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Cholesterol crystal embolism (CCE) implies immunothrombosis, tissue necrosis, and organ failure but no specific treatments are available. As CCE involves complement activation, we speculated that inhibitors of the C5a/C5aR axis would be sufficient to attenuate the consequences of CCE like that with systemic vasculitis. Cholesterol microcrystal injection into the kidney artery of wild-type mice initiated intra-kidney immunothrombosis within a few hours followed by a sudden drop of glomerular filtration rate and ischemic kidney necrosis after 24 hours. Genetic deficiency of either C3 or C5aR prevented immunothrombosis, glomerular filtration rate drop, and ischemic necrosis at 24 hours as did preemptive treatment with inhibitors of either C5a or C5aR. Delayed C5a blockade after crystal injection still resolved crystal clots and prevented all consequences. Thus, selective blockade of C5a or C5aR is sufficient to attenuate the consequences of established CCE and prospective inhibition in high-risk patients may be clinically feasible and safe., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Antibody-mediated rejection (ABMR) is a leading cause of graft failure. Emerging evidence suggests a significant contribution of natural killer (NK) cells to microvascular inflammation (MVI). We investigated the influence of genetically determined NK cell functionality on ABMR development and activity. The study included 86 kidney transplant recipients subjected to systematic biopsies triggered by donor-specific antibody detection. We performed killer immunoglobulin-like receptor typing to predict missing self and genotyped polymorphisms determining NK cell functionality (FCGR3A V/F158 [rs396991], KLRC2 wt/del , KLRK1 HNK/LNK [rs1049174], rs9916629-C/T). Fifty patients had ABMR with considerable MVI and elevated NK cell transcripts. Missing self was not related to MVI. Only KLRC2 wt/wt showed an association (MVI score: 2 [median; interquartile range: 0-3] vs 0 [0-1] in KLRC2 wt/del recipients; P = .001) and remained significant in a proportional odds multivariable model (odds ratio, 7.84; 95% confidence interval, 2.37-30.47; P = .001). A sum score incorporating all polymorphisms and missing self did not outperform a score including only KLRC2 and FCGR3A variants, which were predictive in univariable analysis. NK cell genetics did not affect graft functional decline and survival. In conclusion, a functional KLRC2 polymorphism emerged as an independent determinant of ABMR activity, without a considerable contribution of missing self and other NK cell gene polymorphisms., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

In-depth characterization of heart-brain communication in critically ill patients with severe acute respiratory failure is attracting significant interest in the COronaVIrus Disease 19 (COVID-19) pandemic era during intensive care unit (ICU) stay and after ICU or hospital discharge. Emerging research has provided new insights into pathogenic role of the deregulation of the heart-brain axis (HBA), a bidirectional flow of information, in leading to severe multiorgan disease syndrome (MODS) in patients with confirmed infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Noteworthy, HBA dysfunction may worsen the outcome of the COVID-19 patients. In this review, we discuss the critical role HBA plays in both promoting and limiting MODS in COVID-19. We also highlight the role of HBA as new target for novel therapeutic strategies in COVID-19 in order to open new translational frontiers of care. This is a translational perspective from the Italian Society of Cardiovascular Researches., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Early clinical evidence suggests that severe cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are frequently characterized by hyperinflammation, imbalance of renin-angiotensin-aldosterone system, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In this paper, we present an immunothrombosis model of COVID-19. We discuss the underlying pathogenesis and the interaction between multiple systems, resulting in propagation of immunothrombosis, which through investigation in the coming weeks, may lead to both an improved understanding of COVID-19 pathophysiology and identification of innovative and efficient therapeutic targets to reverse the otherwise unfavorable clinical outcome of many of these patients., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Development of donor-specific antibodies is associated with reduced allograft survival in renal transplantation. Recent clinical studies highlight the prevalence of human leukocyte antigen (HLA)-DQ antibodies amongst de novo donor-specific antibodies (DSAs), yet the specific contribution of these DSAs to rejection has not been examined. Antibody-mediated rejection primarily targets the microvasculature, so this study explored how patient HLA-DQ alloantibodies can modulate endothelial activation and so immunoregulation. HLA-DQ antibodies phosphorylated Akt and S6 kinase in microvascular endothelial cells. This activation prior to culture with alloreactive lymphocytes increased IL-6 and RANTES secretion. The antibody-mediated upregulation of IL-6 was indeed Akt-dependent. The binding of HLA-DQ antibodies to endothelial cells selectively reduced T cell alloproliferation and FoxP3 high Treg differentiation. In clinical studies, detection of HLA-DQ DSAs with other DSAs is associated with worse graft survival than either alone. Endothelial cells stimulated with HLA-DR and HLA-DQ antibodies showed a synergistic increase in pro-inflammatory cytokine secretion and a decrease in Treg expansion. HLA-DQ antibodies strongly promote pro-inflammatory responses in isolation and in combination with other HLA antibodies. Thus, our data give new insights into the pathogenicity of HLA-DQ DSAs., (Copyright © 2019 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Background: Antibody-mediated rejection (ABMR) is the leading cause of kidney graft loss worldwide. Criteria for acute humoral rejection (currently labeled active humoral rejection) established by the 2007 Banff classification are highly specific but lack sensitivity. Modifications to the Banff classification were introduced for its 2013 and 2017 versions in order to identify more cases of this entity., Purpose: We intend to demonstrate that, compared to its 2007 version, the 2017 Banff classification bears an improved capacity for graft loss prediction when histologic criteria for active ABMR are met., Patients and Methods: Single-center retrospective cohort study. A random sample of 201 kidney recipients who underwent a graft biopsy since January 2004 was analyzed. Patients were classified as ever developing histologic characteristics of acute ABMR (2007 Banff) or not and renal survival between groups was compared. The same patients were then classified as ever developing histologic characteristics of active ABMR (2017 Banff) or not and renal survival was again compared. Presence of circulating donor-specific antibodies (DSA) was not taken into consideration., Results: Patients were followed for a median 13.9 ± 7.9 years, during which grafts were biopsied on 537 occasions (2.7 ± 1.6 biopsies per graft). Baseline eGFR was 73.26 ± 17.6 ml/min and baseline creatinine 1.14 ± 0.25 mg/dl. Graft loss occurred in 38 recipients (18.9%) mainly due to ABMR (60.5%). Acute ABMR (2007 Banff) was identified in 11 recipients (5.5%) and graft survival did not differ between groups with and without active ABMR occurrence (log-rank p = 0.939). Active ABMR (2017 Banff) was found in 59 recipients (29%) and graft survival was better from the second post-transplant year onward in the group of patients without active ABMR occurrence (log-rank p = 0.001). Moderate microvascular inflammation was present in 89.6% of the 48 additional patients with active ABMR., Conclusion: The 2017 Banff classification identifies more patients who develop active ABMR and stratifies graft loss risk better than the 2007 version., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Essentials The effect of alloantibodies on the endothelial expression of thrombomodulin is unknown. Thrombomodulin was quantified in stimulated endothelial cells and measured in serum samples. Anti-human leukocyte antigen (HLA) I vs. II antibodies have different effects on thrombomodulin. Anti-HLA II antibodies may promote a prothrombotic state and contribute to microangiopathy., Summary: Rationale Thrombomodulin (TBM) is an anticoagulant and anti-inflammatory transmembrane protein expressed on endothelial cells. Donor-specific alloantibodies, particularly those against human leukocyte antigen (HLA) class II, are associated with microvascular endothelial damage in solid allografts. Objective Our aim was to characterize the effects of anti-HLA antibodies on endothelial expression of TBM, and in particular, the differential effects of anti-HLA class I compared with those of anti-HLA class II. Methods We used human glomerular microvascular endothelial cells to examine TBM expression on anti-HLA-treated cells, and we tested sera from transplant recipients for soluble TBM. Results We found that whereas membrane TBM expression increased in a dose-dependent manner in the presence of anti-HLA class I antibodies, treatment with anti-HLA class II led to minimal TBM expression on the endothelial surface but to a cytosolic accumulation. Platelet adhesion studies confirmed the functional impact of anti-HLA class II. Quantitative densitometry of the membrane lysates further suggested that anti-HLA class II impairs TBM glycosylation. Furthermore, we found a significant association between the presence of circulating anti-HLA class II antibodies in transplant recipients and low serum levels of TBM. Conclusion These results indicate that ligation of anti-HLA class I and II antibodies produces different effects on the endothelial expression of TBM and on serum levels of TBM in transplant recipients. Anti-HLA class II antibodies may be associated with a prothrombotic state, which could explain the higher occurrence of microangiopathic lesions in the allograft and the poor outcomes observed in patients with these alloantibodies., (© 2017 International Society on Thrombosis and Haemostasis.)

Background: Meningiomas usually present with a gradual onset of symptoms, and their acute presentation with a hemorrhagic event appears to be a rare condition. Although many clinical features of such a condition have been characterized, pathophysiological mechanisms underlying the bleeding remain unclear, and some contradictory results have been reported. The value of tumor vascularity as an index for the bleeding propensity of meningiomas is inconsistent. We sought to identify whether meningiomas have different types of blood vessels, and to explore the association of the different tumor vessels with intratumoral hemorrhage., Methods: Six patients with meningioma with acute onset due to intratumoral hemorrhage were identified, and 12 nonhemorrhagic meningiomas were matched according to specific clinical data. The characteristics of tumor vessels were examined through immunohistochemical staining of CD31, CD34, and smooth muscle actin (SMA). The number of stained vessels was counted and compared between the 2 groups., Results: Two distinct types of blood vessels were determined in all meningiomas: undifferentiated (CD31 + /CD34 - ) and differentiated (CD31 + /CD34 + ) vessels, and most differentiated vessels were covered by pericytes marked by SMA. However, only the mean number of undifferentiated vessels in hemorrhagic meningiomas was significantly higher than that in controls (15.3 ± 4.9 vs. 6.4 ± 3.6; P < 0.01). Neither the number of differentiated vessels nor the total number of tumor vessels were significantly different between the 2 groups (P > 0.05)., Conclusions: Our results suggest that tumor vasculature in meningiomas is heterogeneous, and that the undifferentiated vessels may play a pivotal role in the spontaneous intratumoral hemorrhage from meningiomas., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Cardiovascular (CV) diseases are becoming increasingly frequent and associated with a high incidence of CV events, disability and death. It is known that there is a relationship between CV burden and systemic autoimmune diseases (SADs) that is mainly due to inflammation and autoimmunity, but the other mechanisms underlying the high CV risk of SAD patients have not yet been fully clarified. The aim of this review article is to discuss some of the specific factors associated with the accelerated atherosclerosis (ATS) characterising SADs (female sex, the microcirculation and the endothelium) in order to highlight the importance of an early diagnosis and the prompt implementation of preventive measures, as well as the possible role of new therapeutic strategies such as vaccine immunomodulation. Finally, as the natural history of ATS begins with endothelial injury (a potentially reversible process that is influenced by various factors) and microvascular damage plays a central role in the etiopathogenesis of SADs, it underlines the crucial need for the development of reliable means of detecting sub-clinical abnormalities in the microcirculation, particularly coronary microcirculation dysfunction., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Objectives: Increased levels of both saturated fatty acids (SFAs) and lipopolysaccharide (LPS) are associated with type 2 diabetes. However, it remains largely unknown how SFAs interact with LPS to regulate inflammatory responses in microvascular endothelial cells (MIC ECs) that are critically involved in atherosclerosis as a diabetic complication. In this study, we compared the effects of LPS, palmitic acid (PA), the most abundant saturated fatty acid, or the combination of LPS and PA on interleukin (IL)-6 expression by MIC ECs and explored the underlying mechanisms., Methods: Human cardiac MIC ECs were treated with LPS, PA and LPS plus PA and the regulatory pathways including receptors, signal transduction, transcription and post-transcription, and sphingolipid metabolism for IL-6 expression were investigated., Results: G protein-coupled receptor (GPR)40 or free fatty acid receptor 1 (FFA1), but not toll-like receptor 4, was involved in PA-stimulated IL-6 expression. PA not only stimulated IL-6 expression by itself, but also remarkably enhanced LPS-stimulated IL-6 expression via a cooperative stimulation on mitogen-activated protein kinase and nuclear factor kappa B signaling pathways, and both transcriptional and post-transcriptional activation. Furthermore, PA induced a robust neutral sphingomyelinase (nSMase)-mediated sphingomyelin hydrolysis that was involved in PA-augmented IL-6 upregulation., Conclusion: PA boosted inflammatory response of microvascular endothelial cells to LPS via GPR40 and nSMase., (Published by Elsevier Ireland Ltd.)

Introduction: Dental pulp stem cells (DPSCs) are suspected to be an important part of the innate immune response of dental pulp, which is triggered by microorganisms that progressively invade the human tooth during the formation of caries. This study was performed to elucidate the expression of toll-like receptor 4 (TLR4) in dental pulp of deep caries and to determine whether TLR4 modulates the proliferation and migration of DPSCs., Methods: Pulp tissue samples were collected from freshly extracted human wisdom tooth. Immunohistochemistry and immunofluorescence were performed to determine the distribution of TLR4 in healthy dental pulp and dental pulp in deep caries. DPSCs were cultured and purified by collecting multiple colonies. The proliferation and migration of DPSCs were examined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, scratch test, and transwell migration assay after stimulation with lipopolysaccharide and extracts from Streptococcus mutans. TLR4 messenger RNA (mRNA) and cytokine mRNA were evaluated with real-time polymerase chain reaction; TLR4 protein was examined with Western blot and immunocytochemistry., Results: TLR4 is expressed in the odontoblast layer and areas that colocalize with blood vessels to different levels in healthy teeth and teeth affected by caries. TLR4 mRNA, TLR4 protein, and mRNA of cytokine levels can be elevated with stimulations of LPS and extracts from S. mutans. Lipopolysaccharide and extracts from S. mutans treatment inhibited the proliferation of DPSCs but promoted migration; however, these changes were abolished when TLR4 was blocked by anti-TLR4 antibody., Conclusions: These results suggest that TLR4 will be activated and regulate the proliferation and migration of DPSCs in deep caries. TLR4 may play an important role in the immune response by DPSCs., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: Observed associations between increased fruit and vegetable (F&V) consumption, particularly those F&Vs that are rich in flavonoids, and vascular health improvements require confirmation in adequately powered randomized controlled trials., Objective: This study was designed to measure the dose-response relation between high-flavonoid (HF), low-flavonoid (LF), and habitual F&V intakes and vascular function and other cardiovascular disease (CVD) risk indicators., Design: A single-blind, dose-dependent, parallel randomized controlled dietary intervention study was conducted. Male and female low-F&V consumers who had a ≥ 1.5-fold increased risk of CVD (n = 174) were randomly assigned to receive an HF F&V, an LF F&V, or a habitual diet, with HF and LF F&V amounts sequentially increasing by 2, 4, and 6 (+2, +4, and +6) portions/d every 6 wk over habitual intakes. Microvascular reactivity (laser Doppler imaging with iontophoresis), arterial stiffness [pulse wave velocity, pulse wave analysis (PWA)], 24-h ambulatory blood pressure, and biomarkers of nitric oxide (NO), vascular function, and inflammation were determined at baseline and at 6, 12, and 18 wk., Results: In men, the HF F&V diet increased endothelium-dependent microvascular reactivity (P = 0.017) with +2 portions/d (at 6 wk) and reduced C-reactive protein (P = 0.001), E-selectin (P = 0.0005), and vascular cell adhesion molecule (P = 0.0468) with +4 portions/d (at 12 wk). HF F&Vs increased plasma NO (P = 0.0243) with +4 portions/d (at 12 wk) in the group as a whole. An increase in F&Vs, regardless of flavonoid content in the groups as a whole, mitigated increases in vascular stiffness measured by PWA (P = 0.0065) and reductions in NO (P = 0.0299) in the control group., Conclusion: These data support recommendations to increase F&V intake to ≥ 6 portions daily, with additional benefit from F&Vs that are rich in flavonoids, particularly in men with an increased risk of CVD.

Introduction: Hofbauer cells (HC) are the placental macrophages that play a significant role in many important placental events. The aim of this retrospective study is to investigate the role of HC in the pathogenesis of early pregnancy loss (EPL)., Methods: The slides were obtained from archival blocks of missed abortion (MA, n = 15) and blighted ovum (BO, n = 15) cases. Unwanted pregnancies materials constituted the control group (n = 15). HC and endothelial cells were identified using immunohistochemical methods. HC were counted under light microscope. The extent of villous vasculature was evaluated using two methods; the Chalkey method and microvessel scoring., Results: The mean number of villous HC was found to be significantly higher in both MA and BO groups in contrast to the control group. MA group also showed a higher number of HC in comparison with the BO group. Higher microvessel scoring was also found in MA group in contrast to other two groups. Chalkey method revealed no significant difference in the extent of villous vasculature for the control group in comparison with MA and BO., Discussion: As we identified relatively low quantity of HC in BO associated with defective vasculature, we hypothesize that an inadequate microvessel formation after hypoxic insult can explain the pathogenesis of BO. We believe that HC are increased in MA due to their divergent roles on immunity and inflammation., Conclusion: We therefore conclude that HC may be of biological importance in the pathogenesis of EPL., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In adult mammals, leukocyte recruitment follows a well-defined cascade of adhesion events enabling leukocytes to leave the circulatory system and transmigrate into tissue. Currently, it is unclear whether leukocyte recruitment proceeds in a similar fashion during fetal development. Considering the fact that the incidence of neonatal sepsis increases dramatically with decreasing gestational age in humans, we hypothesized that leukocyte recruitment may be acquired only late during fetal ontogeny. To test this, we developed a fetal intravital microscopy model in pregnant mice and, using LysEGFP (neutrophil reporter) mice, investigated leukocyte recruitment during fetal development. We show that fetal blood neutrophils acquire the ability to roll and adhere on inflamed yolk sac vessels during late fetal development, whereas at earlier embryonic stages (before day E15), rolling and adhesion were essentially absent. Accordingly, flow chamber experiments showed that fetal EGFP(+) blood cells underwent efficient adhesion only when they were harvested on or after E15. Fluorescence-activated cell sorter analysis on EGFP(+) fetal blood cells revealed that surface expression of CXCR2 and less pronounced P-selectin glycoprotein ligand-1 (PSGL-1) begin to increase only late in fetal life. Taken together, our findings demonstrate that inflammation-induced leukocyte recruitment is ontogenetically regulated and enables efficient neutrophil trafficking only during late fetal life.

Background: Platelets foster an inflammatory environment that influences atherosclerotic lesion progression and facilitates plaque rupture, in addition to their role in acute thrombus formation. The route of entry of platelets into the atherosclerotic plaque and their exact location inside the plaque are however not completely understood., Methods and Results: 188 carotid plaques were examined for the presence of platelets using immunohistochemistry (CD42b), and 76/188 (40.4%) were platelet positive. Platelets were observed in intraplaque hemorrhages, around plaque microvessels, mostly without leakage of erythrocytes; and in mural thrombi. Platelet positive staining was associated with a higher plaque microvessel density, and elevated plaque-levels of interleukin-8., Conclusion: Due to their short life span, platelets reflect recent bleeding. It can be hypothesized that platelets might serve as a marker for leaky microvessels inside atherosclerotic plaques that are at risk for development, or progression of plaque hemorrhage., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Background & Aims: The role of endothelial cells in inflammatory bowel disease has been recently emphasized. Endothelial activation and expression of adhesion molecules are critical for leukocytes recruitment into the inflammatory wall. Compelling evidence demonstrated anti-inflammatory effects of long chain n-3 PUFA in inflammatory models. We previously showed that long chain n-3 PUFA (EPA and DHA) inhibited inflammatory response in epithelial and dendritic cells. As long chain n-3 PUFA treatment led to a decreased expression of adhesion molecules in endothelial cells from other organs, we have now investigated their effect on intestinal endothelial cells in vitro and in colitic rats., Methods: In vitro study: Primary culture of human intestinal microvascular endothelial cells (HIMEC) were pre-treated with DHA and then incubated with IL-1β. In vivo study: Colitis was induced in 2 groups at day0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS). Rats received by gavage either fish oil, rich in EPA and DHA (TNBS+n-3) or an isocaloric isolipidic oil formula for 14 days., Results: DHA led to a decreased VCAM-1, TLR4, cyclooxygenase-2 and VEGFR2 expression and a decreased production of IL-6, IL-8 and GM-CSF and a reduced production of PGE(2) and LTB(4) (p < 0.001) in IL-1β-induced HIMEC. Similarly, dietary intervention with fish oil rich in EPA and DHA significantly decreased colon production of PGE(2) and LTB(4,) endothelial VCAM-1 and VEGFR2 in rats with colitis., Conclusions: Data obtained from in vitro and in vivo studies reveal a potential anti-angiogenic role of long chain n-3 PUFA in intestinal endothelial cells. This protective effect of long chain n-3 PUFA may partly explain the observed benefit of dietary intake of long chain n-3 PUFA in IBD development., (Copyright © 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Interleukin-8 plays a key role in the acute inflammatory response by mediating recruitment of neutrophils through vessel walls into affected tissues. During this process, molecular signals guide circulating blood neutrophils to target specific vessels for extravasation and to migrate through such vessels via particular routes. Our results show that levels of endothelial caveolin-1, the protein responsible for the induction of the membrane domains known as caveolae, are critical to each of these processes. We demonstrate that, in response to the intradermal injection of interleukin-8, neutrophils are preferentially recruited to a unique subset of venules that express high levels of intercellular adhesion molecule-1 and low levels of caveolin-1. Our results show that neutrophils traverse human dermal microvascular endothelial cells using one of two pathways: a transcellular route directly through the cell or a paracellular route through cellular junctions. Caveolin-1 expression appears to favor the transcellular path while down-regulation of caveolin-1 promotes the paracellular route.