The one-year infection risk among patients diagnosed with giant cell arteritis: use of antibiotics and hospitalisations.

OBJECTIVES: Patients with giant cell arteritis (GCA) primarily have their infections managed by primary care providers and hospitalisation is rarely necessary. Existing studies in GCA focus on infection-related hospitalisations only, whereas the use of antibiotic prescriptions is largely unknown. This study aims to examine the one-year overall infection risk among patients with GCA. METHODS: This nationwide observational cohort study included patients aged ≥50 years with a first-time GCA diagnosis in the Danish National Patient Registry (1996-2022). Patients with GCA were matched 1:10 by sex and date of birth with general population individuals and followed from date of diagnosis. Overall infections were defined as redeemed antibiotic prescriptions or infection-related hospitalisations. Utilising a pseudo-observation approach, we assessed 1-year cumulative incidence proportions (CIP), risk differences (RD), and relative risks (RR) of infections. RESULTS: The study included 17 773 incident patients with GCA and 177 730 reference individuals. Patients with GCA had a 1-year CIP of 52.4% (95% CI: 51.7-53.2) for overall infections and 17.6% (95% CI: 17.1-18.2) for infection-related hospitalisations. Compared with the reference cohort, patients with GCA had a RR of 1.40 (95% CI: 1.38-1.42) for overall infections and 2.71 (95% CI: 2.61-2.82) for infection-related hospitalisations. Additionally, higher cumulative glucocorticoid doses, advanced age (≥70 years), and higher comorbidity were associated with an increased risk of infections among patients with GCA. CONCLUSIONS: The use of antibiotic prescriptions and infection-related hospitalisations in the first year after a GCA diagnosis is high compared with the background population. The cumulative glucocorticoid dose is associated with the infection risk.

Stratified genetic analysis reveals sex differences in MPO-ANCA-associated vasculitis.

OBJECTIVE: To identify and genetically characterize subgroups of patients with ANCA-associated vasculitides (AAV) based on sex and ANCA subtype. METHODS: A previously established SNP dataset derived from DNA sequencing of 1853 genes and genotyping of 1088 Scandinavian cases with AAV and 1589 controls was stratified for sex and ANCA subtype and analysed for association with five top AAV SNPs. rs9274619, a lead variant at the HLA-DQB1/HLA-DQA2 locus previously associated with AAV positive for myeloperoxidase (MPO)-ANCA, was analysed for association with the cumulative disease involvement of ten different organ systems. RESULTS: rs9274619 showed a significantly stronger association to MPO-ANCA-positive females than males [P = 2.0 × 10-4, OR = 2.3 (95% CI 1.5, 3.5)], whereas proteinase 3 (PR3)-ANCA-associated variants rs1042335, rs9277341 (HLA-DPB1/A1) and rs28929474 (SERPINA1) were equally associated with females and males with PR3-ANCA. In MPO-ANCA-positive cases, carriers of the rs9274619 risk allele were more prone to disease engagement of eyes [P = 0.021, OR = 11 (95% CI 2.2, 205)] but less prone to pulmonary involvement [P = 0.026, OR = 0.52 (95% CI 0.30, 0.92)]. Moreover, AAV with both MPO-ANCA and PR3-ANCA was associated with the PR3-ANCA lead SNP rs1042335 [P = 0.0015, OR = 0.091 (95% CI 0.0022, 0.55)] but not with rs9274619. CONCLUSIONS: Females and males with MPO-ANCA-positive AAV differ in genetic predisposition to disease, suggesting at least partially distinct disease mechanisms between the sexes. Double ANCA-positive AAV cases are genetically similar to PR3-ANCA-positive cases, providing clues to the clinical follow-up and treatment of these patients.

Predictors of hypogammaglobulinemia in ANCA-associated vasculitis after a rituximab-based induction: a multicentre study.

OBJECTIVES: Rituximab has become the cornerstone of induction treatment in ANCA-associated vasculitis (AAV). B-cell depletion may increase the risk of hypogammaglobulinemia, potentially leading to severe infections. This study aims to assess factors associated with hypogammaglobulinemia in AAV patients treated with rituximab. METHODS: This retrospective cohort study included AAV patients treated with rituximab induction in 14 European centres. Severe adverse events (SAEs) were defined as episodes requiring hospitalization or intravenous antibiotics, malignancies, or death. Linear and logistic regression were used to identify predictors of IgG levels and of the risk of hypogammaglobulinemia, defined as IgG ≤7 g/l at 6 months. RESULTS: The study included 227 patients. IgG levels at 6 months were lower than baseline (P < 0.001). Patients requiring intravenous antibiotics during the first 6 months had lower IgG levels at 6 months (P = 0.004). Age [ß (95% CI): -0.23 (-0.38, -0.08) per 10 years, P = 0.003], oral glucocorticoid dose at induction [ß (95% CI): -0.37 (-0.51, -0.24) per sqrt-transformed mg prednisone, P < 0.001] and concomitant use of intravenous glucocorticoid pulses [ß (95% CI): -0.88 (-1.73, -0.02), P = 0.044] were associated with IgG levels at 6 months. Hypogammaglobulinemia was identified in 97 (42.7%) patients. In multivariable logistic regression, factors associated with the risk of hypogammaglobulinemia were age [OR (95% CI): 1.46 (1.15, 1.86) per 10 years, P = 0.002] and oral glucocorticoid dose at induction [OR (95% CI): 1.52 (1.23, 1.89) per 10 mg prednisone, P < 0.001]. CONCLUSIONS: In AAV patients treated with rituximab, hypogammaglobulinemia at 6 months after induction is common, and lower IgG levels are associated with serious infections. The risk of hypogammaglobulinemia in these patients increases with age and higher glucocorticoid doses.

A nationwide study of ocular manifestations leading to hospital contacts among patients with giant cell arteritis.

OBJECTIVES: To investigate the risk of ocular manifestations leading to hospital contacts among patients with giant cell arteritis (GCA). METHODS: A Danish, nationwide, register-based cohort study including 14,574 GCA patients diagnosed 1996-2018 and 145,740 general population referents, matched on sex and date of birth. Cumulative incidence proportions (CIPs) and relative risks (RRs) of ocular manifestations with 95% confidence intervals (CIs) were calculated using a pseudo-observation approach. RESULTS: A total of 1026/14,574 (7.0%) GCA patients were registered with ocular manifestations within ±1 year of the diagnosis; 392/1026 (38%) being before and 634/1026 (62%) after the GCA diagnosis, and 744/1026 (73%) were registered within ±1 month of the diagnosis. The diagnoses were 336/1026 (33%) retinal vascular occlusions, 300/1026 (29%) disorders of the optic nerve, 177/1026 (17%) visual impairment, 90/1026 (9%) diplopia, and 123/1026 (12%) amaurosis fugax. The CIP for ocular manifestations among GCA patients after 3, 6, and 12 months following the diagnosis were 4.0% (95% CI: 3.6-4.3), 4.2% (95% CI: 3.9-4.6), and 4.6% (95% CI: 4.2-4.9). The 1-year RR of ocular manifestations among GCA patients was 28.0 (95% CI: 24.0-32.7), with age above 70 years, male sex, and a positive temporal artery biopsy being risk factors. Treatment with low-dose aspirin was not associated with a reduced 1-year RR of incident ocular manifestations. CONCLUSIONS: In GCA, most cases of ocular manifestations leading to hospital contacts occur close to the time of diagnosis, with over one-third of cases occurring before the diagnosis, emphasizing the need for early recognition and treatment.

The utility of transbronchial lung biopsies to guide the treatment decision in patients with rheumatic inflammatory diseases: a retrospective cross-sectional study.

The role of transbronchial lung biopsies (TBB) in the diagnostic workup of systemic inflammatory rheumatic disease-associated interstitial lung disease (SIRD-ILD) is unclear and TBB is not generally recommended. The study objective was to examine the utility of TBB to guide treatment in a population of patients with SIRD-ILD. All patients from the Department of Rheumatology, Rigshospitalet, Denmark, who had TBB performed, from 2002 to 2016 were identified. Patient demographics as well as smoking status, previous lung disease, pulmonary function test, SIRD-diagnosis, imaging results and immunomodulatory therapy pre- and post-bronchoscopy were obtained. Histology findings were used to dichotomize patients into a high-inflammatory group or a low-inflammatory group. The high-inflammation group primarily consisted of non-specific interstitial pneumonia, organizing pneumonia, lymphocytic infiltrating pneumonia and granulomatous inflammation whereas the low inflammation group primarily consisted of histological findings of usual interstitial pneumonitis and biopsies describing fibrosis and/or sparse unspecific inflammation. Therapeutic consequence was defined as intensification of therapy. Differences in treatment intensification were calculated using a binominal logistic regression model. Ninety-six patients had TBB performed. Biopsies from 55 patients were categorized as high inflammatory and 41 as low inflammatory, respectively. In the high-inflammatory group, 38 (69%) had their therapy intensified compared to 6 (14%) in the low-inflammatory group (Odds ratio 8.0, 95% confidence limits 3.2-20.0, P < 0.001). No procedure-related complications were registered. TBB findings can guide treatment strategy in SIRD-ILD patients with suspected activity in the pulmonary disease. TBB appears safe and could be considered as part of the diagnostic workup.

Risk of Cancer Among Sarcoidosis Patients With Biopsy-verified Nonnecrotizing Granulomatous Inflammation: Population-based Cohort Study.

OBJECTIVE: To assess the long-term risk of hematologic cancers, invasive solid tumors, and nonmelanoma skin cancer (NMSC) among sarcoidosis patients with biopsy-verified nonnecrotizing granulomatous inflammation. METHODS: We used Danish administrative registers with nationwide coverage to construct a cohort of 3892 patients with sarcoidosis and an age- and sex-matched comparison cohort of 38,920 population controls. For all patients, a biopsy demonstrating nonnecrotizing granulomatous inflammation had been obtained from the lower respiratory tract at the time of diagnosis. Study outcome was time to diagnosis of cancer. Follow-up began at time of sarcoidosis diagnosis and continued for up to 10 years. We calculated hazard ratios (HRs) as estimates of the cancer risk among the patients with sarcoidosis relative to that among the population controls and used cumulative incidence functions to calculate absolute 10-year risk estimates. RESULTS: We observed an increased long-term risk of hematologic cancers (HR during the first 2 years of follow-up: 2.71 [95% CI 1.18-6.25]; HR after > 2 years of follow-up: 2.12 [95% CI 1.29-3.47]) and NMSC (HR after > 2 years of follow-up: 1.82 [95% CI 1.43-2.32]) among the patients with sarcoidosis. An increased risk of invasive solid tumors was only observed during the first 2 years (HR 1.55, 95% CI 1.18-2.04). Compared with the population controls, the patients with sarcoidosis had an increased absolute 10-year risk of hematologic cancers (risk difference 0.56%, 95% CI 0.11-1.01%) and NMSC (risk difference 1.58%, 95% CI 0.70-2.47%). CONCLUSION: Sarcoidosis patients with biopsy-verified nonnecrotizing granulomatous inflammation have an increased long-term risk of hematologic cancers and NMSC compared with the general population.

Long-term Risk of Heart Failure and Other Adverse Cardiovascular Outcomes in Granulomatosis With Polyangiitis: A Nationwide Cohort Study.

OBJECTIVE: To examine the long-term rates of heart failure (HF) and other adverse cardiovascular (CV) outcomes in a nationwide cohort of patients diagnosed with granulomatosis with polyangiitis (GPA) compared with the general population. METHODS: Using Danish nationwide registries, patients with newly diagnosed GPA were identified and matched 1:4 by age, sex, and comorbidities with subjects from the general population. Outcomes were compared using Cox regression. Due to violation of the proportional hazard assumption, landmark analyses for the first year and from 1 year were performed. RESULTS: Of the 1923 patients with GPA, 1781 patients (median age 59 yrs, 47.9% men) were matched with 7124 subjects from the general population. The median follow-up was 6.4 years. The absolute 10-year risk of HF was 6.8% (95% CI 5.5-8.2%) for patients with GPA and 5.9% (5.3-6.6%) for the general population. During the first year after diagnosis, GPA was associated with a significantly higher rate of HF (hazard ratio [HR] 3.60, 95% CI, 2.28-5.67) and other adverse outcomes, including atrial fibrillation/flutter (HR 6.50, 95% CI 4.43-9.55) and ischemic stroke (HR 3.24, 95% CI 1.92-5.48), compared with the general population. After the first year, GPA was not associated with higher rates of HF or other CV outcomes compared with the general population, except atrial fibrillation/flutter (HR 1.38, 95% CI 1.12-1.70). CONCLUSION: During the first year after diagnosis, the rates of HF and other CV outcomes were higher in patients with GPA compared with the general population. However, after the first year, the rates of HF and other CV outcomes, except atrial fibrillation/flutter, were similar to those in the general population.

Identification and functional characterization of a novel susceptibility locus for small vessel vasculitis with MPO-ANCA.

OBJECTIVE: To identify and characterize genetic loci associated with the risk of developing ANCA-associated vasculitides (AAV). METHODS: Genetic association analyses were performed after Illumina sequencing of 1853 genes and subsequent replication with genotyping of selected single nucleotide polymorphisms in a total cohort of 1110 Scandinavian cases with granulomatosis with polyangiitis or microscopic polyangiitis, and 1589 controls. A novel AAV-associated single nucleotide polymorphism was analysed for allele-specific effects on gene expression using luciferase reporter assay. RESULTS: PR3-ANCA+ AAV was significantly associated with two independent loci in the HLA-DPB1/HLA-DPA1 region [rs1042335, P = 6.3 × 10-61, odds ratio (OR) 0.10; rs9277341, P = 1.5 × 10-44, OR 0.22] and with rs28929474 in the SERPINA1 gene (P = 2.7 × 10-10, OR 2.9). MPO-ANCA+ AAV was significantly associated with the HLA-DQB1/HLA-DQA2 locus (rs9274619, P = 5.4 × 10-25, OR 3.7) and with a rare variant in the BACH2 gene (rs78275221, P = 7.9 × 10-7, OR 3.0), the latter a novel susceptibility locus for MPO-ANCA+ granulomatosis with polyangiitis/microscopic polyangiitis. The rs78275221-A risk allele reduced luciferase gene expression in endothelial cells, specifically, as compared with the non-risk allele. CONCLUSION: We identified a novel susceptibility locus for MPO-ANCA+ AAV and propose that the associated variant is of mechanistic importance, exerting a regulatory function on gene expression in specific cell types.

Long-Term Cardiovascular Outcomes in Systemic Lupus Erythematosus.

BACKGROUND: Data on long-term cardiovascular outcomes in systemic lupus erythematosus (SLE) are sparse. OBJECTIVES: This study sought to examine the long-term risk and prognosis associated with cardiovascular outcomes, including heart failure (HF), in patients with SLE. METHODS: Using Danish administrative registries, risks of outcomes were compared between SLE patients (diagnosed 1996 to 2018, no history of cardiovascular disease) and age-, sex-, and comorbidity-matched control subjects from the background population (matched 1:4). Furthermore, mortality following HF diagnosis was compared between SLE patients developing HF and age- and sex-matched non-SLE control subjects with HF (matched 1:4). RESULTS: A total of 3,411 SLE patients (median age: 44.6 years [25th to 75th percentile: 31.9 to 57.0 years]; 14.1% men) were matched with 13,644 control subjects. The median follow-up was 8.5 years (25th to 75th percentile: 4.0 to 14.4 years). Absolute 10-year risks of outcomes were: HF, 3.71% (95% confidence interval [CI]: 3.02% to 4.51%) for SLE patients, 1.94% (95% CI: 1.68% to 2.24%) for control subjects; atrial fibrillation, 4.35% (95% CI: 3.61% to 5.18%) for SLE patients, 2.82% (95% CI: 2.50% to 3.16%) for control subjects; ischemic stroke, 3.75% (95% CI: 3.06% to 4.54%) for SLE patients, 1.92% (95% CI: 1.66% to 2.20%) for control subjects; myocardial infarction, 2.17% (95% CI: 1.66% to 2.80%) for SLE patients, 1.49% (95% CI: 1.26% to 1.75%) for control subjects; venous thromboembolism, 6.03% (95% CI: 5.17% to 6.98%) for SLE patients, 1.68% (95% CI: 1.44% to 1.95%) for control subjects; and the composite of implantable cardioverter-defibrillator implantation/ventricular arrhythmias/cardiac arrest, 0.89% (95% CI: 0.58% to 1.31%) for SLE patients, 0.30% (95% CI: 0.20% to 0.43%) for control subjects. SLE with subsequent HF was associated with higher mortality compared with HF without SLE (adjusted hazard ratio: 1.50; 95% CI: 1.08 to 2.08). CONCLUSIONS: SLE patients had a higher associated risk of HF and other cardiovascular outcomes compared with matched control subjects. Among patients developing HF, a history of SLE was associated with higher mortality.

Mortality and cardiovascular morbidity among patients diagnosed with Takayasu's arteritis: a Danish nationwide cohort study.

OBJECTIVES: To assess the long-term mortality and risk of cardiovascular events (CVE) among Danish patients with Takayasu's arteritis (TAK). METHODS: Administrative registers with nationwide coverage were used to identify patients diagnosed with TAK in Denmark during 1994-2014 and construct an age- and gender-matched cohort of population-controls. CVE were identified by means of hospital discharge diagnoses and categorised as major or minor, based on severity. Cox regression analyses were used to calculate hazard ratios (HRs) for death and first-time hospitalisations for CVE as a measure of relative risk. RESULTS: 79 patients with TAK were identified, corresponding to an incidence rate of 0.7 (95% confidence interval (CI): 0.6-0.9)/million/year. Median duration of follow-up in the TAK cohort was 6.4 (IQR: 3.7-11) years. Mortality was significantly higher among the TAK patients than among the population controls during the first 3 years of follow-up [HR for death: 8.0 (95% CI: 3.0-21)], but not after >3 years [HR for death: 0.5 (95% CI: 0.1-3.5)]. Risk of CVE was significantly increased among TAK patients after ≤3 years [HR for major CVE: 12 (95% CI: 3.8-37), HR for minor CVE: 19 (95% CI: 7.5-50)] as well as after >3 years [HR for major CVE: 7.6 (95% CI: 2.8-21), HR for minor CVE: 3.0 (95% CI: 1.01-9.0)]. CONCLUSIONS: Compared to the general population, patients with TAK experience markedly increased mortality during early follow-up periods. The long-term risk of CVE is high among patients affected by the disease.

Adrenal insufficiency is seen in more than one-third of patients during ongoing low-dose prednisolone treatment for rheumatoid arthritis.

OBJECTIVE: Patients receiving long-term glucocorticoid treatment are at risk of developing adrenal insufficiency during treatment. We investigated the prevalence of prednisolone-induced adrenal insufficiency in the particular clinical situation where patients receive ongoing low-dose (5 mg/day) prednisolone treatment, a dose by itself too low to cover glucocorticoid needs during stress. DESIGN AND METHODS: Cross-sectional study in 42 patients with rheumatoid arthritis (29 women, aged 36-86 years) treated with 5 mg prednisolone/day, who had received prednisolone for ≥6 months (median: 66, range: 6-444 months). Adrenal function was evaluated by a 250 µg Synacthen test performed after mean 48.7 h prednisolone pause. Local assay-specific cut-off for normal adrenal function was P-cortisol ≥420 nmol/L 30 min after Synacthen injection. RESULTS: Overall, 20 of the 42 patients (48%, 95% CI: 33-62%) had an insufficient adrenal response to the Synacthen test. Including only patients who had not received concomitant treatment with any other glucocorticoid formulas within the last 3 months, 13 of 33 patients (39%, 95% CI: 25-56%) had an insufficient response. Adrenocorticotrophic hormone (ACTH) concentrations were generally low and anti-adrenal antibodies were negative indicating secondary adrenal insufficiency as the most likely diagnosis. There was no correlation between duration of treatment and 30 min P-cortisol (P = 0.62). Adrenal function did not depend on sex or seropositivity of rheumatoid arthritis. CONCLUSION: We demonstrate a high prevalence of adrenal insufficiency during ongoing low-dose prednisolone treatment. The results urge to increase focus on the condition to ensure identification and correct management of insufficient patients during stress and withdrawal. Strategies for adrenal function evaluation during ongoing low-dose glucocorticoid treatment need to be established.

A multicentre study to improve clinical interpretation of proteinase-3 and myeloperoxidase anti-neutrophil cytoplasmic antibodies.

Objective: The objective of this multicentre study was to improve the clinical interpretation of PR3- and MPO-ANCAs as an adjunct for the diagnosis of ANCA-associated vasculitis (AAV) by defining thresholds and test result intervals based on predefined specificities and by calculating test result interval-specific likelihood ratios (LRs). Methods: Eight different PR3- and MPO-ANCA immunoassays from seven companies were evaluated using 251 diagnostic samples from AAV patients and 924 diseased controls. Results: Thresholds for antibody levels were determined based on predefined specificities (95, 97.5, 99 and 100%) and used to delimit test result intervals. Test result interval-specific LRs were determined. For all assays, the LR for AAV increased with increasing antibody level. For all but one immunoassay, high antibodies levels (associated with LR >55) were found in a substantial fraction (>65%) of patients. The area under the curve (AUC) of receiver operating characteristics analysis of a diagnostic approach in which positive results were confirmed by IIF or another immunoassay was not substantially higher than the AUC of performing immunoassay only. The highest AUC was found when immunoassay was combined with another immunoassay or with IIF. Conclusion: To diagnose AAV based on PR3- and MPO-ANCA, it is useful to define thresholds for antibody levels and to assign test result interval-specific LRs. Higher antibody levels are associated with a higher likelihood for disease. Such information improves clinical interpretation.

Risk of Diabetes Mellitus among Patients Diagnosed with Giant Cell Arteritis or Granulomatosis with Polyangiitis: Comparison with the General Population.

OBJECTIVE: Patients with organ- or life-threatening vasculitis receive high cumulative glucocorticoid (GC) doses during their disease course. GC have diabetogenic effects, but the risk of diabetes mellitus (DM) related to vasculitis therapy is not well characterized. We assessed the DM risk among patients diagnosed with giant cell arteritis (GCA) or granulomatosis with polyangiitis (GPA), i.e., patients with relatively common forms of systemic vasculitis. METHODS: We used Danish healthcare registries to identify 1682 patients diagnosed with GCA and 342 patients diagnosed with GPA from 1997 to 2015 and to obtain information regarding medication exposures. Each patient with vasculitis was matched with 9 population controls. Date of new-onset DM was defined as date of first claimed prescription for an antidiabetic drug. We used Cox regression analyses to calculate incidence rate ratios (IRR) for DM as a measure of the DM risk among patients relative to population controls. Logistic regression was used to study the association between prednisolone/prednisone (PRED) dose and DM. RESULTS: Median duration of followup was 6.5 years [interquartile range (IQR) 2.6-10.4] in the GCA cohort and 5.8 years (IQR 1.7-10.6) in the GPA cohort. During the first year after diagnosis of vasculitis, the IRR for DM was 7.0 (95% CI 5.2-9.3) among patients with GCA and 10.4 (95% CI 4.4-24) among patients with GPA. IRR for DM were not significantly increased in either cohort during later followup periods. Within the first year, treatment with high cumulative prednisolone/PRED doses was associated with new-onset DM among the patients with vasculitis. CONCLUSION: Patients diagnosed with GCA or GPA have a markedly increased risk of new-onset DM during early treatment phases.

Detection of antineutrophil cytoplasmic antibodies (ANCAs): a multicentre European Vasculitis Study Group (EUVAS) evaluation of the value of indirect immunofluorescence (IIF) versus antigen-specific immunoassays.

OBJECTIVE: This multicentre study was performed to evaluate the diagnostic accuracy of a wide spectrum of novel technologies nowadays available for detection of myeloperoxidase (MPO) and proteinase 3 (PR3)-antineutrophil cytoplasmic antibodies (ANCAs). METHODS: Sera (obtained at the time of diagnosis) from 251 patients with ANCA-associated vasculitis (AAV), including granulomatosis with polyangiitis and microscopic polyangiitis, and from 924 disease controls were tested for the presence of cytoplasmic pattern/perinuclear pattern and atypical ANCA (A-ANCA) by indirect immunofluorescence (IIF) (at two sites) and for the presence of PR3-ANCA and MPO-ANCA by eight different immunoassays. RESULTS: The area under the curve (AUC) of the receiver operating characteristic curve to discriminate AAV from controls was 0.923 (95% CI 0.902 to 0.944) and 0.843 (95% CI 0.814 to 0.871) for the two IIF methods. For the antigen-specific immunoassays, the AUC varied between 0.936 (95% CI 0.912 to 0.960) and 0.959 (95% CI 0.941 to 0.976), except for one immunoassay for which the AUC was 0.919 (95% CI 0.892 to 0.945). CONCLUSIONS: Our comparison of various ANCA detection methods showed (i) large variability between the two IIF methods tested and (ii) a high diagnostic performance of PR3-ANCA and MPO-ANCA by immunoassay to discriminate AAV from disease controls. Consequently, dual IIF/antigen-specific immunoassay testing of each sample is not necessary for maximal diagnostic accuracy. These results indicate that the current international consensus on ANCA testing for AAV needs revision.

MicroRNA-941 Expression in Polymorphonuclear Granulocytes Is Not Related to Granulomatosis with Polyangiitis.

Jumonji Domain-Containing Protein 3 (JMJD3)/lysine demethylase 6B (KDM6B) is an epigenetic modulator that removes repressive histone marks on genes. Expression of KDM6B mRNA is elevated in leukocytes from patients with ANCA-associated vasculitis (AAV) and has been suggested to be the reason for higher proteinase 3 (PR3) mRNA expression in these cells due to derepression of PRTN3 gene transcription. MicroRNA-941 (miR-941) has been shown to target KDM6B mRNA and inhibit JMJD3 production. We therefore investigated whether polymorphonuclear granulocytes (PMNs) from patients suffering from granulomatosis with polyangiitis (GPA) have lower expression of miR-941 than healthy control donors as a biological cause for higher JMJD3 levels. We found no significant difference in the degree of maturation of PMNs from GPA patients (n = 8) and healthy controls (n = 11) as determined from cell surface expression of the neutrophil maturation marker CD16 and gene expression profile of FCGR3B. The expression of PRTN3 and KDM6B mRNAs and miR-941 was not significantly different in GPA patients and healthy controls. Transfection of pre-miR-941 into the neutrophil promyelocyte cell line PLB-985 cells did not result in reduction of the KDM6B mRNA level as shown previously in a hepatocellular carcinoma cell line. The amount of PR3 in PMNs from GPA patients and healthy controls was comparable. In conclusion, we found that PRTN3 mRNA, KDM6B mRNA, and miR-941 expression levels in PMNs do not differ between GPA patients and healthy controls, and that miR-941 does not uniformly regulate KDM6B mRNA levels by inducing degradation of the transcript. Thus, decreased miR-941 expression in PMNs cannot be part of the pathogenesis of GPA.