Heparin Displaces Interferon-γ–Inducible Chemokines (IP-10, I-TAC, and Mig) Sequestered in the Vasculature and Inhibits the Transendothelial Migration and Arterial Recruitment of T Cells

Effect of tocilizumab on endothelial and platelet-derived CXC-chemokines and their association with inflammation and myocardial injury in STEMI patients undergoing primary PCI

BACKGROUND

Tocilizumab improves myocardial salvage in ST-elevation myocardial infarction (STEMI) patients when administered before percutaneous coronary intervention (PCI). The mechanisms underlying ischemia-reperfusion injury remain unclear. In this sub-study, we investigated whether endothelial and platelet-derived CXC chemokines are involved, as they represent inflammatory mediators from two cell types relevant to myocardial infarction. Associations between these chemokines and neutrophils, C-reactive protein (CRP), troponin T (TnT), myocardial salvage index (MSI), microvascular obstruction (MVO), and infarct size.

METHODS

This is a sub-study of the ASSAIL-MI trial, a double-blind clinical trial that randomized 199 STEMI patients to receive either 280 mg tocilizumab (n = 101) or placebo (n = 98) intravenously before PCI. Blood samples were collected prior to infusion, at day 1-2, 3-7, and at 3 and 6 months. Heparin was administered before baseline in 150 patients, while 49 received it after. We measured CXC-chemokines CXCL4, CXCL5, CXCL6, CXCL7, and CXCL12 using immunoassays. Cardiac MRI was performed in the first week and at 6 months.

RESULTS

Tocilizumab did not significantly affect CXC-chemokines levels. Although some correlations were observed between chemokine levels and neutrophil counts and CRP, none of the CXC chemokines were associated with infarct size, MSI, MVO, or TnT levels. Notably, CXCL 12 levels increased in patients who received heparin before baseline, while other CXC-chemokines decreased significantly.

CONCLUSION

This study suggests that the beneficial effects of tocilizumab in STEMI patients are not due to changes in circulating endothelial or platelet-derived CXC-chemokines, compared to placebo. However, heparin significantly influences the levels of these chemokines.

Natural carboxyterminal truncation of human CXCL10 attenuates glycosaminoglycan binding, CXCR3A signaling and lymphocyte chemotaxis, while retaining angiostatic activity

BACKGROUND

Interferon-γ-inducible protein of 10 kDa (IP-10/CXCL10) is a dual-function CXC chemokine that coordinates chemotaxis of activated T cells and natural killer (NK) cells via interaction with its G protein-coupled receptor (GPCR), CXC chemokine receptor 3 (CXCR3). As a consequence of natural posttranslational modifications, human CXCL10 exhibits a high degree of structural and functional heterogeneity. However, the biological effect of natural posttranslational processing of CXCL10 at the carboxy (C)-terminus has remained partially elusive. We studied CXCL10(1-73), lacking the four endmost C-terminal amino acids, which was previously identified in supernatant of cultured human fibroblasts and keratinocytes.

METHODS

Relative levels of CXCL10(1-73) and intact CXCL10(1-77) were determined in synovial fluids of patients with rheumatoid arthritis (RA) through tandem mass spectrometry. The production of CXCL10(1-73) was optimized through Fmoc-based solid phase peptide synthesis (SPPS) and a strategy to efficiently generate human CXCL10 proteoforms was introduced. CXCL10(1-73) was compared to intact CXCL10(1-77) using surface plasmon resonance for glycosaminoglycan (GAG) binding affinity, assays for cell migration, second messenger signaling downstream of CXCR3, and flow cytometry of CHO cells and primary human T lymphocytes and endothelial cells. Leukocyte recruitment in vivo upon intraperitoneal injection of CXCL10(1-73) was also evaluated.

RESULTS

Natural CXCL10(1-73) was more abundantly present compared to intact CXCL10(1-77) in synovial fluids of patients with RA. CXCL10(1-73) had diminished affinity for GAG including heparin, heparan sulfate and chondroitin sulfate A. Moreover, CXCL10(1-73) exhibited an attenuated capacity to induce CXCR3A-mediated signaling, as evidenced in calcium mobilization assays and through quantification of phosphorylated extracellular signal-regulated kinase-1/2 (ERK1/2) and protein kinase B/Akt. Furthermore, CXCL10(1-73) incited significantly less primary human T lymphocyte chemotaxis in vitro and peritoneal ingress of CXCR3+ T lymphocytes in mice. In contrast, loss of the four endmost C-terminal residues did not affect the inhibitory properties of CXCL10 on migration, proliferation, wound closure, phosphorylation of ERK1/2, and sprouting of human microvascular endothelial cells.

CONCLUSION

Our study shows that the C-terminal residues Lys74-Pro77 of CXCL10 are important for GAG binding, signaling through CXCR3A, T lymphocyte chemotaxis, but dispensable for angiostasis.

A review of the pleiotropic actions of the IFN-inducible CXC chemokine receptor 3 ligands in the synovial microenvironment

Chemokines are pivotal players in instigation and perpetuation of synovitis through leukocytes egress from the blood circulation into the inflamed articulation. Multitudinous literature addressing the involvement of the dual-function interferon (IFN)-inducible chemokines CXCL9, CXCL10 and CXCL11 in diseases characterized by chronic inflammatory arthritis emphasizes the need for detangling their etiopathological relevance. Through interaction with their mutual receptor CXC chemokine receptor 3 (CXCR3), the chemokines CXCL9, CXCL10 and CXCL11 exert their hallmark function of coordinating directional trafficking of CD4+ TH1 cells, CD8+ T cells, NK cells and NKT cells towards inflammatory niches. Among other (patho)physiological processes including infection, cancer, and angiostasis, IFN-inducible CXCR3 ligands have been implicated in autoinflammatory and autoimmune diseases. This review presents a comprehensive overview of the abundant presence of IFN-induced CXCR3 ligands in bodily fluids of patients with inflammatory arthritis, the outcomes of their selective depletion in rodent models, and the attempts at developing candidate drugs targeting the CXCR3 chemokine system. We further propose that the involvement of the CXCR3 binding chemokines in synovitis and joint remodeling encompasses more than solely the directional ingress of CXCR3-expressing leukocytes. The pleotropic actions of the IFN-inducible CXCR3 ligands in the synovial niche reiteratively illustrate the extensive complexity of the CXCR3 chemokine network, which is based on the intercommunion of IFN-inducible CXCR3 ligands with distinct CXCR3 isoforms, enzymes, cytokines, and infiltrated and resident cells present in the inflamed joints.

Continuous Infusion Low-Dose Unfractionated Heparin for the Management of Hypercoagulability Associated With COVID-19

INTRODUCTION

The Coronavirus Disease 2019 (COVID-19) is associated with severe hypercoagulability. There is currently limited evidence supporting the routine use of therapeutic anticoagulation in the setting of COVID-19.

OBJECTIVES

The primary objective was to compare the incidence of thromboembolic events in adult patients with COVID-19 treated with an unfractionated heparin (UFH) infusion versus prophylactic dose anticoagulation. Secondary objectives included exploration of the efficacy and safety of an UFH infusion through the evaluation of organ function and incidence of minor and major bleeding.

METHODS

Retrospective observational cohort study with propensity score matching of COVID-19 patients who received an UFH infusion targeting an aPTT between 40 and 60 seconds.

RESULTS

Fifty-six patients were included in this study. There was no difference in the composite of thromboembolic events comprised of venous thromboembolism, arterial thrombosis, and catheter-related thrombosis between the UFH and control group (17.9% vs. 3.6%, P = 0.19). There was a significant increase in median D-dimer concentrations from day 1 to day 7 in the control group (475 ng/mL [291-999] vs. 10820 ng/mL [606-21033], P = 0.04). Patients treated with UFH had a higher incidence of minor bleeding (35.7% vs. 0%, P < 0.005) and required more units of packed red blood cell transfusion (0.8 units ± 1.6 vs. 0 units, P = 0.01).

CONCLUSION

Continuous infusion of UFH for patients with COVID-19 infection did not decrease the overall incidence of thromboembolic complications. UFH was associated with stabilization of D-dimer concentrations and increased rates of minor bleeding and transfusions.

Prevention of the post thrombotic syndrome with anticoagulation: a narrative review

The post thrombotic syndrome (PTS) is chronic venous insufficiency secondary to a prior deep vein thrombosis (DVT). It is the most common complication of VTE and, while not fatal, it can lead to chronic, unremitting symptoms as well as societal and economic consequences. The cornerstone of PTS treatment lies in its prevention after DVT. Specific PTS preventative measures include the use of elastic compression stockings (ECS) and pharmacomechanical catheter directed thrombolysis (PCDT). However, the efficacy of these treatments has been questioned by large RCTs. So far, anticoagulation, primarily prescribed to prevent DVT extension and recurrence, appears to be the only unquestionably effective treatment for the prevention of PTS. In this literature review we present pathophysiological, biological, radiological and clinical data supporting the efficacy of anticoagulants to prevent PTS and the possible differential efficacy among available classes of anticoagulants (vitamin K antagonists (VKA), low molecular weight heparins (LMWHs) and direct oral anticoagulants (DOACs)). Data suggest that LMWHs and DOACs are superior to VKAs, but no head-to-head comparison is available between DOACs and LMWHs. Owing to their potentially greater anti-inflammatory properties, LMWHs could be superior to DOACs. This finding may be of interest particularly in patients with extensive DVT at high risk of moderate to severe PTS, but needs to be confirmed by a dedicated RCT.

The Involvement of CXC Motif Chemokine Ligand 10 (CXCL10) and Its Related Chemokines in the Pathogenesis of Coronary Artery Disease and in the COVID-19 Vaccination: A Narrative Review

Coronary artery disease (CAD) and coronary heart disease (CHD) constitute two of the leading causes of death in Europe, USA and the rest of the world. According to the latest reports of the Iranian National Health Ministry, CAD is the main cause of death in Iranian patients with an age over 35 years despite a significant reduction in mortality due to early interventional treatments in the context of an acute coronary syndrome (ACS). Inflammation plays a fundamental role in coronary atherogenesis, atherosclerotic plaque formation, acute coronary thrombosis and CAD establishment. Chemokines are well-recognized mediators of inflammation involved in several bio-functions such as leucocyte migration in response to inflammatory signals and oxidative vascular injury. Different chemokines serve as chemo-attractants for a wide variety of cell types including immune cells. CXC motif chemokine ligand 10 (CXCL10), also known as interferon gamma-induced protein 10 (IP-10/CXLC10), is a chemokine with inflammatory features whereas CXC chemokine receptor 3 (CXCR3) serves as a shared receptor for CXCL9, 10 and 11. These chemokines mediate immune responses through the activation and recruitment of leukocytes, eosinophils, monocytes and natural killer (NK) cells. CXCL10, interleukin (IL-15) and interferon (IFN-g) are increased after a COVID-19 vaccination with a BNT162b2 mRNA (Pfizer/BioNTech) vaccine and are enriched by tumor necrosis factor alpha (TNF-α) and IL-6 after the second vaccination. The aim of the present study is the presentation of the elucidation of the crucial role of CXCL10 in the patho-physiology and pathogenesis of CAD and in identifying markers associated with the vaccination resulting in antibody development.

Targeting Chemokine-Glycosaminoglycan Interactions to Inhibit Inflammation

Leukocyte migration into tissues depends on the activity of chemokines that form concentration gradients to guide leukocytes to a specific site. Interaction of chemokines with their specific G protein-coupled receptors (GPCRs) on leukocytes induces leukocyte adhesion to the endothelial cells, followed by extravasation of the leukocytes and subsequent directed migration along the chemotactic gradient. Interaction of chemokines with glycosaminoglycans (GAGs) is crucial for extravasation in vivo. Chemokines need to interact with GAGs on endothelial cells and in the extracellular matrix in tissues in order to be presented on the endothelium of blood vessels and to create a concentration gradient. Local chemokine retention establishes a chemokine gradient and prevents diffusion and degradation. During the last two decades, research aiming at reducing chemokine activity mainly focused on the identification of inhibitors of the interaction between chemokines and their cognate GPCRs. This approach only resulted in limited success. However, an alternative strategy, targeting chemokine-GAG interactions, may be a promising approach to inhibit chemokine activity and inflammation. On this line, proteins derived from viruses and parasites that bind chemokines or GAGs may have the potential to interfere with chemokine-GAG interactions. Alternatively, chemokine mimetics, including truncated chemokines and mutant chemokines, can compete with chemokines for binding to GAGs. Such truncated or mutated chemokines are characterized by a strong binding affinity for GAGs and abrogated binding to their chemokine receptors. Finally, Spiegelmers that mask the GAG-binding site on chemokines, thereby preventing chemokine-GAG interactions, were developed. In this review, the importance of GAGs for chemokine activity in vivo and strategies that could be employed to target chemokine-GAG interactions will be discussed in the context of inflammation.

Potential Effects of CXCL9 and CCL20 on Cardiac Fibrosis in Patients with Myocardial Infarction and Isoproterenol-Treated Rats

The chemokines CXCL9 and CCL20 have been reported to be associated with ventricular dysfunction. This study was aimed to investigate the effects of CXCL9/CCL20 on cardiac fibrosis following myocardial infarction (MI). Blood samples of patients with MI were obtained to determine the serum CXCL9, CCL20, tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β). The expression of CXCL9 and CCL20 in hypoxia-incubated H9c2 cells and TNF-α/TGF-β-activated peripheral blood mononuclear cells (PBMCs) were examined. The experimental MI of rats was produced by the intraperitoneal injection of isoproterenol (ISO) (85 mg/kg/day) for two consecutive days. The growth and migration of CXCL9/CCL20-incubated cardiac fibroblasts in vitro were evaluated. TNF-α/TGF-β-activated PBMCs showed an enhanced expression of CXCL9 and CCL20, while hypoxic H9c2 cells did not. Patients with MI had significantly enhanced levels of serum TGF-β and CXCL9 compared to healthy subjects. ISO-treated rats had increased serum CXCL9 levels and marked cardiac fibrosis compared to control rats. The trend of increased serum CCL20 in patients with MI and ISO-treated rats was not significant. CXCL9-incubated cardiac fibroblasts showed enhanced proliferation and migration. The findings of this study suggest that an enhanced expression of CXCL9 following MI might play a role in post-MI cardiac fibrosis by activating cardiac fibroblasts.

Support of Tumor Endothelial Cells by Chemokine Receptors

Tumor-associated vascular endothelium comprises a specialized and diverse group of endothelial cells that, although not cancer themselves, are integral to cancer progression. Targeting the tumor vasculature can have significant efficacy in reducing tumor burden, although loss of efficacy due to acquisition of resistance mechanisms is common. Here we review mechanisms by which tumor endothelial cells (TEC) utilize chemokine receptors to support tumor progression. We illustrate how chemokine receptors support and may serve as functional markers of the diverse TEC population. We focus on ACKR1 (DARC), ACKR3 (CXCR7), CXCR4, and CCR2, as these are the best studied chemokine receptors in TEC; and suggest that targeting these receptors on the tumor vasculature may prove efficacious in slowing or reversing tumor growth. We also mention CXCR2 and CXCR3 as important mediators or tumor angiogenesis, given their distinct roles with angiogenic and angiostatic chemokines, respectively.

AIP1 Suppresses Transplant Arteriosclerosis Through Inhibition of Vascular Smooth Muscle Cell Inflammatory Response to IFNγ

IFNγ-induced vascular smooth muscle cells (VSMCs) inflammatory response plays a key role in transplant arteriosclerosis (TA). However, the mechanisms regulating this process remains poorly defined. Here, we show that ASK1-interacting protein 1 (AIP1) deletion markedly augments the expression of IFNγ-induced chemokines in mouse aortic allografts. Subsequently, donor arterial grafts from AIP1 deficient mice exhibited an accelerated development of TA. Furthermore, AIP1 knockdown significantly increased IFNγ signaling activation in cultured VSMCs and thus enhances chemokines production in response to IFNγ. Together, we conclude that AIP1 functions as an inhibitor of VSMCs inflammation by regulating IFNγ signaling and therefore suppresses TA progression. Our findings suggest that AIP1 might be a potential therapeutic target for chronic transplant rejection. Anat Rec, 302:1587-1593, 2019. © 2018 American Association for Anatomy.

The Role of CXCR3 and Associated Chemokines in the Development of Atherosclerosis and During Myocardial Infarction

The chemokine receptor CXCR3 and associated CXC chemokines have been extensively investigated in several inflammatory and autoimmune diseases as well as in tumor development. Recent studies have indicated the role of these chemokines also in cardiovascular diseases. We aimed to present current knowledge regarding the role of CXCR3-binding chemokines in the pathogenesis of atherosclerosis and during acute myocardial infarction.

Overview of the Mechanisms that May Contribute to the Non-Redundant Activities of Interferon-Inducible CXC Chemokine Receptor 3 Ligands

The inflammatory chemokines CXCL9, CXCL10, and CXCL11 are predominantly induced by interferon (IFN)-γ and share an exclusive chemokine receptor named CXC chemokine receptor 3 (CXCR3). With a prototype function of directing temporal and spatial migration of activated T cells and natural killer cells, and inhibitory effects on angiogenesis, these CXCR3 ligands have been implicated in infection, acute inflammation, autoinflammation and autoimmunity, as well as in cancer. Intense former research efforts led to recent and ongoing clinical trials using CXCR3 and CXCR3 ligand targeting molecules. Scientific evidence has claimed mutual redundancy, ligand dominance, collaboration or even antagonism, depending on the (patho)physiological context. Most research on their in vivo activity, however, illustrates that CXCL9, CXCL10, and CXCL11 each contribute to the activation and trafficking of CXCR3 expressing cells in a non-redundant manner. When looking into detail, one can unravel a multistep machinery behind final CXCR3 ligand functions. Not only can specific cell types secrete individual CXCR3 interacting chemokines in response to certain stimuli, but also the receptor and glycosaminoglycan interactions, major associated intracellular pathways and susceptibility to processing by particular enzymes, among others, seem ligand-specific. Here, we overview major aspects of the molecular properties and regulatory mechanisms of IFN-induced CXCR3 ligands, and propose that their in vivo non-redundancy is a reflection of the unprecedented degree of versatility that seems inherent to the IFN-related CXCR3 chemokine system.

Trombo flutuante em veia femoral

O trombo venoso flutuante em veia femoral é um tipo de trombo com alto potencial de embolização pulmonar. Entretanto, ainda é controversa a conduta mais apropriada nesses casos. Tratamentos clínicos com anticoagulantes ou fibrinolíticos e trombectomias abertas ou por meio de dispositivos endovasculares vêm sendo empregados ainda sem um critério de indicação bem definido. Apresentamos três casos clínicos de trombos flutuantes em veia femoral, de etiologias distintas, cujos tratamentos e respectivas evoluções serão discutidos.

Retinal vein thrombosis: The Internist's role in the etiologic and therapeutic management

Retinal vein occlusion is a common and important cause of vision loss. In general, knowledge about this condition is scant within an internist's practice but the condition is relevant because of its association with other chronic ailments. A diagnosis of RVO should prompt the investigation of conditions needing chronic management in these patients. In this review we summarize the clinical presentation of RVO, its classification, associated risk factors, and treatment focused in the internist's scope of practice.

Relationship of Genetic Polymorphisms of the Chemokine, CCL5, and Its Receptor, CCR5, with Coronary Artery Disease in Taiwan

The chemokine receptor CCR5 polymorphism, which confers resistance to HIV infection, has been associated with reduced risk of cardiovascular disease. However, the association of the chemokine, CCL5, and its receptor, CCR5, polymorphism and coronary artery disease (CAD) in the Taiwanese has not been studied. In this study, 483 subjects who received elective coronary angiography were recruited from Chung Shan Medical University Hospital. CCL5-403 and CCR5-59029 were determined by polymerase chain reaction-restriction fragment length polymorphism. We found that CCL5-403 with TT genotype frequencies was significantly associated with the risk of CAD group (odds ratio = 3.063 and p = 0.012). Moreover, the frequencies of CCR5-59029 with GG or GA genotype were higher than AA genotype in acute coronary syndrome individuals (odds ratio = 1.853, CI = 1.176–2.921, p = 0.008). In conclusion, we found that CCL5-403 polymorphism may increase genetic susceptibility of CAD. CCL5-403 or CCR5-59029 single nucleotide polymorphism may include genotype score and it may predict cardiovascular event.

Role of the endothelial surface layer in neutrophil recruitment

Neutrophil recruitment in most tissues is limited to postcapillary venules, where E- and P-selectins are inducibly expressed by venular endothelial cells. These molecules support neutrophil rolling via binding of PSGL-1 and other ligands on neutrophils. Selectins extend ≤ 38 nm above the endothelial plasma membrane, and PSGL-1 extends to 50 nm above the neutrophil plasma membrane. However, endothelial cells are covered with an ESL composed of glycosaminoglycans that is ≥ 500 nm thick and has measurable resistance against compression. The neutrophil surface is also covered with a surface layer. These surface layers would be expected to completely shield adhesion molecules; thus, neutrophils should not be able to roll and adhere. However, in the cremaster muscle and in many other models investigated using intravital microscopy, neutrophils clearly roll, and their rolling is easily and quickly induced. This conundrum was thought to be resolved by the observation that the induction of selectins is accompanied by ESL shedding; however, ESL shedding only partially reduces the ESL thickness (to 200 nm) and thus is insufficient to expose adhesion molecules. In addition to its antiadhesive functions, the ESL also presents neutrophil arrest-inducing chemokines. ESL heparan sulfate can also bind L-selectin expressed by the neutrophils, which contributes to rolling and arrest. We conclude that ESL has both proadhesive and antiadhesive functions. However, most previous studies considered either only the proadhesive or only the antiadhesive effects of the ESL. An integrated model for the role of the ESL in neutrophil rolling, arrest, and transmigration is needed.

Pig-to-baboon heterotopic heart transplantation--exploratory preliminary experience with pigs transgenic for human thrombomodulin and comparison of three costimulation blockade-based regimens

BACKGROUND

Three costimulation blockade-based regimens have been explored after transplantation of hearts from pigs of varying genetic backgrounds to determine whether CTLA4-Ig (abatacept) or anti-CD40mAb+CTLA4-Ig (belatacept) can successfully replace anti-CD154mAb.

METHODS

All pigs were on an α1,3-galactosyltransferase gene-knockout/CD46 transgenic (GTKO.CD46) background. Hearts transplanted into Group A baboons (n=4) expressed additional CD55, and those into Group B (n=3) expressed human thrombomodulin (TBM). Immunosuppression included anti-thymocyte globulin with anti-CD154mAb (Regimen 1: n=2) or abatacept (Regimen 2: n=2) or anti-CD40mAb+belatacept (Regimen 3: n=2). Regimens 1 and 2 included induction anti-CD20mAb and continuous heparin. One further baboon in Group B (B16311) received a modified Regimen 1. Baboons were followed by clinical/laboratory monitoring of immune/coagulation parameters. At biopsy, graft failure, or euthanasia, the graft was examined by microscopy.

RESULTS

Group A baboons survived 15 to 33 days, whereas Group B survived 52, 99, and 130 days, respectively. Thrombocytopenia and reduction in fibrinogen occurred within 21 days in Group A, suggesting thrombotic microangiopathy (TM), confirmed by histopathology. In Group B, with follow-up for >4 m, areas of myofiber degeneration and scarring were seen in two hearts at necropsy. A T-cell response was documented only in baboons receiving Regimen 2.

CONCLUSIONS

The combination of anti-CD40mAb+belatacept proved effective in preventing a T-cell response. The expression of TBM prevented thrombocytopenia and may possibly delay the development of TM and/or consumptive coagulopathy.

Heparin/Heparan sulfate proteoglycans glycomic interactome in angiogenesis: biological implications and therapeutical use

Angiogenesis, the process of formation of new blood vessel from pre-existing ones, is involved in various intertwined pathological processes including virus infection, inflammation and oncogenesis, making it a promising target for the development of novel strategies for various interventions. To induce angiogenesis, angiogenic growth factors (AGFs) must interact with pro-angiogenic receptors to induce proliferation, protease production and migration of endothelial cells (ECs). The action of AGFs is counteracted by antiangiogenic modulators whose main mechanism of action is to bind (thus sequestering or masking) AGFs or their receptors. Many sugars, either free or associated to proteins, are involved in these interactions, thus exerting a tight regulation of the neovascularization process. Heparin and heparan sulfate proteoglycans undoubtedly play a pivotal role in this context since they bind to almost all the known AGFs, to several pro-angiogenic receptors and even to angiogenic inhibitors, originating an intricate network of interaction, the so called "angiogenesis glycomic interactome". The decoding of the angiogenesis glycomic interactome, achievable by a systematic study of the interactions occurring among angiogenic modulators and sugars, may help to design novel antiangiogenic therapies with implications in the cure of angiogenesis-dependent diseases.

Inflammatory and immune responses in the arterial media

Inflammatory arterial diseases differentially affect the compartments of the vessel wall. The intima and adventitia are commonly involved by the disease process, with luminal and microvascular endothelial cells playing a critical role in the recruitment and activation of leukocytes. In contrast, the avascular media is often spared by immune-mediated disorders. Surprisingly, vascular smooth muscle cells (VSMCs), the predominant and often exclusive cell type of the media, are capable of robust proinflammatory responses to diverse stressors. The multiple cytokines and chemokines produced within the media can profoundly affect macrophage and T cell function, thus amplifying and shaping innate and adaptive immune responses. On the other hand, VSMCs and the extracellular matrix that they produce also display significant anti-inflammatory properties. The balance between the pro- and anti-inflammatory effects of VSMCs and their extracellular matrix versus the strength of the inciting immunologic events determines the pattern of medial pathology. Limitations on the extent of medial infiltration and injury, defined as medial immunoprivilege, are typically seen in arteriosclerotic diseases, such as atherosclerosis and transplant vasculopathy. Conversely, breakdown of medial immunoprivilege that manifests as more intense leukocytic infiltrates, loss of VSMCs, and destruction of the extracellular matrix architecture is a general feature of certain aneurysmal diseases and vasculitides. In this review, we consider the inflammatory and immune functions of VSMCs and how they may lead to medial immunoprivilege or medial inflammation in arterial diseases.

Heparan sulfate-dependent enhancement of henipavirus infection

Nipah virus and Hendra virus are emerging, highly pathogenic, zoonotic paramyxoviruses that belong to the genus Henipavirus. They infect humans as well as numerous mammalian species. Both viruses use ephrin-B2 and -B3 as cell entry receptors, and following initial entry into an organism, they are capable of rapid spread throughout the host. We have previously reported that Nipah virus can use another attachment receptor, different from its entry receptors, to bind to nonpermissive circulating leukocytes, thereby promoting viral dissemination within the host. Here, this attachment molecule was identified as heparan sulfate for both Nipah virus and Hendra virus. Cells devoid of heparan sulfate were not able to mediate henipavirus trans-infection and showed reduced permissivity to infection. Virus pseudotyped with Nipah virus glycoproteins bound heparan sulfate and heparin but no other glycosaminoglycans in a surface plasmon resonance assay. Furthermore, heparin was able to inhibit the interaction of the viruses with the heparan sulfate and to block cell-mediated trans-infection of henipaviruses. Moreover, heparin was shown to bind to ephrin-B3 and to restrain infection of permissive cells in vitro. Consequently, treatment with heparin devoid of anticoagulant activity improved the survival of Nipah virus-infected hamsters. Altogether, these results reveal heparan sulfate as a new attachment receptor for henipaviruses and as a potential therapeutic target for the development of novel approaches against these highly lethal infections.

IMPORTANCE

The Henipavirus genus includes two closely related, highly pathogenic paramyxoviruses, Nipah virus and Hendra virus, which cause elevated morbidity and mortality in animals and humans. Pathogenesis of both Nipah virus and Hendra virus infection is poorly understood, and efficient antiviral treatment is still missing. Here, we identified heparan sulfate as a novel attachment receptor used by both viruses to bind host cells. We demonstrate that heparin was able to inhibit the interaction of the viruses with heparan sulfate and to block cell-mediated trans-infection of henipaviruses. Moreover, heparin also bound to the viral entry receptor and thereby restricted infection of permissive cells in vitro. Consequently, heparin treatment improved survival of Nipah virus-infected hamsters. These results uncover an important role of heparan sulfate in henipavirus infection and open novel perspectives for the development of heparan sulfate-targeting therapeutic approaches for these emerging infections.

TRIF-dependent innate immune activation is critical for survival to neonatal gram-negative sepsis

Current evidence suggests that neonatal immunity is functionally distinct from adults. Although TLR signaling through the adaptor protein, MyD88, has been shown to be critical for survival to sepsis in adults, little is known about the role of MyD88 or TRIF in neonatal sepsis. We demonstrate that TRIF(-/-) but not MyD88(-/-) neonates are highly susceptible to Escherichia coli peritonitis and bacteremia. This was associated with decreased innate immune recruitment and function. Importantly, we found that the reverse was true in adults that MyD88(-/-) but not TRIF(-/-) or wild-type adults are susceptible to E. coli peritonitis and bacteremia. In addition, we demonstrate that TRIF but not MyD88 signaling is critical for the TLR4 protective adjuvant effect we have previously demonstrated. These data suggest a differential requirement for the survival of neonates versus adults to Gram-negative infection, and that modulation of TRIF in neonates can be used to augment survival to neonatal sepsis.

Serum levels of CXCR3 ligands predict T cell-mediated acute rejection after kidney transplantation

The early diagnosis of acute rejection is crucial for graft survival after kidney transplantation. The interferon-γ (IFNγ)-CXCR3-chemokine-dependent inflammatory loop plays a pivotal role in the recruitment of T lymphocytes during acute rejection. Previously published studies have typically focused on the CXCR3 receptor rather than on its ligands. In the present study, we used Luminex assays to detect the levels of CXCR3 ligands, monokine induced by IFNγ (MIG), IFN-induced protein 10 (IP-10) and IFN-induced T‑cell chemoattractant (I-TAC), in the serum of renal allograft recipients. According to a renal biopsy performed one month after kidney transplantation, 32 recipients were diagnosed with T cell-mediated acute rejection and 38 patients were evaluated as stable. Serum was collected after the diagnosis of acute rejection or one month after transplantation. The concentrations of MIG (median, 4,271 pg/ml), IP-10 (median, 686.7 pg/ml) and I-TAC (median, 44.32 pg/ml) in the serum during an acute rejection episode were significantly higher compared with those of the stable patients (MIG, P=0.0002; IP-10, P=0.0001; I-TAC, P=0.0103; vs. the stable function group, P<0.05). Based on the receiver-operating characteristic (ROC) curve, the joint detection of MIG, IP-10 and I-TAC in the serum using Luminex analysis may constitute a non-invasive and efficient method for the early prediction of T cell-mediated acute rejection following kidney transplantation.

A novel CXCL10-based GPI-anchored fusion protein as adjuvant in NK-based tumor therapy

Background

Cellular therapy is a promising therapeutic strategy for malignant diseases. The efficacy of this therapy can be limited by poor infiltration of the tumor by immune effector cells. In particular, NK cell infiltration is often reduced relative to T cells. A novel class of fusion proteins was designed to enhance the recruitment of specific leukocyte subsets based on their expression of a given chemokine receptor. The proteins are composed of an N-terminal chemokine head, the mucin domain taken from the membrane-anchored chemokine CX3CL1, and a C-terminal glycosylphosphatidylinositol (GPI) membrane anchor replacing the normal transmembrane domain allowing integration of the proteins into cell membranes when injected into a solid tumor. The mucin domain in conjunction with the chemokine head acts to specifically recruit leukocytes expressing the corresponding chemokine receptor.

Methodology/Principal Findings

A fusion protein comprising a CXCL10 chemokine head (CXCL10-mucin-GPI) was used for proof of concept for this approach and expressed constitutively in Chinese Hamster Ovary cells. FPLC was used to purify proteins. The recombinant proteins efficiently integrated into cell membranes in a process dependent upon the GPI anchor and were able to activate the CXCR3 receptor on lymphocytes. Endothelial cells incubated with CXCL10-mucin-GPI efficiently recruited NK cells in vitro under conditions of physiologic flow, which was shown to be dependent on the presence of the mucin domain. Experiments conducted in vivo using established tumors in mice suggested a positive effect of CXCL10-mucin-GPI on the recruitment of NK cells.

Conclusions

The results suggest enhanced recruitment of NK cells by CXCL10-mucin-GPI. This class of fusion proteins represents a novel adjuvant in cellular immunotherapy. The underlying concept of a chemokine head fused to the mucin domain and a GPI anchor signal sequence may be expanded into a broader family of reagents that will allow targeted recruitment of cells in various settings.

Homing characteristics of donor T cells after experimental allogeneic bone marrow transplantation and posttransplantation therapy for multiple myeloma

Relapse and graft-versus-host disease remain major problems associated with allogeneic bone marrow (BM) transplantation (allo-BMT) and posttransplantation therapy in patients with multiple myeloma (MM) and other hematologic malignancies. A possible strategy for selectively enhancing the graft-versus-myeloma response and possibly reducing graft-versus-host disease is to increase the migration of alloreactive T cells toward the MM-containing BM. In the present study, we characterized the BM-homing behavior of donor-derived effector T cells in a novel allo-BMT model for the treatment of MM. We observed that posttransplantation immunotherapy consisting of donor lymphocyte infusion (DLI) and vaccination with minor histocompatibility antigen-loaded dendritic cells (DCs) was associated with prolonged survival compared with allo-BMT with no further treatment. Moreover, CD8(+) effector T cells expressing inflammatory homing receptors, including high levels of CD44, LFA-1, and inflammatory chemokine receptors, were recruited to MM-bearing BM. This was paralleled by strongly increased expression of IFN-γ and IFN-γ-inducible chemokines, including CXCL9, CXCL10, and CXCL16, especially in mice treated with DLI plus minor histocompatibility antigen-loaded DC vaccination. Remarkably, expression of the homeostatic chemokine CXCL12 was reduced. Furthermore, IFN-γ and TNF-α induced BM endothelial cells to express high levels of the inflammatory chemokines and reduced or unaltered levels of CXCL12. Finally, presentation of CXCL9 by multiple BM endothelial cell-expressed heparan sulfate proteoglycans triggered transendothelial migration of effector T cells. Taken together, our data demonstrate that both post-transplantation DLI plus miHA-loaded DC vaccination and MM growth result in an increased expression of inflammatory homing receptors on donor T cells, decreased levels of the homeostatic BM-homing chemokine CXCL12, and strong induction of inflammatory chemokines in the BM. Thus, along with increasing the population of alloreactive T cells, post-transplantation immunotherapy also might contribute to a more effective graft-versus-tumor response by switching homeostatic T cell migration to inflammation-driven migration.

Chemokines: established and novel targets in atherosclerosis

In their role as small chemotactic cytokines, chemokines are crucial mediators and regulators of leukocyte trafficking during immune surveillance and inflammation. Their involvement in the development and progression of inflammatory diseases has been subject of intense investigation. Concordantly, the chemokine system has been explored in search for therapeutic targets to prevent or treat inflammatory disorders, such as atherosclerosis. Targeting the chemokine system offers various entry points for a causative treatment of this widespread and chronic illness. Although this approach has encountered some setbacks, several innovative compounds are currently in an advanced stage of development. In this review, the current standing of this dynamic field is highlighted and the potential advantages and drawbacks of particular strategies are discussed.

Perforin-mediated cytotoxicity in non-ST elevation myocardial infarction

The aim of this investigation was to examine the role of perforin (P)-mediated cytotoxicity in the dynamics of tissue damage in patients with non-ST-segment elevation myocardial infarction (NSTEMI) treated with anti-ischaemic drugs. We enrolled 48 patients with NSTEMI in this study [age, 71.5 years; 61.5/76 (median, 25th/75th percentiles)]. The percentage of total peripheral blood P(+) lymphocytes was elevated owing to the increased frequency of P(+) cells within natural killer (NK) subsets, T and NKT cells in patients on day 1 after NSTEMI when compared with healthy controls. Positive correlations were found between cardiac troponin I plasma concentrations and the frequency of P(+) cells, P(+) T cells, P(+) NK cells and their CD56(+dim) and CD56(+bright) subsets during the first week after the NSTEMI. The expression of P in NK cells was accompanied by P-mediated cytotoxicity against K-562 targets at all days examined, except day 21, when an anti-perforin monoclonal antibody did not completely abolish the killing. The percentage of P(+) T cells, P(+) NKT cells and P(+) NK subsets was the highest on the day 1 after NSTEMI and decreased in the post-infarction period. CD56(+) lymphocytes were found in damaged myocardium, suggesting their tissue recruitment. In conclusion, patients with NSTEMI have a strong and prolonged P-mediated systemic inflammatory reaction, which may sustain autoaggressive reactions towards myocardial tissue during the development of myocardial infarction.

Interactions between coagulation and complement--their role in inflammation

The parallel expression of activation products of the coagulation, fibrinolysis, and complement systems has long been observed in both clinical and experimental settings. Several interconnections between the individual components of these cascades have also been described, and the list of shared regulators is expanding. The co-existence and interplay of hemostatic and inflammatory mediators in the same microenvironment typically ensures a successful host immune defense in compromised barrier settings. However, dysregulation of the cascade activities or functions of inhibitors in one or both systems can result in clinical manifestations of disease, such as sepsis, systemic lupus erythematosus, or ischemia-reperfusion injury, with critical thrombotic and/or inflammatory complications. An appreciation of the precise relationship between complement activation and thrombosis may facilitate the development of novel therapeutics, as well as improve the clinical management of patients with thrombotic conditions that are characterized by complement-associated inflammatory responses.

Critical role for CXC ligand 10/CXC receptor 3 signaling in the murine neonatal response to sepsis

Previous studies have suggested that neonates rely heavily on innate immunity for their antimicrobial response to bacterial infections. However, the innate immune response by neonates to bacterial infection remains poorly characterized. Here, we show that in a murine model of neonatal polymicrobial sepsis, CXC ligand 10 (CXCL10) concentrations increase in the blood and peritoneum concordant with the peritoneal recruitment of granulocytes and macrophages. Additionally, CXC receptor 3 (CXCR3) expression on elicited peritoneal macrophages and granulocytes increases following sepsis. Blockade of CXCL10 worsens not only recruitment and phagocytic function of peritoneal granulocytes and macrophages but also survival. Deletion of CXCR3 also significantly increases mortality to a septic challenge. Finally, we demonstrate that the protective adjuvant effect of pretreatment with a Toll-like receptor 4 agonist to neonatal sepsis is dependent on an endogenous CXCL10 response and that pretreatment of neonates with CXCL10 can also significantly improve macrophage and granulocyte function and modestly improve outcome to polymicrobial sepsis. Together, these data suggest a critical role for CXCL10 signaling during neonatal sepsis.

Unfractionated heparin: multitargeted therapy for delayed neurological deficits induced by subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is associated with numerous "delayed neurological deficits" (DNDs) that have been attributed to multiple pathophysiological mechanisms, including ischemia, microthrombosis, free radical damage, inflammation, and vascular remodeling. To date, effective prophylactic therapy for SAH-induced DNDs has been elusive, due perhaps to the multiplicity of mechanisms involved that render typical, single-agent therapy seemingly futile. We hypothesized that heparin, which has multiple underappreciated salutary effects, might be useful as a multitargeted prophylactic agent against SAH-induced DNDs. We performed a comprehensive review of the literature to evaluate the potential utility of heparin in targeting the multiple pathophysiological mechanisms that have been identified as contributing to SAH-induced DNDs. Our literature review revealed that unfractionated heparin can potentially antagonize essentially all of the pathophysiological mechanisms known to be activated following SAH. Heparin binds >100 proteins, including plasma proteins, proteins released from platelets, cytokines, and chemokines. Also, heparin complexes with oxyhemoglobin, blocks the activity of free radicals including reactive oxygen species, antagonizes endothelin-mediated vasoconstriction, smooth muscle depolarization, and inflammatory, growth and fibrogenic responses. Our review suggests that the use of prophylactic heparin following SAH may warrant formal study.

Stromal cells differentially regulate neutrophil and lymphocyte recruitment through the endothelium

Stromal fibroblasts modify the initial recruitment of leucocytes by endothelial cells (EC), but their effects on subsequent transendothelial migration remain unclear. Here, EC and dermal or synovial fibroblasts were cultured on opposite surfaces of 3-μm pore filters and incorporated in static or flow-based migration assays. Fibroblasts had little effect on tumour necrosis factor-α-induced transendothelial migration of neutrophils, but tended to increase the efficiency of migration away from the endothelium. Surprisingly, similar close contact between EC and fibroblasts strongly reduced lymphocyte migration in static assays, and nearly abolished stable lymphocyte adhesion from flow. Fibroblasts did not alter endothelial surface expression of adhesion molecules or messenger RNA for chemokines. Inhibition of attachment did not occur when EC-fibroblast contact was restricted by using 0.4-μm pore filters, but under these conditions pre-treatment with heparinase partially inhibited adhesion. In the 3-μm pore co-cultures, inhibition of metalloproteinase activity partially recovered lymphocyte adhesion, but addition of CXCL12 (SDF-1α) to the endothelial surface did not. Hence, the ability of EC to present activating chemokines for lymphocytes may have been enzymatically inhibited by direct contact with fibroblasts. To avoid contact, we cultured EC and fibroblasts on separate 3-μm pore filters one above the other. Here, fibroblasts promoted the transendothelial migration of lymphocytes. Fibroblasts generate CXCL12, but blockade of CXCL12 receptor had no effect on lymphocyte migration. While stromal cells can provide signal(s) promoting leucocyte migration away from the sub-endothelial space, direct cell contact (which might occur in damaged tissue) may cause disruption of chemokine signalling, specifically inhibiting lymphocyte rather than neutrophil recruitment.

CXCR3-dependent accumulation and activation of perivascular macrophages is necessary for homeostatic arterial remodeling to hemodynamic stresses

Sustained changes in blood flow modulate the size of conduit arteries through structural alterations of the vessel wall that are dependent on the transient accumulation and activation of perivascular macrophages. The leukocytic infiltrate appears to be confined to the adventitia, is responsible for medial remodeling, and resolves once hemodynamic stresses have normalized without obvious intimal changes. We report that inward remodeling of the mouse common carotid artery after ligation of the ipsilateral external carotid artery is dependent on the chemokine receptor CXCR3. Wild-type myeloid cells restored flow-mediated vascular remodeling in CXCR3-deficient recipients, adventitia-infiltrating macrophages of Gr1^low resident phenotype expressed CXCR3, the perivascular accumulation of macrophages was dependent on CXCR3 signaling, and the CXCR3 ligand IP-10 was sufficient to recruit monocytes to the adventitia. CXCR3 also contributed to selective features of macrophage activation required for extracellular matrix turnover, such as production of the transglutaminase factor XIII A subunit. Human adventitial macrophages displaying a CD14⁺/CD16⁺ resident phenotype, but not circulating monocytes, expressed CXCR3, and such cells were more frequent at sites of disturbed flow. Our observations reveal a CXCR3-dependent accumulation and activation of perivascular macrophages as a necessary step in homeostatic arterial remodeling triggered by hemodynamic stress in mice and possibly in humans as well.

The blood-brain barrier, chemokines and multiple sclerosis

The infiltration of leukocytes into the central nervous system (CNS) is an essential step in the neuropathogenesis of multiple sclerosis (MS). Leukocyte extravasation from the bloodstream is a multistep process that depends on several factors including fluid dynamics within the vasculature and molecular interactions between circulating leukocytes and the vascular endothelium. An important step in this cascade is the presence of chemokines on the vascular endothelial cell surface. Chemokines displayed along the endothelial lumen bind chemokine receptors on circulating leukocytes, initiating intracellular signaling that culminates in integrin activation, leukocyte arrest, and extravasation. The presence of chemokines at the endothelial lumen can help guide the movement of leukocytes through peripheral tissues during normal immune surveillance, host defense or inflammation. The expression and display of homeostatic or inflammatory chemokines therefore critically determine which leukocyte subsets extravasate and enter the peripheral tissues. Within the CNS, however, infiltrating leukocytes that cross the endothelium face additional boundaries to parenchymal entry, including the abluminal presence of localizing cues that prevent egress from perivascular spaces. This review focuses on the differential display of chemokines along endothelial surfaces and how they impact leukocyte extravasation into parenchymal tissues, especially within the CNS. In particular, the display of chemokines by endothelial cells of the blood brain barrier may be altered during CNS autoimmune disease, promoting leukocyte entry into this immunologically distinct site. Recent advances in microscopic techniques, including two-photon and intravital imaging have provided new insights into the mechanisms of chemokine-mediated capture of leukocytes within the CNS.

Low molecular weight heparin for the treatment of retinal vein occlusion: a systematic review and meta-analysis of randomized trials

Retinal vein occlusion is a frequent cause of visual loss for which few effective therapies are available. Anticoagulation with low molecular weight heparin might be of value in its treatment. We conducted a systematic review and meta analysis of randomized trials evaluating the effect of low molecular weight heparin in patients with retinal vein occlusion. Data sources included MEDLINE, EMBASE, HealthSTAR, the Cochrane Library, Lilacs, the Investigative Ophthalmology and Visual Science database and gray literature. Main outcome was the mean difference between the visual acuity measured at baseline and at six months expressed in the logMAR scale. Secondary outcome was a composite of any adverse ocular outcome including: worsening of visual acuity, visual fields or fluorescein angiography, or development of iris neovascularization, any neovascularization or neovascular glaucoma. Subgroup analyses for branch versus central retinal vein occlusion were conducted. We identified 1,084 references of which 3 studies comparing low molecular weight heparin with aspirin (229 evaluable patients) were included. Overall, the pooled mean visual acuity difference was -0.23 logMAR (95% CI -0.38, -0.09; P=0.002) in favor of low molecular weight heparin. Low molecular weight heparin was associated with a 78% risk reduction for developing any adverse ocular outcome (pooled RR 0.22; 95% CI 0.10, 0.46; P<0.001). In subgroup analyses benefits seemed lower in branch retinal vein occlusion. No increased vitreous hemorrhages were observed. In patients with retinal vein occlusion treatment with low molecular weight heparin seems to be associated with improvement in the visual acuity and less adverse ocular outcomes. These benefits might differ in patients with central as opposed to branch retinal vein occlusion. Further studies are required to confirm these findings and clarify its benefits in specific subgroups of patients before definitive recommendations can be made.

Simulation of intra-amniotic infection and the fetal inflammatory response in a novel ex-vivo human umbilical cord perfusion model

OBJECTIVE

We aimed to design and test an ex-vivo human umbilical cord (HUC) perfusion model simulating a fetal inflammatory response (FIR) during intra-amniotic infection.

STUDY DESIGN

A 2-chamber model was designed to accommodate 2 pieces of umbilical cord. Cord perfusion was performed with placental blood. Intra-amniotic exposure to infectious organisms was simulated by adding lipopolysaccharide to the artificial amniotic fluid (AAF) compartment. As a measure of inflammatory response, we used interleukin 8 (IL-8) concentration in AAF and plasma by enzyme-linked immunosorbent assay (ELISA). Wilcoxon signed rank test was used for statistical analysis.

RESULTS

We established a stable physiological setup. Results revealed significantly elevated plasma IL-8 concentrations (n = 6, P < .05) in the blood compartment of umbilical cords exposed to lipopolysaccharide. Concentrations within AAF were not significantly elevated (n = 6, P = .3095).

CONCLUSION

Simulation of a FIR in an ex-vivo model of HUC perfusion under physiological conditions is possible. Further work is necessary to establish histological funisitis.

The role of chemokines in recruitment of immune cells to the artery wall and adipose tissue

The role of the immune system is to recognize pathogens, tumor cells or dead cells and to react with a very specific and localized response. By taking advantage of a highly sophisticated system of chemokines and chemokine receptors, leukocytes such as neutrophils, macrophages, and T-lymphocytes are targeted to the precise location of inflammation. While this is a beneficial process for acute infection and inflammation, recruitment of immune cells to sites of chronic inflammation can be detrimental. It is becoming clear that these inflammatory cells play a significant role in the initiation and progression of metabolic disorders such as atherosclerosis and insulin resistance by infiltrating the artery wall and adipose tissue (AT), respectively. Data from human studies indicate that elevated plasma levels of chemokines are correlated with these metabolic diseases. Recruitment of macrophages to the artery wall is well known to be one of the first steps in early atherosclerotic lesion formation. Likewise, recruitment of macrophages to AT is thought to contribute to insulin resistance associated with obesity. Based on this knowledge, much recent work in these areas has focused on the role of chemokines in attracting immune cells (monocytes/macrophages in particular) to these 2 sites. Thus, understanding the potential for chemokines to contribute to metabolic disease can help direct studies of chemokines as therapeutic targets. In this article, we will review current literature regarding the role of chemokines in atherosclerosis and obesity-related insulin resistance. We will focus on novel work showing that chemokine secretion from endothelial cells, platelets, and adipocytes can contribute to immune cell recruitment, with a diagram showing the time course of chemokine expression and leukocyte recruitment to AT. We will also highlight a few of the less-commonly known chemokine-chemokine receptor pairs. Finally, we will discuss the potential for chemokines as therapeutic targets for treatment of atherosclerosis and insulin resistance.

Effects of acute hypervolaemic haemodilution on the expression of plasma interferon-inducible protein-10 and bactericidal/permeability-increasing protein in patients undergoing total hip replacement

This prospective, randomized controlled study evaluated the effects of acute hypervolaemic haemodilution (AHH) on the expression of plasma interferon-inducible protein-10 (IP-10) and bactericidal/permeability-increasing protein (BPI) in patients undergoing elective total hip replacement. Twenty patients were randomized to receive an infusion of either hydroxyethyl starch (HES group) or lactated Ringer's solution (LR group) immediately after anaesthesia. Plasma concentrations of IP-10 and BPI were measured before anaesthesia (baseline), at the start of surgery, 30 min after the start of surgery and at the end of surgery. Blood loss and the volume of blood transfused were significantly lower in the HES group compared with the LR group. Compared with baseline, IP-10 and BPI concentrations increased significantly in both groups 30 min after the start of surgery. The IP-10 concentrations were significantly lower and BPI concentrations significantly higher in the HES group compared with the LR group 30 min after the start of surgery and at the end of surgery. It is concluded that AHH with HES may be helpful in ameliorating immune function during total hip replacement and in reducing blood loss and the extent of blood transfusion.

T cell extravasation: demonstration of synergy between activation of CXCR3 and the T cell receptor

Endothelial cells present chemokines to T cells and can also stimulate the T cell antigen receptor by presentation of peptide–MHC antigen complexes. This study was designed to investigate the potential synergy between stimulation of the chemokine receptor CXCR3 and the human T cell receptor complex. Transendothelial T cell migration towards CXCL10 was modified by crosslinking CD3 immediately before addition to the endothelium. When resting endothelium was used, T cells which had been activated by crosslinking CD3 for only 1 min showed a significant reduction (p < 0.0001) in migration when compared with untreated T cells. By contrast, endothelial cells which had been activated by stimulation with interferon-γ and tumour necrosis factor-α supported a specific increase in the migration of activated T cells; this was most apparent after CD3 had been activated for 90 min (p < 0.0001). The molecular basis for synergy between CXCR3 and the T cell receptor complex was investigated by measurement of fluorescence resonance energy transfer. This showed that CXCL10 induced a close (<10 nm) spatial association between CXCR3 and the CD3ɛ subunit on the cell-surface. These data demonstrate that stimulation of both CXCR3 and the T cell receptor has the potential to enhance specifically both the proliferation and extravasation of specific T cells during episodes of local inflammation.

Interferon gamma: a master regulator of atherosclerosis

Atherosclerosis is a chronic inflammatory disease that is characterized by the development of fibrotic plaques in the arterial wall. The disease exhibits a complex aetiology and its progression is influenced by a number of environmental and genetic risk factors. The cytokine interferon-gamma (IFN-gamma), a key regulator of immune function, is highly expressed in atherosclerotic lesions and has emerged as a significant factor in atherogenesis. Evidence from both mouse models of atherosclerosis and in vitro cell culture has suggested that the role of IFN-gamma is complex since both pro- and anti-atherogenic actions have been affiliated to it. This review will focus on evaluating the contribution of IFN-gamma to atherosclerosis and, in particular, how it regulates immune responses to the disease.

Tromboflebite superficial: epidemiologia, fisiopatologia, diagnóstico e tratamento

A tromboflebite superficial de membros inferiores é doença de ocorrência comum, estando associada a diversas condições clínicas e cirúrgicas. Historicamente considerada doença benigna, devido à sua localização superficial e ao fácil diagnóstico, o tratamento foi conservador durante muito tempo, na maioria dos casos. Entretanto, relatos recentes de freqüências altas de complicações tromboembólicas associadas - 22 a 37% para trombose venosa profunda e até 33% para embolia pulmonar - alertaram para a necessidade de abordagens diagnósticas e terapêuticas mais amplas, visando diagnosticar e tratar essas possíveis complicações. A possibilidade da coexistência dessas e de outras desordens sistêmicas (colagenoses, neoplasias, trombofilias) interfere na avaliação e influencia a conduta terapêutica, que pode ser clínica, cirúrgica ou combinada. No entanto, devido à falta de ensaios clínicos controlados e às incertezas quanto a sua história natural, o diagnóstico e o tratamento da tromboflebite superficial continuam indefinidos. Neste trabalho, foi feita uma revisão da literatura analisando-se a epidemiologia, fisiopatologia e estado atual do diagnóstico e tratamento da tromboflebite superficial.

Vein wall re-endothelialization after deep vein thrombosis is improved with low-molecular-weight heparin

OBJECTIVE

Vein wall endothelial turnover after stasis deep vein thrombosis (DVT) has not been well characterized. The purpose of this study was to quantify re-endothelialization after DVT and determine if low-molecular-weight heparin (LMWH) therapy affects this process.

METHODS

Stasis DVT was generated in the rat by inferior vena cava ligation, with harvest at 1, 4, and 14 days. Immunohistologic quantification of vascular smooth muscle cells and luminal endothelialization was estimated by positive staining for alpha-smooth muscle actin and von Willebrand factor, respectively. In separate experiments, rats were treated either before or after DVT with subcutaneous LMWH (3 mg/kg daily) until harvesting at 4 and 14 days. The inferior vena cava was processed for histologic analysis or was processed for organ culture after the thrombus was gently removed. The vein wall was stimulated in vitro with interleukin-1beta (1 ng/mL), and the supernatant was processed at 48 hours for nitric oxide. Cells were processed by real-time polymerase chain reaction for endothelial nitric oxide synthase, inducible nitric oxide synthase, cyclooxygenase-1 and -2, and thrombomodulin at 4 and 14 days, and collagen I and III at 14 days. Comparisons were done with analysis of variance or t test. A P < .05 was significant.

RESULTS

Thrombus size peaked at 4 days, whereas luminal re-endothelialization increased over time (1 day, 11% +/- 2%; 4 days, 23% +/- 4%; 14 days, 64% +/- 7% (+) von Willebrand factor staining; P < .01, n = 3 to 4, compared with non-DVT control). Similarly, vascular smooth muscle cell staining was lowest at day 1 and gradually returned to baseline by 14 days. Both before and after DVT, LMWH significantly increased luminal re-endothelialization, without a difference in thrombus size at 4 days, but no significant difference was noted at 14 days despite smaller thrombi with LMWH treatment. Pretreatment with LMWH was associated with increased vascular smooth muscle cell area and recovery of certain inducible endothelial specific genes. No significant difference in nitric oxide levels in the supernatant was found at 4 days. At 14 days, type III collagen was significantly elevated with LMWH treatment.

CONCLUSIONS

Venous re-endothelialization occurs progressively as the DVT resolves and can be accelerated with LMWH treatment, although this effect appears limited to the early time frame. These findings may have clinical relevance for LMWH timing and treatment compared with mechanical forms of therapy.

CLINICAL RELEVANCE

How the vein wall endothelium responds after deep vein thrombosis (DVT) has not been well documented owing to limited human specimens. This report shows that low-molecular-weight heparin accelerates or protects the endothelium and preserves medial smooth muscle cell integrity after DVT, but that this effect is limited to a relatively early time period. Although most DVT prophylaxis is pharmacologic (a heparin agent), use of nonpharmacologic measures is also common. The use of heparin prophylaxis, compared with after DVT treatment, and the acceleration of post-DVT re-endothelialization require clinical correlation.

Evolving functions of endothelial cells in inflammation

Inflammation is usually analysed from the perspective of tissue-infiltrating leukocytes. Microvascular endothelial cells at a site of inflammation are both active participants in and regulators of inflammatory processes. The properties of endothelial cells change during the transition from acute to chronic inflammation and during the transition from innate to adaptive immunity. Mediators that act on endothelial cells also act on leukocytes and vice versa. Consequently, many anti-inflammatory therapies influence the behaviour of endothelial cells and vascular therapeutics influence inflammation. This Review describes the functions performed by endothelial cells at each stage of the inflammatory process, emphasizing the principal mediators and signalling pathways involved and the therapeutic implications.

Low molecular weight heparin treatment decreases MMP-9 plasma activity in patients with abdominal aortic aneurysm

Large abdominal aortic aneurysms (AAAs) are associated with coagulation abnormalities, which are significantly reduced by low molecular weight heparin (LMWH). Considering anti-inflammatory properties of heparin we verified, whether LMWH influences MMP-2/-9 in AAA patients. The study involved 26 AAA individuals, 10 patients with coagulation abnormalities received LMWH and 16 were a control group. The plasma activity of MMP-2/-9 was measured using zymography. We found that, in addition to the reduction of coagulation abnormalities, LMWH treatment was associated with the decreased MMP-9 but not MMP-2 activity. Therefore, LMWH use could be considered as a valuable pretreatment before an elective aneurysm repair.