Signaling pathways regulating intercellular adhesion molecule 1 expression by endothelin 1: Comparison with interleukin-1β in normal and scleroderma dermal fibroblasts

Endothelium-specific endothelin-1 expression promotes pro-inflammatory macrophage activation by regulating miR-33/NR4A axis

The hallmark of atherogenesis is characterized as endothelial dysfunction and subsequent macrophage activation. Although our previous study has demonstrated that endothelin-1 (ET-1) plays an important role in atherogenesis, the underlying mechanism remains deeply investigation. Enhanced atherosclerotic plaques were observed in endothelium-specific ET-1 overexpression ApoE^-/- mice (eET-1/ApoE^-/-) concomitant with increased secretion of pro-inflammatory adhesion molecules and cytokines. The conditional media used for culturing human umbilical vein endothelial cells (HUVECs) with AdET-1 infection and subjected to OX-LDL stimulation, was collected and utilized for bone marrow-derived macrophages (BMDMs) culturing. RT-PCR analysis showed increased genes expression related to classical M1 macrophages but decreased alternative activated M2 macrophages genes expression in macrophage culturing with the conditional media. Furthermore, consistent regulations of macrophage polarization were observed using isolated exosomes from the conditional media. More importantly, we noticed that miR-33 was enriched in the exosomes derived by HUVECs with AdET-1 infection, while bioinformatics analysis further indicated that miR-33 directly targeted NR4A and miR-33/NR4A axis was required for the effect of endothelial-specific ET-1 overexpression on pro-inflammatory macrophage activation. By contrast, such effects could be reversed by ET-1 knockdown. Taken together, our study indicated that the exosomes derived by HUVECs with AdET-1 infection can transfer miR-33 to macrophages and subsequently promote pro-inflammatory macrophage activation by directly targeting to NR4A. These evidences clearly revealed that miR-33/NR4A axis was the important mechanism underlying the effect of ET-1 on macrophage activation and indicated that ET-1 may act as a promising target for atherosclerosis management.

PKC-Mediated Endothelin-1 Expression in Endothelial Cell Promotes Macrophage Activation in Atherogenesis

BACKGROUND

Atherosclerosis is a chronic inflammatory disease triggered by endothelial dysfunction and exaggerated by macrophage infiltration. Although endothelin-1 (ET-1) plays an important role in vascular inflammation and reactive oxygen species production, the individual effect of ET-1 in atherogenesis remains unclear.

METHODS AND RESULTS

ET-1 expression was increased in mouse atherosclerotic plaques and human umbilical vein endothelial cells (HUVECs) administrated by oxidized low-density lipoprotein stimulation. Moreover, the immunofluorescence co-staining showed upregulated ET-1 expression in endothelial cells. Real-time polymerase chain reaction demonstrated that ET-1 overexpression promoted adhesion molecules and chemokines secretion in HUVECs. Following this intervention, the migration of macrophages and the pro-inflammatory cytokines were increased. More importantly, the endothelial dysfunction regulated by ET-1 and subsequently the effect on macrophage activation were mediated by ETA receptor and largely reversed by protein kinase C (PKC) inhibitor. Eight-week-old male ApoE-/- mice and eET-1/ApoE-/- mice were fed with high-fat diet for 12 weeks. eET-1/ApoE-/- significantly increased atherosclerotic lesions in the whole aorta and aortic sinus, which accompanied by the induction of inflammatory cytokines and macrophages infiltration.

CONCLUSIONS

ET-1 accelerates atherogenesis by promoting adhesion molecules and chemokines, as well as subsequent macrophage activation. Collected, these evidence suggest that ET-1 might be a potential target for the treatment of atherogenesis.

Inhibitory Effects of Helianthus tuberosus Ethanol Extract on Dermatophagoides farina body-induced Atopic Dermatitis Mouse Model and Human Keratinocytes

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by complex symptoms. To treat AD without adverse effects, alternative therapeutic agents are required. The tubers of Helianthus tuberosus L. (Jerusalem artichoke) have been used in folk remedies for diabetes and rheumatism. However, its effect on AD development remains unknown. Therefore, this study examined the inhibitory effect of H. tuberosus (HT) on AD skin symptoms using an NC/Nga mouse model and HaCaT keratinocytes. The effect of HT and associated molecular mechanisms were evaluated in Dermatophagoides farina body (Dfb)-induced AD mice and tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated HaCaT keratinocytes by ELISA, western blot, and histological analysis. Topical HT administration attenuated AD skin symptoms in Dfb-induced AD mice, with a significant reduction in the dermatitis score and production of inflammatory mediators. HT also decreased epidermal thickness and mast cell infiltration. Moreover, HT restored filaggrin expression and inhibited adhesion molecules in the mice. These effects were confirmed in vitro. Furthermore, HT suppressed the activation of NF-κB, Akt, and mitogen-activated protein kinase (MAPK) signaling pathways induced by TNF-α/IFN-γ. These results suggest that HT is a potential therapeutic agent or supplement for skin allergic inflammatory diseases such as AD.

Genetic susceptibility of five tagSNPs in the endothelin-1 (EDN1) gene to coronary artery disease in a Chinese Han population

Endothelin-1 (ET-1) plays important roles in endothelial dysfunction, vascular physiology, inflammation, and atherosclerosis. Nonetheless, the role of ET-1 (EDN1) gene variants on coronary artery disease (CAD) risk remains poorly understood. The aim of the present study was to evaluate the role of EDN1 gene polymorphisms on individual susceptibility to CAD. We genotyped five tagSNPs (single-nucleotide polymorphisms) (rs6458155, rs4145451, rs9369217, rs3087459, and rs2070699) within EDN1 gene in 525 CAD patients and 675 control subjects. In a multivariate logistic regression analysis, we detected an association of rs6458155 in EDN1 gene with the CAD risk; compared with the TT homozygotes, the CT heterozygotes (odds ratio (OR) = 1.53, 95% confidence interval (CI) = 1.02–2.29, P=0.040) and the CC homozygotes (OR = 1.55, 95% CI = 1.01–2.36, P=0.043) were statistically significantly associated with the increased risk for CAD. A similar trend of the association was found in dominant model (OR = 1.53, 95% CI = 1.05–2.25, P=0.029). Consistently, the haplotype rs6458155C-rs4145451C containing rs6458155 C allele exhibited the increased CAD risk (OR = 1.22, 95% CI = 1.03–1.43, and P=0.018). In addition, CT genotype of rs6458155 conferred the increased plasma ET-1 levels compared with TT genotype (P<0.05). No association of the other four tagSNPs in EDN1 gene with CAD risk was observed. In conclusion, our study provides the first evidence that EDN1 tagSNP rs6458155 is associated with CAD risk in the Chinese Han population, which is probably due to the influence of the circulating ET-1 levels.

Getting out of a sticky situation: targeting the myofibroblast in scleroderma

There is no treatment for the fibrosis observed in scleroderma (systemic sclerosis, SSc). Although genome-wide expression profiling has suggested that differences in gene expression patters between non-lesional and lesional skin are minimal, phenotypically these areas of tissue are quite different. In fact, lesional areas of scleroderma patients can be distinguished by the presence of a differentiated form of fibroblast, termed the myofibroblast. This cell type expresses the highly contractile protein α-smooth muscle actin (α-SMA). Fibroblasts isolated from SSc lesions excessively synthesize, adhere to and contract extracellular matrix (ECM) and display activated adhesive signaling pathways. Strategies aimed at blocking myofibroblast differentiation, persistence and activity are therefore likely to be useful in alleviating the fibrosis in scleroderma.

Endothelin receptor selectivity: evidence from in vitro and pre-clinical models of scleroderma

Scleroderma [systemic sclerosis (SSc)] is a spectrum of connective tissue diseases characterized by micro- and macro-vasculopathy, inflammation and autoimmunity and tissue remodelling that often leads to excessive scarring and fibrosis in both interstitial and vascular compartments. Pre-clinical investigations and gene association studies have led to improved understanding of the cell and molecular mechanisms underlying disease pathogenesis and to the identification of key molecular candidates that may represent potentially useful disease biomarkers and effective therapeutic targets. Studies on the endothelin (ET) system, pre-dominantly ET-1 and the cell surface receptors [type A (ET(A))] and type B (ET(B))], have provided evidence for an important role of this system in the vascular and fibrotic pathologies in SSc. To date, promising clinical results, utilizing dual/mixed ET receptor antagonism have been obtained in two of the vascular complications associated with SSc, ischaemic digital ulceration and pulmonary arterial hypertension. Evidence suggests that ET-1 is able to activate and re-program the functional phenotypes of vascular smooth muscle cells, microvascular pericytes and tissue fibroblasts into pro-fibrogenic cell populations with myofibroblasts-like properties. The impact of receptor-selective, over mixed-receptor, antagonism has also been studied in vitro with respect to cell differentiation and proliferation, extracellular matrix synthesis, production and deposition and in pathological cellular contraction. However, the complexity of the ET system, potential for receptor cross-talk, interactions with down-stream signal transduction cascades, as well as the potent inter-relationships with other important ligand-receptor pathways have made in vivo studies difficult to unravel. Moreover, little information is available on the role of the ET system and receptor selectivity in the recruitment and activation of mesenchymal progenitor cells in tissue remodelling and fibrosis or on the early inflammatory response. Here, we discuss the available pre-clinical evidence for the role of the ET system in tissue repair, scarring and fibrosis, using the connective tissue diseases SSc and model systems of fibrogenesis.

The role of ET(A) and ET(B) receptor antagonists in acute and allergic inflammation in mice

In this study, we investigated the effects of the selective ET(A) (BQ-123) and ET(B) (BQ-788) receptor antagonists for endothelin-1 (ET-1) against several flogistic agent-induced paw edema formation and ovalbumin-induced allergic lung inflammation in mice. The intraplantar injection of BQ-123, but not BQ-788, significantly inhibited carrageenan-, PAF-, ET-1- and bradykinin-induced paw edema formation. The obtained inhibitions (1h after the inflammatory stimulus) were 79+/-5%, 55+/-4%, 55+/-6% and 74+/-4%, respectively. In carrageenan-induced paw edema, the mean ID(50) value for BQ-123 was 0.77 (0.27-2.23)nmol/paw. The neutrophil influx induced by carrageenan or PAF was reduced by BQ-123, with inhibitions of 55+/-2% and 72+/-4%, respectively. BQ-123 also inhibited the indirect macrophage influx induced by carrageenan (55+/-6%). However, BQ-788 failed to block the cell influx caused by either of these flogistic agents. When assessed in the bronchoalveolar lavage fluid in a murine model of asthma, both BQ-123 and BQ-788 significantly inhibited ovalbumin-induced eosinophil recruitment (78+/-6% and 71+/-8%), respectively. Neither neutrophil nor mononuclear cell counts were significantly affected by these drugs. Our findings indicate that ET(A), but not ET(B), selective ET-1 antagonists are capable of preventing the acute inflammatory responses induced by carrageenan, PAF, BK and ET-1. However, both ET(A) and ET(B) receptor antagonists were found to be effective in inhibiting the allergic response in a murine model of asthma.

Significance of microparticles in progressive systemic sclerosis with interstitial pneumonia

We measured and compared the levels of microparticles, chemokines, cell adhesion molecules and platelet activation markers with a view to developing a better understanding of their potential contributions to the pathophysiology of progressive systemic sclerosis (PSS, scleroderma). The concentrations of all the factors in PSS patients were significantly higher than those in normal subjects. PSS patients were divided to two groups by whether they have interstitial pneumonia (IP) or not. There were no differences in the levels of soluble(s) VCAM-1, sICAM-1, sE-selectin and IL-8 between the two groups. However, there were significant between-group differences in the levels of sP-selectin, sCD40L, ENA-78, RANTES (regulated on activation normally T-cell expressed and secreted), platelet-derived microparticles (PDMPs), monocyte-derived microparticle (MDMPs) and KL-6. The level of tissue factor expression on monocytes by A23187 stimulation in PSS patients was found to be similar to that in healthy controls. Although PDMP did not induce the expression of tissue factor on monocytic cell line (THP-1) directly, the recombinant sCD40 ligand-induced expression of tissue factor on THP-1 and generation of MDMP from this cell line were enhanced by the addition of PDMPs. Our findings suggested that elevated levels of PDMPs and MDMPs may be interpreted as a sign of vascular complications in PSS patients, particularly those complicated with IP, offering a new treatment strategy in these patients.

Elevated serum levels of intercellular adhesion molecule ICAM-1 in Pseudoxanthoma elasticum

BACKGROUND

Pseudoxanthoma elasticum (PXE, OMIM 177850 and 264800) is a rare heritable disorder predominantly affecting the skin, the eyes and the vascular system. The disease is caused by mutations in the ABCC6 gene and is characterized by calcification and extracellular matrix remodeling, including alterations of the vessel walls. Here, we investigated the cell adhesion molecules ICAM-1 in PXE patients.

METHODS

Soluble ICAM-1 was determined in 58 non-consanguineous PXE patients by quantitative sandwich enzyme immunoassay. The allelic frequencies of the ICAM-1 variant p.K469E were analyzed in patients and age- and sex-matched controls.

RESULTS

Soluble ICAM-1 levels were significantly elevated in male and female PXE patients (p<0.02 and p<0.001, respectively). In addition, the ICAM-1 concentration correlated with the ABCC6 gene status of the PXE patients. The ICAM variant p.K469E genotypes were not different in PXE patients and age- and sex-matched controls.

CONCLUSIONS

Our data show for the first time increased ICAM-1 concentrations in PXE patients, potentially due to the chronic oxidative stress and elevated protease activity followed by extracellular matrix remodeling which have been previously observed in PXE patients.

Bosentan regulates the expression of adhesion molecules on circulating T cells and serum soluble adhesion molecules in systemic sclerosis-associated pulmonary arterial hypertension

Objectives:

To study the expression of adhesion molecules in patients with systemic sclerosis (SSc) with and without pulmonary arterial hypertension (PAH) and the effects of therapy with the endothelin-1 (ET-1) receptor antagonist, bosentan.

Methods:

In all, 35 patients with SSc and 25 healthy donors (HD) were selected for this study. Of 35 patients, 10 had isolated PAH assessed by Doppler echocardiography and treated with bosentan. Peripheral blood (PB) lymphocytes were isolated by density gradient centrifugation, and the expression of lymphocyte function-associated antigen-1 (LFA-1), very late antigen-4 (VLA-4) and L-selectin on CD3 T cells was assessed by double immunofluorescence and flow-cytometry. As endothelial activation markers, serum soluble P-selectin, platelet/endothelial cell adhesion molecule (PECAM)-1, vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1 and von Willebrand factor (vWF) antigen were assessed by ELISA. In patients with SSc-PAH, T cell subsets and soluble endothelial markers were assessed at baseline and after 6 and 12 months of bosentan therapy.

Results:

In patients with SSc-PAH, serum soluble ICAM-1, VCAM-1, P-selectin and PECAM-1 levels were higher than in HD at baseline and fell to normal values after 12 months of bosentan therapy. CD3–LFA1 T cells were significantly higher in PAH-SSc at baseline than in HD or SSc and significantly decreased after therapy. CD3–L-selectin T cells were significantly lower in SSc-PAH at baseline than in HD or SSc and rose to normal levels after bosentan therapy.

Conclusions:

This study confirms that endothelial activation occurs in SSc, and suggests that changes in the T cell/endothelium interplay take place in SSc-associated PAH. Bosentan seems to be able to hamper these changes and restore T cell functions in these patients.

How does endothelial cell injury start? The role of endothelin in systemic sclerosis

A considerable amount of research time has been invested in studies aimed at elucidating pathogenic processes in systemic sclerosis (SSc). Despite this, major challenges for biomedical science remain, such as identification of the key factors that determine susceptibility to SSc, and elucidation of the precise nature of the initiating event that causes endothelial cell injury and ultimately brings about the biological cascade(s) that lead to the pathologic vascular changes. Involved factors are likely to include genetic perturbations, environmental cues, tissue injury, infection and hypoxia/oxidative stress. As important as determining the initiating events are the identification and characterization of key factors that are functionally important in driving vascular disease progression, because these factors are potential targets for therapeutic intervention. This article reviews the role of endothelin as an example of a pleiotropic mediator with effects on various aspects of SSc pathogenesis, such as inflammation, vasculopathy and tissue remodelling.