Human monoclonal anti-endothelial cell IgG-derived from a systemic lupus erythematosus patient binds and activates human endothelium in vitro

Neuropsychiatric lupus erythematosus: Focusing on autoantibodies

Patients with systemic lupus erythematosus (SLE) frequently suffer from nervous system complications, termed neuropsychiatric lupus erythematosus (NPLE). NPLE accounts for the poor prognosis of SLE. Correct attribution of NP events to SLE is the primary principle in managing NPLE. The vascular injuries and neuroinflammation are the fundamental neuropathologic changes in NPLE. Specific autoantibody-mediated central nerve system (CNS) damages distinguish NPLE from other CNS disorders. Though the central antibodies in NPLE are generally thought to be raised from the periphery immune system, they may be produced in the meninges and choroid plexus. On this basis, abnormal activation of microglia and disease-associated microglia (DAM) should be the common mechanisms of NPLE and other CNS disturbances. Improved understanding of both characteristic and sharing features of NPLE might yield further options for managing this disease.

Circulating platelet aggregates damage endothelial cells in culture

BACKGROUND

Presence of circulating endothelial cells (CECs) in systemic circulation may be an indicator of endothelial damage and/or denudation, and the body's response to repair and revascularization. Thus, we hypothesized that aggregated platelets (AgPlts) can disrupt/denude the endothelium and contribute to the presence of CEC and EC-derived particles (ECDP).

METHODS

Endothelial cells were grown in glass tubes and tagged with/without 0.5 μm fluorescent beads. These glass tubes were connected to a mini-pump variable-flow system to study the effect of circulating AgPlts on the endothelium. ECs in glass tube were exposed to medium alone, nonaggregated platelets (NAgPlts), AgPlts, and 90 micron polystyrene beads at a flow rate of 20 mL/min for various intervals. Collected effluents were cultured for 72 h to analyze the growth potential of dislodged but intact ECs. Endothelial damage was assessed by real time polymerase chain reaction (RT-PCR) for inflammatory genes and Western blot analysis for von Willebrand factor.

RESULTS AND CONCLUSION

No ECs and ECDP were observed in effluents collected after injecting medium alone and NAgPlts, whereas AgPlts and Polybeads drastically dislodged ECs, releasing ECs and ECDP in effluents as the time increased. Effluents collected when endothelial cell damage was seen showed increased presence of von Willebrand factor as compared to control effluents. Furthermore, we analyzed the presence of ECs and ECDPs in heart failure subjects, as well as animal plasma samples. Our study demonstrates that circulating AgPlts denude the endothelium and release ECs and ECDP. Direct mechanical disruption and shear stress caused by circulating AgPlts could be the underlying mechanism of the observed endothelium damage.

Association of eNOS gene polymorphisms and systemic lupus erythematosus in southeast Iran

BACKGROUND AND OBJECTIVES

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with unknown etiology. Genetic and environmental factors play important roles in the pathogenesis of SLE. The primary objective of this study was to investigate the possible association of eNOS gene intron 4b/a, Glu298Asp and T-786C polymorphisms with SLE in southeast Iran populations.

PATIENTS AND METHODS

This was a case-control study comparing eNOS polymorphisms in 106 SLE patients and 196 age- and sex-matched healthy controls. The 4b/a, Glu298Asp and T-786C polymorphisms were analyzed using polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

Our findings indicated that the 4b/a polymorphism was associated with SLE, and the risk of SLE was 3.5- and 1.75-fold higher in patients with aa and ba genotypes than in patients with bb genotype. No association was observed between Glu298Asp and T-786C polymorphisms and SLE. There were no differences in eNOS gene polymorphisms between the Balouch and Fars population.

CONCLUSION

Statistically significant differences were observed in genotypes and allele frequencies of 4b/a polymorphism between patients with SLE and healthy controls in southeast Iran.

Circulating endothelial cells as a marker of vascular dysfunction in patients with systemic lupus erythematosus by real-time polymerase chain reaction

CONTEXT

Systemic lupus erythematosus (SLE) is associated with an increased risk of atherosclerosis; endothelial dysfunction represents the first step in its pathogenesis.

OBJECTIVE

To assess endothelial dysfunction in SLE by circulating endothelial cells (CECs) and to characterize SLE-specific factors that contribute to its appearance.

DESIGN

Case-control study was conducted on 60 subjects, divided into 2 groups: group A (30 patients with SLE) and group B (30 healthy sex- and age-matched controls). Total cholesterol, triglycerides, antinuclear antibodies, anti-double-stranded DNA antibodies, and C3 were determined in all patients. Systemic lupus erythematosus activity was assessed using the SLE Disease Activity Index. Endothelial function was assessed by means of flow-mediated dilation of the brachial artery using B-mode ultrasonography and relative quantification of CD 146 mRNA by real-time polymerase chain reaction.

RESULTS

The group of SLE patients was formed of 20 females and 10 males, with a mean age of 31.16 ± 9.69 years. The values of SLE-specific tests and SLE Disease Activity Index were represented by anti-double-stranded DNA antibodies 160 ± 40.5, C3 68.91 ± 11.91 mg/dL, total cholesterol 188.66 ± 49.63 mg/dL, triglycerides 143.41 ± 46.26 mg/dL, and SLE Disease Activity Index 12.66 ± 3.70. Values for flow-mediated dilation were 8.85% ± 2.02% (group A) and 20.33% ± 6.19% (group B), P < .001, and CECs were 300 ± 40.5 μL⁻¹ blood (group A) and 10 ± 2.5 μL⁻¹ blood (group B). The statistical analysis showed a strong inverse correlation between CECs and SLE Disease Activity Index, a strong correlation between CECs and C3, a strong correlation between CECs and anti-double-stranded DNA antibodies, and a moderate inverse correlation between CECs and total cholesterol.

CONCLUSION

Endothelial dysfunction is present in SLE patients even in the absence of traditional cardiovascular risk factors due to disease activity.

The altered expression of inflammation-related molecules and secretion of IL-6 and IL-8 by HUVEC from newborns with maternal inactive systemic lupus erythematosus is modified by estrogens

Systemic lupus erythematosus (SLE) predominantly affects women, especially those in reproductive age. Genetic contributions to disease susceptibility as well as immune dysregulation, particularly persistent inflammatory responses, are considered essential features. Our aim was to determine whether human umbilical vein endothelial cells (HUVEC) isolated from healthy newborns to women with inactive SLE show inflammation-related abnormalities that might lead to an early development of SLE in the offsprings. HUVEC isolated from six women with inactive SLE were stimulated with 2.5 ng/mL of TNF-alpha and/or physiological and pharmacological doses of 17-I(2) estradiol (E2). Then the expression of VCAM-1, ICAM-1, E-selectin, toll-like receptor-9 (TLR-9), heat shock protein 70 (HSP70) and HSP90 were measured. The concentrations of IL-6, IL-8, and IL-10 were also determined in maternal serum and in TNF-alpha stimulated and non-stimulated HUVEC culture supernatant. HUVEC from children with no family history of autoimmune disease served as controls. Our results showed that in HUVEC from SLE+ mothers, a constitutively low expression of adhesion molecules was enhanced by TNF-alpha treatment. The E2 (1 ng/mL) increased the expression of adhesion molecules but had no effect upon TNF-alpha-treated cells. IL-6 was constitutively higher in SLE+ HUVEC, whereas IL-8 was lower; E2 treatment diminished the latter. The E2 had no effect upon IL-6 and IL-8 secretions in TNF-alpha-treated cells. SLE+ HUVEC showed a disordered cytoskeleton and overexpressed HSP70, HSP90, and TLR-9. Our results indicate that endothelial cells of newborns to SLE+ mothers are in a proinflammatory condition which can be upregulated by estrogens.

Common inflammatory mediators orchestrate pathophysiological processes in rheumatoid arthritis and atherosclerosis

RA is characterized by a systemic inflammatory state, in which immune cells and soluble mediators play a crucial role. These inflammatory processes resemble those in other chronic inflammatory diseases, such as atherosclerosis. The chronic systemic inflammation in RA can be considered as an independent risk factor for the development of atherosclerosis, and represents an important field to investigate the reasons of the increase of acute cardiovascular events in RA. In the present review, we focused on several mediators of autoimmunity, inflammation and endothelial dysfunction, which can be considered the most promising targets to prevent atherogenesis in RA. Among several mediators, the pro-inflammatory cytokine TNF-alpha has been shown as a crucial factor to induce atherosclerosis in RA patients.

Von Willebrand factor, red cell fragmentation, and disease activity in systemic lupus erythematosus

This study sought to determine whether the plasma levels of Von Willebrand factor (vWf) and the degree of red blood cell (RBC) fragmentation on peripheral smear correlate with disease activity in systemic lupus erythematosus (SLE). Forty consecutive patients who fulfilled the criteria for SLE were studied prospectively for 1 year. Patients were categorized according to the SLE Disease Activity Index (SLEDAI) as either active (>2) or inactive disease and followed up monthly (active) or quarterly (inactive). At each visit, patients were examined fully and had complete blood count, tests on antibodies to double-stranded DNA, C3, and C4 levels, and urinalysis. Citrated plasma was analyzed for vWf antigen by standard enzyme-linked immunosorbent assay. A Wright's stained blood smear was obtained and schistocytes were quantitated on blood smear. The number of schistocytes per 500 RBCs was determined and a schistocyte index (SI) was calculated. At baseline, vWf correlated with SLEDAI (r = 0.64, p < 0.01), SI correlated with SLEDAI (r = 0.62, p < 0.01), and vWf and SI correlated with each other (r = 0.41, p = 0.01). There was an inverse correlation between baseline C3 levels and vWf (r = 0.49, p = 0.0013) and C3 levels and SI (r = 0.40, p = 0.01). Over time, there was also a correlation of SLEDAI with vWf (r = 0.53, p = 0.002) and SI (r = 0.57;p = 0.002). The relation of vWf with SI approached but did not reach statistical significance (r = 0.37, p = 0.06). We found that the plasma levels of vWf and the degree of RBC fragmentation correlate with lupus disease activity over time. Therefore, inflammation in SLE may be associated with endothelial injury.

Pathogenic mechanisms of anti-endothelial cell antibodies (AECA): their prevalence and clinical relevance

Anti‐endothelial cell antibodies (AECA) represent a heterogeneous family of autoantibodies directed against structural endothelial proteins, as well as antigens adhering to endothelial cells. Although AECA immunoassays still show a high‐interlaboratory variability, several findings suggest a pathogenic role of these autoantibodies in diseases characterized by endothelial damage. In this chapter, we analyze the knowledge about AECA prevalence, clinical relevance, and their pathogenic role in autoimmune diseases focusing in particular on systemic lupus erythematosus, antiphospholipid syndrome, systemic sclerosis (SSc), and systemic vasculitis.

Mouse monoclonal anti-human thrombomodulin antibodies bind to and activate endothelial cells through NF-kappaB activation in vitro

OBJECTIVE

To clarify whether mouse monoclonal antibodies (mAb) against human thrombomodulin (TM), which react with human TM present on the endothelial cell (EC) surface, have anti-endothelial cell antibody (AECA) activity and influence antiinflammatory properties of human TM expressed on the EC surface in vitro.

METHODS

Three preparations of mouse mAb against human TM that react with different sites of the human TM epidermal growth factor-like domain were tested for their ability to 1) bind to ECs, 2) modulate cytokine secretion from ECs, EC adhesion molecule expression, and neutrophil adhesion to ECs, and 3) stimulate nuclear translocation of NF-kappaB through the degradation of cytoplasmic IkappaB in ECs. Recombinant human interleukin-1beta (IL-1beta) was used as a positive control, and mouse IgG1 and mouse IgG2a were used as negative controls.

RESULTS

The 3 preparations of mouse mAb against human TM that bind to unfixed EC monolayers enhanced IL-6 and IL-8 secretion from ECs, up-regulated expression of endothelial leukocyte adhesion molecule 1, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 on EC monolayers, and enhanced neutrophil adhesion to ECs to a degree similar to that observed with IL-1beta stimulation, but they did not induce the secretion of tumor necrosis factor alpha or IL-1beta from ECs throughout the incubation period. The 3 preparations stimulated nuclear translocation of NF-kappaB through the degradation of cytoplasmic IkappaB. Mouse IgG1 and mouse IgG2a did not exhibit such effects.

CONCLUSION

These results suggest the possibility that AECA can react with antigens such as TM that are present on the EC surface and activate ECs. Such events on ECs may lead to vascular inflammation and damage in patients with connective tissue diseases and vasculitis in which AECA are present.

Antiendothelial cell antibodies in vasculitis and connective tissue disease

Antiendothelial cell antibodies (AECA) are a heterogeneous family of antibodies reacting with endothelial cell antigens. These antibodies are found in various diseases and recognise several antigen determinants. Different pathophysiological effects have been observed in in vitro experiments, which include direct or indirect cytotoxicity and endothelial cell apoptosis. Furthermore, some AECA activate endothelial cells, resulting in increased leucocyte adhesiveness, activation of coagulation and vascular thrombosis. In animal models, it has been shown that AECA could promote vascular damage. Neither the endothelial cell antigens nor their precise role in the pathogenecity of different diseases in which AECA are found is well characterised. Nowadays, it is not known whether AECA are an epiphenomenon accompanying vascular injury or whether they are pathogenic. It is controversial whether fluctuations in AECA titres are associated with disease activity during follow-up studies. This review summarises the present knowledge about AECA, AECA antigens and their potential role in the pathogenecity of vasculitis and connective tissue diseases.

The Role of Endothelial Cell Reactive Antibodies in Peripheral Arterial Disease

OBJECTIVES

It is hypothesised that endothelial cell reactive antibodies (ECRA) play a role in the progression of PAD through activation of endothelial cells and the release of inflammatory cytokines. We aimed to test this hypothesis by assessing levels of ECRA, E-selectin and IL-6 in patients with PAD of varying severity in a case controlled study. DESIGN, MATERIALS, METHODS: Patients were assessed clinically and with ankle-brachial pressure indices. Patients with critical ischaemia (CI, n=30), stable claudicants (SC, n=30), and age-matched controls (AMC, n=20) were studied. Antibody, E-selectin and IL-6 levels were measured using ELISA.

RESULTS

ECRA levels were significantly raised in the CI group over AMC. IL-6 levels were significantly elevated in both SC and CI over the control group and in CI over SC. There were no significant differences in E-selectin levels between the AMC, SC and CI.

CONCLUSION

Our findings support the hypothesis that autoantibodies play a role in promoting PAD by elevating IL-6. The absence of an elevation in E-selectin in this study may be due to its short half-life, and casts doubt on its value as a marker of inflammation in atherosclerosis.

Induction of apoptosis and fibrillin 1 expression in human dermal endothelial cells by scleroderma sera containing anti–endothelial cell antibodies

OBJECTIVE

Sera from patients with scleroderma (systemic sclerosis [SSc]) contain anti-endothelial cell antibodies (AECAs) capable of inducing endothelial cell apoptosis. We sought to determine whether SSc sera containing anticentromere antibodies (ACAs) or anti-topoisomerase I antibodies (or, anti-Scl-70 antibodies) contain subsets of AECAs that trigger distinct pathways of apoptosis and gene expression in normal adult human dermal endothelial cells (HDECs).

METHODS

Adult HDECs were grown to subconfluence and treated with control or SSc patient sera. Apoptosis was investigated by differential interference contrast (DIC) microscopy, microarrays of proapoptotic gene expression, caspase 3 protease activity, and flow cytometry for phosphatidyl serine translocation.

RESULTS

Flow cytometry and DIC microscopy demonstrated that HDECs exposed to SSc sera containing either SSc autoantibody underwent apoptosis at much higher levels than those treated with control sera. While unique gene expression profiles were induced in HDECs by stimulation with SSc sera containing the respective autoantibody, similar patterns of increased gene expression of transcripts for the proapoptotic protease caspase 3 as well as the SSc autoantigen fibrillin 1 were demonstrated. Caspase 3 gene expression correlated with increased protease activity, and targeted inhibition of this protease partly blocked SSc serum-induced apoptosis. Immunohistochemistry studies of serum-stimulated HDECs demonstrated the aberrant expression of fibrillin 1 protein only in apoptotic endothelial cells treated with SSc sera containing AECAs.

CONCLUSION

There are distinct AECA subsets in the sera of patients with limited SSc (with ACAs) and diffuse SSc (with anti-Scl-70) that induce unique patterns of HDEC gene expression in the setting of apoptosis associated with increased caspase 3 activity and the reexpression of endothelial cell fibrillin 1.

Premature atherosclerosis in systemic lupus erythematosus

Significant advances have been made in defining the spectrum of clinical manifestations and the prognosis of systemic lupus erythematosus (SLE). With the use of corticosteroids and other immunosuppressive agents as well as better management of complications such as infection, there has been a dramatic improvement in the short-term prognosis of patients who have SLE from less than 50% survival at 5 years to 93% at 5 years and 85% and 10 years. However, many patients who survive early complications of organ failure and sepsis later develop premature coronary artery disease (CAD). In this evidence-based review, the magnitude of the problem of premature atherosclerosis in SLE is defined and evaluation of the strength of association of risk factors determined to date. The authors focus on the emerging role of new modalities for noninvasive assessment of vascular health in patients who have SLE and offer a strategy for screening and management of those at risk of CAD. The article concludes with a discussion on the important questions that remain to be answered and future directions for research.

The prevalence and clinical significance of autoantibodies to plasminogen activator inhibitor 1 in systemic lupus erythematosus

We have recently described the novel autoantigen plasminogen activator inhibitor (PAI-1) in systemic lupus erythematosus (SLE). The aim of this study was to determine the prevalence and clinical significance of anti-PAI-1 autoantibodies in patients with SLE. Autoantibodies to recombinant PAI-1 were measured in retrospective sera of 48 lupus patients by immunoassay in order to assess their clinical significance. This showed that 71% of sera from 48 lupus patients had significantly elevated anti-PAI-1 autoantibodies as compared with normal control subjects (P < 0.0001). There was a weak but significant (P < 0.043) correlation with anti-dsDNA autoantibodies. In longitudinal studies, autoantibodies against PAI-1 correlated with clinical parameters measured by the BILAG disease activity index including global clinical score. Our study demonstrates the high frequency of novel autoantibodies to PAI-1 in patients with lupus. The serial clinical correlations with anti-PAI-1 autoantibodies also support the hypothesis that these autoantibodies may play a pathogenic role in lupus.

Expression of cytokine, chemokine, and adhesion molecules during endothelial cell activation induced by antibodies against dengue virus nonstructural protein 1

Vascular dysfunction is a hallmark associated with disease onset in dengue hemorrhagic fever and dengue shock syndrome. In addition to direct viral damage, immune responses to dengue virus (DV) infection may also underlie the pathogenesis of disease. We have proposed a mechanism of molecular mimicry in which Abs directed against DV nonstructural protein 1 (NS1) cross-react with endothelial cells and induce damage. In this study, we demonstrated the inflammatory endothelial cell activation induced by anti-DV NS1 via the transcription factor NF-kappaB-regulated pathway. Protein phosphorylation and NF-kappaB activation were observed after anti-DV NS1 stimulation in a human microvascular endothelial cell line-1. The cytokine and chemokine production, including IL-6, IL-8, and MCP-1, but not RANTES, in endothelial cells increased after treatment with anti-DV NS1 Abs. The expression of IL-6, IL-8, and MCP-1 was blocked by the preabsorption of anti-DV NS1 with DV NS1 or by the inhibition of NF-kappaB activation. Furthermore, the increases in both ICAM-1 expression and the ability of human PBMC to adhere to endothelial cells were also observed, and these effects were inhibited by pretreatment with anti-ICAM-1 or anti-MCP-1 Abs. Therefore, in addition to endothelial cell apoptosis, as previously reported, inflammatory activation occurs in endothelial cells after stimulation by anti-DV NS1 Abs. These results suggest the involvement of anti-DV NS1 Abs in the vasculopathy of DV infection.

The blood-brain barrier in systemic lupus erythematosus

Central nervous system (CNS) involvement may occur in 20-70% of systemic lupus erythematosus (SLE) patients where neurological symptoms are overt; this is termed neuropsychiatric lupus or NPSLE. This review summarizes evidence that damage to the brain endothelium forming the blood-brain barrier (BBB) is a contributory factor in NPSLE. The normal CNS is protected by blood-tissue barriers at three sites, the brain endothelium (BBB), the choroid plexus epithelium (blood-CSF barrier) and the arachnoid epithelium. The tight junctions of the barrier layers severely restrict entry of plasma constituents including proteins, so that the CSF and brain interstitial fluid contain low levels of protein. Methods for diagnosing BBB damage include imaging (CT, MRI) using contrast agents, and analysing protein content and profiles of CSF Changes in the albumin quotient Qalbumin show evidence for barrier damage, while changes in the immunoglobulin (Ig) index can indicate intrathecal antibody production. However, BBB damage may be transient, and hence undetected or underestimated. Few mechanistic studies exist, but the two main candidate mechanisms for BBB damage are microthrombi in cerebral vessels leading to ischaemia, and immune-mediated attack and activation of the endothelium leading to local cytokine production. Both can result in barrier breakdown. Neurological syndromes could then be secondary to damage to the BBB. The implications for treatment of NPSLE are discussed.

The role of endothelial cell reactive antibodies in peripheral vascular disease

The mechanism by which a small but significant proportion of patients with peripheral vascular disease (PVD) rapidly progress to critical ischaemia is unclear. Both experimental and clinical data suggest a role for autoantibodies in the pathogenesis of atherosclerotic disease, particularly in the accelerated atherosclerosis seen in patients with systemic lupus erythematosus and the anti-phospholipid syndrome. This review examines the evidence for a role for endothelial cell reactive autoantibodies in PVD and the potential mechanisms by which these autoantibodies could contribute to the acceleration of atherosclerosis in a proportion of patients. The identification of such markers could lead to the identification of patients with PVD who are at risk of developing critical ischaemia and may warrant early and aggressive intervention.

Use of C4d as a diagnostic adjunct in lung allograft biopsies

PURPOSE

Humoral allograft rejection is a defined mechanism for cardiac and renal graft dysfunction; C4d deposition, a stable component of complement activation, inversely correlates with graft survival. With the recent recognition of humoral rejection in lung grafts, we examined C4d's role as a prognostic adjunct in lung allografts.

MATERIAL AND METHODS

Twenty-three lung recipients underwent biopsies for deterioration in clinical status or routine surveillance. Clinically unwell patients possessed acute rejection or bronchiolitis obliterans syndrome (BOS). Biopsies attributable to infection were excluded from the study. In addition to routine light microscopy, an attempt was made to correlate the clinical status and morphologic findings with the pattern of C4d deposition and also to compare these clinical and morphologic parameters with the other assessed immunoreactants. Panel reactive antibody testing was also carried out at various points in their post transplantation course whereby in 6 of the cases the samples were procured at exactly the same time as the tissue samples.

RESULTS

The patients were segregated into two groups: those patients with recurrent acute rejection and those with BOS. In those patients with symptomatic acute rejection, all biopsies showed light microscopic and immunofluorescent evidence of humoral allograft rejection. The level of C4d was positively correlated with the degree of parenchymal injury, the hallmark being one of septal capillary necrosis. In addition, high and intermediate levels of C4d correlated with a clinical diagnosis of acute rejection. C4d was the strongest predictor of parenchymal injury and of the clinical status (p <.0001) compared to other the immunoreactants C1q, C5b-9 and immunoglobulin. There was no specific correlation between C4d deposition and the presence of acute cellular rejection. In those patients fulfilling clinical criteria of BOS, deposits of C4d as well as other immunoreactants were found in the bronchial wall as opposed to the rarity of this finding in bon-BOS patients. However the only statistically significant predictor of BOS was bronchial wall deposition of C1q. In no case were panel reactive antibodies at significant levels discovered post transplantation.

CONCLUSIONS

In the context of acute rejection, C4d deposition correlates with clinical evidence of rejection and the degree of humoral rejection assessed pathologically; there is no association with the presence of histocompatibility related antibodies. It is a more specific predictor of allograft status compared to other immunoreactants. C4d deposition within the bronchial wall is a feature of BOS and hence may be used as a marker of chronic graft dysfunction. The antigenic target resulting in C4d deposition may not be histocompatibility related.

Detection of antiendothelial cell antibodies by an enzyme-linked immunosorbent assay using antigens from cell lysate: minimal interference with antinuclear antibodies and rheumatoid factors

The objective of the present work was to set up a routine test adapted to screening for antiendothelial cell antibodies (AECAs) in serum samples with minimal interference from antinuclear antibodies (ANAs) or rheumatoid factors (RFs). We compared the titers of AECAs titrated following two enzyme-linked immunosorbent assays (ELISAs): (i) an ELISA with ethanol-fixed EA.hy926 monolayers as the antigenic substrate and (ii) an ELISA with nucleus-depleted lysates prepared from EA.hy926 cells and normalized for protein (1.0 to 1.7 mg/ml) and DNA (< or =0.1 microg/ml) contents as a surrogate substrate (postnuclear supernatant ELISA [PNS-ELISA]). The AECA titers in 51 serum samples, including 28 samples containing ANAs, were compared. A significantly positive correlation (r = 0.77; P < 0.001) between the two series was shown only for the ANA-negative serum samples. Conversely, ANAs or RFs in samples were shown not to interfere in tests for AECAs by the PNS-ELISA. AECAs recognize their antigenic targets in postnuclear supernatants, which is representative of the endothelial antigenic content, with improvement of the reliability of the assay, a prerequisite to application of the assay for their evaluation in clinical practice.

The role of anti-endothelial cell antibodies in Kawasaki disease - in vitro and in vivo studies

Kawasaki disease (KD) is a systemic vasculitis with cardiac and noncardiac complications. Anti--endothelial cell antibodies (AECA) are found among many patients with KD. The aim of this study was to investigate the pathogenic role of AECA in KD using in vitro and in vivo experimental models. F(ab)2 fragments of IgG-AECA and IgM-AECA were affinity purified from a patient with active KD. Their endothelial binding and ability to induce a pro-adhesive and a pro-inflammatory phenotype were evaluated in vitro. Twenty Balb/C mice were immunized with KD-AECA or with control Ig (N-Ig) to induce AECA in a murine model by the idiotypic manipulation method. Both KD-AECA isotypes bind significantly to human umbilical vein endothelial cell (HUVEC) compared to N-Ig. The in vitro activity was demonstrated by the antibodies ability to activate endothelial cells resulting in increased IL-6 secretion, adhesion molecule expression and monocytic cell line (U937) adherence to HUVEC. Five of the mice that received KD-AECA developed murine AECA after 3 months. None of the mice that received N-Ig produced AECA. The murine AECA increased monocyte adhesion to EC in vitro, similarly to the AECA used for immunization. Furthermore, all the mice that developed AECA had proteinuria and IgG deposition in the renal mesangium. No histological or immunofluorescence evidence of cardiac vasculitis could be detected. AECA might play a role in the emergence of some of KD manifestations.

Circulating endothelial cells: tea leaves for renal disease

Fully differentiated endothelial cells and their precursors circulate in the bloodstream. Since their initial description more than 30 years ago, circulating endothelial cells have been quantified in a number of different clinical conditions that affect the endothelium. Only recently, however, have investigators begun to examine the protein expression and functionality of these cells. Because a number of diseases prevalent in the field of nephrology affect endothelial cells, the study of circulating endothelial cells may allow the direct examination of the state of the endothelium in these conditions. This review will discuss the endothelium and renal disease, the methods to quantify these circulating endothelial cells, their origins, and their therapeutic potential.