Low Concentrations of C5a Complement Receptor Antibodies Are Linked to Disease Activity and Relapse in Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis.

OBJECTIVE: To examine concentrations of circulating antibodies targeting C3a and C5a complement receptors in antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) and analyze their association with disease activity. METHODS: Concentrations of antibodies against C3a and C5a complement receptors (anti-C3aR and anti-C5aR) and plasma complement fragments C3a and C5a were determined in patients with AAV (n = 110; granulomatosis with polyangiitis [GPA; n = 82] or microscopic polyangiitis [MPA; n = 28]), systemic lupus erythematosus (SLE) patients as disease controls (n = 36), and healthy donors (n = 220). C3aR and C5aR expression by circulating neutrophils, monocytes, and T cells was analyzed using flow cytometry. Clinical data were assessed at time of serum sampling and during follow-up for 60 months. RESULTS: In AAV, anti-C3aR and anti-C5aR antibodies were decreased (P = 0.0026 and P ≤ 0.0001, respectively). In remission, anti-C3aR antibody concentrations rose to values comparable to healthy donors, whereas anti-C5aR antibody concentrations did not. In GPA, anti-C5a and anti-C5aR antibody concentrations inversely correlated with each other (r = -0.6831, P = 0.0127). In newly diagnosed GPA, decreased concentrations of anti-C5aR antibodies but not anti-C3aR antibodies were associated with disease activity (P = 0.0009). Moreover, low anti-C5aR antibodies were associated with relapse in GPA (hazard ratio 3.54, P = 0.0009) and MPA (hazard ratio 4.41, P = 0.0041). The frequency of C5aR-expressing cells within T cell populations was increased in GPA (P = 0.0021 for CD4+ T cells; P = 0.0118 for CD8+ T cells), but not in MPA. CONCLUSION: Low concentrations of anti-C5aR antibodies reflect disease activity and are associated with an increased risk for relapse in AAV.

Increased protease-activated receptor 1 autoantibodies are associated with severe COVID-19.

In patients with severe #COVID19, increased levels of autoantibodies against PAR1 were found. These might serve as allosteric agonists of PAR1 on endothelial cells and platelets, and thus might contribute to the pathogenesis of microthrombosis in COVID-19. https://bit.ly/3pqM9Vv.

The treatment of Merkel cell carcinoma with immune checkpoint inhibitors: implications for patients with rheumatoid arthritis.

OBJECTIVES: Merkel cell carcinoma (MCC) is a rare, highly aggressive neuroendocrine skin cancer, which typically affects elderly and immunocompromised and/or immunosuppressed patients. The checkpoint inhibitor avelumab, a mAb targeting the anti-programmed cell death ligand 1 (anti-PD-L1), has revolutionized the treatment of metastatic MCC, achieving dramatic improvements in disease control and overall survival. However, checkpoint inhibitors are associated with the development of immune-related adverse events, such as exacerbation of pre-existing RA. Although most immune-related adverse events can be managed successfully with CSs, their frequent and/or long-term use runs the risk of undermining the efficacy of immune checkpoint inhibition. METHODS: We report two cases of MCC, in which immunosuppressive therapy for the management of RA was administered. RESULTS: Immunosuppression for (i) pre-existing and (ii) immune checkpoint inhibitor-exacerbated RA was associated with progression of metastatic MCC. CONCLUSION: Any decision to initiate immunosuppressive treatment for RA in patients receiving immune checkpoint inhibitor therapy should include careful consideration of the risk of potentially fatal cancer progression and be taken after consultation with the patient's oncologist and rheumatologist. When the immunosuppressive treatment is required, it should be administered for as short a time as possible and under strict clinical and radiological surveillance.

[Systemic sclerosis]. / Systemische Sklerose.

Systemic sclerosis (SSc) is a rare fibrosing rheumatic multi-systemic disease involving many medical specialties. The mortality of SSc is determined by lung fibrosis, pulmonary arterial hypertension and cardiac involvement. With early and intensive treatment, the disease can be stabilized and symptoms relieved. This review summarizes insights into pathophysiology, disease classification, clinical manifestations and successful therapies, as well as recent studies on new immunosuppressant, biological and vasoactive therapies.

GPCR-specific autoantibody signatures are associated with physiological and pathological immune homeostasis.

Autoantibodies have been associated with autoimmune diseases. However, studies have identified autoantibodies in healthy donors (HD) who do not develop autoimmune disorders. Here we provide evidence of a network of immunoglobulin G (IgG) autoantibodies targeting G protein-coupled receptors (GPCR) in HD compared to patients with systemic sclerosis, Alzheimer's disease, and ovarian cancer. Sex, age and pathological conditions affect autoantibody correlation and hierarchical clustering signatures, yet many of the correlations are shared across all groups, indicating alterations to homeostasis. Furthermore, we identify relationships between autoantibodies targeting structurally and functionally related molecules, such as vascular, neuronal or chemokine receptors. Finally, autoantibodies targeting the endothelin receptor type A (EDNRA) exhibit chemotactic activity, as demonstrated by neutrophil migration toward HD-IgG in an EDNRA-dependent manner and in the direction of IgG from EDNRA-immunized mice. Our data characterizing the in vivo signatures of anti-GPCR autoantibodies thus suggest that they are a physiological part of the immune system.

Pathogenetic and Clinical Aspects of Anti-Neutrophil Cytoplasmic Autoantibody-Associated Vasculitides.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) targeting proteinase 3 (PR3) and myeloperoxidase expressed by innate immune cells (neutrophils and monocytes) are salient diagnostic and pathogenic features of small vessel vasculitis, comprising granulomatosis with polyangiitis (GPA), microscopic polyangiitis, and eosinophilic GPA. Genetic studies suggest that ANCA-associated vasculitides (AAV) constitute separate diseases, which share common immunological and pathological features, but are otherwise heterogeneous. The successful therapeutic use of anti-CD20 antibodies emphasizes the prominent role of ANCA and possibly other autoantibodies in the pathogenesis of AAV. However, to elucidate causal effects in AAV, a better understanding of the complex interplay leading to the emergence of B lymphocytes that produce pathogenic ANCA remains a challenge. Different scenarios seem possible; e.g., the break of tolerance induced by a shift from non-pathogenic toward pathogenic autoantigen epitopes in inflamed tissue. This review gives a brief overview on current knowledge about genetic and epigenetic factors, barrier dysfunction and chronic non-resolving inflammation, necro-inflammatory auto-amplification of cellular death and inflammation, altered autoantigen presentation, alternative complement pathway activation, alterations within peripheral and inflamed tissue-residing T- and B-cell populations, ectopic lymphoid tissue neoformation, the characterization of PR3-specific T-cells, properties of ANCA, links between autoimmune disease and infection-triggered pathology, and animal models in AAV.

[Systemic sclerosis]. / Systemische Sklerose.

Systemic sclerosis is a challenging and heterogeneous disease due to the involvement of multiple organs and the high impact on morbidity and quality of life. Lung fibrosis, pulmonary arterial hypertension, and cardiac manifestations are main causes of systemic sclerosis-related deaths. In addition, patients suffer from a various range of co-morbidities such as malnutrition, depression, osteoporosis, malignancies, which are increased in these patients and have to be identified and treated. Early assessment of organ damage is a key to therapeutic success. The discovery of pathogenic autoantibodies combined with increased evidence of effective immunosuppressive and vasoactive treatment strategies are major developments in the therapy of the disease. At present, several clinical studies are ongoing and some of the biological therapies are promising.

Clinical presentation and long-term outcome of 144 patients with microscopic polyangiitis in a monocentric German cohort.

OBJECTIVE: To evaluate the clinical presentation and long-term outcome of a vasculitis centre cohort of patients with microscopic polyangiitis (MPA) with respect to organ manifestations, treatment, chronic damage and mortality. METHODS: We performed a retrospective chart review at our vasculitis referral centre. MPA patients admitted between 1991 and 2013 classified by a modified European Medicines Agency algorithm were diagnosed and treated according to a standardized interdisciplinary approach. RESULTS: Comprehensive data from standardized interdisciplinary workups was available for 144 patients (median follow-up 72 months). The overall standardized mortality ratio was 1.40 (95% CI 0.91, 2.07; P = 0.13). We observed a higher mortality [hazard ratio (HR) 4.04 (95% CI 1.21, 13.45), P = 0.02] in 17 patients with MPA-associated fibrosing interstitial lung disease (ILD) and 56 patients with peripheral nervous system involvement [HR 5.26 (95% CI 1.10, 25.14), P = 0.04] at disease onset. One hundred and fifteen patients (79.9%) responded to the initial treatment. Sixty-one (42.3%) achieved complete remission and 54 (37.5%) achieved partial remission. Twenty (13.9%) showed a refractory disease course. CONCLUSION: MPA patients at our tertiary rheumatology referral centre seemed to have a less severe phenotype resulting in a less severe disease course and better outcome than reported in other cohorts. Fibrosing ILD was significantly associated with mortality in this cohort.

Plasma cells within granulomatous inflammation display signs pointing to autoreactivity and destruction in granulomatosis with polyangiitis.

INTRODUCTION: Plasma cells residing in inflamed tissues produce antibodies in chronic inflammatory and systemic autoimmune diseases. This study examined if plasma cells, located within inflamed nasal tissue in granulomatosis with polyangiitis (GPA), express features potentially associated with the autoimmune and destructive character of this disease. METHODS: Ig gene mutation patterns of individual tissue-derived plasma cells from GPA (n = 5) were analyzed, by using laser-assisted microdissection followed by semi-nested polymerase chain reaction (PCR). Signs of B-lymphocyte maturation (ectopic lymphoid structures, ELS) and survival (a proliferation-inducing ligand, APRIL; B-cell maturation antigen, BCMA; transmembrane-activator and calcium modulator and cyclophilin interactor, TACI; receptor activator of nuclear factor κB ligand, RANKL) were examined in nasal tissues or serum, respectively, by using immunohistochemistry/fluorescence and enzyme-linked immunosorbent assay, ELISA. RESULTS: Plasma-cell derived Ig genes (light- and heavy-chain pairs, n = 4; heavy chains, n = 33) resembled mutation patterns seen in other autoimmune diseases, predominantly displaying selection against replacement mutations within the framework region of Ig genes (10 of 15), which is responsible for structural integrity. Ectopic lymphoid structures were similar between GPA and a disease control (that is, unspecific chronic rhinosinusitis. However, histomorphologic features distinguishing GPA from rhinosinusitis (that is, neutrophilic microabscess and granuloma) expressed considerable amounts of membrane-associated and secreted APRIL, respectively. The latter was co-localized with CD138 and found in close proximity to cells expressing IgG, TACI, and BCMA. Interestingly, plasma cells strongly expressed receptor activator of nuclear factor κB ligand (RANKL), apart from fibroblast-like cells. CONCLUSIONS: Plasma cells within granulomatous inflammation appear to display features that might be required for autoreactivity and, possibly, RANKL-mediated destruction in GPA.

Prospective long-term follow-up of patients with localised Wegener's granulomatosis: does it occur as persistent disease stage?

OBJECTIVE: To identify patients with localised Wegener's granulomatosis (locWG) to assess whether it occurs as a long-term disease stage or phenotype and to characterise its outcome. METHODS: Patients in a 'localised stage' with histological criteria compatible with WG and a follow-up period of ≥1 year were included. They were prospectively followed at the Vasculitis Center Schleswig-Holstein from 1989 to 2009 and the clinical manifestations, antineutrophil cytoplasmic autoantibodies (ANCA) status and damage were evaluated. Immunosuppression was adapted to disease activity and severity in a step-up regimen. RESULTS: Of 1024 patients with suspected WG, 99 were clinically diagnosed with locWG and 50 fulfilled the inclusion criteria (72% women, median age 43 years, 46% ANCA-positive). The median follow-up was 48 months. All achieved a response to treatment, 34% achieved complete remission, 1-4 relapses occurred in 46%, 5 (10%) had generalised disease (median 6 years after onset). ANCA status was not associated with relapse (p=0.98), transition to generalised disease (p=0.51) or refractory manifestations (p=0.60). 47% required cyclophosphamide for localised manifestations, 36% of them for pulmonary masses and 24% for orbital masses. 66% developed organ damage, mostly due to bony destruction or space obturation (28% saddle nose, 24% septal perforation, 10% orbital wall destruction). There were two deaths that were not related to WG. CONCLUSION: There is evidence that locWG is a long-term disease stage or phenotype (5% of all patients with WG), 46% of whom are ANCA-positive. LocWG is characterised by destructive and/or space-consuming lesions associated with high relapse rates (46%) and local damage.

Refractory central nervous system vasculitis and gastrocnemius myalgia syndrome in Crohn's disease successfully treated with anti-tumor necrosis factor-alpha antibody.

BACKGROUND: Secondary vasculitis represents a rare extraintestinal manifestation of Crohn's disease (CD). Appropriate and prompt diagnosis is often delayed by uncertainties about the relationship of the vasculitic manifestations and CD. OBJECTIVE: To describe our experience with vasculitis in CD and review the literature with respect to different manifestations and pathophysiological aspects of extraintestinal vasculitic manifestations of CD. METHODS: We report 2 new cases of CD with secondary small-vessel vasculitis. We also extensively review the literature (1960-2007) using a broad range of key words related to secondary vasculitis in CD. Relevant publications were evaluated for the number of reported patients and manifestations of vasculitis. RESULTS: Vasculitis is a rare extraintestinal manifestation of CD. Different types of vasculitis affect large-, medium-, and small-sized vessels associated with CD. Common immunologic features include intestinal inflammation as well as an infiltration of gammadelta-T-cells and/or Th1-type cells into vessel walls. The 2 new cases of secondary vasculitis in CD reported here reflect 2 major types of CD-related inflammatory vascular disorders. The first involves the central nervous system, while the second represents circumscribed Musculus gastrocnemius involvement (so-called "gastrocnemius myalgia syndrome"). Successful treatment of refractory secondary vasculitis in CD with an anti-tumor necrosis factor-alpha antibody is shown for the first time. CONCLUSION: Vasculitis secondary to CD is an uncommon finding. Therefore, it has to be carefully differentiated from other forms of primary or secondary vasculitis with intestinal involvement. Treatment with an anti- tumor necrosis factor-alpha antibody may prove a treatment option in vasculitis as an extraintestinal manifestation of CD.

BPI-ANCA of pediatric cystic fibrosis patients can impair BPI-mediated killing of E. coli DH5alpha in vitro.

Gram-negative bacterial lung infections and chronic bacterial colonization are major threats for pediatric cystic fibrosis (CF) patients. Besides impeded mucociliary clearance, other mechanisms that contribute to increased susceptibility to infections are presumed. The bactericidal/permeability-increasing protein (BPI), which is delivered by neutrophil granulocytes and mucosal epithelial cells, is one of the most potent innate antibiotics against Gram-negative bacteria and endotoxin. Antineutrophil cytoplasmic autoantibodies against BPI (BPI-ANCA) have been found in up to 90% of CF patients, and titers correlated inversely with lung function parameters. As major pulmonary damage is mediated by Gram-negative bacteria and their products, the question was raised as to whether BPI-ANCA can inhibit the antibiotic function of BPI in these patients. Sera of 23 pediatric CF patients were analyzed for the presence of BPI-ANCA by indirect immunofluorescence, ELISA, epitope mapping, and Western blotting. Patients' IgG were tested in a bacterial growth inhibition assay with recombinant BPI (rBPI) and an amino-terminal fragment of BPI (rBPI(21)) that retains antibiotic activity for inhibition of the antibiotic function of BPI against E. coli DH5alpha in vitro. BPI was recognized by 21 of 23 patients' sera in our detection assays. Thirteen of 23 patients' BPI-ANCA (56%) could inhibit the antibiotic function in vitro. Moreover, epitope mapping over the whole BPI sequence revealed that more patients' BPI-ANCA recognize the amino-terminal part of BPI than can be detected by ELISA. Thus, in pediatric CF patients, BPI-ANCA may contribute to diminished bacterial clearance by inhibiting the antibiotic function of BPI.

Autoantibodies against the bactericidal/permeability-increasing protein from inflammatory bowel disease patients can impair the antibiotic activity of bactericidal/permeability-increasing protein.

Bactericidal/permeability-increasing protein (BPI) is an antineutrophil cytoplasmic autoantibody (ANCA) target antigen in inflammatory bowel disease (IBD). The aim of this study was to characterize binding regions of BPI-autoantibodies and to analyze their ability to block the antibiotic effect of BPI. Sera of 24 ulcerative colitis and Crohn's disease patients were examined in indirect immuno-fluorescence, ANCA enzyme-linked immunosorbent assay (ELISA), and by epitope mapping with 13mer peptides and Western blot for presence of BPI-autoantibodies. IgG preparations were used to determine inhibition of BPI's antimicrobial function by BPI-autoantibodies in a bacterial growth inhibition assay. BPI-autoantibodies were detected by ELISA in 18/24 patients. Epitope mapping and western blotting revealed an additional 3 patients with BPI-autoantibodies. IgG preparations of all patients with Crohn's disease and 9 of 12 ulcerative colitis patients could inhibit the antibiotic function of BPI in vitro as compared with healthy control subjects. Inhibiting BPI-autoantibodies correlated with extraintestinal manifestations, peripheral blood leukocyte counts, and anemia. BPI-autoantibodies recognizing the N-terminal portion were associated with greater mucosal damage and intestinal extent of disease. BPI is a frequent target antigen of autoantibodies in ulcerative colitis and Crohn's disease. Inhibition of the antibiotic function mediated by the N-terminal region of BPI by these autoantibodies may contribute to a proinflammatory environment in IBD patients.