Summary: The term “vasculitis” refers to a group of rare immune‐mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small‐, medium‐, or large‐vessel vasculitides, patients show a high circulating neutrophil‐to‐lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to “set the tone” for immune cells and other cells in the vessel wall. Considering both their long‐established and newly described roles, we extend their functions far beyond their direct host‐damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti‐neutrophil cytoplasmic antibody‐associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Background The majority of patients with B-cell-depleting therapies show compromised vaccination-induced immune responses. Herein, we report on the trajectories of anti-SARS-CoV-2 immune responses in patients of the RituxiVac study compared with healthy volunteers and investigate the immunogenicity of a third vaccination in previously humoral non-responding patients. Methods We investigated the humoral and cell-mediated immune response after SARS-CoV-2 messanger RNA vaccination in patients with a history with anti-CD20 therapies. Coprimary outcomes were antispike and SARS-CoV-2-stimulated interferon-γ concentrations in vaccine responders 4.3 months (median; IQR: 3.6–4.8 months) after first evaluation, and humoral and cell-mediated immunity (CMI) after a third vaccine dose in previous humoral non-responders. Immunity decay rates were compared using analysis of covariance in linear regression. Results 5.6 months (IQR: 5.1–6.7) after the second vaccination, we detected antispike IgG in 88% (29/33) and CMI in 44% (14/32) of patients with a humoral response after two-dose vaccination compared with 92% (24/26) healthy volunteers with antispike IgG and 69% (11/16) with CMI 6.8 months after the second vaccination (IQR: 6.0–7.1). Decay rates of antibody concentrations were comparable between patients and controls (p=0.70). In two-dose non-responders, a third SARS-CoV-2 vaccine elicited humoral responses in 19% (6/32) and CMI in 32% (10/31) participants. Conclusion This study reveals comparable immunity decay rates between patients with anti-CD20 treatments and healthy volunteers, but inefficient humoral or CMI after a third SARS-CoV-2 vaccine in most two-dose humoral non-responders calling for individually tailored vaccination strategies in this population. Trial registration number NCT04877496; ClinicalTrials.gov number.

Ferroptosis is a form of iron-dependent regulated cell death caused by the accumulation of lipid peroxides. In this review, we summarize research on the impact of ferroptosis on disease models and isolated cells in various types of arthritis. While most studies have focused on rheumatoid arthritis (RA) and osteoarthritis (OA), there is limited research on spondylarthritis and crystal arthropathies. The effects of inducing or inhibiting ferroptosis on the disease strongly depend on the studied cell type. In the search for new therapeutic targets, inhibiting ferroptosis in chondrocytes might have promising effects for any type of arthritis. On the other hand, ferroptosis induction may also lead to a desired decrease of synovial fibroblasts in RA. Thus, ferroptosis research must consider the cell-type-specific effects on arthritis. Further investigation is needed to clarify these complexities.

Objectives: To investigate the proportion and distribution of contrast enhancement (CE) of musculoskeletal structures with MRI of the thorax/abdomen/pelvis in giant cell arteritis (GCA). Methods: CE at 34 musculoskeletal sites was rated with a four-point ordinal scale. Patients were divided into groups with or without glucocorticoid (GC) treatment and with or without symptoms of polymyalgia rheumatica (PMR). Two composite scores were created: an MRI score, including seven sites, and a limited MRI score, including four sites. Results: Retrospectively, 90 consecutive patients with GCA were included. The population included 54 and 36 patients with and without PMR symptoms, respectively, and 45 (50%) patients were receiving GCs at the time of MRI. CE was found in 90.7% of lumbar spines, 87.5% of the pelvis, 82.2% of shoulder girdles and in 95.6% at any site in patients without GCs. The proportion of patients without and with GCs with at least moderate enhancement was, respectively, 91.1% and 75.6% at ≥1–3 sites, 75.6% and 51.1% at ≥4–6 sites, and 64.4% and 28.9% at ≥7–9 sites. The mean difference between the proportion of pathological CE in patients with and without GCs was 27.4% for synovial sites and 18.3% for periarticular/musculotendinous sites. Both composite scores captured substantial differences between groups, and correlation was very strong between scores. Conclusion: MRI shows CE of musculoskeletal structures typical of PMR in most patients with GCA, supporting the concept of ‘GCA-PMR spectrum disease’. Changes are more frequent at periarticular/musculotendinous sites and in the presence of PMR symptoms. A clear response to GCs is evident, less so for periarticular/musculotendinous sites.

Objectives: Neutrophils play a key role in ANCA-associated vasculitis, both as targets of autoimmunity and as facilitators of vascular damage. In granulomatosis with polyangiitis (GPA), the data regarding the production of reactive oxygen species (ROS) in neutrophils are unclear. Further, recent data suggests that ROS production could have an anti-inflammatory effect through the regulation of inflammasomes and IL-1–related cytokines. We aimed to analyse ROS production in neutrophils from patients with GPA and investigate its association with IL-1–related cytokines and the autoantigen PR3. Methods: Seventy-two GPA patients with disease flare were included in the NEUTROVASC prospective cohort study. ROS production in whole blood of patients with active GPA was evaluated and compared with that in the same patients in remission or healthy controls. Associations between ROS production, PR3 membrane expression on neutrophils, serum levels of IL-1–related cytokines as well as inflammasome-related proteins were analysed. Results: We observed a robust defect in ROS production by neutrophils from patients with active GPA compared with healthy controls, independent of glucocorticoid treatment. Serum levels of IL-1–related cytokines were significantly increased in GPA patients, particularly in patients with kidney involvement, and levels of these cytokines returned to normal after patients achieved remission. Further, inflammasome-related proteins were significantly dysregulated in the cytosol of neutrophils as well as the serum from GPA patients. Conclusion: Our data suggests that ROS production and regulation of inflammasomes in neutrophils from patients with GPA are disturbed and may be a potential therapeutic target. Trial registration: ClinicalTrials.gov, https://www.clinicaltrials.gov, NCT01862068.

Background B-cell depleting therapies increase COVID19 morbidity and mortality. For this specific population, evidence-based vaccination strategies are lacking. Here, we investigated humoral and cell mediated immune responses to SARS-CoV2 mRNA-based vaccines in patients receiving CD20-B-cell depleting agents for autoimmune disease, malignancy, or transplantation. Methods Patients at the Bern University Hospital with a treatment history of anti-CD20 depleting agents (rituximab or ocrelizumab) were enrolled for analysis of humoral and cell-mediated immune responses (by interferon-γ release assay) after completing vaccination against SARS-CoV2. Primary outcome was the the anti-spike antibody response in anti-CD20-treated patients (n=96) in comparison to immunocompetent controls (n=29). Results Anti-spike IgG antibodies were detected in 49% of patients 1.79 months after the second vaccine dose (interquartile range, IQR: 1.16-2.48) compared to 100% of controls (p<0.001). SARS-CoV2 specific interferon-γ release was detected in 20% of patients and 75% of healthy controls (p<0.001). Only 11% of patients, but 75%of healthy controls showed positive reactions in both assays, respectively (p27/µl), and CD4+ lymphocyte count (>653/µl) predicted humoral vaccine response (area under the curve [AUC]: 67% [CI 56-78], 67% [CI 55-80] and 66% [CI 54-79], (positive predictive value [PPV]: 0.78, 0.7 and 0.71). Conclusion This study provides evidence for blunted humoral and cell-mediated immune responses elicited by SARS-CoV2 mRNA vaccines in patients with CD20-depleting treatment history. Lymphocyte subpopulation counts are associated with vaccine response in this highly vulnerable population. (Funded by Bern University Hospital, ClinicalTrials.gov number, NCT04877496)