Shear stress-induced shedding of soluble intercellular adhesion molecule-1 from saphenous vein endothelium

Rapid Assessment of Biomarkers on Single Extracellular Vesicles Using 'Catch and Display' on Ultrathin Nanoporous Silicon Nitride Membranes

Extracellular vesicles (EVs) are particles secreted by all cells that carry bioactive cargo and facilitate intercellular communication with roles in normal physiology and disease pathogenesis. EVs have tremendous diagnostic and therapeutic potential and accordingly, the EV field has grown exponentially in recent years. Bulk assays lack the sensitivity to detect rare EV subsets relevant to disease, and while single EV analysis techniques remedy this, they are undermined by complicated detection schemes often coupled with prohibitive instrumentation. To address these issues, we propose a microfluidic technique for EV characterization called 'catch and display for liquid biopsy (CAD-LB)'. CAD-LB rapidly captures fluorescently labeled EVs in the similarly-sized pores of an ultrathin silicon nitride membrane. Minimally processed sample is introduced via pipette injection into a simple microfluidic device which is directly imaged using fluorescence microscopy for a rapid assessment of EV number and biomarker colocalization. In this work, nanoparticles were first used to define the accuracy and dynamic range for counting and colocalization by CAD-LB. Following this, the same assessments were made for purified EVs and for unpurified EVs in plasma. Biomarker detection was validated using CD9 in which Western blot analysis confirmed that CAD-LB faithfully recapitulated differing expression levels among samples. We further verified that CAD-LB captured the known increase in EV-associated ICAM-1 following the cytokine stimulation of endothelial cells. Finally, to demonstrate CAD-LB's clinical potential, we show that EV biomarkers indicative of immunotherapy responsiveness are successfully detected in the plasma of bladder cancer patients undergoing immune checkpoint blockade.

Mechanical regulation of the early stages of angiogenesis

Favouring or thwarting the development of a vascular network is essential in fields as diverse as oncology, cardiovascular disease or tissue engineering. As a result, understanding and controlling angiogenesis has become a major scientific challenge. Mechanical factors play a fundamental role in angiogenesis and can potentially be exploited for optimizing the architecture of the resulting vascular network. Largely focusing on in vitro systems but also supported by some in vivo evidence, the aim of this Highlight Review is dual. First, we describe the current knowledge with particular focus on the effects of fluid and solid mechanical stimuli on the early stages of the angiogenic process, most notably the destabilization of existing vessels and the initiation and elongation of new vessels. Second, we explore inherent difficulties in the field and propose future perspectives on the use of in vitro and physics-based modelling to overcome these difficulties.

Hesperidin Functions as an Ergogenic Aid by Increasing Endothelial Function and Decreasing Exercise-Induced Oxidative Stress and Inflammation, Thereby Contributing to Improved Exercise Performance

The regulation of blood flow to peripheral muscles is crucial for proper skeletal muscle functioning and exercise performance. During exercise, increased mitochondrial oxidative phosphorylation leads to increased electron leakage and consequently induces an increase in ROS formation, contributing to DNA, lipid, and protein damage. Moreover, exercise may increase blood- and intramuscular inflammatory factors leading to a deterioration in endurance performance. The aim of this review is to investigate the potential mechanisms through which the polyphenol hesperidin could lead to enhanced exercise performance, namely improved endothelial function, reduced exercise-induced oxidative stress, and inflammation. We selected in vivo RCTs, animal studies, and in vitro studies in which hesperidin, its aglycone form hesperetin, hesperetin-metabolites, or orange juice are supplemented at any dosage and where the parameters related to endothelial function, oxidative stress, and/or inflammation have been measured. The results collected in this review show that hesperidin improves endothelial function (via increased NO availability), inhibits ROS production, decreases production and plasma levels of pro-inflammatory markers, and improves anaerobic exercise outcomes (e.g., power, speed, energy). For elite and recreational athletes, hesperidin could be used as an ergogenic aid to enhance muscle recovery between training sessions, optimize oxygen and nutrient supplies to the muscles, and improve anaerobic performance.

Local Injection of Hydroxyapatite Electret Ameliorated Infarct Size After Myocardial Infarction

Background: Previous studies showed that hydroxyapatite electret (HAE) accelerates the regeneration of vascular endothelial cells and angiogenesis. This study investigated the effects of HAE in myocardial infarction (MI) model mice.

Methods and Results: MI was induced in mice by ligating the left anterior descending artery. Immediately after ligation, HAE, non-polarized hydroxyapatite (HAN), or water (control) was injected into the infarct border myocardium. Functional and histological analyses were performed 2 weeks later. Echocardiography revealed that HAE injection preserved left ventricular systolic function and the wall thickness of the scar, whereas HAN-injected mice had impaired cardiac function and thinning of the wall, similar to control mice. Histological assessment showed that HAE injection significantly attenuated the length of the scar lesion. There was significant accumulation of CD31-positive cells and increased expression of vascular endothelial growth factor (Vegf), intercellular adhesion molecule-1 (Icam1), vascular cell adhesion molecule-1 (Vcam1), hypoxia-inducible factor-1α (Hif1a), and C-X-C motif chemokine ligand 12 (Cxcl12) genes in the infarct border zone of HAE-injected mice. These effects were not induced by HAN injection. Anti-VEGFR2 antibody canceled the beneficial effect of HAE. In vitro experiments in a human cardiovascular endothelial cell line showed that HAE dose-dependently increased VEGFA expression.

Conclusions: Local injection of HAE attenuated infarct size and improved cardiac function after MI, probably due to angiogenesis. The electric charge of HAE may stimulate angiogenesis via HIF1α-CXCL12/VEGF signaling.

Placental syncytiotrophoblast extracellular vesicles enter primary endothelial cells through clathrin-mediated endocytosis

INTRODUCTION

The aim was to investigate syncytiotrophoblast extracellular vesicle (STBEV) uptake mechanisms by primary endothelial cells, the effects on gene expression, cell activation as well as the effect of aspirin.

METHODS

The STBEVs were derived using the placental perfusion system, from normal or preeclamptic placentas. Endothelial uptake was analysed with flow cytometry. To elucidate uptake, different inhibitors were tested; Cytochalasin D, Chlorpromazine hydrochloride, Methyl-B-cyclodextrin, Dynasore and Wortmannin. Endothelial gene expression was evaluated using an endothelial cell biology qPCR array. Cell activation was studied by ICAM-1 surface expression after STBEV exposure, with and without aspirin treatment.

RESULTS

Normal and preeclamptic STBEV uptake was blocked in similar ways. Chlorpromazine, Dynasore and Wortmannin almost completely blocked STBEV uptake. Methyl-B-cyclodextrin blocked 45-60% of the uptake while Cytochalasin D did not block uptake at all. Neither normal nor preeclamptic STBEVs had any significant effects on endothelial gene expression. Normal STBEVs down-regulated cell surface protein ICAM-1 expression, with and without aspirin treatment. Aspirin had no effect on STBEV uptake or cellular gene expression on its own, however it down regulated ICAM-1 protein expression in combination with preeclamptic STBEV exposure.

DISCUSSION

STBEV uptake primarily occurred through clathrin-mediated endocytosis. The STBEVs had no significant effect on gene expression but did have effects on ICAM-1 surface expression. The prophylactic mechanisms of aspirin may be by preventing the endothelium from being activated by the preeclamptic STBEVs.

The protective activity of mesothelial cells against peritoneal growth of gastrointestinal tumors: The role of soluble ICAM-1

In this project we examined how the presence of human peritoneal mesothelial cells (HPMCs) modifies (supports or inhibits) colorectal and pancreatic cancer cell progression in mice peritoneal cavity. Experiments were performed using primary, omentum-derived HPMCs, commercially available colorectal (SW-480) and pancreatic (PSN-1) cancer cells, and immunocompromised SCID mice. Tumor growth within the peritoneal cavity was monitored using bioluminescence. Adhesion of the cancer cells to HPMCs was examined using a fluorescence-based method, while the incidence of apoptosis was quantified using flow cytometry. Experiments showed that SW480 and PSN-1 cells formed tumors in vivo at higher efficiency when they were injected alone than in the presence of HPMCs. In vitro investigations confirmed that firm adhesion of SW480 and PSN-1 cells to HPMCs is mediated by interactions between ICAM-1 and CD43. They also revealed that IL-6 and TNFα up-regulate the expression of cell-bound ICAM-1 and the secretion of soluble ICAM-1 (sICAM-1). The basal release of sICAM-1 by HPMCs positively correlated with the expression of the cell-bound molecule. sICAM-1 inhibited dose-dependently the adhesion of SW480 and PSN-1 cells to HPMCs. Cancer cells that did not adhere to HPMCs displayed increased activity of caspase-3 and -9, increased incidence of apoptosis, and an inability to re-adhesion, as compared with their intact counterparts not exposed to sICAM-1. Our findings indicate that under certain conditions HPMCs are capable of inhibiting growth of gastrointestinal tumors in a mechanism involving the anti-adhesive capabilities of sICAM-1.

Adipokines and soluble cell adhesion molecules in insulin resistant and non-insulin resistant women with polycystic ovary syndrome

INTRODUCTION

Insulin resistance (IR) is closely associated with increased atherogenic risk.

OBJECTIVE

To investigate leptin, adiponectin, soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) levels and their relationship with each other and metabolic parameters in women with polycystic ovary syndrome (PCOS).

METHODS

The study included 76 PCOS women divided into insulin resistant and non-insulin resistant. Anthropometric parameters, glucose and lipid parameters, leptin, adiponectin, sICAM-1 and sVCAM-1 were determined. Homeostasis model of IR index(HOMA-IR), atherogenic index of plasma(AIP) and leptin/adiponectin ratio were calculated. HOMA-IR > 2.5 and/or fasting plasma glucose/immunoreactive insulin ratio < 0.333 were used as markers for IR.

RESULTS

Non-insulin resistant PCOS had significantly higher adiponectin and sVCAM-1 levels. AIP was significantly higher in insulin resistant PCOS. Adiponectin showed a positive correlation with sVCAM-1 and sICAM-1.

CONCLUSION

Insulin resistant PCOS women were at higher atherogenic risk compared to non-insulin resistant group. sVCAM-1 data confirms the necessity of further investigations for clarifying its role in IR.

Secondhand smoke exposure and endothelial stress in children and adolescents

OBJECTIVE

Links between secondhand smoke exposure and cardiovascular disease in adults are well established. Little is known about the impact of this exposure on cardiovascular status during childhood. The purpose of this study was to investigate relationships between secondhand smoke exposure in children and adolescents and cardiovascular disease risk--systemic inflammation, endothelial stress, and endothelial repair.

METHODS

A total of 145 subjects, aged 9 to 18 years, were studied. Tobacco smoke exposure was determined by hair nicotine level. Cardiovascular risk was assessed by markers of systemic inflammation (C-reactive protein [CRP] and adiponectin); by soluble intercellular adhesion molecule 1 (s-ICAM1), which measures endothelial activation after surface vascular injury; and by endothelial repair. This was measured by prevalence of endothelial progenitor cells (EPCs), which are bone marrow-derived cells that home preferentially to sites of vascular damage.

RESULTS

Hair nicotine was directly correlated with s-ICAM1 (r = 0.4090, P < .0001) and negatively correlated with EPC prevalence (r = -0.2002, P = .0195). There was no relationship between hair nicotine and CRP, and a trend toward a weak relationship with adiponectin. Hair nicotine and body mass index were independent variables in a multivariate model predicting s-ICAM1; hair nicotine was the only significant variable in a model predicting EPC prevalence.

CONCLUSIONS

Secondhand smoke exposure during childhood and adolescence is detrimental to vascular health because s-ICAM1 is a marker for endothelial activation and stress after vascular surface injury, and EPCs contribute to vascular repair. The fact that body mass index is also a factor in the model predicting s-ICAM1 is concerning, in that 2 risk factors may both contribute to endothelial stress.

Tumor necrosis factor α-mediated restructuring of the Sertoli cell barrier in vitro involves matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule-1 (ICAM-1) and the actin cytoskeleton

The mammalian blood-testis barrier (BTB) restructures throughout spermatogenesis, thereby allowing developing germ cells to enter the adluminal compartment of the seminiferous epithelium. Previous studies have shown pro-inflammatory cytokines such as tumor necrosis factor α (TNFα) and interleukin-1α to be important regulators of Sertoli cell barrier/BTB function in vitro and in vivo. In this study, the effects of TNFα on Sertoli cell barrier function were assessed, with emphasis on changes in proteases and cell adhesion molecules following treatment. By immunoblotting and immunohistochemistry, MMP9 was found to be present in germ cells, localizing by and large to spermatocytes and spermatids in the adult rat testis. Following treatment of Sertoli cells with physiologically relevant consecutive doses of recombinant human TNFα (25 ng/ml), the steady-state levels of active-matrix metalloprotease 9 (MMP9), membrane-bound intercellular adhesion molecule (mICAM-1) and androgen receptor increased significantly. TNFα also downregulated the steady-state level of occludin, in agreement with earlier results that showed TNFα to disrupt Sertoli cell barrier/BTB function. In addition, TNFα affected the filamentous actin cytoskeleton in Sertoli cells, which appeared to be mediated by cortactin, a regulator of actin dynamics. Taken collectively, these findings imply that germ cells may be involved in BTB restructuring via the localized production of TNFα. These results also illustrate that barrier restructuring correlated with an increase in Sertoli cell mICAM-1, suggesting that it may be critical for adhesion as germ cells traverse the “opened” BTB.

Circulating matrix metalloproteinase patterns in association with aortic dilatation in bicuspid aortic valve patients with isolated severe aortic stenosis

Bicuspid aortic valve (BAV) exhibits a clinical incline toward aortopathy, in which aberrant tensile and shear stress generated by BAV can induce differential expression of matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs). Whether stenotic BAV, which exhibits additional eccentric high-velocity flow jet upon ascending aorta and further worsens circumferential systolic wall shear stress than BAV with echocardiographically normal aortic valve, can lead to unique plasma MMP/TIMP patterns is still unknown. According to their valvulopathy and aortic dilatation status, 93 BAV patients were included in the present study. Group A (n = 37) and B (n = 28) comprised severely stenotic patients with or without ascending aorta dilatation; Group C (n = 12) and D (n = 16) comprised echocardiographically normal BAV patients with or without ascending aorta dilatation. Plasma MMP/TIMP levels (MMP-1, -2, -3, -8, -9, -10, -13 and TIMP-1, -2, -4) were determined via a multiplex ELISA detection system in a single procedure. Among patients with isolated severe aortic stenosis, plasma levels of MMP-2 and -9 were significantly elevated when ascending aortic dilatation was present (p = 0.001 and p = 0.002, respectively). MMP-2, however, remained as the single elevated plasma component among echocardiographically normal BAV patients with dilated ascending aorta (p = 0.027). Multivariate analysis revealed that MMP-2 and MMP-9 could both serve as independent risk factor for aortic dilatation in the case of isolated severe stenosis (p = 0.003 and p = 0.001, respectively), and MMP-2 in echocardiographically normal patients (p = 0.002). In conclusion, BAV patients with isolated severe aortic stenosis demonstrated a distinct plasma MMP/TIMP pattern, which might be utilized as circulating biomarkers for early detection of aortic dilatation.

Soluble adhesion molecules as markers for sepsis and the potential pathophysiological discrepancy in neonates, children and adults

Sepsis is a severe and life-threatening systemic inflammatory response to infection that affects all populations and age groups. The pathophysiology of sepsis is associated with aberrant interaction between leukocytes and the vascular endothelium. As inflammation progresses, the adhesion molecules that mediate these interactions become shed from cell surfaces and accumulate in the blood as soluble isoforms that are being explored as potential prognostic disease biomarkers. We critically review the studies that have tested the predictive value of soluble adhesion molecules in sepsis pathophysiology with emphasis on age, as well as the underlying mechanisms and potential roles for inflammatory shedding. Five soluble adhesion molecules are associated with sepsis, specifically, E-selectin, L-selectin and P-selectin, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. While increased levels of these soluble adhesion molecules generally correlate well with the presence of sepsis, their degree of elevation is still poorly predictive of sepsis severity scores, outcome and mortality. Separate analyses of neonates, children and adults demonstrate significant age-dependent discrepancies in both basal and septic levels of circulating soluble adhesion molecules. Additionally, a range of both clinical and experimental studies suggests protective roles for adhesion molecule shedding that raise important questions about whether these should positively or negatively correlate with mortality. In conclusion, while predictive properties of soluble adhesion molecules have been researched intensively, their levels are still poorly predictive of sepsis outcome and mortality. We propose two novel directions for improving clinical utility of soluble adhesion molecules: the combined simultaneous analysis of levels of adhesion molecules and their sheddases; and taking age-related discrepancies into account. Further attention to these issues may provide better understanding of sepsis pathophysiology and increase the usefulness of soluble adhesion molecules as diagnostic and predictive biomarkers.

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

Since its original identification as a leukocyte gelatinase/type V collagenase and tumour type IV collagenase, gelatinase B/matrix metalloproteinase (MMP)-9 is now recognised as playing a central role in many aspects of tumour progression. In this review, we relate current concepts concerning the many ways in which gelatinase B/MMP-9 influences tumour biology. Following a brief outline of the gelatinase B/MMP-9 gene and protein, we analyse the role(s) of gelatinase B/MMP-9 in different phases of the tumorigenic process, and compare the importance of gelatinase B/MMP-9 source in the carcinogenic process. What becomes apparent is the importance of inflammatory cell-derived gelatinase B/MMP-9 in tumour promotion, early progression and triggering of the "angiogenic switch", the integral relationship between inflammatory, stromal and tumour components with respect to gelatinase B/MMP-9 production and activation, and the fundamental role for gelatinase B/MMP-9 in the formation and maintenance of tumour stem cell and metastatic niches. It is also apparent that gelatinase B/MMP-9 plays important tumour suppressing functions, producing endogenous angiogenesis inhibitors, promoting inflammatory anti-tumour activity, and inducing apoptosis. The fundamental roles of gelatinase B/MMP-9 in cancer biology underpins the need for specific therapeutic inhibitors of gelatinase B/MMP-9 function, the use of which must take into account and substitute for tumour-suppressing gelatinase B/MMP-9 activity and also limit inhibition of physiological gelatinase B/MMP-9 function.

Intercellular adhesion molecule 1: recent findings and new concepts involved in mammalian spermatogenesis

Spermatogenesis, the process of spermatozoa production, is regulated by several endocrine factors, including testosterone, follicle stimulating hormone, luteinizing hormone and estradiol 17β. For spermatogenesis to reach completion, developing germ cells must traverse the seminiferous epithelium while remaining transiently attached to Sertoli cells. If germ cell adhesion were to be compromised for a period of time longer than usual, germ cells would slough from the seminiferous epithelium and infertility would result. Presently, Sertoli-germ cell adhesion is known to be mediated largely by classical and desmosomal cadherins. More recent studies, however, have begun to expand long-standing concepts and to examine the roles of other proteins such as intercellular adhesion molecules. In this review, we focus on the biology of intercellular adhesion molecules in the mammalian testis, hoping that this information is useful in the design of future studies.

Different expression pattern of serum soluble intercellular adhesion molecules-1 and neutrophilic expression of CD18 in patients with diabetic retinopathy

AIM

To investigate the levels of serum soluble intercellular adhesion molecules-1(sICAM-1) and neutrophilic expression of CD18 in patients with various stages of diabetic retinopathy and to determine their different expression pattern in the development of diabetic retinopathy(DR).

METHODS

Levels of serum sICAM-1 and CD18 on the surface of neutrophile were measured in 41 DR patients, they were classified in three subgroups according to the stage of retinopathy as determined by fund's ophthalmoscopy; 10 control subjects were also studied. sICAM-1 were measured by enzyme-linked immunosorbent assay and CD18 by flow cytometry.

RESULTS

The neutrophilic CD18 expression and serum sICAM-1 level were all significantly elevated in all diabetic subgroups compared to control subjects (P<0.01). The differences of CD18 and sICAM-1 among the diabetic subgroups were significant in CD18 but not in sICAM-1. The progression of retinopathy was associated with an increase both in CD18 and in sICAM-1 levels by simple correlation analysis (β=0.74, P<0.001; β=0.38, P<0.01, respectively). But stepwise multiple regression analysis revealed that only CD18 was independent determinant of retinopathy (β=1.04, P<0.01).

CONCLUSION

Our results confirm the contribution of endothelial and neutrophilic activation in the development of DR as indicated by increased levels of CD18 and sICAM-1. However, a direct implication of CD18 and ICAM-1 in the progression of DR can be supported only in the CD18 but not ICAM-1. CD18 and ICAM-1 may play different role in the development of diabetic retinopathy.

Pathologic shear triggers shedding of vascular receptors: a novel mechanism for down-regulation of platelet glycoprotein VI in stenosed coronary vessels

Ligand-induced ectodomain shedding of glycoprotein VI (GPVI) is a metalloproteinase-dependent event. We examined whether shear force, in the absence of GPVI ligand, was sufficient to induce shedding of GPVI. Human-citrated platelet-rich plasma or washed platelets were subjected to increasing shear rates in a cone-plate viscometer, and levels of intact and cleaved GPVI were examined by Western blot and ELISA. Pathophysiologic shear rates (3000-10 000 seconds(-1)) induced platelet aggregation and metalloproteinase-dependent appearance of soluble GPVI ectodomain, and GPVI platelet remnant. Shedding of GPVI continued after transient exposure to shear. Blockade of α(IIb)β(3), GPIbα, or intracellular signaling inhibited shear-induced platelet aggregation but minimally affected shear-induced shedding of GPVI. Shear-induced GPVI shedding also occurred in platelet-rich plasma or washed platelets isolated from a von Willebrand disease type 3 patient with no detectable VWF, implying that shear-induced activation of platelet metalloproteinases can occur in the absence of GPVI and GPIbα ligands. Significantly elevated levels of sGPVI were observed in 10 patients with stable angina pectoris, with well-defined single vessel coronary artery disease and mean intracoronary shear estimates at 2935 seconds(-1) (peak shear, 19 224 seconds(-1)). Loss of GPVI in platelets exposed to shear has potential implications for the stability of a forming thrombus at arterial shear rates.

Synergistic Regulation of Angiogenic Sprouting by Biochemical Factors and Wall Shear Stress

The process of sprouting angiogenesis involves activating endothelial cells in a quiescent monolayer of an existing vessel to degrade and migrate into the underlying matrix to form new blood vessels. While the roles of biochemical factors in angiogenic sprouting have been well characterized, the roles of fluid forces have received much less attention. This review summarizes results that support a role for wall shear stress in post-capillary venules as a mechanical factor capable of synergizing with biochemical factors to stimulate pro-angiogenic signaling in endothelial cells and promote sprout formation.

How do immune cells overcome the blood-brain barrier in multiple sclerosis?

The presence of the blood-brain barrier (BBB) restricts the movement of soluble mediators and leukocytes from the periphery to the central nervous system (CNS). Leukocyte entry into the CNS is nonetheless an early event in multiple sclerosis (MS), an inflammatory disorder of the CNS. Whether BBB dysfunction precedes immune cell infiltration or is the consequence of perivascular leukocyte accumulation remains enigmatic, but leukocyte migration modifies BBB permeability. Immune cells of MS subjects express inflammatory cytokines, reactive oxygen species (ROS) and enzymes that can facilitate their migration to the CNS by influencing BBB function, either directly or indirectly. In this review, we describe how immune cells from the peripheral blood overcome the BBB and promote CNS inflammation in MS through BBB disruption.

Secretome of human endothelial cells under shear stress

Endothelial cells are exposed to different types of shear stress which triggers the secretion of subsets of proteins. In this study, we analyzed the secretome of endothelial cells under static, laminar, and oscillatory flow. To differentiate between endogenously expressed and added proteins, isolated human umbilical vein endothelial cells were labeled with l-Lysine-(13)C(6),(15)N(2) and l-Arginine-(13)C(6),(15)N(4). Shear stress was applied for 24 h using a cone-and-plate viscometer. Proteins from the supernatants were isolated, trypsinized, and finally analyzed using LC-MS/MS (LTQ). Under static control condition 395 proteins could be identified, of which 78 proteins were assigned to the secretome according to Swiss-Prot database. Under laminar shear stress conditions, 327 proteins (83 secreted) and under oscillatory shear stress 507 proteins (79 secreted) were measured. We were able to identify 6 proteins specific for control conditions, 8 proteins specific for laminar shear stress, and 5 proteins specific for oscillatory shear stress. In addition, we identified flow-specific secretion patterns like the increased secretion of cell adhesion proteins and of proteins involved in protein binding. In conclusion, the identification of shear stress specific secreted proteins (101 under different flow conditions) emphasizes the role of endothelial cells in modulating the plasma composition according to the physiological requirements.

Elevated sICAM-1 levels in patients with hemorrhagic fever with renal syndrome caused by Hantaan virus

Increased vascular permeability and vascular leakage are characteristic pathological changes in hemorrhagic fever with renal syndrome (HFRS). Vascular endothelial cells are the main targets of Hantaan virus, the etiological agent of the severe form of HFRS. Hantaan virus can induce extensive damage of small blood vessels and capillaries. In vitro infection of human umbilical vein endothelial cells by Hantaan virus can induce the expression of intercellular adhesion molecule-1 (ICAM-1). The involvement of this molecule is implied in human HFRS. In the present study, serum-soluble ICAM-1 (sICAM-1) levels were determined and their relationships with the clinical course and disease severity were investigated in 112 HFRS patients and 30 healthy controls. The results showed that the serum levels of sICAM-1 in HFRS patients at fever, hypotensive, oliguric, and polyuric phases were significantly higher than those in controls (p < 0.001). However, no significant differences between the serum concentrations of sICAM-1 in the milder and more severe groups of patients were observed (p > 0.05). It is suggested that sICAM-1 was involved in the progression of HFRS. Time-dependent determinations of sICAM-1 levels may be indicators for the progression of disease, and elevated levels of sICAM-1 were not suggested to be correlated to disease severity.

Endothelial nitric oxide deficiency reduces MMP-13-mediated cleavage of ICAM-1 in vascular endothelium: a role in atherosclerosis

OBJECTIVE

Lack of endothelial nitric oxide synthase worsens atherosclerosis at least by increasing monocyte adhesion to endothelial cells. The purpose of this study was to elucidate the molecular mechanism elicited by NO.

METHODS AND RESULTS

We evaluated atherosclerosis in apoE and NOS3/apoE-deficient mice fed with high-cholesterol diet. We found significant increase in aortic lesion size, and infiltration of macrophages in NOS3/apoE-null mice when compared to apoE-deficient animals. To test the relevance of cellular adhesion as well as extracellular matrix degradation, we evaluated ICAM-1, VCAM-1, PECAM-1, MMP-2, MMP-9, MMP-12, MT1-MMP, and MMP-13 levels in mouse aortas. Lack of NO inhibits MMP-13 and increases ICAM-1 levels in atherosclerosis as compared to apoE-null mice. Ectopically expression of ICAM-1 in eukaryotic cells revealed that extracellular domain of ICAM-1 harbors a substrate recognized by MMP-13. Incubation of COS-7 cells expressing ectopic ICAM-1 in the presence of active MMP-13 induced inhibition of RAW 264.7 cell adhesion to COS-7 monolayers. MALDI-TOF MS analysis combined to Liquid chromatography coupled to Ion Trap MS on ICAM-1 incubated with MMP-13 allowed us to determine the cleavage sites of MMP-13 at positions E61 and G98 of ICAM-1. G98 is part of a PDGQS moiety, which shows homology with the consensus PDGLS substrate located at the MMP-13 cleaved site of type II collagen I-alpha.

CONCLUSIONS

Taking together, these results point toward MMP-13 as a mechanism for the NO-mediated protection of atherosclerosis.

Femoral artery remodeling after aerobic exercise training without weight loss in women

Background

It is currently unclear whether reductions in adiposity mediate the improvements in vascular health that occur with aerobic exercise. The purpose of this longitudinal study of 13 healthy women (33 ± 4 years old) was to determine whether 14 weeks of aerobic exercise would alter functional measures of vascular health, namely resting aortic pulse wave velocity (aPWV, an index of arterial stiffness), femoral artery diameter (D_FA), and femoral artery blood flow (BF_FA) independent of changes in adiposity.

Methods

Aerobic fitness was assessed as VO₂peak normalized to fat-free mass, and adiposity (percent body fat) was determined by dual energy x-ray absorptiometry. Serum concentrations of proteins associated with risk for cardiovascular disease, including C-reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), and leptin, were also measured. Subjects cycled for 50 minutes, 3 times per week.

Results

Aerobic fitness normalized to fat-free mass increased 6% (P = 0.03) whereas adiposity did not change. Resting D_FA increased 12% (P < 0.001) and resting shear rate decreased 28% (P = 0.007). Aortic PWV, and serum sICAM-1, CRP and leptin did not change with training.

Conclusion

Significant reductions in adiposity were not necessary for aerobic exercise training to bring about improvements in aerobic fitness and arterial remodeling. Peripheral arterial remodeling occurred without changes in central arterial stiffness or markers of inflammation.

Potentiation of NK cell-mediated cytotoxicity in human lung adenocarcinoma: role of NKG2D-dependent pathway

Natural cytotoxicity receptors and NKG2D correspond to major activating receptors involved in triggering of tumor cell lysis by human NK cells. In this report, we investigated the expression of NKG2D ligands (NKG2DLs), MHC class I-related chain (MIC) A, MICB and UL16-binding proteins 1, 2 and 3, on a panel of human non-small-cell lung carcinoma cell lines, and we analyzed their role in tumor cell susceptibility to NK cell lysis. Although adenocarcinoma (ADC) cells expressed heterogeneous levels of NKG2DLs, they were often resistant to NK cell-mediated killing. Resistance of a selected cell line, ADC-Coco, to allogeneic polyclonal NK cells and autologous NK cell clones correlated with shedding of NKG2DLs resulting from a matrix metalloproteinase (MMP) production. Treatment of ADC-Coco cells with a MMP inhibitor (MMPI) combined with IL-15 stimulation of autologous NK cell clones lead to a potentiation of NK cell-mediated cytotoxicity. This lysis is mainly NKG2D mediated, since it is abrogated by anti-NKG2D-neutralizing mAb. These results suggest that MMPIs, in combination with IL-15, may be useful for overcoming tumor cell escape from the innate immune response.

Soluble ICAM-1 and VCAM-1 as markers of endothelial activation

Activated endothelium releases the soluble adhesion molecules vascular cell adhesion molecule-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1). Measurement of fluid-phase adhesion molecules is therefore used to quantify endothelial activation, but it is unclear which is the better marker. The aims of the study were to compare the relationships between mRNA, surface and total expression and released VCAM-1 and ICAM-1 in endothelial cell cultures during activation, and to compare human umbilical vein endothelial cells (HUVEC) with the microvascular cell line HMEC-1. sVCAM-1 better represented mRNA and surface expression changes in HUVEC undergoing endotoxin stimulation than did sICAM-1. Very little VCAM-1 was released from endotoxin-stimulated HMEC-1, and sICAM-1 seemed a better activation marker for these cells. During incubation of HUVEC in media with glucose concentrations of 5.6, 10.6 or 20.6 mM, VCAM-1 was released to the media in a dose-dependent way without changes in surface expression. ICAM-1 was not influenced by the glucose concentration. There are situations when VCAM-1 concentrations in the media do not mirror the surface expression on HUVEC in culture, indicating that measurements of soluble adhesion molecules may not necessarily be representative of the conditions on the cell surface. Endothelium from different locations showed varying responses with respect to VCAM-1 and ICAM-1 liberation upon endotoxin stimulation. Thus, both sVCAM-1 and sICAM-1 should be quantified in clinical studies of endothelial activation until their characteristics are better clarified.

The potential anti-inflammatory benefits of improving physical fitness in hypertension

Hypertension is associated with an increased risk of stroke and atherosclerosis. In addition to elevated blood pressure, hypertension is characterized by neuroendocrine and immune activation, including elevated levels of C-reactive protein, inflammatory cytokines, and soluble adhesion molecules, which are predictive of morbidity and mortality outcomes. Pharmacological treatment for hypertension reduces blood pressure, but has limited effectiveness in reducing the accompanying inflammation and its associated morbidity and mortality. Exercise and diet interventions regularly show reductions in blood pressure in hypertensive individuals. Similar interventions in other populations show reductions in many inflammatory markers, but these effects have not been routinely examined in hypertensive individuals. The mechanisms through which exercise might exert an anti-inflammatory action include the sympathetic nervous system, the hypothalamic-pituitary-adrenal axis, as well as direct effects of blood pressure. Here, exercise is promoted as a potentially effective treatment for both the elevated blood pressure and chronic inflammation found in hypertension.

The biochemical, biological, and pathological kaleidoscope of cell surface substrates processed by matrix metalloproteinases

Matrix metalloproteinases (MMPs) constitute a family of more than 20 endopeptidases. Identification of specific matrix and non-matrix components as MMP substrates showed that, aside from their initial role as extracellular matrix modifiers, MMPs play significant roles in highly complex processes such as the regulation of cell behavior, cell-cell communication, and tumor progression. Thanks to the comprehensive examination of the expanded MMP action radius, the initial view of proteases acting in the soluble phase has evolved into a kaleidoscope of proteolytic reactions connected to the cell surface. Important classes of cell surface molecules include adhesion molecules, mediators of apoptosis, receptors, chemokines, cytokines, growth factors, proteases, intercellular junction proteins, and structural molecules. Proteolysis of cell surface proteins by MMPs may have extremely diverse biological implications, ranging from maturation and activation, to inactivation or degradation of substrates. In this way, modification of membrane-associated proteins by MMPs is crucial for communication between cells and the extracellular milieu, and determines cell fate and the integrity of tissues. Hence, insights into the processing of cell surface proteins by MMPs and the concomitant effects on physiological processes as well as on disease onset and evolution, leads the way to innovative therapeutic approaches for cancer, as well as degenerative and inflammatory diseases.

Impact of diabetic serum on endothelial cells: an in-vitro-analysis of endothelial dysfunction in diabetes mellitus type 2

Diabetic endothelial dysfunction was characterized by altered levels of adhesion molecules and cytokines. Aim of our study was to evaluate the effects of diabetic serum on cell-growth and proinflammatory markers in human saphenous vein endothelial cells (HSVEC) from diabetic and non-diabetic patients. Diabetic serum showed (1) complementary proliferative activity for non-diabetic and diabetic HSVEC, (2) unchanged surface expression of adhesion molecules, and (3) elevated levels of sICAM-1 in HSVEC of all donors. The concentration of sVCAM-1 was increased only in diabetic cells. The proinflammatory state of diabetic HSVEC characterized by increased levels of cytokines was compensated. We concluded that even under normoglycemic conditions the serum itself contains critical factors leading to abnormal regulation of inflammation in diabetics. We introduced an in vitro model of diabetes representing the endothelial situation at the beginning of diabetes (non-diabetic cells/diabetic serum) as well as the diabetic chronic state (diabetic cells/diabetic serum).

Inverse correlation between coronary blood flow velocity and sICAM-1 level observed in ischemic heart disease patients

Systemic factors and blood flow velocity related to atherosclerosis have been examined mainly separately or by in vitro studies. The aim of our study was to investigate the association between local coronary blood flow (corrected TIMI frame count, CTFC) and systemic atherosclerosis-related inflammatory parameters such as soluble intercellular adhesion molecule-1 (sICAM-1), interleukin-6 (Il-6), high sensitivity C-reactive protein (hsCRP) and von Willebrand factor (vWF) in humans. We enrolled the following groups of ischemic heart disease (IHD) patients: patients with coronary stenosis and stable (CAD, n = 96) or unstable angina (ACS, n = 27), patients with documented myocardial ischemia and normal coronary angiogram (NEG, n = 68). Patient groups showed only marginal differences in CTFC or sICAM-1 levels. In contrast, when IHD patients were studied individually, general positive correlation was found between CTFC and sICAM-1 level (r = 0.33; in NEG r = 0.25; in CAD r = 0.37; in ACS r = 0.61), being the strongest in ACS. The relation was independent from age, gender, BMI, smoking, hypertension, diabetes, previous myocardial infarction, family history of IHD, medication, hsCRP, IL-6 and vWF levels. (odds ratio, OR = 6.4; CI 95%: 2.43-16.84; p < 0.05). Nevertheless, correlation between CTFC and IL-6, hsCRP, vWF levels was not found. These results indicate inverse correlation between coronary blood flow and adhesion molecule production independently from conventional cardiovascular risk factors and inflammatory markers.

Inflammation dampened by gelatinase A cleavage of monocyte chemoattractant protein-3

Tissue degradation by the matrix metalloproteinase gelatinase A is pivotal to inflammation and metastases. Recognizing the catalytic importance of substrate-binding exosites outside the catalytic domain, we screened for extracellular substrates using the gelatinase A hemopexin domain as bait in the yeast two-hybrid system. Monocyte chemoattractant protein-3 (MCP-3) was identified as a physiological substrate of gelatinase A. Cleaved MCP-3 binds to CC-chemokine receptors-1, -2, and -3, but no longer induces calcium fluxes or promotes chemotaxis, and instead acts as a general chemokine antagonist that dampens inflammation. This suggests that matrix metalloproteinases are both effectors and regulators of the inflammatory response.