Neutrophil extracellular traps in giant cell arteritis biopsies: presentation, localization and co-expression with inflammatory cytokines

The role of neutrophil extracellular traps in inflammatory rheumatic diseases

PURPOSE OF REVIEW

Dysregulation in neutrophil extracellular trap (NET) formation and degradation has been reported in several inflammatory rheumatic diseases. This review summarizes the recent advances in the understanding the role of NETs in the context of inflammatory rheumatic diseases.

RECENT FINDINGS

NET formation is enhanced in peripheral blood of patients with large vessel vasculitis and polymyalgia rheumatica. NETs are detected in affected organs in autoimmune conditions, and they might play pathological roles in tissues. Several understudied medications and supplements suppress NET formation and ameliorate animal models of inflammatory rheumatic diseases. NETs and anti-NET antibodies have potential utility as disease biomarkers.

SUMMARY

Growing evidence has suggested the contribution of NET dysregulation to the pathogenesis of several inflammatory rheumatic diseases. Further research is warranted in regard to clinical impact of modulating aberrant NET formation and clearance in inflammatory rheumatic diseases.

Vascular disease persistence in giant cell arteritis: are stromal cells neglected?

Giant cell arteritis (GCA), the most common systemic vasculitis, is characterised by aberrant interactions between infiltrating and resident cells of the vessel wall. Ageing and breach of tolerance are prerequisites for GCA development, resulting in dendritic and T-cell dysfunction. Inflammatory cytokines polarise T-cells, activate resident macrophages and synergistically enhance vascular inflammation, providing a loop of autoreactivity. These events originate in the adventitia, commonly regarded as the biological epicentre of the vessel wall, with additional recruitment of cells that infiltrate and migrate towards the intima. Thus, GCA-vessels exhibit infiltrates across the vascular layers, with various cytokines and growth factors amplifying the pathogenic process. These events activate ineffective repair mechanisms, where dysfunctional vascular smooth muscle cells and fibroblasts phenotypically shift along their lineage and colonise the intima. While high-dose glucocorticoids broadly suppress these inflammatory events, they cause well known deleterious effects. Despite the emerging targeted therapeutics, disease relapse remains common, affecting >50% of patients. This may reflect a discrepancy between systemic and local mediators of inflammation. Indeed, temporal arteries and aortas of GCA-patients can show immune-mediated abnormalities, despite the treatment induced clinical remission. The mechanisms of persistence of vascular disease in GCA remain elusive. Studies in other chronic inflammatory diseases point to the fibroblasts (and their lineage cells including myofibroblasts) as possible orchestrators or even effectors of disease chronicity through interactions with immune cells. Here, we critically review the contribution of immune and stromal cells to GCA pathogenesis and analyse the molecular mechanisms by which these would underpin the persistence of vascular disease.

Risk loci involved in giant cell arteritis susceptibility: a genome-wide association study

BACKGROUND

Giant cell arteritis is an age-related vasculitis that mainly affects the aorta and its branches in individuals aged 50 years and older. Current options for diagnosis and treatment are scarce, highlighting the need to better understand its underlying pathogenesis. Genome-wide association studies (GWAS) have emerged as a powerful tool for unravelling the pathogenic mechanisms involved in complex diseases. We aimed to characterise the genetic basis of giant cell arteritis by performing the largest GWAS of this vasculitis to date and to assess the functional consequences and clinical implications of identified risk loci.

METHODS

We collected and meta-analysed genomic data from patients with giant cell arteritis and healthy controls of European ancestry from ten cohorts across Europe and North America. Eligible patients required confirmation of giant cell arteritis diagnosis by positive temporal artery biopsy, positive temporal artery doppler ultrasonography, or imaging techniques confirming large-vessel vasculitis. We assessed the functional consequences of loci associated with giant cell arteritis using cell enrichment analysis, fine-mapping, and causal gene prioritisation. We also performed a drug repurposing analysis and developed a polygenic risk score to explore the clinical implications of our findings.

FINDINGS

We included a total of 3498 patients with giant cell arteritis and 15 550 controls. We identified three novel loci associated with risk of giant cell arteritis. Two loci, MFGE8 (rs8029053; p=4·96 × 10-8; OR 1·19 [95% CI 1·12-1·26]) and VTN (rs704; p=2·75 × 10-9; OR 0·84 [0·79-0·89]), were related to angiogenesis pathways and the third locus, CCDC25 (rs11782624; p=1·28 × 10-8; OR 1·18 [1·12-1·25]), was related to neutrophil extracellular traps (NETs). We also found an association between this vasculitis and HLA region and PLG. Variants associated with giant cell arteritis seemed to fulfil a specific regulatory role in crucial immune cell types. Furthermore, we identified several drugs that could represent promising candidates for treatment of this disease. The polygenic risk score model was able to identify individuals at increased risk of developing giant cell arteritis (90th percentile OR 2·87 [95% CI 2·15-3·82]; p=1·73 × 10-13).

INTERPRETATION

We have found several additional loci associated with giant cell arteritis, highlighting the crucial role of angiogenesis in disease susceptibility. Our study represents a step forward in the translation of genomic findings to clinical practice in giant cell arteritis, proposing new treatments and a method to measure genetic predisposition to this vasculitis.

FUNDING

Institute of Health Carlos III, Spanish Ministry of Science and Innovation, UK Medical Research Council, and National Institute for Health and Care Research.

Current Insights into Tissue Injury of Giant Cell Arteritis: From Acute Inflammatory Responses towards Inappropriate Tissue Remodeling

Giant cell arteritis (GCA) is an autoimmune disease affecting large vessels in patients over 50 years old. It is an exemplary model of a classic inflammatory disorder with IL-6 playing the leading role. The main comorbidities that may appear acutely or chronically are vascular occlusion leading to blindness and thoracic aorta aneurysm formation, respectively. The tissue inflammatory bulk is expressed as acute or chronic delayed-type hypersensitivity reactions, the latter being apparent by giant cell formation. The activated monocytes/macrophages are associated with pronounced Th1 and Th17 responses. B-cells and neutrophils also participate in the inflammatory lesion. However, the exact order of appearance and mechanistic interactions between cells are hindered by the lack of cellular and molecular information from early disease stages and accurate experimental models. Recently, senescent cells and neutrophil extracellular traps have been described in tissue lesions. These structures can remain in tissues for a prolonged period, potentially favoring inflammatory responses and tissue remodeling. In this review, current advances in GCA pathogenesis are discussed in different inflammatory phases. Through the description of these-often overlapping-phases, cells, molecules, and small lipid mediators with pathogenetic potential are described.

Senescent cells in giant cell arteritis display an inflammatory phenotype participating in tissue injury via IL-6-dependent pathways

OBJECTIVES

Age is the strongest risk factor of giant cell arteritis (GCA), implying a possible pathogenetic role of cellular senescence. To address this question, we applied an established senescence specific multimarker algorithm in temporal artery biopsies (TABs) of GCA patients.

METHODS

75(+) TABs from GCA patients, 22(-) TABs from polymyalgia rheumatica (PMR) patients and 10(-) TABs from non-GCA/non-PMR patients were retrospectively retrieved and analysed. Synovial tissue specimens from patients with inflammatory arthritis and aorta tissue were used as disease control samples. Senescent cells and their histological origin were identified with specific cellular markers; IL-6 and MMP-9 were investigated as components of the senescent associated secretory phenotype by triple costaining. GCA or PMR artery culture supernatants were applied to fibroblasts, HUVECs and monocytes with or without IL-6R blocking agent to explore the induction of IL-6-associated cellular senescence.

RESULTS

Senescent cells were present in GCA arteries at higher proportion compared with PMR (9.50% vs 2.66%, respectively, p<0.0001) and were mainly originated from fibroblasts, macrophages and endothelial cells. IL-6 was expressed by senescent fibroblasts, and macrophages while MMP-9 by senescent fibroblasts only. IL-6(+) senescent cells were associated with the extension of vascular inflammation (transmural inflammation vs adventitia limited disease: 10.02% vs 4.37%, respectively, p<0.0001). GCA but not PMR artery culture supernatant could induce IL-6-associated senescence that was partially inhibited by IL-6R blockade.

CONCLUSIONS

Senescent cells with inflammatory phenotype are present in GCA arteries and are associated with the tissue inflammatory bulk, suggesting a potential implication in disease pathogenesis.

The Contribution of Innate Immunity in Large-Vessel Vasculitis: Detangling New Pathomechanisms beyond the Onset of Vascular Inflammation

Large-vessel vasculitis (LVV) are autoimmune and autoinflammatory diseases focused on vascular inflammation. The central core of the intricate immunological and molecular network resides in the disruption of the "privileged immune state" of the arterial wall. The outbreak, initially primed by dendritic cells (DC), is then continuously powered in a feed-forward loop by the intimate cooperation between innate and adaptive immunity. If the role of adaptive immunity has been largely elucidated, knowledge of the critical function of innate immunity in LVV is still fragile. A growing body of evidence has strengthened the active role of innate immunity players and their key signaling pathways in orchestrating the complex pathomechanisms underlying LVV. Besides DC, macrophages are crucial culprits in LVV development and participate across all phases of vascular inflammation, culminating in vessel wall remodeling. In recent years, the variety of potential pathogenic actors has expanded to include neutrophils, mast cells, and soluble mediators, including the complement system. Interestingly, new insights have recently linked the inflammasome to vascular inflammation, paving the way for its potential pathogenic role in LVV. Overall, these observations encourage a new conceptual approach that includes a more in-depth study of innate immunity pathways in LVV to guide future targeted therapies.

Giant Cell Arteritis: Advances in Understanding Pathogenesis and Implications for Clinical Practice

Giant cell arteritis (GCA) is a noninfectious granulomatous vasculitis of unknown etiology affecting individuals older than 50 years. Two forms of GCA have been identified: a cranial form involving the medium-caliber temporal artery causing temporal arteritis (TA) and an extracranial form involving the large vessels, mainly the thoracic aorta and its branches. GCA generally affects individuals with a genetic predisposition, but several epigenetic (micro)environmental factors are often critical for the onset of this vasculitis. A key role in the pathogenesis of GCA is played by cells of both the innate and adaptive immune systems, which contribute to the formation of granulomas that may include giant cells, a hallmark of the disease, and arterial tertiary follicular organs. Cells of the vessel wall cells, including vascular smooth muscle cells (VSMCs) and endothelial cells, actively contribute to vascular remodeling responsible for vascular stenosis and ischemic complications. This review will discuss new insights into the molecular and cellular pathogenetic mechanisms of GCA, as well as the implications of these findings for the development of new diagnostic biomarkers and targeted drugs that could hopefully replace glucocorticoids (GCs), still the backbone of therapy for this vasculitis.

The IL-17 pathway as a target in giant cell arteritis

The network of IL-17 cytokines is considered a key component of autoimmune and inflammatory processes. Blocking IL-17 showed great success in psoriasis as well as psoriatic arthritis, and in patients with axial spondyloarthritis. Secukinumab is one of the approved IL-17A inhibitors for these diseases and is now routinely used. In giant cell arteritis, a large vessel vasculitis, there is accumulating evidence for a pathogenic role of IL-17 and Th17 cells, which are part of the CD4+ T-cell subset. Giant cell arteritis occurs in individuals over 50 years of age and many have relative contraindications to glucocorticoid therapy, which today still represents the mainstay therapy. Despite the approval of tocilizumab, which targets the IL-6 receptor, a high demand for glucocorticoid-sparing agents remains that combine the effective suppression of the acute inflammation observed in giant cell arteritis with a safety profile that matches the needs of an older patient population. The first results from a phase II proof-of-principle study (TitAIN) support an optimistic outlook on a potential new treatment option with secukinumab in giant cell arteritis.

Single-cell transcriptomic profiling reveals a pathogenic role of cytotoxic CD4+ T cells in giant cell arteritis

Giant cell arteritis (GCA) is a systemic vasculitis mediated by an aberrant immunological response against the blood vessel wall. Although the pathogenic mechanisms that drive GCA have not yet been elucidated, there is strong evidence that CD4+ T cells are key drivers of the inflammatory process occurring in this vasculitis. The aim of this study was to further delineate the role of CD4+ T cells in GCA by applying single-cell RNA sequencing and T cell receptor (TCR) repertoire profiling to 114.799 circulating CD4+ T cells from eight GCA patients in two different clinical states, active and in remission, and eight healthy controls. Our results revealed an expansion of cytotoxic CD4+ T lymphocytes (CTLs) in active GCA patients, which expressed higher levels of cytotoxic and chemotactic genes when compared to patients in remission and controls. Accordingly, differentially expressed genes in CTLs of active patients were enriched in pathways related to granzyme-mediated apoptosis, inflammation, and the recruitment of different immune cells, suggesting a role of this cell type in the inflammatory and vascular remodelling processes occurring in GCA. CTLs also exhibited a higher clonal expansion in active patients with respect to those in remission. Drug repurposing analysis prioritized maraviroc, which targeted CTLs, as potentially repositionable for this vasculitis. In addition, effector regulatory T cells (Tregs) were decreased in GCA and showed lower expression of genes involved in their suppressive activity. These findings provide further insights into the pathogenic role of CD4+ T cells in GCA and suggest targeting CTLs as a potential therapeutic option.

Adventitial Vasa Vasorum Neovascularization in Femoral Artery of Type 2 Diabetic Patients with Macroangiopathy Is Associated with Macrophages and Lymphocytes as well as the Occurrence of Cardiovascular Events

OBJECTIVES

 This study was conducted to assess the relationship between adventitial vasa vasorum neovascularization (VVn) in femoral artery of type 2 diabetic patients with macroangiopathy and the recruitment of macrophages and lymphocytes, and to relate the density of VVn to the occurrence of cardiovascular events.

MATERIALS

 Femoral artery samples were obtained from amputation cases. A total of 55 type 2 diabetic patients with macroangiopathy, 15 autopsy cases with type 2 diabetes without atherosclerosis.

METHODS

 Hematoxylin and eosin (H&E) staining to observe the histopathological features; Victoria blue staining to analyze the histological features; immunohistochemistry (CD34, CD68, CD20, and CD3) to determine the VVn density and the expression of macrophages, B lymphocytes, and T lymphocytes.

RESULTS

 Type 2 diabetic patients with macroangiopathy showed a higher mean adventitial VVn density in femoral artery (48.40 ± 9.39 no./mm2) than patients with type 2 diabetes without atherosclerosis (19.75 ± 6.28 no./mm2) (p < 0.01). In addition, the VVn density was positively associated with the expression of CD68 macrophages (r = 0.62, p < 0.01) and CD20 B lymphocytes (r = 0.59, p < 0.01). Type 2 diabetic patients with high VVn density showed more adverse cardiovascular events (27/35 vs. 8/20 events, p = 0.006). In multivariable analysis adjusted for main risk factors for cardiovascular disease, VVn was still independently associated with adverse cardiovascular events (p = 0.01).

CONCLUSION

 VVn density in type 2 diabetic patients with macroangiopathy is positively correlated with the adventitial immune-inflammatory cell numbers and the development of atherosclerotic lesions. Furthermore, VVn density is associated with adverse cardiovascular events.

Neutrophil extracellular trap formation in anti-neutrophil cytoplasmic antibody-associated and large-vessel vasculitis

Levels of neutrophil extracellular traps (NETs) were measured in plasma of healthy controls (HC, n = 30) and patients with granulomatosis with polyangiitis (GPA, n = 123), microscopic polyangiitis (MPA, n = 61), Takayasu's arteritis (TAK, n = 58), and giant cell arteritis (GCA, n = 68), at times of remission or activity and correlated with levels of the platelet-derived thrombospondin-1 (TSP-1). Levels of NETs were elevated during active disease in patients with GPA (p < 0.0001), MPA (p = 0.0038), TAK (p < 0.0001), and GCA (p < 0.0001), and in remission for GPA, p < 0.0001, MPA, p = 0.005, TAK, p = 0.03, and GCA, p = 0.0009. All cohorts demonstrated impaired NET degradation. Patients with GPA (p = 0.0045) and MPA (p = 0.005) had anti-NET IgG antibodies. Patients with TAK had anti-histone antibodies (p < 0.01), correlating with presence of NETs. Levels of TSP-1 were increased in all patients with vasculitis, and associated with NET formation. NET formation is a common process in vasculitides. Targeting NET formation or degradation could be potential therapeutic approaches for vasculitides.

The role of autoimmunity and autoinflammation in giant cell arteritis: A systematic literature review

Giant cell arteritis is the most common form of large vessel vasculitis and preferentially involves large and medium-sized arteries in patients over the age of 50. Aggressive wall inflammation, neoangiogenesis and consecutive remodeling processes are the hallmark of the disease. Though etiology is unknown, cellular and humoral immunopathological processes are well understood. Matrix metalloproteinase-9 mediated tissue infiltration occurs through lysis of basal membranes in adventitial vessels. CD4+ cells attain residency in immunoprotected niches, differentiate into vasculitogenic effector cells and enforce further leukotaxis. Signaling pathways involve the NOTCH1-Jagged1 pathway opening vessel infiltration, CD28 mediated T-cell overstimulation, lost PD-1/PD-L1 co-inhibition and JAK/STAT signaling in interferon dependent responses. From a humoral perspective, IL-6 represents a classical cytokine and potential Th-cell differentiator whereas interferon-γ (IFN- γ) has been shown to induce chemokine ligands. Current therapies involve glucocorticoids, tocilizumab and methotrexate application. However, new agents, most notably JAK/STAT inhibitors, PD-1 agonists and MMP-9 blocking substances, are being evaluated in ongoing clinical trials.

Immunology of Giant Cell Arteritis

Giant cell arteritis is an autoimmune disease of medium and large arteries, characterized by granulomatous inflammation of the three-layered vessel wall that results in vaso-occlusion, wall dissection, and aneurysm formation. The immunopathogenesis of giant cell arteritis is an accumulative process in which a prolonged asymptomatic period is followed by uncontrolled innate immunity, a breakdown in self-tolerance, the transition of autoimmunity from the periphery into the vessel wall and, eventually, the progressive evolution of vessel wall inflammation. Each of the steps in pathogenesis corresponds to specific immuno-phenotypes that provide mechanistic insights into how the immune system attacks and damages blood vessels. Clinically evident disease begins with inappropriate activation of myeloid cells triggering the release of hepatic acute phase proteins and inducing extravascular manifestations, such as muscle pains and stiffness diagnosed as polymyalgia rheumatica. Loss of self-tolerance in the adaptive immune system is linked to aberrant signaling in the NOTCH pathway, leading to expansion of NOTCH1+CD4+ T cells and the functional decline of NOTCH4+ T regulatory cells (Checkpoint 1). A defect in the endothelial cell barrier of adventitial vasa vasorum networks marks Checkpoint 2; the invasion of monocytes, macrophages and T cells into the arterial wall. Due to the failure of the immuno-inhibitory PD-1 (programmed cell death protein 1)/PD-L1 (programmed cell death ligand 1) pathway, wall-infiltrating immune cells arrive in a permissive tissues microenvironment, where multiple T cell effector lineages thrive, shift toward high glycolytic activity, and support the development of tissue-damaging macrophages, including multinucleated giant cells (Checkpoint 3). Eventually, the vascular lesions are occupied by self-renewing T cells that provide autonomy to the disease process and limit the therapeutic effectiveness of currently used immunosuppressants. The multi-step process deviating protective to pathogenic immunity offers an array of interception points that provide opportunities for the prevention and therapeutic management of this devastating autoimmune disease.

Changes in the molecular profiles of large-vessel vasculitis treated with biological disease-modifying anti-rheumatic drugs and Janus kinase inhibitors

Giant cell arteritis and Takayasu arteritis are two types of primary large-vessel vasculitis (LVV). Although glucocorticoids (GC) are the standard treatment for LVV, the disease relapse rates are high. Recent clinical trials on biological disease-modifying anti-rheumatic drugs (bDMARDs) and Janus kinase (JAK) inhibitors have demonstrated their efficacy in reducing LVV relapse rates and GC dosages. However, the control of residual inflammation and degenerative alterations in the vessel wall remains an outstanding requirement in the clinical management of LVV. The analysis of immune cell phenotypes in patients with LVV may predict their response to treatment with bDMARDs and JAK inhibitors and guide their optimal use. In this mini-review, we focused on molecular markers, including the immune cell proportions and gene expression, in patients with LVV and in mouse models of LVV treated with bDMARDs and JAK inhibitors.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

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.

Pathogenesis of giant cell arteritis with focus on cellular populations

Giant cell arteritis (GCA), the most common non-infectious vasculitis, mainly affects elderly individuals. The disease usually affects the aorta and its main supra-aortic branches causing both general symptoms of inflammation and specific ischemic symptoms because of the limited blood flow due to arterial structural changes in the inflamed arteries. The pathogenesis of the GCA is complex and includes a dysregulated immune response that affects both the innate and the adaptive immunity. During the last two decades several studies have investigated interactions among antigen-presenting cells and lymphocytes, which contribute to the formation of the inflammatory infiltrate in the affected arteries. Toll-like receptor signaling and interactions through the VEGF-Notch-Jagged1 pathway are emerging as crucial events of the aberrant inflammatory response, facilitating among others the migration of inflammatory cells to the inflamed arteries and their interactions with the local stromal milieu. The increased use of checkpoint inhibitors in cancer immunotherapy and their immune-related adverse events has fed interest in the role of checkpoint dysfunction in GCA, and recent studies suggest a dysregulated check point system which is unable to suppress the inflammation in the previously immune-privileged arteries, leading to vasculitis. The role of B-cells is currently reevaluated because of new reports of considerable numbers of plasma cells in inflamed arteries as well as the formation of artery tertiary lymphoid organs. There is emerging evidence on previously less studied cell populations, such as the neutrophils, CD8+ T-cells, T regulatory cells and tissue residing memory cells as well as for stromal cells which were previously considered as innocent bystanders. The aim of this review is to summarize the evidence in the literature regarding the cell populations involved in the pathogenesis of GCA and especially in the context of an aged, immune system.

Longitudinal monitoring of circulating immune cell phenotypes in large vessel vasculitis

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are two types of primary large vessel vasculitis (LVV). LVV is an intractable, rare disease with a high relapse rate. Disease progression in asymptomatic patients is an important issue in the clinical management of LVV. Useful biomarkers associated with clinical phenotypes, disease activity, and prognosis may be present in peripheral blood. In this review, we focused on peripheral leukocyte counts, surface markers, functions, and gene expression in LVV patients. In particular, we explored longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and during treatment. The numbers and phenotypes of leukocytes in the peripheral blood were different between LVV and healthy controls, GCA and TAK, LVV in active versus treatment phases, and LVV in treatment responders versus non-responders. Therefore, biomarkers obtained from peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in LVV.

The role of neutrophils in rheumatic disease-associated vascular inflammation

Vascular pathologies underpin and intertwine autoimmune rheumatic diseases and cardiovascular conditions, and atherosclerosis is increasingly recognized as the leading cause of morbidity in conditions such as systemic lupus erythematosus (SLE), rheumatoid arthritis and antineutrophil cytoplasmic antibody-associated vasculitis. Neutrophils, important cells in the innate immune system, exert their functional effects in tissues via a variety of mechanisms, including the generation of neutrophil extracellular traps and the production of reactive oxygen species. Neutrophils have been implicated in the pathogenesis of several rheumatic diseases, and can also intimately interact with the vascular system, either through modulating endothelial barriers at the blood-vessel interface, or through associations with platelets. Emerging data suggest that neutrophils also have an important role maintaining homeostasis in individual organs and can protect the vascular system. Furthermore, studies using high-dimensional omics technologies have advanced our understanding of neutrophil diversity, and immature neutrophils are receiving new attention in rheumatic diseases including SLE and systemic vasculitis. Developments in genomic, imaging and organoid technologies are beginning to enable more in-depth investigations into the pathophysiology of vascular inflammation in rheumatic diseases, making now a good time to re-examine the full scope of roles of neutrophils in these processes.