Postcapillary Venules Research Articles

Crohn's disease and ulcerative colitis share two molecular subtypes with different mechanisms and drug response.

Several therapies have been approved to treat crohn's disease (CD) and ulcerative colitis (UC), indicating that both diseases may share the same molecular subtypes. The aim of this study is to identify shared patient subtypes with common molecular drivers of disease. Five public datasets with 406 CD and 421 UC samples were integrated to identify molecular subtypes. Then, the patient labels from six independent datasets and eight treatment datasets were predicted for validating subtypes and identifying the relationship with response status of corticosteroids, infliximab, vedolizumab, and ustekimumab. Two molecular subtypes were identified from the training datasets, in which CD and UC patients were relatively evenly represented in each subtype. We found six S1-specific gene modules related to innate/adaptive immune responses and tissue remodeling and nine S1-specific cell types (cycling T, Tregs, cd8+ lamina propria, follicular B, cycling B plasma, inflammatory monocytes, inflammatory fibroblast, and post-capillary venules). Subtype S2 was associated with three modules related to metabolism functions and four cell types (immature enterocytes, transit amplifying, immature goblet and WNT5B+). The subtypes can be replicated in six independent datasets based on a 20-gene classifier. Furthermore, response rates to four treatments in subtype S2 were significantly higher than those in subtype S1. This study discovered and validated a robust transcriptome-based molecular classification shared by CD and UC and built a 20-gene classifier. Because two subtypes have different molecular mechanisms and drug response, our classification may aid interpretation of heterogeneous molecular and clinical information in IBD patients.

Proresolving Lipid Mediators in the Respiratory System.

Lung inflammation, infection, and injury can lead to critical illness and death. The current means to pharmacologically treat excessive uncontrolled lung inflammation needs improvement because many treatments are or will become immunosuppressive. The inflammatory response evolved to protect the host from microbes, injury, and environmental insults. This response brings phagocytes from the bloodstream to the tissue site to phagocytize and neutralize bacterial invaders and enables airway antimicrobial functions. This physiologic response is ideally self-limited with initiation and resolution phases. Polyunsaturated essential fatty acids are precursors to potent molecules that govern both phases. In the initiation phase, arachidonic acid is converted to prostaglandins and leukotrienes that activate leukocytes to transmigrate from postcapillary venules. The omega-3 fatty acids (e.g., DHA and EPA) are precursors to resolvins, protectins, and maresins, which are families of chemically distinct mediators with potent functions in resolution of acute and chronic inflammation in the respiratory system.

Diagnostics and treatment of urticarial vasculitis associated with COVID-19

Currently, the problem of COVID-19 continues. The possible consequences of acute infection are not entirely clear. Various dermatological manifestations of COVID-19, including urticarial vasculitis (UV), are increasingly being reported. Urticarial vasculitis (UV) is a rare chronic inflammatory disease presenting with long-lasting wheals with or without angioedema [1]. Histopathological, UV is a leukocytoclastic vasculitis, a common form of small vessel vasculitis, including arterioles, capillaries, and postcapillary venules, in which the inflammatory infiltrate consists of neutrophils with fibrinoid necrosis and nuclear disintegration into fragments (“leukocytoclasia”) [1]. We report a case of urticular vasculitis in a 54-year-old woman who does not suffer from systemic diseases, with a burdened allergic anamnesis (drug allergy to levomycetin with a clinic of widespread toxicoderma). For 2 months after discharge, the patient took colchicine at a dosage of 0.5 mg, 1 tablet 2 times a day, which reduced the manifestation of clinical symptoms and achieved remission. According to the results of a comprehensive examination, a previously transferred COVID-19 infection is considered as a likely etiological factor.

Retinal perivascular macrophages regulate immune cell infiltration during neuroinflammation in mouse models of ocular disease.

The blood-retina barrier (BRB), which is disrupted in diabetic retinopathy (DR) and uveitis, is an important anatomical characteristic of the retina, regulating nutrient, waste, water, protein, and immune cell flux. The BRB is composed of endothelial cell tight junctions, pericytes, astrocyte end feet, a collagen basement membrane, and perivascular macrophages. Despite the importance of the BRB, retinal perivascular macrophage function remains unknown. We found that retinal perivascular macrophages resided on postcapillary venules in the superficial vascular plexus and expressed MHC class II. Using single-cell RNA-Seq, we found that perivascular macrophages expressed a prochemotactic transcriptome and identified platelet factor 4 (Pf4, also known as CXCL4) as a perivascular macrophage marker. We used Pf4Cre mice to specifically deplete perivascular macrophages. To model retinal inflammation, we performed intraocular CCL2 injections. Ly6C+ monocytes crossed the BRB proximal to perivascular macrophages. Depletion of perivascular macrophages severely hampered Ly6C+ monocyte infiltration. These data suggest that retinal perivascular macrophages orchestrate immune cell migration across the BRB, with implications for inflammatory ocular diseases including DR and uveitis.

Heterogeneous Patterns of Endothelial NF-κB p65 and MAPK c-Jun Activation, Adhesion Molecule Expression, and Leukocyte Recruitment in Lung Microvasculature of Mice with Sepsis.

Sepsis is an uncontrolled systemic inflammatory response to an infection that can result in acute failure of the function of the lung called acute respiratory distress syndrome. Leukocyte recruitment is an important hallmark of acute lung failure in patients with sepsis. Endothelial cells (EC) participate in this process by facilitating tethering, rolling, adhesion, and transmigration of leukocytes via adhesion molecules on their cell surface. In in vivo studies, endothelial nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 and mitogen-activated protein kinase (MAPK) c-Jun intracellular signal transduction pathways were reported to regulate the expression of adhesion molecules. Mice underwent cecal ligation and puncture (CLP) to induce polymicrobial sepsis and were sacrificed at different time points up to 72 h after sepsis onset. Immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were used to determine the kinetics of nuclear localization of p65 and c-Jun in EC, expression and location of adhesion molecules E-selectin and vascular cell adhesion molecule 1 (VCAM-1). Furthermore, the extent and location of leukocyte recruitment were assessed based on Ly6G staining of neutrophils, cluster determinant (CD) 3 staining of T lymphocytes, and CD68 staining of macrophages. In all pulmonary microvascular beds, we identified p65 and c-Jun nuclear accumulation in a subset of endothelial cells within the first 24 h after CLP-sepsis initiation. E-selectin protein was expressed in a subset of microvessels at 4 and 7 h after sepsis initiation, while VCAM-1 was expressed in a scattered pattern in alveolar tissue and microvessels, without discernible changes during sepsis development. CLP-induced sepsis predominantly promoted the accumulation of neutrophils and T lymphocytes 4 and 7 h after disease onset. Neutrophil accumulation occurred in all pulmonary microvascular beds, while T lymphocytes were present in alveolar tissue and postcapillary venules. Taken together, nuclear localization of p65 and c-Jun in EC and neutrophil recruitment could be associated with induced E-selectin expression in the pulmonary microvessels in CLP-septic mice at the early stage of the disease. In alveolar capillaries, on the other hand, activation of these molecular pathways and leukocyte accumulation occurred in the absence of E-selectin or VCAM-1. Endothelial activation and leukocyte recruitment in sepsis-induced lung injury are regulated by multiple, heterogeneously controlled mechanisms, which vary depending on the type of microvascular bed involved.

Conditions that promote transcellular neutrophil migration in vivo

Circulating leukocytes enter tissue either through endothelial junctions (paracellular) or via a pore through the body of endothelial cells (transcellular). We have previously shown that genetically replacing VE-cadherin with a VE-cadherin-α-catenin (VEC-αC) fusion construct—which binds constitutively to actin—obstructs junctions, and blocks leukocyte extravasation in lung, skin and postcapillary venules of cremaster muscle. However, neutrophil recruitment into the inflamed peritoneal cavity was unimpaired. Investigating reasons for this, here, we visualized neutrophil diapedesis by 3D intravital video microscopy in the cremaster muscle and omentum, the major site of neutrophil recruitment into the peritoneal cavity. We found that 80% of neutrophil-extravasation occurred through HEVs in the omentum, which was unimpaired by VEC-αC. In addition, in larger venules (60–85 µm) of both tissues, less than 15% of neutrophils extravasated transcellularly in WT mice. However, in VEC-α-C mice, transcellular diapedesis increased severalfold in the omentum, but not in the cremaster. In line with this, omental venules expressed higher levels of ICAM-1 and atypical chemokine receptor 1. Furthermore, only in the omentum, VEC-αC expression caused reduced elongation of venular endothelium in flow-direction, suggesting different biomechanical properties. Collectively, VEC-αC does not inhibit paracellular transmigration in all types of venules and can modulate the diapedesis route.

The role of galectins in mediating the adhesion of circulating cells to vascular endothelium.

Vascular cell adhesion is a complex orchestration of events that commonly feature lectin-ligand interactions between circulating cells, such as immune, stem, and tumor cells, and endothelial cells (ECs) lining post-capillary venules. Characteristically, circulating cell adherence to the vasculature endothelium is initiated through interactions between surface sialo-fucosylated glycoprotein ligands and lectins, specifically platelet (P)- or endothelial (E)-selectin on ECs or between leukocyte (L)-selectin on circulating leukocytes and L-selectin ligands on ECs, culminating in circulating cell extravasation. This lectin-ligand interplay enables the migration of immune cells into specific tissue sites to help maintain effective immunosurveillance and inflammation control, the homing of stem cells to bone marrow or tissues in need of repair, and, unfortunately, in some cases, the dissemination of circulating tumor cells (CTCs) to distant metastatic sites. Interestingly, there is a growing body of evidence showing that the family of β-galactoside-binding lectins, known as galectins, can also play pivotal roles in the adhesion of circulating cells to the vascular endothelium. In this review, we present contemporary knowledge on the significant roles of host- and/or tumor-derived galectin (Gal)-3, -8, and -9 in facilitating the adhesion of circulating cells to the vascular endothelium either directly by acting as bridging molecules or indirectly by triggering signaling pathways to express adhesion molecules on ECs. We also explore strategies for interfering with galectin-mediated adhesion to attenuate inflammation or hinder the metastatic seeding of CTCs, which are often rich in galectins and/or their glycan ligands.

The immune response to systemically administered endotoxin in the murine intestinal microcirculation under pentobarbital versus isoflurane anesthesia.

Pentobarbital and isoflurane are commonly used veterinary anesthetics. Due to the dangers of overdose by repeat-bolus regimen of pentobarbital, isoflurane has been recommended. However, literature suggests isoflurane-induced inhibition of cytokine and adhesion molecule release, impacting leukocyte adhesion. This study aims to characterize the impacts of pentobarbital versus isoflurane on leukocyte interactions within the intestinal microcirculation with and without endotoxin challenge. Female BALB/c mice were subjected to pentobarbital or isoflurane (N = 20) and challenged with endotoxin or saline by intraperitoneal injection. The mice were kept under anesthesia for 2 hours. Fluorochromes, rhodamine-6 G and fluorescein isothiocyanate, were injected intravenously. To visualize leukocyte adhesion within the intestinal microcirculation, laparotomy and intravital microscopy was performed. Leukocyte rolling and adhesion was quantified offline in a blinded fashion. Within collecting venules, leukocyte rolling and adhesion showed no significant differences between pentobarbital and isoflurane anesthesia under basal conditions. Endotoxin challenge caused a similar response in both anesthetic groups. Within postcapillary venules, no statistical differences between the two anesthetics were found for adhering leukocytes under basal conditions or following endotoxin challenge either. However, leukocyte rolling after LPS-challenge was significantly decreased in postcapillary venules during isoflurane anesthesia compared to pentobarbital anesthesia. Isoflurane anesthesia showed only minor differences in the immune response to endotoxin within the intestinal microcirculation compared to pentobarbital anesthesia. Due to the superior safety profile of volatile anesthetics, immunological studies may choose isoflurane over pentobarbital as the veterinary anesthetic of choice.

The clinical and pathological features of Kimura disease in pediatric patients.

Kimura disease is characterized by inflammation, with its underlying causes remaining uncertain. There is a lack of comprehensive and systematic research on the pathology of this condition in pediatric patients. Our objective is to study the clinical and pathological attributes of Kimura disease in pediatric patients and investigate the potential diagnostic significance of immunoglobulin E (IgE) in this context. Clinical and laboratory information, pathological characteristics, and follow-up data were correlated to examine the distinctive features. Immunohistochemistry, acid-fast staining, and molecular assay were used to identify the presence of IgE and pathogens. We conducted an analysis of five cases of Kimura disease in pediatric patients at our hospital. The patients' ages ranged from 5 years and 7 months to 14 years and 2 months, with 4 (80%) being male. The most common site was the head and neck region, particularly the postauricular subcutaneous area. Eosinophilia was observed in four patients (80%), and two patients (40%) had elevated serum immunoglobulin E (IgE) levels. Histopathological changes included eosinophilic infiltrates, follicular hyperplasia, and the proliferation of postcapillary venules. Immunohistochemical results supported the reactive nature of the lymphoid process and IgE deposition in the follicle, while no specific pathogens were discovered by special staining. All patients underwent surgical excision, and none experienced recurrence in their original location. Children with Kimura disease show distinct eosinophilic and IgE alterations in both laboratory findings and pathological features. The application of immunohistochemical staining of IgE could serve as a promising marker for diagnosing Kimura disease.

Clinical and morphological features of Osler-Weber-Randu disease with signs of visceral injury

Randu-Osler-Weber disease or hereditary hemorrhagic telangiectasia is an autosomal dominant disorder characterized by dilated capillaries and veins, which are usually localized on the skin and mucous membranes of the oral cavity, as well as in the respiratory, urinary and digestive tracts. The anatomical basis of the disease is damage to blood vessels with degeneration and hypoplasia of the muscle and elastic layers, resulting in focal thinning of the vessel walls with further expansion of their lumen. Violation of angiogenesis persists throughout the patient's life, and is manifested by the formation of aneurysms, telangiectasias, and arteriovenous shunts. The average life expectancy of patients with burdened heredity is 63.2 years. The peak of mortality occurs at the age of 50, which is mainly associated with acute complications of the disease. However, among people suffering from Randu-Osler-Weber disease there are also long-lived people who die at the age of 70-79 years, and the cause of death is the complication of the main disease and the addition of chronic diseases. The purpose of this article is to consider in more detail possible manifestations and complications, methods of treatment of Randu-Osler-Weber disease for timely recognition of the disease and provision of timely medical assistance. This article describes a case of an abdominal form of hereditary hemorrhagic telangiectasia in an 82-year-old patient. The results of the postmortem pathomorphological examination of damaged tissues due to Randu-Osler-Weber disease are presented. During the study of micropreparations of the mucous lip, small intestine, mesentery of the small intestine and liver, groups of vessels were found, the wall of which is thinned in places and thickened in places, in the wall of these vessels there is a decrease or complete absence of muscle and elastic fibers, only endothelium is present, surrounded by loose connective tissue, postcapillary venules expand and anastomose with arterioles. In the lumen of these falsely developed vessels, mixed thrombi are determined. An elderly patient suffered from a combined pathology: hereditary hemorrhagic telangiectasia with arterio-venous malformations in the liver, heart, mesentery, small intestine, and coronary heart disease. These processes were complicated by the development of congestive heart failure, which disturbed the hemodynamic and rheological properties of blood and contributed to the occurrence of thrombosis of arterio-venous malformations in the mesentery and the wall of the small intestine. In the following, necrosis of the loops of the small intestine occurred with the development of diffuse purulent-fibrinous peritonitis and endogenous intoxication. Patients with hereditary hemorrhagic telangiectasia have a higher risk of bleeding and neurological complications, including anemia, cerebral abscess, stroke, venous thrombosis, and heart failure, because of late diagnosis of this hereditary disease. Early diagnosis is based on clinical data and careful collection of family history. In 90% of patients under the age of 40, the diagnosis of hereditary hemorrhagic telangiectasia can be established using the Curaçao criteria. This disease brings a significant amount of suffering in everyday life for both patients and their families, and requires significant attention of a multidisciplinary team of doctors at every stage of medical care.

QUANTITATIVE MORPHOLOGICAL ANALYSIS OF THE FEATURES OF REMODELING OF HEMOMICROCIRCULATORY VESSELS IN THE TESTIS OF EXPERIMENTAL ANIMALS AT CONDITIONS OF ETHANOL INTOXICATION

Ethanol is classifi ed as a vascular poison, long-term intoxication of which negatively aff ects almost all organs and systems body of humans and experimental animals. Morphological changes in testes during ethanol poisoning have not been studied enough. The aim of the study was a quantitative morphological analysis of the features of the remodeling of blood vessels of the hemomicrocirculatory bed of the left and right testes at conditions of ethanol intoxication. The structures of the left and right testis of 30 white male rats, which were divided into 2 groups, were morphologically and morphometrically studied. The 1 group included 15 intact animals, the 2-15 rats, which were injected intragastrically with a 30 % ethanol solution at the rate of 2 ml per 100 g of body weight for 28 days once a day. A month after the start of the experiment, the experimental animals were euthanized by bloodletting under thiopental anesthesia. Histological and semithin sections were made from testes. The outer and inner diameters, wall thickness of arterioles, precapillary arterioles, hemocapillaries, postcapillary venules and venules were determined. Quantitative indicators were processed statistically.It was established that twenty- eight days of ethanol intoxication in laboratory sexually mature white male rats leads to pronounced remodeling of the blood vessels of the hemomicrocirculatory bed of the left and right testes, which is characterized by narrowing of the lumens and thickening of the walls of its arterial (arterioles, precapillary arterioles) and exchange (hemocapillaries) vessels. pronounced expansion and thinning of the walls of postcapillary venules and venules, venous hemoptysis, hypoxia, dystrophic- necrotic changes in cells, stromal structures, infi ltration and sclerosis. The revealed remodeling of blood vessels of the hemomicrocirculatory bed in conditions of ethanol poisoning dominates in the left testicle.

Is chronic urticaria or urticarial vasculitis a diagnostic dilemma?

Introduction. Urticarial vasculitis (UV) is a rare disease that has two components: clinical manifestations of urticaria and histopathological signs of cutaneous leukocytoclastic vasculitis of small vessels, predominantly involving postcapillary venules. This condition is characterized by chronic or recurrent episodes of urticaria, each element of which lasts more than 24 hours and is accompanied by a feeling of pain and burning. The aim is to reveal the key points of pathogenetic mechanisms, differential diagnosis and therapeutic tactics of UV based on a clinical case. Clinical case. A clinical case of a 17-year-old boy with normocomplementemic UV is described. The patient's main complaint was a long-lasting rash (more than three weeks) with itching. From the anamnesis it is known that the provoking factors for the onset of the disease were an insect bite and the start of taking a new drug, namely vitamin K (two days before the onset of the disease). Throughout this time, the child was examined by various specialists and received treatment. Alternative diagnoses: bacterial folliculitis, viral exanthem, unspecified urticaria. There was no positive effect from the received treatment. The diagnosis of UV was made in the sixth week of the disease using a punch biopsy. Regression of the skin syndrome was achieved using a combination of antihistamine and antileukotriene drugs. Conclusions. Performing a punch biopsy, which is currently the gold standard for diagnosis, allows us to solve the diagnostic dilemma: “UV or chronic urticaria”. Timely diagnosis helps to avoid false diagnoses and, as a result, incorrect treatment of UV. The description of this clinical case is a contribution to the disclosure of this globally complex problem. The research was carried out in accordance with the principles of the Declaration of Helsinki. The informed consent of the child and child's parents was obtained for conducting the research. No conflict of interest was declared by the authors.

The rheology of interactions between leukocytes, platelets and the vessel wall in thrombo-inflammation.

Leukocytes and platelets must adhere to the wall of blood vessels to carry out their protective functions in inflammation and haemostasis. Recruitment is critically dependent on rheological variables (wall shear rate and stress, red cell aggregation and haematocrit) which affect delivery to the vessel wall as well as velocities and forces experienced there. Leukocyte recruitment is efficient only up to wall shear rates of about 300s-1 and usually restricted to low-shear post-capillary venules in inflammation. Being smaller, platelets experience lower velocities and shear forces adjacent to the wall and can adhere at much higher shear rates for haemostasis in arteries. In addition, we found quite different effects of variations in haematocrit or red cell aggregation on attachment of neutrophils or platelets, which also assist their separate recruitment in venules or arteries. However, it has become increasingly evident that inflammatory and thrombotic responses may occur together, with platelets promoting the adhesion and activation of neutrophils and monocytes. Indeed, it is 30 years since we demonstrated that platelets could cause neutrophils to aggregate in suspension and, when attached to a surface, could support selectin-mediated rolling of all leukocytes. Thrombin-activated platelets could further induce neutrophil activation and immobilisation. In some conditions, platelets could bind to intact endothelial monolayers and capture neutrophils or monocytes. Subsequently, we found that extracellular vesicles released by activated platelets (PEV) fulfilled similar functions when deposited on surfaces or bound to endothelial cells. In murine models, platelets or PEV could act as bridges for monocytes in inflamed vessels. Thus, leukocytes and platelets are rheologically adapted for their separate functions, while novel thrombo-inflammatory pathways using platelets or PEV may underlie pathogenic leukocyte recruitment.

Sepsis induces heterogeneous transcription of coagulation- and inflammation-associated genes in renal microvasculature

BackgroundAcute kidney injury (AKI) in sepsis patients increases patient mortality. Endothelial cells are important players in the pathophysiology of sepsis-associated AKI (SA-AKI), yet knowledge regarding their spatiotemporal involvement in coagulation disbalance and leukocyte recruitment is lacking. This study investigated the identity and kinetics of responses of different microvascular compartments in kidney cortex in response to SA-AKI. MethodsLaser microdissected arterioles, glomeruli, peritubular capillaries, and postcapillary venules from kidneys of mice subjected to cecal ligation and puncture (CLP) were analyzed using RNA sequencing. Differential expression and pathway enrichment analyses identified genes involved in coagulation and inflammation. A selection of these genes was evaluated by RT-qPCR in microvascular compartments of renal biopsies from patients with SA-AKI. The role of two identified genes in lipopolysaccharide-induced endothelial coagulation and inflammatory activation were determined in vitro in HUVEC using siRNA-based gene silencing. ResultsCLP-sepsis in mice induced altered expression of approximately 400 genes in the renal microvasculature, with microvascular compartments exhibiting unique spatiotemporal responses. In mice, changes in gene expression related to coagulation and inflammation were most extensive in glomeruli at early and intermediate time points, with high induction of Plat, Serpine1, Thbd, Icam1, Stat3, and Ifitm3. In human SA-AKI, PROCR and STAT3 were induced in postcapillary venules, while SERPINE1 expression was diminished. IFITM3 was increased in arterioles and glomeruli. In vitro studies revealed that STAT3 and IFITM3 partly control endothelial coagulation and inflammatory activation. ConclusionRenal microvascular compartments in mice and humans exhibited heterogeneous changes in coagulation- and inflammation-related gene expression in response to SA-AKI. Additional research should aim at understanding the functional consequences of the here described heterogeneous microvascular responses to establish the usefulness of identified genes as therapeutic targets in SA-AKI.

Repositioning the Early Pathology of Type 1 Diabetes to the Extraislet Vasculature.

Type 1 diabetes (T1D) is a prototypic T cell-mediated autoimmune disease. Because the islets of Langerhans are insulated from blood vessels by a double basement membrane and lack detectable lymphatic drainage, interactions between endocrine and circulating T cells are not permitted. Thus, we hypothesized that initiation and progression of anti-islet immunity required islet neolymphangiogenesis to allow T cell access to the islet. Combining microscopy and single cell approaches, the timing of this phenomenon in mice was situated between 5 and 8 wk of age when activated anti-insulin CD4 T cells became detectable in peripheral blood while peri-islet pathology developed. This "peri-insulitis," dominated by CD4 T cells, respected the islet basement membrane and was limited on the outside by lymphatic endothelial cells that gave it the attributes of a tertiary lymphoid structure. As in most tissues, lymphangiogenesis seemed to be secondary to local segmental endothelial inflammation at the collecting postcapillary venule. In addition to classic markers of inflammation such as CD29, V-CAM, and NOS, MHC class II molecules were expressed by nonhematopoietic cells in the same location both in mouse and human islets. This CD45- MHC class II+ cell population was capable of spontaneously presenting islet Ags to CD4 T cells. Altogether, these observations favor an alternative model for the initiation of T1D, outside of the islet, in which a vascular-associated cell appears to be an important MHC class II-expressing and -presenting cell.

A Closer Look at the Perivascular Unit in the Development of Enlarged Perivascular Spaces in Obesity, Metabolic Syndrome, and Type 2 Diabetes Mellitus.

The recently described perivascular unit (PVU) resides immediately adjacent to the true capillary neurovascular unit (NVU) in the postcapillary venule and contains the normal-benign perivascular spaces (PVS) and pathological enlarged perivascular spaces (EPVS). The PVS are important in that they have recently been identified to be the construct and the conduit responsible for the delivery of metabolic waste from the interstitial fluid to the ventricular cerebrospinal fluid for disposal into the systemic circulation, termed the glymphatic system. Importantly, the outermost boundary of the PVS is lined by protoplasmic perivascular astrocyte endfeet (pvACef) that communicate with regional neurons. As compared to the well-recognized and described neurovascular unit (NVU) and NVU coupling, the PVU is less well understood and remains an emerging concept. The primary focus of this narrative review is to compare the similarities and differences between these two units and discuss each of their structural and functional relationships and how they relate not only to brain homeostasis but also how they may relate to the development of multiple clinical neurological disease states and specifically how they may relate to obesity, metabolic syndrome, and type 2 diabetes mellitus. Additionally, the concept and importance of a perisynaptic astrocyte coupling to the neuronal synapses with pre- and postsynaptic neurons will also be considered as a perisynaptic unit to provide for the creation of the information transfer in the brain via synaptic transmission and brain homeostasis. Multiple electron microscopic images and illustrations will be utilized in order to help explain these complex units.

Raynaud’s Phenomenon as a Manifestation of Vasculitis C – ANCA: Case Report and Literature Review

Raynaud's phenomenon is a vasospastic condition affecting capillaries in the distal region of the extremities. It is divided into primary and secondary and 80-90% of patients are associated with primary or idiopathic disease, while 10-20% are secondary, with multiple etiologies including connective tissue, vascular, hematologic, and endocrinopathic diseases. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) correspond to a group of necrotizing vasculitides of medium (0.2 to 2.0 mm in diameter) and small blood vessels (arterioles, capillaries, postcapillary venules). Clinically, it is characterized by multisystem involvement, with upper and lower respiratory tract and renal damage standing out for their frequency. The least frequent manifestations are cutaneous, with digital ischemia and gangrene occurring in less than 1% of cases. The diagnosis is based on a detailed clinical history and physical examination in addition to complementary studies including a complete metabolic panel, muscle enzymes, viral panel, thyroid profile and a rheumatologic panel to assess secondary causes of Raynaud's phenomenon. Calcium antagonists are considered the first-line treatment in both etiologies, and phosphodiesterase-5 inhibitors are another alternative. This article presents a case of a patient with Raynaud's phenomenon as an initial clinical manifestation and later presentation of C-ANCA vasculitis.

Peptidomics insights: neutrophil extracellular traps (NETs) related to the chronic subdural hemorrhage.

Chronic subdural hemorrhage (CSDH) refers to a hematoma with an envelope between the dura mater and the arachnoid membrane and is more common among the elderly. It was reported that the dura mater, which is highly vascularized with capillary beds, precapillary arterioles and postcapillary venules play an important role in the protection of the central nervous system (CNS). Numerous evidences suggests that peptides play an important role in neuroprotection of CNS. However, whether dura mater derived endogenous peptides participate in the pathogenesis of CSDH remains undetermined. In the current study, the peptidomic profiles were performed in human dura of CSDH (three patients) and the relative control group (three non-CSDH samples) by LC-MS (liquid chromatography-mass spectrometry). The results suggested that a total of 569 peptides were differentially expressed in the dura matter of CSDH compared with relative controls, including 217 up-regulated peptides and 352 down-regulated peptides. Gene Ontology (GO) analysis demonstrated that the precursor proteins of those differentially expressed peptides were involved in the various biological processes. Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that NETs participated in the pathogenies of CSDH. Further investigate showed that H3Cit was significantly elevated in the dural and hematoma membranes of patients with CSDH compared to patients without CSDH. Taken together, our results showed the differentially expressed peptides in human dura mater of CSDH and demonstrated that NETs formation in the dural and hematoma membranes might be involved in the pathogenesis of CSDH. It is worth noting that pharmacological inhibition of NETs may have potential therapeutic implications for CSDH.

Protoplasmic Perivascular Astrocytes Play a Crucial Role in the Development of Enlarged Perivascular Spaces in Obesity, Metabolic Syndrome, and Type 2 Diabetes Mellitus

Astrocytes (ACs) are the most abundant cells in the brain and, importantly, are the master connecting and communicating cells that provide structural and functional support for brain cells at all levels of organization. Further, they are recognized as the guardians and housekeepers of the brain. Protoplasmic perivascular astrocyte endfeet and their basal lamina form the delimiting outermost barrier (glia limitans) of the perivascular spaces in postcapillary venules and are important for the clearance of metabolic waste. They comprise the glymphatic system, which is critically dependent on proper waste removal by the pvACef polarized aquaporin-4 water channels. Also, the protoplasmic perisynaptic astrocyte endfeet (psACef) are important in cradling the neuronal synapses that serve to maintain homeostasis and serve a functional and supportive role in synaptic transmission. Enlarged perivascular spaces (EPVS) are emerging as important aberrant findings on magnetic resonance imaging (MRI), and are associated with white matter hyperintensities, lacunes, and aging, and are accepted as biomarkers for cerebral small vessel disease, increased obesity, metabolic syndrome, and type 2 diabetes. Knowledge is exponentially expanding regarding EPVS along with the glymphatic system, since EPVS are closely associated with impaired glymphatic function and waste removal from the brain to the cerebrospinal fluid and systemic circulation. This review intends to focus on how the pvACef play a crucial role in the development of EPVS.

Characterization of Patient-Derived GNAQ Mutated Endothelial Cells from Capillary Malformations

Capillary malformations (CM) (port-wine stains) are congenital skin lesions that are characterized by dilated capillaries and postcapillary venules. CMs are caused by altered functioning of the vascular endothelium. Somatic genetic mutations have predominantly been identified in the endothelial cells of CMs, providing an opportunity for the development of targeted therapies. However, there is currently limited in-depth mechanistic insight into the pathophysiology and a lack of preclinical research approaches. In a monocenter exploratory study of 17 adult patients with CMs, we found somatic sequence variants in the GNAQ (p.R183Q, p.R183G, or p.Q209R) or GNA11 (p.R183C) genes. We applied an endothelial-selective cell isolation protocol to culture primary endothelial cells from skin biopsies from these patients. We successfully expanded patient-derived cells in culture in 3 of the 17 cases while maintaining endothelial specificity as demonstrated by vascular endothelial-cadherin immunostainings. In addition, we tested the angiogenic capacity of endothelial cells from a patient with a GNAQ (p.R183G) sequence substitution. These proof-of-principle results reveal that primary cells isolated from CMs may represent a functional research model to investigate the role of endothelial somatic mutations in the etiology of CMs, but improved isolation and culture methodologies are urgently needed to advance the field.