Behçet's disease sera containing antiendothelial cell antibodies promote adhesion of T lymphocytes to cultured human dermal microvascular endothelial cells

Behçet's Disease as a Model of Venous Thrombosis

Behçet's disease (BD) is a chronic inflammatory disease of unknown aetiology characterized by recurrent oral, genital aphthous ulcerations, uveitis, skin lesions and other multisystem affections associated with vasculitis. Different types of vessels, predominantly veins, can be affected in BD. The frequency of vascular lesions in BD, such as superficial and deep venous thromboses, arterial aneurysms and occlusions, ranges between 7-29%. In this review, various factors of thrombogenesis in BD, particularly pro- and antithrombotic endothelial and non-endothelial factors, factors of coagulation, platelet activation and rheological changes are presented and discussed from positions of Virchow's triad of venous thrombosis. Despite advances in understanding of thrombogenesis in BD, still many issues of diagnosis and targeted preventive and therapeutic measures remain unresolved. Further studies are needed to clarify the pathobiology of BD-related thrombosis and to provide the clinicians with recommendations over the utility, safety and effectiveness of the antithrombotic therapy in BD.

Behçet’s Disease as a Model of Venous Thrombosis

Behçet’s disease (BD) is a chronic inflammatory disease of unknown aetiology characterized by recurrent oral, genital aphthous ulcerations, uveitis, skin lesions and other multisystem affections associated with vasculitis. Different types of vessels, predominantly veins, can be affected in BD. The frequency of vascular lesions in BD, such as superficial and deep venous thromboses, arterial aneurysms and occlusions, ranges between 7-29%.

In this review, various factors of thrombogenesis in BD, particularly pro- and antithrombotic endothelial and non-endothelial factors, factors of coagulation, platelet activation and rheological changes are presented and discussed from positions of Virchow’s triad of venous thrombosis.

Despite advances in understanding of thrombogenesis in BD, still many issues of diagnosis and targeted preventive and therapeutic measures remain unresolved. Further studies are needed to clarify the pathobiology of BD-related thrombosis and to provide the clinicians with recommendations over the utility, safety and effectiveness of the antithrombotic therapy in BD.

Significance of serum interleukin-8 levels in patients with Behcet's disease: high levels may indicate vascular involvement

BACKGROUND

Interleukin-8 (IL-8) has been shown previously to associate with different individual clinical manifestations and activity of Behcet's disease (BD), but its association with vascular involvement has not been established.

METHODS

Forty-five untreated patients with BD and 29 healthy individuals were included in the study. The activity of patients was based on the existence of two or more symptoms and a statistically significantly high Behcet's Disease Activity Index (BDAI) at the time of the study. IL-8, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) results were evaluated with respect to activity, vascular involvement, and other specific individual clinical manifestations of the disease.

RESULTS

IL-8 levels were found to be significantly elevated in active BD compared with inactive BD (P = 0.006) and healthy controls (P = 0.000), with median values of 267 (53-2000), 137 (52-290), and 58 pg/mL (53-160 pg/mL), respectively. Unlike ESR and CRP, IL-8 levels showed a high correlation with BDAI scores (r = 0.743, P = 0.00) and the number of active clinical manifestations (r = 0.646, P = 0.00). Serum levels of IL-8 were increased in patients with oral ulcers, genital ulcers, eye lesions, and vascular lesions, with median values and significance levels of 254.5 (53-2000), P = 0.05; 254.5 (52-1400), P = 0.03; 254.5 (72-2000), P = 0.029; and 593 pg/mL (110-2000 pg/mL), P = 0.001, respectively. In addition, IL-8 levels in the active patient group with vascular involvement were significantly higher than the levels in those without vascular involvement.

CONCLUSION

Serum IL-8 levels are increased in the active phase of BD. This marker may be useful in the early detection of vascular involvement.

No association of KIR genes with Behcet's disease

Behcet's disease (BD) is thought to be caused by multiple genetic, environmental and immunological factors, one of the most prominent being the strong association with human leucocyte antigen (HLA)-Bw51, an HLA-Bw4-associated allele. We examined the presence/absence of 14 killer cell immunoglobulin-like receptors (KIRs) and their ligands in 134 Turkish individuals with BD and compared the results with those of 154 ethnically matched controls. Although KIR3DL1 with its ligand (HLA-Bw4) was significantly increased in the patients with BD (P = 0.0003), this no longer applied when the patients and controls were categorised by HLA-Bw51 status. Thus, no association was identified between presence or absence of any of the 14 KIR genes studied and BD. In addition, we did not find any associations of KIR with various manifestations of the disease nor with gender or age of onset.

Cutaneous Vasculitis Update: Small Vessel Neutrophilic Vasculitis Syndromes

A broad and diverse spectrum of vasculitic syndromes exists. These syndromes affect the skin with varying levels of associated systemic manifestations, running the gamut from a self-limited, localized, cutaneous phenomenon to rapidly progressive, multiorgan disease. The majority of cases of cutaneous vasculitis will show a neutrophilic small vessel vasculitis that can be either a primary (idiopathic) disorder (eg, cutaneous leukocytoclastic angiitis) or a secondary disorder that is associated with drugs, infection (eg, streptococcal infection, viral hepatitis), or underlying disease (eg, connective tissue disease, malignancy). Biopsy is the gold standard for the diagnosis of cutaneous vasculitis and also necessary for the detection of cutaneous vascular immune complexes by direct immunofluorescence. Based on the type of vessel disrupted by inflammation (small and/or muscular), the distribution of vasculitis in the dermis and subcutis, and predominate inflammatory cell-type mediating vessel wall damage, a list of relevant differential diagnoses can be generated. This histologic information coupled with extravascular findings such as tissue eosinophilia, tissue neutrophilia, and/or granulomas, plus pathophysiologic markers such as direct immunofluorescent examination for immune complexes and serologic evaluation for antineutrophil cytoplasmic antibodies allows for more accurate diagnosis of specific vasculitic entities. Herein, we review both primary and secondary vasculitic syndromes that affect the skin and show a small vessel neutrophilic mediated vasculitis.

Serum interleukin-8 as a serologic marker of activity in Behçet's disease

BACKGROUND

Immune dysregulation has been shown to be one of the major aspects of the yet unknown pathogenesis of Behçet's disease. Interleukin-8 (IL-8), a major chemokine with pivotal effects concerning leukocytes and endothelial cells, has been found to be elevated in patients with Behçet's disease.

AIM

To evaluate the significance of elevated levels of IL-8 with respect to the activity of Behçet's disease.

METHODS

Sixty-seven consecutive patients with Behçet's disease (37 males, 30 females; 32.5 +/- 9.3 years) were enrolled in our study. The number of active clinical manifestations at the time of serum sampling was recorded. The degree of association between disease activity and IL-8, C-reactive protein, and erythrocyte sedimentation rate was assessed.

RESULTS

Serum levels of IL-8 increased as the number of clinically involved organs increased (P < 0.05). C-reactive protein and the erythrocyte sedimentation rate showed no correlation with disease activity.

CONCLUSIONS

Our study confirms that the IL-8 level is a more sensitive marker of disease activity than the erythrocyte sedimentation rate and C-reactive protein. It may be assumed that IL-8 plays an important role in the pathophysiology of Behçet's disease.

Pathogenesis of Adamantiades-Behçet's disease

The aetiology of Adamantiades-Behçet's disease remains unknown and its pathogenesis is not fully understood. Linked intrinsic and extrinsic factors are thought to contribute to the development of the disease, which probably occurs by environmental triggering of a genetically determined disorder. Transmission is solely vertical, indicating that the disease is not contagious. Genetic factors have been investigated and a significant link of HLA-B51, especially of HLA-B5101, has been identified. However, none of the functional correlates of the disease appear to be restricted by HLA-B51. Recently, the role of the genes encoding TNF, Tap proteins and MICA has been emphasised. Extrinsic pathogenetic candidates have been identified, including bacterial ( Streptococcus sanguis, Mycoplasma fermentas) and viral (human herpes virus) antigens and environmental pollution, which may cross-react with oral mucosal antigens and induce immunological mechanisms. A common factor linking some of the possible pathogenetic agents is extrinsically induced tissue stress or heat shock proteins, which react with host tissues and elicit significant Th1 cell responses. Neutrophils may also play a role in the pathogenesis of the disease, as they are attracted by macrophages and activated endothelial cells, which release cytokines and chemokines (especially IL-8) at the site of the lesions, and thus contribute to tissue damage and self maintenance of inflammation. Endothelial activation leading to a chronic local inflammation process together with platelet and serum factors enhance coagulation and thrombosis.

Human alpha-enolase from endothelial cells as a target antigen of anti-endothelial cell antibody in Behçet's disease

OBJECTIVE

To identify and recombine a protein of the human dermal microvascular endothelial cell (HDMEC) that specifically reacts with anti-endothelial cell antibody (AECA) in the serum of patients with Behçet's disease (BD), and to evaluate the usefulness of this protein in BD.

METHODS

The proteomics technique, with 2-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry, was used to identify and recombine HDMEC antigen. Western blotting and enzyme-linked immunosorbent assay (ELISA) of recombinant protein isolated by gene cloning were performed on serum from healthy controls, patients with BD, and patients with other rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus, and Wegener's granulomatosis).

RESULTS

Eighteen of 40 BD patients had serum IgM antibody to HDMEC antigen. The purified protein that reacted with AECA in BD patient sera was found to be alpha-enolase by 2-dimensional gel electrophoresis followed by immunoblotting and MALDI-TOF mass spectrometry. Recombinant alpha-enolase protein was isolated and refined by gene cloning. On Western blots, AECA-positive IgM from the sera of patients with active BD reacted strongly with recombinant human alpha-enolase. BD patient sera positive for anti-alpha-enolase did not react with human gamma-enolase. On dot-blotting, reactivity to human alpha-enolase was detected only in the IgM-positive group. Fifteen of the 18 AECA-positive sera that were positive for the HDMEC antigen showed reactivity to recombinant alpha-enolase IgM antibody by ELISA.

CONCLUSION

The alpha-enolase protein is the target protein of serum AECA in BD patients. This is the first report of the presence of IgM antibodies to alpha-enolase in endothelial cells from the serum of BD patients. Although further studies relating this protein to the pathogenesis of BD will be necessary, alpha-enolase and its antibody may prove useful in the development of new diagnostic and treatment modalities in BD.

Activation of extracellular signal regulated kinase 1/2 in human dermal microvascular endothelial cells stimulated by anti-endothelial cell antibodies in sera of patients with Behçet's disease

Anti-endothelial cell antibodies (AECA) have been detected in the sera of patients with Behçet's disease (BD). The isotype of AECA from BD is IgM recognizing 44 kDa antigen (IgM-AECA) of human dermal microvascular endothelial cells (HDMEC). After stimulation of HDMEC with AECA-positive sera from BD patients, the expression of intercellular cell adhesion molecule-1 (ICAM-1) on HDMEC increases significantly. Mitogen-activated protein kinase (MAPK) cascade is one of protein kinase families activated by a wide spectrum of extracellular stimuli. There are several subtypes, including extracellular signal regulated kinase (ERK)1/2, c-Jun NH(2) terminal kinase (JNK), and p38 cascades, and they regulate various cellular processes such as cell growth, differentiation, and inflammation. We examined the involvement of MAPK as a signal transduction pathway in the IgM-AECA-induced ICAM-1 expression. We used enzyme-linked immunosorbent assay (ELISA) and fluorescence-activated cell sorting (FACS) for detecting the induction of ICAM-1 on HDMEC. We also examined the production of tumor necrosis factor alpha (TNFalpha) or interleukin-1alpha (IL-1alpha) by HDMEC after stimulation with IgM-AECA, and checked the involvement of MAPK by Western blot assay. IgM-AECA cocktail from 8 patients with BD induced expression of the ICAM-1 on HDMEC. Neither TNFalpha nor IL-1alpha was detected by ELISA, FACS or reverse transcriptase-polymerase chain reaction in activated HDMEC cultures. IgM-AECA cocktail activated ERK1/2 and showed peak activities at 5 min after the stimulation. Specific MAPK/ERK kinase inhibitor PD98059 inhibited IgM-AECA-induced ERK1/2 activities and ICAM-1 expression on HDMEC at a concentration of 60 microM. IgM-AECA can play a pathogenic role in induction of vasculitis and inflammatory lesions of BD by directly activating endothelial cells, not by production of TNFalpha or IL-1alpha from HDMEC. ERK1/2 are involved in expression of ICAM-1 on HDMEC stimulated with IgM-AECA.

Increased expression of endothelial cell adhesion molecules due to mediator release from human foreskin mast cells stimulated by autoantibodies in chronic urticaria sera

Histamine-releasing antibodies that act against the epitope of the alpha chain of Fc(epsilon)RI (anti-Fc(epsilon)RI(alpha) antibody) that may affect pathogenesis in serum of patients with chronic urticaria. We assessed the capability of anti-Fc(epsilon)RI(alpha) antibody in sera from patients with chronic urticaria to release histamine and cytokines, and to induce the expression of endothelial cell adhesion molecules. We also assessed the release of inflammatory mediators from cultured foreskin mast cells, and expression of endothelial cell adhesion molecules on human dermal microvascular endothelial cells. Cells were pretreated with mast cell-conditioned media: culture media of mast cells treated with sera from chronic urticaria patients containing anti-Fc(epsilon)RI(alpha) antibody. Histamine release from human foreskin mast cells challenged with sera, increased after both 20 min and 16 h intervals. Leukotriene D4 release also increased at both 20 min and 16 h. Tumor necrosis factor-alpha increased significantly in foreskin mast cell culture challenged with sera of chronic urticaria patients. After the stimulation of human dermal microvascular endothelial cells with the conditioned media, the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin increased significantly. Treatment of the conditioned media with anti-tumor necrosis factor-alpha monoclonal antibody partially inhibited the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. The data suggest that sera from patients with chronic urticaria containing anti-Fc(epsilon)RI(alpha) antibody release mediators and tumor necrosis factor-alpha by activating human foreskin mast cells. This release can play a pathogenic role in chronic urticaria by activating endothelial cells, in part due to the actions of tumor necrosis factor-alpha from mast cells.

Identification of a novel autoantigen UACA in patients with panuveitis

To identify the target autoantigens in Vogt-Koyanagi-Harada disease, we made use of an immunoscreening of a bovine uveal cDNA expression library with serum samples obtained from patients with Vogt-Koyanagi-Harada disease. We identified a novel bovine antigen and homologous human autoantigen and designated it as UACA (uveal autoantigen with coiled coil domains and ankyrin repeats). mRNA of human UACA is expressed most abundantly in skeletal muscles and in various human tissues, including choroid, retina, and epidermal melanocytes. IgG autoantibodies were quantitated in an ELISA, using recombinant C-terminal 18.0% fragment of human UACA. The prevalence of IgG anti-UACA autoantibodies in patients with panuveitis (Vogt-Koyanagi-Harada disease, Behçet's disease, sarcoidosis) was significantly higher than that in healthy controls (19.6-28.1% vs 0%, P < 0.05) indicating that autoimmunity directed against UACA is a common phenomenon in these diseases.

Autoantibodies Associated with Rheumatic Diseases

The identification of circulating autoantibodies contributes to the correct diagnosis as well as to the follow-up of rheumatic diseases. Some autoantibodies are even included in diagnostic and classification criteria for these types of autoimmune diseases. There are several relatively specific screening and identification methods for the measurement of autoantibodies available. The type of assay crucially influences the diagnostic value of the parameters. In general, routine laboratories should prefer enzyme immunoassays (ELISA) using well characterized antigens, although ELISA tests tend to produce more false-positive and true weakly positive results, which reduce their positive predictive value. Therefore one should be aware that laboratory results can only be properly interpreted when there is a correlation with the clinical situation and when the limitations of the technologies used for autoantibody identification have been taken into consideration. A diagnostic algorithm consisting of screening and identification steps should be established by each laboratory in order to create a rational, evidence-based and cost-effective basis for the diagnosis of rheumatic diseases.