveness and Safety of Upadacitinib in Combination with Topical Corticosteroids in Adolescent Patients with Moderate-to-Severe Atopic Dermatitis

Purpose

To investigate the therapeutic effectiveness and safety of Janus kinase 1 inhibitor upadacitinib in adolescent patients with atopic dermatitis (AD).

Patients and Methods

This study examined therapeutic effectiveness and safety of upadacitinib for 39 Japanese adolescent patients (aged 12-17 years) diagnosed with moderate-to-severe AD from August 2021 to January 2023. The patients were treated with upadacitinib 15 mg/day plus twice daily topical corticosteroids. Total eczema area and severity index (EASI) or EASI on head and neck, upper limbs, lower limbs, and trunk or for erythema, edema/papulation, excoriation, or lichenification, atopic dermatitis control tool (ADCT), peak pruritus-numerical rating scale (PP-NRS), and laboratory indexes were assessed at weeks 0, 4, and 12 of treatment. Treatment-emergent adverse events were recorded.

Results

Total EASI or EASI on 4 anatomical sites or for 4 rash types, ADCT, and PP-NRS were significantly reduced at week 4 and 12 compared to week 0. The achievement rates at weeks 4 or 12 were 64.1% or 62.5% for EASI 75, 93.5% or 73.1% for ADCT <7-point, and 80.6% or 60% for PP-NRS ≥4-point improvement, respectively, indicating their peak at week 4 and slight decrease at week 12. The percent reduction of EASI for excoriation was higher than that for lichenification or edema/papulation at week 4 or week 12, respectively. The percent reductions of EASI for erythema and edema/papulation on head and neck were lower than those on lower limbs at week 12. Total eosinophil counts (TEC) and IgE reduced at week 4 compared to week 0 while TARC, IgE, TEC, and LDH increased at week 12 compared to week 4.

Conclusion

These results suggest therapeutic effectiveness and tolerability of upadacitinib and support its therapeutic usefulness for adolescent AD patients.

HIF-1, an important regulator in potential new therapeutic approaches to ischemic stroke

Ischemic stroke is a leading cause of disability and mortality worldwide due to the narrow therapeutic window of the only approved therapies like intravenous thrombolysis and thrombectomy. Hypoxia inducible factor-1α (HIF-1α) is a sensitive regulator of oxygen homeostasis, and its expression is rapidly induced after hypoxia/ischemia. It plays an extensive role in the pathophysiology of stroke by regulating multiple pathways including glucose metabolism, angiogenesis, neuronal survival, neuroinflammation and blood brain barrier regulation. Here, we give a brief overview of the HIF-1α-targeting strategies currently under investigation and summarise recent research on how HIF-1α is regulated in various brain cells, including neurons and microglia, at various stages in ischemic stroke. The roles of HIF-1 in stroke varies with ischemic time and degree of ischemia, are still up for debate. More focus has been placed on prospective HIF-1α targeting drugs, such as HIF-1α activator, HIF-1α stabilizers, and natural compounds. In this review, we have highlighted the regulation of HIF-1α in the novel therapeutic approaches for treatment of stroke.

Effects of Aerobic vs. Resistance Exercise on Vascular Function and Vascular Endothelial Growth Factor in Older Women

This study aimed to investigate the effects of different types of exercise (aerobic vs. resistance) on vascular function and vascular endothelial growth factor in older women. Forty-three older women, aged 65-75 years old, voluntarily participated in this study. All participants were randomly assigned to one of the following three groups: aerobic exercise (AE; n = 14), resistance exercise (RE; n = 15), and control (CG; n = 14) groups. All participants in the exercise groups performed their respective exercises for 60 min/day, three days/week, for 16 weeks. The intensity of aerobic and resistance exercises was determined using the individual heart rate reserve (40-60%) and RPE (12-13), respectively. The vascular function test included the brachial-ankle pulse wave velocity (ba-PWV), carotid artery blood flow volume, and velocity. Participants' blood samples were collected to analyze the vascular endothelial growth factor (VEGF). A significance level of 0.05 was set. Our results showed that ba-PWV improved following both AE (14.5%) and RE groups (11.1%) (all p < 0.05). Increases in carotid blood flow volume (AE: 15.4%, RE: 18.6%) and total artery peak velocity (AE: 20.4%, RE: 17%) were observed in AE and RE groups (p < 0.05), while flow total artery mean velocity (36.2%) and peak velocities (20.5%) were only increased in the aerobic exercise group (p < 0.05). VEGF was increased after resistance exercise (p < 0.05). Overall, aerobic exercise provides greater benefits on vascular function than resistance exercise but further research is needed on VEGF regarding whether this change is associated with vascular function improvement in older women.

Peptide Lv augments intermediate-conductance calcium-dependent potassium channels (KCa3.1) in endothelial cells to promote angiogenesis

Peptide Lv is a small endogenous secretory peptide that is expressed in various tissues and conserved across different species. Patients with diabetic retinopathy, an ocular disease with pathological angiogenesis, have upregulated peptide Lv in their retinas. The pro-angiogenic activity of peptide Lv is in part through promoting vascular endothelial cell (EC) proliferation, migration, and sprouting, but its molecular mechanism is not completely understood. This study aimed to decipher how peptide Lv promotes EC-dependent angiogenesis by using patch-clamp electrophysiological recordings, Western immunoblotting, quantitative PCR, and cell proliferation assays in cultured ECs. Endothelial cells treated with peptide Lv became significantly hyperpolarized, an essential step for EC activation. Treatment with peptide Lv augmented the expression and current densities of the intermediate-conductance calcium-dependent potassium (KCa3.1) channels that contribute to EC hyperpolarization but did not augment other potassium channels. Blocking KCa3.1 attenuated peptide Lv-elicited EC proliferation. These results indicate that peptide Lv-stimulated increases of functional KCa3.1 in ECs contributes to EC activation and EC-dependent angiogenesis.

Association of neovascular age-related macular degeneration with migraine

Patients with early onset vascular pathology have been reported to manifest neovascular age-related macular degeneration (AMD). While the blood vessels involved in pathogenesis of migraine remains controversial, it is generally accepted that a major contributor is blood vessel pathology. This study aimed to examine the association between migraine and AMD using a nationwide population-based dataset. Retrospective claims data were collected from the Taiwan National Health Insurance Research Database. We identified 20,333 patients diagnosed with neovascular AMD (cases), and we selected 81,332 propensity score-matched controls from the remaining beneficiaries in Taiwan's National Health Insurance system. We used Chi-square tests to explore differences in the prevalence of migraine prior to the index date between cases and controls. We performed multiple logistic regressions to estimate the odds of prior migraine among neovascular AMD patients vs. controls after adjusting for age, sex, monthly income, geographic location, residential urbanization level, hyperlipidemia, diabetes, coronary heart disease, hypertension, and previous cataract surgery. A total of 5184 of sample patients (5.1%) had a migraine claim before the index date; 1215 (6.1%) among cases and 3969 (4.9%) among controls (p < 0.001), with an unadjusted OR of 1.239 (95% CI 1.160~1.324, p < 0.001) for prior migraine among cases relative to controls. Furthermore, the adjusted OR was 1.201 (95% CI 1.123~1.284; p < 0.001) for AMD cases relative to controls. The study offers population-based evidence that persons with migraine have 20% higher risk of subsequently being diagnosed with neovascular AMD.

Biological Functions and Regulatory Mechanisms of Hypoxia-Inducible Factor-1α in Ischemic Stroke

Ischemic stroke is caused by insufficient cerebrovascular blood and oxygen supply. It is a major contributor to death or disability worldwide and has become a heavy societal and clinical burden. To date, effective treatments for ischemic stroke are limited, and innovative therapeutic methods are urgently needed. Hypoxia inducible factor-1α (HIF-1α) is a sensitive regulator of oxygen homeostasis, and its expression is rapidly induced after hypoxia/ischemia. It plays an extensive role in the pathophysiology of stroke, including neuronal survival, neuroinflammation, angiogenesis, glucose metabolism, and blood brain barrier regulation. In addition, the spatiotemporal expression profile of HIF-1α in the brain shifts with the progression of ischemic stroke; this has led to contradictory findings regarding its function in previous studies. Therefore, unveiling the Janus face of HIF-1α and its target genes in different type of cells and exploring the role of HIF-1α in inflammatory responses after ischemia is of great importance for revealing the pathogenesis and identifying new therapeutic targets for ischemic stroke. Herein, we provide a succinct overview of the current approaches targeting HIF-1α and summarize novel findings concerning HIF-1α regulation in different types of cells within neurovascular units, including neurons, endothelial cells, astrocytes, and microglia, during the different stages of ischemic stroke. The current representative translational approaches focused on neuroprotection by targeting HIF-1α are also discussed.

VE-cadherin-based matrix promoting the self-reconstruction of pro-vascularization microenvironments and endothelial differentiation of human mesenchymal stem cells

Regulating the secretion and endothelial differentiation of human mesenchymal stem cells (hMSCs) plays an important role in the vascularization in tissue engineering and regenerative medicine. In this study, a recombinant cadherin fusion protein consisting of a human vascular endothelial-cadherin extracellular domain and immunoglobulin IgG Fc region (hVE-cad-Fc) was developed as a bioartificial matrix for modulating hMSCs. The hVE-cad-Fc matrix significantly enhanced the secretion of angiogenic factors, activated the VE-cadherin-VEGFR2/FAK-AKT/PI3K signaling pathway in hMSCs, and promoted the endothelial differentiation of hMSCs even without extra VEGF. Furthermore, the hVE-cad-Fc matrix was applied for the surface modification of a poly (lactic-co-glycolic acid) (PLGA) porous scaffold, which significantly improved the hemocompatibility and vascularization of the PLGA scaffold in vivo. These results revealed that the hVE-cad-Fc matrix should be a superior bioartificial ECM for remodeling the pro-vascularization extracellular microenvironment by regulating the secretion of hMSCs, and showed great potential for the vascularization in tissue engineering.

Effects of Axial Compression and Distraction on Vascular Bud and VEGFA Expression in the Vertebral Endplate of an Ex Vivo Rabbit Spinal Motion Segment Culture Model

STUDY DESIGN

An ex vivo study of the rabbit's vertebral endplate.

OBJECTIVE

The aim of this study was to assess the effect of axial compression and distraction on vascular buds and vascular endothelial growth factor (VEGFA) expression of the vertebral endplate (VEP).

SUMMARY OF BACKGROUND DATA

The abnormal load can lead to intervertebral disc degeneration (IDD), whereas axial distraction can delay this process. The effects of different mechanical loads on the intervertebral disc (IVD) have been hypothesized to be related to changes in the vascular buds of the VEP; moreover, the process that might involve the vascular endothelial growth factor (VEGF) within the VEP.

METHODS

Rabbit spinal segments (n = 40) were harvested and randomly classified into four groups: Control group, no stress was applied; Group A, a constant compressive load applied; Group B, compression load removed for a fixed time daily on a continuous basis, and substituted with a distraction load for 30 minutes; and Group C, compression removed for 30 minutes for a fixed period daily on a continuous basis. Tissue specimens were collected before the culture (day 0) and on day 14 post-culture of each group for analysis of IVDs' morphology, and protein and mRNA expression of Aggrecan, COL2al, VEGFA, and vascular endothelial growth factor receptor 2 of the VEPs.

RESULTS

Application of axial distraction and dynamic load compression significantly delayed time- and constant compression-mediated VEP changes and IDD. Moreover, the degree of degeneration was associated with loss of vascular buds, as well as the downregulation of VEGFA and its receptor.

CONCLUSION

The regulation of vascular buds and VEGF expression in the VEP represents one of the mechanisms of axial distraction and dynamic loading.Level of Evidence: N/A.

Neuroprotective Factors of the Retina and Their Role in Promoting Survival of Retinal Ganglion Cells: A Review

Retinal ganglion cells (RGCs) play a crucial role in the visual pathway. As their axons form the optic nerve, apoptosis of these cells causes neurodegenerative vision loss. RGC death could be triggered by increased intraocular pressure, advanced glycation end products, or mitochondrial dysfunction. In this review, we summarize the role of some neuroprotective factors in RGC injury: ciliary neurotrophic factor (CNTF), nerve growth factor (NGF), brain-derived neurotrophic factor, vascular endothelial growth factor, pigment epithelium-derived factor, glial cell line-derived neurotrophic factor, and Norrin. Each, in their own unique way, prevents RGC damage caused by glaucoma, ocular hypertension, ischemic neuropathy, and even oxygen-induced retinopathy. These factors are produced mainly by neurons, leukocytes, glial cells, and epithelial cells. Neuroprotective factors act via various signaling pathways, including JAK/STAT, MAPK, TrkA, and TrkB, which promotes RGC survival. Many attempts have been made to develop therapeutic strategies using these factors. There are ongoing clinical trials with CNTF and NGF, but they have not yet been accepted for clinical use.

Constant compression decreases vascular bud and VEGFA expression in a rabbit vertebral endplate ex vivo culture model

SUMMARY OF BACKGROUND DATA

The vascular buds in the vertebral endplate (VEP) are the structural foundation of nutrient exchange in the intervertebral disc (IVD). VEGF is closely related to angiogenesis in the endplate and intervertebral disc degeneration (IDD).

OBJECTIVE

To investigate the effects of static load on vascular buds and VEGF expression in the VEP and to further clarify the relation between IDD and VEGF.

METHODS

IVD motion segments were harvested from rabbit lumbar spines and cultured under no-loading conditions (controls) or in custom-made apparatuses under a constant compressive load (0.5 MPa) for up to 14 days. Tissue integrity and the number of vascular buds were determined, and the concentrations and expression of Aggrecan, COL2a1, and VEGFA in the VEPs were assessed after 3, 7, and 14 days of culturing and then compared with those of fresh tissues.

RESULTS

Under the constant compression, the morphological integrity of the VEPs was gradually disrupted, and immunohistochemistry results showed a significant decrease in the levels of Agg and COL2a1. During the static load, the number of vascular buds in the VEPs was gradually reduced from the early stage of culture, and ELISA showed that the constant compressive load caused a significant decrease in the VEGFA and VEGFR2 protein concentrations, which were consistent with the immunohistochemistry results. Western blot and RT-PCR results also showed that the loading state caused a significant decrease in VEGFA expression compared with that of fresh and control samples.

CONCLUSIONS

Constant compression caused degeneration of the VEP as well as a decreased number of vascular buds, thereby accelerating disc degeneration. VEGFA is involved in this process. We anticipate that regulating the expression of VEGFA may improve the condition of the lesions to the vascular buds in the endplates, thus enhancing the nutritional supply function in IVD and providing new therapeutic targets and strategies for the effective prevention and treatment of IDD.

Role of increased vascular permeability in chemotherapy-induced alopecia: In vivo imaging of the hair follicular microenvironment in mice

Chemotherapy-induced alopecia is one of the most difficult adverse events of cancer treatment for patients. However, it is still unknown why anticancer drugs cause hair loss. We aimed to clarify the mechanism of chemotherapy-induced alopecia in mice using an in vivo imaging technique with a two-photon microscope, which enables observation of the deep reaction in the living body in real time. In this study, ICR mice were injected intraperitoneally with cyclophosphamide (120 µg/g). Changes in the hair bulb morphology, subcutaneous vessel permeability, and vessel density were evaluated by two-photon microscopy and conventional methods. In order to determine whether there is a causal relationship between vascular permeability and hair loss, we combined cyclophosphamide (50 µg/g) with subcutaneous histamine. Using two‐photon microscopy and conventional examination, we confirmed that the hair bulbs became smaller, blood vessels around the hair follicle decreased, and vascular permeability increased at 24 hours after cyclophosphamide injection [corrected]. Apoptosis occurred in vascular endothelial cells around the hair follicle. Additionally, hair loss was exacerbated by temporarily enhancing vascular permeability with histamine. In conclusion, cyclophosphamide caused a decrease in vascular density and an increase in vascular permeability, therefore increased vascular permeability might be one of the causes of chemotherapy-induced alopecia.

Vascular Permeability Assays In Vivo

Whereas physiological vascular permeability (VP) mediates selective transport of plasma, electrolytes, proteins, and cells across an intact endothelial barrier, pathological VP results in the loss of endothelial barrier integrity. Whereas physiological VP is a feature of regular host defense and tissue repair, compromised barrier function may lead to aberrant vascular leakage, concurrent tissue edema, and inflammation eventually causing life-threatening conditions such as acute lung injury or acute respiratory distress syndrome, cancer, kidney injury, etc. Measurement of VP helps to identify, design, and optimize anti-leak therapies. Further, it can define the effect of a stimulus or a gene modulation in endothelial-barrier regulation. The degree of VP can be of importance to determine the stage of cancer and disease prognosis. This chapter discusses Miles assay, which is a well-established, relatively simple, and a reliable in vivo technique to assess VP as a surrogate measurement. Although a reliable technique, Miles assay is time-consuming, and the technique does not consider the compounding factors that may increase VP independently of endothelial-barrier regulation, such as blood pressure or blood flow. As an alternative, we describe fluorescein isothiocyanate-dextran lung permeability assay, a method that can also be adapted to measure VP and edema in other organs such as the brain and kidney.

Effects of Remote Ischemic Conditioning on Cerebral Hemodynamics in Ischemic Stroke

Ischemic stroke is one of the most common cerebrovascular diseases and is the leading cause of disability all over the world. It is well known that cerebral blood flow (CBF) is disturbed or even disrupted when ischemic stroke happens. The imbalance between demand and shortage of blood supply makes ischemic stroke take place or worsen. The search for treatments that can preserve CBF, especially during the acute phase of ischemic stroke, has become a research hotspot. Animal and clinical experiments have proven that remote ischemic conditioning (RIC) is a beneficial therapeutic strategy for the treatment of ischemic stroke. However, the mechanism by which RIC affects CBF has not been fully understood. This review aims to discuss several possible mechanisms of RIC on the cerebral hemodynamics in ischemic stroke, such as the improvement of cardiac function and collateral circulation of cerebral vessels, the protection of neurovascular units, the formation of gas molecules, the effect on the function of vascular endothelial cells and the nervous system. RIC has the potential to become a therapeutic treatment to improve CBF in ischemic stroke. Future studies are needed to highlight our understanding of RIC as well as accelerate its clinical translation.

Effects of the Humanized Anti-Adrenomedullin Antibody Adrecizumab (HAM8101) on Vascular Barrier Function and Survival in Rodent Models of Systemic Inflammation and Sepsis

PURPOSE

Adrenomedullin (ADM) is an important regulator of endothelial barrier function during sepsis. Administration of a murine antibody targeted against the N-terminus of ADM (HAM1101) resulted in improved outcome in models of murine sepsis. We studied the effects of a humanized form of this antibody (HAM8101, also known as Adrecizumab) on vascular barrier dysfunction and survival in rodent models of systemic inflammation and sepsis.

METHODS

Rats (n=48) received different dosages of HAM8101 or placebo (n = 8 per group), directly followed by administration of lipopolysaccharide (5 mg/kg). Twenty-four hours later, Evans Blue dye was administered to assess vascular leakage in kidney and liver tissue. Furthermore, mice (n = 24) were administered different dosages of HAM8101 or placebo (n = 6 per group), immediately followed by cecal ligation and puncture (CLP). Eighteen hours later, albumin, vascular endothelial growth factor (VEGF), and angiopoietin-1 were analyzed in the kidney. Finally, effects of single and repeated dose administration of HAM1101, HAM8101 and placebo on survival were assessed in CLP-induced murine sepsis (n = 60, n = 10 per group).

RESULTS

Dosages of 0.1 and 2.5 mg/kg HAM8101 attenuated renal albumin leakage in endotoxemic rats. Dosages of 0.1, 2.0, and 20 mg/kg HAM8101 reduced renal concentrations of albumin and the detrimental protein VEGF in septic mice, whereas concentrations of the protective protein angiopoietin-1 were augmented. Both single and repeated administration of both HAM1101 and HAM8101 resulted in improved survival during murine sepsis.

CONCLUSIONS

Pretreatment with the humanized anti-ADM antibody HAM8101 improved vascular barrier function and survival in rodent models of systemic inflammation and sepsis.

Vascular Effects of Adrenomedullin and the Anti-Adrenomedullin Antibody Adrecizumab in Sepsis

Sepsis remains a major scientific and medical challenge, for which, apart from significant refinements in supportive therapy, treatment has barely changed over the last few decades. During sepsis, both vascular tone and vascular integrity are compromised, and contribute to the development of shock. The free circulating peptide adrenomedullin (ADM) is involved in the regulation of the endothelial barrier function and tone of blood vessels. Several animal studies have shown that ADM administration improves outcome of sepsis. However, in higher dosages, ADM administration may cause hypotension, limiting its clinical applicability. Moreover, ADM has a very short half-life and easily adheres to surfaces, further hampering its clinical use. The non-neutralizing anti-ADM antibody Adrecizumab (HAM8101) which causes a long-lasting increase of plasma ADM has shown promising results in animal models of systemic inflammation and sepsis; it reduced inflammation, attenuated vascular leakage, and improved hemodynamics, kidney function, and survival. Combined with an excellent safety profile derived from animal and phase I human studies, Adrecizumab represents a promising candidate drug for the adjunctive treatment of sepsis. In this review, we first provide a brief overview of the currently available data on the role of adrenomedullin in sepsis and describe its effects on endothelial barrier function and vasodilation. Furthermore, we provide a novel hypothesis concerning the mechanisms of action through which Adrecizumab may exert its beneficial effects in sepsis.

Novel Heparin Receptor Transmembrane Protein 184a Regulates Angiogenesis in the Adult Zebrafish Caudal Fin

Transmembrane protein 184A (TMEM184A) was recently identified as the heparin receptor in vascular cells. Heparin binds specifically to TMEM184A and induces anti-proliferative signaling in vitro. Though it is highly conserved, the physiological function of TMEM184A remains unknown. The objective of this study was to investigate the expression and effects on vascular regeneration of TMEM184A using the adult zebrafish regenerating caudal fin as an in vivo model. Here, we show that Tmem184a is expressed in vascular endothelial cells (ECs) of mature and regenerating zebrafish fins. Transient morpholino (MO)-mediated knockdown of Tmem184a using two validated MOs results in tangled regenerating vessels that do not grow outward and limit normal overall fin regeneration. A significant increase in EC proliferation is observed. Consistent with in vitro work with tissue culture vascular cells, heparin has the opposite effect and decreases EC proliferation which also hinders overall fin regeneration. Collectively, our study suggests that Tmem184a is a novel regulator of angiogenesis.

Effects of kallidinogenase on retinal edema and size of non-perfused areas in mice with retinal vein occlusion

Kallidinogenase has been used to treat retinal vein occlusion (RVO) in patients, although there are no evidences on the effects of kallidinogenase on the retinal edema and the non-perfused areas in eyes with a RVO. We have established a murine RVO model with retinal edema and non-perfused areas. The purpose of this study was to evaluate the effects of kallidinogenase on the retinal edema and size of the non-perfused areas in the mouse RVO model. We evaluated the thickness of the retinal layers and size of the non-perfused areas, and the blood flow by laser speckle flowgraphy in RVO model. The effects of an intravenous injection of kallidinogenase on the retinal edema and size of the non-perfused areas were determined. In addition, the expressions of phosphorylated protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) were measured by Western blotting. Our results showed that kallidinogenase reduced the degree of retinal edema and size of the non-perfused areas by an increase in the blood flow in RVO model. Kallidinogenase also increased the levels of phosphorylated Akt and eNOS. These findings indicate that kallidinogenase acted through Akt/eNOS-dependent phosphorylation. Thus, kallidinogenase should be considered as a possible therapeutic agent for RVO patients.

Effects of PI and PIII Snake Venom Haemorrhagic Metalloproteinases on the Microvasculature: A Confocal Microscopy Study on the Mouse Cremaster Muscle

The precise mechanisms by which Snake Venom Metalloproteinases (SVMPs) disrupt the microvasculature and cause haemorrhage have not been completely elucidated, and novel in vivo models are needed. In the present study, we compared the effects induced by BaP1, a PI SVMP isolated from Bothrops asper venom, and CsH1, a PIII SVMP from Crotalus simus venom, on cremaster muscle microvasculature by topical application of the toxins on isolated tissue (i.e., ex vivo model), and by intra-scrotal administration of the toxins (i.e., in vivo model). The whole tissue was fixed and immunostained to visualize the three components of blood vessels by confocal microscopy. In the ex vivo model, BaP1 was able to degrade type IV collagen and laminin from the BM of microvessels. Moreover, both SVMPs degraded type IV collagen from the BM in capillaries to a higher extent than in PCV and arterioles. CsH1 had a stronger effect on type IV collagen than BaP1. In the in vivo model, the effect of BaP1 on type IV collagen was widespread to the BM of arterioles and PCV. On the other hand, BaP1 was able to disrupt the endothelial barrier in PCV and to increase vascular permeability. Moreover, this toxin increased the size of gaps between pericytes in PCV and created new gaps between smooth muscle cells in arterioles in ex vivo conditions. These effects were not observed in the case of CsH1. In conclusion, our findings demonstrate that both SVMPs degrade type IV collagen from the BM in capillaries in vivo. Moreover, while the action of CsH1 is more directed to the BM of microvessels, the effects of BaP1 are widespread to other microvascular components. This study provides new insights in the mechanism of haemorrhage and other pathological effects induced by these toxins.

A new algorithm for a better characterization and timing of the anti-VEGF vascular effect named "normalization"

Antiangiogenics are widely used in cancer treatment in combination with chemotherapy and radiotherapy for their vascular effects. Antiangiogenics are supposed to induce morphological and functional changes in the chaotic tumor vasculature that would help enhance the therapeutic efficacy of chemotherapy and radiotherapy through the amelioration of the drug delivery or the oxygenation in the tumor, respectively. However, finding the best treatment sequence is not an easy task to achieve and no consensus has yet been established because of the lack of knowledge regarding when and for how long the vascular network is ameliorated. The aim of this work was to develop a dedicated image processing algorithm able to analyze the vascular structures on optical microscopy images of the vascular network and to follow its fine modifications in vivo, over time. We applied this algorithm to follow the evolution of the vascular parameters (vascularized tissue surface, branches, sprouts and length), in response or not to anti-VEGF therapy (10 mg/kg/day) and determine precisely whether there is really a vascular "normalization" with anti-VEGF therapy in comparison with the parameters extracted from healthy vascular networks. We found that for this determination, the choice of region of interest to analyze is critical as it is important to compare only microcirculation areas and avoid areas with arteriole-venule-capillary hierarchy. The algorithm analysis allowed us to define a vascular "normalization" in treated tumors, between 8 and 12 days of bevacizumab treatment that was confirmed by standard immunohistochemical analysis, microvascular permeability assessment and immunohistological blood perfusion assessment.

Vascular endothelium - Gatekeeper of vessel health

The vascular endothelium is an interface between the blood stream and the vessel wall. Changes in this single cell layer of the artery wall are believed of primary importance in the pathogenesis of vascular disease/atherosclerosis. The endothelium responds to humoral, neural and especially hemodynamic stimuli and regulates platelet function, inflammatory responses, vascular smooth muscle cell growth and migration, in addition to modulating vascular tone by synthesizing and releasing vasoactive substances. Compromised endothelial function contributes to the pathogenesis of cardiovascular disease; endothelial 'dysfunction' is associated with risk factors, correlates with disease progression, and predicts cardiovascular events. Therapies for atherosclerosis have been developed, therefore, that are directed towards improving endothelial function.

Sevoflurane prevents lipopolysaccharide-induced barrier dysfunction in human lung microvascular endothelial cells: Rho-mediated alterations of VE-cadherin

Acute lung injury (ALI) mainly occurs as increased permeability of lung tissue and pleural effusion. Inhaled anesthetic sevoflurane has been demonstrated to alleviate lung permeability by upregulating junction proteins after ischemia-reperfusion. However, the exact mechanisms of its protective effect on reperfusion injury remain elusive. The aim of this study was to assess possible preconditioning with sevoflurane in an in vitro model of lipopolysaccharide (LPS)-induced barrier dysfunction in human lung microvascular endothelial cells (HMVEC-Ls). In this study, HMVEC-Ls were exposed to minimum alveolar concentration of sevoflurane for 2 h. LPS significantly increased the permeability of HMVEC-L. Moreover, the distribution of junction protein, vascular endothelial (VE)-cadherin, in cell-cell junction area and the total expression in HMVEC-Ls were significantly decreased by LPS treatment. However, the abnormal distribution and decreased expression of VE-cadherin and hyperpermeability of HMVEC-Ls were significantly reversed by pretreatment with sevoflurane. Furthermore, LPS-induced activation of the RhoA/ROCK signaling pathway was significantly inhibited with sevoflurane. Such activation, abnormal distribution and decreased expression of VE-cadherin and hyperpermeability of HMVEC-Ls were significantly inhibited with sevoflurane pretreatment or knockdown of RhoA or ROCK-2. In conclusion, sevoflurane prevented LPS-induced rupture of HMVEC-L monolayers by suppressing the RhoA/ROCK-mediated VE-cadherin signaling pathway. Our results may explain, at least in part, some beneficial effects of sevoflurane on pulmonary dysfunction such as ischemia-reperfusion injury.