Not Everything Is as It Seems: A Case Series and Overview of Diseases Mimicking Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare heterogeneous disease in which treatment must be initiated early to prevent irreversible organ damage and death. There are several diseases that can mimic AAV, even in the presence of positive ANCA serology and/or histological evidence of vasculitis, as demonstrated in this case series. We reflect on the diagnostic approach of patients with AAV and provide an overview of AAV-mimicking diseases that can be considered in patients with atypical disease presentation or course.

Primary SARS-CoV-2 infection in patients with immune-mediated inflammatory diseases: long-term humoral immune responses and effects on disease activity.

BACKGROUND: Patients with immune-mediated inflammatory diseases (IMIDs) on immunosuppressants (ISPs) may have impaired long-term humoral immune responses and increased disease activity after SARS-CoV-2 infection. We aimed to investigate long-term humoral immune responses against SARS-CoV-2 and increased disease activity after a primary SARS-CoV-2 infection in unvaccinated IMID patients on ISPs. METHODS: IMID patients on active treatment with ISPs and controls (i.e. IMID patients not on ISP and healthy controls) with a confirmed SARS-CoV-2 infection before first vaccination were included from an ongoing prospective cohort study (T2B! study). Clinical data on infections and increased disease activity were registered using electronic surveys and health records. A serum sample was collected before first vaccination to measure SARS-CoV-2 anti-receptor-binding domain (RBD) antibodies. RESULTS: In total, 193 IMID patients on ISP and 113 controls were included. Serum samples from 185 participants were available, with a median time of 173 days between infection and sample collection. The rate of seropositive IMID patients on ISPs was 78% compared to 100% in controls (p < 0.001). Seropositivity rates were lowest in patients on anti-CD20 (40.0%) and anti-tumor necrosis factor (TNF) agents (60.5%), as compared to other ISPs (p < 0.001 and p < 0.001, respectively). Increased disease activity after infection was reported by 68 of 260 patients (26.2%; 95% CI 21.2-31.8%), leading to ISP intensification in 6 out of these 68 patients (8.8%). CONCLUSION: IMID patients using ISPs showed reduced long-term humoral immune responses after primary SARS-CoV-2 infection, which was mainly attributed to treatment with anti-CD20 and anti-TNF agents. Increased disease activity after SARS-CoV-2 infection was reported commonly, but was mostly mild. TRIAL REGISTRATION: NL74974.018.20, Trial ID: NL8900. Registered on 9 September 2020.

Traditional and disease-related cardiovascular risk factors in ANCA-associated vasculitis: A prospective, two-centre cohort study.

OBJECTIVES: ANCA-associated vasculitis (AAV) has been associated with increased risk of cardiovascular (CV) events. The aim was to assess traditional and disease-related CV risk determinants in a two-centre prospective cohort of AAV patients. METHODS: Patients were recruited from centres in the Netherlands and Canada. A comprehensive CV risk assessment was performed at inclusion. Subjects were followed up yearly for 3-5 years until the first CV event, death or end of follow-up. Cox proportional hazards analyses were performed to relate baseline characteristics to the first CV event. RESULTS: A total of 144 patients were included (mean age 62 years, female sex 44%, median Framingham risk score 14.3%). Insulin resistance was present in 73% of patients tested at inclusion, independent of concurrent prednisone therapy. After a median follow-up of 2.90 years, 16 patients (11%) experienced a CV event (14 non-fatal and 2 fatal). The incidence of CV events was 5.45 per 100 patient-years. Age, Framingham risk score, HbA1c level, Diabetes Mellitus (DM), and previous CV event were significantly associated with CV events. Other factors, such as sex, impaired renal function, dyslipidemia, hypertension, smoking history and microalbuminuria, or disease-specific variables, like ANCA serotype or disease activity, were not significantly related to CV events in univariable or age-adjusted cox regression analysis. CONCLUSIONS: Determinants of an increased CV risk were identified. Disease-related factors and treatments can further modify individual risk factors, such as for steroids causing chronic insulin resistance and DM. Treatment of risk factors is essential to optimize long-term outcomes in AAV patients.

Monocytes and macrophages in ANCA-associated vasculitis.

Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitides (AAV) are characterized by inflammation of small-to-medium-sized blood vessels and the presence of autoantibodies against cytoplasmic proteases sited in neutrophils and monocytes. Increasing evidence indicates a substantial role of monocytes and macrophages in the pathogenesis of AAV. Activated monocytes and macrophages contribute to necroinflammation in peripheral vasculitic lesions as well as to central and peripheral mechanisms of autoimmunity. The intermediate monocyte subset (CD14++CD16+) is increased and monocytes show elevated expression of CD14, Toll-like receptor 2/4, MHCII and integrins, likely reflecting activation and increased monocyte extravasation. Monocytes differentiate locally predominantly into alternatively activated (M2) macrophages, which are known for cell-clearance and phagocytosis, but may ultimately lead to fibrosis. Phagocytotic function of macrophages can be impaired by surface expression of cytoplasmic proteases on apoptotic neutrophils and causes release of inflammatory cytokines and immunogenic contents, presumably resulting in a vicious circle of increased neutrophil, T and B cell activation and consequent ANCA production. Considering their crucial role in initiating necroinflammation as well as fibrogenesis, monocytes and macrophages may represent a logic first-line target for new treatment options in AAV.