The pathogenesis of vascular changes in erythema nodosum-like lesions of Behçet's syndrome: an electron microscopic study

Mucocutaneous manifestations of Behçet's disease: Pathogenesis and management from perspectives of vasculitis

Behçet's disease (BD) is a systemic inflammatory disorder characterized by vasculitis affecting blood vessels of any caliber or type. It can present with a wide spectrum of vasculitic lesions, including erythema nodosum-like lesions and retinal vasculitis, and may also lead to larger vessel diseases, such as aortic aneurysm and deep vein thrombosis. The full etiology of BD remains unclear, but it is considered a polygenetic disease with multiple genetic risk factors that promote immune dysregulation and thrombophilia. Inflammation can be triggered by environmental factors, such as bacteria or viruses, and the dysregulation of innate and adaptive immune cell subsets. Neutrophils and lymphocytes are the primary players involved in BD pathogenesis, with specific innate (i.e., neutrophil-derived reactive oxygen species and neutrophil extracellular traps) and adaptive (i.e., anti-endothelial cell antibodies) processes inducing endothelial cell activation and chemotaxis of inflammatory cells, leading to coagulation and vasculitis. These inflammation-induced vasculitic or vasculopathic features are observed in most mucocutaneous BD lesions, although vasculitis per se is often pathologically evident only during a brief period of the disease process. Due to the multifactorial nature of BD-associated inflammation, broad-spectrum anti-inflammatory medications, including glucocorticoids and immunosuppressive drugs, have been the mainstay for managing BD. In addition, inhibitors of interleukin (IL)-1, tumor necrosis factor (TNF)-α, and IL-17, which target innate and adaptive immune functions dysregulated in BD, have emerged as promising new therapeutics. In this review, we discuss the muco-cutaneous manifestations of BD by focusing on the underlying vasculitic components in their pathologies, as well as the current array of treatment options.

[Ulcerations of the extremities: An unusual manifestation of Behçet's disease]

BACKGROUND

Although cutaneous and mucosal involvement is a major manifestation in Behçet's disease, ulcerated lesions of the extremities are exceptional and poorly known.

CASE REPORT

A 57-year-old male patient was diagnosed 7 years ago with Behçet's disease. This diagnosis was made in the presence of recurrent bipolar aphtous ulcers, pseudofolliculitis lesions and retinal vasculitis. After having been lost to follow up for two years, during which his treatment was discontinued, he presented centimetric necrotic ulcerations of the fingers of the hand and of the right big toe. The biopsy revealed leucocytoclastic and necrotizing vasculitis. The patient improved with antibiotic, oral corticosteroids, colchicine and local care.

CONCLUSION

Linking extremity ulcers with Behçet's disease, though sometimes difficult, is essential for proper management.

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.

Severe erythema nodosum due to Behçet's disease responsive to erythromycin

A patient with severe erythema nodosum due to Behçet's disease is reported on here. Erythema nodosum lesions did not respond to classical treatments; however, they cleared after erythromycin treatment, which was prescribed for the treatment of coincidental erythrasma. Erythromycin treatment appears to be an effective treatment option in erythema nodosum. The hypothetical anti-inflammatory effects of erythromycin, besides its antibiotic properties, are reviewed and discussed to explain such a clinical improvement.

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.

Clinical spectrum of Behçet's disease

Behçet's disease is a chronic systemic inflammatory disease involving mucous membranes, skin, eyes, the gastrointestinal tract, joints, blood vessels, and the neurologic system. Behçet's disease occurs endemically in the Middle East and Mediterranean regions. It is also distributed in the Central and Far Eastern Asian countries including Korea, Japan, and China. With the volume of clinical information obtained from over 5,000 patients who visited the Behçet's Disease Specialty Clinic, Severance Hospital, Yonsei University College of Medicine, informative and educational viewpoints of Behçet's disease including dermatologic and other systemic manifestations were introduced.

Histopathologic features of erythema nodosum--like lesions in Behçet disease: a comparison with erythema nodosum focusing on the role of vasculitis

Many patients with Behçet disease (BD) develop lesions that clinically resemble those of erythema nodosum (EN) but differ from that condition with regard to their microscopic features. We examined 11 sections of EN-like lesions in BD and compared them with 9 sections of classic EN using routine histopathology and immunohistochemistry so as to form a comprehensive picture of the pathologic findings in BD and to determine the role of vasculitis in the formation of lesions. Erythema nodosum-like lesions of BD are characterized by panniculitis, usually lobular or mixed septal and lobular in pattern, with variable numbers of neutrophils, lymphocytes, and histiocytes as well as variable numbers of necrotic adipocytes. Vasculitis was noted in most EN-like lesions in BD. Scattered vessels showing lymphocytic vasculitis were evident in 6 sections, and foci of leukocytoclastic vasculitis were obvious in 4 sections, sometimes with phlebitis or arteriolitis. In specimens with classic EN, we did not observe vasculitis. Only the percentages of CD3+ lymphocytes and chloroacetate esterase-positive neutrophils in the infiltrating cells showed statistically significant differences (P < 0.05) between EN-like lesions in BD and EN through immunohistochemical and enzyme cytochemical studies. Because vasculitis in the EN-like lesions in BD was extensive and not limited to areas of severe inflammation, we believe that it is primary vasculitis. We suggest that vasculitis is an important pathologic event in EN-like lesions in BD but cannot determine the extent to which other pathologic changes such as septal or lobular panniculitis, fat necrosis, neutrophilic infiltration, or microabscess formation are secondary features.

[Pathology of large vessel vasculitides]

INTRODUCTION

Vasculitides can be classified according to the size of the involved vessels. The pathological patterns of large vessel vasculitides are presented here.

CURRENT KNOWLEDGE AND KEY POINTS

They concern Buerger's disease, temporal arteritis, Takayasu's disease, Behçet's disease, infectious arteritides, rheumatologic and miscellaneous diseases. Buerger's disease is a thrombotic arteriopathy with no arterial wall involvement. Temporal arteritis and Takayasu's disease belong to the group of giant cell arteritides. In temporal arteritis, the inflammation is prominent in the internal part of the media and is aggressive for the arterial wall. In Takayasu's disease, the external part of the media is prominently involved. The fibrous thickening of the arterial wall with stenosis is characteristic. Behçet's disease can involve the large arteries with a risk of arterial rupture. Infectious arteritides are not unfrequent in vascular surgery and in previous arterial lesions. Rheumatologic diseases can result in aortitis with aortic incompetence.

FUTURE PROSPECTS AND PROJECTS

These diseases have pathological characteristics which contribute to diagnosis. However, a clearcut classification of vasculitides will come from the precise knowledge of their etiology.

Cutaneous vasculitis in Behçet's disease: a clinical and histopathologic study of 20 patients

BACKGROUND

Despite the frequency of small vessel vasculitis in skin lesions of Behçet's disease (BD), BD is classified as a neutrophilic dermatosis.

OBJECTIVE

Our goal was to determine whether the various cutaneous manifestations of BD are secondary to cutaneous vasculitis.

METHODS

Twenty-three specimens with histologically proven necrotizing vasculitis from 20 of 42 patients with BD were investigated.

RESULTS

The cutaneous vasculitic manifestations were characterized as erythema nodosum-like eruptions, palpable purpura, hemorrhagic blisters, infiltrated erythema, Sweet's syndrome-like eruptions, papulopustular lesions, and extragenital ulcerations. Combinations of various skin lesions were commonly seen in the same patient. Venous vessels in the entire dermis to the subcutis were affected with sparing of arterial vessels from middermis to subcutis. Histologic features included leukocytoclastic vasculitis in seven and lymphocytic vasculitis in 13 patients with extensive to focal localized fibrinoid necrosis of vessel walls.

CONCLUSION

Cutaneous vasculitis in BD is predominantly venulitis or phlebitis. Approximately half (48%; 20 of 42) of BD patients with cutaneous lesions had either lymphocytic (31%; 13 of 42) or leukocytoclastic vasculitis (17%; 7 of 42). We suggest that BD be considered as a vasculitis-associated disease separate from the neutrophilic dermatoses.

Plasma endothelin-1 concentrations in patients with Behçet's disease

Plasma Endothelin-1 (ET-1) concentrations were determined by radio immunoassay in 30 patients with Behçet's disease at various stages and 20 healthy subjects. Mean ET-1 plasma concentrations were significantly (p < 0.001) increased in patients with active Behçet's disease (35.99 +/- 5.06 fmol/ml, mean +/- standard error) compared to concentrations found in healthy volunteers (10.98 +/- 0.84 fmol/ml). No difference in plasma ET-1 level was observed between patients with inactive Behçet's disease (12.98 +/- 1.14 fmol/ml) and volunteers. Increased plasma levels of ET-1 in patients with Behçet's disease may be attributable to increased secretion or leakage of this mitogen from injured vascular endothelial cells. These results indicate that ET-1 may play an important pathogenetic role in the development or progression of vasculitis common to Behçet's disease. Plasma concentrations of ET-1 correlates with the activity of illness.

Ultrastructure of endothelial cell necrosis in classical erythema nodosum

As evidence of vascular involvement in classical erythema nodosum unassociated with Behçet's disease, the occurrence of endothelial cell necrosis based on the development of dark cell degeneration was observed by electron microscopy in the vasculature of the dermis and subcutaneous fat. The incidence of endothelial cell necrosis in all segments of the microcirculatory system was roughly 20% in three of 12 patients. The remaining nine patients showed a very low rate of necrosis, including two patients in whom endothelial cell necrosis was totally absent. The presence of necrotic endothelial cells that are forced out and eliminated by neighboring intact endothelial cells into the vascular lumen is closely associated with thrombus formation in the cutaneous vasculature. The incidence at which endothelial cell necrosis occurs in classical erythema nodosum is not always high; however, it is concluded that endothelial cell necrosis may play a significant role in the pathogenesis of erythema nodosum.

Erythema nodosum-like lesions in Behçet's syndrome: a histopathologic study of 30 cases

Thirty patients who fulfilled the criteria for complete and incomplete types of Behçet's syndrome were studied to determine the histopathologic changes of erythema nodosum-like lesions. Lymphocytic vasculitis was observed in 12 (40%) of the cases, but it was only focal in areas of severe lymphocytic inflammation and only mild in degree. No diffuse vasculitis was seen. It is our opinion that the observed lymphocytic vasculitis is only secondary to moderate or severe lymphocytic inflammation. Twelve cases (40%) revealed septal panniculitis, 10 cases (33%) demonstrated lobular panniculitis with moderate to marked inflammation and fat cell necrosis, and 8 cases (27%) showed mild and nonspecific inflammation in the panniculus. Therefore, there is a spectrum of histopathologic changes of erythema nodosum-like lesions in Behçet's syndrome, similar to that of erythema nodosum secondary to other systemic disorders.