An expanded population of pathogenic regulatory T cells in giant cell arteritis is abrogated by IL-6 blockade therapy

Steroid-Refractory Myocarditis Induced by Immune Checkpoint Inhibitor Responded to Infliximab: Report of Two Cases and Literature Review

Immune checkpoint inhibitors (ICIs), including anti-programmed cell death protein 1 and its ligand (PD-1/PD-L1) as well as anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4), have been widely used for treating solid tumors. Myocarditis is a potentially lethal immune-related adverse events (irAEs) caused by ICIs therapy. The treatment of steroid-refractory myocarditis is challenging. We reported two non-small-cell lung cancer patients with steroid-refractory myocarditis induced by ICI. The symptoms were not resolved after pulse corticosteroid therapy and subsequent treatment including intravenous immunoglobulin and mycophenolate mofetil. Considering the level of serum interleukin (IL)-6 decreased by > 50% and level of serum tumor necrosis factor-α (TNF-α) increased during the course of the disease, infliximab was used. Myocarditis gradually alleviated after infliximab treatment. The cases revealed that specific cytokine inhibitors have promising roles in the treatment of steroid-refractory myocarditis. Infliximab could be considered for patients with low level of IL-6 and elevated level of TNF-α.

Effects of interleukin-6 signal inhibition on Treg subpopulations and association of Tregs with clinical outcomes in rheumatoid arthritis

OBJECTIVES

Anti-IL-6 receptor antibodies are clinically efficacious in the management of RA with an associated increase in Tregs; however, the role of functional Treg subsets has yet to be clarified. This study aimed to evaluate how functional Treg subsets are altered by IL-6 receptor blockade and to analyse the relationship between these Treg subsets and the clinical outcome of RA.

METHODS

We collected frozen peripheral blood mononuclear cells (PBMCs) from 40 patients with RA who started tocilizumab (TCZ) with or without MTX and 11 healthy controls (HCs). We fractionated Tregs with flow cytometry based on markers of phenotype and function and measured the proportions of detailed Treg subsets sequentially from baseline to week 52.

RESULTS

The proportions of resting Tregs (rTregs) and rTregs+activated Tregs (aTregs) were significantly lower in RA patients at baseline than in HCs. The proportions of all those CD127low Tregs, rTregs, aTregs and rTregs+aTregs were significantly increased with TCZ treatment. In patients treated with TCZ without MTX, rTreg were increased. Patients with an increase in the proportion of rTregs at week 12 had significantly less arthritis flares during the observation period.

CONCLUSIONS

Blocking the IL-6 receptor with TCZ increased the proportion of rTregs, a functional Treg subpopulation. Patients with an early increase in rTregs showed a favourable treatment course and this increase in rTregs may reflect molecular remission induced by IL-6 signal inhibition.

Effectiveness of janus kinase inhibitors in relapsing giant cell arteritis in real-world clinical practice and review of the literature

BACKGROUND

A substantial proportion of patients with giant cell arteritis (GCA) relapse despite standard therapy with glucocorticoids, methotrexate and tocilizumab. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway is involved in the pathogenesis of GCA and JAK inhibitors (JAKi) could be a therapeutic alternative. We evaluated the effectiveness of JAKi in relapsing GCA patients in a real-world setting and reviewed available literature.

METHODS

Retrospective analysis of GCA patients treated with JAKi for relapsing disease at thirteen centers in Spain and one center in United States (01/2017-12/2022). Outcomes assessed included clinical remission, complete remission and safety. Clinical remission was defined as the absence of GCA signs and symptoms regardless of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values. Complete remission was defined as the absence of GCA signs and symptoms along with normal ESR and CRP values. A systematic literature search for other JAKi-treated GCA cases was conducted.

RESULTS

Thirty-five patients (86% females, mean age 72.3) with relapsing GCA received JAKi therapy (baricitinib, n = 15; tofacitinib, n = 10; upadacitinib, n = 10). Before JAKi therapy, 22 (63%) patients had received conventional synthetic immunosuppressants (e.g., methotrexate), and 30 (86%) biologics (e.g., tocilizumab). After a median (IQR) follow-up of 11 (6-15.5) months, 20 (57%) patients achieved and maintained clinical remission, 16 (46%) patients achieved and maintained complete remission, and 15 (43%) patients discontinued the initial JAKi due to relapse (n = 11 [31%]) or serious adverse events (n = 4 [11%]). A literature search identified another 36 JAKi-treated GCA cases with clinical improvement reported for the majority of them.

CONCLUSIONS

This real-world analysis and literature review suggest that JAKi could be effective in GCA, including in patients failing established glucocorticoid-sparing therapies such as tocilizumab and methotrexate. A phase III randomized controlled trial of upadacitinib is currently ongoing (ClinicalTrials.gov ID NCT03725202).

Cranial involvement in giant cell arteritis

Since its first clinical description in 1890, extensive research has advanced our understanding of giant cell arteritis, leading to improvements in both diagnosis and management for affected patients. Imaging studies have shown that the disease frequently extends beyond the typical cranial arteries, also affecting large vessels such as the aorta and its proximal branches. Meanwhile, advances in comprehending the underlying pathophysiology of giant cell arteritis have given rise to numerous potential therapeutic agents, which aim to minimise the need for glucocorticoid treatment and prevent flares. Classification criteria for giant cell arteritis, as well as recommendations for management, imaging, and treat-to-target have been developed or updated in the last 5 years, and current research encompasses a broad spectrum covering basic, translational, and clinical research. In this Series paper, we aim to discuss the current understanding of giant cell arteritis with cranial manifestations, describe the clinical approach to this condition, and explore future directions in research and patient care.

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.

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.

Metabolic regulation of forkhead box P3 alternative splicing isoforms and their impact on health and disease

Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs.

Giant Cell Arteritis and Polymyalgia Rheumatica: Treatment Approaches and New Targets

Prolonged glucocorticoid tapers have been the standard of care for giant cell arteritis (GCA) and polymyalgia rheumatica (PMR), but recent advancements have improved outcomes for patients with GCA while reducing glucocorticoid-related toxicities. Many patients with GCA and PMR still experience persistent or relapsing disease, and cumulative exposure to glucocorticoids for both diseases remains high. The objective of this review is to define current treatment approaches as well as new therapeutic targets and strategies. Studies investigating inhibition of cytokine pathways, including interleukin-6, interleukin-17, interleukin-23, granulocyte-macrophage colony-stimulating factor, Janus kinase-signal transduction and activator of transcription, and others, will be reviewed.

Biomarkers in the era of targeted therapy in giant cell arteritis and polymyalgia rheumatica: is it possible to replace acute-phase reactants?

Research into giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) has become more important in the last few decades. Physicians are facing several challenges in managing the diagnosis, treatment, and relapses of GCA and PMR patients. The search for biomarkers could provide elements to guide a physician's decision. In this review, we aim to summarize the scientific publications about biomarkers in GCA and PMR in the past decade. The first point raised by this review is the number of clinical situations in which biomarkers could be useful: differential diagnosis of either GCA or PMR, diagnosis of underlying vasculitis in PMR, prediction of relapse or complications, disease activity monitoring, choice, and modification of treatments. The second point raised by this review is the large number of biomarkers studied, from common markers like C-reactive protein, erythrocyte sedimentation rate, or elements of blood count to inflammatory cytokines, growth factors, or immune cell subpopulations. Finally, this review underlines the heterogeneity between the studies and proposes points to consider in studies evaluating biomarkers in general and particularly in the case of GCA and PMR.

Safety and efficacy of secukinumab in patients with giant cell arteritis (TitAIN): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

The treatment of giant cell arteritis with glucocorticoid-sparing agents is an unmet medical need. We evaluated the efficacy and safety of secukinumab, an anti-interleukin-17A monoclonal antibody, in patients with giant cell arteritis.

METHODS

We conducted a Bayesian randomised, parallel-group, double-blind, placebo-controlled, multicentre, phase 2 study at 11 clinics or hospitals in Germany. Patients aged 50 years or older with new-onset or relapsing giant cell arteritis who were naive to biological therapy and already receiving glucocorticoids with a prednisolone equivalent dose of 25-60 mg/day were eligible for inclusion. Participants were assigned (1:1) to receive 300 mg secukinumab or placebo subcutaneously once a week up to week 4 and every 4 weeks thereafter. In both treatment groups, prednisolone dose was tapered down to 0 mg over a 26-week period. Patients, investigator staff, and clinical trial team were masked to the treatment assignment. The primary endpoint was the median proportion (Bayesian analysis) of patients with sustained remission until week 28 in the full analysis set (ie, all patients who received at least one dose of assigned treatment, analysed according to treatment assigned at randomisation). Sustained remission rate of the placebo group from a previous trial of tocilizumab in patients with giant cell arteritis was used to derive the prior distribution of placebo sustained remission rate for the primary endpoint. The safety of secukinumab was assessed in the safety set (ie, all patients who received at least one dose of study treatment, analysed according to study treatment received). This trial is completed and is registered with ClinicalTrials.gov, NCT03765788.

FINDINGS

Of the 65 patients who were assessed for eligibility, 52 patients (median age 75 years [IQR 69-79]; 35 [67%] female and 17 [33%] male, 52 [100%] White) were enrolled between Jan 30, 2019 and March 30, 2020 and were randomly assigned to receive secukinumab (n=27) or placebo (n=25). Four of 27 patients in the secukinumab group and eight of 25 patients in the placebo group discontinued treatment by week 28 of the study. On the basis of the Bayesian analysis, the median proportion of patients in sustained remission until week 28 was 70% (95% credibility interval 52-85) in the secukinumab group versus 20% (12-30) in the placebo group. The incidence of adverse events was similar in the secukinumab (27 [100%] of 27 patients had any adverse event) and placebo groups (24 [96%] of 25 patients had any adverse event); the most common adverse events were hypertension (six [22%] of 27 patients in the secukinumab group and eight [32%] of 25 patients in the placebo group) and nasopharyngitis (five [19%] of 27 patients in the secukinumab group and five [20%] of 25 patients in the placebo group). Two patients (one in each group) died during the study, neither of which was considered to be related to study treatment.

INTERPRETATION

Patients with active giant cell arteritis had a higher sustained remission rate in the secukinumab group than in the placebo group at week 28, in combination with glucocorticoid taper regimen. Secukinumab was tolerated well with no new safety concerns. This proof-of-concept phase 2 study further supports the development of secukinumab as a treatment option for people with giant cell arteritis.

FUNDING

Novartis Pharma.

Perspective for Discovery of Small Molecule IL-6 Inhibitors through Study of Structure–Activity Relationships and Molecular Docking

Interleukin-6 (IL-6) is a proinflammatory cytokine that plays a key role in the pathogenesis and physiology of inflammatory and autoimmune diseases, such as coronary heart disease, cancer, Alzheimer's disease, asthma, rheumatoid arthritis, and most recently COVID-19. IL-6 and its signaling pathway are promising targets in the treatment of inflammatory and autoimmune diseases. Although, anti-IL-6 monoclonal antibodies are currently being used in clinics, huge unmet medical needs remain because of the high cost, administration-related toxicity, lack of opportunity for oral dosing, and potential immunogenicity of monoclonal antibody therapy. Furthermore, nonresponse or loss of response to monoclonal antibody therapy has been reported, which increases the importance of optimizing drug therapy with small molecule drugs. This work aims to provide a perspective for the discovery of novel small molecule IL-6 inhibitors by the analysis of the structure-activity relationships and computational studies for protein-protein inhibitors targeting the IL-6/IL-6 receptor/gp130 complex.

CD8+ Regulatory T Cell Deficiency in Elderly-Onset Rheumatoid Arthritis

Elderly-onset rheumatoid arthritis (EORA) is associated with higher disease activity and accelerated joint destruction compared with young-onset RA (YORA). However, the underlying immunological mechanism remains unclear. Regulatory T cells (Tregs) are an immunosuppressive T cell subset, and CD4+ Tregs are deficient and/or dysfunctional in RA; however, CD8+ Tregs have not been fully examined in RA. Here, we aimed to determine the role of CD8+ Tregs, particularly in EORA. A total of 40 patients (EORA, n = 17; YORA, n = 23) were cross-sectionally enrolled. Current disease activity and treatment were comparable between the two groups; however, levels of multiple cytokines, including IL-1β, TNFα, interferon (IFN)-γ, IL-2, and IL-10, were significantly increased in EORA. The number of CD4+ Tregs did not differ between the groups (p = 0.37), but those of CD8+ Tregs were significantly decreased in EORA (p = 0.0033). The number of CD8+ Tregs were inversely correlated with plasma matrix metalloprotease (MMP)-3 levels (r = -0.3331, p = 0.036). Our study results revealed an intrinsic deficiency of CD8+ Tregs in patients with EORA, which leaves synovitis unchecked with excessive MMP-3 release. A therapeutic approach to restore CD8+ Tregs may provide a new avenue for the treatment of EORA.

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.

Role of Peripheral Regulatory T Lymphocytes in Patients with Thyroid Associated Ophthalmopathy During Systemic Glucocorticoid Treatment: A Prospective Observational Study

OBJECTIVE

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disorder involving the orbital tissue. This study aimed to understand the role of regulatory T cells (Tregs) in TAO during 12-week systemic glucocorticoid (GC) treatment.

METHODS

Thirty-two moderate-severe TAO patients with a clinical activity score (CAS) ≥3/7 or with prolonged T2 relaxation time (T2RT) on at least one side of extraocular muscle (EOM) were enrolled. The percentage of the peripheral CD4⁺CD25(high)CD127(-/low) Tregs was analyzed using flow cytometry before and after the GC treatment. The activity and severity of TAO, T2RT, and the clinical outcomes after the GC treatment were assessed. Their correlation with the peripheral Tregs was investigated.

RESULTS

There was no significant association between the baseline Treg fraction and the activity and severity of TAO or the treatment response. A significant reduction of Tregs was observed after the GC therapy merely in patients without any clinical improvement.

CONCLUSION

Treg reduction after systemic GC therapy is indicative of a poor therapeutic response. Accordingly, dynamic alterations of Tregs could help to evaluate the effectiveness of the GC treatment.

Distinct gene signatures of monocytes and B cells in patients with giant cell arteritis: a longitudinal transcriptome analysis

BACKGROUND

Giant cell arteritis (GCA) is a primary large-vessel vasculitis (LVV) of unknown origin. Its management is a challenge due to the late onset of disease symptoms and frequent relapse; therefore, clarifying the pathophysiology of GCA is essential to improving treatment. This study aimed to identify the transition of molecular signatures in immune cells relevant to GCA pathogenesis by analyzing longitudinal transcriptome data in patients.

METHODS

We analyzed the whole blood transcriptome of treatment-naive patients with GCA, patients with Takayasu arteritis (TAK), age-matched, old healthy controls (HCs), and young HCs. Characteristic genes for GCA were identified, and the longitudinal transition of those genes was analyzed using cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT).

RESULTS

Repeated measures analysis of variance revealed 739 differentially expressed genes among all patients and HCs. Of the 739 genes, 15 were characteristically upregulated and 36 were downregulated in patients with GCA compared to those with TAK and HCs. Pathway enrichment analysis showed that downregulated genes in GCA were associated with B cell activation. CIBERSORT analysis revealed that upregulation of "M0-macrophages" and downregulation of B cells were characteristic of GCA. Upregulation of "M0-macrophages" reflects the activation of monocytes in GCA toward M0-like phenotypes, which persisted under 6 weeks of treatment. Combined treatment with prednisolone and an interleukin-6 receptor antagonist normalized molecular profiles more efficiently than prednisolone monotherapy.

CONCLUSIONS

Gene signatures of monocyte activation and B cell inactivation were characteristic of GCA and associated with treatment response.

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.

Regulatory T cells and systemic vasculitis

PURPOSE OF THE REVIEW

Emerging data suggest that regulatory T-cells (Treg) alterations play a major role in systemic vasculitis pathophysiology. We performed a systematic review of recent advances in the role of Treg and interleukin (IL)-10 in the pathogenesis and treatment of systemic vasculitis, including giant cell arteritis (GCA), Takayasu arteritis, Behçet's disease, antineutrophil cytoplasm antibodies (ANCA) associated vasculitis (AAV), and cryoglobulinemia associated vasculitis.

RECENT FINDINGS

Emerging data suggest that Treg deficiencies are disease-specific, affecting distinct pathways in distinct vasculitides. Decreased peripheral blood frequencies of Treg are described in all vasculitis when compared to healthy donors. Altered Treg functions are reported in GCA, Takayasu arteritis, AAV, and Behçet's disease with different mechanisms proposed. Treatment with biologics, and sometimes other immunosuppressants, may restore Treg frequencies and/or immune activity with significant differences in active disease or disease in remission in several systemic vasculitis. IL-10 is elevated in GCA, AAV, cryoglobulinemia associated vasculitis. In Behçet's disease, IL-10 is decreased in peripheral blood and elevated in saliva. In Takayasu arteritis, IL-10 levels were essentially elevated in patients' vessel wall. Several new therapeutic approaches targeting Treg and Il-10 (low dose IL-2, CAR Treg…) are developed to treat patients with systemic vasculitis.

SUMMARY

Treg and IL-10 play a central role in the regulation of inflammation in vasculitis and new targeting approaches are emerging.

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.

Inflammatory Diseases of the Aorta: JACC Focus Seminar, Part 2

Inflammatory aortitis is most often caused by large vessel vasculitis (LVV), including giant cell arteritis, Takayasu's arteritis, immunoglobulin G4-related aortitis, and isolated aortitis. There are distinct differences in the clinical presentation, imaging findings, and natural history of LVV that are important for the cardiovascular provider to know. If possible, histopathologic specimens should be obtained to aide in accurate diagnosis and management of LVV. In most cases, corticosteroids are utilized in the acute phase, with the addition of steroid-sparing agents to achieve disease remission while sparing corticosteroid toxic effects. Endovascular and surgical procedures have been described with success but should be delayed until disease control is achieved whenever possible. Long-term management should include regular follow-up with rheumatology and surveillance imaging for sequelae of LVV.

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.

Pathogenic role of monocytes/macrophages in large vessel vasculitis

Vasculitis is an autoimmune vascular inflammation with an unknown etiology and causes vessel wall destruction. Depending on the size of the blood vessels, it is classified as large, medium, and small vessel vasculitis. A wide variety of immune cells are involved in the pathogenesis of vasculitis. Among these immune cells, monocytes and macrophages are functionally characterized by their capacity for phagocytosis, antigen presentation, and cytokine/chemokine production. After a long debate, recent technological advances have revealed the cellular origin of tissue macrophages in the vessel wall. Tissue macrophages are mainly derived from embryonic progenitor cells under homeostatic conditions, whereas bone marrow-derived circulating monocytes are recruited under inflammatory conditions, and then differentiate into macrophages in the arterial wall. Such macrophages infiltrate into an otherwise immunoprotected vascular site, digest tissue matrix with abundant proteolytic enzymes, and further recruit inflammatory cells through cytokine/chemokine production. In this way, macrophages amplify the inflammatory cascade and eventually cause tissue destruction. Recent studies have also demonstrated that monocytes/macrophages can be divided into several subpopulations based on the cell surface markers and gene expression. In this review, the subpopulations of circulating monocytes and the ontogeny of tissue macrophages in the artery are discussed. We also update the immunopathology of large vessel vasculitis, with a special focus on giant cell arteritis, and outline how monocytes/macrophages participate in the disease process of vascular inflammation. Finally, we discuss limitations of the current research and provide future research perspectives, particularly in humans. Through these processes, we explore the possibility of therapeutic strategies targeting monocytes/macrophages in vasculitis.

FOXP3 exon 2 controls Treg stability and autoimmunity

Differing from the mouse Foxp3 gene that encodes only one protein product, human FOXP3 encodes two major isoforms through alternative splicing-a longer isoform (FOXP3 FL) containing all the coding exons and a shorter isoform lacking the amino acids encoded by exon 2 (FOXP3 ΔE2). The two isoforms are naturally expressed in humans, yet their differences in controlling regulatory T cell phenotype and functionality remain unclear. In this study, we show that patients expressing only the shorter isoform fail to maintain self-tolerance and develop immunodeficiency, polyendocrinopathy, and enteropathy X-linked (IPEX) syndrome. Mice with Foxp3 exon 2 deletion have excessive follicular helper T (TFH) and germinal center B (GC B) cell responses, and develop systemic autoimmune disease with anti-dsDNA and antinuclear autoantibody production, as well as immune complex glomerulonephritis. Despite having normal suppressive function in in vitro assays, regulatory T cells expressing FOXP3 ΔE2 are unstable and sufficient to induce autoimmunity when transferred into Tcrb-deficient mice. Mechanistically, the FOXP3 ΔE2 isoform allows increased expression of selected cytokines, but decreased expression of a set of positive regulators of Foxp3 without altered binding to these gene loci. These findings uncover indispensable functions of the FOXP3 exon 2 region, highlighting a role in regulating a transcriptional program that maintains Treg stability and immune homeostasis.

Vasculitogenic T Cells in Large Vessel Vasculitis

Vasculitis is an autoimmune disease of unknown etiology that causes inflammation of the blood vessels. Large vessel vasculitis is classified as either giant cell arteritis (GCA), which occurs exclusively in the elderly, or Takayasu arteritis (TAK), which mainly affects young women. Various cell types are involved in the pathogenesis of large vessel vasculitis. Among these, dendritic cells located between the adventitia and the media initiate the inflammatory cascade as antigen-presenting cells, followed by activation of macrophages and T cells contributing to vessel wall destruction. In both diseases, naive CD4⁺ T cells are polarized to differentiate into Th1 or Th17 cells, whereas differentiation into regulatory T cells, which suppress vascular inflammation, is inhibited. Skewed T cell differentiation is the result of aberrant intracellular signaling, such as the mechanistic target of rapamycin (mTOR) or the Janus kinase signal transducer and activator of transcription (JAK-STAT) pathways. It has also become clear that tissue niches in the vasculature fuel activated T cells and maintain tissue-resident memory T cells. In this review, we outline the most recent understanding of the pathophysiology of large vessel vasculitis. Then, we provide a summary of skewed T cell differentiation in the vasculature and peripheral blood. Finally, new therapeutic strategies for correcting skewed T cell differentiation as well as aberrant intracellular signaling are discussed.

Does Tocilizumab Influence Ophthalmic Outcomes in Giant Cell Arteritis?

BACKGROUND

Despite appropriate use of corticosteroids, an important minority of patients with giant cell arteritis (GCA) develop progressive vision loss during the initial stages of the disease or during corticosteroid tapering. Tocilizumab is the only clearly effective adjunctive treatment to corticosteroids in the management of GCA, but questions regarding its efficacy specifically in the neuro-ophthalmic population and its role in mitigating vision loss have not been broached until recently.

EVIDENCE ACQUISITION

The authors queried Pubmed using the search terms "GCA" and "tocilizumab" in order to identify English-language publications either explicitly designed to evaluate the influence of tocilizumab on the ophthalmic manifestations of GCA or those which reported, but were not primarily focused on, ophthalmic outcomes.

RESULTS

Recent retrospective analyses of populations similar to those encountered in neuro-ophthalmic practice suggest that tocilizumab is effective in decreasing the frequency of GCA relapse, the proportion of flares involving visual manifestations of GCA, and the likelihood of permanent vision loss. Data regarding the utility of tocilizumab to curtail vision loss at the time of diagnosis are limited to case reports.

CONCLUSIONS

Compared with conventional corticosteroid monotherapy, treatment of GCA with both corticosteroids and tocilizumab may decrease the likelihood of permanent vision loss. Further prospective, collaborative investigation between rheumatologists and neuro-ophthalmologists is required to clarify the ophthalmic and socioeconomic impact of tocilizumab on the treatment of GCA.

New Insights into the Pathogenesis of Giant Cell Arteritis: Mechanisms Involved in Maintaining Vascular Inflammation

The giant cell arteritis (GCA) pathophysiology is complex and multifactorial, involving a predisposing genetic background, the role of immune aging and the activation of vascular dendritic cells by an unknown trigger. Once activated, dendritic cells recruit CD4 T cells and induce their activation, proliferation and polarization into Th1 and Th17, which produce interferon-gamma (IFN-γ) and interleukin-17 (IL-17), respectively. IFN-γ triggers the production of chemokines by vascular smooth muscle cells, which leads to the recruitment of additional CD4 and CD8 T cells and also monocytes that differentiate into macrophages. Recent data have shown that IL-17, IFN-γ and GM-CSF induce the differentiation of macrophage subpopulations, which play a role in the destruction of the arterial wall, in neoangiogenesis or intimal hyperplasia. Under the influence of different mediators, mainly endothelin-1 and PDGF, vascular smooth muscle cells migrate to the intima, proliferate and change their phenotype to become myofibroblasts that further proliferate and produce extracellular matrix proteins, increasing the vascular stenosis. In addition, several defects in the immune regulatory mechanisms probably contribute to chronic vascular inflammation in GCA: a defect in the PD-1/PD-L1 pathway, a quantitative and qualitative Treg deficiency, the implication of resident cells, the role of GM-CSF and IL-6, the implication of the NOTCH pathway and the role of mucosal‑associated invariant T cells and tissue‑resident memory T cells.

Rho Kinase Expression in Giant Cell Arteritis: Validating pERM Intensity Score to Increase Sensitivity of Temporal Artery Biopsy

Objective

Aberrant rho-kinase (ROCK) activity is implicated in several vascular and immunologic disorders. We previously demonstrated increased ROCK activity in histopathologically negative temporal artery biopsies (TAB) in subjects with clinical Giant Cell Arteritis (GCA) compared to those without GCA. This current study aimed to examine ROCK activity in a larger cohort of biopsy-negative GCA subjects and to validate the prior findings.

Methods

Subjects were categorized into 2 groups based on clinical data 6-months after TAB: biopsy-negative GCA and controls without GCA. Paraffin-embedded TAB were stained for phosphorylated ezrin/radixin/moesin (pERM), a surrogate of ROCK activity, and scored by two pathologists blinded to clinical diagnosis using a previously derived scoring system measuring staining intensity in three areas of the vessel

Results

36 subjects with biopsy-negative GCA and 43 controls were analyzed. The mean pERM intensity score in non-GCA subjects was 3.9 – 1.4 (compared to 5.0 – 1.4 in those with GCA, p = 0.002). Using the predetermined cut-off of 4 to define high pERM intensity, subjects with GCA were significantly more likely to have a high pERM intensity score compared to non-GCA, OR 3.67, 95%CI :1.19,11.36; p= 0.019. The sensitivity of high pERM intensity score for diagnosis of GCA in histologically negative TAB was 86%, 95%CI: 70,95.

Conclusion

In this well-characterized cohort, those with biopsy-negative GCA had significantly higher pERM intensity scores compared to subjects without GCA. pERM staining has diagnostic significance in enhancing the sensitivity of TAB, and may help to define the clinically important group of biopsynegative GCA.

The Th17 Pathway in Vascular Inflammation: Culprit or Consort?

The involvement of IL-17A in autoimmune and inflammatory diseases has prompted the development of therapeutic strategies to block the Th17 pathway. Promising results came from their use in psoriasis and in ankylosing spondylitis. IL-17A acts on various cell types and has both local and systemic effects. Considering the premature mortality observed during chronic inflammatory diseases, IL-17A action on vascular cells was studied. Both in vitro and in vivo results suggest that this cytokine favors inflammation, coagulation and thrombosis and promotes the occurrence of cardiovascular events. These observations led to study the role of IL-17A in diseases characterized by vascular inflammation, namely allograft rejection and vasculitis. Increased circulating levels of IL-17A and histological staining reveal that the Th17 pathway is involved in the pathogenesis of these diseases. Vasculitis treatment faces challenges while the use of steroids has many side effects. Regarding results obtained in giant cell arteritis with IL-6 inhibitors, a cytokine involved in Th17 differentiation, the use of anti-IL-17 is a promising strategy. However, lessons from rheumatoid arthritis and multiple sclerosis must be learnt before targeting IL-17 in vasculitis, which may be culprit, consort or both of them.

Large-vessel vasculitis

Large-vessel vasculitis (LVV) manifests as inflammation of the aorta and its major branches and is the most common primary vasculitis in adults. LVV comprises two distinct conditions, giant cell arteritis and Takayasu arteritis, although the phenotypic spectrum of primary LVV is complex. Non-specific symptoms often predominate and so patients with LVV present to a range of health-care providers and settings. Rapid diagnosis, specialist referral and early treatment are key to good patient outcomes. Unfortunately, disease relapse remains common and chronic vascular complications are a source of considerable morbidity. Although accurate monitoring of disease activity is challenging, progress in vascular imaging techniques and the measurement of laboratory biomarkers may facilitate better matching of treatment intensity with disease activity. Further, advances in our understanding of disease pathophysiology have paved the way for novel biologic treatments that target important mediators of disease in both giant cell arteritis and Takayasu arteritis. This work has highlighted the substantial heterogeneity present within LVV and the importance of an individualized therapeutic approach. Future work will focus on understanding the mechanisms of persisting vascular inflammation, which will inform the development of increasingly sophisticated imaging technologies. Together, these will enable better disease prognostication, limit treatment-associated adverse effects, and facilitate targeted development and use of novel therapies.

Novel aspects of regulatory T cell dysfunction as a therapeutic target in giant cell arteritis

OBJECTIVES

Giant cell arteritis (GCA) is the most common primary vasculitis, preferentially affecting the aorta and its large-calibre branches. An imbalance between proinflammatory CD4+ T helper cell subsets and regulatory T cells (Tregs) is thought to be involved in the pathogenesis of GCA and Treg dysfunction has been associated with active disease. Our work aims to explore the aetiology of Treg dysfunction and the way it is affected by remission-inducing immunomodulatory regimens.

METHODS

A total of 41 GCA patients were classified into active disease (n=14) and disease in remission (n=27). GCA patients' and healthy blood donors' (HD) Tregs were sorted and subjected to transcriptome and phenotypic analysis.

RESULTS

Transcriptome analysis revealed 27 genes, which were differentially regulated between GCA-derived and HD-derived Tregs. Among those, we identified transcription factors, glycolytic enzymes and IL-2 signalling mediators. We confirmed the downregulation of forkhead box P3 (FOXP3) and interferon regulatory factor 4 (IRF4) at protein level and identified the ineffective induction of glycoprotein A repetitions predominant (GARP) and CD25 as well as the reduced T cell receptor (TCR)-induced calcium influx as correlates of Treg dysfunction in GCA. Inhibition of glycolysis in HD-derived Tregs recapitulated most identified dysfunctions of GCA Tregs, suggesting the central pathogenic role of the downregulation of the glycolytic enzymes. Separate analysis of the subgroup of tocilizumab-treated patients identified the recovery of the TCR-induced calcium influx and the Treg suppressive function to associate with disease remission.

CONCLUSIONS

Our findings suggest that low glycolysis and calcium signalling account for Treg dysfunction and inflammation in GCA.

Age as a risk factor in vasculitis

Two vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are recognized as autoimmune and autoinflammatory diseases that manifest exclusively within the aorta and its large branches. In both entities, the age of the affected host is a critical risk factor. TAK manifests during the 2nd-4th decade of life, occurring while the immune system is at its height of performance. GCA is a disease of older individuals, with infrequent cases during the 6th decade and peak incidence during the 8th decade of life. In both vasculitides, macrophages and T cells infiltrate into the adventitia and media of affected vessels, induce granulomatous inflammation, cause vessel wall destruction, and reprogram vascular cells to drive adventitial and neointimal expansion. In GCA, abnormal immunity originates in an aged immune system and evolves within the aged vascular microenvironment. One hallmark of the aging immune system is the preferential loss of CD8⁺ T cell function. Accordingly, in GCA but not in TAK, CD8⁺ effector T cells play a negligible role and anti-inflammatory CD8⁺ T regulatory cells are selectively impaired. Here, we review current evidence of how the process of immunosenescence impacts the risk for GCA and how fundamental differences in the age of the immune system translate into differences in the granulomatous immunopathology of TAK versus GCA.

Immune checkpoint molecule expression is altered in the skin and peripheral blood in vasculitis

Dysfunction of immunoinhibitory signals and persistent T cell activation reportedly play important roles in the development of vasculitis. The skin is one of the most accessible organs, and it is suitable for the characterization of immune cell signatures. However, the inhibitory checkpoint molecules in the skin and their relevance to vasculitis have not been studied. Here, we investigated the profile of immune checkpoint molecules in the skin and peripheral blood of patients with vasculitis and healthy donors. We found that some of the inhibitory checkpoint molecules, including programmed cell death 1 receptor (PD-1), were elevated in T-cells in the blood of patients with systemic and cutaneous vasculitis. In addition, programmed death-ligand 1 (PD-L1) expression was elevated in the skin of patients with cutaneous vasculitis. Histologically, PD-L1 was highly expressed in the vessels in the skin along with CD4⁺ and CD8⁺ T-cell infiltration in patients with cutaneous vasculitis. Notably, plasma soluble PD-L1 levels were increased, and these correlated with C-reactive protein in patients with systemic vasculitis. Our findings suggest that inhibitory checkpoint molecules might be differentially modulated in the skin and peripheral blood of patients with vasculitis, and that the alteration of the PD-L1/PD-1 axis may be associated with the regulation of T-cell activation in vasculitis.

The Germinal Center Milieu in Rheumatoid Arthritis: The Immunological Drummer or Dancer?

Rheumatoid Arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation, affecting approximately 1% of the general population. To alleviate symptoms and ameliorate joint damage, chronic use of immunosuppressives is needed. However, these treatments are only partially effective and may lead to unwanted side effects. Therefore, a more profound understanding of the pathophysiology might lead to more effective therapies, or better still, a cure. The presence of autoantibodies in RA indicates that B cells might have a pivotal role in the disease. This concept is further supported by the fact that a diverse antibody response to various arthritis-related epitopes is associated with arthritis development. In this context, attention has focused in recent years on the role of Germinal Centers (GCs) in RA. Since GCs act as the main anatomic location of somatic hypermutations, and, thus, contributing to the diversity and specificity of (auto) antibodies, it has been speculated that defects in germinal center reactions might be crucial in the initiation and maintenance of auto-immune events. In this paper, we discuss current evidence that various processes within GCs can result in the aberrant production of B cells that possess autoreactive properties and might result in the production of RA related autoantibodies. Secondly, we discuss various (pre-)clinical studies that have targeted various GC processes as novel therapies for RA treatment.

Cellular signaling pathways of T cells in giant cell arteritis

Giant cell arteritis (GCA) is a commonly occurring large vacuities characterized by angiopathy of medium and large-sized vessels. GCA granulomatous formation plays an important role in the pathogenesis of GCA. Analysis of T cell lineages and signaling pathways in GCA have revealed the essential role of T cells in the pathology of GCA. T cells are the dominant population present in GCA lesions. CD4+ T cell subtypes that are present include Th1, Th2, Th9, Th17, follicular helper T (Tfh) cells, and regulatory T (Treg) cells. CD8 T cells can primarily differentiate into cytotoxic CD8+ T lymphocytes and Treg cells. The instrumental part of GCA is the interplay between dendritic cells, macrophages and endothelial cells, which can result in the vascular injury and the characteristics granulomatous infiltrates formation. During the inflammatory loop of GCA, several signaling pathways have been reported to play an essential role in recruiting, activating and differentiating T cells, including T-cell receptor (TCR) signaling, vascular endothelial growth factor (VEGF)-Jagged-Notch signaling and the Janus kinase and signal transducer and activator of transcription (STAT) pathway (JAK-STAT) pathway. In this review, we have focused on the role of T cells and their potential signaling mechanism (s) that are involved in the pathogenesis of GCA. A better understanding of the role of T cells mediated complicated orchestration during the homeostasis and the changes could possibly favor developments of novel treatment strategies against immunological disorders associated with GCA.

Improvement of Treg immune response after treatment with tocilizumab in giant cell arteritis

Objectives

To study the percentage, suppressive function and plasticity of Treg in giant cell arteritis (GCA), and the effects of glucocorticoids and tocilizumab.

Methods

Blood samples were obtained from 40 controls and 43 GCA patients at baseline and after treatment with glucocorticoids + IV tocilizumab (n = 20) or glucocorticoids (n = 23). Treg percentage and phenotype were assessed by flow cytometry. Suppressive function of Treg was assessed by measuring their ability to inhibit effector T‐cell (Teff) proliferation and polarisation into Th1 and Th17 cells.

Results

Treg (CD4⁺CD25^highFoxP3⁺) frequency in total CD4⁺ T cells was decreased in active GCA patients when compared to controls (2.5% vs. 4.7%, P < 0.001) and increased after treatment with tocilizumab but worsened after treatment with glucocorticoids alone. Treg lacking exon 2 of FoxP3 were increased in GCA patients when compared to controls (23% vs. 10% of total Treg, P = 0.0096) and normalised after treatment with tocilizumab + glucocorticoids but not glucocorticoids alone. In GCA patients, Treg were unable to control Teff proliferation and induced ˜50% increase in the amount of IL‐17⁺ Teff, which was improved after in vitro blockade of the IL‐6 pathway by tocilizumab.

Conclusion

This study reports quantitative and functional disruptions in the regulatory immune response of GCA patients and demonstrates that, unlike glucocorticoids, tocilizumab improves Treg immune response.

Efficacy and safety of secukinumab in patients with giant cell arteritis: study protocol for a randomized, parallel group, double-blind, placebo-controlled phase II trial

Background

One key pathological finding in giant cell arteritis (GCA) is the presence of interferon-gamma and interleukin (IL)-17 producing T helper (Th) 1 and Th17 cells in affected arteries. There is anecdotal evidence of successful induction and maintenance of remission with the monoclonal anti-IL-17A antibody secukinumab. Inhibition of IL-17A could therefore represent a potential new therapeutic option for the treatment of GCA.

Methods

This is a randomized, parallel-group, double-blind, placebo-controlled, multi-center, phase II study in which patients, treating physicians, and the associated clinical staff as well as the sponsor clinical team are blinded. It is designed to evaluate efficacy and safety of secukinumab compared to placebo in combination with an open-label prednisolone taper regimen. Patients included are naïve to biological therapy and have newly diagnosed or relapsing GCA. Fifty patients are randomly assigned in a 1:1 ratio to receive either 300 mg secukinumab or placebo subcutaneously at baseline, weeks 1, 2 and 3, and every 4 weeks from week 4. Patients in both treatment arms receive a 26-week prednisolone taper regimen. The study consists of a maximum 6-week screening period, a 52-week treatment period (including the 26-week tapering), and an 8-week safety follow-up, with primary and secondary endpoint assessments at week 28. Patients who do not achieve remission by week 12 experience a flare after remission or cannot adhere to the prednisolone tapering will enter the escape arm and receive prednisolone at a dose determined by the investigator’s clinical judgment. The blinded treatment is continued. Two optional imaging sub-studies are included (ultrasound and contrast-media enhanced magnetic resonance angiography [MRA]) to assess vessel wall inflammation and occlusion before and after treatment. The primary endpoint is the proportion of patients in sustained remission until week 28 in the secukinumab group compared to the proportion of patients in the placebo group. A Bayesian approach is applied.

Discussion

The trial design allows the first placebo-controlled data collection on the efficacy and safety of secukinumab in patients with GCA.

Trial registration

ClinicalTrials.gov NCT03765788. Registration on 5 December 2018, prospective registration, EudraCT number 2018-002610-12; clinical trial protocol number CAIN457ADE11C.

An update on the pathogenic role of IL-6 in rheumatic diseases

Interleukin (IL)-6 is a pleiotropic cytokine that is involved in the pathogenesis of various rheumatic diseases. Direct inhibition of the IL-6 pathway by an anti-IL-6 receptor or inhibiting the ligand itself has proved to be efficacious in the treatment of these diseases. Juvenile idiopathic arthritis, adult-onset Still's disease, large vessel vasculitis including giant cell arteritis and Takayasu disease, systemic sclerosis, and polymyalgia rheumatica respond well to IL-6 inhibition as expected. However, no clinically meaningful effect has been observed with regard to IL-6 blockade in ankylosing spondylitis, psoriatic arthritis, and systemic lupus erythematosus. This review discusses the current state of IL-6 targeting approaches in various rheumatic diseases other than rheumatoid arthritis.

Tocilizumab monotherapy uncovered the role of the CCL22/17-CCR4+ Treg axis during remission of crescentic glomerulonephritis

Objectives

Tocilizumab (TCZ) is a humanised anti‐interleukin (IL)‐6 receptor (IL‐6R) monoclonal antibody that is a promising agent to treat various autoimmune diseases. However, the mechanism of TCZ efficacy is unclear. This study aims to elucidate the relationship between Tregs and IL‐6R blockade in autoimmunity‐mediated renal disease based on a TCZ‐treated cohort of patients with anti‐neutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV) and in an experimental model of crescentic glomerulonephritis (cGN).

Methods

We examined multiple serum levels of cytokines and chemokines and peripheral blood mononuclear cells in patients with AAV who received TCZ monotherapy and achieved drug‐free remission. Moreover, we investigated the mechanistic role of IL‐6R blockade in accelerated cGN model to analyse the local sites of inflammation.

Results

Serum chemokines CCL22 and CCL17, in addition to the CCR4⁺Foxp3⁺ Treg population, increased in patients who demonstrated drug‐free remission after the cessation of TCZ. In the cGN model, IL‐6R blockade ameliorated the disease, elevated CCL22/17 in CD206⁺CD11b⁺CD11c⁺ kidney M2‐like type macrophages, and increased the migration of Tregs into the kidney and regional lymph nodes. The local administration of CCL22 in the kidney facilitated Treg accumulation and reduced glomerular crescent formation.

Conclusions

This study revealed a new mechanism whereby effector Tregs migrate into the inflammatory kidney via the CCL22/17–CCR4 axis that is facilitated by M2‐like type macrophages that are induced by IL‐6R blockade.

T Cells in Autoimmunity-Associated Cardiovascular Diseases

T cells are indisputably critical mediators of atherosclerotic cardiovascular disease (CVD), where they secrete pro-inflammatory cytokines that promote vascular pathology. Equally well-established is the fact that autoimmune diseases, which are mediated by autoreactive T cells, substantially increase the risk of developing CVD. Indeed, as immunomodulatory treatments have become more effective at treating end-organ pathology, CVD has become a leading cause of death in patients with autoimmune diseases. Despite this, investigators have only recently begun to probe the mechanisms by which autoreactive T cells promote CVD in the context of autoimmune diseases. T cells are best-studied in the pathogenesis of systemic vasculitides, where they react to self-antigen in the vessel wall. However, newer studies indicate that T cells also contribute to the increased CVD risk associated with lupus and rheumatoid arthritis. Given the central role of T-cell-derived cytokines in the pathogenesis of psoriasis, the role of these factors in psoriatic CVD is also under investigation. In the future, T cells are likely to represent major targets for the prevention and treatment of CVD in patients with autoimmune diseases.

Cellular Signaling Pathways in Medium and Large Vessel Vasculitis

Autoimmune and autoinflammatory diseases of the medium and large arteries, including the aorta, cause life-threatening complications due to vessel wall destruction but also by wall remodeling, such as the formation of wall-penetrating microvessels and lumen-stenosing neointima. The two most frequent large vessel vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are HLA-associated diseases, strongly suggestive for a critical role of T cells and antigen recognition in disease pathogenesis. Recent studies have revealed a growing spectrum of effector functions through which T cells participate in the immunopathology of GCA and TAK; causing the disease-specific patterning of pathology and clinical outcome. Core pathogenic features of disease-relevant T cells rely on the interaction with endothelial cells, dendritic cells and macrophages and lead to vessel wall invasion, formation of tissue-damaging granulomatous infiltrates and induction of the name-giving multinucleated giant cells. Besides antigen, pathogenic T cells encounter danger signals in their immediate microenvironment that they translate into disease-relevant effector functions. Decisive signaling pathways, such as the AKT pathway, the NOTCH pathway, and the JAK/STAT pathway modify antigen-induced T cell activation and emerge as promising therapeutic targets to halt disease progression and, eventually, reset the immune system to reestablish the immune privilege of the arterial wall.

hsa_circ_0003738 Inhibits the Suppressive Function of Tregs by Targeting miR-562/IL-17A and miR-490-5p/IFN-γ Signaling Pathway

Dysfunction in the suppressive function of regulatory T cells (Tregs) has been related to the pathogenesis of psoriasis. Accumulating evidence has demonstrated the importance of circular RNAs (circRNAs) in regulating various biological process, such as cell proliferation, apoptosis, etc. However, the role of circRNAs in modulating the suppressive functions of psoriatic Tregs and the underlying mechanisms have not been investigated. Here, by using circRNA microarray analysis, we discovered four upregulated and four downregulated circRNAs in psoriatic Tregs. Quantitative real-time PCR further confirmed a significant increase of circ_0003738 in psoriatic Tregs. Importantly, knockdown of circ_0003738 by lentivirus in psoriatic Tregs could restore their suppressive functions via inhibiting the secretion of proinflammatory cytokines interleukin-17A (IL-17A) and interferon (IFN)-γ. Moreover, we found that circ_0003738 could bind to miR-562 to release the inhibition of target gene IL-17RA (IL-17 receptor A), thus promoting IL-17A signaling in psoriatic Tregs. In parallel, circ_0003738 acted also as a sponge for miR-490-5p and relieved inhibition for the target gene IFNGR2, which promoted IFN-γ signaling in psoriatic Tregs. Our study demonstrated that upregulated circ_0003738 decreased the suppressive function of psoriatic Tregs via the miR-562/IL17RA and miR-490-5p/IFNGR2 (IFN-γ receptor 2) axis, which indicated the involvement of circRNAs in the pathogenesis of dysfunctional Tregs. These findings will provide new therapeutic targets for the treatment of psoriasis.

A Multicentre, Randomised, Double-Blind, Placebo-Controlled, Parallel-Group Study to Evaluate the Efficacy and Safety of Sirukumab in the Treatment of Giant Cell Arteritis

INTRODUCTION

To evaluate the efficacy and safety of sirukumab in giant cell arteritis (GCA).

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, two-part phase 3 trial (NCT02531633; Part A [52-week double-blind treatment]; Part B [104-week follow-up]), patients with GCA were randomised (3:3:2:2:2) to sirukumab 100 mg every 2 weeks plus 6-month or 3-month prednisone taper, sirukumab 50 mg every 4 weeks plus 6-month prednisone taper, or placebo every 2 weeks plus 6-month or 12-month prednisone taper. The primary endpoint was the proportion of patients in sustained remission at week 52. Secondary endpoints included disease flare and safety. The study was terminated early (October 2017; sponsor decision).

RESULTS

Of 161 patients randomised (sirukumab: n = 107; placebo: n = 54), 28 (17.4%) completed week 52 (median treatment duration: 24-30 weeks). In a revised intent-to-treat (ITT) subgroup (completed week 52 or discontinued before study termination [n = 55]); six patients (all receiving sirukumab) achieved the primary endpoint. In the ITT population (n = 161), the proportion of patients with flares (week 2-52) was lower with sirukumab (18.4-30.8%) than placebo (37.0-40.0%). The proportion of patients with flares (week 2-12) was highest with sirukumab 100 mg every 2 weeks plus 3-month prednisone taper (23.1%). In Part A, 94.4% of patients reported ≥ 1 treatment-emergent adverse event (TEAE); 19.3% reported serious TEAEs. The proportions of patients with TEAEs were generally similar across treatment arms. No deaths occurred.

CONCLUSIONS

Although data were limited due to early termination and shortened treatment duration, sirukumab treatment resulted in numerically lower proportions of patients with flare by week 52 versus placebo, with no unexpected safety findings.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02531633.

Dawn of Monitoring Regulatory T Cells in (Pre-)clinical Studies: Their Relevance Is Slowly Recognised

Regulatory T cells (Tregs) have a prominent role in the control of immune homeostasis. Pharmacological impact on their activity or balance with effector T cells could contribute to (impaired) clinical responses or adverse events. Monitoring treatment-related effects on T cell subsets may therefore be part of (pre-)clinical studies for medicinal products. However, the extent of immune monitoring performed in studies for marketing authorisation and the degree of correspondence with data available in the public domain is not known. We evaluated the presence of T cell immunomonitoring in 46 registration dossiers of monoclonal antibodies indicated for immune-related disorders and published scientific papers. We found that the depth of Treg analysis in registration dossiers was rather small. Nevertheless, data on treatment-related Treg effects are available in public academia-driven studies (post-registration) and suggest that Tregs may act as a biomarker for clinical responses. However, public data are fragmented and obtained with heterogeneity of experimental approaches from a diversity of species and tissues. To reveal the potential added value of T cell (and particular Treg) evaluation in (pre-)clinical studies, more cell-specific data should be acquired, at least for medicinal products with an immunomodulatory mechanism. Therefore, extensive analysis of T cell subset contribution to clinical responses and the relevance of treatment-induced changes in their levels is needed. Preferably, industry and academia should work together to obtain these data in a standardised manner and to enrich our knowledge about T cell activity in disease pathogenesis and therapies. This will ultimately elucidate the necessity of T cell subset monitoring in the therapeutic benefit-risk assessment.

Significant association between clinical characteristics and changes in peripheral immuno-phenotype in large vessel vasculitis

Background

Large vessel vasculitis (LVV) is a type of vasculitis characterized by granulomatous inflammation of medium- and large-sized arteries. Clinical assessment of acute phase reactants has been conventionally used to diagnose and monitor diseases; however, accurate assessment of vascular disease activity status can be difficult. In this study, we investigated comprehensive immuno-phenotyping to explore useful biomarkers associated with clinical characteristics.

Methods

Consecutive patients with newly diagnosed LVV who visited our institution between May 2016 and May 2019 were enrolled. The number of circulating T cells, B cells, natural killer cells, dendritic cells, monocytes, and granulocytes was examined and chronologically followed. Baseline and time-course changes in immuno-phenotyping associated with disease activity were assessed.

Results

Comprehensive immuno-phenotyping data from 90 samples from each of 20 patients with LVV were compared with those from healthy controls (HCs). The number of helper T (Th), follicular helper T (Tfh), CD8⁺ T, CD14⁺⁺ CD16⁺ monocytes, and neutrophils were higher in patients with giant cell arteritis (GCA) and/or Takayasu arteritis (TAK) than in HCs. Among them, the number of CD8⁺ T and CD8⁺ Tem were higher in patients with TAK than in GCA. Notably, memory CD4⁺ and CD8⁺ T cells in patients with TAK remained high even in the remission phase. Further analysis revealed that the number of Th1, Th17, and Tfh cells was associated with disease relapse in GCA and TAK and that the number of CD8⁺ T cells was associated with relapse in TAK. Th1, Th17, and Tfh cells decreased after treatment with biologic agents, while CD8⁺ T cells did not.

Conclusions

Our results from peripheral immuno-phenotyping analysis indicate that the numbers of Th and Tfh cells changed along with the disease condition in both GCA and TAK, while that of CD8⁺ T cells did not, especially in TAK. Treatment with biologic agents decreased the proportion of Th and Tfh cells, but not CD8⁺ T cells, in the patients. Chronological immuno-phenotyping data explained the difference in therapeutic response, such as reactivities against biologics, between GCA and TAK.

[Physiopathology of giant cell arteritis: From inflammation to vascular remodeling]

Giant cell arteritis (GCA) is a large-vessel vasculitis involving the aorta and its main branches, especially supra aortic branches. Although much progress has been made, the pathophysiology remains incompletely understood. An initial trigger, suspected of infectious origin, lead to the maturation and recruitment of dendritic cells (DC). The lack of migration of these DC allows the local recruitment of T-lymphocytes (LT). These LT- CD4⁺ polarize in Type 1 helper (Th1), Th17 but also Th9. A qualitative and quantitative deficit in regulatory T cells (Treg) is observed under the influence of IL-21 overproduction. In addition, an imbalance in the Th17/Treg balance is favored by IL-6. The secretion of IFN-γ, IL-17, IL-6, IL-33 is responsible for a sustained local inflammatory reaction that is organized around tertiary lymphoid follicles. Locally recruited macrophages secrete reactive forms of oxygen together with VEGF and PDGF. These growth factors, together with neurotrophins and endothelin contribute to increase the proliferation of vascular smooth muscle cells (VSMCs). The imbalance between matrix metalloproteases (MMP)-2, MMP-9 and MMP-14 and tissue inhibitors of metalloproteases (TIMP)-1 and TIMP-2 also contribute to the remodeling process occurring in the vessel wall. Finally, arterial neovascularization contribute to the perpetuation of lymphocyte recruitment. This persistent remodeling is sometimes complicated by ischemic events responsible for the initial severity of the disease.

Increased miR-142-3p Expression Might Explain Reduced Regulatory T Cell Function in Granulomatosis With Polyangiitis

Objectives: Regulatory T cells (Tregs) are frequently functionally impaired in patients with granulomatosis with polyangiitis (GPA). However, the mechanism underlying their impaired function is unknown. Here, we hypothesized that Treg dysfunction in GPA is due to altered microRNA (miRNA) expression. Methods: RNA isolated from FACS-sorted memory (_M) Tregs (CD4⁺CD45RO⁺CD25⁺CD127^-) of 8 healthy controls (HCs) and 8 GPA patients without treatment was subjected to miRNA microarray analysis. Five differentially expressed miRNAs were validated in a larger cohort by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). An miRNA target gene database search revealed targets that were tested with RT-qPCR in _MTregs from patients and HCs. cAMP levels were measured using flow cytometry. Results: Microarray analysis revealed 19 differentially expressed miRNAs, of which miR-142-3p was confirmed to be significantly upregulated in _MTregs from GPA patients compared to those from HCs (1.9-fold, p = 0.03). In vitro overexpression of miR-142-3p lowered the suppressive capacity of _MTregs (2.1-fold, p = 0.03), and miR-142-3p expression correlated negatively with the suppressive capacity (rho = -0.446, p = 0.04). Overexpression of miR-142-3p significantly decreased cAMP levels (p = 0.02) and tended to decrease the mRNA levels of a predicted target gene, adenylate cyclase 9 (ADCY9; p = 0.06). In comparison to those from HCs, _MTregs from GPA patients had lower ADCY9 mRNA levels (2-fold, p = 0.008) and produced significantly less cAMP after stimulation. Importantly, induction of cAMP production in miR-142-3p overexpressed _MTregs by forskolin restored their suppressive function in vitro. Conclusion: Overexpression of miR-142-3p in _MTregs from GPA patients might cause functional impairment by targeting ADCY9, which leads to the suppression of cAMP production.