Causal relationship between immune cells and the risk of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis: A Mendelian randomization study.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare inflammatory disease categorized as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. The majority of patients are ANCA-positive, predominantly against myeloperoxidase (MPO). Previous studies have predominantly concentrated on the association between EGPA and neutrophils, but recent research has emphasized the role of lymphocytes in the development of EGPA. The objective of our research was to examine the causal association between immune cells and MPO + ANCA EGPA. A two-sample bidirectional Mendelian randomization (MR) analysis was performed, which included 159 MPO + ANCA EGPA cases and 6688 controls and utilized Genome-Wind Associaton Studies (GWAS) summary statistics of immune traits from approximately 3757 individuals, encompassing around 22 million single nucleotide polymorphisms (SNPs). Our findings revealed that 23 immunophenotypes were associated with MPO + ANCA EGPA. Furthermore, the reverse MR analysis showed that MPO + ANCA EGPA had significant causal effects on three immunophenotypes within the Treg panel. By integrating existing research, our study unveiled the contributions of Tregs, B cells, and monocytes to the development of EGPA. Subgroup analysis specifically examined the roles of lymphocyte subtypes, cytokines, and their surface molecules in the pathogenic mechanisms of the disease. This comprehensive approach provides a novel perspective on the biological mechanisms and early intervention strategies for MPO + ANCA EGPA by focusing on immune cells.

Constitutive and induced forms of membrane-bound proteinase 3 interact with antineutrophil cytoplasmic antibodies and promote immune activation of neutrophils.

Proteinase 3 (PR3) is the main target antigen of antineutrophil cytoplasmic antibodies (ANCAs) in PR3-ANCA-associated vasculitis. A small fraction of PR3 is constitutively exposed on the surface of quiescent blood neutrophils in a proteolytically inactive form. When activated, neutrophils expose an induced form of membrane-bound PR3 (PR3mb) on their surface as well, which is enzymatically less active than unbound PR3 in solution due to its altered conformation. In this work, our objective was to understand the respective role of constitutive and induced PR3mb in the immune activation of neutrophils triggered by murine anti-PR3 mAbs and human PR3-ANCA. We quantified immune activation of neutrophils by the measurement of the production of superoxide anions and secreted protease activity in the cell supernatant before and after treatment of the cells by alpha-1 protease inhibitor that clears induced PR3mb from the cell surface. Incubation of TNFα-primed neutrophils with anti-PR3 antibodies resulted in a significant increase in superoxide anion production, membrane activation marker exposition, and secreted protease activity. When primed neutrophils were first treated with alpha-1 protease inhibitor, we observed a partial reduction in antibody-induced neutrophil activation, suggesting that constitutive PR3mb is sufficient to activate neutrophils. The pretreatment of primed neutrophils with purified antigen-binding fragments used as competitor significantly reduced cell activation by whole antibodies. This led us to the conclusion that PR3mb promoted immune activation of neutrophils. We propose that blocking and/or elimination of PR3mb offers a new therapeutic strategy to attenuate neutrophil activation in patients with PR3-ANCA-associated vasculitis.

Genetic and Non-Genetic Contributions to Eosinophilic Granulomatosis with Polyangiitis: Current Knowledge and Future Perspectives.

In this work, we present a comprehensive overview of the genetic and non-genetic complexity of eosinophilic granulomatosis with polyangiitis (EGPA). EGPA is a rare complex systemic disease that occurs in people presenting with severe asthma and high eosinophilia. After briefly introducing EGPA and its relationship with the anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAVs), we delve into the complexity of this disease. At first, the two main biological actors, ANCA and eosinophils, are presented. Biological and clinical phenotypes related to ANCA positivity or negativity are explained, as well as the role of eosinophils and their pathological subtypes, pointing out their intricate relations with EGPA. Then, the genetics of EGPA are described, providing an overview of the research effort to unravel them. Candidate gene studies have investigated biologically relevant candidate genes; the more recent genome-wide association studies and meta-analyses, able to analyze the whole genome, have confirmed previous associations and discovered novel risk loci; in the end, family-based studies have dissected the contribution of rare variants and the heritability of EGPA. Then, we briefly present the environmental contribution to EGPA, reporting seasonal events and pollutants as triggering factors. In the end, the latest omic research is discussed and the most recent epigenomic, transcriptomic and microbiome studies are presented, highlighting the current challenges, open questions and suggesting approaches to unraveling this complex disease.

Myeloperoxidase-ANCA IgG induces different forms of small vessel vasculitis based on type of synergistic immune stimuli.

Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis has diverse patterns of injury including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Necrotizing and crescentic glomerulonephritis (NCGN) occurs in all syndromes and as renal limited vasculitis (RLV). Single-dose intravenous ANCA IgG-specific for mouse myeloperoxidase (MPO) causes RLV in mice. Although multiple mouse models have elucidated ANCA-IgG induced necrotizing and crescentic glomerulonephritis (NCGN), pathogenesis of ANCA-induced granulomatosis and vasculitis outside the kidney has not been clarified. To investigate this, we used intravenous MPO-ANCA IgG in the same strain of mice to induce different patterns of lung disease mirroring patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Repeated intravenous MPO-ANCA IgG induced GPA with NCGN, lung capillaritis, arteritis and granulomatosis. Lung leukocyte phenotypes were evaluated by immunohistochemical image analysis and by flow cytometry. ANCA lung capillaritis and microabscesses began within one day and evolved into granulomas in under seven days. Influenza plus single-dose MPO-ANCA IgG induced MPA with NCGN, lung capillaritis and arteritis, but no granulomatosis. Allergic airway disease caused by house dust mites or ovalbumin plus single-dose intravenous MPO-ANCA IgG induced EGPA with eosinophilic bronchiolitis, NCGN, capillaritis, arteritis, and granulomatosis. Thus, our study shows that the occurrence and pattern of lung lesions are determined by the same ANCA IgG accompanied by different synergistic immune factors.

Complement alternative pathway determines disease susceptibility and severity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis.

Activation of the alternative pathway (AP) of complement is involved in the pathogenesis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), although the underlying molecular mechanisms are unclear. To gain insight into the role of the AP, common gene variants in CFH/CFHR1-5, CFB, C3 and MCP, and longitudinal determinations of plasma C3, C4, FH, FHR-1, FHR-2, FHR-5, FB, properdin and sC5b-9 levels were analyzed in a Spanish AAV cohort consisting of 102 patients; 54 with active AAV (active cohort) and 48 in remission not receiving immunosuppressants or dialysis therapy (remission cohort). The validation cohort consisted of 100 patients with ANCA-associated glomerulonephritis. Here, we demonstrated that common genetic variants in complement components of the AP are associated with disease susceptibility (CFB32Q/W) or severity of kidney damage in AAV (CFH-H1, CFH1H2 and ΔCFHR3/1). Plasma levels of complement components were significantly different between active and remission cohorts. In longitudinal observations, a high degree of AP activation at diagnosis was associated with worse disease outcome, while high basal FHR-1 levels and lower FH/FHR-1 ratios determined severe forms of kidney associated AAV. These genetic and plasmatic findings were confirmed in the validation cohort. Additionally, autoantibodies against FH and C3 convertase were identified in one and five active patients, respectively. Thus, our study identified key genetic and plasma components of the AP that determine disease susceptibility, prognosis, and severity in AAV. Our data also suggests that balance between FH and FHR-1 is critical and supports FHR-1 as a novel AP-specific therapeutic target in AAV.

Executive summary of the KDIGO 2024 Clinical Practice Guideline for the Management of ANCA-Associated Vasculitis.

In 2021, the Kidney Disease: Improving Global Outcomes (KDIGO) Guideline for the Management of Glomerular Diseases was published. KDIGO is committed to providing the nephrology community with periodic updates, based on new developments for each disease. For patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), avacopan received regulatory approval in late 2021, leading to this KDIGO guideline update. In addition, the evidence supporting a lower-dose glucocorticoid induction regimen or even complete replacement of glucocorticoids has become stronger. Herein, an executive summary of the most important guideline changes from the AAV chapter is provided as a quick reference.

Significance of clinical-immunological patterns and diagnostic yield of biopsies in microscopic polyangiitis and granulomatosis with polyangiitis.

BACKGROUND: Microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) are the two major antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). OBJECTIVES: To characterize a homogenous AAV cohort and to assess the impact of clinicopathological profiles and ANCA serotypes on clinical presentation and prognosis. Clinical differences in GPA patients according to ANCA serotype and the diagnostic yield for vasculitis of biopsies in different territories were also investigated. RESULTS: This retrospective study (2000-2021) included 152 patients with AAV (77 MPA/75 GPA). MPA patients (96.1% myeloperoxidase [MPO]-ANCA and 2.6% proteinase 3 [PR3]-ANCA) presented more often with weight loss, myalgia, renal involvement, interstitial lung disease (ILD), cutaneous purpura, and peripheral nerve involvement. Patients with GPA (44% PR3-ANCA, 33.3% MPO, and 22.7% negative/atypical ANCA) presented more commonly with ear, nose, and throat and eye/orbital manifestations, more relapses, and higher survival than patients with MPA. GPA was the only independent risk factor for relapse. Poor survival predictors were older age at diagnosis and peripheral nerve involvement. ANCA serotypes differentiated clinical features in a lesser degree than clinical phenotypes. A mean of 1.5 biopsies were performed in 93.4% of patients in different territories. Overall, vasculitis was identified in 80.3% (97.3% in MPA and 61.8% in GPA) of patients. CONCLUSIONS: The identification of GPA presentations associated with MPO-ANCA and awareness of risk factors for relapse and mortality are important to guide proper therapeutic strategies in AAV patients. Biopsies of different affected territories should be pursued in difficult-to-diagnose patients based on their significant diagnostic yield.

An update on risk factors for relapse in antineutrophil cytoplasmic antibody-associated vasculitis.

Ongoing therapeutic advances in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) have significantly reduced the risk of death in AAV, but 30%-50% of patients still relapse. Relapse is a major problem in these diseases, leading to increased morbidity and mortality. It is, therefore, necessary to find predictors of relapse at the end of the remission induction and maintenance phases in order to personalize treatment.

Circulating B Cells Display Differential Immune Regulatory Molecule Expression in Granulomatosis with Polyangiitis.

Granulomatosis with polyangiitis (GPA) is a B cell-mediated, relapsing, autoimmune disease. There is a need for novel therapeutic approaches and relapse markers to achieve durable remission. B cells express immune regulatory molecules that modulate their activation and maintain tolerance. While recent studies show dysregulation of these molecules in other autoimmune diseases, data on their expression in GPA are limited. This study aimed to map the expression of surface immune regulatory molecules on circulating B cell subsets in GPA and correlate their expression with clinical parameters. Immune regulatory molecule expression on circulating B cell subsets was comprehensively examined in active GPA (n=16), GPA in remission (n=16), and healthy controls (HCs, n=16) cross-sectionally using a 35-color B cell-specific spectral flow cytometry panel. Our supervised and unsupervised in-depth analysis revealed differential expression of inhibitory and stimulatory immune molecules on distinct B cell populations in GPA, with the most notable differences observed in active GPA. These differences include the upregulation of FcγRIIB on non-mature B cells, downregulation of CD21 and upregulation of CD86 on antigen-experienced B cells, and elevated CD22 expression on various populations. Additionally, we found a strong association between FcγRIIB, BTLA, and CD21 expression on specific B cell populations and disease activity in GPA. Together, these findings provide novel insights into the immune regulatory molecule expression profile of B cells in GPA, and could potentially form the foundation for new therapeutic approaches and disease monitoring markers.

Risk factors for hypogammaglobulinemia and association with relapse and severe infections in ANCA-associated vasculitis: A cohort study.

OBJECTIVES: B-cell depletion induced by rituximab (RTX) in ANCA-associated vasculitis (AAV) is a risk factor for hypogammaglobulinemia. Aggregating data on gammaglobulin levels kinetics during RTX and its association with the risk of relapse and severe infection is of interest. METHODS: Gammaglobulin levels were collected before induction therapy and during RTX maintenance therapy. We used different definitions of gammaglobulin decline: 1/gammaglobulin levels <6 g/L after induction; 2/>25 % decline in gammaglobulin levels between induction and maintenance, and 3/both. Our primary objective was the impact of gammaglobulin decline on the risk of relapse and severe infections. RESULTS: We included 98 patients. Patients with gammaglobulin level <6 g/L after induction and gammaglobulin decline >25 % were older (OR 3.9; 95%CI 1.1-16.1), had more frequently baseline gammaglobulin levels <10 g/L (OR 6.0; 95%CI 1.7-25.8) and received more frequent pulses of methylprednisolone at induction (OR 4.6; 95%CI 1.3-18.5). Severe infection-free survival was significantly poorer in patients with both gammaglobulin <6 g/L and gammaglobulin decline >25 % (adjusted HR 2.3; 95%CI 1.0-5.1) and in those who received pulses of methylprednisolone (HR 5.6; 95%CI 2.3-13.4). Gammaglobulin decline was in contrast not associated with the risk of relapse. CONCLUSION: Older age, low gammaglobulin levels and pulses of methylprednisolone at induction increase the likelihood of gammaglobulin decline after induction therapy. Such decline was associated with an increased risk of severe infections but not lower risk of vasculitis relapse. Pulses of methylprednisolone at induction had an independent negative impact on gammaglobulin levels and the risk of severe infections.

Balancing efficacy and safety of complement inhibitors.

Complement inhibitors have been approved for several immune-mediated diseases and they are considered the next paradigm-shifting approach in the treatment of glomerulonephritis. The hierarchical organization of the complement system offers numerous molecular targets for therapeutic intervention. However, complement is an integral element of host defense and therefore complement inhibition can be associated with serious infectious complications. Here we give a closer look to the hierarchical complement system and how interfering with proximal versus distal or selective versus unselective molecular targets could determine efficacy and safety. Furthermore, we propose to consider the type of disease, immunological activity, and patient immunocompetence when stratifying patients, e.g., proximal/unselective targets for highly active and potentially fatal diseases while distal and selective targets may suit more chronic disease conditions with low or moderate disease activity requiring persistent complement blockade in patients with concomitant immunodeficiency. Certainly, there exists substantial promise for anti-complement therapeutics. However, balancing efficacy and safety will be key to establish powerful treatment effects with minimal adverse events, especially when complement blockade is continued over longer periods of time in chronic disorders.

Regulatory T cells effectively downregulate the autoimmune anti-MPO response and ameliorate anti-MPO induced glomerulonephritis in mice.

Regulation of autoreactive cells is key for both prevention and amelioration of autoimmune disease. A better understanding of the key cell population(s) responsible for downregulation of autoreactive cells would provide necessary foundational insight for cellular-based therapies in autoimmune disease. Utilizing a mouse model of anti-myeloperoxidase (MPO) glomerulonephritis, we sought to understand which immune cells contribute to downregulation of the anti-MPO autoimmune response. MPO-/- mice were immunized with whole MPO to induce an anti-MPO response. Anti-MPO splenocytes were then transferred into recipient mice (Rag2-/- mice or WT mice). Anti-MPO titers were followed over time. After anti-MPO splenocyte transfer, WT mice are able to downregulate the anti-MPO response while anti-MPO titers persist in Rag2-/- recipients. Reconstitution with WT splenocytes into Rag2-/- recipients prior to anti-MPO splenocyte transfer enabled mice to downregulate the anti-MPO immune response. Therefore, wildtype splenocytes contain a cellular population that is capable of downregulating the autoimmune response. Through splenocyte transfer, antibody depletion experiments, and purified cell population transfers, we confirmed that the regulatory T cell (Treg) population is responsible for the downregulation of the anti-MPO autoimmune response. Further investigation revealed that functional Tregs from WT mice are capable of downregulating anti-MPO antibody production and ameliorate anti-MPO induced glomerulonephritis. These data underscore the importance of functional Tregs for control of autoimmune responses and prevention of end-organ damage due to autoimmunity.

Circulating immune profile in granulomatosis with polyangiitis reveals distinct patterns related to disease activity.

Granulomatosis with polyangiitis (GPA) is an autoimmune disorder characterized by recurrent relapses that can cause severe tissue damage and life-threatening organ dysfunction. Multiple immune cells and cytokines/chemokines are involved in the different stages of the disease. Immune profiling of patients may be useful for tracking disease activity, however, reliable immune signatures for GPA activity are lacking. In this study, we examined circulating immune profiles in GPA patients during active and remission disease states to identify potential immune patterns associated with disease activity. The distribution and phenotypic characteristics of major circulating immune cells, and the profiles of circulating cytokines/chemokines, were studied on cryopreserved peripheral blood mononuclear cells from GPA patients (active, n = 20; remission, n = 20) and healthy controls (n = 20) leveraging a 40-color optimized multicolor immunofluorescence panel (OMIP-69) and in serum using a 46-plex Luminex multiplex assay, respectively. Deep phenotyping uncovered a distinct composition of major circulating immune cells in active GPA and GPA in remission, with the most significant findings emerging within the monocyte compartment. Our detailed analysis revealed circulating monocyte diversity beyond the conventional monocyte subsets. We identified eight classical monocyte populations, two intermediate monocyte populations, and one non-classical monocyte population. Notably, active GPA had a higher frequency of CD45RA+CCR5+CCR6-CCR7+/lowCD127-HLA-DR+CD2- classical monocytes and a lower frequency of CD45RA-CCR5-/lowCCR6-CCR7-CD127-HLA-DR+CD2+/- classical monocytes, which both strongly correlated with disease activity. Furthermore, serum levels of CXCL1, CXCL2, and CCL20, all linked to monocyte biology, were elevated in active GPA and correlated strongly with disease activity. These findings shed light on the circulating immune profile of GPA and may lead to immune signature profiles for assessing disease activity. Monocytes in particular may be studied further as potential markers for monitoring GPA.

Lupus Nephritis Patterns and Response to Type I Interferon in Patients With DNASE1L3 Variants: Report of Three Cases.

DNASE1L3 is an extracellular nuclease that digests chromatin released from apoptotic cells. DNASE1L3 variants impair the enzyme function, enhance autoantibody production and type I interferon (IFN-I) responses, and cause different autosomal recessive phenotypes ranging from hypocomplementemic urticarial vasculitis syndrome to full-blown systemic lupus erythematosus (SLE). Kidney involvement in patients with DNASE1L3 variants is poorly characterized. Herein, we describe the clinical course of 3 children with monogenic SLE due to DNASE1L3 variants who developed refractory glomerulonephritis leading to kidney failure. They had different renal histopathological patterns (ie, membranous, endocapillary, and extracapillary glomerulonephritis and thrombotic microangiopathy), all belonging to the lupus nephritis (LN) spectrum. One patient had a mixed phenotype, showing an overlap between SLE and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Using immunofluorescence, we detected glomerular expression of the IFN-I-induced human myxovirus resistance protein 1 (MXA), which was particularly evident in glomerular endothelial cells. Two of the patients had increased expression of interferon-stimulated genes in the peripheral blood, and all 3 patients had reduced serum DNAse activity. Our findings suggest that DNASE1L3-related glomerulonephritis can be included in the spectrum of IFN-I-mediated kidney disorders and provide the rationale for IFN-I-directed therapies in order to improve the poor outcome of this rare condition.

Performance of clinical and histological prognostic scores for kidney survival in ANCA-associated vasculitis.

OBJECTIVES: Integrating clinical and histological parameters into prognostic scores may enhance the prediction of progression to kidney failure in anti-neutrophil cytoplasm antibodies-associated vasculitis (AAV). This study aimed to evaluate the prognostic performance of histological classifications and scoring systems for kidney survival in AAV. METHODS: This retrospective cohort study included 101 AAV patients with kidney involvement diagnosed by biopsy and followed for ≥12 months. The main outcome was the time to kidney failure. The prognostic performance of each histological and prognostic score was evaluated using Harrell's C statistic and Akaike's Information Criteria. RESULTS: Among the 101 patients, 37 progressed to kidney failure over a median follow-up of 75 months (IQR 39-123). The Harrell's C statistic was 0.702 (0.620-0.784), 0.606 (0.473-0.738), 0.801 (0.736-0.867), 0.782 (0.706-0.858), and 0.817 (0.749-0.885) for the EUVAS/Berden classification, Mayo Clinic Chronicity Score, Percentage of ANCA Crescentic Score (PACS), ANCA renal risk score (ARRS), and the improved ANCA kidney risk score (AKRiS), respectively. The AKRiS best discriminated the risk of kidney failure progression among subgroups. The AKRiS performance decreased with longer follow-up intervals. Adding the peak estimated glomerular filtration rate attained post-therapy improved the AKRiS performance at all follow-up intervals. Kidney relapses precipitated kidney failure in 71% of cases that progressed after the first year of follow-up. CONCLUSION: The novel AKRiS enhances the prediction of kidney failure in AAV with kidney involvement. As the prognostic yield of AKRiS decreases over time, a second calculation of AKRiS, including post-therapy kidney function, may improve its long-term performance.

The real-world use and effectiveness of avacopan in routine practice for the treatment of ANCA vasculitis. First experiences in Spain.

OBJECTIVES: ANCA-associated vasculitis (AAV) are chronic diseases with relapses that associate organic damage because of the disease and its treatment. Avacopan is a new treatment indicated for AAV. We present the first experiences with avacopan in Spain as part of an Early Access program. METHODS: Patients with AAV who started avacopan between June 2022-September 2023 were included. For comparison, a historical cohort of patients diagnosed with AAV around the same time and treated without avacopan was also included. RESULTS: 29 patients treated with avacopan were analyzed. Twelve patients (41.4%) were male, median age was 56 years. Most of patients were ANCA MPO positive (21/29, 72.4%). The most frequently affected organ was the kidney (23/29, 79.31%), with a mean eGFR of 23.2 ml/minMedian follow-up was 456.8 ± 181.7 days with a remission rate of 86.2%. eGFR increased from 23.2 ± 11.2-38.38 ± 18.55 ml/min after 12 months of diagnosis.2 patients had Adverse Events related to avacopan as severe neutropenia and a gastrointestinal affectation , 13 infections were reported and 1 death.Patients treated with avacopan received a significantly lower cumulative dose of prednisone at 6 and 12 months (p-values of 0.02 and <0.01, respectively) compared with historical controls. The evolution of GFR at 1 year of follow-up and the incidence of relapse were similar in both groups. CONCLUSION: The combination of avacopan in clinical practice presents a good safety profile and provides added value by contributing to the control of AAV activity, increase GFR, and removal of steroids.

FTY720 ameliorates experimental MPO-ANCA-associated vasculitis by regulating fatty acid oxidation via the neutrophil PPARα-CPT1a pathway.

OBJECTIVES: Increasing studies demonstrated the importance of C5a and anti-neutrophil cytoplasmic antibody (ANCA)-induced neutrophil activation in the pathogenesis of ANCA-associated vasculitis (AAV). Sphingosine-1-phosphate (S1P) acts as a downstream effector molecule of C5a and enhances neutrophil activation induced by C5a and ANCA. The current study investigated the role of a S1P receptor modulator, FTY720, in experimental autoimmune vasculitis (EAV) and explored the immunometabolism-related mechanisms of FTY720 in modulating ANCA-induced neutrophil activation. METHODS: The effects of FTY720 in EAV were evaluated by quantifying haematuria, proteinuria, crescent formation, tubulointerstitial injury and pulmonary haemorrhage. RNA sequencing of renal cortex and gene enrichment analysis were performed. The proteins of key identified pathways were analysed in neutrophils isolated from peripheral blood of patients with active AAV and normal controls. We assessed the effects of FTY720 on ANCA-induced neutrophil respiratory burst and neutrophil extracellular traps formation (NETosis). RESULTS: FTY720 treatment significantly attenuated renal injury and pulmonary haemorrhage in EAV. RNA sequencing analyses of renal cortex demonstrated enhanced fatty acid oxidation (FAO) and peroxisome proliferator-activated receptor (PPAR) signalling in FTY720-treated rats. Compared with normal controls, patients with active AAV showed decreased FAO in neutrophils. FTY720-treated differentiated HL-60 cells showed increased expression of carnitine palmitoyltransferase 1a (CPT1a) and PPARα. Blocking or knockdown of CPT1a or PPARα in isolated human neutrophils and HL-60 cells reversed the inhibitory effects of FTY720 on ANCA-induced neutrophil respiratory burst and NETosis. CONCLUSION: FTY720 attenuated renal injury in EAV through upregulating FAO via the PPARα-CPT1a pathway in neutrophils, offering potential immunometabolic targets in AAV treatment.

Prognostic significance of tubulointerstitial macrophage density in MPO-ANCA-associated glomerulonephritis: implications for renal outcomes.

OBJECTIVE: This study aimed to evaluate the density of tubulointerstitial macrophages with renal outcomes in patients with myeloperoxidase (MPO)-ANCA associated glomerulonephritis (MPO-ANCA GN). METHODS: This study analyzed patients with MPO-ANCA GN who had renal biopsies at Jinling Hospital. It looked at the density of CD68+ macrophages in the tubulointerstitium and examined correlations with serum creatinine levels, urinary protein levels, treatment regimen, and renal histologic class. The study used KM curves to show the impact of these factors on renal prognosis and conducted multivariate analyses with Cox proportional hazards regression models. RESULTS: A total of 172 patients with MPO-ANCA GN (median age: 50 y, 43.6% male) were included. Stratification of the cohort into tertiles was based on tubulointerstitial macrophage density. Significant differences in serum creatinine levels, induction treatment regimen, the rates of ESKD, and renal histologic class were observed between the three groups. Correlation analysis showed that induction treatment regimen and renal histologic class were correlated with tubulointerstitial macrophage density. Kaplan-Meier curves illustrated patients with a lower presence of CD68+ macrophages in the tubulointerstitium experienced significantly better renal survival compared with those with a higher presence. The higher levels of CD68+ macrophage infiltration were significantly associated with adverse renal outcomes. This association persisted after adjusting for potential confounders including baseline serum creatinine, histopathological class, and induction therapy modalities. CONCLUSIONS: The results of our study provide insight into the prognostic significance of macrophage infiltration in the tubulointerstitium in MPO-ANCA GN.

ANCA-associated scleritis: impact of ANCA on presentation, response to therapy and outcome.

OBJECTIVES: To describe the characteristics, treatment and outcome of isolated ANCA-associated scleritis at diagnosis compared with idiopathic scleritis with negative ANCA tests. METHODS: This retrospective multicentre case-control study was performed within the French Vasculitis Study Group (FVSG) network and in three French tertiary ophthalmologic centres. Data from patients with scleritis without any systemic manifestation and with positive ANCA results were compared with those of a control group of patients with idiopathic scleritis with negative ANCA tests. RESULTS: A total of 120 patients, including 38 patients with ANCA-associated scleritis and 82 control patients, diagnosed between January 2007 and April 2022 were included. The median follow-up was 28 months (IQR 10-60). The median age at diagnosis was 48 years (IQR 33-60) and 75% were females. Scleromalacia was more frequent in ANCA-positive patients (P = 0.027) and 54% had associated ophthalmologic manifestations, without significant differences. ANCA-associated scleritis more frequently required systemic medications, including glucocorticoids (76% vs 34%; P < 0.001), and rituximab (P = 0.03) and had a lower remission rate after the first- and second-line treatment. Systemic ANCA-associated vasculitis (AAV) occurred in 30.7% of patients with PR3- or MPO-ANCA, after a median interval of 30 months (IQR 16.3-44). Increased CRP >5 mg/l at diagnosis was the only significant risk factor of progression to systemic AAV [adjusted hazard ratio 5.85 (95% CI 1.10, 31.01), P = 0.038]. CONCLUSION: Isolated ANCA-associated scleritis is mostly anterior scleritis with a higher risk of scleromalacia than ANCA-negative idiopathic scleritis and is more often difficult to treat. One-third of patients with PR3- or MPO-ANCA scleritis progressed to systemic AAV.

Association of the AAV-PRO questionnaire with established outcome measures in AAV.

OBJECTIVES: The ANCA-associated vasculitis (AAV) patient-reported outcome (AAV-PRO) questionnaire was developed to capture the impact of AAV and its treatment. We investigated the association of specific AAV-PRO domains with disease activity and extent, damage, depression, health-related quality of life, and treatment. METHODS: In a prospective longitudinal study, AAV-PRO, Beck's depression inventory (BDI), Short Form 36 (SF-36), BVAS and Vasculitis Damage Index (VDI) were completed at baseline (t1) and after 3-6 months (t2). In addition, patient data (including diagnosis, therapies, relapses, and organ manifestations) were recorded. Data were analysed by t-tests and correlation-based regression analyses. RESULTS: A total of 156 patients with AAV participated. The mean BVAS at the time of enrolment was 1.4 ± 3.74. The median AAV-PRO domain scores were higher in patients reporting 'active disease' compared with those reporting 'in remission' (P < 0.001). In the correlation analyses, all AAV-PRO domain scores correlated strongly with the BDI (all r ≥ 0.319, all P ≤ 0.001) as well as with all eight SF-36 subdomains (all |r|≥0.267, all P ≤ 0.001). The regression analyses showed that AAV-PRO domains were strongly predicted by the BDI and SF-36 domains (|ß| ≥ 0.240 for the strongest predictor of each domain). In the longitudinal comparison (t1/t2), there were no significant changes in the overall results. CONCLUSION: Our data show convergent validity for all AAV-PRO subdomains, using the established questionnaires BDI and SF-36. The AAV-PRO domains scores were not correlated with clinician-derived instruments (including the BVAS and the VDI). Thus, we regard the AAV-PRO questionnaire as a valuable measure of outcomes that might complement traditional end-points in clinical trials.