Fibrinogen mediates leukocyte adhesion to vascular endothelium through an ICAM-1-dependent pathway

Intercellular Adhesion Molecule 1 (ICAM-1): An Inflammatory Regulator with Potential Implications in Ferroptosis and Parkinson's Disease

Intercellular adhesion molecule 1 (ICAM-1/CD54), a transmembrane glycoprotein, has been considered as one of the most important adhesion molecules during leukocyte recruitment. It is encoded by the ICAM1 gene and plays a central role in inflammation. Its crucial role in many inflammatory diseases such as ulcerative colitis and rheumatoid arthritis are well established. Given that neuroinflammation, underscored by microglial activation, is a key element in neurodegenerative diseases such as Parkinson's disease (PD), we investigated whether ICAM-1 has a role in this progressive neurological condition and, if so, to elucidate the underpinning mechanisms. Specifically, we were interested in the potential interaction between ICAM-1, glial cells, and ferroptosis, an iron-dependent form of cell death that has recently been implicated in PD. We conclude that there exist direct and indirect (via glial cells and T cells) influences of ICAM-1 on ferroptosis and that further elucidation of these interactions can suggest novel intervention for this devastating disease.

Suppressing upregulation of fibrinogen after polytrauma mitigates thrombosis in mice

BACKGROUND

Polytrauma results in systemic inflammation and increased circulating fibrinogen, which increases the risk of microvascular and macrovascular thrombosis that contributes to secondary organ damage and venous thromboembolism (VTE). There are no clinically approved agents to prevent hyperfibrinogenemia after polytrauma. We hypothesized that preventing the increase in fibrinogen levels after polytrauma would suppress thrombosis.

METHODS

Small-interfering ribonucleic acid (siRNA) against fibrinogen was encapsulated in lipid nanoparticles (siFibrinogen). Mice underwent a model of polytrauma and were then given varying doses of siFibrinogen, control siRNA, or no treatment. Fibrinogen was measured for 1 week via enxyme-linked immunosorbent assay (ELISA). To model postinjury VTE, the inferior vena cava was ligated 2 days after polytrauma in a portion of the mice. Thrombus weight was measured 48 hours after the inferior vena cava was ligated.

RESULTS

Treatment with siFibrinogen prevented hyperfibrinogenemia after trauma without exacerbating the hypofibrinogenemic state that occurs in the acute injury period (1 hour). In treated groups, fibrinogen was significantly lower from 6 hours postinjury through the 7-day monitoring period. Maximal fibrinogen reduction was observed at 72 hours. Here, mice that received 2.0 mg/kg of siFibrinogen had 1% of normal values relative to untreated mice, and mice that received 1.0 or 0.5 mg/kg had 4%. Mice treated with siFibrinogen that underwent the postinjury VTE model had significantly reduced thrombus weight compared with control siRNA-treated animals. More notably, among all siFibrinogen treated mice, 12 of 18 were completely protected from thrombosis, compared with 0 of 9 displaying protection in the control group.

CONCLUSION

The rise of fibrinogen and the size of thrombi after polytrauma can be mitigated via the administration of siRNA against fibrinogen. siFibrinogen represents a promising novel target for VTE prophylaxis posttrauma.

Fibrinogen: Structure, abnormalities and laboratory assays

Fibrinogen is the primary precursor protein for the fibrin clot, which is the final target of blood clotting. It is also an acute phase reactant that can vary under physiologic and inflammatory conditions. Disorders in fibrinogen concentration and/or function have been variably linked to the risk of bleeding and/or thrombosis. Fibrinogen assays are commonly used in the management of bleeding as well as the treatment of thrombosis. This chapter examines the structure of fibrinogen, its role in hemostasis as well as in bleeding abnormalities and measurement thereof with respect to clinical management.

Endoplasmic Reticulum Protein 72 Regulates Integrin Mac-1 Activity to Influence Neutrophil Recruitment

BACKGROUND

Integrins mediate the adhesion, crawling, and migration of neutrophils during vascular inflammation. Thiol exchange is important in the regulation of integrin functions. ERp72 (endoplasmic reticulum-resident protein 72) is a member of the thiol isomerase family responsible for the catalysis of disulfide rearrangement. However, the role of ERp72 in the regulation of Mac-1 (integrin αMβ2) on neutrophils remains elusive.

METHODS

Intravital microscopy of the cremaster microcirculation was performed to determine in vivo neutrophil movement. Static adhesion, flow chamber, and flow cytometry were used to evaluate in vitro integrin functions. Confocal fluorescent microscopy and coimmunoprecipitation were utilized to characterize the interactions between ERp72 and Mac-1 on neutrophil surface. Cell-impermeable probes and mass spectrometry were used to label reactive thiols and identify target disulfide bonds during redox exchange. Biomembrane force probe was performed to quantitatively measure the binding affinity of Mac-1. A murine model of acute lung injury induced by lipopolysaccharide was utilized to evaluate neutrophil-associated vasculopathy.

RESULTS

ERp72-deficient neutrophils exhibited increased rolling but decreased adhesion/crawling on inflamed venules in vivo and defective static adhesion in vitro. The defect was due to defective activation of integrin Mac-1 but not LFA-1 (lymphocyte function-associated antigen-1) using blocking or epitope-specific antibodies. ERp72 interacted with Mac-1 in lipid rafts on neutrophil surface leading to the reduction of the C654-C711 disulfide bond in the αM subunit that is critical for Mac-1 activation. Recombinant ERp72, via its catalytic motifs, increased the binding affinity of Mac-1 with ICAM-1 (intercellular adhesion molecule-1) and rescued the defective adhesion of ERp72-deficient neutrophils both in vitro and in vivo. Deletion of ERp72 in the bone marrow inhibited neutrophil infiltration, ameliorated tissue damage, and increased survival during murine acute lung injury.

CONCLUSIONS

Extracellular ERp72 regulates integrin Mac-1 activity by catalyzing disulfide rearrangement on the αM subunit and may be a novel target for the treatment of neutrophil-associated vasculopathy.

Fibrinogen in mice cerebral microvessels induces blood-brain barrier dysregulation with aging via a dynamin-related protein 1-dependent pathway

We previously reported evidence that oxidative stress during aging leads to adverse protein profile changes of brain cortical microvessels (MVs: end arterioles, capillaries, and venules) that affect mRNA/protein stability, basement membrane integrity, and ATP synthesis capacity in mice. As an extension of our previous study, we also found that proteins which comprise the blood-brain barrier (BBB) and regulate mitochondrial quality control were also significantly decreased in the mice's cortical MVs with aging. Interestingly, the neuroinflammatory protein fibrinogen (Fgn) was increased in mice brain MVs, which corresponds with clinical reports indicating that the plasma Fgn concentration increased progressively with aging. In this study, protein-protein interaction network analysis indicated that high expression of Fgn is linked with downregulated expression of both BBB- and mitochondrial fission/fusion-related proteins in mice cortical MVs with aging. To investigate the mechanism of Fgn action, we observed that 2 mg/mL or higher concentration of human plasma Fgn changed cell morphology, induced cytotoxicity, and increased BBB permeability in primary human brain microvascular endothelial cells (HBMECs). The BBB tight junction proteins were significantly decreased with increasing concentration of human plasma Fgn in primary HBMECs. Similarly, the expression of phosphorylated dynamin-related protein 1 (pDRP1) and other mitochondrial fission/fusion-related proteins were also significantly reduced in Fgn-treated HBMECs. Interestingly, DRP1 knockdown by shRNA(h) resulted in the reduction of both BBB- and mitochondrial fission/fusion-related proteins in HBMECs. Our results suggest that elevated Fgn downregulates DRP1, leading to mitochondrial-dependent endothelial and BBB dysfunction in the brain microvasculature.

Anti-inflammatory Effect of Batroxobin Combined With Anticoagulation in Patients With Cerebral Venous Thrombosis

Inflammation is pivotal in the pathogenesis and development of cerebral venous thrombosis (CVT). Herein, we aimed to assess the anti-inflammatory effects of batroxobin combined with anticoagulation in CVT. Participants were categorized into the batroxobin group (batroxobin combined with anticoagulation) and the control group (anticoagulation only). Regression analysis was employed to explore the association between the number of episodes of batroxobin administration and the fluctuation of inflammatory indicators, as well as the proportion of patients with inflammatory indicators that were reduced after batroxobin use. Twenty-three cases (age: 39.9 ± 13.8 years, female: 39.1%) in the batroxobin group and 36 cases (40.3 ± 9.6 years, 52.8%) in the control group were analyzed. Compared to the control group, batroxobin combined with anticoagulation significantly decreased fibrinogen (P < .001), platelet-lymphocyte ratio (PLR) (P = .016) and systemic immune-inflammation index (SII) (P = .008), and increased the proportion of the patients with lower fibrinogen (P < .001), neutrophil-lymphocyte ratio (NLR) (P = .005), PLR (P = .026), and SII (P = .006). Linear analysis showed that as the number of episodes of batroxobin administration increased, the fibrinogen (P < .001), the PLR (P = .001), and the SII (P = .020) significantly decreased. Logistic regression analysis showed as the number of episodes of batroxobin administration increased, the ratio of the patients with decreased NLR (P = .008) and PLR (P = .015), as well as SII (P = .013), significantly increased. Batroxobin could decrease NLR, PLR, and SII in CVT. The effect was related to the number of episodes of batroxobin administration. Besides reducing fibrinogen and indirect thrombolysis effects, this may be another critical benefit of batroxobin for CVT.

A novel co-culture model for investigation of the effects of LPS-induced macrophage-derived cytokines on brain endothelial cells

In order to study effects of macrophage-derived inflammatory mediators associated with systemic inflammation on brain endothelial cells, we have established a co-culture system consisting of bEnd.3 cells and LPS-activated Raw 264.7 cells and performed its cytokine profiling. The cytokine profile of the co-culture model was compared to that of mice treated with intraperitoneal LPS injection. We found that, among cytokines profiled, eight cytokines/chemokines were similarly upregulated in both in vivo mouse and in vitro co-culture model. In contrast to the co-culture model, the cytokine profile of a common mono-culture system consisting of only LPS-activated bEnd.3 cells had little similarity to that of the in vivo mouse model. These results indicate that the co-culture of bEnd.3 cells with LPS-activated Raw 264.7 cells is a better model than the common mono-culture of LPS-activated bEnd.3 cells to investigate the molecular mechanism in endothelial cells, by which systemic inflammation induces neuroinflammation. Moreover, fibrinogen adherence both to bEnd.3 cells in the co-culture and to brain blood vessels in a LPS-treated animal model of Alzheimer's disease increased. To the best of our knowledge, this is the first to utilize bEnd.3 cells co-cultured with LPS-activated Raw 264.7 cells as an in vitro model to investigate the consequence of macrophage-derived inflammatory mediators on brain endothelial cells.

Intercellular Adhesion Molecule 1: More than a Leukocyte Adhesion Molecule

Intercellular adhesion molecule 1 (ICAM-1) is a transmembrane protein in the immunoglobulin superfamily expressed on the surface of multiple cell populations and upregulated by inflammatory stimuli. It mediates cellular adhesive interactions by binding to the β2 integrins macrophage antigen 1 and leukocyte function-associated antigen 1, as well as other ligands. It has important roles in the immune system, including in leukocyte adhesion to the endothelium and transendothelial migration, and at the immunological synapse formed between lymphocytes and antigen-presenting cells. ICAM-1 has also been implicated in the pathophysiology of diverse diseases from cardiovascular diseases to autoimmune disorders, certain infections, and cancer. In this review, we summarize the current understanding of the structure and regulation of the ICAM1 gene and the ICAM-1 protein. We discuss the roles of ICAM-1 in the normal immune system and a selection of diseases to highlight the breadth and often double-edged nature of its functions. Finally, we discuss current therapeutics and opportunities for advancements.

Vascular Effects on Cerebrovascular Permeability and Neurodegeneration

Neurons and glial cells in the brain are protected by the blood brain barrier (BBB). The local regulation of blood flow is determined by neurons and signal conducting cells called astrocytes. Although alterations in neurons and glial cells affect the function of neurons, the majority of effects are coming from other cells and organs of the body. Although it seems obvious that effects beginning in brain vasculature would play an important role in the development of various neuroinflammatory and neurodegenerative pathologies, significant interest has only been directed to the possible mechanisms involved in the development of vascular cognitive impairment and dementia (VCID) for the last decade. Presently, the National Institute of Neurological Disorders and Stroke applies considerable attention toward research related to VCID and vascular impairments during Alzheimer's disease. Thus, any changes in cerebral vessels, such as in blood flow, thrombogenesis, permeability, or others, which affect the proper vasculo-neuronal connection and interaction and result in neuronal degeneration that leads to memory decline should be considered as a subject of investigation under the VCID category. Out of several vascular effects that can trigger neurodegeneration, changes in cerebrovascular permeability seem to result in the most devastating effects. The present review emphasizes the importance of changes in the BBB and possible mechanisms primarily involving fibrinogen in the development and/or progression of neuroinflammatory and neurodegenerative diseases resulting in memory decline.

Oral contraceptive pill (OCP) treatment alters the gene expression of intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) in polycystic ovary syndrome (PCOS) women compared to drug-naive PCOS women

BACKGROUND

Polycystic ovary syndrome (PCOS) presents clinical symptoms of menstrual abnormalities, excessive hair growth (hirsutism), scalp hair loss, acne and infertility. Metabolic abnormalities such as obesity, insulin resistance, glucose intolerance and cardiovascular problems constitute an essential part of PCOS, all of which can have significant long-term health consequences. Low-grade chronic inflammation demonstrated by persistent moderately elevated serum levels of inflammatory and coagulatory markers plays a critical role in the pathogenesis of PCOS. Oral contraceptive pills (OCPs) constitute the mainstay of pharmacologic therapy for women with PCOS to regularize cyclicity and ameliorate androgen excess. On the other hand, OCP use is associated with various venous thromboembolic and proinflammatory events in the general population. PCOS women always carriers the increased lifetime risk of these events. The studies on the effect of OCPs on inflammatory, coagulation and metabolic parameters in PCOS are less robust. Therefore in this study, we investigated and compared the messenger RNA (mRNA) expression profiles of genes implicated in inflammatory and coagulation pathways between drug-naive and OCP-treated PCOS women. The selected genes include intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1). Furthermore, the correlation between the selected markers and various metabolic indices in the OCP group has also been explored.

METHOD

The relative amounts of ICAM-1, TNF-α, MCP-1 and PAI-1 mRNA in peripheral blood mononuclear cells from 25 drug-naive PCOS subjects (controls) and 25 PCOS subjects who received OCPs containing 0.03 mg-ethinyl-estradiol and 0.15 mg-levonorgestrel for at least six months (cases) were estimated using real-time qPCR. The statistical interpretation was conducted using SPSS version 20.0 (SPSS, Inc, Chicago, IL), Epi Info version 2002 (Disease Control and Prevention Centres, Atlanta, GA) and GraphPad Prism 5 (GraphPad Software, La Jolla, CA) software.

RESULT

Six months of OCP therapy enhanced the expression of inflammatory genes viz ICAM-1, TNF-α and MCP-1 mRNA in PCOS women by 2.54, 2.05 and 1.74 folds, respectively, in this study. However, PAI-1 mRNA in the OCP group showed no significant increase. Furthermore, in cases, ICAM-1 mRNA expression positively correlated with body mass index (BMI) (p = 0.01), fasting insulin (p = 0.01), insulin 2 h p = 0.02), glucose 2 h (p = 0.01) and triglycerides (p = 0.01). TNF-α mRNA expression positively correlated with fasting insulin (p = 0.0007). MCP-1 mRNA expression positively correlated with (BMI) (p = 0.002).

CONCLUSION

OCPs helped reduce clinical hyperandrogenism and regularise menstrual cycles in women with PCOS. However, OCP use was associated with increased fold expression of inflammatory markers which positively correlated with metabolic abnormalities.

Fibrinolysis Regulation: A Promising Approach to Promote Osteogenesis

Soon after bone fracture, the initiation of the coagulation cascade results in the formation of a blood clot, which acts as a natural material to facilitate cell migration and osteogenic differentiation at the fracture site. The existence of hematoma is important in early stage of bone healing, but the persistence of hematoma is considered harmful for bone regeneration. Fibrinolysis is recently regarded as a period of critical transition in angiogenic-osteogenic coupling, it thereby is vital for the complete healing of the bone. Moreover, the enhanced fibrinolysis is proposed to boost bone regeneration through promoting the formation of blood vessels, and fibrinolysis system as well as the products of fibrinolysis also play crucial roles in the bone healing process. Therefore, the purpose of this review is to elucidate the fibrinolysis-derived effects on osteogenesis and summarize the potential approaches-improving bone healing by regulating fibrinolysis, with the purpose to further understand the integral roles of fibrinolysis in bone regeneration and to provide theoretical knowledge for potential fibrinolysis-related osteogenesis strategies. Impact statement Fibrinolysis emerging as a new and viable therapeutic intervention to be contained within osteogenesis strategies, however to now, there have been no review articles which collates the information between fibrinolysis and osteogenesis. This review, therefore, focusses on the effects that fibrinolysis exerts on bone healing, with a purpose to provide theoretical reference to develop new strategies to modulate fibrinolysis to accelerate fibrinolysis thus enhancing bone healing.

Current View on the Molecular Mechanisms Underlying Fibrin(ogen)-Dependent Inflammation

Numerous studies have revealed the involvement of fibrinogen in the inflammatory response. To explain the molecular mechanisms underlying fibrinogen-dependent inflammation, two bridging mechanisms have been proposed in which fibrin(ogen) bridges leukocytes to endothelial cells. The first mechanism suggests that bridging occurs via the interaction of fibrinogen with the leukocyte receptor Mac-1 and the endothelial receptor ICAM-1 (intercellular adhesion molecule-1), which promotes leukocyte transmigration and enhances inflammation. The second mechanism includes bridging of leukocytes to the endothelium by fibrin degradation product E1 fragment through its interaction with leukocyte receptor CD11c and endothelial VE-cadherin to promote leukocyte transmigration. The role of E1 in promoting inflammation is inhibited by the fibrin-derived β15-42 fragment, and this has been suggested to result from its ability to compete for the E1-VE-cadherin interaction and to trigger signaling pathways through the src kinase Fyn. Our recent study revealed that the β15-42 fragment is ineffective in inhibiting the E1- or fibrin-VE-cadherin interaction, leaving the proposed signaling mechanism as the only viable explanation for the inhibitory function of β15-42. We have discovered that fibrin interacts with the very-low-density lipoprotein (VLDL) receptor, and this interaction triggers a signaling pathway that promotes leukocyte transmigration through inhibition of the src kinase Fyn. This pathway is inhibited by another pathway induced by the interaction of β15-42 with a putative endothelial receptor. In this review, we briefly describe the previously proposed molecular mechanisms underlying fibrin-dependent inflammation and their advantages/disadvantages and summarize our recent studies of the novel VLDL receptor-dependent pathway of leukocyte transmigration which plays an important role in fibrin-dependent inflammation.

Passive smoking may be associated with bleeding of cerebral arteriovenous malformation in non-smoking women: a retrospective analysis

BACKGROUND

Smoking has been considered to be a risk factor for cardiovascular disease, cancer, depression and other diseases in previous reports, and active smoking is considered to be a risk factor for hemorrhagic stroke. In addition, a retrospective study showed that male smokers were at increased risk of bleeding from arteriovenous malformation (AVM), compared with non-smokers. However, the effect of passive smoking on rupturing of cerebral AVM in non-smoking women has not been addressed.

OBJECTIVE

This study aimed to assess the impact of tobacco exposure on AVM bleeding risk in non-smoking women.

METHODS

A total of 393 non-smoking women diagnosed with AVM were included. They were divided into a bleeding group (205 women) and a non-bleeding group (188 women). We conducted univariate and multivariate analysis on these two groups. In univariate analysis, risk factors that might be related to AVM bleeding were analyzed. In multivariate analysis, the relationship between passive smoking and AVM rupture was analyzed by correcting confounding factors.

RESULTS

Multivariate analysis showed that the proportion of passive smoking was statistically different between the bleeding group and the non-bleeding group (OR = 1.609; CI = 1.031-2.509; p = 0.036).

CONCLUSION

Passive smoking may increase the risk of AVM bleeding in non-smoking women. This increased risk may be related to the inflammatory response, vascular wall damage, hemodynamic disorders, changes in atherosclerosis and changes in gene expression caused by passive smoking.

Impaired Fibrinolysis Is Linked With Digital Vasculopathy and Onset of New Digital Ulcers in Systemic Sclerosis

OBJECTIVE

To assess thrombin generation, fibrin formation, and structure together with the fibrinolytic status in patients with systemic sclerosis (SSc) in relation to the occurrence of digital ulcers (DUs) during the course of disease.

METHODS

We studied variables of endothelial dysfunction, thrombin generation, overall hemostatic potential, and fibrin clot turbidity in plasma from 58 patients with SSc (39 with DU history and 19 DU-naïve) and 46 matched healthy controls (HCs). Fibrin structure was visualized using scanning electron microscopy (SEM). Finally, 39 patients with a history of DUs were followed for 1.5 years and the predictive value of all investigated markers for new DU onset was explored.

RESULTS

Significantly enhanced endogenous thrombin potential (ETP) and prolonged clot lysis time (CLT) were found in patients with DUs compared to HCs. CLT was prolonged in patients with DUs compared to those without, showing good validity in identifying DUs with an area under the curve of 0.7 (95% CI 0.6-0.8). The levels of ETP and intercellular adhesion molecule 1 were independently associated with CLT. Over the follow-up period, 20 patients developed new DUs. CLT was prolonged (P < 0.001) in patients with new DU episodes, especially those with recurrent DUs. Regression analysis showed that the Raynaud phenomenon visual analog scale and CLT were predictors of new DUs (OR 1.1, 95% CI 1.0-1.1 and OR 1.2, 95% CI 1.1-1.3, respectively). SEM confirmed denser fibrin clots in patients with new DUs.

CONCLUSION

Our results suggest that impaired fibrinolysis might have an emerging role in underlying digital vasculopathy and its progression in SSc.

CCR2 monocytes repair cerebrovascular damage caused by chronic social defeat stress

Immune surveillance of the brain plays an important role in health and disease. Peripheral leukocytes patrol blood-brain barrier interfaces, and after injury, monocytes cross the cerebrovasculature and follow a pattern of pro- and anti-inflammatory activity leading to tissue repair. We have shown that chronic social defeat (CSD) causes scattered vasculature disruptions. Here, we assessed CCR2⁺ monocyte trafficking to the vascular injury sites in Ccr2^wt/rfp reporter mice both during CSD and one week following CSD cessation. We found that CSD for 14 days induced microhemorrhages where plasma fibrinogen leaked into perivascular spaces, but it did not affect the distribution or density of CCR2^rfp+ monocytes in the brain. However, after recovery from CSD, many vascularly adhered CCR2⁺ cells were detected, and gene expression of the CCR2 chemokine receptor ligands CCL7 and CCL12, but not CCL2, was elevated in endothelial cells. Adhered CCR2⁺ cells were mostly the non-classical, anti-inflammatory Ly6C^lo type, and they phagocytosed fibrinogen in perivascular spaces. In CCR2-deficient Ccr2^rfp/rfp mice, fibrinogen levels remained elevated in recovery. Fibrinogen infused intracerebroventricularly induced CCR2⁺ cells to adhere to the vasculature and phagocytose perivascular fibrinogen in Ccr2^wt/rfp but not Ccr2^rfp/rfp mice. Depletion of monocytes with clodronate liposomes during CSD recovery prevented fibrinogen clearance and blocked behavioral recovery. We hypothesize that peripheral CCR2⁺ monocytes are not elevated in the brain on day 14 at the end of CSD and do not contribute to its behavioral effects at that time, but in recovery following cessation of stress, they enter the brain and exert restorative functions mediating vascular repair and normalization of behavior.

IL-1β Impacts Vascular Integrity and Lymphatic Function in the Embryonic Omentum

BACKGROUND

The chromatin-remodeling enzyme BRG1 (brahma-related gene 1) regulates gene expression in a variety of rapidly differentiating cells during embryonic development. However, the critical genes that BRG1 regulates during lymphatic vascular development are unknown.

METHODS

We used genetic and imaging techniques to define the role of BRG1 in murine embryonic lymphatic development, although this approach inadvertently expanded our study to multiple interacting cell types.

RESULTS

We found that omental macrophages fine-tune an unexpected developmental process by which erythrocytes escaping from naturally discontinuous omental blood vessels are collected by nearby lymphatic vessels. Our data indicate that circulating fibrin(ogen) leaking from gaps in omental blood vessels can trigger inflammasome-mediated IL-1β (interleukin-1β) production and secretion from nearby macrophages. IL-1β destabilizes adherens junctions in omental blood and lymphatic vessels, contributing to both extravasation of erythrocytes and their uptake by lymphatics. BRG1 regulates IL-1β production in omental macrophages by transcriptionally suppressing the inflammasome trigger RIPK3 (receptor interacting protein kinase 3).

CONCLUSIONS

Genetic deletion of Brg1 in embryonic macrophages leads to excessive IL-1β production, erythrocyte leakage from blood vessels, and blood-filled lymphatics in the developing omentum. Altogether, these results highlight a novel context for epigenetically regulated crosstalk between macrophages, blood vessels, and lymphatics.

Fibrin(ogen) engagement of S. aureus promotes the host antimicrobial response and suppression of microbe dissemination following peritoneal infection

The blood-clotting protein fibrin(ogen) plays a critical role in host defense against invading pathogens, particularly against peritoneal infection by the Gram-positive microbe Staphylococcus aureus. Here, we tested the hypothesis that direct binding between fibrin(ogen) and S. aureus is a component of the primary host antimicrobial response mechanism and prevention of secondary microbe dissemination from the peritoneal cavity. To establish a model system, we showed that fibrinogen isolated from Fibγ^Δ5 mice, which express a mutant form lacking the final 5 amino acids of the fibrinogen γ chain (termed fibrinogenγ^Δ5), did not support S. aureus adherence when immobilized and clumping when in suspension. In contrast, purified wildtype fibrinogen supported robust adhesion and clumping that was largely dependent on S. aureus expression of the receptor clumping factor A (ClfA). Following peritoneal infection with S. aureus USA300, Fibγ^Δ5 mice displayed worse survival compared to WT mice coupled to reduced bacterial killing within the peritoneal cavity and increased dissemination of the microbes into circulation and distant organs. The failure of acute bacterial killing, but not enhanced dissemination, was partially recapitulated by mice infected with S. aureus USA300 lacking ClfA. Fibrin polymer formation and coagulation transglutaminase Factor XIII each contributed to killing of the microbes within the peritoneal cavity, but only elimination of polymer formation enhanced systemic dissemination. Host macrophage depletion or selective elimination of the fibrin(ogen) β2-integrin binding motif both compromised local bacterial killing and enhanced S. aureus systemic dissemination, suggesting fibrin polymer formation in and of itself was not sufficient to retain S. aureus within the peritoneal cavity. Collectively, these findings suggest that following peritoneal infection, the binding of S. aureus to stabilized fibrin matrices promotes a local, macrophage-mediated antimicrobial response essential for prevention of microbe dissemination and downstream host mortality.

The Gram-positive bacterium Staphylococcus aureus (S. aureus) produces a number of soluble and surface-associated proteins that bind the host coagulation protein fibrinogen. The contribution of fibrinogen-S. aureus binding through the fibrinogen receptor clumping factor A (ClfA) in peritoneal infection has not been defined. Elimination of the binding motif on fibrinogen for ClfA or deletion of ClfA from S. aureus significantly reduced S. aureus-fibrinogen binding and bacterial clumping in solution. In a mouse model of peritonitis, loss of these activities resulted in diminished bacterial killing, increased bacterial dissemination, and worsened host survival. Although fibrin polymer formation and fibrin(ogen)-macrophage binding are mechanistically linked to the local antimicrobial response, fibrin formation in and of itself is not sufficient to suppress microbe dissemination. These discoveries have identified important components of the fibrin(ogen)-dependent host antimicrobial response against S. aureus, providing further understanding of this physiological response to infection which could uncover potential therapeutic strategies for peritonitis patients.

Gα13 Mediates Transendothelial Migration of Neutrophils by Promoting Integrin-Dependent Motility without Affecting Directionality

Neutrophil migration requires β₂ integrins and chemoattractant receptor signaling for motility and directionality. G protein subunit Gα₁₃ can facilitate cell migration by mediating RhoA activation induced by G protein-coupled receptors. However, the possible role of Gα₁₃-integrin interaction in migration is unclear. In this study, we show that Gα₁₃ ^-/- neutrophils are deficient in transendothelial migration and migration on β₂ integrin ligand ICAM-1. However, unlike G protein-coupled receptors and integrin inside-out signaling pathways, Gα₁₃ is important in migration velocity and neutrophil spreading but not in directionality nor cell adhesion. Importantly, neutrophil recruitment in vivo was also inhibited in Gα₁₃ ^-/- mice, suggesting the importance of Gα₁₃ in transendothelial migration of neutrophils in vitro and in vivo. Furthermore, a synthetic peptide (MB2mP6) derived from the Gα₁₃ binding site of β₂ inhibited Gα₁₃-β₂ interaction and Gα₁₃-mediated transient RhoA inhibition in neutrophils, suggesting that this peptide inhibited integrin outside-in signaling. MB2mP6 inhibited migration of control neutrophils through endothelial cell monolayers or ICAM-1-coated filters, but was without further effect on Gα₁₃ ^-/- neutrophils. It also inhibited integrin-dependent neutrophil migration velocity without affecting directionality. In vivo, MB2mP6 markedly inhibited neutrophil infiltration into the cardiac tissues induced by ischemia/reperfusion injury. Thus, Gα₁₃-dependent outside-in signaling enables integrin-dependent neutrophil motility without affecting directionality and may be a new therapeutic target for inhibiting neutrophil trafficking but not adhesion.

Gene regulation of intracellular adhesion molecule-1 (ICAM-1): A molecule with multiple functions

Intracellular adhesion molecule 1 (ICAM-1) is one of the most extensively studied inducible cell adhesion molecules which is responsible for several immune functions like T cell activation, extravasation, inflammation, etc. The molecule is constitutively expressed over the cell surface and is regulated up / down in response to inflammatory mediators like cellular stress, proinflammatory cytokines, viral infection. These stimuli modulate the expression of ICAM-1 primarily through regulating the ICAM-1 gene transcription. On account of the presence of various binding sites for NF-κB, AP-1, SP-1, and many other transcription factors, the architecture of the ICAM-1 promoter become complex. Transcription factors in union with other transcription factors, coactivators, and suppressors promote their assembly in a stereospecific manner on ICAM-1 promoter which mediates ICAM-1 regulation in response to different stimuli. Along with transcriptional regulation, epigenetic modifications also play a pivotal role in controlling ICAM-1 expression on different cell types. In this review, we summarize the regulation of ICAM-1 expression both at the transcriptional as well as post-transcriptional level with an emphasis on transcription factors and signaling pathways involved.

Vitronectin stabilizes intravascular adhesion of neutrophils by coordinating β2 integrin clustering

The recruitment of neutrophils from the microvasculature to the site of injury or infection represents a key event in the inflammatory response. Vitronectin (VN) is a multifunctional macromolecule abundantly present in blood and extracellular matrix. The role of this glycoprotein in the extravasation process of circulating neutrophils remains elusive. Employing advanced in vivo/ex vivo imaging techniques in different mouse models as well as in vitro methods, we uncovered a previously unrecognized function of VN in the transition of dynamic to static intravascular interactions of neutrophils with microvascular endothelial cells. These distinct properties of VN require the heteromerization of this glycoprotein with plasminogen activator inhibitor-1 (PAI- 1) on the activated venular endothelium and subsequent interactions of this protein complex with the scavenger receptor low-density lipoprotein receptor-related protein-1 on intravascularly adhering neutrophils. This induces p38 mitogen-activated protein kinases-dependent intracellular signaling events which, in turn, regulates the proper clustering of the b2 integrin lymphocyte function associated antigen-1 on the surface of these immune cells. As a consequence of this molecular interplay, neutrophils become able to stabilize their adhesion to the microvascular endothelium and, subsequently, to extravasate to the perivascular tissue. Hence, endothelial-bound VN-PAI-1 heteromers stabilize intravascular adhesion of neutrophils by coordinating b2 integrin clustering on the surface of these immune cells, thereby effectively controlling neutrophil trafficking to inflamed tissue. Targeting this protein complex might be beneficial for the prevention and treatment of inflammatory pathologies.

The Effects of Fibrinogen's Interactions with Its Neuronal Receptors, Intercellular Adhesion Molecule-1 and Cellular Prion Protein

Neuroinflammatory diseases, such as Alzheimer's disease (AD) and traumatic brain injury (TBI), are associated with the extravascular deposition of the fibrinogen (Fg) derivative fibrin and are accompanied with memory impairment. We found that during the hyperfibrinogenemia that typically occurs during AD and TBI, extravasated Fg was associated with amyloid beta and astrocytic cellular prion protein (PrPC). These effects coincided with short-term memory (STM) reduction and neurodegeneration. However, the mechanisms of a direct Fg-neuron interaction and its functional role in neurodegeneration are still unclear. Cultured mouse brain neurons were treated with Fg in the presence or absence of function-blockers of its receptors, PrPC or intercellular adhesion molecule-1 (ICAM-1). Associations of Fg with neuronal PrPC and ICAM-1 were characterized. The expression of proinflammatory marker interleukin 6 (IL-6) and the generation of reactive oxygen species (ROS), mitochondrial superoxide, and nitrite in neurons were assessed. Fg-induced neuronal death was also evaluated. A strong association of Fg with neuronal PrPC and ICAM-1, accompanied with overexpression of IL-6 and enhanced generation of ROS, mitochondrial superoxide, and nitrite as well as the resulting neuronal death, was found. These effects were reduced by blocking the function of neuronal PrPC and ICAM-1, suggesting that the direct interaction of Fg with its neuronal receptors can induce overexpression of IL-6 and increase the generation of ROS, nitrite, and mitochondrial superoxide, ultimately leading to neuronal death. These effects can be a mechanism of neurodegeneration and the resultant memory reduction seen during TBI and AD.

Structural Basis for the Interaction of Fibrin with the Very Low-Density Lipoprotein Receptor Revealed by NMR and Site-Directed Mutagenesis

Interaction of fibrin with the very low-density lipoprotein receptor (VLDLR) promotes transendothelial migration of leukocytes and thereby inflammation. To establish the structural basis for this interaction, we have previously localized the VLDLR-binding site to fibrin βN-domains including fibrin β chain sequence 15-64 and determined the NMR solution structure of the VLDLR(2-4) fragment containing fibrin-binding CR domains 2-4 of VLDLR. In this study, we identified amino acid residues in VLDLR and the βN-domains that are involved in the interaction using NMR and site-directed mutagenesis. The results obtained revealed that Lys47 and Lys53 of the second and third positively charged clusters of the βN-domain, respectively, interact with Trp20 and Asp25 of the CR2 domain and Trp63 and Glu68 of the CR3 domain, respectively. This finding indicates that Lys residues of the βN-domain interact with the Lys-binding site of the CR domains in a manner proposed earlier for the interaction of other members of the LDL receptor family with their ligands. In addition, Gly15 of the βN-domain and its first positively charged cluster contribute to the high-affinity interaction with VLDLR. Molecular modeling based on the results obtained and analysis of the previously published structures of such domains complexed with RAP and HRV2 allowed us to propose a model of interaction of fibrin βN-domains with the fibrin-binding CR domains of the VLDL receptor.

Induction of the CD24 Surface Antigen in Primary Undifferentiated Human Adipose Progenitor Cells by the Hedgehog Signaling Pathway

In the murine model system of adipogenesis, the CD24 cell surface protein represents a valuable marker to label undifferentiated adipose progenitor cells. Indeed, when injected into the residual fat pads of lipodystrophic mice, these CD24 positive cells reconstitute a normal white adipose tissue (WAT) depot. Unluckily, similar studies in humans are rare and incomplete. This is because it is impossible to obtain large numbers of primary CD24 positive human adipose stem cells (hASCs). This study shows that primary hASCs start to express the glycosylphosphatidylinositol (GPI)-anchored CD24 protein when cultured with a chemically defined medium supplemented with molecules that activate the Hedgehog (Hh) signaling pathway. Therefore, this in vitro system may help understand the biology and role in adipogenesis of the CD24-positive hASCs. The induced cells’ phenotype was studied by flow cytometry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) techniques, and their secretion profile. The results show that CD24 positive cells are early undifferentiated progenitors expressing molecules related to the angiogenic pathway.

BCR activated CLL B cells use both CR3 (CD11b/CD18) and CR4 (CD11c/CD18) for adhesion while CR4 has a dominant role in migration towards SDF-1

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in the western world. In previous studies, various proportion of patients was found to carry CD11b+ or CD11c+ B cells whose presence was an unfavourable prognostic factor. The exact mechanism however, how these receptors contribute to the pathogenesis of CLL has not been revealed so far. Here we analysed the role of CD11b and CD11c on B cells of CLL patients in the adhesion to fibrinogen and in the migration towards stromal cell derived factor-1 (SDF-1) and studied the role of CR4 in the adherence of the CD11c+ B cell line BJAB. We observed that both CR3 and CR4 mediate adhesion of the malignant B cells. Moreover, we found, that CR4 was strongly involved in the migration of the leukemic cells towards the chemoattractant SDF-1. Our data suggest that CR3 and CR4 are not only passive markers on CLL B cells, but they might contribute to the progression of the disease. Since the role of SDF-1 is prominent in the migration of CLL cells into the bone marrow where their survival is supported, our findings help to understand how the presence of CD11c on leukemic B cells can worsen the prognosis of chronic lymphocytic leukaemia.

Thrombin generation and activity in multiple sclerosis

The coagulation cascade and immune system are intricately linked, highly regulated and respond cooperatively in response to injury and infection. Increasingly, evidence of hyper-coagulation has been associated with autoimmune disorders, including multiple sclerosis (MS). The pathophysiology of MS includes immune cell activation and recruitment to the central nervous system (CNS) where they degrade myelin sheaths, leaving neuronal axons exposed to damaging inflammatory mediators. Breakdown of the blood-brain barrier (BBB) facilitates the entry of peripheral immune cells. Evidence of thrombin activity has been identified within the CNS of MS patients and studies using animal models of experimental autoimmune encephalomyelitis (EAE), suggest increased thrombin generation and activity may play a role in the pathogenesis of MS as well as inhibit remyelination processes. Thrombin is a serine protease capable of cleaving multiple substrates, including protease activated receptors (PARs), fibrinogen, and protein C. Cleavage of all three of these substrates represent pathways through which thrombin activity may exert immuno-regulatory effects and regulate permeability of the BBB during MS and EAE. In this review, we summarize evidence that thrombin activity directly, through PARs, and indirectly, through fibrin formation and activation of protein C influences neuro-immune responses associated with MS and EAE pathology.

Fibrinogen Interaction with Astrocyte ICAM-1 and PrPC Results in the Generation of ROS and Neuronal Death

Many neuroinflammatory diseases, like traumatic brain injury (TBI), are associated with an elevated level of fibrinogen and short-term memory (STM) impairment. We found that during TBI, extravasated fibrinogen deposited in vasculo-astrocyte interfaces, which was associated with neurodegeneration and STM reduction. The mechanisms of this fibrinogen-astrocyte interaction and its functional role in neurodegeneration are still unclear. Cultured mouse brain astrocytes were treated with fibrinogen in the presence or absence of function-blocking antibody or peptide against its astrocyte receptors intercellular adhesion molecule-1 (ICAM-1) or cellular prion protein (PrP^C), respectively. Fibrinogen interactions with astrocytic ICAM-1 and PrP^C were characterized. The expression of pro-inflammatory markers, generations of reactive oxygen species (ROS) and nitric oxide (NO) in astrocytes, and neuronal death caused by astrocyte-conditioned medium were assessed. Data showed a strong association between fibrinogen and astrocytic ICAM-1 or PrP^C, overexpression of pro-inflammatory cytokines and overproduction of ROS and NO, resulting in neuronal apoptosis and death. These effects were reduced by blocking the function of astrocytic ICAM-1 and PrP^C, suggesting that fibrinogen association with its astrocytic receptors induce the release of pro-inflammatory cytokines, resulting in oxidative stress, and ultimately neuronal death. This can be a mechanism of neurodegeneration and the resultant STM reduction seen during TBI.

Nomograms based on clinicopathological factors and inflammatory indicators for prediction of early and late recurrence of hepatocellular carcinoma after surgical resection for patients with chronic hepatitis B

Background

Few studies have focused on the prognostic values of inflammation-related factors for different phases of recurrence in hepatocellular carcinoma (HCC). We aimed to identify the different risk factors for overall, early, and late recurrence, and to establish nomograms based on inflammation-related parameters for predicting the risks of recurrence in a group of HCC patients undergoing hepatectomy.

Methods

We retrospectively enrolled 383 HCC patients with chronic hepatitis B (CHB) who underwent hepatectomy. Univariate and multivariate Cox analyses were conducted to identify independent risk factors for recurrence. Nomograms for overall, early, and late recurrence-free survival (RFS) were established. The discrimination and calibration abilities of the nomograms were evaluated by concordance indexes (C-index), calibration plots, and Kaplan-Meier curves. Finally, receiver operating characteristic (ROC) curves were used to compare the derived nomograms with other existing models.

Results

Fibrinogen, lymphocyte-to-monocyte ratio, and S-index inflammation-related factors were independently related to overall and early RFS, but only the S-index correlated with late recurrence. Nomograms with tumor number, diameter, and pathological differentiation for overall and early RFS were established, while nomogram for late recurrence was constructed with tumor number and Child-Pugh grade. The C-indexes for overall, early, and late RFS were 0.679, 0.677, and 0.728, respectively. The calibration plots fit well. The nomograms showed superior discrimination capacities and better performance prediction with larger areas under the curve for recurrence.

Conclusions

The developed nomograms that integrated inflammation-related factors showed high predictive accuracy for overall, early, and late recurrence in HCC patients with CHB after hepatectomy.

A critical role for plasminogen in inflammation

Plasminogen and its active form, plasmin, have diverse functions related to the inflammatory response in mammals. Due to these roles in inflammation, plasminogen has been implicated in the progression of a wide range of diseases with an inflammatory component. In this review, we discuss the functions of plasminogen in inflammatory regulation and how this system plays a role in the pathogenesis of diseases spanning organ systems throughout the body.

Is smoking a risk factor for bleeding in adult men with cerebral arteriovenous malformations? A single-center regression study from China

OBJECTIVE

To assess whether smoking increases the risk of bleeding in patients with cerebral arteriovenous malformations (CAVM).

MATERIAL AND METHODS

According to our research plan, 385 CAVM patients admitted to Beijing Tiantan Hospital from December 2015 to January 2018 were included in this study, including 210 bleeding patients and 175 non-bleeding patients. We divided patients into three subgroups of current smokers, ex-smokers (those who quit smoking for one year or more) and non-smokers. The relationship between smoking and the risk of CAVM rupture was assessed by univariate and multivariate regression analysis.

RESULTS

Multivariate regression analysis showed that there was a statistically significant difference between current smoker and non-smoker (OR = 1.87, p = 0.019). Among the covariates of the multivariate regression analysis, the location, combined with blood flow-related intracranial aneurysms and size were related to the risk of CAVM bleeding.

CONCLUSION

Current smoking may increase the risk of CAVM bleeding; however, there was no significant correlation between ex-smoking and CAVM bleeding.

Effect of Coagulation Factor Concentrates on Markers of Endothelial Cell Damage in Experimental Hemorrhagic Shock

BACKGROUND

Plasma-based resuscitation showed protective effects on the endothelial glycocalyx compared with crystalloid resuscitation. There is paucity of data regarding the effect of coagulation factor concentrates (CFC) on the glycocalyx in hemorrhagic shock (HS). We hypothesized that colloid-based resuscitation supplemented with CFCs offers a therapeutic value to treat endothelial damage following HS.

METHODS

Eighty-four rats were subjected to pressure-controlled (mean arterial pressure (MAP) 30-35 mm Hg) and lab-guided (targeted cutoff: lactate >2.2. mmol/L and base deficit > 5.5 mmol/L) HS. Animals were resuscitated with fresh frozen plasma (FFP), human albumin (HA) or Ringer's lactate (RL) and RL or HA supplemented with fibrinogen concentrate (FC) or prothrombin complex concentrate (PCC). Serum epinephrine and the following markers of endothelial damage were assessed at baseline and at the end-of-observation (120 min after shock was terminated): syndecan-1, heparan sulfate, and soluble vascular endothelial growth factor receptor 1 (sVEGFR 1).

RESULTS

Resuscitation with FFP had no effect on sVEGFR1 compared with crystalloid-based resuscitation (FFP: 19.3 ng/mL vs. RL: 15.9 ng/mL; RL+FC: 19.7 ng/mL; RL+PCC: 18.9 ng/mL; n.s.). At the end-of-observation, syndecan-1 was similar among all groups. Interestingly, HA+FC treated animals displayed the highest syndecan-1 concentration (12.07 ng/mL). Resuscitation with FFP restored heparan sulfate back to baseline (baseline: 36 ng/mL vs. end-of-observation: 36 ng/mL).

CONCLUSION

The current study revealed that plasma-based resuscitation normalized circulating heparan sulfate but not syndecan-1. Co-administration of CFC had no further effect on glycocalyx shedding suggesting a lack of its therapeutic potential.

LEVEL OF EVIDENCE

VExperimental in vivo study.

Fibrinogen and Neuroinflammation During Traumatic Brain Injury

Many neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis, and traumatic brain injury (TBI) are associated with systemic inflammation. Inflammation itself results in increased blood content of fibrinogen (Fg), called hyperfibrinogenemia (HFg). Fg is not only considered an acute phase protein and a marker of inflammation, but has been shown that it can cause inflammatory responses. Fibrin deposits have been associated with memory reduction in neuroinflammatory diseases such as AD and TBI. Reduction in short-term memory has been seen during the most common form of TBI, mild-to-moderate TBI. Fibrin deposits have been found in brains of patients with mild-to-moderate TBI. The vast majority of the literature emphasizes the role of fibrin-activated microglia as the mediator in the neuroinflammation pathway. However, the recent discovery that astrocytes, which constitute approximately 30% of the cells in the mammalian central nervous system, manifest different reactive states warrants further investigations in the causative role of HFg in astrocyte-mediated neuroinflammation. Our previous study showed that Fg deposited in the vasculo-astrocyte interface-activated astrocytes. However, little is known of how Fg directly affects astrocytes and neurons. In this review, we summarize studies that show the effect of Fg on different types of cells in the vasculo-neuronal unit. We will also discuss the possible mechanism of HFg-induced neuroinflammation during TBI.

The human liver matrisome - Proteomic analysis of native and fibrotic human liver extracellular matrices for organ engineering approaches

The production of biomaterials that endow significant morphogenic and microenvironmental cues for the constitution of cell integration and regeneration remains a key challenge in the successful implementation of functional organ replacements. Despite the vast development in the production of biological and architecturally native matrices, the complex compositions and pivotal figures by which the human matrisome mediates many of its essential functions are yet to be defined. Here we present a thorough analysis of the native human liver proteomic landscape using decellularization and defatting protocols to create extracellular matrix scaffolds of natural origin that can further be used in both bottom-up and top-down approaches in tissue engineering based organ replacements. Furthermore, by analyzing human liver extracellular matrices in different stages of fibrosis and cirrhosis, we have identified distinct attributes of these tissues that could potentially be exploited therapeutically and thus require further investigation. The general experimental pipeline presented in this study is applicable to any type of tissue and can be widely used for different approaches in regenerative medicine and in the construction of novel biomaterials for organ engineering approaches.

Preoperative elevated plasma fibrinogen level predicts tumor recurrence and poor prognosis in patients with hepatocellular carcinoma

Background

Elevated plasma fibrinogen has been reported to be associated with poor prognosis in several cancers. The aim of present study was to investigate the prognostic value of preoperative plasma fibrinogen in hepatocellular carcinoma (HCC) patients.

Methods

Data were collected retrospectively from 302 HCC patients who received hepatectomy. The association between fibrinogen and clinicopathological characteristics was evaluated. Both univariate and multivariate analyses were performed to identify prognostic factors for disease-free survival (DFS) and overall survival (OS). And accordingly, the nomograms were constructed.

Results

Elevated plasma fibrinogen (>4 g/L) was correlated with larger tumor diameter, the presence of vascular invasion, lower MELD score, higher NLR, advanced Barcelona Clinic Liver Cancer stage and poor-moderate pathological differentiation. On multivariate analysis, the elevated plasma fibrinogen was found independently associated with poor DFS (HR =1.575, P=0.024) and OS (HR =2.051, P=0.025). And the nomograms including fibrinogen were constructed to predict DFS and OS for HCC patients. Both DFS and OS in patients with plasma fibrinogen >4 g/L were significantly lower than those with fibrinogen ≤4 g/L (1-, 3-, 5-year DFS: 34.2%, 19.5% and 0.0% vs. 60.4%, 34.2% and 30.2%; 1-, 3-, 5-year OS: 83.4%, 62.7% and 48.8% vs. 95.4%, 84.3% and 75.8%, both P<0.001). Besides, subgroup analyses also showed the prognostic values of fibrinogen in HCC patients with/without cirrhosis or high AFP levels, and in those with single tumor and BCLC 0-A stage.

Conclusions

Preoperative elevated plasma fibrinogen was an independent prognostic factor associated with poor prognosis in HCC patients receiving liver resection.

In situ condensation of an anti-cancer drug into fibrin gel enabling effective inhibition of tumor cell growth

We show herein the highly effective inhibition of tumor cell growth using a gel consisting of a fibrin polymer formed with the in situ condensation of a camptothecin (CPT) derivative as an anti-cancer drug, which is efficiently conveyed with a carrier aptamer from a solution to the gel in a phenomenon, called selective oligonucleotide entrapment in fibrin polymers (SOEF).

Fibrin-VLDL Receptor-Dependent Pathway Promotes Leukocyte Transmigration by Inhibiting Src Kinase Fyn and is a Target for Fibrin β15-42 Peptide

According to the current view, binding of fibrin degradation product E₁ fragment to endothelial VE-cadherin promotes transendothelial migration of leukocytes and thereby inflammation, and fibrin-derived β15-42 peptide reduces leukocyte transmigration by competing with E₁ for binding to VE-cadherin and, in addition, by signaling through Src kinase Fyn. However, the very low affinity of β15-42 to VE-cadherin raised a question about its ability to inhibit E₁-VE-cadherin interaction. Further, our previous study revealed that fibrin promotes leukocyte transmigration through the very-low-density lipoprotein (VLDL) receptor (VLDLR)-dependent pathway and suggested a possible link between the inhibitory properties of β15-42 and this pathway. To test such a link and the proposed inhibitory mechanisms for β15-42, we performed in vitro experiments using surface plasmon resonance, enzyme-linked immunosorbent assay, and leukocyte transendothelial migration assay, and in vivo studies with wild-type and VLDLR-deficient mice using mouse model of peritonitis. The experiments revealed that β15-42 cannot inhibit E₁-VE-cadherin interaction at the concentrations used in the previous in vivo studies leaving the proposed Fyn-dependent signaling mechanism as a viable explanation for the inhibitory effect of β15-42. While testing this mechanism, we confirmed that Fyn plays a critical role in controlling fibrin-induced transendothelial migration of leukocytes and found that signaling through the VLDLR-dependent pathway results in inhibition of Fyn, thereby increasing leukocyte transmigration. Furthermore, our in vivo experiments revealed that β15-42 inhibits this pathway, thereby preventing inhibition of Fyn and reducing leukocyte transmigration. Thus, this study clarifies the molecular mechanism underlying the VLDLR-dependent pathway of leukocyte transmigration and reveals that this pathway is a target for β15-42.

The role of PSGL-1 in pathogenesis of systemic inflammatory response and coagulopathy in endotoxemic mice

INTRODUCTION

Endotoxemia often results in systemic inflammatory response syndrome (SIRS), coagulation disturbance and acute lung injury (ALI), and such a condition is associated with the activation of platelets, leukocytes and vascular endothelial cells (VECs). P-selectin glycoprotein ligand 1 (PSGL-1) is a key regulatory molecule in the activation of platelets, leukocytes and VECs. However, it still remains largely unexplored whether PSGL-1 plays an important role in SIRS, coagulation dysfunction and ALI of endotoxemia. In the present study, we aimed to study the role of PSGL-1 in above-mentioned situations using endotoxemic mice.

MATERIALS AND METHODS

An endotoxemia model was established in BALB/c mice via lipopolysaccharide (LPS) administration. Moreover, the mice were simultaneously injected with PSGL-1 antibody for intervention. The survival rate, morphologic changes of lung tissues, platelet-leukocyte adhesion, tissue factor expression on leukocytes, fibrinogen deposition in lung tissues, serum levels of inflammatory factors and the activation of VECs were determined.

RESULTS

The results showed that the aggregation and recruitment of platelets and leukocytes in lung tissues, the expression of tissue factor on leukocytes, the serum levels of inflammatory factors, the activation of VECs, and the fibrinogen deposition in lung tissues were increased in endotoxemic mice, which were significantly alleviated by administration of PSGL-1 antibody. Moreover, blockade of PSGL-1 markedly increased survival rate, and alleviated coagulation disturbance and lung injury in endotoxemic mice.

CONCLUSIONS

Taken together, PSGL-1 played an important role in pathogenesis of SIRS and coagulation dysfunction and ALI in endotoxemic mice.

Fibrinolysis and Inflammation in Venous Thrombus Resolution

Clinical observations and accumulating laboratory evidence support a complex interplay between coagulation, inflammation, innate immunity and fibrinolysis in venous thromboembolism (VTE). VTE, which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), and the subsequent complications of post-thrombotic syndrome (PTS), are significant causes of morbidity and mortality in patients. Clinical risk factors for VTE include cancer, major trauma, surgery, sepsis, inflammatory bowel disease, paralysis, prolonged periods of immobility, and aging. Abnormalities in venous blood flow or stasis initiates the activation of endothelial cells, and in concert with platelets, neutrophils and monocytes, propagates VTE in an intact vein. In addition, inflammatory cells play crucial roles in thrombus recanalization and restoration of blood flow via fibrinolysis and vascular remodeling. Faster resolution of the thrombus is key for improved disease prognosis. While in the clinical setting, anticoagulation therapy is successful in preventing propagation of venous thrombi, current therapies are not designed to inhibit inflammation, which can lead to the development of PTS. Animal models of DVT have provided many insights into the molecular and cellular mechanisms involved in the formation, propagation, and resolution of venous thrombi as well as the roles of key components of the fibrinolytic system in these processes. Here, we review the recent advances in our understanding of fibrinolysis and inflammation in the resolution of VTE.

Extracellular Matrix Interactions with Gram-Positive Pathogens

The main strategies used by pathogenic bacteria to infect eukaryotic tissue include their adherence to cells and the extracellular matrix (ECM), the subsequent colonization and invasion as well as the evasion of immune defences. A variety of structurally and functionally characterized adhesins and binding proteins of gram-positive bacteria facilitate these processes by specifically recognizing and interacting with various components of the host ECM, including different collagens, fibronectin and other macromolecules. The ECM affects the cellular physiology of our body and is critical for adhesion, migration, proliferation, and differentiation of many host cell types, but also provides the support for infiltrating pathogens, particularly under conditions of injury and trauma. Moreover, microbial binding to a variety of adhesive components in host tissue fluids leads to structural and/or functional alterations of host proteins and to the activation of cellular mechanisms that influence tissue and cell invasion of pathogens. Since the diverse interactions of gram-positive bacteria with the ECM represent important pathogenicity mechanisms, their characterization not only allows a better understanding of microbial invasion but also provides clues for the design of novel therapeutic strategies to manage infectious diseases.

Coagulation Pathways in Neurological Diseases: Multiple Sclerosis

Significant progress has been made in understanding the complex interactions between the coagulation system and inflammation and autoimmunity. Increased blood-brain-barrier (BBB) permeability, a key event in the pathophysiology of multiple sclerosis (MS), leads to the irruption into the central nervous system of blood components that include virtually all coagulation/hemostasis factors. Besides their cytotoxic deposition and role as a possible trigger of the coagulation cascade, hemostasis components cause inflammatory response and immune activation, sustaining neurodegenerative events in MS. Early studies showing the contribution of altered hemostasis in the complex pathophysiology of MS have been strengthened by recent studies using methodologies that permitted deeper investigation. Fibrin(ogen), an abundant protein in plasma, has been identified as a key contributor to neuroinflammation. Perturbed fibrinolysis was found to be a hallmark of progressive MS with abundant cortical fibrin(ogen) deposition. The immune-modulatory function of the intrinsic coagulation pathway still remains to be elucidated in MS. New molecular details in key hemostasis components participating in MS pathophysiology, and particularly involved in inflammatory and immune responses, could favor the development of novel therapeutic targets to ameliorate the evolution of MS. This review article introduces essential information on coagulation factors, inhibitors, and the fibrinolytic pathway, and highlights key aspects of their involvement in the immune system and inflammatory response. It discusses how hemostasis components are (dys)regulated in MS, and summarizes histopathological post-mortem human brain evidence, as well as cerebrospinal fluid, plasma, and serum studies of hemostasis and fibrinolytic pathways in MS. Studies of disease-modifying treatments as potential modifiers of coagulation factor levels, and case reports of autoimmunity affecting hemostasis in MS are also discussed.

Inflammatory biomarkers and subclinical carotid atherosclerosis in HIV-infected and HIV-uninfected men in the Multicenter AIDS Cohort Study

BACKGROUND

HIV-infected persons have an increased risk of atherosclerosis relative to uninfected individuals. Inflammatory processes may contribute to this risk. We evaluated the associations of 10 biomarkers of systemic inflammation (CRP, IL-6, sTNF-αR1 and 2), monocyte activation (CCL2, sCD163, sCD14), coagulation (fibrinogen, D-dimer), and endothelial dysfunction (ICAM-1) with subclinical carotid atherosclerosis among participants in the Multicenter AIDS Cohort Study (MACS).

METHODS

Carotid plaque and intima media thickness (IMT) in the common carotid (CCA-IMT) and bifurcation region were assessed by B mode ultrasound among 452 HIV-infected and 276 HIV-uninfected men from 2010-2013. Associations between levels of each biomarker and presence of focal plaque and IMT were assessed by logistic and linear regression models, adjusting for demographics, risk behaviors, traditional cardiovascular disease (CVD) risk factors, and HIV disease characteristics.

RESULTS

Compared to HIV-uninfected men, HIV-infected men had significantly higher levels of 8 of the 10 biomarkers. Overall, men with sCD163, CCL2, IL-6, and CRP levels in the highest quintile had approximately 2 times the odds of carotid plaque relative to those with levels in the lowest quintile, independent of demographic and CVD risk factors. Fibrinogen levels were positively associated with CCA-IMT while ICAM-1, CCL2, and sTNF-αR1 levels were positively associated with bifurcation-IMT. Among HIV-uninfected men, higher levels of sTNF-αR2 were positively associated with CCA-IMT, fibrinogen with bifurcation-IMT and carotid plaque, and ICAM-1 with carotid plaque.

CONCLUSION

In addition to greater levels of systemic inflammation, heightened monocyte activation (sCD163, CCL2) may contribute to the burden of atherosclerosis among HIV-infected persons.

How Adhesion Molecule Patterns Change While Neutrophils Traffic through the Lung during Inflammation

In acute pulmonary inflammation, polymorphonuclear cells (PMNs) pass a transendothelial barrier from the circulation into the lung interstitium followed by a transepithelial migration into the alveolar space. These migration steps are regulated differentially by a concept of adhesion molecules and remain-despite decades of research-incompletely understood. Current knowledge of changes in the expression pattern of adhesion molecules mainly derives from in vitro studies or from studies in extrapulmonary organ systems, where regulation of adhesion molecules differs significantly. In a murine model of lung inflammation, we determined the expression pattern of nine relevant neutrophilic adhesion molecules on their way through the different compartments of the lung. We used a flow cytometry-based technique that allowed describing spatial distribution of the adhesion molecules expressed on PMNs during their migration through the lung in detail. For example, the highest expression of CD29 was found in the intravascular compartment, highlighting its impact on the initial adhesion to the endothelium. CD47 showed its peak of expression on the later phase of transendothelial migration, whereas CD11b and CD54 expression peaked interstitial. A pivotal role for transepithelial migration was found for the adhesion molecule CD172a. Thereby, expression may correlate with functional impact for specific migration steps. In vitro studies further confirmed our in vivo findings. In conclusion, we are the first to determine the changes in expression patterns of relevant adhesion molecules on their migration through the different compartments of the lung. These findings may help to further understand the regulation of neutrophil trafficking in the lung.

The multifaceted role of fibrinogen in tissue injury and inflammation

The canonical role of the hemostatic and fibrinolytic systems is to maintain vascular integrity. Perturbations in either system can prompt primary pathological end points of hemorrhage or thrombosis with vessel occlusion. However, fibrin(ogen) and proteases controlling its deposition and clearance, including (pro)thrombin and plasmin(ogen), have powerful roles in driving acute and reparative inflammatory pathways that affect the spectrum of tissue injury, remodeling, and repair. Indeed, fibrin(ogen) deposits are a near-universal feature of tissue injury, regardless of the nature of the inciting event, including injuries driven by mechanical insult, infection, or immunological derangements. Fibrin can modify multiple aspects of inflammatory cell function by engaging leukocytes through a variety of cellular receptors and mechanisms. Studies on the role of coagulation system activation and fibrin(ogen) deposition in models of inflammatory disease and tissue injury have revealed points of commonality, as well as context-dependent contributions of coagulation and fibrinolytic factors. However, there remains a critical need to define the precise temporal and spatial mechanisms by which fibrinogen-directed inflammatory events may dictate the severity of tissue injury and coordinate the remodeling and repair events essential to restore normal organ function. Current research trends suggest that future studies will give way to the identification of novel hemostatic factor-targeted therapies for a range of tissue injuries and disease.

Identification of an intercellular cell adhesion molecule-1 homologue from grass carp: Evidence for its involvement in the immune cell adhesion in teleost

Intercellular cell adhesion molecule-1 (ICAM-1) is a single-chain transmembrane glycoprotein which plays key roles in transendothelial migration of leukocytes and interaction between antigen presenting cells and T cells. In teleost, information of cell adhesion-related molecules is still lacking. In this study, we identified a gene from grass carp sharing similar exon and intron organization with human ICAM-1. Cloning and in silico analysis of its homologues in zebrafish and other two cyprinid fishes, respectively demonstrated the existence of the gene in these fishes. Moreover, the molecular features of these genes in fishes were conserved compared with human ICAM-1. In grass carp, the transcripts of this gene were detected with high levels in heart and liver and its mRNA expression in headkidney leukocytes was induced by Il-1β. Overexpression of this molecule in COS-7 cells could increase the adhesion of the cells with grass carp peripheral blood lymphocytes (PBLs), and the adhesion was further enhanced by lipopolysaccharide stimulation on PBLs. Further studies revealed that the mRNA levels of lymphocyte function-associated antigen-1, a ligand for ICAM-1, were much higher in the PBLs adhering to the COS-7 cells with overexpressing this molecule than in the PBLs alone. These results collectively showed that the newly cloned cDNA encodes grass carp intercellular cell adhesion molecule-1 (Icam-1) and it can mediate the adhesion of PBLs. This provides functional evidence for the existence of Icam-1 in teleost and will facilitate investigation on the transendothelial migration of leukocytes in fish species.

Hyperfibrinogenemia-mediated astrocyte activation

Fibrinogen (Fg)-containing plaques are associated with memory loss during various inflammatory neurodegenerative diseases such as Alzheimer's disease, multiple sclerosis, stroke, and traumatic brain injury. However, mechanisms of its action in neurovascular unit are not clear. As Fg is a high molecular weight blood protein and cannot translocate far from the vessel after extravasation, we hypothesized that it may interact with astrocytes first causing their activation. Cultured mouse cortical astrocytes were treated with Fg in the presence or absence of function-blocking anti-mouse intercellular adhesion molecule 1 (ICAM-1) antibody, or with medium alone (control). Expressions of ICAM-1 and tyrosine receptor kinase B (TrkB) as markers of astrocyte activation, and phosphorylation of TrkB (pTrkB) were assessed. Fg dose-dependently increased activation of astrocytes defined by their shape change, retraction of processes, and enhanced expressions of ICAM-1 and TrkB, and increased pTrkB. Blocking of ICAM-1 function ameliorated these Fg effects. Data suggest that Fg interacts with astrocytes causing overexpression of ICAM-1 and TrkB, and TrkB phosphorylation, and thus, astrocyte activation. Since TrkB is known to be involved in neurodegeneration, interaction of Fg with astrocytes and the resultant activation of TrkB can be a possible mechanism involved in memory reduction, which were observed in previous studies and were associated with formation of complexes of Fg deposited in extravascular space with proteins such as Amyloid beta or prion, the proteins involved in development of dementia.

Prognostic value of combined preoperative fibrinogen and neutrophil-lymphocyte ratio in patients with hepatocellular carcinoma after liver transplantation

OBJECTIVES

Elevated plasma fibrinogen (Fib) correlated with patient's prognosis in several solid tumors. However, few studies have illuminated the relationship between preoperative Fib and prognosis of HCC after liver transplantation. We aimed to clarify the prognostic value of Fib and whether the prognostic accuracy can be enhanced by the combination of Fib and neutrophil-lymphocyte ratio (NLR).

RESULTS

Fib was correlated with Child-pugh stage, alpha-fetoprotein (AFP), size of largest tumor, macro- and micro-vascular invasion. Univariate analysis showed preoperative Fib, AFP, NLR, size of largest tumor, tumor number, macro- and micro- vascular invasion were significantly associated with disease-free survival (DFS) and overall survival (OS) in HCC patients with liver transplantation. After multivariate analysis, only Fib and macro-vascular invasion were independently correlated with DFS and OS. Survival analysis showed that preoperative Fib > 2.345 g/L predicted poor prognosis of patients HCC after liver transplantation. Preoperative Fib showed prognostic value in various subgroups of HCC. Furthermore, the predictive range was expanded by the combination of Fib and NLR.

MATERIALS AND METHODS

Data were collected retrospectively from 130 HCC patients who underwent liver transplantation. Preoperative Fib, NLR and clinicopathologic variables were analyzed. The survival analysis was performed by the Kaplan-Meier method, and compared by the log-rank test. Univariate and multivariate analyses were performed to identify the prognostic factors for DFS and OS.

CONCLUSIONS

Preoperative Fib is an independent effective predictor of prognosis for HCC patients, higher levels of Fib predict poorer outcomes and the combination of Fib and NLR enlarges the prognostic accuracy of testing.

Effect of fibrinogen, fibrin, and fibrin degradation products on transendothelial migration of leukocytes

In spite of numerous studies on the involvement of fibrinogen in transendothelial migration of leukocytes and thereby inflammation, there is still no clear understanding of which fibrin(ogen) species can stimulate leukocyte transmigration. Although we have previously proposed that interaction of fibrin with the VLDL receptor (VLDLR) promotes leukocyte transmigration, there is no direct experimental evidence for the involvement of fibrin in this process. To address these questions, we performed systematic studies of interaction of VLDLR with fibrinogen, fibrin, and their isolated recombinant BβN- and βN-domains, respectively, and the effect of various fibrin(ogen) species on transendothelial migration of leukocytes. The results obtained revealed that freshly purified fibrinogen does not interact with VLDLR in solution and has practically no effect on leukocyte transmigration. They also indicate that the VLDLR-binding site is cryptic in fibrinogen and becomes accessible upon its adsorption onto a surface or upon its conversion into fibrin. We also found that the D-D:E₁ complex and higher molecular mass fibrin degradation products, as well as soluble fibrin and fibrin polymers (clots) anchored to the endothelial monolayer, promote leukocyte transmigration mainly through the VLDL receptor-dependent pathway. Thus, the results of the present study suggest that fibrin degradation products and soluble fibrin that may be present in the circulation in vivo, as well as fibrin clots that may be deposited on the surface of inflamed endothelium, promote leukocyte transmigration. These findings further clarify the molecular mechanisms underlying the fibrin-VLDLR-dependent pathway of leukocyte transmigration and provide an explanation for a possible (patho)physiological role of this pathway.

Retrospective Proteomic Analysis of a Novel, Cancer Metastasis-Promoting RGD-Containing Peptide

Patients who undergo surgical extirpation of a primary liver carcinoma followed by radiotherapy and chemotherapy leading to complete remission are nevertheless known to develop cancerous metastases 3-10 years later. We retrospectively examined the blood sera collected over 8 years from 30 patients who developed bone metastases after the complete remission of liver cancer to identify serum proteins showing differential expression compared to patients without remission. We detected a novel RGD (Arg-Gly-Asp)-containing peptide derived from the C-terminal portion of fibrinogen in the sera of metastatic patients that appeared to control the EMT (epithelial-mesenchymal transition) of cancer cells, in a process associated with miR-199a-3p. The RGD peptide enhanced new blood vessel growth and increased vascular endothelial growth factor levels when introduced into fertilized chicken eggs. The purpose of this study was to enable early detection of metastatic cancer cells using the novel RGD peptide as a biomarker, and thereby develop new drugs for the treatment of metastatic cancer.

Usefulness of Preoperative Plasma Fibrinogen Versus Other Prognostic Markers for Predicting Gastric Cancer Recurrence

BACKGROUND

Hypercoagulation is associated with tumor progression and metastasis in various types of malignancy. We compared the prognostic value of preoperative plasma fibrinogen level with those of other prognostic markers in patients with gastric cancer and assessed whether fibrinogen level was an independent prognostic indicator.

METHODS

We collected preoperative data from 609 consecutive patients with gastric cancer who underwent curative gastrectomy. A receiver operating curve (ROC) was used to compare the sensitivity and specificity of carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), C-reactive protein (CRP), platelet count, platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and fibrinogen level in predicting recurrence. Recurrence-free survival (RFS) and overall survival (OS) were compared between the normal and high fibrinogen groups.

RESULTS

In the ROC analysis, the area under the curve (AUC) was 0.534 for CEA, 0.552 for CA19-9, 0.587 for CRP, 0.565 for platelet count, 0.567 for PLR, 0.522 for NLR, and 0.692 for fibrinogen. Plasma fibrinogen level increased with tumor stage. The high fibrinogen (≥350 mg/dl) group had significantly worse RFS (p < 0.001) and OS (p < 0.001) than the normal fibrinogen (<350 mg/dl) group. Cox multivariate analysis of RFS revealed that fibrinogen level was an independent prognostic factor (p < 0.001) in addition to sex, pT stage, and pN stage.

CONCLUSIONS

Preoperative plasma fibrinogen level had the highest predictive value for recurrence among seven known prognostic markers. Since fibrinogen level is an independent factor for RFS, it would be useful for predicting prognosis after gastric cancer surgery.