ABSTRACT
During laboratory monitoring of patients with rheumatic diseases it is not uncommon to notice elevated liver transaminase levels. From a rheumatological perspective there are multiple causes for this. Liver dysfunction can be the result of certain rheumatological diseases, such as systemic lupus erythematosus. Primary biliary cirrhosis and primary sclerosing cholangitis are associated with rheumatic diseases. On the other hand, hepatological diseases, such as hepatitis C and autoimmune hepatitis show rheumatological symptoms. The most common cause of elevation of liver transaminase levels in rheumatic patients is without doubt the anti-rheumatic therapy.
Subject(s)
Liver/enzymology , Rheumatic Diseases/diagnosis , Rheumatic Diseases/enzymology , Transaminases/metabolism , Biomarkers/metabolism , Diagnosis, Differential , HumansABSTRACT
The correlation between rheumatic diseases and liver diseases is complex and often not given sufficient attention. There are, however, consequences for diagnosis and therapy. Rheumatic diseases can present with hepatic symptoms while liver diseases can exhibit rheumatic symptoms. Examples of liver diseases as a cause of rheumatic symptoms are viral hepatitis B and C, autoimmune hepatitis and hemochromatosis. As a result of rheumatic diseases, such as adult onset Still's disease and systemic lupus erythematosus, liver dysfunction can occur. Autoimmune hepatitis, primary biliary cirrhosis and primary sclerosing cholangitis are directly associated with rheumatic diseases and have to be distinguished by way of differential diagnosis. During antirheumatic therapy, serious hepatotoxic side effects have to be expected.
Subject(s)
Evidence-Based Medicine , Liver Diseases/epidemiology , Liver Diseases/therapy , Rheumatic Diseases/epidemiology , Rheumatic Diseases/therapy , Comorbidity , Humans , Prevalence , Risk FactorsABSTRACT
Paraneoplastic syndromes, as syndromes associated with malignancy, can present unrelated to tumor invasion or metastases. They can occur with varying clinical appearance and are often indistinguishable from idiopathic rheumatic symptoms. Some musculoskeletal disorders are more associated with malignancies. The therapy of rheumatic syndromes can itself have an effect on the tumorigenic process. The clinical severity of paraneoplastic rheumatic symptoms can in many cases aid in the assessment of tumor activity and the response to therapy. While generally an extensive search for occult malignancies in every older rheumatoid patient in cases with no indications of malignancy is not advisable, knowledge of rheumatic symptoms associated with malignancies aids in the important early detection of tumors, while avoiding unnecessary examinations.
Subject(s)
Gastrointestinal Neoplasms/diagnosis , Paraneoplastic Syndromes/diagnosis , Rheumatic Diseases/diagnosis , Autoimmune Diseases/diagnosis , Diagnosis, Differential , Early Diagnosis , Humans , Neoplasms, Unknown Primary/diagnosis , Paraneoplastic Syndromes/etiology , Prognosis , Rheumatic Diseases/etiologyABSTRACT
The humanized anti-IL-6 receptor monoclonal antibody tocilizumab (TCZ) represents a new therapy approach for moderately severe to severe cases of rheumatoid arthritis (RA). The IL-6 concentration in the synovial fluid and peripheral circulation of patients with RA is elevated. TCZ recognises the IL-6 binding site of human IL-6R and blocks the IL-6 signaling pathway. TCZ is capable of correcting a multitude of pathological processes in RA, as has been shown in a number of studies. TCZ treatment should be combined with methotrexate. If the latter cannot be administered, TCZ can also be used as a monotherapy. The recommended dose is 8 mg/kg once every 4 weeks; the minimum dose per infusion is 480 mg. Close monitoring, in particular for infectious complications, is necessary. Clinical effects of TCZ are usually seen several weeks following initiation of therapy. If no significant clinical response is seen within 6 months, TCZ therapy should be ceased.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Arthritis, Rheumatoid/drug therapy , Delivery of Health Care/standards , Guideline Adherence/standards , Guidelines as Topic/standards , Quality Assurance, Health Care/standards , Rheumatology/standards , Antibodies, Monoclonal, Humanized , Antirheumatic Agents/administration & dosage , Arthritis, Rheumatoid/prevention & control , Germany , HumansABSTRACT
A 31-year old male patient had suffered from systemic lupus erythematosus (SLE) for 21 years. During the last 8 years he exhibited no clinical symptoms and did not receive any medical SLE treatment. He was admitted with a two-day history of dyspnea and fever. Laboratory studies revealed microcytic anemia and elevated levels of inflammation markers. Chest X-ray showed pulmonary infiltrates. The respiratory status rapidly deteriorated and the patient died 16 hours after admission. An autopsy was performed and diffuse alveolar hemorrhage in all parts of the lungs were seen, which was confirmed by microscopic examination. In contrast, lung histology did not show evidence of infection or inflammatory lesions. Additionally, membranous glomerulonephritis could be identified by light and electron microscopy. Diffuse alveolar hemorrhage (DAH) and concomittant lupus nephritis as manifestations of the known SLE were diagnosed. Acute pulmonary hemorrhage was determined as the cause of death. DAH is a rare, but serious manifestation of SLE. The diagnosis is difficult since the occurrence is abrupt and both symptoms and histology of the lesion are non-uniform and unspecific. The present case demonstrates that DAH also develops in patients that have not had clinical symptoms for several years. Since the early diagnosis is essential for the outcome, DAH should be considered in every case of SLE patients with severe pulmonary symptoms. Corticosteroids are the recommended form of therapy for this disorder.
Subject(s)
Hemorrhage/pathology , Lung Diseases/pathology , Lupus Erythematosus, Systemic/pathology , Pulmonary Alveoli/pathology , Adult , Humans , Kidney Glomerulus/pathology , Lupus Nephritis/pathology , Male , Microscopy, ElectronABSTRACT
BACKGROUND/AIM: The cholangiopathies represent hepatobiliary diseases in which bile-duct epithelial cells are targets for destructive processes, including immune-mediated damage. We describe a novel rat model of chronic fibrosing cholangitis induced by administration of the hapten reagent 2,4,6-trinitrobenzenesulfonic acid (TNBS) into the dilated bile duct. METHODS: The common bile duct was dilated due to a mild stenosis in 8-week-old female Lewis rats. TNBS (50 mg/kg) was injected during a second laparotomy. RESULTS: TNBS-treatment reproducibly resulted in chronic fibrosing cholangitis. In retrograde cholangiography the bile ducts showed irregularities, beading and strictures. Alkaline phosphatase levels remained abnormal throughout the study period. Immunohistochemical staining showed an increased number of macrophages, CD3+ T-lympbocytes and MHC class II antigen upregulation. The spontaneous interferon-gamma, tumor necrosis factor-alpha and interleukin-10 production of liver-derived mononuclear cells was increased. Anti-neutrophil cytoplasmic antibodies with specificity against myeloperoxidase, catalase and actin were found between 1 and 12 weeks after TNBS injection. CONCLUSIONS: We established a novel rat model of chronic fibrosing cholangitis with histologic, cholangiographic, serologic and immunologic similarities to human primary sclerosing cholangitis. This model may be used to study pathomechanisms of chronic cholangitis without concomitant inflammatory bowel disease.
Subject(s)
Autoantibodies/analysis , Cholangitis, Sclerosing/chemically induced , Cholangitis, Sclerosing/pathology , Trinitrobenzenesulfonic Acid , Tumor Necrosis Factor-alpha/metabolism , Animals , Antibodies, Antineutrophil Cytoplasmic/analysis , Antibodies, Antineutrophil Cytoplasmic/immunology , Bile Ducts/pathology , Cholangiography , Cholangitis, Sclerosing/diagnosis , Cholangitis, Sclerosing/immunology , Cholangitis, Sclerosing/metabolism , Chronic Disease , Epitopes , Female , Injections , Interferon-gamma/metabolism , Interleukin-10/metabolism , Liver/metabolism , Male , Rats , Rats, Inbred BUF , Rats, Inbred Lew , Trinitrobenzenesulfonic Acid/administration & dosageABSTRACT
BACKGROUND: The antiphospholipid-antibody syndrome (APS) is a thrombophilic disorder, in which venous and arterial thrombosis can occur. We report the rare case of a patient with mesenteric infarction due to primary APS. CASE REPORT: A 46-year-old male patient was admitted to the hospital because of severe abdominal pain. A laparotomy was performed and revealed infarction of a jejunal loop which was resected. At pathohistological examination mesenteric artery infarction was found. Preoperatively prolonged partial thromboplastin time led to coagulation analysis. Lupus anticoagulant and anticardiolipin antibodies were found. TREATMENT: The diagnosis of primary APS was made and the patient was treated with aspirin (100 mg/day) and low molecular weight heparin (2,500 IE/day) permanently. Eighteen months after mesenteric infarction the patient is free of further thromboembolic events.
Subject(s)
Antibodies, Anticardiolipin/blood , Antiphospholipid Syndrome/complications , Jejunal Diseases/etiology , Mesenteric Vascular Occlusion/etiology , Antiphospholipid Syndrome/blood , Antiphospholipid Syndrome/immunology , Humans , Jejunal Diseases/immunology , Jejunal Diseases/pathology , Laparotomy , Male , Mesenteric Arteries , Mesenteric Vascular Occlusion/immunology , Mesenteric Vascular Occlusion/pathology , Middle AgedSubject(s)
Autoantibodies/cerebrospinal fluid , Granulomatosis with Polyangiitis/complications , Lateral Medullary Syndrome/complications , Lateral Medullary Syndrome/diagnosis , Serine Endopeptidases/immunology , Antibodies, Antineutrophil Cytoplasmic/cerebrospinal fluid , Autoantigens/immunology , Granulomatosis with Polyangiitis/cerebrospinal fluid , Granulomatosis with Polyangiitis/immunology , Humans , Lateral Medullary Syndrome/cerebrospinal fluid , Lung/pathology , Magnetic Resonance Imaging , Male , Middle Aged , Myeloblastin , Tomography, X-Ray ComputedABSTRACT
BACKGROUND: Wegener's granulomatosis (WG) is characterized by systemic vasculitis with crescentic glomerulonephritis (CGN) and circulating autoantibodies directed against neutrophil cytoplasmic antigens (ANCA). Proteinase 3 (PR-3), a neutral serine proteinase in neutrophils implicated in the growth control of myeloid cells, has been identified as the target antigen for ANCA in WG. Since the kidneys are frequently involved in WG, we studied the in situ expression of PR-3 by renal parenchymal cells. METHODS: We assessed the expression of PR-3 in kidney biopsies of 15 patients with WG by immunohistochemistry (IHC) and in situ hybridization (ISH). Normal kidney tissue served as the control. RESULTS: We detected PR-3 mRNA and PR-3 protein in distal tubular epithelial cells (TECs) and glomerular epithelial cells (GECs) in normal kidney tissue and in CGN. Furthermore, a strong glomerular PR-3mRNA expression restricted to the site of cellular crescents was detected in patients with WG. The analysis of 144 glomeruli with cellular or sclerotic crescents revealed a positive correlation of glomerular PR-3mRNA expression with the percentage of cellular crescents per glomerulus. The capability of human TECs and GECs to synthesize PR-3 was confirmed by Northern blot and ISH on cultured cells. CONCLUSION: These data provide evidence that nonhematopoetic renal parenchymal cells express PR-3 and that glomerular expression of PR-3 is associated with crescent formation in WG. Our findings suggest that renal parenchymal cells may directly be involved in the pathogenesis of CGN in WG.
Subject(s)
Granulomatosis with Polyangiitis/metabolism , Granulomatosis with Polyangiitis/pathology , Kidney Glomerulus/metabolism , Kidney Glomerulus/pathology , RNA, Messenger/metabolism , Serine Endopeptidases/genetics , Adult , Aged , Biopsy , Cells, Cultured , Epithelial Cells/metabolism , Female , Humans , Kidney/metabolism , Kidney/pathology , Kidney Tubules/metabolism , Kidney Tubules/pathology , Male , Middle Aged , MyeloblastinABSTRACT
OBJECTIVE: Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology frequently requiring long-term therapy for control of symptoms and prevention of relapse. Azathioprine (AZA) has been shown to be effective and safe in the treatment of chronic active UC. However, the alternatives to treatment with AZA are limited. Our aim was to compare the efficacy and safety of treatment with mycophenolate mofetil (MMF)/prednisolone versus standard immunosuppressive treatment with azathioprine (AZA)/prednisolone in patients with chronic active UC. METHODS: The study was designed as an open comparison of MMF versus AZA. Twenty-four patients with active UC (Rachmilewitz score > or =6 points) were randomly assigned to the MMF (20 mg/kg)/prednisolone or AZA (2 mg/kg)/prednisolone group. The initial prednisolone dosage was 50 mg and was tapered according to a standard protocol. Treatment was scheduled for 1 yr. RESULTS: The rates of remission were higher in the AZA/prednisolone group (n = 12) than in the MMF/prednisolone group (n = 12) throughout the study. Remission rates were 92% versus 67% after 4 wk, 92% versus 67% after 3 months, 92% versus 67% after 6 months, 83% versus 78% after 9 months, and 100% versus 88% after 1 yr. The number of patients not requiring steroids was higher in the AZA/prednisolone group than in the MMF/prednisolone group. Moreover, in the AZA/prednisolone group no severe adverse events were recorded, whereas in the MMF/prednisolone group two severe adverse events were observed: one patient discontinued MMF after 6 months because of recurrent upper airway infections, and one patient exhibited a bacterial meningitis after 9 months. CONCLUSIONS: Treatment with AZA/prednisolone appears to be more effective and safe compared to MMF/prednisolone in patients with chronic active UC. MMF might be an alternative treatment for patients with contraindications to AZA. To further evaluate the effects of MMF in active UC, a placebo-controlled double-blinded study appears warranted.
Subject(s)
Azathioprine/therapeutic use , Colitis, Ulcerative/drug therapy , Immunosuppressive Agents/therapeutic use , Mycophenolic Acid/analogs & derivatives , Adult , Aged , Azathioprine/adverse effects , Chronic Disease , Drug Therapy, Combination , Female , Glucocorticoids/adverse effects , Glucocorticoids/therapeutic use , Humans , Immunosuppressive Agents/adverse effects , Male , Middle Aged , Mycophenolic Acid/adverse effects , Mycophenolic Acid/therapeutic use , Pilot Projects , Prednisolone/adverse effects , Prednisolone/therapeutic use , Remission InductionABSTRACT
BACKGROUND: In sera from patients with autoimmune liver diseases, e. g. primary sclerosing cholangitis (PSC) and autoimmune hepatitis, anti-neutrophil cytoplasmic antibodies (ANCAs) can be found. Until now, no animal model of ANCA induction in liver disease has been described. In this study, we describe a novel rat model of acute liver injury and subsequent ANCA production. MATERIALS AND METHODS: The hapten reagent 2,4,6-trinitrobenzenesulphonic acid (TNBS) was injected into the portal vein of female Lewis rats. Two experimental groups were studied: group A (TNBS/ethanol) received different TNBS concentrations; control animals of group B (ethanol) were injected with 10% (v/v) ethanol/0.9% (w/v) NaCl. RESULTS: A dose-dependent acute necrotizing liver injury occurred after injection of TNBS. Histopathological examination revealed acute hepatic injury with confluent parenchymal necrosis, mild bile duct proliferation and periportal infiltration. The periportal infiltration consisted mainly of macrophages and T lymphocytes. ANCAs were found in an allogenic test system between 1 and 8 weeks after TNBS injection in 11 out of 28 (39%) TNBS-treated rats (group A) and did not correlate with the extent of liver injury or TNBS dose. Autoantibody specificities of IgG type were directed against catalase (29%), myeloperoxidase (14%) and actin (7%), as detected by enzyme-linked immunosorbent assay and Western blotting. Moreover, autoantibodies against the asialoglycoprotein receptor were observed. Peripheral blood mononuclear cells and spleen lymphocytes from TNBS-treated rats were shown to produce ANCAs. CONCLUSION: In summary, we were able to show that intraportal administration of the hapten reagent TNBS induces an acute necrotizing liver injury with subsequent ANCA production in Lewis rats. ANCA specificities were mainly directed against catalase, an autoantigen that has recently been identified in sera from patients with primary sclerosing cholangitis and autoimmune hepatitis. This animal model offers the opportunity to study the pathomechanisms of ANCA production in necrotizing liver injury.
Subject(s)
Antibodies, Antineutrophil Cytoplasmic/analysis , Liver/drug effects , Trinitrobenzenesulfonic Acid/toxicity , Animals , Female , Fluorescent Antibody Technique, Indirect , Humans , Liver/immunology , Liver/pathology , Macrophages/immunology , Macrophages/pathology , Necrosis , Rats , Rats, Inbred Lew , T-Lymphocytes/immunology , T-Lymphocytes/pathologyABSTRACT
BACKGROUND: It has been shown that interaction of anti-PR-3 antibodies with human endothelial cells (EC) leads to an activation of EC in vitro, i.e. induction of adhesion molecules like E-selectin, VCAM-1 and tissue factor. The aim of this study was to investigate the effect of anti-PR-3 antibodies on endothelial IL-8 expression. MATERIALS AND METHODS: EC were cultured in 96-well plates and stimulated with TNF-alpha and IL-1beta for 1 h to induce membrane expression of endothelial PR-3. Anti-PR-3 antibodies were purified from sera from patients with clinically active Wegener's granulomatosis. Purified anti-Ro, anti-centromere, anti-dsDNA antibodies and a monoclonal anti-PR-3 antibody (WGM2) served as controls. Induction of IL-8 mRNA was detected by RT-PCR. IL-8 was measured in the supernatant of EC by ELISA. In addition, induction of NFkappaB was investigated by PAGE of nuclear extracts of EC and Western blot with ab against p65. RESULTS: In contrast to controls, interaction of anti-PR-3 antibodies (patients and WGM2) with cytokine activated EC led to the highest amount of IL-8 synthesis. Priming of EC with cytokines alone induced a markedly lower IL-8 level. The lowest levels of IL-8 could be measured after incubation of unprimed EC with anti-PR-3 antibodies. Anti-PR-3 antibody induced endothelial IL-8 expression could be inhibited by cycloheximide. In addition, we established that the activation of NF-kappaB is critically involved in anti-PR-3 antibody induced endothelial IL-8 production. CONCLUSION: In summary, we were able to show that anti-PR-3 antibodies induce endothelial IL-8 synthesis by activating NF-kappaB. As IL-8 represents a powerful neutrophil chemoattractant, our data provide further evidence for a direct pathogenic effect of anti-PR-3 antibodies in ANCA related diseases.
Subject(s)
Autoantibodies/immunology , Autoantigens/immunology , Endothelium, Vascular/immunology , Granulomatosis with Polyangiitis/immunology , Interleukin-8/genetics , Serine Endopeptidases/immunology , Transcription, Genetic , Antibodies, Antineutrophil Cytoplasmic/blood , Autoantibodies/pharmacology , Cells, Cultured , Endothelium, Vascular/enzymology , Granulomatosis with Polyangiitis/blood , Humans , Immunoglobulin G/immunology , Immunoglobulin G/pharmacology , Interleukin-1/pharmacology , Interleukin-8/metabolism , Myeloblastin , NF-kappa B/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Serine Endopeptidases/genetics , Tumor Necrosis Factor-alpha/pharmacology , Umbilical VeinsABSTRACT
The initial stage of Wegener's Granulomatosis (WG) is often marked by symptoms of infection and it has been postulated that a bacterial infection could be the aetiologic factor of this disease. The objective of our work was to investigate T-cell-mediated immunity in WG by testing proliferative responses on bacterial antigens and particularly Staphylococcus aureus. We investigated the bulk proliferative response of peripheral blood lymphocytes (PBL) from patients with clinically active WG to gram-positive bacteria and purified proteinase 3 (PR-3), the major target antigen of c-ANCA. We generated S. aureus-specific PBL-derived T-cell lines and T-cell clones (TLC). In two WG patients 27 TLC were characterized in terms of reactivity to bacterial antigens/PR-3, phenotype, HLA class II restriction and pattern of cytokine secretion. Compared to coagulase-negative Staphylococci and beta-haemolytic Streptococci A, reactivity to S. aureus was significantly increased in all patients with WG. Using purified PR-3, we found a PBL proliferation in five out of 25 WG patients. The TLC were S. aureus-specific and did not cross-recognize Streptococci or coagulase-negative Staphylococci. The S. aureus-specific TLC were of the alphabeta-TCR+ CD4+ phenotype and HLA-DR-restricted. These TLC predominantly showed a Th2-type of cytokine secretion. Interestingly, seven of the S. aureus-reactive TLC also recognized the PR-3 antigen. From these data we conclude that Staphylococci-specific HLA-DR-restricted CD4+ T cells may play a key role in the initial triggering of immune responses in WG.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , Cytokines/immunology , Granulomatosis with Polyangiitis/immunology , Granulomatosis with Polyangiitis/microbiology , Staphylococcal Infections/immunology , Staphylococcus aureus/immunology , Antigens, Bacterial/immunology , Cytokines/biosynthesis , Cytotoxicity, Immunologic , HumansABSTRACT
During a period of more than eleven years serum samples of a patient with Systemic Lupus Erythematosus were collected and analyzed for anti-nuclear autoantibodies. High titer of anti-La/SS-B were detectable in all serum samples. The La/SS-B epitopes remained constant. Besides anti-La/SS-B antibodies all serum samples contained traces of anti-Ro/SS-A including anti-Ro52 and anti-Ro60 antibodies. During disease flares anti-Ro/SS A antibodies were upregulated and anti-dsDNA antibodies appeared, thus supporting the concept of an antigen driven intermolecular epitope spreading to Ro/SS-A and dsDNA.
Subject(s)
Antibodies, Antinuclear/immunology , Epitope Mapping , Epitopes/immunology , Lupus Erythematosus, Systemic/immunology , Adult , Antibodies, Antinuclear/analysis , Female , HumansABSTRACT
Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown aetiology. Recent studies have shown that genetic factors and both cellular and humoral immunological abnormalities are important in the pathogenesis of PSC. The most prominent autoantibodies in PSC are anti-neutrophil cytoplasmic antibodies (ANCA). The autoepitopes of ANCA in PSC are not well defined. The aim of this study was to identify corresponding ANCA autoantigens in patients with PSC. A biochemical approach with enrichment and partial purification of soluble neutrophil proteins, detection of autoantibodies by Western blot and partial amino acid sequencing were used. Two new autoantigen/autoantibody systems in patients with PSC were detected: catalase and alpha-enolase. The presence of catalase autoantibodies in 9/15 (60%) and alpha-enolase autoantibodies in 4/15 (27%) was confirmed by ELISA and Western blot. Furthermore, we showed immunoreactions of PSC sera with human biliary epithelial cells, showed the reduction of fluorescence in anti-catalase absorption experiments and observed partial co-localization of anti-catalase antibodies and PSC sera in double-staining experiments on biliary epithelial cells. The anti-catalase antibody-positive PSC patients had a more severe course of disease with a significantly higher alkaline phosphatase compared with the anti-catalase-negative PSC patients (P < 0.06). All ulcerative colitis control sera were anti-catalase antibody-negative. The identified antigens catalase and alpha-enolase can partly explain the ANCA fluorescence on ethanol-fixed and formaldehyde-fixed granulocytes in patients with PSC. Catalase is an important anti-oxidant enzyme and prevents cell damage from highly reactive oxygen-derived free radicals. Catalase autoantibodies might play a pathogenic role in patients with PSC. Our findings support the hypothesis that oxidative stress is one of the pathogenic mechanisms in patients with PSC.
Subject(s)
Autoantibodies/immunology , Catalase/immunology , Cholangitis, Sclerosing/immunology , Phosphopyruvate Hydratase/immunology , Amino Acid Sequence , Autoantibodies/blood , Autoimmunity , Blotting, Western , Cholangitis, Sclerosing/blood , Enzyme-Linked Immunosorbent Assay , Humans , Molecular Sequence DataABSTRACT
Anti-neutrophil cytoplasmic antibodies (ANCAs) targeting proteinase 3 (PR3) have a high specifity for Wegener's granulomatosis (WG), and their role in activating leukocytes is well appreciated. In this study, we investigated the influence of PR3-ANCA and murine monoclonal antibodies on human umbilical vascular endothelial cells (HUVECs). Priming of HUVECs with tumor necrosis factor alpha induced endothelial upregulation of PR3 message and surface expression of this antigen, as measured by Cyto-ELISA, with a maximum occurrence after 2 h. Primed cells responded to low concentrations of both antibodies (25 ng-2.5 microg/ml), but not to control immunoglobulins, with pronounced, dose-dependent phosphoinositide hydrolysis, as assessed by accumulation of inositol phosphates. The signaling response peaked after 20 min, in parallel with the appearance of marked prostacyclin and platelet-activating factor synthesis. The F(ab)2 fragment of ANCA was equally potent as ANCA itself. Disrupture of the endothelial F-actin content by botulinum C2 toxin to avoid antigen-antibody internalization did not affect the response. In addition to the metabolic events, anti-PR3 challenge, in the absence of plasma components, provoked delayed, dose-dependent increase in transendothelial protein leakage. We conclude that anti-PR3 antibodies are potent inductors of the preformed phosphoinositide hydrolysis-related signal tranduction pathway in human endothelial cells. Associated metabolic events and the loss of endothelial barrier properties suggest that anti-PR3-induced activation of endothelial cells may contribute to the pathogenetic sequelae of autoimmune vasculitis characterizing WG.
Subject(s)
Antibodies, Antineutrophil Cytoplasmic/immunology , Antibodies, Monoclonal/immunology , Endothelium, Vascular/immunology , Granulomatosis with Polyangiitis/immunology , Serine Endopeptidases/immunology , Signal Transduction , Cell Communication , Cells, Cultured , E-Selectin/metabolism , Endothelium, Vascular/drug effects , Endothelium, Vascular/pathology , Enzyme-Linked Immunosorbent Assay , Granulomatosis with Polyangiitis/pathology , Humans , Myeloblastin , Phosphatidylinositols/metabolism , Platelet Activating Factor/metabolism , Polymerase Chain Reaction , Tumor Necrosis Factor-alpha/pharmacology , Vascular Cell Adhesion Molecule-1/metabolismABSTRACT
At present, the exact mechanism of the pathogenic effect of anti-PR-3 antibodies remains unknown. Interaction of anti-neutrophil cytoplasmic antibodies (ANCAs) with human umbilical vein endothelial cells (HUVECs) may play a key role. Recently we were able to show that ANCAs recognize their target antigen, PR-3, translocated into the membrane of HUVECs. The objective of this study was to investigate regulation, i.e. signal transduction pathways, of PR-3 expression in endothelial cells. HUVECs were isolated according to the method of Jaffe et al. and cultured under standard conditions. A cyto-enzyme-linked immunosorbent assay (ELISA) with unfixed cells was performed. Membrane-expressed PR-3 was detected by affinity-purified and monoclonal anti-PR-3 Ab. Tumour necrosis factor alpha (TNF-alpha)-induced membrane expression of PR-3 could be blocked with the RNA synthesis inhibitor actinomycin D, the protein kinase C (PKC) and proteinase A (PKA) inhibitor staurosporine, the specific PKA inhibitor calphostin C, the c-AMP-dependent PKA inhibitor KT5720 and the tyrosine kinase inhibitor genistein in a dose-dependent manner. The effect of calphostin C was the most significant. In addition, the effect of phorbol 12-myristate 13-acetate (PMA), a mediator of intracellular second messengers, was investigated. In our study, pretreatment of cells with PMA for 48 h led to a down-regulation of PR-3 expression. This effect, however, could be overridden by TNF-alpha stimulation, i.e. TNF-alpha-induced membrane expression of PR-3 was resistant to down-regulation of PKC. In conclusion, our data suggest that translocation of PR-3 in HUVECs is an active process depending on protein synthesis. PR-3 expression by HUVECs may involve a PKC reactive to cytokines such as TNF-alpha which induces PR-3 expression at a transcriptional level.