Antineutrophil cytoplasmic antibody-associated vasculitides: could geographic patterns be explained by ambient ultraviolet radiation?

ANCA-Associated Vasculitis: Practical Issues in Management

ANCA associated vasculitides are multi-system autoimmune diseases which are increasing in prevalence. In this review we will discuss the clinical manifestations and review the management options. We highlight the various trials of induction and maintenance therapy and discuss the areas of unmet need. These include understanding which patients are at highest risk of relapse, clinical adaptation of improved biomarkers of disease activity and tools to discuss long term prognosis.

Profile, Healthcare Resource Consumption and Related Costs in ANCA-Associated Vasculitis Patients: A Real-World Analysis in Italy

INTRODUCTION

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are rare autoimmune diseases triggering inflammation of small vessels. This real-world analysis was focused on the most common AAV forms, granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), to describe patients' demographic and clinical characteristics, therapeutic management, disease progression, and the related economic burden.

METHODS

A retrospective analysis was conducted on administrative databases of a representative sample of Italian healthcare entities, covering approximately 12 million residents. Between January 2010 and December 2020, adult GPA patients were identified by payment waiver code or hospitalization discharge diagnosis, and MPA patients by payment waiver code with or without hospitalization discharge diagnosis. Clinical outcomes were evaluated through AAV-related hospitalizations, renal failure onset, and mortality. Economic analysis included healthcare resource utilization deriving from drugs, hospitalizations, and outpatient specialist services. The related mean direct costs year/patient were also calculated in patients stratified by presence/absence of glucocorticoid therapy and type of inclusion criterion (hospitalization/payment waiver code).

RESULTS

Overall, 859 AAV patients were divided into GPA (n = 713; 83%) and MPA (n = 146; 17%) cohorts. Outcome indicators highlighted a clinically worse phenotype associated with GPA compared to MPA. Cost analysis during follow-up showed tendentially increased expenditures in glucocorticoid-treated patients versus untreated (overall AAV: €8728 vs. €7911; GPA: €9292 vs. €9143; MPA: €5967 vs. €2390), mainly driven by drugs (AAV: €2404 vs. €874; GPA: €2510 vs. €878; MPA: €1881 vs. €854) and hospitalizations.

CONCLUSION

Among AAV forms, GPA resulted in a worse clinical picture, higher mortality, and increased costs. This is the first real-world pharmaco-economic analysis on AAV patients stratified by glucocorticoid use on disease management expenditures. In both GPA and MPA patients, glucocorticoid treatment resulted in higher healthcare costs, mostly attributable to medications, and then hospitalizations, confirming the clinical complexity and economic burden for management of patients with autoimmune diseases under chronic immunosuppression.

Can active sun exposure decrease the risk of giant cell arteritis and polymyalgia rheumatica in women?

Objectives

To study if active sun exposure among women affects the risk of developing GCA or PMR in a prospective cohort study with restricted latitudinal variability.

Methods

We linked the response to questions relating to sun exposure from the Melanoma Inquiry in Southern Sweden (MISS) prospective cohort study in women to the risk of developing GCA or PMR. Healthcare data were gathered from the Skåne Healthcare Register (SHR), covering all public healthcare consultations. The direct effect of active sun exposure on the risk of developing GCA or PMR was assessed using Cox proportional hazards models adjusted for covariates based on a directed acyclic graph.

Results

A total of 14 574 women were included in the study; 601 women were diagnosed with GCA or PMR (144 and 457, respectively) during the follow-up time. Women with moderate or high sun exposure were not less likely to develop GCA or PMR compared with women that indicated they avoided sun exposure [hazard ratio (HR) 1.2 (CI 0.9, 1.6) and 1.3 (0.9, 1.9), respectively] when adjusted for diabetes, hyperlipidaemia, hypertension, smoking, obesity and stratified by age. Similar patterns were observed when studying only GCA [HR 1.2 (CI 0.7, 2.3) and 1.3 (0.7, 2.6)] and only PMR [HR 1.3 (CI 0.9, 1.8) and 1.4 (0.9, 2.0)].

Conclusion

Active sun exposure did not affect the risk of developing GCA or PMR in women in a cohort with restricted latitudinal variability.

Environmental Triggers for Vasculitis

Systemic vasculitides are autoimmune diseases characterized by vascular inflammation. Most types of vasculitis are thought to result from antigen exposure in genetically susceptible individuals, suggesting a likely role for environmental triggers in these conditions. Seasonal and geographic variations in incidence provide insight into the potential role of environmental exposures in these diseases. Many data support infectious triggers in some vasculitides, whereas other studies have identified noninfectious triggers, such as airborne pollutants, silica, smoking, and heavy metals. We review the known and suspected environmental triggers in giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, Kawasaki disease, and antineutrophil cytoplasmic antibody-associated vasculitis.

Type of ANCA May Be Indispensable in Distinguishing Subphenotypes of Different Clinical Entities in ANCA-Associated Vasculitis

The traditional nomenclature system for classifying antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) based on clinical phenotype describes granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA) as distinct clinical entities. This classification has proved its expedience in clinical trials and everyday clinical practice; yet, a substantial overlap in clinical presentation still exists and often causes difficulties in prompt definition and clinical distinction. Additionally, new insights into the AAV pathogenesis point out that PR3 and MPO-AAV may not represent expressions of the same disease spectrum but rather two distinct disorders, as they display significant differences. Thus, it is supported that a classification based on ANCA serotype (PR3-ANCA, MPO-ANCA or ANCA-negative) could be more accurate and also closer to the nature of the disease compared to the phenotype-based one. This review aims to elucidate the major differences between PR3 and MPO-AAV in terms of epidemiology, pathogenesis, histological and clinical manifestations and response to therapeutic approaches.

Environmental factors influencing the risk of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of diseases characterized by inflammation and destruction of small and medium-sized blood vessels. Clinical disease phenotypes include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The incidence of AAV has been on the rise in recent years with advances in ANCA testing. The etiology and pathogenesis of AAV are multifactorial and influenced by both genetic and environmental factors, as well as innate and adaptive immune system responses. Multiple case reports have shown that sustained exposure to silica in an occupational environment resulted in a significantly increased risk of ANCA positivity. A meta-analysis involving six case-control studies showed that silica exposure was positively associated with AAV incidence. Additionally, exposure to air pollutants, such as carbon monoxide (CO), is a risk factor for AAV. AAV has seasonal trends. Studies have shown that various environmental factors stimulate the body to activate neutrophils and expose their own antigens, resulting in the release of proteases and neutrophil extracellular traps, which damage vascular endothelial cells. Additionally, the activation of complement replacement pathways may exacerbate vascular inflammation. However, the role of environmental factors in the etiology of AAV remains unclear and has received little attention. In this review, we summarized the recent literature on the study of environmental factors, such as seasons, air pollution, latitude, silica, and microbial infection, in AAV with the aim of exploring the relationship between environmental factors and AAV and possible mechanisms of action to provide a scientific basis for the prevention and treatment of AAV.

Secular Trends of Incidence, Prevalence, and Healthcare Economic Burden in ANCA-Associated Vasculitis: An Analysis of the 2002–2018 South Korea National Health Insurance Database

Objectives

The incidence and prevalence of AAV in Asia remain poorly understood, especially in a nationwide setting. This study investigated the incidence, prevalence, and healthcare burden of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in South Korea by analyzing a national database.

Methods

This study included patients with AAV identified from the National Health Insurance Service Database of South Korea from 2002 to 2018. Patients were diagnosed with AAV in a general or tertiary hospital and were registered in the individual payment beneficiaries program or were prescribed glucocorticoids. A calendar-based meteorological definitions were adopted to assess the differences in the incidence of AAV according to season. The average healthcare expenditure and patient outcomes of mortality and end-stage renal disease (ESRD) in patients with AAV were compared to 1:10 age, sex and residential area matched controls.

Results

A total of 2,113 patients [708, 638, and 767 with microscopic polyangiitis (MPA), granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis, respectively] were identified. The annual incidence and prevalence of AAV increased continuously, and MPA being the most common disease subtype after 2015. The highest incidence and prevalence of AAV was 0.48/100,000 person-years (PY) and 2.40/100,000 PY in 2017 and 2018, respectively. There were no significant differences in monthly and seasonal incidence of AAV. The average expense of medical care, overall mortality, and ESRD rates of patients with AAV were higher in patients with AAV than in controls, especially in the case of MPA.

Conclusion

An increasing trend of AAV diagnosis observed is consistent with the evidence that AAV is more common in recent years; however, a relatively lower incidence and prevalence was observed compared to that in Western countries. The higher medical cost and rates of mortality and ESRD in AAV emphasize the early recognition and implementation of optimal treatment for these patients.

The association between ambient UVB dose and ANCA-associated vasculitis relapse and onset

Background

The aetiology of ANCA-associated vasculitis (AAV) and triggers of relapse are poorly understood. Vitamin D (vitD) is an important immunomodulator, potentially responsible for the observed latitudinal differences between granulomatous and non-granulomatous AAV phenotypes. A narrow ultraviolet B spectrum induces vitD synthesis (vitD-UVB) via the skin. We hypothesised that prolonged periods of low ambient UVB (and by extension vitD deficiency) are associated with the granulomatous form of the disease and an increased risk of AAV relapse.

Methods

Patients with AAV recruited to the Irish Rare Kidney Disease (RKD) (n = 439) and UKIVAS (n = 1961) registries were studied. Exposure variables comprised latitude and measures of ambient vitD-UVB, including cumulative weighted UVB dose (CW-D-UVB), a well-validated vitD proxy. An n-of-1 study design was used to examine the relapse risk using only the RKD dataset. Multi-level models and logistic regression were used to examine the effect of predictors on AAV relapse risk, phenotype and serotype.

Results

Residential latitude was positively correlated (OR 1.41, 95% CI 1.14–1.74, p = 0.002) and average vitD-UVB negatively correlated (0.82, 0.70–0.99, p = 0.04) with relapse risk, with a stronger effect when restricting to winter measurements (0.71, 0.57–0.89, p = 0.002). However, these associations were not restricted to granulomatous phenotypes. We observed no clear relationship between latitude, vitD-UVB or CW-D-UVB and AAV phenotype or serotype.

Conclusion

Our findings suggest that low winter ambient UVB and prolonged vitD status contribute to AAV relapse risk across all phenotypes. However, the development of a granulomatous phenotype does not appear to be directly vitD-mediated. Further research is needed to determine whether sufficient vitD status would reduce relapse propensity in AAV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02834-6.

Systematic Review and Metaanalysis of Worldwide Incidence and Prevalence of Antineutrophil Cytoplasmic Antibody (ANCA) Associated Vasculitis

Objective: In this study, we aimed to evaluate the worldwide incidence and prevalence of ANCA-associated vasculitis (AAV). Methods: A systematic search of Medline and Embase was conducted until June 2020 for studies that analyzed the incidence and prevalence of patients aged >16 years diagnosed with AAV in different geographical areas. A meta-analysis was undertaken to estimate the pooled incidence per million person-years and prevalence per million persons in AAV overall and for each subtype of AAV: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The 95% confidence interval (CI) and I2 for heterogeneity were calculated. Results: The meta-analysis included 25 studies that met the inclusion criteria and covered a total of 4547 patients with AAV. Frequency increased over time. The global pooled incidence (95% CI) was 17.2 per million person-years (13.3−21.6) and the global pooled prevalence (95% CI) was 198.0 per million persons (187.0−210.0). The pooled incidence per million person-years for each AAV subtype varied from highest to lowest, as follows: GPA, 9.0; MPA, 5.9; and EGPA, 1.7. The individual pooled prevalence per million persons was, as follows: GPA, 96.8; MPA, 39.2; and EGPA, 15.6. AAV was more predominant in the northern hemisphere. By continent, a higher incidence in America and pooled prevalence of AAV was observed in America and Europe. Conclusion: The pooled incidence and prevalence of AAV seem to be increasing over time and are higher in the case of GPA. AAV was generally more frequent (incidence and prevalence) in the northern hemisphere.

Vitamin D levels in patients with small and medium vessel vasculitis

OBJECTIVES

To determine the prevalence of vitamin D deficiency in patients with small and medium vessel systemic vasculitis.

METHODS

In this cross-sectional study, 25-hydroxy (OH) vitamin D3 levels were measured in adult patients with systemic small and medium vessel vasculitis including antineutrophil cytoplasmic antibody-associated vasculitis (AAV), cryoglobulinaemic vasculitis (CryV), IgA vasculitis (IgAV) and polyarteritis nodosa (PAN), and age- and sex-matched healthy subjects (HS) and patients with rheumatoid arthritis (RA) as control groups. 25OH vitamin D3 levels<30ng/ml and <20ng/ml were regarded as insufficiency and deficiency, respectively.

RESULTS

Fifty-seven patients (42 AAV, 2 CryV, 8 IgA vasculitis, 5 PAN) with systemic vasculitis, 101 HS, and 111 RA patients were included. The mean 25OH vitamin D3 level was 21.8±14.2ng/mL in patients with vasculitis, 42.7±27.6ng/mL in HS (p<.001) and 20.1±18.47ng/mL in patients with RA (p=.54). Vitamin D insufficiency and deficiency were significantly higher in patients with systemic vasculitis compared to HS (75.4% vs 33.7%, p<.001; %50 vs 21.8%, p<.001, respectively). Vitamin D status was not different in patients with systemic vasculitis compared to RA. There was a negative correlation between vitamin D status and CRP levels (=-.364, p=.007). The multivariate logistic regression analysis showed that renal involvement was significantly associated with vitamin D deficiency/insufficiency in patients with vasculitis (OR 22.5 [95% CI 1.6-128.9].

CONCLUSION

Vitamin D deficiency and insufficiency are more frequent in patients with systemic small and medium vessel vasculitis and RA than HS. Renal involvement is one of the factors associated with vitamin D deficiency/insufficiency in patients with vasculitis.

ANCA-Associated Vasculitis in Latin America: A Systematic Literature Review: About Their Epidemiology and Their Clinical Features

ABSTRACT

Most of the existing literature, including epidemiological studies and clinical trials, on antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) include North American (mainly United States and Canada), European, and Asian populations. Few studies have focused on multiethnic populations such as the one from Latin America. Racial and ethnic differences in the incidence of AAV could partially explain the comparatively low number of AAV studies originating in Latin America. However, given the racial/ethnic diversity as well as socioeconomic differences existing in this region, better reporting of AAV presentations and outcomes in Latin America could highlight valuable gaps on the understanding and treatment of these patients. Recently, larger case series and studies have provided better clinical information regarding AAV patients in Latin American countries; however, further information is needed to address gaps such as risk factors, genetic profiles, clinical features, and predictors of clinical outcomes. For these reasons, we have performed a systematic literature review to enhance our understanding of AAV patients in Latin America. We have included 11 articles focused on the epidemiological and clinical features of AAV in Latin America; some similarities and differences with AAV in other regions are shown in these articles. We have identified differences in their prevalence across Latin American countries, which may reflect reporting bias or true ethnic differences among the countries. Our findings should encourage further investigation into AAV in Latin America; such studies will hopefully lead to the optimal management of these patients.

ANCA-associated vasculitis in Caucasian and Hispanics of the Inland Empire of Southern California

INTRODUCTION

ANCA-associated vasculitis is a disease with high morbidity and mortality which has shown to have different phenotypes in different ethnic and racial groups. This disease has been most frequently studied in Caucasians. We studied a group in Southern California where the Hispanics make up half of the population. We believe there will be different phenotypes between the two.

METHODS

A retrospective study of 114 patients was conducted at two tertiary care centers between 2003 and 2019. Demographic data, ICU admission, ANCA antibody status, BVAS on presentation, VDI per the last clinic visit, the number of hospitalizations, the number of follow-up years, and treatment were recorded. We calculated odds ratios for the categorical data and ran independent sample T test for the continuous data with alpha equal to 0.05 for statistical significance.

RESULTS

Difference was found in antibody status, disease presentation, morbidity, and age at diagnosis. Hispanics had greater number of AAV flares despite BVAS and VDI being comparable. Caucasians had more frequent follow-up. Hispanics had a 4.39 increase in odds of being admitted to the ICU, a 1.33 increased odds of developing acute respiratory failure, and a 67% increased odds of developing hemoptysis or pulmonary alveolar hemorrhage. Further, Hispanics had a 1.22 increase in odds of having ESRD.

CONCLUSIONS

Clinicians treating Hispanic patients with AAV should have a high index of suspicion for severe disease in this patient population. Further, epidemiologic and disparities research should be conducted to evaluate the discrepancy in outcomes in these groups. Key Points • This is the first study to examine the phenotype and severity of ANCA associated vasculitis in Southern California, a population which is comprised largely of Hispanics. • Hispanics in this population were found to be more likely to be admitted to the ICU, have more flares, reach end-stage renal disease, have severe pulmonary manifestations, and had fewer outpatient follow-up visits than their Caucasian counterparts. • Clinicians should have a high suspicion for more severe disease in Hispanics in this region when compared to Caucasians. • More research is needed to assess the degree social determinants of health contribute to these findings and if progress can be made with decreasing health disparities between these populations in this disease.

ANCA-associated renal vasculitis is associated with rurality but not seasonality or deprivation in a complete national cohort study

Background

Small studies suggest an association between ANCA-associated vasculitis (AAV) incidence and rurality, seasonality and socioeconomic deprivation. We examined the incidence of kidney biopsy-proven AAV and its relationship with these factors in the adult Scottish population.

Methods

Using the Scottish Renal Biopsy Registry, all adult native kidney biopsies performed between 2014 and 2018 with a diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) were identified. The Scottish Government Urban Rural Classification was used for rurality analysis. Seasons were defined as autumn (September–November), winter (December–February), spring (March–May) and summer (June–August). Patients were separated into quintiles of socioeconomic deprivation using the validated Scottish Index of Multiple Deprivation and incidence standardised to age. Estimated glomerular filtration rate and urine protein:creatinine ratio at time of biopsy were used to assess disease severity.

Results

339 cases of renal AAV were identified, of which 62% had MPA and 38% had GPA diagnosis. AAV incidence was 15.1 per million population per year (pmp/year). Mean age was 66 years and 54% were female. Incidence of GPA (but not MPA) was positively associated with rurality (5.2, 8.4 and 9.1 pmp/year in ‘urban’, ‘accessible remote’ and ‘rural remote’ areas, respectively; p=0.04). The age-standardised incidence ratio was similar across all quintiles of deprivation (p=ns).

Conclusions

Seasonality and disease severity did not vary across AAV study groups. In this complete national cohort study, we observed a positive association between kidney biopsy-proven GPA and rurality.

Classification of ANCA-associated vasculitis: differences based on ANCA specificity and clinicopathologic phenotype

The classification of vasculitis according to a schema with universal acceptance is challenging, given the heterogeneous and protean nature of these diseases. Formal nomenclature and classification criteria for anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) have suffered several changes since their first description; none provides comprehensive diagnostic and classification criteria. Different factors account for the difficulties in the classification of vasculitis, including the incomplete understanding of the pathogenesis, the multisystemic nature of the disease, the non-specific patterns of vascular involvement, the overlap between entities, and the presence of various classification systems. The present article reviews the classification of AAV considering different points of view, including clinical, serologic, pathogenetic, organ predilection, therapeutic, and prognostic factors, and provides perspectives on future challenges in the understanding of AAV. There is an unmet need for a unifying view of the disease spectrum that considers the constantly evolving paradigms.

ANCA-Associated Vasculitis: An Update

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a group of small vessel vasculitides characterized by granulomatous and neutrophilic tissue inflammation, often associated with the production of antibodies that target neutrophil antigens. The two major antigens targeted by ANCAs are leukocyte proteinase 3 (PR3) and myeloperoxidase (MPO). AAV can be classified into 3 categories based on patterns of clinical involvement: namely, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA). Clinically, AAV involves many organ systems including the lungs, kidneys, skin, and nervous system. The prognosis of AAV has improved dramatically due to advances in the understanding of its pathogenesis and treatment modalities. This review will highlight some of the recent updates in our understanding of the pathogenesis, clinical manifestations, and treatment options in patients with AAV focusing on kidney involvement.

Increasing incidence and prevalence of ANCA-associated vasculitis in Northern Norway

OBJECTIVE

ANCA-associated vasculitides (AAV) have increased in prevalence since the 1980s. We aimed to investigate the incidence and prevalence of AAV during a 15-year period from 1999 to 2013 in Northern Norway, looking for variations during this period.

METHODS

Patient records were retrieved from The Northern Norwegian Vasculitis Registry; in addition we searched all regional hospital databases. Patients diagnosed with AAV from 1999 through to 2013 were included. For prevalence data, patients residing in the area, but with AAV diagnosis prior to 1999, were also included. The diagnosis of AAV was based on the European Medicines Agency algorithm.

RESULTS

We identified 140 cases; 88 were classified as granulomatosis with polyangiitis (GPA), 37 as microscopic polyangiitis (MPA) and 15 as eosinophilic granulomatosis with polyangiitis (EGPA). Adult (age ≥15 years) annual incidence rates per million were as follows: for GPA 15.6 (95% CI: 12.5, 19.2), MPA 6.5 (95% CI: 4.6, 9.0), EGPA 2.7 (95% CI: 1.5, 4.5) and overall AAV 24.7 (95% CI: 20.8, 29.2). Incidences of MPA and overall AAV showed an increasing trend (P < 0.05). Adult point prevalence rates per million in 2013 were 261 (95% CI: 213, 316) for GPA, 58.2 (95% CI: 36.9, 87.3) for MPA, 32.9 (95% CI: 17.5, 56.3) for EGPA and 351 (95% CI: 296, 416) for overall AAV.

CONCLUSION

The incidence rate of GPA and the prevalence rates of GPA and EGPA are currently the highest reported. MPA increased significantly from a prior low incidence. The overall AAV annual incidence and prevalence are still increasing.

Vitamin D Levels in Patients With Small and Medium Vessel Vasculitis

OBJECTIVES

To determine the prevalence of vitamin D deficiency in patients with small and medium vessel systemic vasculitis.

METHODS

In this cross-sectional study, 25-hydroxy (OH) vitamin D3 levels were measured in adult patients with systemic small and medium vessel vasculitis including antineutrophil cytoplasmic antibody-associated vasculitis (AAV), cryoglobulinaemic vasculitis (CryV), IgA vasculitis (IgAV) and polyarteritis nodosa (PAN), and age- and sex-matched healthy subjects (HS) and patients with rheumatoid arthritis (RA) as control groups. 25OH vitamin D3 levels<30ng/ml and <20ng/ml were regarded as insufficiency and deficiency, respectively.

RESULTS

Fifty-seven patients (42 AAV, 2 CryV, 8 IgA vasculitis, 5 PAN) with systemic vasculitis, 101 HS, and 111 RA patients were included. The mean 25OH vitamin D3 level was 21.8±14.2ng/mL in patients with vasculitis, 42.7±27.6ng/mL in HS (p<.001) and 20.1±18.47ng/mL in patients with RA (p=.54). Vitamin D insufficiency and deficiency were significantly higher in patients with systemic vasculitis compared to HS (75.4% vs 33.7%, p<.001; %50 vs 21.8%, p<.001, respectively). Vitamin D status was not different in patients with systemic vasculitis compared to RA. There was a negative correlation between vitamin D status and CRP levels (=-.364, p=.007). The multivariate logistic regression analysis showed that renal involvement was significantly associated with vitamin D deficiency/insufficiency in patients with vasculitis (OR 22.5 [95% CI 1.6-128.9].

CONCLUSION

Vitamin D deficiency and insufficiency are more frequent in patients with systemic small and medium vessel vasculitis and RA than HS. Renal involvement is one of the factors associated with vitamin D deficiency/insufficiency in patients with vasculitis.

Serum vitamin D level correlates with disease activity and health-related quality of life in antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND AND OBJECTIVE

The association between vitamin D levels and disease activity has been established in patients with several autoimmune rheumatic diseases. We aimed to examine the association between vitamin D and disease activity of antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

Fifty-four AAV patients and 50 age- and sex-matched healthy controls without vitamin D supplements were included. Clinical and laboratory data were evaluated during the assessment of vitamin D levels. Two different forms of vitamin D in the sera-25(OH)D, which is the sum of 25(OH)D2 and 25(OH)D3, and 25(OH)D3, which only includes 25(OH)D in its D3 form-were measured, and the relationship between vitamin D and the obtained data was assessed. Variations in vitamin D levels relative to the season were also evaluated.

RESULTS

Patients with AAV demonstrated considerably lower 25(OH)D serum levels than healthy controls (16.0 vs. 20.4 ng/mL, p = 0.016), and the proportion of individuals with vitamin D deficiency was higher in patients with AAV than in healthy controls (68.5% vs. 48.0%, p = 0.035). Both serum 25(OH)D and 25(OH)D3 were positively associated with the 36-item Short-form Health Survey (SF-36) physical component summary and SF-36 mental component summary (MCS) scores. A negative correlation was observed between 25(OH)D and 25(OH)D3 serum levels and Birmingham vasculitis activity score (BVAS), C‑reactive protein (CRP), and white blood cell count. Linear regression analysis indicated haemoglobin and 25(OH)D levels to be independently associated with BVAS and CRP and 25(OH)D levels with SF-36 MCS score. No seasonal variations were observed in vitamin D levels.

CONCLUSION

The results from this study suggest that vitamin D levels could provide clinically useful information in AAV.

Environmental risk factors associated with ANCA associated vasculitis: A systematic mapping review

BACKGROUND

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a rare multi-system autoimmune disease, characterised by a pauci-immune necrotising small-vessel vasculitis, with a relapsing and remitting course. Like many autoimmune diseases, the exact aetiology of AAV, and the factors that influence relapse are unknown. Evidence suggests a complex interaction of polygenic genetic susceptibility, epigenetic influences and environmental triggers. This systematic mapping review focuses on the environmental risk factors associated with AAV. The aim was to identify gaps in the literature, thus informing further research.

METHODS

Articles that examined any environmental risk factor in AAV disease activity (new onset disease or relapse) were included. Studies had to make explicit reference to AAV, which includes the 3 clinico-pathological phenotypes (GPA, MPA and EGPA), rather than isolated ANCA-positivity. All articles identified were English-language, full manuscripts involving adult humans (>16 years). There was no restriction on publication date and all study designs, except single case reports, were included. The systematic search was performed on 9th December 2019, using the following databases: EMBASE, Medline (Ovid), Cochrane Library, CINAHL and Web of Science.

RESULTS

The search yielded a total of 2375 articles. 307 duplicates were removed, resulting in the title and abstract of 2068 articles for screening. Of these, 1809 were excluded. Thus, 259 remained for full-text review, of which 181 were excluded. 78 articles were included in this review. The most notable findings support the role of various pollutants - primarily silica and other environmental antigens released during natural disasters and through farming. Assorted geoepidemiological triggers were also identified including seasonality and latitude-dependent factors such as UV radiation. Finally, infection was tightly associated, but the exact microorganism(s) is not clear - Staphylococcus aureus is the most presently convincing.

CONCLUSION

The precise aetiology of AAV has yet to be elucidated. It is likely that different triggers, and the degree to which they influence disease activity, vary by subgroup (e.g. ANCA subtype, geographic region). There is a need for more interoperable disease registries to facilitate international collaboration and hence large-scale epidemiological studies, with novel analytical techniques.

ANCA-associated vasculitis

The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are a group of disorders involving severe, systemic, small-vessel vasculitis and are characterized by the development of autoantibodies to the neutrophil proteins leukocyte proteinase 3 (PR3-ANCA) or myeloperoxidase (MPO-ANCA). The three AAV subgroups, namely granulomatosis with polyangiitis (GPA), microscopic polyangiitis and eosinophilic GPA (EGPA), are defined according to clinical features. However, genetic and other clinical findings suggest that these clinical syndromes may be better classified as PR3-positive AAV (PR3-AAV), MPO-positive AAV (MPO-AAV) and, for EGPA, by the presence or absence of ANCA (ANCA⁺ or ANCA^-, respectively). Although any tissue can be involved in AAV, the upper and lower respiratory tract and kidneys are most commonly and severely affected. AAVs have a complex and unique pathogenesis, with evidence for a loss of tolerance to neutrophil proteins, which leads to ANCA-mediated neutrophil activation, recruitment and injury, with effector T cells also involved. Without therapy, prognosis is poor but treatments, typically immunosuppressants, have improved survival, albeit with considerable morbidity from glucocorticoids and other immunosuppressive medications. Current challenges include improving the measures of disease activity and risk of relapse, uncertainty about optimal therapy duration and a need for targeted therapies with fewer adverse effects. Meeting these challenges requires a more detailed knowledge of the fundamental biology of AAV as well as cooperative international research and clinical trials with meaningful input from patients.

High-Dose Vitamin D-Mediated Hypercalcemia as a Potential Risk Factor in Central Nervous System Demyelinating Disease

The exact cause of multiple sclerosis (MS) is unknown; however, it is considered to be an inflammatory disease of the central nervous system (CNS) triggered by a combination of both environmental and genetic factors. Vitamin D deficiency is also discussed as a possible disease-promoting factor in MS, as low vitamin D status is associated with increased formation of CNS lesions, elevated number of relapses and accelerated disease progression. However, it remains unclear whether this association is causal and related and most importantly, whether vitamin D supplementation in MS is of direct therapeutic benefit. Recently, we could show that in a murine model of MS, administration of a moderate vitamin D dose was of clinical benefit, while excessive vitamin D supplementation had a negative effect on disease severity. Of note, disease exacerbation was associated with high-dose vitamin D caused secondary hypercalcemia. Mechanistically dissecting this outcome, we found that hypercalcemia independent of vitamin D similarly triggered activation of disease-perpetuating T cells. These findings caution that vitamin D should be supplemented in a controlled and moderate manner in patients with MS and concomitantly highlight calcium as a novel potential MS risk factor by itself. In this review, we will summarize the current evidence from animal and clinical studies aiming to assess whether vitamin D may be of benefit in patients with MS. Furthermore, we will discuss any possible secondary effects of vitamin D with a particular focus on the role of calcium on immune cells and in the pathogenesis of CNS demyelinating disease.

Proteinase-3 and myeloperoxidase serotype in relation to demographic factors and geographic distribution in anti-neutrophil cytoplasmic antibody-associated glomerulonephritis

Background

In anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, antigen specificity varies between myeloperoxidase (MPO) and proteinase 3 (PR3). This has been reported to vary in relation to age, gender, geography and extrarenal manifestations. However, studies are difficult to compare as criteria for inclusion vary. The aim of this study was to investigate the relationship between ANCA serotype, latitude, ultraviolet (UV) radiation levels, age, gender and renal function at diagnosis in a large study with uniform inclusion criteria.

Methods

Patients with biopsy-proven ANCA-associated glomerulonephritis were identified from regional or nationwide registries in 14 centres in Norway, Sweden, the UK, the Czech Republic, Croatia, Italy and the USA during the period 2000-13. UV radiation levels for 2000-13 in Europe were obtained from the Swedish Meteorological and Hydrological Institute.

Results

A total of 1408 patients (45.2% PR3-ANCA) were included in the study. In univariable analysis, PR3-ANCA was significantly associated with male gender {odds ratio [OR] 2.12 [95% confidence interval (CI) 1.71-2.62]}, younger age [OR per year 0.97 (95% CI 0.96-0.98)] and higher glomerular filtration rate [OR per mL/min 1.01 (95% CI 1.01-1.02); P < 0.001] at diagnosis but not with latitude or UV radiation. In multivariable logistic regression analysis, latitude and UV radiation also became significant, with higher odds for PR3-ANCA positivity at northern latitudes/lower UV radiation levels. However, the latitudinal difference in MPO:PR3 ratio is smaller than differences previously reported concerning microscopic polyangiitis and granulomatosis with polyangiitis.

Conclusions

The ratio between PR3-ANCA and MPO-ANCA varies in glomerulonephritis with respect to age, gender, renal function and geographic latitude/UV radiation levels.

Evaluation of PR3-ANCA Status After Rituximab for ANCA-Associated Vasculitis

INTRODUCTION

The value of antineutrophil cytoplasmic antibody (ANCA) measurements among patients with an established diagnosis of ANCA-associated vasculitis (AAV) to assess disease activity or predict relapse remains controversial, but recent evidence suggests a possible role for rituximab-treated patients.

PATIENTS AND METHODS

All patients with active vasculitis and positive proteinase 3 (PR3)-ANCA who were starting a 2-year treatment course of rituximab for induction of remission at Addenbrooke's Hospital between January 2011 and January 2016 were included in this study. Common department practice consists of 6 g of rituximab given over 2 years, concomitant corticosteroids (0.5-1.0 mg/kg) with rapid taper over 3 months, and cessation of oral maintenance immunosuppressive agents at time of first rituximab dose. Clinical and laboratory data were collected retrospectively using electronic patient records.

RESULTS

Fifty-seven patients with current PR3-ANCA positivity were included in the analysis. Median follow-up was 59 months. PR3-ANCA negativity was achieved in 25 patients (44%) with a median time of 14 months. Clinical remission was achieved in 53 patients (93%) with a median time of 3 months. Among the 53 patients who achieved remission during follow-up, 24 (45%) relapsed with a median time to relapse of 36 months from remission. Both PR3-ANCA-negative status and 50% reduction in PR3-ANCA from baseline (as time-varying covariates) were significantly associated with a longer time to relapse (PR3-ANCA-negative status: hazards ratio, 0.08 [95% confidence interval, 0.01-0.63, p = 0.016]; 50% reduction in PR3-ANCA: hazards ratio, 0.25 [95% confidence interval, 0.18-0.99, p = 0.046]).

CONCLUSIONS

Achieving and maintaining PR3-ANCA negativity after rituximab was associated with longer-lasting remission.

The complexity of classifying ANCA-associated small-vessel vasculitis in actual clinical practice: data from a multicenter retrospective survey

The different sets of criteria for diagnosis or classification of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) lead to numerous overlapping and reclassified diagnoses in clinical practice. We designed this study to assess the difficulties in classifying patients with AAV. As a secondary objective, different variables were tested to predict prognosis. We conducted a retrospective chart review in a Western Spain multicentre survey. A total of 115 adult patients diagnosed with AAV from 2002 to 2013 and followed for at least 3 years were included. They were classified according to (1) Chapel Hill Consensus Conference (CHCC), (2) European Medicines Agency algorithm and (3) French Vasculitis Study Group/European Vasculitis Society phenotypes. Fifty-three patients (46%) had neither distinctive histopathological data of a single AAV definition nor any surrogate markers for granulomatous inflammation and thus did not fulfill any diagnostic criteria. Ocular, ear, nose, throat, skin, and lung involvement were more frequent with proteinase 3 (PR3) antibodies, whereas peripheral neuropathy was more frequent with myeloperoxidase (MPO) antibodies. When the disease was severe at diagnosis, the HR for mortality was 10.44. When induction treatment was not given in accordance with the guidelines, the HR for mortality was 4.00. For maintenance treatment, the HR was 5.49 for mortality and 2.48 for relapse. AAV classification is difficult because many patients had neither specific clinical data nor distinctive histological features of a single CHCC definition. A structured clinical assessment of patient severity is the best tool to guide the management of AAV.

Temporal and Cartographic Analyses of the Distribution within Spain of Mortality Due to Granulomatosis with Polyangiitis (1984⁻2016)

The aim is to conduct a descriptive, population-based study in order to assess temporal and spatial changes in mortality due to granulomatosis with polyangiitis (GPA) in Spain from 1984 to 2016. Mortality data were obtained from the Spanish Annual Death Registry. Deaths in which GPA was the underlying cause were selected using the 446.4 and M31.3 codes from the International Classification of Diseases, 9th and 10th revision. Annual average age at death and age-adjusted mortality rates were calculated. Geographic analysis was performed at municipality and district level. Variations in mortality according to the type of municipality (urban, agro-urban or rural), district and geographic location (degrees of latitude) were assessed using standardized mortality ratios (SMRs) and smoothed-SMRs. Over the whole period, 620 deaths due to GPA were identified. Age at death increased at an average annual rate of 0.78% over the period 1987–2016 (p < 0.05). Age-adjusted mortality rates increased by an annual average of 20.58% from 1984 to 1992, after which they fell by 1.91% a year (p < 0.05). The agro-urban category had the highest percentage (4.57%) of municipalities with a significantly higher GPA mortality rate than expected. Geographic analysis revealed four districts with a higher risk of death due to GPA, two in the North of Spain and two in the South. This population-based study revealed an increase in the age at death attributed to GPA. Age-adjusted mortality rates went up sharply until 1992, after which they started to decline until the end of the study period. Geographic differences in mortality risk were identified but further studies will be necessary to ascertain the reasons for the distribution of GPA disease.

Pathogenesis of ANCA-Associated Pulmonary Vasculitis

Antineutrophil cytoplasmic antibodies (ANCAs) are autoantibodies specific for antigens located in the cytoplasmic granules of neutrophils and lysosomes of monocytes. ANCAs are associated with a spectrum of necrotizing vasculitis that includes granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis. Pulmonary vasculitis and related extravascular inflammation and fibrosis are frequent components of ANCA vasculitis. In this review, we detail the factors that have been associated with the origin of the ANCA autoimmune response and summarize the most relevant clinical observations, in vitro evidence, and animal studies strongly indicating the pathogenic potential of ANCA. In addition, we describe the putative sequence of pathogenic mechanisms driven by ANCA-induced activation of neutrophils that result in small vessel necrotizing vasculitis and extravascular granulomatous necrotizing inflammation.

The frequency of ANCA-associated vasculitis in a national database of hospitalized patients in China

BACKGROUND

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is a group of life-threatening autoimmune diseases. The epidemiological data on AAV in China are limited. The aim of the present study is to investigate the frequency, geographical distribution, and ethnic distribution of AAV in hospitalized patients in China, and its association with environmental pollution.

METHODS

We investigated the hospitalized patients in a national inpatient database covering 54.1% tertiary hospitals in China from 2010 to 2015. Diagnosis of AAV was extracted according to the definition of International Classification of Diseases (ICD)-10 codes and free text. Variables from the front page of inpatient records were collected and analyzed, including frequency, geographic distribution, demographic characteristics and seasonal variations of AAV. The association between various environmental pollutants and frequency of AAV was further analyzed.

RESULTS

Among 43.7 million inpatients included in the study period, 0.25‰ (10,943) were diagnosed as having AAV. The frequency of AAV was relatively stable during the study period (from 0.34‰ in 2010 to 0.27‰ in 2015). The proportion of AAV increased with latitude (0.44‰ in Northern China and 0.27‰ in Southern China in 2015). Hospitalizations were mostly observed in winter (30.2%). The Dong population, an ethnic minority of the Chinese population, had the highest frequency of patients with AAV (0.67‰). We also found a positive association between the exposure to carbon monoxide and the frequency of AAV (R² = 0.172, p = 0.025). In Yunnan province, the frequency of AAV increased 1.37-fold after the Zhaotong earthquake, which took place in 2014.

CONCLUSIONS

Our present investigation of hospitalized patients provided epidemiological information on AAV in China for the first time. A spatial and ethnic clustering trend and an association between pollution and the frequency of AAV were observed.

Association between Sun Exposure, Vitamin D Intake, Serum Vitamin D Level, and Immunoglobulin G Level in Patients with Neuromyelitis Optica Spectrum Disorder

Background:

Neuromyelitis optica spectrum disorder (NMOSD) is a central nervous system inflammatory disorder in which immunoglobulin G (IgG) autoantibodies possibly play a pathogenic role against the aquaporin-4 water channel protein. Vitamin D may modulate B-cell function and decrease the IgG synthesis and may play a role in NMOSD as a crucial factor. The aim of this study was to investigate the relation between Vitamin D intakes from food, Vitamin D intake from sunlight exposure, blood Vitamin D levels, and IgG-neuromyelitis optica (NMO) level in serum of patients with NMOSD and NMO.

Method:

In this cross-sectional study, food Frequency Questionnaires (FFQ) and Sun Exposure Questionnaire (SEQ) were completed to evaluate of vitamin D intakes from food and sun light exposure. Moreover, serum levels of 25(OH) vitamin D3 and IgG-NMO were assessed in patients with NMOSD and NMO.

Results:

We assessed IgG-NMO levels in 29 patients with NMOSD that nine patients (n = 31%) were positive and for the rest it was negative. Sunlight exposure scale (P = 0.01) and 25(OH) D3 (P = 0.04) in IgG-NMO-negative patients were significantly more than patients with positive IgG-NMO. Age, gender, and latitude were not confounder variables. A positive significant correlation was observed between the sun exposure scale and serum levels of 25(OH) D3 in all participants (r = 0.747, P ≤ 0.001).

Conclusions:

Physiological variation in Vitamin D may apply a significant effect on IgG-NMO synthesis in patients with NMO. Vitamin D may have significant role in pathogenesis of NMOSD and NMO.

Clinical manifestations of granulomatosis with polyangiitis: key considerations and major features

BACKGROUND

Granulomatosis with polyangiitis (GPA) presents a wide spectrum of manifestations from the common respiratory symptoms to infrequent neurological and cardiac complications. The challenge in diagnosis and management makes the rapidly progressive disorder one of the most challenging dilemmas in clinical medicine.

METHOD

An extensive electronic literature search was done using multiple databases (e.g. PubMed) from January 2007 to August 2017 to gather information on the etiopathogenesis, clinical presentation, and current treatment management plan of GPA. The language used was English. Search items included 'Granulomatosis with Polyangiitis symptoms,' 'Wegener's Granulomatosis,' and 'Treatment of Granulomatosis with Polyangiitis' for the databases. Inclusion criteria consisted of published articles in the English language which reported on the clinical manifestations of GPA, as well as on the treatment of the disease. Exclusion criteria included articles that: (1) did not specifically report on GPA vasculitis but also focused on discussion of other vasculitis such as MPA or Churg-Strauss; (2) reported on treatment/symptoms of GPA prior to 2007.

RESULT

This review provides an overview of work undertaken in key areas of GPA research, including its complex multifactorial etiology, clinical manifestations, treatment strategies, and treatment-related adverse effects.

CONCLUSION

Major advances in the understanding and treatment of GPA over recent decades have contributed to the notable decline in morbidity and mortality of patients. The ultimate goal is an improved prognosis through outcome measures which assesses the disease control with minimal adverse effects of intensive immunosuppressive regimens, an integral part of the clinical approach to improve the quality of life of GPA patients.

Granulomatosis with polyangiitis in Northeastern Brazil: study of 25 cases and review of the literature

BACKGROUND

Little has been published about the epidemiology of Granulomatosis with polyangiitis (GPA) in South America, especially in the intertropical zone, and no epidemiological data from Brazil are available. The purpose of the present study was to draw a clinical and demographic profile of GPA patients living in Northeastern Brazil based on laboratory, histological and imaging findings, and evaluate the frequency of organic involvement.

METHODS

Clinical, epidemiological and treatment data of GPA patients were collected retrospectively and compared with the literature.

RESULTS

The cohort included 25 GPA patients (84% female) aged 45.8 ± 16.1 years. Renal and ear-nose-throat (ENT) manifestations were the most common (both 64%). One third (32%) of the patients had 24-h proteinuria > 1 g, 50% had creatinine clearance < 50 mL/min at the time of diagnosis, and 33% had recurrent kidney damage during disease progress. The affected organs included lungs (60%), joints (44%), skin (32%), peripheral nervous system (28%), eyes (28%) and heart (16%). ENT involvement (n = 16/64%) was less frequent in our region than in São Paulo (n = 115/85.8%). Renal (n = 16/64%) and pulmonary (n = 15/60%) involvement was less frequent in our region than in the U.K. (renal n = 30/90%; pulmonary n = 28/84.8%).

CONCLUSION

Most of our patients were female, presented the generalized form and were diagnosed late. The frequency of the main clinical manifestations (ENT, renal and pulmonary) was lower than that observed at higher latitudes, suggesting the existence of a Northeast Brazilian clinical and epidemiological profile and adding to our knowledge of this rare condition.

Galactosylation and Sialylation Levels of IgG Predict Relapse in Patients With PR3-ANCA Associated Vasculitis

OBJECTIVE

The objective of our study is to investigate the Fc glycosylation profiles of both antigen-specific IgG targeted against proteinase 3 (PR3-ANCA) and total IgG as prognostic markers of relapse in patients with Granulomatosis with Polyangiitis (GPA).

METHODS

Seventy-five patients with GPA and a PR3-ANCA rise during follow-up were included, of whom 43 patients relapsed within a median period of 8 (2-16) months. The N-glycan at Asn297 of affinity-purified and denatured total IgG and PR3-ANCA was determined by mass spectrometry of glycopeptides in samples obtained at the time of the PR3-ANCA rise and at the time of the relapse or time-matched during remission.

RESULTS

Patients with total IgG1 exhibiting low galactosylation or low sialylation were highly prone to relapse after an ANCA rise (HR 3.46 [95%-CI 1.73-6.96], p<0.0001 and HR 3.22 [95%-CI 1.52-6.83], p=0.002, respectively). In relapsing patients, total IgG1 galactosylation, sialylation and bisection significantly decreased and fucosylation significantly increased from the time of the PR3-ANCA rise to the relapse (p<0.0001, p=0.0087, p<0.0001 and p=0.0025), while the glycosylation profile remained similar in non-relapsing patients. PR3-ANCA IgG1 galactosylation, sialylation and fucosylation of PR3-ANCA IgG1 decreased in relapsing patients (p=0.0073, p=0.0049 and p=0.0205), but also in non-relapsing patients (p=0.0007, p=0.0114 and p=0.0002), while bisection increased only in non-relapsing patients (p<0.0001).

CONCLUSION

While Fc glycosylation profiles have been associated with clinically manifest autoimmune diseases, in the present study we show that low galactosylation and sialyation in total IgG1 but not PR3-ANCA IgG1 predicts disease reactivation in patients with GPA who experience an ANCA rise during follow-up. We postulate that glycosylation profiles may be useful in pre-emptive therapy studies using ANCA rises as guideline.

Seasonal Influence on the Risk of Relapse at a Rise of Antineutrophil Cytoplasmic Antibodies in Vasculitis Patients with Renal Involvement

Objective.

The objective of this study was to identify risk factors for a relapse at the time of an increase in antineutrophil cytoplasmic antibodies (ANCA) in patients with renal ANCA-associated vasculitis (AAV).

Methods.

All patients between January 2000 and November 2011 with renal AAV having an ANCA rise during remission were included. Differences in time to relapse since the ANCA rise were assessed using a Cox regression model. The level of 25-hydroxy Vitamin D (25(OH)D) was assessed at the ANCA rise and at a subsequent relapse or time-matched during remission.

Results.

Sixty patients had an ANCA rise, of whom 36 patients relapsed. Three risk factors were associated with a relapse at the time of the ANCA increase: previous disease activity not treated with cyclophosphamide or rituximab (HR 3.48, 95% CI 1.60–7.59), an ANCA rise during the fall season (HR 4.37, 95% CI 1.60–11.90), and an extended ANCA rise (HR 3.57, 95% CI 1.50–8.48). Levels of 25(OH)D significantly decreased during followup in relapsing patients, but not in patients who remained in remission (difference −6.3 ± 14.4, p = 0.017 vs 2.7 ± 16.3, p = 0.430).

Conclusion.

ANCA rises occurring during the fall season are more frequently followed by a relapse than ANCA rises occurring during other seasons. Although it is tempting to speculate that decreasing Vitamin D levels following the ANCA rise can be held responsible for the subsequent relapse, this remains to be determined.

Vitamin D Levels in Takayasu's Arteritis and a Review of the Literature on Vasculitides

OBJECTIVE

Takayasu's arteritis (TAK) is a chronic, large-vessel vasculitis. Vitamin D, as a steroidal hormone, has recently been shown to have immunoregulatory and immunosuppressive effects. Low vitamin D levels are demonstrated in various autoimmune disorders. The aim of this study is to investigate vitamin D levels in patients with TAK. A comprehensive review of vitamin D levels in systemic vasculitides (SVs) is also performed.

METHODS

The study included 36 patients with TAK, 28 patients with Behçet's disease (BD) as disease control and 30 sex-matched healthy controls. Plasma 25-hydroxy vitamin D (25(OH) vit D) levels were measured with high-performance liquid chromatography. "Deficiency" was defined as 25(OH) vit D levels below 25 nmol/l and "insufficiency" as below 50 nmol/l.

RESULTS

Plasma 25(OH) vit D levels were significantly lower in TAK patients (16.93 ± 10.62 nmol/l) than healthy controls (64.63 ± 21.82 nmol/l). Vitamin D level in BD patients (38.8 ± 20.9 nmol/l) is lower than healthy controls but higher than TAK patients. The frequency of vitamin D deficiency was 83.3% in patients with TAK compared to 3.3% in healthy controls. Plasma 25(OH) vit D levels were same between clinically active and inactive patients. In literature review, very few studies were found to investigate vitamin D in SVs.

CONCLUSION

We observed a high prevalence of vitamin D deficiency in patients with TAK. As various immune effects of vitamin D on mononuclear cells and arterial endothelium is shown, vitamin D deficiency can be a predisposing factor for immune activation in SV. We therefore suggest monitorization and replacement of vitamin D status in all TAK and other SV patients.

Classification, epidemiology and clinical subgrouping of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis

It is now 25 years since the first European studies on vasculitis--the anti-neutrophil cytoplasmic antibody (ANCA) standardization project. Over that period of time, there have been major developments in the classification of the vasculitides, which has permitted the conduct of high-quality epidemiology studies. Studying the epidemiology of rare diseases such as the ANCA-associated vasculitides (AAV) poses considerable challenges to epidemiologists. The first is the need for a clear definition of a case with good differentiation from similar disorders. The second is case capture. The vasculitides are rare, and therefore, a large population is required to determine the incidence and prevalence, and this poses questions of feasibility. A large population increases the risk of incomplete case detection but permits a reasonable number of cases to be collected in a practicable time frame, whereas a smaller population requires a much longer time frame to collect the necessary cases, which may also not be feasible. Statistical methods of capture-recapture analysis enable estimates to be made of the number of missing cases. The third is case ascertainment. The AAV are virtually always managed in secondary care, and therefore, hospital-based case ascertainment may be appropriate. Fourthly, the rarity of the conditions makes prospective case-control studies investigating risk factors difficult to conduct because the population size required to achieve statistical confidence is in excess of that which is readily available. Thus, much of the data on risk factors are derived from retrospective studies with inherent potential bias.

Proteinase 3-ANCA Vasculitis versus Myeloperoxidase-ANCA Vasculitis

In patients with GN or vasculitis, ANCAs are directed against proteinase 3 (PR3) or myeloperoxidase (MPO). The differences between PR3-ANCA-associated vasculitis (AAV) and MPO-AAV described in the past have been supplemented during the last decade. In this review, we discuss the differences between these two small-vessel vasculitides, focusing especially on possible etiologic and pathophysiologic differences. PR3-AAV is more common in northern parts of the world, whereas MPO-AAV is more common in southern regions of Europe, Asia, and the Pacific, with the exception of New Zealand and Australia. A genetic contribution has been extensively studied, and there is a high prevalence of the HLA-DPB1*04:01 allele in patients with PR3-AAV as opposed to patients with MPO-AAV and/or healthy controls. Histologically, MPO-AAV and PR3-AAV are similar but show qualitative differences when analyzed carefully. Clinically, both serotypes are difficult to distinguish, but quantitative differences are present. More organs are affected in PR3-AAV, whereas renal limited vasculitis occurs more often in patients with MPO-AAV. For future clinical trials, we advocate classifying patients by ANCA serotype as opposed to the traditional disease type classification.

Vitamin D and immunity

Vitamin D deficiency has been linked to an increased risk of a wide range of adverse health outcomes. The active form of vitamin D has an important role in calcium metabolism and in bone mineralisation, but the evidence for other health outcomes is mixed, with the strongest effects seen in the weakest epidemiological study designs. There are plausible pathways whereby vitamin D deficiency can impair immune function, resulting in both overactivity and increased risk of autoimmune disease, as well as immune suppression with poorer resistance to infection. Vitamin D status may influence the bacterial flora that constitute the microbiome and affect immune function through this route. Exposure of the skin to ultraviolet radiation causes the production of a range of chemicals, including vitamin D, and new research is exploring possible vitamin D-independent immunomodulatory pathways.

ANCA as a predictor of relapse: useful in patients with renal involvement but not in patients with nonrenal disease

The value of measuring ANCA during follow-up to predict a relapse is controversial. On the basis of recently obtained pathophysiologic insights, we postulated that measuring ANCA is useful in patients with renal involvement but is less valuable in patients with nonrenal disease. One hundred sixty-six consecutive patients with ANCA-associated vasculitis, positive for either proteinase 3 (PR3)-ANCA or myeloperoxidase (MPO)-ANCA, were included in our study, followed at regular intervals, and tested for PR3-ANCA and MPO-ANCA. In this cohort, 104 patients had renal involvement (72 with PR3-ANCA, 32 with MPO-ANCA) and 62 patients had nonrenal disease (36 with PR3-ANCA, 26 with MPO-ANCA). During an average (±SD) follow-up of 49±33 months and 18±14 ANCA measurements, 89 ANCA rises and 74 relapses were recorded. ANCA rises correlated with relapses in patients who presented with renal involvement (hazard ratio [HR], 11.09; 95% confidence interval [95% CI], 5.01 to 24.55), but in comparison, associated only weakly with relapses in patients who presented with nonrenal disease (HR, 2.79; 95% CI, 1.30 to 5.98). In conclusion, longitudinal ANCA measurements may be useful in patients with renal involvement but is less valuable in patients with nonrenal disease.

T cell-macrophage interactions and granuloma formation in vasculitis

Granuloma formation, bringing into close proximity highly activated macrophages and T cells, is a typical event in inflammatory blood vessel diseases, and is noted in the name of several of the vasculitides. It is not known whether specific properties of the microenvironment in the blood vessel wall or the immediate surroundings of blood vessels contribute to granuloma formation and, in some cases, generation of multinucleated giant cells. Granulomas provide a specialized niche to optimize macrophage-T cell interactions, strongly activating both cell types. This is mirrored by the intensity of the systemic inflammation encountered in patients with vasculitis, often presenting with malaise, weight loss, fever, and strongly upregulated acute phase responses. As a sophisticated and highly organized structure, granulomas can serve as an ideal site to induce differentiation and maturation of T cells. The granulomas possibly seed aberrant Th1 and Th17 cells into the circulation, which are known to be the main pathogenic cells in vasculitis. Through the induction of memory T cells, aberrant innate immune responses can imprint the host immune system for decades to come and promote chronicity of the disease process. Improved understanding of T cell-macrophage interactions will redefine pathogenic models in the vasculitides and provide new avenues for immunomodulatory therapy.

Plasma exchange induces vitamin D deficiency

BACKGROUND

Plasma exchange is used in the treatment of diseases mediated by pathogenic circulating proteins, or for transplant desensitization. Its non-targeted nature results in the depletion of physiologically important molecules, and it is often complicated by hypocalcaemia.

AIM

To determine the effects of plasma exchange on vitamin D binding protein (DBP) and associated vitamin D metabolites.

DESIGN

Single-centre prospective cohort study of 11 patients.

METHODS

DBP and vitamin D metabolites were measured before and immediately after five plasma exchanges, and 7 and 28 days after discontinuation of plasma exchange.

RESULTS

Plasma exchange reduced plasma DBP concentration from 196.9 ± 53.2 to 98.5 ± 34 μg/ml (P = 0.0001), 1,25-dihydroxyvitamin D from 103 ± 52 to 42 ± 4 pmol/l (P = 0.003) and 25-hydroxyvitamin D from 49.7 ± 29 to 22 ± 9.4 nmol/l (P = 0.0017), through their removal in effluent. After 7 days, DBP and 1,25-dihydroxyvitamin D were not significantly different from baseline, but 25-hydroxyvitamin D remained significantly lower after 7 days (26.4 ± 9.8 nmol/l, P = 0.02) and 28 days (30.8 ± 15.5 nmol/l, P = 0.048). Corrected calcium decreased from 2.23 ± 0.11 to 1.98 ± 0.08 mmol/l (P = 0.0007) immediately after five treatments. Plasma calcium was significantly associated with 1,25-dihydroxyvitamin D (r(2) = 0.79, P < 0.0001).

CONCLUSION

Plasma exchange induced an acute reversible decrease in plasma 1,25-dihydroxyvitamin D, DBP, calcium and a sustained decrease in plasma 25-hydroxyvitamin D.

Antineutrophil cytoplasmic autoantibodies: how are they detected and what is their use for diagnosis, classification and follow-up?

Antineutrophil cytoplasmic antibodies (ANCA) are traditionally detected by an indirect immunofluorescence technique. According to the international consensus on ANCA testing, ANCA should also be tested by antigen-specific tests for myeloperoxidase-ANCA and proteinase 3-ANCA. The direct noncompetitive enzyme-linked immunosorbent assay (ELISA) used to be the method of choice. Nowadays, these assays are called "first-generation" assays. Second-generation tests (capture ELISA) or third-generation tests (anchor ELISA) are more sensitive and specific for ANCA testing. We postulate that ANCA as detected by these newer ANCA tests may replace the need to perform indirect immunofluorescence-based assays. For classification of patients, ANCA serotype seems more important than classifying patients according to their clinical subtype, since genetics, clinical manifestations and response to therapy are more related to ANCA serotype than to clinical subtype. Detection of ANCA to monitor disease activity is still a controversial issue. Treatment based on ANCA levels is at present only experimentally performed in those patients who are treated with B-cell depletion therapy with rituximab. Future studies are needed to establish whether this way of monitoring patients is warranted.

Epidemiology and clinical features of systemic vasculitis

Different vasculitic syndromes present in different age groups. Immunoglobulin (Ig)A vasculitis and Kawasaki disease usually present in children whereas giant cell arteritis (GCA) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis usually present in the middle aged/elderly. In Northern Europe, granulomatosis with polyangiitis (GPA; Wegener's) is commoner than microscopic polyangiitis (MPA) and MPA is more common than eosinophilic granulomatosis with polyangiitis (EPGA; Churg-Strauss syndrome). In Southern Europe, MPA is commoner than GPA and in Japan MPA is much more common than GPA. Major differences exist worldwide in ANCA specificity which are not entirely related to different phenotypes. GPA, like GCA, has a cyclical pattern of onset suggesting possible infection as an aetiological agent. International studies have given important clues to possible aetiology including silica dust and infection and genetic influences, as shown by the recently published genome-wide association study which revealed that single-nucleotide polymorphisms associate more strongly with ANCA than clinical syndromes. A brief description of the main clinical features of ANCA-associated vasculitis is also given.

Fluctuations of MS births and UV-light exposure

BACKGROUND

Patients with multiple sclerosis (MS) are more frequently born in spring when compared to autumn. Fluctuation of UV-light has been hypothesized to drive this phenomenon.

AIM

To assess the correlation between fluctuation of sunlight and birth season in persons with MS.

METHODS

For this record-linkage study, we collected from the international MSBase and the Italian MS iMed-web databases the dates of birth of 11,415 patients with MS from 36 centres from 15 countries worldwide and compared these to dates of live-births from national registries. From all participating sites, we collected data on UV-light fluctuation and assessed its correlation with seasonal fluctuation in MS births.

RESULTS

Compared with the reference cohort, an increased proportion of persons with MS were born in spring and a decreased proportion in autumn (odds ratio (OR) to be born in spring versus autumn = 1.158, χ² = 36.347, P < 0.001). There was no significantly increased fluctuation of MS births with increased quartile of ambient UV-light fluctuation (Ptrend = 0.086).

CONCLUSION

Seasonal fluctuation of MS births as found in this worldwide cohort of patients with MS did not correlate with variation in seasonal fluctuation of UV-light. Most likely, it results from a complex interplay between fluctuation of sunlight, behavioural factors, other environmental factors and (epi)genetic factors.