The chemokine repertoire of human dermal microvascular endothelial cells and its regulation by inflammatory cytokines

Cellular and Molecular Processes in Wound Healing

This review summarizes the recent knowledge of the cellular and molecular processes that occur during wound healing. However, these biological mechanisms have yet to be defined in detail; this is demonstrated by the fact that alterations of events to pathological states, such as keloids, consisting of the excessive formation of scars, have consequences yet to be defined in detail. Attention is also dedicated to new therapies proposed for these kinds of pathologies. Awareness of these scientific problems is important for experts of various disciplines who are confronted with these kinds of presentations daily.

Role of Exercise Intensity on Th1/Th2 Immune Modulations During the COVID-19 Pandemic

The COVID-19 pandemic has led to several pioneering scientific discoveries resulting in no effective solutions with the exception of vaccination. Moderate exercise is a significant non-pharmacological strategy, to reduce the infection-related burden of COVID-19, especially in patients who are obese, elderly, and with additional comorbidities. The imbalance of T helper type 1 (Th1) or T helper type 2 (Th2) cells has been well documented among populations who have suffered as a result of the COVID-19 pandemic, and who are at maximum risk of infection and mortality. Moderate and low intensity exercise can benefit persons at risk from the disease and survivors by favorable modulation in Th1/Th2 ratios. Moreover, in COVID-19 patients, mild to moderate intensity aerobic exercise also increases immune system function but high intensity aerobic exercise may have adverse effects on immune responses. In addition, sustained hypoxia in COVID-19 patients has been reported to cause organ failure and cell death. Hypoxic conditions have also been highlighted to be triggered in COVID-19-susceptible individuals and COVID-19 survivors. This suggests that hypoxia inducible factor (HIF 1α) might be an important focus for researchers investigating effective strategies to minimize the effects of the pandemic. Intermittent hypoxic preconditioning (IHP) is a method of exposing subjects to short bouts of moderate hypoxia interspersed with brief periods of normal oxygen concentrations (recovery). This methodology inhibits the production of pro-inflammatory factors, activates HIF-1α to activate target genes, and subsequently leads to a higher production of red blood cells and hemoglobin. This increases angiogenesis and increases oxygen transport capacity. These factors can help alleviate virus induced cardiopulmonary hemodynamic disorders and endothelial dysfunction. Therefore, during the COVID-19 pandemic we propose that populations should engage in low to moderate exercise individually designed, prescribed and specific, that utilizes IHP including pranayama (yoga), swimming and high-altitude hiking exercise. This would be beneficial in affecting HIF-1α to combat the disease and its severity. Therefore, the promotion of certain exercises should be considered by all sections of the population. However, exercise recommendations and prescription for COVID-19 patients should be structured to match individual levels of capability and adaptability.

Hsa-miR-605 regulates the proinflammatory chemokine CXCL5 in complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by inflammation and debilitating pain. CRPS patients with pain refractory to more conventional analgesics can be treated with subanesthetic doses of ketamine. Our previous studies found that poor responders to ketamine had a 22-fold downregulation of the miRNA hsa-miR-605 in blood prior to ketamine treatment. Hence, we sought to investigate the functional significance of miR-605 downregulation and its impact on target gene expression, as investigating target mRNAs of differentially expressed miRNAs can provide important insights on aberrant gene expression that may contribute to disease etiology. Using a bioinformatics prediction, we identified that miR-605 can target the proinflammatory chemokine CXCL5, which plays a role in leukocyte recruitment and activation. We hypothesized that downregulation of miR-605 in poor responders to ketamine could increase CXCL5 expression and thereby contribute to inflammation in these patients. We confirmed that miR-605 regulates CXCL5 by using a miRNA mimic and inhibitor in human primary endothelial cells. Inhibition of miR-605 increased CXCL5 secretion and migration of human monocytic cells, thereby demonstrating a functional impact of miR-605 on chemotaxis. Additionally, CXCL5 mRNA was upregulated in whole blood from poor responders to ketamine, and CXCL5 protein was increased in plasma from CRPS patients. Thus, our studies suggest that miR-605 regulation of CXCL5 can regulate inflammation.

The Contribution of Chemoattractant GPCRs, Formylpeptide Receptors, to Inflammation and Cancer

A hallmark of inflammatory responses is leukocyte mobilization, which is mediated by pathogen and host released chemotactic factors that activate Gi-protein-coupled seven-transmembrane receptors (GPCRs) on host cell surface. Formylpeptide receptors (FPRs, Fprs in mice) are members of the chemoattractant GPCR family, shown to be critical in myeloid cell trafficking during infection, inflammation, immune responses, and cancer progression. Accumulating evidence demonstrates that both human FPRs and murine Fprs are involved in a number of patho-physiological processes because of their expression on a wide variety of cell types in addition to myeloid cells. The unique capacity of FPRs (Fprs) to interact with numerous structurally unrelated chemotactic ligands enables these receptors to participate in orchestrated disease initiation, progression, and resolution. One murine Fpr member, Fpr2, and its endogenous agonist peptide, Cathelicidin-related antimicrobial peptide (CRAMP), have been demonstrated as key mediators of colon mucosal homeostasis and protection from inflammation and associated tumorigenesis. Recent availability of genetically engineered mouse models greatly expanded the understanding of the role of FPRs (Fprs) in pathophysiology that places these molecules in the list of potential targets for therapeutic intervention of diseases.

The Interplay Between Lymphatic Vessels and Chemokines

Chemokines are a family of small protein cytokines that act as chemoattractants to migrating cells, in particular those of the immune system. They are categorized functionally as either homeostatic, constitutively produced by tissues for basal levels of cell migration, or inflammatory, where they are generated in association with a pathological inflammatory response. While the extravasation of leukocytes via blood vessels is a key step in cells entering the tissues, the lymphatic vessels also serve as a conduit for cells that are recruited and localized through chemoattractant gradients. Furthermore, the growth and remodeling of lymphatic vessels in pathologies is influenced by chemokines and their receptors expressed by lymphatic endothelial cells (LECs) in and around the pathological tissue. In this review we summarize the diverse role played by specific chemokines and their receptors in shaping the interaction of lymphatic vessels, immune cells, and other pathological cell types in physiology and disease.

Impact of Human Dermal Microvascular Endothelial Cells on Primary Dermal Fibroblasts in Response to Inflammatory Stress

The aim of the present study was to evaluate the impact of the microenvironment produced by dermal microvascular endothelial cells, secondary to a pro-inflammatory challenge, on 2D culture models using dermal fibroblasts and in 3D reconstructed skin model using dermal fibroblasts and keratinocytes from healthy donors. We hypothesized that specific microvascular endothelial low grade inflammation could change fibroblasts phenotype and be involved in extracellular matrix (ECM) modification and skin alteration. Following IFNγ, TNFα, IL-1β pro-inflammatory stress on Human Dermal Endothelial Cells (HDMEC) we observed the increased release of Chemokine ligand 2 (CCL2), IL-6 and IL-8 but not VEGF-A in the conditioned medium (CM). The subsequent addition of this endothelial pro-inflammatory CM in dermal fibroblasts revealed an upregulation of IL6, IL8 and CCL2 but no NF-κB gene expression. The resulting ECM formation was impaired with a reduction of the collagen 1 network and a decrease in COL1A1 gene expression in 2D and 3D models. Collagen 1 and pro-LOX protein expression were significantly reduced confirming an impairment of the collagen network related to endothelial inflammation secretion. To conclude, this work showed that, without any immune cells, the endothelial secretion in response to a pro-inflammatory stress is able to activate the fibroblasts that will maintain the pro-inflammatory environment and exacerbate ECM degradation.

Transcriptomics and Immunological Analyses Reveal a Pro-Angiogenic and Anti-Inflammatory Phenotype for Decidual Endothelial Cells

Background: In pregnancy, excessive inflammation and break down of immunologic tolerance can contribute to miscarriage. Endothelial cells (ECs) are able to orchestrate the inflammatory processes by secreting pro-inflammatory mediators and bactericidal factors by modulating leakiness and leukocyte trafficking, via the expression of adhesion molecules and chemokines. The aim of this study was to analyse the differences in the phenotype between microvascular ECs isolated from decidua (DECs) and ECs isolated from human skin (ADMECs). Methods: DECs and ADMECs were characterized for their basal expression of angiogenic factors and adhesion molecules. A range of immunological responses was evaluated, such as vessel leakage, reactive oxygen species (ROS) production in response to TNF-α stimulation, adhesion molecules expression and leukocyte migration in response to TNF-α and IFN-γ stimulation. Results: DECs produced higher levels of HGF, VEGF-A and IGFBP3 compared to ADMECs. DECs expressed adhesion molecules, ICAM-2 and ICAM-3, and a mild response to TNF-α was observed. Finally, DECs produced high levels of CXCL9/MIG and CXCL10/IP-10 in response to IFN-γ and selectively recruited Treg lymphocytes. Conclusion: DEC phenotype differs considerably from that of ADMECs, suggesting that DECs may play an active role in the control of immune response and angiogenesis at the foetal-maternal interface.

Regulation of inflammation by members of the formyl-peptide receptor family

Inflammation is associated with a variety of diseases. The hallmark of inflammation is leukocyte infiltration at disease sites in response to pathogen- or damage-associated chemotactic molecular patterns (PAMPs and MAMPs), which are recognized by a superfamily of seven transmembrane, Gi-protein-coupled receptors (GPCRs) on cell surface. Chemotactic GPCRs are composed of two major subfamilies: the classical GPCRs and chemokine GPCRs. Formyl-peptide receptors (FPRs) belong to the classical chemotactic GPCR subfamily with unique properties that are increasingly appreciated for their expression on diverse host cell types and the capacity to interact with a plethora of chemotactic PAMPs and MAMPs. Three FPRs have been identified in human: FPR1-FPR3, with putative corresponding mouse counterparts. FPR expression was initially described in myeloid cells but subsequently in many non-hematopoietic cells including cancer cells. Accumulating evidence demonstrates that FPRs possess multiple functions in addition to controlling inflammation, and participate in the processes of many pathophysiologic conditions. They are not only critical mediators of myeloid cell trafficking, but are also implicated in tissue repair, angiogenesis and protection against inflammation-associated tumorigenesis. A series recent discoveries have greatly expanded the scope of FPRs in host defense which uncovered the essential participation of FPRs in step-wise trafficking of myeloid cells including neutrophils and dendritic cells (DCs) in host responses to bacterial infection, tissue injury and wound healing. Also of great interest is the FPRs are exploited by malignant cancer cells for their growth, invasion and metastasis. In this article, we review the current understanding of FPRs concerning their expression in a vast array of cell types, their involvement in guiding leukocyte trafficking in pathophysiological conditions, and their capacity to promote the differentiation of immune cells, their participation in tumor-associated inflammation and cancer progression. The close association of FPRs with human diseases and cancer indicates their potential as targets for the development of therapeutics.

T Lymphocyte-Endothelial Interactions: Emerging Understanding of Trafficking and Antigen-Specific Immunity

Antigen-specific immunity requires regulated trafficking of T cells in and out of diverse tissues in order to orchestrate lymphocyte development, immune surveillance, responses, and memory. The endothelium serves as a unique barrier, as well as a sentinel, between the blood and the tissues, and as such it plays an essential locally tuned role in regulating T cell migration and information exchange. While it is well established that chemoattractants and adhesion molecules are major determinants of T cell trafficking, emerging studies have now enumerated a large number of molecular players as well as a range of discrete cellular remodeling activities (e.g., transmigratory cups and invadosome-like protrusions) that participate in directed migration and pathfinding by T cells. In addition to providing trafficking cues, intimate cell-cell interaction between lymphocytes and endothelial cells provide instruction to T cells that influence their activation and differentiation states. Perhaps the most intriguing and underappreciated of these "sentinel" roles is the ability of the endothelium to act as a non-hematopoietic "semiprofessional" antigen-presenting cell. Close contacts between circulating T cells and antigen-presenting endothelium may play unique non-redundant roles in shaping adaptive immune responses within the periphery. A better understanding of the mechanisms directing T cell trafficking and the antigen-presenting role of the endothelium may not only increase our knowledge of the adaptive immune response but also empower the utility of emerging immunomodulatory therapeutics.

The Role of Chemokines in Fibrotic Wound Healing

Significance: Main dermal forms of fibroproliferative disorders are hypertrophic scars (HTS) and keloids. They often occur after cutaneous wound healing after skin injury, or keloids even form spontaneously in the absence of any known injury. HTS and keloids are different in clinical performance, morphology, and histology, but they all lead to physical and psychological problems for survivors. Recent Advances: Although the mechanism of wound healing at cellular and tissue levels has been well described, the molecular pathways involved in wound healing, especially fibrotic healing, is incompletely understood. Critical Issues: Abnormal scars not only lead to increased health-care costs but also cause significant psychological problems for survivors. A plethora of therapeutic strategies have been used to prevent or attenuate excessive scar formation; however, most therapeutic approaches remain clinically unsatisfactory. Future Directions: Effective care depends on an improved understanding of the mechanisms that cause abnormal scars in patients. A thorough understanding of the roles of chemokines in cutaneous wound healing and abnormal scar formation will help provide more effective preventive and therapeutic strategies for dermal fibrosis as well as for other proliferative disorders.

Chemokine Involvement in Fetal and Adult Wound Healing

Significance: Fetal wounds heal with a regenerative phenotype that is indistinguishable from surrounding skin with restored skin integrity. Compared to this benchmark, all postnatal wound healing is impaired and characterized by scar formation. The biologic basis of the fetal regenerative phenotype can serve as a roadmap to recapitulating regenerative repair in adult wounds. Reduced leukocyte infiltration, likely mediated, in part, through changes in the chemokine milieu, is a fundamental feature of fetal wound healing. Recent Advances: The contributions of chemokines to wound healing are a topic of active investigation. Recent discoveries have opened the possibility of targeting chemokines therapeutically to treat disease processes and improve healing capability, including the possibility of achieving a scarless phenotype in postnatal wounds. Critical Issues: Successful wound healing is a complex process, in which there is a significant interplay between multiple cell types, signaling molecules, growth factors, and extracellular matrix. Chemokines play a crucial role in this interplay and have been shown to have different effects in various stages of the healing process. Understanding how these chemokines are locally produced and regulated during wound healing and how the chemokine milieu differs in fetal versus postnatal wounds may help us identify ways in which we can target chemokine pathways. Future Directions: Further studies on the role of chemokines and their role in the healing process will greatly advance the potential for using these molecules as therapeutic targets.

Thiram activates NF-kappaB and enhances ICAM-1 expression in human microvascular endothelial HMEC-1 cells

Thiram (TMTD) is a fungicidal and bactericidal agent used as antiseptic, seed disinfectant and animal repellent. In the light of known properties, thiram is considered to be used as an inhibitor of angiogenesis and/or inflammation. Since angiogenesis requires the growth of vascular endothelial cells we have used microvascular endothelial cell line HMEC-1 to elucidate the effect of thiram on normal and stimulated cells. We cultured HMEC-1 cells in the presence of thiram at low concentration (0.5 µg/mL or 2 µg/mL) (0.2 µM or 0.8 µM) or TNF-α (10 ng/mL) alone, and thiram together with TNF-α. TNF-α was used as a cytokine that triggers changes characteristic for inflammatory state of the cell. We carried out an in vitro study aimed at assessing generation of reactive oxygen species (ROS), activation of NF-κB, and expression of cell adhesion molecules ICAM-1, VCAM-1, PECAM-1. It was found that TMTD produced ROS and activated NF-κB. Activation of NF-κB was concurrent with an increase in ICAM-1 expression on the surface of HMEC-1 cells. ICAM-1 reflects intensity of inflammation in endothelial cell milieu. The expression of VCAM-1 and PECAM-1 on these cells was not changed by thiram. It was also found that stimulation of the HMEC-1 cells with the pro-inflammatory cytokine TNF-α caused activation of ICAM-1 and VCAM-1 expression with concomitant decrease of PECAM-1 cell surface expression above the control levels. Treatment with thiram and TNF-α changed cellular response compared with effects observed after treatment with TNF-α alone, i.e. further increase of ICAM-1 expression and impairment of the TNF-α effect on PECAM-1 and VCAM-1 expression. This study demonstrated that thiram acts as a pro-oxidant, and elicits in endothelial cell environment effects characteristic for inflammation. However, when it is present concurrently with pro-inflammatory cytokine TNF-α interferes with its action.

Formylpeptide receptors mediate rapid neutrophil mobilization to accelerate wound healing

Wound healing is a multi-phased pathophysiological process requiring chemoattractant receptor-dependent accumulation of myeloid cells in the lesion. Two G protein-coupled formylpeptide receptors Fpr1 and Fpr2 mediate rapid neutrophil infiltration in the liver of Listeria-infected mice by sensing pathogen-derived chemotactic ligands. These receptors also recognize host-derived chemotactic peptides in inflammation and injury. Here we report the capacity of Fprs to promote the healing of sterile skin wound in mice by initiating neutrophil infiltration. We found that in normal miceneutrophils rapidly infiltrated the dermis in the wound before the production of neutrophil-specific chemokines by the injured tissue. In contrast, rapid neutrophil infiltration was markedly reduced with delayed wound closure in mice deficient in both Fprs. In addition, we detected Fpr ligand activity that chemoattracted neutrophils into the wound tissue. Our study thus demonstrates that Fprs are critical for normal healing of the sterile skin wound by mediating the first wave of neutrophil infiltration.

Norepinephrine and adenosine-5'-triphosphate synergize in inducing IL-6 production by human dermal microvascular endothelial cells

Endothelial cells (ECs) play important roles in cutaneous inflammation, in part, by release of inflammatory chemokines/cytokines. Because dermal blood vessels are innervated by sympathetic nerves, the sympathetic neurotransmitter norepinephrine (NE) and the co-transmitter adenosine-5'-triphosphate (ATP) may regulate expression of EC inflammatory factors. We focused on IL-6 regulation because it has many inflammatory and immune functions, including participation in Th17 cell differentiation. Strikingly, NE and ATP synergistically induced release of IL-6 by a human dermal microvascular endothelial cell line (HMEC-1). Adrenergic antagonist and agonist studies indicated that the effect of NE on induced IL-6 release is primarily mediated by β2-adrenergic receptors (ARs). By real-time PCR IL-6 mRNA was also synergistically induced in HMEC-1 cells. This synergistic effect of NE and ATP was reproduced in primary human dermal endothelial cells (pHDMECs) and is also primarily mediated by β2-ARs. Under conditions of stress, activation of the symphathetic nervous system may lead to release of ATP and NE by sympathetic nerves surrounding dermal blood vessels with induction of IL-6 production by ECs. IL-6 may then participate in immune and inflammatory processes including generation of Th17 cells. Production of IL-6 in this manner might explain stress-induced exacerbation of psoriasis, and perhaps, other skin disorders involving Th17-type immunity.

N-acetyl-S-farnesyl-l-cysteine suppresses chemokine production by human dermal microvascular endothelial cells

Isoprenylcysteine (IPC) molecules modulate G-protein-coupled receptor signalling. The archetype of this class is N-acetyl-S-farnesyl-l-cysteine (AFC). Topical application of AFC locally inhibits skin inflammation and elicitation of contact hypersensitivity in vivo. However, the mechanism of these anti-inflammatory effects is not well understood. Dermal microvascular endothelial cells (ECs) are involved in inflammation, in part, by secreting cytokines that recruit inflammatory cells. We have previously shown that the sympathetic nerve cotransmitter adenosine-5'-triphosphate (ATP) and adenosine-5'-O-(3-thio) triphosphate (ATPγS), an ATP analogue that is resistant to hydrolysis, increase secretion of the chemokines CXCL8 (interleukin-8), CCL2 (monocyte chemotactic protein-1) and CXCL1 (growth-regulated oncogene α) by dermal microvascular ECs. Production of these chemokines can also be induced by the exposure to the proinflammatory cytokine TNFα. We have now demonstrated that AFC dose-dependently inhibits ATP-, ATPγS- and TNFα-induced production of CXCL1, CXCL8 and CCL2 by a human dermal microvascular EC line (HMEC-1) in vitro under conditions that do not affect cell viability. Inhibition of ATPγS- or TNFα-stimulated release of these chemokines was associated with reduced mRNA levels. N-acetyl-S-geranyl-l-cysteine, an IPC analogue that is inactive in inhibiting G-protein-coupled signalling, had greatly reduced ability to suppress stimulated chemokine production. AFC may exert its anti-inflammatory effects through the inhibition of chemokine production by stimulated ECs.

Analysis of the proteomic profile of chronic pressure ulcers

Analysis of the proteomic profile of pressure ulcers over time is a critical step in the identification of biomarkers of healing or nonhealing in pressure ulcers. The wound fluid from 32 subjects with 42 pressure ulcers was evaluated over 6 weeks at 15 time points. Samples specific to both the interior and the periphery of the wound bed were collected. Antibody screening arrays, isobaric tags for relative and absolute quantitation with mass spectrometry and multiplexed microarrays were used to characterize wound fluid and results were correlated with clinical outcome. Twenty-one proteins were found to distinguish between healed and chronic wounds and 19 proteins were differentially expressed between the interior and periphery of wounds. Four proteins, pyruvate kinase isozymes M1/M2, profilin-1, Ig lambda-1 chain C regions, and Ig gamma-1 chain C region, were present in lower levels for periphery samples when compared to interior samples and six proteins, keratin, type II cytoskeletal 6A (KRT6A), keratin, type I cytoskeletal 14, S100 calcium binding proteins A7, alpha-1-antitrypsin precursor, hemoglobin subunit alpha, and hemoglobin subunit beta, were present in higher levels in periphery samples when compared with interior samples. S100 calcium binding protein A6, S100 calcium binding protein A7, and soluble receptor for advanced glycation end-products had higher levels in the periphery of chronic wounds vs. the interior in planar arrays. A significant temporal trend was noted for monokine induced by gamma interferon (MIG), synonomous with chemokine (C-X-C motif) ligand 9 (CXCL9), which increased as wounds healed and remained nearly constant for ulcers that were not approaching closure.

Calcitonin gene-related peptide inhibits chemokine production by human dermal microvascular endothelial cells

This study examined whether the sensory neuropeptide calcitonin gene-related peptide (CGRP) inhibits release of chemokines by dermal microvascular endothelial cells. Dermal blood vessels are associated with nerves containing CGRP, suggesting that CGRP-containing nerves may regulate cutaneous inflammation through effects on vessels. We examined CGRP effects on stimulated chemokine production by a human dermal microvascular endothelial cell line (HMEC-1) and primary human dermal microvascular endothelial cells (pHDMECs). HMEC-1 cells and pHDMECs expressed mRNA for components of the CGRP and adrenomedullin receptors and CGRP inhibited LPS-induced production of the chemokines CXCL8, CCL2, and CXCL1 by both HMEC-1 cells and pHDMECs. The receptor activity-modifying protein (RAMP)1/calcitonin receptor-like receptor (CL)-specific antagonists CGRP₈-₃₇ and BIBN4096BS, blocked this effect of CGRP in a dose-dependent manner. CGRP prevented LPS-induced IκBα degradation and NF-κB binding to the promoters of CXCL1, CXCL8 and CCL2 in HMEC-1 cells and Bay 11-7085, an inhibitor of NF-κB activation, suppressed LPS-induced production of CXCL1, CXCL8 and CCL2. Thus, the NF-κB pathway appears to be involved in CGRP-mediated suppression of chemokine production. Accordingly, CGRP treatment of LPS-stimulated HMEC-1 cells inhibited their ability to chemoattract human neutrophils and mononuclear cells. Elucidation of this pathway may suggest new avenues for therapeutic manipulation of cutaneous inflammation.

Role of endothelial chemokines and their receptors during inflammation

Chemokines are a large group of small cytokines known for their chemotactic ability to regulate the recruitment of leukocytes to sites of inflammation. This occurs through the binding of chemokines to their receptors located on the leukocyte that results in cellular changes such as actin rearrangement and cell shape, which allow for the migration of the leukocyte. In addition to regulating leukocyte function, it is now becoming apparent that other nonhematopoetic cells, such as smooth muscle cells and endothelial cells, can also be regulated by chemokines. Studies within the past 10 years has demonstrated the presence of various chemokine receptors on endothelial cells as well as the ability of chemokines to activate these receptors resulting in various cellular responses including migration, proliferation, and cellular activation. The purpose of this review is to highlight the research that has been done to date demonstrating the important role for chemokines in regulating endothelial function during various inflammatory conditions associated with angiogenesis, homeostasis, and leukocyte transmigration. This review will focus specifically on the role of the endothelium in mediating chemokine effects associated with wound healing, atherosclerosis, and autoimmune diseases, conditions where leukocyte recruitment and angiogenesis play a major role. Recent progress in the development and implementation of therapeutics agents against these small molecules, or their receptors, will also be addressed.

Oncostatin M-enhanced vascular endothelial growth factor expression in human vascular smooth muscle cells involves PI3K-, p38 MAPK-, Erk1/2- and STAT1/STAT3-dependent pathways and is attenuated by interferon-γ

The pleiotropic cytokine oncostatin M (OSM), a member of the glycoprotein (gp)130 ligand family, plays a key role in inflammation and cardiovascular disease. As inflammation precedes and accompanies pathological angiogenesis, we investigated the effect of OSM and other gp130 ligands on vascular endothelial growth factor (VEGF) production in human vascular smooth muscle cells (SMC). Human coronary artery SMC (HCASMC) and human aortic SMC (HASMC) were treated with different gp130 ligands. VEGF protein was determined by ELISA. Specific mRNA was detected by RT-PCR. Western blotting was performed for signal transducers and activators of transcription1 (STAT1), STAT3, Akt and p38 mitogen-activated protein kinase (p38 MAPK). OSM mRNA and VEGF mRNA expression was analyzed in human carotid endaterectomy specimens from 15 patients. OSM increased VEGF production in both HCASMC and HASMC derived from different donors. OSM upregulated VEGF and OSM receptor-specific mRNA in these cells. STAT3 inhibitor WP1066, p38 MAPK inhibitors SB-202190 and BIRB 0796, extracellular signal-regulated kinase1/2 (Erk1/2) inhibitor U0126, and phosphatidylinositol 3-kinase (PI3K) inhibitors LY-294002 and PI-103 reduced OSM-induced VEGF synthesis. We found OSM expression in human atherosclerotic lesions where OSM mRNA correlated with VEGF mRNA expression. Interferon-γ (IFN-γ), but not IL-4 or IL-10, reduced OSM-induced VEGF production in vascular SMC. Our findings that OSM, which is present in human atherosclerotic lesions and correlates with VEGF expression, stimulates production of VEGF by human coronary artery and aortic SMC indicate that OSM could contribute to plaque angiogenesis and destabilization. IFN-γ reduced OSM-induced VEGF production by vascular SMC.

Thrombin induces the expression of oncostatin M via AP-1 activation in human macrophages: a link between coagulation and inflammation

Macrophages as inflammatory cells are involved in the pathogenesis of atherosclerosis that today is recognized as an inflammatory disease. Activation of coagulation leads to the late complication of atherosclerosis, namely atherothrombosis with its clinical manifestations stroke, unstable angina, myocardial infarction, and sudden cardiac death. Thus inflammation and coagulation play fundamental roles in the pathogenesis of atherosclerosis. We show that the coagulation enzyme thrombin up-regulates oncostatin M (OSM), a pleiotropic cytokine implicated in the pathophysiology of vascular disease, in human monocyte-derived macrophages (MDMs) up to 16.8-fold. A similar effect was seen in human peripheral blood monocytes and human plaque macrophages. In MDMs, the effect of thrombin on OSM was abolished by PPACK and mimicked by a PAR-1-specific peptide. Thrombin induced phosphorylation of ERK1/2 and p38 in MDMs. The ERK1/2 inhibitor PD98059 blocked the effect of thrombin on OSM production in MDMs, whereas the p38 inhibitor SB202190 had no effect. Thrombin induced translocation of c-fos and c-jun to the nucleus of MDMs. Using OSM promoter-luciferase reporter constructs transfected into MDMs, we show that a functional AP-1 site is required for promoter activation by thrombin. We present another link between coagulation and inflammation, which could impact on the pathogenesis of atherosclerosis.

Effects of Antioxidant and Nitric Oxide on Chemokine Production in TNF-α-stimulated Human Dermal Microvascular Endothelial Cells

Chemokines have been implicated convincingly in the driving of leukocyte emigration in different inflammatory reactions. Multiple signaling mechanisms are reported to be involved in intracellular activation of chemokine expression in vascular endothelial cells by various stimuli. Nevertheless, redox-regulated mechanisms of chemokine expression in human dermal microvascular endothelial cells (HDMEC) remain unclear. This study examined the effects of pyrrolidine dithiocarbamate (PDTC, 0.1 mM) and spermine NONOate (Sper-NO, 1 mM) on the secretion and gene expression of chemokines, interleukin (IL)-8, monocyte chemotactic protein (MCP)-1, regulated upon activation normal T cell expressed and secreted (RANTES), and eotaxin. This study also addresses PDTC and Sper-NO effects on activation of nuclear factor kappa B (NF-kappaB) induced by TNF-alpha (10 ng/ml). Treatment with TNF-alpha for 8 h significantly increased secretion of IL-8, MCP-1, and RANTES, but not of eotaxin, in cultured HDMEC. Up-regulation of these chemokines was suppressed significantly by pretreatment with PDTC or Sper-NO for 1 h, but not by 1 mM 8-bromo-cyclic GMP. The mRNA accumulation of IL-8, MCP-1, RANTES, and eotaxin, and activation of NF-kappaB were induced by TNF-alpha for 2 h; all were suppressed significantly by the above two pretreatments. These findings indicate that both secretion and mRNA accumulation of IL-8, MCP-1, and RANTES in HDMEC induced by TNF-alpha are inhibited significantly by pretreatment with PDTC or Sper-NO, possibly via blocking redox-regulated NF-kappaB activation. These results suggest that restoration of the redox balance using antioxidant agents or nitric oxide pathway modulators may offer new opportunities for therapeutic interventions in inflammatory skin diseases.

Tetracycline suppresses ATP gamma S-induced CXCL8 and CXCL1 production by the human dermal microvascular endothelial cell-1 (HMEC-1) cell line and primary human dermal microvascular endothelial cells

Tetracyclines (TCN) have powerful anti-inflammatory properties in addition to their anti-microbial effects. These anti-inflammatory effects are thought to play a role in inhibiting cutaneous inflammation in patients with rosacea and acne; however, the mechanism(s) of this action remains poorly understood. We have previously shown that adenosine-5'-triphosphate (ATP)gamma S, a hydrolysis-resistant ATP analogue, augments secretion of pro-inflammatory messengers by a human dermal microvascular endothelial cell line (HMEC-1). ATP released by the sympathetic nerves during stress may stimulate release of pro-inflammatory chemokines by dermal vessel endothelial cells, resulting in recruitment of inflammatory cells and exacerbation of inflammatory skin disease. Here we demonstrate that TCN inhibits ATP gamma S-induced release of pro-inflammatory mediators by HMEC-1 cells and primary human dermal microvascular endothelial cells. TCN dose-dependently inhibited ATP gamma S-induced augmentation of CXCL8 (interleukin-8) and CXCL1 (growth-regulated oncogene-alpha) production by HMEC-1 cells and primary human dermal endothelial cells in vitro. TCN and ATP gamma S did not affect HMEC-1 cell viability as determined by trypan-blue exclusion and cell counts. Inhibition of production of inflammatory mediators by endothelial cells may be one mechanism by which TCN improves inflammatory skin diseases. The ability to inhibit release of inflammatory mediators induced in HMEC-1 cells by purinergic agonists may be a useful way to screen for potential therapeutic agents for cutaneous inflammation.

A novel inflammatory pathway involved in leukocyte recruitment: role for the kinin B1 receptor and the chemokine CXCL5

The kinin B1 receptor is an inducible receptor not normally expressed but induced by inflammatory stimuli and plays a major role in neutrophil recruitment, particularly in response to the cytokine IL-1beta. However, the exact mechanism involved in this response is unclear. The aim of this study was to dissect the molecular mechanism involved, in particular to determine whether specific ELR-CXCL chemokines (specific neutrophil chemoattractants) played a role. Using intravital microscopy, we demonstrated that IL-1beta-induced leukocyte rolling, adherence, and emigration in mesenteric venules of wild-type (WT) mice, associated with an increase in B1 receptor mRNA expression, were substantially attenuated (>80%) in B1 receptor knockout mice (B1KO). This effect in B1KO mice was correlated with a selective down-regulation of IL-1beta-induced CXCL5 mRNA and protein expression compared with WT mice. Furthermore a selective neutralizing CXCL5 Ab caused profound suppression of leukocyte emigration in IL-1beta-treated WT mice. Finally, treatment of human endothelial cells with IL-1beta enhanced mRNA expression of the B1 receptor and the human (h) CXCL5 homologues (hCXCL5 and hCXCL6). This response was suppressed by approximately 50% when cells were pretreated with the B1 receptor antagonist des-Arg9-[Leu8]-bradykinin while treatment with des-Arg9-bradykinin, the B1 receptor agonist, caused a concentration-dependent increase in hCXCL5 and hCXCL6 mRNA expression. This study unveils a proinflammatory pathway centered on kinin B1 receptor activation of CXCL5 leading to leukocyte trafficking and highlights the B1 receptor as a potential target in the therapeutics of inflammatory disease.

Epidermal interleukin-8 and its receptor CXCR2 in drug-induced toxic epidermal necrolysis

BACKGROUND

In drug-induced toxic epidermal necrolysis (TEN), the epidermal destruction is associated with a slight to moderate lymphomonocytic cell infiltrate. Interleukin (IL)-8, which is a keratinocyte-derived pro-inflammatory cytokine, might be involved in this process. The IL-8 receptor CXCR2 has also been shown to be overexpressed in some epidermal disorders.

METHODS

IL-8 concentration was measured by ELISA in both serum and blister fluid from 10 patients with TEN. Data were compared with similar dosages performed in 15 cases of second-degree burn and 7 cases of bullous pemphigoid (BP). CXCR2 expression on keratinocytes was studied using immunohistochemistry on skin biopsies performed in TEN bullous lesions and clinically uninvolved skin of the same patients.

RESULTS

IL-8 was significantly overexpressed in TEN blister fluid compared with TEN serum (P = 0.0015). However, no difference was found in IL-8 concentrations present in blister fluid of TEN, second-degree burn and BP. CXCR2 was moderately expressed in the epidermis of some TEN blisters, but was never expressed in clinically uninvolved skin. CXCR2 expression was not found in the follicular epidermal root sheaths of patients with TEN.

CONCLUSIONS

These results indicate that abundant IL-8 appears to be locally produced in TEN epidermis, but this overexpression is not disease-specific. Because of the paucity of the inflammatory infiltrate in TEN, it is unlikely that IL-8 induces epidermal destruction through its chemotactic activity. Moreover, the complete absence of neutrophils in TEN lesions indicates that the major chemotactic effect of IL-8 on neutrophils is not operative in TEN skin. This implies that IL-8 activates different functions according to the local environment. CXCR2 expression on TEN keratinocytes is expressed on some necrotic keratinocytes, consistent with a discrete IL-8 proapoptotic activity. The lack of CXCR2 expression in the follicular root sheaths argues against a role for IL-8 in TEN epidermal repair.

TLR ligands and cytokines induce CXCR3 ligands in endothelial cells: enhanced CXCL9 in autoimmune arthritis

CXC chemokines are potent attractants of neutrophil granulocytes, T cells or natural killer cells. Toll-like receptors (TLR) recognize microbial components and are also activated by endogenous molecules possibly implicated in autoimmune arthritis. In contrast to CXC chemokine ligand 8 (CXCL8), no CXC chemokine receptor 3 (CXCR3) ligand (ie CXCL9, CXCL10 and CXCL11) was induced by bacterial TLR ligands in human microvascular endothelial cells (HMVEC). However, peptidoglycan (PGN), double-stranded (ds) RNA or lipopolysaccharide (LPS) (TLR2, TLR3 or TLR4 ligands, respectively) synergized with interferon-gamma (IFN-gamma) at inducing CXCL9 and CXCL10. In contrast, enhanced CXCL11 secretion was only obtained when IFN-gamma was combined with TLR3 ligand. Furthermore, flagellin, loxoribine and unmethylated CpG oligonucleotide (TLR5, TLR7 and TLR9 ligands, respectively) did not enhance IFN-gamma-dependent CXCR3 ligand production in HMVEC. In analogy with TLR ligands, tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), in combination with IFN-gamma, synergistically induced CXCL9 and CXCL11 in HMVEC and human fibroblasts, two fundamental cell types delineating the joint cavity. Etanercept, a humanized soluble recombinant p75 TNF-receptor/IgG(1)Fc fusionprotein, neutralized synergistic CXCL9 production induced by TNF-alpha plus IFN-gamma, but not synergy between IFN-gamma and the TLR ligands PGN or LPS. Synovial chemokine concentrations exemplify the physiopathological relevance of the observed in vitro chemokine production patterns. In synovial fluids of patients with spondylarthropathies (ie ankylosing spondylitis or psoriatic arthritis) or rheumatoid arthritis, significantly enhanced CXCL9, but not CXCL11 levels, were detected compared to concentrations in synovial fluids of patients with metabolic crystal-induced arthritis. Thus, CXCL9 is an important chemokine in autoimmune arthritis.

ATPgammaS enhances the production of inflammatory mediators by a human dermal endothelial cell line via purinergic receptor signaling

Adenosine 5'-triphosphate (ATP) affects multiple intra- and extracellular processes, including vascular tone and immune responses. Microvascular endothelial cells (EC) play a central role in inflammation by recruitment of inflammatory cells from blood to tissues. We hypothesized that ATP (secreted by neurons and/or released after perturbation of cutaneous cells) may influence secretion of inflammatory messengers by dermal microvascular EC through actions on purinergic P2 receptors. Addition of the hydrolysis-resistant ATP analogue, adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), to subconfluent cultures of the human microvascular endothelial cell-1 (HMEC-1) cell line led to a dose- and time-dependent increase in release of IL-6, IL-8, monocyte chemoattractant protein-1, and growth-regulated oncogene alpha. Both ATPgammaS-induced release and basal production of these proteins were significantly inhibited by the purinergic antagonists pyridoxal-5'-phosphate-6-azophenyl-2',5'-disulfonic acid (PPADS), pyridoxal-5'-phosphate-6(2'-naphthylazo-6-nitro-4',8'-disulfonate), and suramin. ATPgammaS increased expression of intercellular adhesion molecule-1 (ICAM-1), whereas suramin and PPADS decreased both ATPgammaS-induced and basal ICAM-1 expression. Using PCR, we found that HMEC-1 strongly express mRNA for the P2X(4), P2X(5), P2X(7), P2Y(2), and P2Y(11) receptors and weakly express mRNA for P2X(1) and P2X(3) receptors. Purinergic nucleotides may mediate acute inflammation in the skin and thus contribute to physiological and pathophysiological inflammation. For example, ATP may contribute to both the vasodilation and the inflammation associated with rosacea.

Differential signaling mechanisms regulate expression of CC chemokine receptor-2 during monocyte maturation

Background

Peripheral blood monocytes and monocyte-derived macrophages are key regulatory components in many chronic inflammatory pathologies of the vasculature including the formation of atherosclerotic lesions. However, the molecular and biochemical events underlying monocyte maturation are not fully understood.

Methods

We have used freshly isolated human monocytes and the model human monocyte cell line, THP-1, to investigate changes in the expression of a panel of monocyte and macrophage markers during monocyte differentiation. We have examined these changes by RT-PCR and FACS analysis. Furthermore, we cloned the CCR2 promoter and analyzed specific changes in transcriptional activation of CCR2 during monocyte maturation.

Results

The CC chemokine receptor 2 (CCR2) is rapidly downregulated as monocytes move down the macrophage differentiation pathway while other related chemokine receptors are not. Using a variety of biochemical and transcriptional analyses in the human THP-1 monocyte model system, we show that both monocytes and THP-1 cells express high levels of CCR2, whereas THP-1 derived macrophages fail to express detectable CCR2 mRNA or protein. We further demonstrate that multiple signaling pathways activated by IFN-γ and M-CSF, or by protein kinase C and cytoplasmic calcium can mediate the downregulation of CCR2 but not CCR1.

Conclusion

During monocyte-to-macrophage differentiation CCR2, but not CCR1, is downregulated and this regulation occurs at the level of transcription through upstream 5' regulatory elements.

Alpha-chemokine receptors CXCR1-3 and their ligands in idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of neuromuscular disorders subdivided into polymyositis (PM), sporadic inclusion body myositis (sIBM) and dermatomyositis (DM). Chemokines play an essential role in sustained inflammation associated with IIM. We studied the distribution of the alpha-chemokine receptors CXCR1, 2, 3 and their ligands interferon-gamma (IFN-gamma)-inducible T cell alpha chemoattractant (I-TAC), IFN-gamma-inducible protein of 10 kDa (IP-10), monokine induced by IFN-gamma (MIG) and growth-related oncogene (GRO) in IIM using immunohistochemistry, immunofluorescence and Western blotting. Abundant expression of IP-10 was observed on macrophages and T cells surrounding and invading non-necrotic muscle fibers in PM and sIBM and in T cells in perimysial infiltrates of DM. IP-10 was also localized to blood vessel endothelial cells in all inflammatory and normal muscle tissues. The distribution of other alpha-chemokines was variable: Only low levels of MIG and I-TAC were detected; GRO was localized to the endomysial infiltrates of some PM and sIBM samples, but not in DM. Muscle tissues were invariably CXCR1 negative, while a subset of inflammatory cells in all IIM were CXCR2 positive. Strong CXCR3 expression was observed on the majority of T cells in each IIM. We describe the differential repertoire of alpha-chemokines in IIM, and offer additional proof of the predominance of Th1-driven reactions in the immunopathogenesis of all three diagnostic subgroups. We suggest the Th1-mediated immunity in general, and the CXCR3/IP-10 interaction in particular, as potential targets for novel therapeutic intervention in IIM.

Rheumatoid arthritis synovium contains plasmacytoid dendritic cells

We have previously described enrichment of antigen-presenting HLA-DR⁺ nuclear RelB⁺ dendritic cells (DCs) in rheumatoid arthritis (RA) synovium. CD123⁺HLA-DR⁺ plasmacytoid DCs (pDCs) and their precursors have been identified in human peripheral blood (PB), lymphoid tissue, and some inflamed tissues. We hypothesized recruitment of pDCs into the inflamed RA synovial environment and their contribution as antigen-presenting cells (APCs) and inflammatory cells in RA. CD11c⁺ myeloid DCs and CD123⁺ pDCs were compared in normal and RA PB, synovial fluid (SF), and synovial tissue by flow cytometry, immunohistochemistry, and electron microscopy and were sorted for functional studies. Nuclear RelB^-CD123⁺ DCs were located in perivascular regions of RA, in a similar frequency to nuclear RelB⁺CD123^- DCs, but not normal synovial tissue sublining. Apart from higher expression of HLA-DR, the numbers and phenotypes of SF pDCs were similar to those of normal PB pDCs. While the APC function of PB pDCs was less efficient than that of PB myeloid DCs, RA SF pDCs efficiently activated resting allogeneic PB T cells, and high levels of IFN-γ, IL-10, and tumor necrosis factor α were produced in response to incubation of allogeneic T cells with either type of SF DCs. Thus, pDCs are recruited to RA synovial tissue and comprise an APC population distinct from the previously described nuclear RelB⁺ synovial DCs. pDCs may contribute significantly to the local inflammatory environment.

Regulation of cellular and molecular trafficking across human brain endothelial cells by Th1- and Th2-polarized lymphocytes

We used adult human brain-derived endothelial cells (HBECs) to model migration of peripheral blood lymphocytes across the blood brain barrier (BBB) as occurs in MS. We demonstrate that enhanced expression of adhesion molecule ICAM-1 and production of chemokines CXCL10/IP-10, CCL2/MCP-1, and CXCL8/IL-8 by HBECs induced by supernatants derived from allogeneic or myelin basic protein-reactive Th1 cells is only partially reversed with anti-IFNgamma antibody. This effect is not reproduced with IFNgamma or TNFalpha alone, implicating the interaction of multiple factors in the overall functional response. Supernatants from Th2 cells neither suppressed nor amplified Th1-induced effects. Although both Th1 and Th2 supernatants modulated the expression and localization of tight junction molecules zonula occludens (ZO)-1 and ZO-2, neither supernatant altered the permeability of HBEC monolayers to albumin or increased subsequent T cell migration rates. Prior migration of Th1 or Th2 cells across HBECs did enhance subsequent passage of cells and soluble molecules. Our results suggest that initial infiltration of either Th1 or Th2 polarized lymphocytes across the BBB contributes to the continuation of an inflammatory response in the central nervous system.

Chemokines, chemokine receptors and adhesion molecules on different human endothelia: discriminating the tissue-specific functions that affect leucocyte migration

The selective accumulation of different leucocyte populations during inflammation is regulated by adhesion molecules and chemokines expressed by vascular endothelium. This study examined how chemokine production and the expression of adhesion molecules and chemokine receptors vary between endothelia from different vascular beds. Human saphenous vein endothelium was compared with lung and dermal microvascular endothelia and with umbilical vein endothelium and a bone-marrow endothelial cell line. All endothelia produced CCL2 and CXCL8 constitutively, whereas CXCL10 and CCL5 were only secreted after tumour necrosis factor (TNF)-alpha or interferon (IFN)-gamma stimulation. In combination with TNF-alpha, IFN-gamma suppressed CXCL8 but enhanced CCL5 and CXCL10, whereas transforming growth factor (TGF)-beta reduced secretion of all chemokines. Basal chemokine secretion was higher from umbilical vein than other endothelial cells. Chemokine receptors, CXCR1, CXCR3 and CCR3, were present on all endothelia but highest on saphenous vein. CCR4, CCR5, CCR6, CXCR2, CXCR4 and CXCR5 were also detected at variable levels on different endothelia. The variation between endothelia in chemokine secretion was much greater than the variations in adhesion molecules, both on resting cells and following cytokine stimulation. These results indicate that it is the tissue-specific variations in endothelial chemokine secretion rather than variations in adhesion molecules that can explain the different patterns of inflammation and leucocyte traffic seen in non-lymphoid tissues.

The relative activity of CXCR3 and CCR5 ligands in T lymphocyte migration: concordant and disparate activities in vitro and in vivo

In chronic inflammatory reactions such as rheumatoid arthritis and multiple sclerosis, T cells in the inflamed tissue express the chemokine receptors CXCR3 and CCR5, and the chemokine ligands (CCL) of these receptors are present in the inflammatory lesions. However, the contribution of these chemokines to T cell recruitment to sites of inflammation is unclear. In addition, the relative roles of the chemokines that bind CXCR3 (CXCL9, CXCL10, CXCL11) and CCR5 (CCL3, CCL4, CCL5) in this process are unknown. The in vitro chemotaxis and in vivo migration of antigen-activated T lymphoblasts and unactivated spleen T cells to chemokines were examined. T lymphoblasts migrated in vitro to CXCR3 ligands with a relative potency of CXCL10 > CXCL11 > CXCL9, but these cells demonstrated much less chemotaxis to the CCR5 ligands. In vivo, T lymphocytes were recruited in large numbers with rapid kinetics to skin sites injected with CXCL10 and CCL5 and less to CCL3, CCL4, CXCL9, and CXCL11. The combination of CCL5 with CXCL10 but not the other chemokines markedly increased recruitment. Coinjection of interferon-gamma, tumor necrosis factor alpha, and interleukin-1alpha to up-regulate endothelial cell adhesion molecule expression with CXCL10 or CCL5 induced an additive increase in lymphoblast migration. Thus, CXCR3 ligands are more chemotactic than CCR5 ligands in vitro; however, in vivo, CXCL10 and CCL5 have comparable T cell-recruiting activities to cutaneous sites and are more potent than the other CXCR3 and CCR5 chemokines. Therefore, in vitro chemotaxis induced by these chemokines is not necessarily predictive of their in vivo lymphocyte-recruiting activity.

Endothelial inflammation: the role of differential expression of N-deacetylase/N-sulphotransferase enzymes in alteration of the immunological properties of heparan sulphate

Heparan sulphate N-deacetylase/N-sulphotransferase (NDST) enzymes catalyse the reaction that initiates sulphation and subsequent modification of the oligosaccharide, heparan sulphate (HS). The extent and distribution of sulphate substitution on HS plays a vital role in regulation of the binding of a range of proteins, including IFN-gamma, several interleukins and most chemokines. In this study, the expression of NDST transcripts was found to be non-uniform between a range of cell types, suggesting that different cells produce characteristic HS species. It was found that stimulation of the HMEC-1 microvascular endothelial cell line with the pro-inflammatory cytokines IFN-gamma and TNF-alpha caused a transient decrease in the level of NDST-1 and -2 transcripts after 4 hours (P < 0.05 and P < 0.01 respectively), but the expression of NDST-1 increased above control levels after 16 hours (P < 0.01). The change in NDST expression was concurrent with an increase in the abundance of sulphated HS epitopes on the cell surface; this was not caused by variation in the expression of proteoglycans or by changes in the rate of GAG turnover. Cytokine-stimulated endothelial cells also showed an increase in their potential to bind RANTES (CCL5); this was abrogated by chlorate blockade of sulphotransferase activity or by heparitinase cleavage of cell surface HS. Monolayers of cytokine-stimulated HMEC-1 also supported an enhanced leukocyte chemotactic response towards RANTES. This study demonstrated that pro-inflammatory cytokines can increase NDST expression leading to increased sulphation of HS and a corresponding increase in sequestration of functional RANTES at the apical surface of endothelial cells. This may enhance leukocyte extravasation at sites of inflammation.

T-cell mediated induction of allogeneic endothelial cell chemokine expression

BACKGROUND

The goal of the current study was to test the ability of T cells to stimulate allogeneic endothelial cells to express chemokines, particularly the T-cell recruiting factors monokine induced by interferon-gamma (Mig) and inducible protein (IP)-10.

METHODS

Lymph node cells from C57BL/6 (H-2b) recipients of C3H (H-2k) skin grafts or from naïve mice were added to monolayers of C3H-derived endothelial cell line 2F-2B. After 5 or 24 hr, the lymph node cells were removed, and RNA was prepared from the endothelial cells and tested by ribonuclease protection assay or Northern blot hybridization for endothelial cell expression of chemokines.

RESULTS

Alloantigen-primed T cells induced endothelial cell expression of regulated on activation normal T-cell expressed and secreted (RANTES), IP-10, Mig, monocyte chemotactic protein-1, macrophage inflammatory protein-1alpha, and macrophage inflammatory protein-1beta within 5 hr of coculture. In vitro chemotaxis assays demonstrated the production of T-cell chemoattractants by the endothelial cells. With the exception of low levels of monocyte chemotactic protein-1 and RANTES, culture with naïve C57BL/6 lymph node T cells did not induce endothelial cell chemokine expression. Alloantigen-primed CD4 T cells induced endothelial expression of IP-10 and RANTES but none of the other chemokines tested, whereas primed CD8 T cells induced all of the chemokines tested. Expression of IP-10 and Mig was not induced when alloantigen-primed T cells from interferon-gamma deficient recipients of C3H skin grafts were cultured with the endothelial cells. This expression was blocked by addition of intercellular adhesion molecule-1 or lymphocyte function-associated antigen-1 specific antibodies to the cultures. CONCLUSIONS These results demonstrate the ability of alloantigen-primed CD8 T cells to quickly and directly stimulate endothelial cells to express and produce chemokines, including those recruiting T cells.

Alpha-melanocyte stimulating hormone prevents lipopolysaccharide-induced vasculitis by down-regulating endothelial cell adhesion molecule expression

The neuroendocrine hormone alpha-melanocyte stimulating hormone (MSH) has profound antiinflammatory and immunomodulating properties. Here we have examined the possibility that alpha-MSH may interfere with the expression and function of cell adhesion molecules (CAMs) expressed by human dermal microvascular endothelial cells (HDMECs) in response to lipopolysaccharide (LPS) or TNFalpha in vitro and in vivo. In HDMEC, alpha-MSH (10(-8)/10(-12) M) profoundly reduced the mRNA and protein expression of E-selectin, vascular CAM (VCAM)-1, and intercellular CAM (ICAM)-1 induced by LPS or TNFalpha as determined by semiquantitative RT-PCR, ELISA, and fluorescence-activated cell sorter analysis. In addition, alpha-MSH significantly impaired the LPS-induced ICAM-1 and VCAM-1-mediated adhesion of lymphocytes to HDMEC monolayer in a functional adhesion assay. Likewise, alpha-MSH effectively inhibited the transcription factor nuclear factor-kappaB activation in HDMEC, which is required for CAM gene expression. Importantly in vivo, in murine LPS-induced cutaneous vasculitis (local Shwartzman reaction), a single ip injection of alpha-MSH significantly suppressed the deleterious vascular damage and hemorrhage by inhibiting the sustained expression of vascular E-selectin and VCAM-1. This persistent expression has been implicated in the dysregulation of diapedesis and activation of leukocytes, which subsequently leads to hemorrhagic vascular damage. Our findings indicate that alpha-MSH may have an important therapeutical potential for the treatment of vasculitis, sepsis, and inflammatory diseases.

Gene expression profiles of microvascular endothelial cells after stimuli implicated in the pathogenesis of vasoocclusion

Altered gene expression in endothelial cells interacting with sickle red blood cells (RBC) and other blood components, in particular the pro-inflammatory cytokines, is an essential step in the pathogenesis of vasoocclusive crises in sickle cell disease (SCD). Using cDNA arrays, we monitored gene expression profiles of human lung microvascular endothelial cells (HMVEC-L) after stimuli that are likely involved in the pathogenesis of vasoocclusion. We detected increased expression of multiple genes in HMVEC-L after their exposure to pro-inflammatory cytokines TNFalpha and IL-1beta and to RBC with increased external exposure of phosphatidylserine and RBC from a patient with SC hemoglobin. While some of these genes have previously been implicated in vascular damage, many represent new targets for investigation of the pathogenesis of vasoocclusion in SCD.

Platelet-derived chemokines CXC chemokine ligand (CXCL)7, connective tissue-activating peptide III, and CXCL4 differentially affect and cross-regulate neutrophil adhesion and transendothelial migration

In this study, we have examined the major platelet-derived CXC chemokines connective tissue-activating peptide III (CTAP-III), its truncation product neutrophil-activating peptide 2 (CXC chemokine ligand 7 (CXCL7)), as well as the structurally related platelet factor 4 (CXCL4) for their impact on neutrophil adhesion to and transmigration through unstimulated vascular endothelium. Using monolayers of cultured HUVEC, we found all three chemokines to promote neutrophil adhesion, while only CXCL7 induced transmigration. Induction of cell adhesion following exposure to CTAP-III, a molecule to date described to lack neutrophil-stimulating capacity, depended on proteolytical conversion of the inactive chemokine into CXCL7 by neutrophils. This was evident from experiments in which inhibition of the CTAP-III-processing protease and simultaneous blockade of the CXCL7 high affinity receptor CXCR-2 led to complete abrogation of CTAP-III-mediated neutrophil adhesion. CXCL4 at substimulatory dosages modulated CTAP-III- as well as CXCL7-induced adhesion. Although cell adhesion following exposure to CTAP-III was drastically reduced, CXCL7-mediated adhesion underwent significant enhancement. Transendothelial migration of neutrophils in response to CXCL7 or IL-8 (CXCL8) was subject to modulation by CTAP-III, but not CXCL4, as seen by drastic desensitization of the migratory response of neutrophils pre-exposed to CTAP-III, which was paralleled by selective down-modulation of CXCR-2. Altogether our results demonstrate that there exist multiple interactions between platelet-derived chemokines in the regulation of neutrophil adhesion and transendothelial migration.

Reoxygenating microvascular endothelium exhibits temporal dissociation of NF-kappaB and AP-1 activation

Alterations of cellular redox balance in microvascular endothelium results in changes of essential cell functions. These alterations may arise, in part, due to modifications in the pattern of gene expression produced by transcription factor activation. Endothelium subjected to hypoxia/reoxygenation becomes redox imbalanced, thereby leading to activation and perhaps production of a proinflammatory state. A human dermal microvascular endothelial cell line (HMEC-1) was exposed to 6 h of hypoxia (3% O(2)) followed by return to normoxia atmospheric conditions. Reactive oxygen species (ROS) generation (dichlorofluoroscein epifluorescence) was immediate and significant following reoxygenation. Electrophoretic mobility shift assays revealed activation of the oxidant sensitive transcription factors NFkappaB and AP-1, though importantly, peak activation of each factor was separated temporally by greater than 60 min. NFkappaB activation occurred without degradation of the inhibitory protein IkappaBalpha. Reoxygenating HMEC-1 exhibited a greater than 500-fold increase in polymorphonuclear neutrophil (PMN) adhesion when compared to normoxic controls. Exposure of reoxygenating HMEC-1 to the antioxidant pyrrolidine dithiocarbamate produced complete abrogation of NFkappaB activation and the intensive PMN adhesion observed in untreated, posthypoxic HMEC-1. Though rexoygenation stress induced significant upregulation of PMN adhesion, no upregulation of interleukin-8 production was observed. Our results suggest that ROS generation occurring in endothelium following onset of reoxygenation stress signals activation of key transcription factors and that their activation takes place in a temporal fashion. The temporal feature of transcription factor activation may be key to production of a postischemic proinflammatory state.

Activation of m-calpain (calpain II) by epidermal growth factor is limited by protein kinase A phosphorylation of m-calpain

We have shown previously that the ELR-negative CXC chemokines interferon-inducible protein 10, monokine induced by gamma interferon, and platelet factor 4 inhibit epidermal growth factor (EGF)-induced m-calpain activation and thereby EGF-induced fibroblast cell motility (H. Shiraha, A. Glading, K. Gupta, and A. Wells, J. Cell Biol. 146:243-253, 1999). However, how this cross attenuation could be accomplished remained unknown since the molecular basis of physiological m-calpain regulation is unknown. As the initial operative attenuation signal from the CXCR3 receptor was cyclic AMP (cAMP), we verified that this second messenger blocked EGF-induced motility of fibroblasts (55% +/- 4.5% inhibition) by preventing rear release during active locomotion. EGF-induced calpain activation was inhibited by cAMP activation of protein kinase A (PKA), as the PKA inhibitors H-89 and Rp-8Br-cAMPS abrogated cAMP inhibition of both motility and calpain activation. We hypothesized that PKA might negatively modulate m-calpain in an unexpected manner by directly phosphorylating m-calpain. A mutant human large subunit of m-calpain was genetically engineered to negate a putative PKA consensus sequence in the regulatory domain III (ST369/370AA) and was expressed in NR6WT mouse fibroblasts to represent about 30% of total m-calpain in these cells. This construct was not phosphorylated by PKA in vitro while a wild-type construct was, providing proof of the principle that m-calpain can be directly phosphorylated by PKA at this site. cAMP suppressed EGF-induced calpain activity of cells overexpressing a control wild-type human m-calpain (83% +/- 3.7% inhibition) but only marginally suppressed that of cells expressing the PKA-resistant mutant human m-calpain (25% +/- 5.5% inhibition). The EGF-induced motility of the cells expressing the PKA-resistant mutant also was not inhibited by cAMP. Structural modeling revealed that new constraints resulting from phosphorylation at serine 369 would restrict domain movement and help "freeze" m-calpain in an inactive state. These data point to a novel mechanism of negative control of calpain activation, direct phosphorylation by PKA.

Expression of chemokine by human coronary-artery and umbilical-vein endothelial cells and its regulation by inflammatory cytokines

BACKGROUND

Activation of the endothelium is a critical event in the process of inflammation and is associated with the production of chemokines.

OBJECTIVE

To evaluate the proinflammatory cytokine-induced chemokine repertoire of human coronary-artery endothelial cells (HCAEC) both at the messenger RNA (mRNA) level and at protein level in direct comparison with that of human umbilical-vein endothelial cells (HUVEC).

METHODS

Human coronary-artery and human umbilical-vein endothelial cells were obtained commercially and experimental data were derived from cell cultures between passage levels 3 through 6. Supernatant fluids from cytokine [tumor necrosis factor-alpha (TNF-alpha), interleukin-1-alpha, and anti-TNF R55] stimulated endothelial cell cultures were used to study chemokine release. Sandwiched ELISA assays, obtained commercially, were used to estimate cell culture supernatant fluid levels of the selected chemokines: monocytic chemotactic protein-1, regulated upon activated normal T cells expressed and secreted, interleukin-8, transforming growth factor-beta-2 (TGF-beta2), and gamma interferon protein-10. Expression of messenger RNA was determined using selected labeled riboprobes (32P UTP) in a ribonuclease protection assay using total cellular mRNA.

RESULTS

Upon in-vitro stimulation with TNF-alpha and interleukin-1-alpha, production of regulated-upon-activated-normal-T-cells expressed and secreted (RANTES) protein by HCAEC was significantly increased relative to that by HUVEC, the greatest effect being found with interleukin-1-alpha. The opposite effect, however, was noted for levels of monocytic-chemotactic-protein-1 protein, which were detected in HUVEC at significantly higher levels than they were in HCAEC challenged by those cytokines. Production of gamma interferon-inducible protein-10 (gammaIP-10) by HUVEC was induced by TNF-alpha and interleukin-1-alpha, whereas only a modest induction by interleukin-1-alpha was seen in HCAEC. TGF-beta-2 protein was constitutively expressed in HCAEC but not in HUVEC. Expression of mRNA was analyzed by the ribonuclease-protectionassay. RANTES mRNA was expressed in HCAEC from 3 h through 48 h after treatment with TNF-alpha, whereas only a modest induction of RANTES was expressed in HUVEC 24 h and 48 h after treatment with TNF-alpha. Monocytic-chemotactic-protein-1 mRNA was constitutively expressed by both types of cell, but the basal levels in HCAEC was significantly higher than in HUVEC. HCAEC constitutively expressed both TGF-beta-1 and TGF-beta-2 mRNA, whereas HUVEC constitutively expressed TGF-beta-1 only.

CONCLUSION

Our data indicate that HCAEC and HUVEC express chemokines differently, which could contribute to or influence site-specific recruitment of subsets of leukocytes.

Homocysteine inhibits tumor necrosis factor-induced activation of endothelium via modulation of nuclear factor-kappa b activity

Homocystinuria is a metabolic disorder associated with an increased incidence of vascular disease. Here, we analyzed the effects of homocysteine on endothelial cell activation that is a prerequisite for the recruitment of leukocytes to sites of evolving atherosclerotic plaques. Exposure of human umbilical vein endothelial cells to homocysteine alone did not modulate expression of the adhesion molecules E-selectin, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, and the chemokines monocyte chemotactic protein-1 and interleukin-8. In contrast, tumor necrosis factor (TNF)-induced upregulation of these molecules was almost completely inhibited by homocysteine, but not by related thiol amino acids. Using electrophoretic mobility shift and reporter gene assays, the inhibitory effect of homocysteine could be attributed to inhibition of DNA binding and transcriptional activity of NF-kappa B. TNF-induced phosphorylation and degradation of I kappa B-alpha, however, were not affected. Neither was NF-kappa B-independent activation of endothelial cells by interferon-gamma influenced by homocysteine. In summary, our data indicate that homocysteine alters the response to injury of endothelial cells which may have fundamental impacts on mechanisms of leukocyte recruitment to sites of inflammation. Our findings might refer to a novel pathway by which homocysteine is involved in vascular disorders associated with homocystinuria.

Hantavirus infection induces the expression of RANTES and IP-10 without causing increased permeability in human lung microvascular endothelial cells

Sin Nombre virus (SNV) and Hantaan virus (HTN) infect endothelial cells and are associated with different patterns of increased vascular permeability during human disease. It is thought that such patterns of increased vascular permeability are a consequence of endothelial activation and subsequent dysfunction mediated by differential immune responses to hantavirus infection. In this study, the ability of hantavirus to directly induce activation of human lung microvascular endothelial cells (HMVEC-Ls) was examined. No virus-specific modulation in the constitutive or cytokine-induced expression of cellular adhesion molecules (CD40, CD54, CD61, CD62E, CD62P, CD106, and major histocompatibility complex classes I and II) or in cytokines and chemokines (eotaxin, tumor necrosis factor alpha, interleukin 1beta [IL-1beta], IL-6, IL-8, MCP-1, MIP-1alpha, and MIP-1beta) was detected at either the protein or message level in hantavirus-infected HMVEC-Ls. Furthermore, no virus-specific enhancement of paracellular or transcellular permeability or changes in the organization and distribution of endothelial intercellular junctional proteins was observed. However, infection with either HTN or SNV resulted in detectable levels of the chemokines RANTES and IP-10 (the 10-kDa interferon-inducible protein) in HMVEC-Ls within 72 h and was associated with nuclear translocation of interferon regulatory factor 3 (IRF-3) and IRF-7. Gamma interferon (IFN-gamma)-induced expression of RANTES and IP-10 could also be detected in uninfected HMVEC-Ls and was associated with nuclear translocation of IRF-1 and IRF-3. Treatment of hantavirus-infected HMVEC-Ls with IFN-gamma for 24 h resulted in a synergistic enhancement in the expression of both RANTES and IP-10 and was associated with nuclear translocation of IRF-1, IRF-3, IRF-7, and NF-kappaB p65. These results reveal a possible mechanism by which hantavirus infection and a TH1 immune response can cooperate to synergistically enhance chemokine expression by HMVEC-Ls and trigger immune-mediated increases in vascular permeability.

Dexamethasone affects cytokine-mediated adhesion of HL-60 human promyelocytic leukemia cells to cultured dermal microvascular endothelial cells

Leukocyte endothelial adhesion (LEA) is the prelude to a complex cascade of reactions following an immunological challenge. Recently, LEA has been implicated in the molecular basis of several dermatological disorders. While the role of proinflammatory cytokines, such as interleukin-1 beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), in LEA has been investigated using nondermal models, limited data exist regarding their effects on LEA in dermal models. This study shows that cotreatment of cultured human dermal endothelial cells (CADMEC) with IL-1beta and TNF-alpha resulted in a marked increase in the adherence of human promyelocytic leukemia (HL-60) cells to CADMEC and an increase in expression of intercellular adhesion molecule-1 and E-selectin. Pretreatment of CADMEC with dexamethasone, a long-lasting glucocorticoid, resulted in a decrease in both HL-60 cell adhesion to CADMEC and adhesion molecule expression. Taken together, these data demonstrate that LEA may play a role in inflammatory skin conditions and in the mechanisms underlying the potential use of glucocorticoids as a treatment option.

Non-small cell lung cancer cells induce monocytes to increase expression of angiogenic activity

Tumors are dependent on angiogenesis for survival and propagation. Accumulated evidence suggests that macrophages are a potentially important source of angiogenic factors in many disease states. However, the role(s) of macrophages in non-small cell lung cancer (NSCLC) have not been determined. We hypothesized that monocyte-derived macrophages are induced by NSCLC to increase expression of angiogenic factors. To define the role of macrophage-tumor cell interaction with respect to angiogenesis, human peripheral blood monocytes (PBM) were cocultured with A549 (human bronchoalveolar cell carcinoma) or Calu 6 (human anaplastic carcinoma) NSCLC cells. The resultant conditioned medium (CM) was evaluated for angiogenic potential and for expression of angiogenic factors. We found that endothelial cell chemotactic activity (as a measure of angiogenic potential) was significantly increased in response to CM from cocultures of PBM/NSCLC compared with PBM alone, NSCLC alone, or a combination of NSCLC and PBM CM generated separately. Subsequent analysis by ELISA reveals markedly increased CXC chemokine expression, with a lesser increase in vascular endothelial growth factor, in CM from PBM/NSCLC coculture. Neutralizing Ab to angiogenic CXC chemokines blocked the increase in endothelial cell chemotaxis. Furthermore, with separately generated CM as a stimulus, we found that macrophages are the predominant source of increased CXC chemokine expression. Finally, we found that NSCLC-derived macrophage migration-inhibitory factor is responsible for the increased expression of macrophage-derived angiogenic activity. These data suggest that the interaction between host macrophages and NSCLC cells synergistically increases angiogenic potential, and that this is due to an increased elaboration of angiogenic CXC chemokines.

Multiple signaling pathways regulate NF-kappaB-dependent transcription of the monocyte chemoattractant protein-1 gene in primary endothelial cells

The cytokine-induced C-C chemokine monocyte chemoattractant protein-1 (MCP-1) is an important regulator of leukocyte recruitment to sites of inflammatory challenge. Here, it is demonstrated that the widely distributed contact hapten NiCl(2), like tumor necrosis factor alpha (TNFalpha), induces monocyte-chemoattractant activity in primary human endothelial cells via induction of MCP-1. NiCl(2) rapidly activated mitogen-activated protein (MAP) kinase p38, and inhibition of p38 partially blocked NiCl(2)-induced MCP-1 messenger RNA and protein expression. Both NiCl(2)- and TNFalpha-induced MCP-1 synthesis was sensitive to D609, an inhibitor of phosphatidylcholine-dependent phospholipase C (PC-PLC). NiCl(2)-induced MCP-1 synthesis required activation of NF-kappaB since mutation of NF-kappaB-binding sites in the promoter resulted in complete loss of inducible promoter activity. Consistent with that finding, stimulation with NiCl(2) or TNFalpha activated IkappaB kinase-beta (IKKbeta), and transient transfection of dominant-negative IKKbeta strongly inhibited NiCl(2)- and TNFalpha-induced MCP-1 expression. However, D609 and the specific p38 inhibitor SB202190 did not affect NiCl(2)- and TNFalpha-induced IKKbeta activation, NF-kappaB DNA-binding activity, or transcriptional activity of a Gal4p65 fusion protein. This indicates that p38- and PC-PLC-dependent pathways directly regulate the transcriptional activity of NF-kappaB factors in the transcriptional complex. Consistent with that, inhibition of p38 blocked enhanced transcriptional activity induced by the transcriptional coactivator p300. Thus, it was concluded that at least 3 independent pathways regulate MCP-1 expression in endothelial cells. Its induction requires activation of the IKKbeta/IkappaBalpha/NF-kappaB signaling pathway, resulting in nuclear accumulation of p65 and subsequent recruitment of cofactors. Proper assembly and activity of this transcriptional complex is further modulated by the p38 MAP kinase cascade and a PC-PLC-dependent pathway.

Type 1/Type 2 immunity in infectious diseases

T helper type 1 (Th1) lymphocytes secrete secrete interleukin (IL)-2, interferon-gamma, and lymphotoxin-alpha and stimulate type 1 immunity, which is characterized by intense phagocytic activity. Conversely, Th2 cells secrete IL-4, IL-5, IL-9, IL-10, and IL-13 and stimulate type 2 immunity, which is characterized by high antibody titers. Type 1 and type 2 immunity are not strictly synonymous with cell-mediated and humoral immunity, because Th1 cells also stimulate moderate levels of antibody production, whereas Th2 cells actively suppress phagocytosis. For most infections, save those caused by large eukaryotic pathogens, type 1 immunity is protective, whereas type 2 responses assist with the resolution of cell-mediated inflammation. Severe systemic stress, immunosuppression, or overwhelming microbial inoculation causes the immune system to mount a type 2 response to an infection normally controlled by type 1 immunity. In such cases, administration of antimicrobial chemotherapy and exogenous cytokines restores systemic balance, which allows successful immune responses to clear the infection.