Pathogenesis of diseases associated with antineutrophil cytoplasm autoantibodies

New Insights into Pathogenesis and Treatment of ANCA-Associated Vasculitis: Autoantibodies and Beyond

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a group of rare systemic diseases affecting small-caliber vessels. The damage caused by AAV mainly involves the lung and kidneys. AAV includes three different types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Although the different phenotypic forms of AAV share common features, recent studies have shown that there are significant differences in terms of pathogenetic mechanisms involving both the adaptive and innate immune systems. Advances in our understanding of pathogenesis have enabled the development of immuno-targeted therapies. This review illustrates the characteristics of the various forms of AAV and the new therapies available for this disease that can have lethal consequences if left untreated.

Pathogenesis-based new perspectives of management of ANCA-associated vasculitis

While the pathogenesis of anti-neutrophil cytoplasmic autoantibody associated vasculitis (AAV) is still not fully elucidated, there is a mounting evidence that it is initiated by inflammation and activation of innate immunity in the presence of predisposing factors, innate immunity, aberrant responses of the adaptive immune system, and complement system activation. Biologics targeting inflammation-related molecules in the immune system have been explored to treat AVV, and these treatments have provided revolutionary advances. When focusing on the pathogenic mechanisms of AVV, this review presents the new findings regarding novel therapeutic approaches for the management of these conditions.

Killing three birds with one BPI: Bactericidal, opsonic, and anti-inflammatory functions

Bactericidal/permeability-increasing protein (BPI) is an anti-microbial protein predominantly expressed in azurophilic granules of neutrophils. BPI has been shown to mediate cytocidal and opsonic activity against Gram-negative bacteria, while also blunting inflammatory activity of lipopolysaccharide (LPS). Despite awareness of these functions in vitro, the magnitude of the contribution of BPI to innate immunity remains unclear, and the nature of the functional role of BPI in vivo has been submitted to limited investigation. Understanding this role takes on particular interest with the recognition that autoimmunity to BPI is tightly linked to a specific infectious trigger like Pseudomonas aeruginosa in chronic lung infection. This has led to the notion that anti-BPI autoantibodies compromise the activity of BPI in innate immunity against P. aeruginosa, which is primarily mediated by neutrophils. In this review, we explore the three main mechanisms in bactericidal, opsonic, and anti-inflammatory of BPI. We address the etiology and the effects of BPI autoreactivity on BPI function. We explore BPI polymorphism and its link to multiple diseases. We summarize BPI therapeutic potential in both animal models and human studies, as well as offer therapeutic approaches to designing a sustainable and promising BPI molecule.

An updated advance of autoantibodies in autoimmune diseases

Autoantibodies are abnormal antibodies which are generated by pathogenic B cells when targeting an individual's own tissue. Autoantibodies have been identified as a symbol of autoimmune disorders and are frequently considered a clinical marker of these disorders. Autoimmune diseases, including system lupus erythematosus and rheumatoid arthritis, consist of a series of disorders that share some similarities and differences. They are characterized by chronic, systemic, excessive immune activation and inflammation and involve in almost all body tissues. Autoimmune diseases occur more frequently in women than men due to hormonal impacts. In this review we systemically introduce and summarize the latest advances of various autoantibodies in multiple autoimmune diseases.

Aptamers for Proteins Associated with Rheumatic Diseases: Progress, Challenges, and Prospects of Diagnostic and Therapeutic Applications

Nucleic acid aptamers capable of affine and specific binding to their molecular targets have now established themselves as a very promising alternative to monoclonal antibodies for diagnostic and therapeutic applications. Although the main focus in aptamers’ research and development for biomedicine is made on cardiovascular, infectious, and malignant diseases, the use of aptamers as therapeutic or diagnostic tools in the context of rheumatic diseases is no less important. In this review, we consider the main features of aptamers that make them valuable molecular tools for rheumatologists, and summarize the studies on the selection and application of aptamers for protein biomarkers associated with rheumatic diseases. We discuss the progress in the development of aptamer-based diagnostic assays and targeted therapeutics for rheumatic disorders, future prospects in the field, and issues that have yet to be addressed.

Efficacy of prostaglandina E1 for the treatment of patients with thrombo-occlusive vasculitis: A protocol of systematic review and meta-analysis

BACKGROUND

This study aims to explore the efficacy and safety of prostaglandina E1 (PE1) for the treatment of patients with thrombo-occlusive vasculitis (TOV).

METHODS

Electronic databases (Cochrane Library, PUBMED, EMBASE, Web of Science, Scopus, the Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure) will be sought from onset to the March 1, 2020 without language and publication status restrictions. We will include any potential randomized controlled trials that examined the efficacy of PE1 for the treatment of patients with TOV. We will appraise study quality using Cochrane risk of bias tool, and will assess the evidence quality using Grading of Recommendations Assessment Development and Evaluation. We will use RevMan 5.3 Software for statistical analysis.

RESULTS

A high-quality synthesis of present evidence of PE1 for the treatment of patients with TOV will be provided in this study.

CONCLUSION

This study will provide evidence to judge whether PE1 is an effective intervention for TOV.

SYSTEMATIC REVIEW REGISTRATION

INPLASY202040081.

"NETtling" the host: Breaking of tolerance in chronic inflammation and chronic infection

How and why we break tolerance to self-proteins still remains a largely unanswered question. Neutrophils have been identified as a rich source of autoantigens in a wide array of autoimmune diseases that arise as a consequence of different environmental and genetic factors, e.g. rheumatoid arthritis (RA), lupus, vasculitis, cystic fibrosis (CF) etc. Specifically, neutrophil extracellular trap (NET) formation has been identified as a link between innate and adaptive immune responses in autoimmunity. Autoantigens including neutrophil granular proteins (targeted by anti-neutrophil cytoplasmic antibodies, ANCA) as well as post-translationally modified proteins, i.e. citrullinated and carbamylated proteins targeted by anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein antibodies (ACarPA), respectively, localize to the NETs. Moreover, NETs provide stimuli to dendritic cells that potentiate adaptive autoimmune responses. However, while NETs promote inflammation and appear to induce humoral autoreactivity across autoimmune diseases, the antigen specificity of autoantibodies found in these disorders is striking. These unique autoantigen signatures suggest that not all NETs are created equal and that the environment in which NETs arise shapes their disease-specific character. In this review article, we discuss the effects of different stimuli on the mechanism of NET formation as well as how they contribute to antigen specificity in the breaking of immune tolerance. Specifically, we compare and contrast the autoreactive nature of NETs in two settings of chronic airway inflammation: one triggered by smoking, a recognized environmental NET stimulus in RA patients, and one mediated by Pseudomonas aeruginosa, the most prevalent lung pathogen in CF patients. Finally, we draw attention to novel findings that, together with the specific environmental/chemical stimuli, should be taken into account when investigating how and why antigen specificity arises in the context of NET formation.

Novel insights into the aetiology of granulomatosis with polyangiitis-a case-control study using the Clinical Practice Research Datalink

Objectives

We aimed to provide insights into the aetiology of granulomatosis with polyangiitis (GPA), by conducting a large case-control study using a general population-based, prospectively collected database of healthcare records.

Methods

We compared all incident cases of GPA in the Clinical Practice Research Datalink 1990-2014, with up to 10 age-, sex- and general practice-matched controls. We identified potential risk factors, recorded numbers of cases and controls exposed to each, and calculated odds ratios (ORs) using conditional logistic regression. Our main analysis excluded data recorded during 1 year before diagnosis, to prevent early symptoms being mistaken for risk factors.

Results

We identified 757 people with GPA and matched 7546 controls. People with GPA were five times more likely to have a previous diagnosis of bronchiectasis (OR = 5.1, 95% CI: 2.7, 9.4; P < 0.0001), and these effects remained stable in diagnoses recorded >5 years prior to diagnosis. People with GPA were two to three times more likely than controls to have previous diagnoses of autoimmune diseases or chronic renal impairment, and these effects also remained stable >5 years prior to diagnosis. People with GPA were more likely to have a diagnosis of pulmonary fibrosis (OR = 5.7, 95% CI: 1.7, 19.5; P = 0.01) and sinus infections (OR = 2.7, 95% CI: 1.8, 4.2; P < 0.0001) recorded in the 3 years before diagnosis, but not before this. We also found former smoking, some medications and higher socio-economic status significantly, but less strongly, associated.

Conclusion

We found novel long-term associations between GPA and pre-existing bronchiectasis and autoimmune diseases.

Autoimmune liver disease and the enteric microbiome

The human enteric microbiome is highly complex and has more than 150 times more genes within it than its host. The host and the microbiome have a commensurate relationship that can evolve over time. The typically symbiotic relationship between the two can become pathogenic. The microbiome composition in adults reflects their history of exposure to bacteria and environmental factors during early life, their genetic background, age, interactions with the immune system, geographical location, and, most especially, their diet. Similarly, these factors are thought to contribute to the development of autoimmune disease. It is possible that alterations in the intestinal microbiome could lead to liver disease. There is emerging data for the contribution of the microbiome in development of primary sclerosing cholangitis, primary biliary cholangitis, and autoimmune hepatitis; liver disorders associated with aberrant immune function in genetically susceptible individuals.

Review article: the pathogenesis of pouchitis

BACKGROUND

A total proctocolectomy followed by ileal pouch-anal anastomosis is a potentially curative surgery for ulcerative colitis or familial adenomatous polyposis. About 5-35% of patients with ulcerative colitis and 0-11% of patients with familial adenomatous polyposis develop subsequent inflammation of the ileal pouch termed pouchitis.

AIM

To provide a comprehensive analysis of the research studying the possible pathogenesis of pouchitis. The goals were to identify promising areas of investigation, to help focus clinicians, researchers and patients on how to better understand and then potentially manage ileal pouchitis, and to provide avenues for future research investigations.

METHODS

This review examined manuscripts from 1981 to 2015 that discussed and/or proposed hypotheses with supportive evidence for the potential underlying pathogenic mechanism for pouchitis.

RESULTS

The pathogenesis of pouchitis is not definitively understood, but various hypotheses have been proposed, including (i) recurrence of ulcerative colitis, (ii) dysbiosis of the ileal pouch microbiota, (iii) deprivation of nutritional short-chain fatty acids, (iv) mucosal ischaemia and oxygen-free radical injury, (v) host genetic susceptibility and (vi) immune dysregulation. However, none of these alone are able to fully explain pouchitis pathogenesis.

CONCLUSIONS

Pouchitis, similar to inflammatory bowel disease, is a complex disorder that is not caused by any one single factor. More likely, pouchitis occurs through a combination of both dysregulated host inflammatory mechanisms and interaction with luminal microbiota.

Neutrophilic Dermatoses in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A French Multicenter Study of 17 Cases and Literature Review

A few reports suggest combination of ANCA-associated vasculitis (AAV) and neutrophilic dermatoses (ND). We aimed to describe the main characteristics of patients presenting with both AAV and ND in a French cohort and through a systematic literature review, and to discuss the possible common pathogenic process involved. We conducted a retrospective study of patients with both conditions. Patients were selected via the French Internal Medicine Society (SNFMI) and the French Vasculitis Study Group (FVSG). A literature review focusing on a combination of both conditions, concentrated only on publications with well-established diagnoses and individual detailed data. Seventeen patients diagnosed with AAV and ND were identified in this cohort. Twelve patients had granulomatosis with polyangiitis (GPA), 4 had microscopic polyangiitis (MPA) and one had eosinophilic GPA (EGPA). Eight patients, all with GPA, displayed pyoderma gangrenosum (PG). Sweet's syndrome was observed in 6 patients (4 with MPA, one with GPA and one with EGPA) and erythema elevatum diutinum in the other three (2 with GPA and 1 with MPA). The literature review identified 33 additional patients with both conditions, including 26 with GPA. Altogether, of the 50 patients (17 from our study and 33 from the literature review), 33 (66%) patients presented with PG associated with GPA in 29 cases (89%). Corticosteroids were the first-line treatment in conjunction with an immunosuppressive agent in most cases. Outcomes were good and a total of 15 patients experienced a relapse. Patients who relapsed were more likely to have ear, nose and throat manifestation than patients who did not [12/15 (80%) relapsing patients vs. 15/35 (43%) non-relapsing patients; p = 0.03)]. In our stud, the most frequent association concerned GPA and PG. ND should be considered and specifically researched within the spectrum of cutaneous manifestations observed in AAV.

Prostatitis and acute urinary retention as first manifestations of Wegnener's granulomatosis

OBJECTIVES

We present a case of prostatitis with acute urinary retention as a rare initial manifestation of Wegener' Granulomatosis.

METHODS

The case was a 48-year-old male with symptoms of prostatitis over ten days. The patient presented urinary retention, with partial response to antibiotic treatment. High levels of cytoplasmic antineutrophil cytoplasmic antibody and a prostatic biopsy were compatible with Wegener' Granulomatosis.

RESULTS

After starting treatment with glucocorticoids and cyclophosphamide, a significant improvement to the point of disappearance of symptoms was observed. At 3 months pulmonary and upper airway symptoms began, requiring higher doses of cyclophosphamide to control symptoms.

CONCLUSIONS

Wegener's Granulomatosis is a multisystem entity whose presentation as prostatitis with urinary retention is rare.

Relevance of the mouse model as a therapeutic approach for neutrophil proteinase 3-associated human diseases

Proteinase 3 (PR3) is one of the four elastase-related serine proteinases stored in the azurophilic granules of neutrophils. Although it participates in the pro- and anti-inflammatory responses to infection and inflammation it also retains specific functions that make it different from neutrophil elastase in spite of their close structural resemblance. PR3 is involved in the immune response to infection and is the major autoantigen in granulomatosis with polyangiitis (GPA, formerly Wegener disease), an autoimmune systemic vasculitis with granulomas. Thus, PR3 appears to be a relevant therapeutic target in a variety of inflammatory human diseases. Animal models are required for the testing of new drugs that target PR3 specifically but differences between human and rodent neutrophil PR3 expression and substrate specificity have greatly impaired progress in this direction. This may explain that, to date, there is no spontaneous model of vasculitis associated with anti-PR3 antibodies. In this review, we will focus on the structural and functional differences between human and murine PR3, and how these differences may be by-passed in order to develop a relevant animal model.

The role of positive feedback loops involving anti-dsDNA and anti-anti-dsDNA antibodies in autoimmune glomerulonephritis

Autoimmune glomerulonephritis (GN) is a potentially life-threatening renal inflammation occurring in a significant percentage of systemic lupus erythematosus (SLE) patients. It has been suggested that GN develops and persists due to a positive feedback loop, in which inflammation is promoted by the deposition in the kidney of immune complexes (IC) containing double-stranded DNA (dsDNA) and autoantibodies specific to it, leading to cellular death, additional release to circulation of dsDNA, continuous activation of dsDNA-specific autoreactive B cells and further formation of IC. We have recently presented a generic model exploring the dynamics of IC-mediated autoimmune inflammatory diseases, applicable also to GN. Here we extend this model by incorporating into it a specific B cell response targeting anti-dsDNA antibodies-a phenomenon whose occurrence in SLE patients is well-supported empirically. We show that this model retains the main results found for the original model studied, particularly with regard to the sensitivity of the steady state properties to changes in parameter values, while capturing some disease-specific observations found in GN patients which are unaccountable using our previous model. In particular, the extended model explains the findings that this inflammation can be ameliorated by treatment without lowering the level of anti-dsDNA antibodies. Moreover, it can account for the inverse oscillations of anti-dsDNA and anti-anti-dsDNA antibodies, previously reported in lupus patients. Finally, it can be used to suggest a possible explanation to the so-called regulatory role of TLR9, found in murine models of lupus; i.e., the fact that the knockdown of this DNA-sensing receptor leads, as expected, to a decrease in the level of anti-dsDNA antibodies, but at the same time results in a counter-intuitive amplification of the autoreactive immune response and an exacerbated inflammation. Several predictions can be derived from the analysis of the presented model, allowing its experimental verification.

Perinuclear antineutrophil cytoplasmic autoantibodies in dogs infected with various vector-borne pathogens and in dogs with immune-mediated hemolytic anemia

OBJECTIVE

To determine the prevalence of perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) in dogs with confirmed or suspected immune-mediated hemolytic anemia (IMHA) or dogs infected with various vector-borne pathogens, including Rickettsia rickettsii, Bartonella henselae, Bartonella vinsonii subsp berkhoffii, Ehrlichia canis, Borrelia burgdorferi, and Leishmania infantum.

ANIMALS

55 dogs with confirmed or suspected IMHA, 140 dogs seroreactive for vector-borne pathogens, and 62 healthy dogs and dogs seronegative for vector-borne pathogens.

PROCEDURES

Samples were allocated to subgroups on the basis of the health status of the dogs and the degree of seroreactivity against various vector-borne pathogens. Serum samples were tested retrospectively via indirect immunofluorescence assay to determine pANCA status.

RESULTS

26 of 55 (47%) dogs with confirmed or suspected IMHA and 67 of 140 (48%) dogs seroreactive for vector-borne pathogens had positive results when tested for pANCA. Serum samples with the highest antibody concentrations against L infantum antigen had the highest proportion (28/43 [65%]) that were positive for pANCA. One of 20 (5%) dogs seronegative for tick-borne pathogens and 8 of 22 (36%) dogs seronegative for L infantum had positive results for pANCA. One of 20 (5%) healthy dogs had serum antibodies against pANCA.

CONCLUSIONS AND CLINICAL RELEVANCE

pANCA were detected in a high percentage of dogs with IMHA and vector-borne infectious diseases. Therefore, pANCA may be a relatively nonspecific marker for dogs with inflammatory bowel disease, although they could represent a biomarker for immune-mediated diseases and infections.

A case of ANCA-associated vasculitis with glomerular eosinophilic infiltration: a possible pathogenic implication

We present a 58-year-old male patient with myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis with rapidly progressive glomerulonephritis. He failed to fulfill the common American College of Rheumatology criteria for eosinophilic granulomatosis with polyangiitis and was tentatively diagnosed with microscopic polyangiitis. Kidney biopsy showed pauci-immune crescentic necrotizing glomerulonephritis with neutrophilic and eosinophilic infiltration. Previous reports implicate eosinophils in the pathogenesis of this disease. Therefore, this case suggests that infiltrated eosinophils as well as neutrophils might play roles in the development of tissue injury in systemic vasculitis.

Four cases of MPO-ANCA-positive vasculitis with otitis media, and review of the literature

Otitis media is one of the common organ injuries that appear during the course of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We experienced four patients with myeloperoxidase (MPO)-ANCA-positive AAV with otitis media. All were elderly Japanese women. MPO-ANCA in our patients was reminiscent of microscopic polyangiitis (MPA), although chest computed tomography (CT) scans revealed characteristics of both granulomatosis with polyangiitis (GPA), showing bronchial lesions and nodule formation, and MPA, showing interstitial changes. Whether our cases should be classified as GPA or MPA is a matter of discussion. We detail their profiles, and review previous literature on MPO-ANCA-positive AAV with otitis media.

PTU-induced ANCA-positive vasculitis: an innocent or a life-threatening adverse effect?

Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitides are rare, but they can be triggered by chemicals, infections and drugs; among them, antithyroid drugs are common. Autoimmune disorders, such as vasculitis, are unusual, but serious complications of antithyroid therapy. Both propylthiouracil (PTU) and methimazole may induce ANCA-associated vasculitis. PTU-induced vasculitides may have different organ involvement patterns. Herein, we report four cases with ANCA-associated vasculitis with different clinical manifestations.

Neutrophil extracellular traps contain mitochondrial as well as nuclear DNA and exhibit inflammatory potential

Neutrophils expel extracellular traps (NETs) to entrap and exterminate the invaded micro-organisms. Acute/chronic inflammatory disorders are often observed with aberrantly enhanced NETs formation and high nitric oxide (NO) availability. Recent study from this laboratory demonstrated release of NETs from human neutrophils following treatment with SNP or SNAP. This study is an extension of our previous finding to explore the extracellular bacterial killing, source of DNA in the expelled NETs, their ability to induce proinflammatory cytokines release from platelets/THP-1 cells, and assessment of NO-mediated free radical formation by using a consistent NO donor, DETA-NONOate. NO-mediated NETs exhibited extracellular bacterial killing as determined by colony forming units. NO-mediated NETs formation was due to the activation of NADPH oxidase and myeloperoxidase. NO- or PMA-mediated NETs were positive for both nuclear and mitochondrial DNA as well as proteolytic enzymes. Incubation of NETs with human platelets enhanced the release of IL-1β and IL-8, while with THP-1 cells, release of IL-1β, IL-8, and TNFα was observed. This study demonstrates that NO by augmenting enzymatic free radical generation release NETs to promote extracellular bacterial killing. These NETs were made up of mitochondrial and nuclear DNA and potentiated release of proinflammatory cytokines.

Neutrophil elastase, proteinase 3, and cathepsin G as therapeutic targets in human diseases

Polymorphonuclear neutrophils are the first cells recruited to inflammatory sites and form the earliest line of defense against invading microorganisms. Neutrophil elastase, proteinase 3, and cathepsin G are three hematopoietic serine proteases stored in large quantities in neutrophil cytoplasmic azurophilic granules. They act in combination with reactive oxygen species to help degrade engulfed microorganisms inside phagolysosomes. These proteases are also externalized in an active form during neutrophil activation at inflammatory sites, thus contributing to the regulation of inflammatory and immune responses. As multifunctional proteases, they also play a regulatory role in noninfectious inflammatory diseases. Mutations in the ELA2/ELANE gene, encoding neutrophil elastase, are the cause of human congenital neutropenia. Neutrophil membrane-bound proteinase 3 serves as an autoantigen in Wegener granulomatosis, a systemic autoimmune vasculitis. All three proteases are affected by mutations of the gene (CTSC) encoding dipeptidyl peptidase I, a protease required for activation of their proform before storage in cytoplasmic granules. Mutations of CTSC cause Papillon-Lefèvre syndrome. Because of their roles in host defense and disease, elastase, proteinase 3, and cathepsin G are of interest as potential therapeutic targets. In this review, we describe the physicochemical functions of these proteases, toward a goal of better delineating their role in human diseases and identifying new therapeutic strategies based on the modulation of their bioavailability and activity. We also describe how nonhuman primate experimental models could assist with testing the efficacy of proposed therapeutic strategies.

The paradox of the neutrophil's role in tissue injury

The neutrophil is an essential component of the innate immune system, and its function is vital to human life. Its production increases in response to virtually all forms of inflammation, and subsequently, it can accumulate in blood and tissue to varying degrees. Although its participation in the inflammatory response is often salutary by nature of its normal interaction with vascular endothelium and its capability to enter tissues and respond to chemotactic gradients and to phagocytize and kill microrganisms, it can contribute to processes that impair vascular integrity and blood flow. The mechanisms that the neutrophil uses to kill microorganisms also have the potential to injure normal tissue under special circumstances. Its paradoxical role in the pathophysiology of disease is particularly, but not exclusively, notable in seven circumstances: 1) diabetic retinopathy, 2) sickle cell disease, 3) TRALI, 4) ARDS, 5) renal microvasculopathy, 6) stroke, and 7) acute coronary artery syndrome. The activated neutrophil's capability to become adhesive to endothelium, to generate highly ROS, and to secrete proteases gives it the potential to induce local vascular and tissue injury. In this review, we summarize the evidence for its role as a mediator of tissue injury in these seven conditions, making it or its products potential therapeutic targets.

Modeling immune complex-mediated autoimmune inflammation

A number of autoimmune diseases are thought to feature a particular type of self-sustaining inflammation, caused by the deposition of immune complexes (IC) in the inflamed tissue and a consequent activation of local effector cells. The persistence of this inflammation is due to a positive feedback loop, where autoantigen particles released as part of the tissue damage caused by the inflammation stimulate autoreactive B cells, leading to the formation of further immune complexes and their subsequent deposition. We present a mathematical model for the exploration of IC-mediated autoimmune inflammation and its clinical implications. We characterize the possible differences between normal individuals and those susceptible to such inflammation, and show that both random perturbations and bifurcations can lead to disease onset. Our model explains how defects in the mechanisms responsible for cellular debris clearance contribute to the development of disease, in agreement with empirical evidence. Moreover, we show that parameters governing the dynamics of immune complexes, such as their clearance rate, have an even stronger effect in determining the behavior of the system. We demonstrate the existence of hysteresis, implying that once IC-mediated autoimmune inflammation is triggered, its long-term suppression may be difficult to achieve. Our results can serve to guide the development of novel therapies to autoimmune diseases involving this type of inflammation.

Arterial Distensibility in Chronic Inflammatory Rheumatic Disorders

The pulse wave velocity (PWV), as an indicator of arterial distensibility, may play an important role in the stratification of patients based on the cardiovascular risk. PWV inversely correlates with arterial distensibility and relative arterial compliance. Decreased arterial distensibility alters arterial blood pressure and flow dynamics, and disturbes coronary perfusion. Systemic immune and inflammatory diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are associated with increased morbidity and mortality, predominantly due to adverse cardiovascular events. Systemic inflammation in these disorders may alter arterial compliance and arterial distensibility and, through this effect, lead to accelerated atherosclerosis. We have demonstrated an increase in the carotid-femoral (aortic) PWV that is a technique in which large artery elasticity is assessed from analysis of the peripheral arterial waveform, in patients with chronic inflammatory conditions such as RA, SLE, familial Mediterranean fever (FMF), Wegener’s granulomatosis (WG), sarcoidosis, psoriasis and psoriatic arthritis except Behçet’s disease (BD). In this review, the issue of arterial stiffness in RA, SLE, as well as WG, psoriasis, FMF, BD, sarcoidosis, systemic sclerosis (SS) and Takayasu's arteritis (TA) is overviewed.

Arterial distensibility in chronic inflammatory rheumatic disorders

The pulse wave velocity (PWV), as an indicator of arterial distensibility, may play an important role in the stratification of patients based on the cardiovascular risk. PWV inversely correlates with arterial distensibility and relative arterial compliance. Decreased arterial distensibility alters arterial blood pressure and flow dynamics, and disturbes coronary perfusion. Systemic immune and inflammatory diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are associated with increased morbidity and mortality, predominantly due to adverse cardiovascular events. Systemic inflammation in these disorders may alter arterial compliance and arterial distensibility and, through this effect, lead to accelerated atherosclerosis. We have demonstrated an increase in the carotid-femoral (aortic) PWV that is a technique in which large artery elasticity is assessed from analysis of the peripheral arterial waveform, in patients with chronic inflammatory conditions such as RA, SLE, familial Mediterranean fever (FMF), Wegener's granulomatosis (WG), sarcoidosis, psoriasis and psoriatic arthritis except Behçet's disease (BD). In this review, the issue of arterial stiffness in RA, SLE, as well as WG, psoriasis, FMF, BD, sarcoidosis, systemic sclerosis (SS) and Takayasu's arteritis (TA) is overviewed.

Prevalence and clinical significance of antineutrophil cytoplasmic antibody in Graves' patients treated with propylthiouracil

Development of antineutrophil cytoplasmic antibody (ANCA) during therapy with propylthiouracil (PTU) is not uncommon and PTU-induced ANCA-positive vasculitis is also reported. The aim of this study was to assess the presence and clinical significance of ANCA positivity in Graves' patients treated with PTU. Newly diagnosed Graves' disease patients (prospective group, n = 58) were evaluated before and during therapy with PTU to investigate the development of ANCA positivity. ANCA positivity is also investigated in previously diagnosed Graves' patients who had already been receiving PTU treatment (cross-sectional group, n = 51). Comparisons with Hashimoto thyroiditis (n = 55) and toxic nodular goitre (n = 20) patients, and healthy control subjects (n = 20) were carried out to define the possible influence of hyperthyroidism and/or thyroid autoimmunity on ANCA positivity. At baseline evaluation, ANCA was negative in all newly diagnosed Graves' patients. Only 28 of the 58 patients in prospective group completed 2 years of follow-up which occurred at 3-month intervals. ANCA positivity was detected 32.1% (n = 9) in a mean period of 11.7 +/- 6.1 months in prospective group. Only two (3.9%) patients in a cross-sectional group had ANCA positivity in a mean treatment period of 7.6 +/- 4.6 months. None of the patients with ANCA positivity developed symptoms and signs related to vasculitis. None of the patients with Hashimoto thyroiditis and toxic nodular goitre, and healthy control subjects had ANCA positivity. PTU therapy is associated with asymptomatic production of ANCA in a time-dependent manner, which mostly disappears after discontinuation of therapy. Hyperthyroidism or autoimmunity per se does not appear to have effect on development of ANCA positivity.

Ankle-brachial pressure index: a simple tool for assessing cardiovascular risk in patients with systemic vasculitis

OBJECTIVE

Cardiovascular disease may be increased in patients with systemic vasculitides (SV). The Ankle-Brachial Pressure Index (ABPI) is a non-invasive tool for the assessment of cardiovascular risk (CV). Our aim was to determine the prevalence of an abnormal ABPI in patients with SV and healthy controls and to correlate with clinical and serological parameters.

METHODS

We studied 54 consecutive vasculitis patients (20 males) attending the vasculitis clinic and 49 healthy subjects. Patients were classified according to the ACR 1990 criteria and the Chapel Hill Consensus definitions. There were 18 patients with Wegener's granulomatosis, eight with Behcet's disease, seven with Churg-Strauss Syndrome, three with Henoch-Schonlein purpura, three with polyarteritis nodosa, three with Takayasu's disease, three with p-ANCA associated vasculitis, three with urticarial vasculitis, two with cutaneous leucocytoclastic angiitis, one with microscopic polyangiitis, one with primary central nervous system angiitis, one giant cell arteritis and one with cutaneous vasculitis secondary to Sjogren's syndrome. Traditional risk factors as well as glucose, lipid profile, CRP, hsCRP, ANCA and aPL were assessed. ABPI was measured according to a consensus statement on the methodology.

RESULTS

The ABPI was abnormal in 11/54 (20.4%) of SV patients and 2/49 (4%) of the control group (chi(2) with Yates correction = 4.8, P <or= 0.03). CV events were more prevalent in the SV patients with abnormal ABPI (45.5% vs 11.6%, P <or= 0.01).

CONCLUSIONS

There is an increased prevalence of an abnormal ABPI in patients with systemic vasculitides implying an increased risk of cardiovascular disease. This simple tool may be clinically useful in identifying systemic vasculitis patients at risk of accelerated atherosclerosis.

Association of LILRA2 (ILT1, LIR7) splice site polymorphism with systemic lupus erythematosus and microscopic polyangiitis

Leukocyte immunoglobulin-like receptors (LILRs) are inhibitory, stimulatory or soluble receptors encoded within the leukocyte receptor complex. Some LILRs are extensively polymorphic, and exhibit evidence for balancing selection and association with disease susceptibility. LILRA2 (LIR7/ILT1) is an activating receptor highly expressed in inflammatory tissues, and is involved in granulocyte and macrophage activation. In this study, we examined the association of LILRA2 and adjacently located LILRA1 with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and microscopic polyangiitis (MPA). Polymorphism screening detected a LILRA2 SNP (rs2241524 G>A) that disrupts splice acceptor site of intron 6. Case-control association studies on 273 Japanese SLE, 296 RA, 50 MPA and 284 healthy individuals revealed increase of genotype A/A in SLE (12.1%, odds ratio (OR) 1.82, 95% confidence interval (CI) 1.02-3.24, P=0.041) and in MPA (16.0%, OR 2.52, 95% CI 1.07-5.96, P=0.049) compared with healthy individuals (7.0%). The risk allele caused an activation of a cryptic splice acceptor site that would lead to a novel LILRA2 isoform lacking three amino acids in the linker region (Delta 419-421). Flow cytometry indicated that this isoform was expressed on the surface of monocytes. These findings suggested that LILRA2 Delta 419-421 isoform encoded by the splice site SNP may play a role in SLE and MPA.

Anti–Endothelial Cell Autoantibodies Selectively Activate SAPK/JNK Signalling in Wegener’s Granulomatosis

The pathogenic role of anti-endothelial cell antibodies (AECA) in vascular injury is debated. It was previously shown that many patients with Wegener's granulomatosis (WG) have AECA that react with human kidney microvascular endothelial cells (EC). In addition, during active disease, renal endothelium strongly expresses the inflammatory molecules vascular adhesion protein-1 (VAP-1) and MHC class I-related antigen A (MICA). This study sought to determine whether AECA mediates this upregulation of VAP-1 and MICA and to define better the signaling pathways that are activated by these autoantibodies upon binding to EC in the kidney. Stimulation of human kidney microvascular EC with AECA IgG upregulated surface expression of MICA and VAP-1, elicited a rapid Ca2+ flux, induced high levels of the chemokines monocyte chemoattractant protein-1 and granulocyte chemotactic protein-2, induced specific phosphorylation of stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and the transcription factors c-Jun and activating transcription factor-2, and activated NF-kappaB. Specific inhibitors of SAPK/JNK significantly reduced AECA-induced chemokine production and phosphorylation of c-Jun and activating transcription factor-2 and abrogated protein expression of MICA but not VAP-1. In kidney sections from patients with WG, infiltrating cells that expressed the ligand for MICA (NKG2D+) were identified, as were CD8+ and 32 gamma delta+ T cells. In conclusion, AECA may be involved in the pathogenesis of WG, and the SAPK/JNK pathway and the endothelial inflammatory protein VAP-1 may be novel therapeutic targets for vasculitis.

Systemic antineutrophil cytoplasmic antibody vasculitis in a patient with chronic lymphocytic leukemia

There might be rheumatic manifestations of malignant diseases, especially those of the hematological type. Until now, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in chronic lymphocytic leukemia (CLL) has been reported on only very few occasions. Here, we present our patient with Rai stage II CLL who came to us with constitutional symptoms. She turned out to have hematuria with dysmorphic erythrocytes and developed hemoptysis. She had pulmonary-renal syndrome and was diagnosed with p-ANCA positive microscopic polyangiitis. She is currently using prednisolone and cyclophosphamide and undergoing regular hemodialysis. Constitutional symptoms in patients with hematological malignancies should make the physicians consider systemic vasculitis after exclusion of disease-related complications.

Increased membrane expression of proteinase 3 during neutrophil adhesion in the presence of anti proteinase 3 antibodies

We investigated membrane proteinase 3 (mPR3) expression during TNF-alpha-induced adhesion of neutrophils in the presence of anti-PR3 antibodies, a situation occurring during anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis. Three increasing levels of mPR3 expression were observed on the mPR3(+) neutrophil subset after stepwise cell activation. TNF-alpha activation without adhesion, TNF-alpha-induced adhesion, and adhesion in the presence of anti-PR3 mAb or human anti-PR3 ANCA resulted, respectively, in a two-, seven-, and 24-fold increase of mPR3 levels. In plasma, anti-PR3 antibodies poorly recognized suspended neutrophils, whereas they bound to mPR3 on adherent cells. mPR3 upregulation was also triggered by IL-8, formyl-methionyl-leucyl-phenylalanine (fMLP), and neutrophil adhesion to activated human umbilical vein endothelial cells. It involved beta2 integrins and Fcgamma receptor, because it was prevented by anti-CD18 antibodies and was not observed with anti-PR3 F(ab')(2). Furthermore, it was specific to anti-PR3 mAb, and no mPR3 upregulation was observed with anti-myeloperoxidase or anti-HLA-ABC mAb. Newly expressed mPR3 molecules, after TNF-induced adhesion, were mobilized from secretory vesicles (CD35(+)) and secondary granules (CD11b(+)). The adhesion- and antibody-dependent upregulations of mPR3 expression occurred with little azurophilic granule degranulation, no sign of apoptosis, and no further CD177 upregulation. In conclusion, this study describes an amplifying loop in polymorphonuclear neutrophil activation process, whereby ANCA are involved in the membrane expression of their own antigen during cell adhesion. This could explain the restriction of ANCA-associated vasculitis to small vessels, the main site of neutrophil adhesion.

The relation of initial methimazole dose to the incidence of methimazole-induced agranulocytosis in patients with Graves' disease

The relation between the incidence of methimazole (methylmercaptoimidazole; MMI)-induced agranulocytosis and initial MMI dose was evaluated in a group of 514 patients with Graves' disease who were treated between 1995 and 2005. One hundred and forty-six (28.40%) patients had received an initial dose of 30 mg MMI and 277 (53.89%) patients had been treated with 15 mg MMI. Nine patients (1.75%) developed agranulocytosis due to MMI treatment. Six (4.11%) of 146 patients who received an initial dose of 30 mg MMI, two (4.54%) of 44 patients given an initial dose of 20 mg MMI, and one (0.36%) of 277 patients given an initial dose of 15 mg MMI developed agranulocytosis. There was a statistically significant difference in agranulocytosis incidence between patients receiving an initial dose of 30 mg MMI and those who received an initial dose of 15 mg. Although 8 (4.10%) of 195 patients in the high-dose group (20 mg or higher) developed agranulocytosis, only 1 (0.31%) of 319 patients in the low-dose group (15 mg or lower) did. In conclusion, the incidence of agranulocytosis with low-dose MMI therapy was ten times lower than that of the high-dose regimen.

Chimeric antibodies to proteinase 3 of IgG1 and IgG3 subclasses induce different magnitudes of functional responses in neutrophils

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCA) are associated with small-vessel vasculitis and have been implicated in its pathogenesis. The subclass distribution of ANCA IgG deviates from normal patterns, and it has been suggested that the IgG3 subclass may have pathogenic potential over the IgG1 subclass and may be more likely to be associated with active disease and renal involvement.

OBJECTIVE

To deal with potential pathogenicity, chimeric antibodies were constructed of IgG1 and three subclasses with human IgG1 or three constant regions and a murine-derived variable region that binds an epitope within the ANCA antigen proteinase 3 (PR3) that is recognised by human autoantibodies.

METHODS

The antibodies were characterised for binding to PR3, including affinity and avidity, before being used as tools to explore their ability to activate human neutrophils for superoxide release, cytokine release, degranulation and ability to induce neutrophil adhesion under flow.

RESULTS

Both subclass antibodies elicited similar neutrophil responses for superoxide release, degranulation and interleukin (IL) 8 production, although quantitative responses showed that the IgG1 subclass favoured degranulation and the IgG3 subclass favoured IL8 production. Both antibodies were able to convert neutrophils from selectin-dependent rolling adhesion to integrin-dependent stationary adhesion in a flow assay.

CONCLUSIONS

These findings indicate that humanised antibodies directed against a single epitope of PR3 can recapitulate the effects of polyclonal human ANCA, which recognises multiple PR3 epitopes. Further, PR3-ANCA of both IgG1 and IgG3 subclasses can activate neutrophils, although the more potent IL8 response by IgG3 PR3-ANCA may encourage further neutrophil recruitment and amplify injury.

Anti-Neutrophil Cytoplasmic Autoantibodies: A Renewed Paradigm in Periodontal Disease Pathogenesis?

In the past, various models including the autoimmunity model have been proposed to explain the pathogenesis of periodontal diseases. The aim of this review is to introduce the pathogenic role of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in various autoimmune diseases and compare these conditions with periodontal disease to elucidate common pathogenic mechanisms. Also, a novel model to explain the pathogenesis of periodontal disease based on the concept of ANCA-associated autoimmunity is proposed. This encompasses a wide array of biochemical mediators that range from direct and indirect initiators of ANCA production and eventual release of proinflammatory mediators and free radicals, all of which have been implicated in periodontal tissue destruction in the past. In addition, specific links between the typical ANCA-associated diseases and periodontal disease are discussed. Finally, a new paradigm in the periodontal disease-associated destruction is proposed that includes the currently accepted mechanism, namely, the genetic-microbial-host interactions.

Childhood microscopic polyangiitis associated with MPO-ANCA

We reviewed the clinical, histological and serological parameters of microscopic polyangiitis (MPA) associated with antineutrophil cytoplasmic antibodies (ANCA) specific to myeloperoxidase (MPO). Six girls and one boy aged 12.0+/-2.6 years (7-15 years) met the following inclusion criteria: (1) clinical manifestations of systemic small vessel involvement; (2) histological demonstration of pauci-immune necrotizing glomerulonephritis; and (3) serological findings of increased concentration of MPO-ANCA by ELISA test. The main clinical manifestations were: influenza-like symptoms (100%), hematuria/proteinuria (100%), purpura (100%), pulmonary-renal syndrome (57%), acute renal failure (ARF) (29%), ischemic cerebral insults (29%), and necrotizing vasculitis of the skin (29%). All patients underwent renal biopsy examined by immunohistochemistry with expression of alpha-smooth muscle actin (alpha SMA) in glomerular and interstitial spaces. Patients were followed from 6 months to 5.5 years (35.4+/- 23.2 months). None of the patients died. Two of seven children who had ARF progressed to end stage renal disease; one developed chronic renal failure, and four normalized renal function. ARF and central nervous system involvement at presentation were parameters of poor renal outcome. A high score of fibro-cellular glomerular crescents was associated with worse prognosis. Early treatment enables a favorable prognosis of MPO-ANCA-associated MPA in children.

Antineutrophil cytoplasmic antibody (ANCA)-associated autoimmune diseases induced by antithyroid drugs: comparison with idiopathic ANCA vasculitides

Clinical and serological profiles of idiopathic and drug-induced autoimmune diseases can be very similar. We compared data from idiopathic and antithyroid drug (ATD)-induced antineutrophil cytoplasmic antibody (ANCA)-positive patients. From 1993 to 2003, 2474 patients were tested for ANCA in the Laboratory for Allergy and Clinical Immunology in Belgrade. Out of 2474 patients, 72 (2.9%) were anti-proteinase 3 (PR3)- or anti-myeloperoxidase (MPO)-positive and their clinical and serological data were analyzed. The first group consisted of ANCA-associated idiopathic systemic vasculitis (ISV) diagnosed in 56/72 patients: 29 Wegener's granulomatosis (WG), 23 microscopic polyangiitis (MPA) and four Churg-Strauss syndrome. The second group consisted of 16/72 patients who became ANCA-positive during ATD therapy (12 receiving propylthiouracil and four receiving methimazole). We determined ANCA and antinuclear (ANA) antibodies by indirect immunofluorescence; PR3-ANCA, MPO-ANCA, anticardiolipin (aCL) and antihistone antibodies (AHA) by ELISA; and cryoglobulins by precipitation. Complement components C3 and C4, alpha-1 antitrypsin (α1 AT) and C reactive protein (CR-P) were measured by nephelometry. Renal lesions were present in 3/16 (18.8%) ATD-treated patients and in 42/56 (75%) ISV patients (p <0.001). Skin lesions occurred in 10/16 (62.5%) ATD-treated patients and 14/56 (25%) ISV patients (p <0.01). ATD-treated patients more frequently had MPO-ANCA, ANA, AHA, aCL, cryoglobulins and low C4 (p <0.01). ISV patients more frequently had low α1 AT (p = 0.059) and high CR-P (p <0.001). Of 16 ATD-treated patients, four had drug-induced ANCA vasculitis (three MPA and one WG), while 12 had lupus-like disease (LLD). Of 56 ISV patients, 13 died and eight developed terminal renal failure (TRF). There was no lethality in the ATD-treated group, but 1/16 with methimazole-induced MPA developed pulmonary-renal syndrome with progression to TRF. ANCA-positive ISV had a more severe course in comparison with ATD-induced ANCA-positive diseases. Clinically and serologically ANCA-positive ATD-treated patients can be divided into two groups: the first consisting of patients with drug-induced WG or MPA which resemble ISV and the second consisting of patients with LLD. Different serological profiles could help in the differential diagnosis and adequate therapeutic approach to ANCA-positive ATD-treated patients with symptoms of systemic disease.

Distinct tumour necrosis factor alpha, interferon gamma, interleukin 10, and cytotoxic T cell antigen 4 gene polymorphisms in disease occurrence and end stage renal disease in Wegener's granulomatosis

BACKGROUND

Cytokines and T cell regulatory proteins play an important role in the pathogenesis of Wegener's granulomatosis (WG).

OBJECTIVE

To investigate cytokine and cytotoxic T cell antigen-4 (CTLA4) gene polymorphisms and HLA class II alleles in generalised WG.

METHODS

The distribution of cytokine and cytotoxic T cell antigen 4 (CTLA4) gene polymorphisms and HLA class II alleles was analysed in 32 patients with generalised WG and 91 healthy controls. Genotyping was carried out for HLA-DRB1 and HLA-DQB1 and for polymorphism of the genes encoding TNF alpha (-238, -308, -376), TGF beta (codon 10 and 25), IFN gamma (+874), IL6 (-174), IL10 (-592, -819, -1082), CTLA4 (-318, +49), and the (AT)(n) repeats of the CTLA4 gene. In addition, stratification analysis was carried out according to the presence (n = 15) or absence (n = 17) of end stage renal disease.

RESULTS

An increase in the IFN gamma +874 T/T (odds ratio (OR) = 3.14) and TNF alpha -238 G/A (OR = 5.01) genotypes was found in WG patients. When ESRD positive and negative patients were compared, the IFN gamma +874 A/A and the CTLA4 -318 C/C genotypes were found more often in the ESRD subgroup (OR = 10.6 and OR = 2.25). WG patients without ESRD had a higher frequency of the IL10 GCC/ACC promotor genotype (OR = 0.13) and long CTLA4 (AT)(n) repeats (OR = 0.4). No effect was seen for HLA-DR and -DQ markers.

CONCLUSIONS

Disease susceptibility and clinical course in WG may be associated with distinct polymorphisms of cytokine and CTLA4 genes.

Anti-endothelial cell antibodies (AECA) in patients with propylthiouracil (PTU)-induced ANCA positive vasculitis are associated with disease activity

Increasing evidence has demonstrated that propylthiouracil (PTU) could induce ANCA positive vasculitis. However, our previous work has suggested that only one-fifth of the PTU-induced ANCA positive patients had clinical vasculitis and so the mechanism is not clear. Anti-endothelial cell antibodies (AECA) have been implicated in the pathogenesis of various vasculitides, including primary ANCA positive systemic vasculitis. The purpose of this study is to investigate the prevalence of AECA and their possible role in the pathogenesis of patients with PTU-induced ANCA positive vasculitis. Sera from 11 patients with PTU-induced ANCA positive vasculitis at both active and quiescent phases, and sera from 10 patients with PTU-induced ANCA but without clinical vasculitis, were studied. Sera from 30 healthy blood donors were collected as normal controls. Soluble proteins from 1% Triton-100 extracted in vitro cultured human umbilical vein endothelial cells were used as antigens and an immunoblotting technique was performed to determine the presence of AECA, and their specific target antigens were identified. In patients with PTU-induced ANCA positive vasculitis, 10 of the 11 patients in an active phase of disease were serum IgG-AECA positive and six protein bands of endothelial antigens could be blotted (61 kD, 69 kD, 77 kD, 85 kD, 91 kD and 97 kD). However, in the quiescent phase, seven of the 10 positive sera turned negative. None of the ANCA positive but vasculitis negative patients or normal controls were AECA positive. In conclusion, AECA could be found in sera from patients with PTU-induced ANCA positive vasculitis and were associated more closely with vasculitic disease activity.