Prevalence and spectrum of rheumatic diseases associated with proteinase 3-antineutrophil cytoplasmic antibodies (ANCA) and myeloperoxidase-ANCA

Pathology of Pulmonary Vascular Disease with Radiologic Correlation

Pulmonary hypertensive changes are commonly seen by the surgical pathologist, but the majority represents secondary changes due to some process extrinsic to the lung. Some primary, or idiopathic, vascular diseases result in unique pathologic changes including the plexiform lesion and venous hypertensive changes. Thromboembolic disease also shows unique pathologic features. Diffuse alveolar hemorrhage, vasculitis, and capillaritis often overlap, but may represent separate, distinct pathologic processes. Lastly, alveolar capillary dysplasia with misalignment of pulmonary veins, as well as chronic lung allograft vasculopathy, present as unique pathologies in the neonate and posttransplant recipient, respectively.

Diagnostic accuracy of ANCA serology in ANCA-associated vasculitis with renal involvement

BACKGROUND

Pauci-immune glomerulonephritis (GN) due to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a common cause of crescentic GN. Despite advances in treatment, rates of mortality and progression to end-stage kidney disease remain high. Renal involvement is diagnosed by histological examination of kidney tissue. Serum ANCAs play a significant role in AAV; however, the value of serum ANCA quantification to predict renal involvement is not well-established.

AIM

We aimed to evaluate the diagnostic accuracy of serum ANCA titres in diagnosing AAV with renal involvement.

METHODS

We conducted a retrospective study of consecutive native kidney biopsies reported at our centre from 2016 to 2021. We included all adults who had both a kidney biopsy and ANCA serology. ANCA serology was tested using indirect immunofluorescence with reporting of titres. Antibodies to proteinase 3 and myeloperoxidase were measured using a chemiluminescent immunoassay.

RESULTS

Eight hundred and forty-eight native kidney biopsies were reported during the study period. Five hundred and seven cases were included. The biopsy prevalence of pauci-immune GN in paired samples was 41/507 (8.1%). Most of the cohort had haematuria (66.6%), proteinuria (93.4%) and/or acute kidney injury (65.0%). A positive ANCA at any titre demonstrated a sensitivity of 97.6% and a specificity of 71.2% for a diagnosis of pauci-immune GN. The area under the curve for the receiver operator characteristic was 0.93 (95% confidence interval [CI]: 0.89-0.97). A cutoff ANCA titre of 1:160 provided the optimum balance between a sensitivity of 75.6% (95% CI: 59.7%-87.6%) and a specificity of 94.0% (95% CI: 91.6%-96.0%).

CONCLUSIONS

ANCA titres are highly predictive of pauci-immune GN in the appropriate context. While serum ANCA quantitation may not replace renal biopsy, reporting will assist in the decision to start treatment early for patients with organ or life-threatening disease.

Diagnostic significance of antineutrophil cytoplasmic antibody (ANCA) titres: a retrospective case-control study

OBJECTIVES

To investigate the reliability of elevated titres of antineutrophil cytoplasmic antibody (ANCA) and to identify a cut-off titre in discriminating between ANCA-associated vasculitides (AAV) and its mimickers.

METHODS

This retrospective observational single-centre study included patients over 18 years with positive myeloperoxidase (MPO)-ANCA and/or proteinase 3 (PR3)-ANCA immunoassays over an 8-year period (January 2010 to December 2018), via their electronic medical files. Patients were classified according to the 2022 ACR/EULAR criteria and alternative diagnoses categorised either as non-AAV autoimmune disorders (ANCA-AI) or disorders without autoimmune features (ANCA-O). Findings from the AAV group were compared with those of ANCA-AI and ANCA-O groups and followed by a multivariate logistic stepwise regression analysis of features associated with AAV.

RESULTS

288 ANCA-positive patients of which 49 had AAV were altogether included. There was no difference between patients between the ANCA-AI (n=99) and the ANCA-O (n=140) groups. The AUC for titres discriminating AAV from mimickers was 0.83 (95% CI, 0.79 to 0.87). The best threshold titre, irrespective of PR3-ANCA or MPO-ANCA, was 65 U/mL with a negative predictive value of 0.98 (95% CI, 0.95 to 1.00). On multivariate analysis, an ANCA titre ≥65 U/mL was independently associated with AAV with an OR of 34.21 (95% CI 9.08 to 129.81; p<0.001). Other risk factors were: pulmonary fibrosis (OR, 11.55 (95% CI, 3.87 to 34.47, p<0.001)), typical ear nose and throat involvement (OR, 5.67 (95% CI, 1.64 to 19.67); p=0.006) and proteinuria (OR, 6.56 (95% CI, 2.56 to 16.81; p<0.001)).

CONCLUSION

High PR3/MPO-ANCA titres can help to discriminate between AAV and their mimickers in patients presenting with small-calibre vasculitides, with a threshold titre of 65 U/mL and above.

Relevance of Combined Clinicopathologic Phenotype and Antineutrophil Cytoplasmic Autoantibody Serotype in the Diagnosis of Antineutrophil Cytoplasmic Autoantibody Vasculitis

Introduction

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), 2 major clinicopathologic variants of antineutrophil cytoplasmic autoantibody (ANCA) vasculitides, are mostly associated with proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA, respectively. Less is known regarding the uncommon forms of ANCA vasculitis, PR3-ANCA MPA and MPO-ANCA GPA.

Methods

In this cohort study we detailed the clinical presentation and outcome of patients with PR3-ANCA MPA and MPO-ANCA GPA from the Glomerular Disease Collaborative Network (GDCN) inception cohort. Baseline clinical manifestations, relapses, end-stage kidney disease (ESKD), and survival were compared within MPA cases by PR3-ANCA (n = 116) versus MPO-ANCA (n = 173) and within GPA cases by PR3-ANCA (n = 108) versus MPO-ANCA (n = 43). Fisher's exact test and Wilcoxon two sample test were used for comparisons. Proportional hazards models were used to evaluate the development of relapses, ESKD, and death.

Results

Patients with PR3-ANCA MPA were younger (53 years vs. 62 years, P = 0.0007) and had increased prevalence of joint involvement (56% vs. 40%, P = 0.0115) and ear, nose, and throat (ENT) involvement (44% vs. 26%, P = 0.002) than MPO-ANCA MPA. Relapses, ESKD, and survival were similar between both MPA subsets. Within the GPA group, patients with MPO-ANCA GPA were older (61 years vs. 46 years, P = 0.0007) and more likely female (56% vs. 35%, P = 0.027) than PR3-ANCA GPA patients. MPO-ANCA GPA was also characterized by less prevalent ENT manifestations (58% vs. 77%, P = 0.028) and neurologic manifestations (5% vs. 25%, P = 0.0029), and increased ESKD and mortality.

Conclusions

PR3-ANCA MPA and MPO-ANCA GPA are clinicopathologically distinct subsets of ANCA vasculitis that differ from MPO-ANCA MPA and PR3-ANCA GPA. Although the impact of these differences on the clinical management and outcome warrants further evaluation, these results support the recommendation of including both the phenotypic diagnosis and ANCA serotype in the diagnosis of ANCA vasculitis.

FDG-Avid Tracheal Mass and Cartilage Involvements in ANCA-Negative Granulomatosis With Polyangiitis

ABSTRACT

A 57-year-old woman was referred for progressive dyspnea. CT showed a tracheal mass, suspicious of tracheal neoplasm. The lesion was partially resected, and nonspecific granulation tissue was observed on histology. Her symptoms and CT findings worsened. FDG PET/CT showed increased FDG accumulation in the nasal septum and left eustachian tube in addition to the tracheobronchial lesions. Although the patient was ANCA (antineutrophil cytoplasmic antibodies) negative, a differential diagnosis of granulomatosis with polyangiitis was established and confirmed pathologically. FDG PET/CT was useful for diagnosis of ANCA-negative granulomatosis with polyangiitis, in which tracheobronchial and cartilage lesions were prominent.

Serum ANCA and Overall Mortality: A 10-Year Retrospective Cohort Study on 1,024 Italian Subjects

Background

Antineutrophil cytoplasmic antibodies (ANCA) are primarily involved in the pathogenesis of ANCA-associated vasculitides (AAV). However, ANCA may also be present in healthy subjects and in patients with autoimmune disorders different from AAV. We hypothesized that serum ANCA are associated with a worse prognosis in disorders other than AAV.

Objective

We investigated the association between the overall survival and the presence of serum ANCA in 1,024 Italian subjects with various testing indications in a 10-year interval.

Methods

In this retrospective cohort study, a population of 6,285 patients (many of whom were subsequently excluded due to our criteria) who tested for ANCA at a single center in 10 years was considered, and life status and comorbidities of subjects were collected. We compared the overall survival of ANCA-positive and ANCA-negative patients by means of Kaplan-Meier curves, while a multivariable adjusted Cox regression was used to evaluate the association between the ANCA status and the outcome (death) in terms of hazard ratios (HR) with 95% confidence intervals (CI).

Results

The positivity of perinuclear ANCA (pANCA) increased significantly mortality (HR, 1.60; 95% CI, 1.10–2.32), while cytoplasmic ANCA (cANCA) positivity failed to show a significant association (HR, 1.43; 95% CI, 0.77–2.68). The increased mortality rate was observed for both pANCA and cANCA in patients suffering from rheumatic disorders. No association was found between mortality and anti-MPO (HR, 0.63; 95% CI, 0.20–2.00) or anti-PR3 (HR, 0.98; 95% CI, 0.24–3.96) after adjusting for confounders.

Conclusions

Serum pANCA and cANCA are independent negative prognostic factors in patients with concurrent autoimmune diseases.

Case report of osteolytic lesions in a patient with multisystem granulomatous disease

We present a case of a 70-year-old Caucasian woman with multisystem granulomatous disease involving her lungs, bones and lymph nodes. The patient initially presented with cervical lymphadenopathy and subsequently developed progressive breathlessness. Imaging revealed extensive mediastinal, hilar and intra-abdominal lymphadenopathy as well as bilateral pulmonary parenchymal infiltrates. Lymph node and lung biopsy confirmed non-necrotising granulomatous inflammation while a BAL showed scanty growth of Cryptococcus neoformans and moderate growth of Staphylococcus aureus The patient received intravenous ceftriaxone and had a good response to treatment. She also completed 3 months of oral fluconazole. Although a diagnosis of sarcoidosis was considered most likely, the patient was not initially started on systemic corticosteroids due to concern around possible infection and initial response to antimicrobials. However, her exercise tolerance gradually deteriorated. A craniofacial CT revealed multiple lytic lesions involving the skull and visualised cervical spine. Biopsy of a clivus lesion revealed non-necrotising granulomatous inflammation while fungal cultures and histopathological stains were negative. The patient was diagnosed with widespread sarcoidosis and she was initiated on prednisolone and methotrexate which led to marked clinical and radiological improvement.

Wegener's granulomatosis and differential diagnosis of mucosal leishmaniasis

Granulomatosis with polyangiitis with nasal septal perforation can be confused with infectious diseases such as mucosal leishmaniasis, so these cases warrant an in-depth study in order to provide the correct treatment. Among the main characteristics to consider to define a Wegener's granulomatosis as opposed to an infectious disease are vasculitis, lymphadenopathy, and sinusopathy.

Head and neck manifestations of granulomatosis with polyangiitis

Granulomatosis with polyangiitis is a rare autoimmune condition which causes respiratory tract granulomas, small to medium vessel vasculitis and renal disease. Head and neck manifestations are some of the most common presentations of the condition, with a significant proportion of patients experiencing sinonasal disease alone. The recognition of suggestive imaging findings, in combination with clinical history and serology, aids the diagnosis and appropriate treatment. This pictorial review describes and illustrates the head and neck imaging features of granulomatosis with polyangiitis, highlighting the range of CT and MRI findings of upper aerodigestive tract, orbital and skull-base disease. Recognition of the radiological appearances is of importance, since clinical presentations may be non-specific and limited disease may have negative serology. Imaging features may overlap with other pathologies so important differential diagnoses will be considered, and these are particularly relevant in the context of treatment resistance.

Origin and Expansion of the Serine Protease Repertoire in the Myelomonocyte Lineage

The deepest evolutionary branches of the trypsin/chymotrypsin family of serine proteases are represented by the digestive enzymes of the gastrointestinal tract and the multi-domain proteases of the blood coagulation and complement system. Similar to the very old digestive system, highly diverse cleavage specificities emerged in various cell lineages of the immune defense system during vertebrate evolution. The four neutrophil serine proteases (NSPs) expressed in the myelomonocyte lineage, neutrophil elastase, proteinase 3, cathepsin G, and neutrophil serine protease 4, collectively display a broad repertoire of (S1) specificities. The origin of NSPs can be traced back to a circulating liver-derived trypsin-like protease, the complement factor D ancestor, whose activity is tightly controlled by substrate-induced activation and TNFα-induced locally upregulated protein secretion. However, the present-day descendants are produced and converted to mature enzymes in precursor cells of the bone marrow and are safely sequestered in granules of circulating neutrophils. The potential site and duration of action of these cell-associated serine proteases are tightly controlled by the recruitment and activation of neutrophils, by stimulus-dependent regulated secretion of the granules, and by various soluble inhibitors in plasma, interstitial fluids, and in the inflammatory exudate. An extraordinary dynamic range and acceleration of immediate defense responses have been achieved by exploiting the high structural plasticity of the trypsin fold.

A shared motif of hla-dpb1 affecting the susceptibility to pr3-anca positive granulomatosis with polyangiitis: comparative analysis of a Turkish cohort with matched healthy controls

We aimed to analyse the distribution of HLA Class 2 genotypes which were reported among the genetic risk factors for ANCA-associated vasculitis (AAV) among Turkish patients in comparison with healthy subjects and previously reported data of AAV cohorts. Ninety-eight patients (F/M: 47/51 and mean age: 49 ± 1.14) were enrolled in the study and records of gender and birthplace-matched 196 healthy kidney donors were used as the control group. Patients were classified according to the clinical subgroups and ANCA serotypes (MPO-AAV, PR3-AAV). DNA was isolated from venous blood from all patients, and high-resolution HLA Class 2 genotyping was carried out by using NGS-Omixon Holotype HLA Kit. The frequencies of HLA-DQB1*03:03, - *06:04, and -DPB1*13:01, -*16:01 and -*66:01:00 alleles were significantly higher, and the frequencies of HLA-DQB1*02:02, -DPB1*02:01 and -*04:01 alleles were lower in the PR3-AAV subgroup (n = 53) compared to the controls. Comparison of amino acid sequences of the associated HLA-DPB1 alleles revealed the sequence of D-E-A-V in risk alleles replaced with the G-G-P-M sequence in protective alleles between 84 and 87th positions. Structural analysis of the HLA-DPB1*02:01 showed that this shared position is in the contact area between HLA-DP α and β chains and within pocket 1 of the antigen-binding groove. First HLA genotyping analysis in Turkish AAV patients revealed a negative correlation between PR3-ANCA positivity and certain HLA-DPB1 alleles contradictory to the results reported from European cohorts. Known functional effects of D-E-A-V sequence on HLA-DPB1 support the importance of our finding, but further studies are needed to reveal its pathogenic mechanisms.

The biology, pathogenetic role, clinical implications, and open issues of serum anti-neutrophil cytoplasmic antibodies

Anti-neutrophil cytoplasmic antibodies (ANCA) are a group of autoantibodies, predominantly IgG, involved in the pathogenesis of several autoimmune disorders, detected either through indirect immunofluorescence or enzyme-linked immunosorbent assay. By means of indirect immunofluorescence, the main patterns are C-ANCA (cytoplasmic) and P-ANCA (perinuclear), while proteinase 3 (PR3) and myeloperoxidase (MPO) represent the main autoantigens in granulomatosis with polyangiitis and microscopic polyangiitis, both belonging to the family of ANCA-associated vasculitis (AAV). While several experiments established the pathogenicity of MPO-ANCA, evidence remains elusive for PR3-ANCA and an additional target antigen, i.e. LAMP2, has been postulated with specific clinical relevance. The presence of a subset of AAV without ANCA may be explained by the presence of further target antigens or the presence of molecules in blood which make ANCA undetectable. A rise in ANCA titers is not necessarily predictive of a flare of disease in AAV if not accompanied by clinical manifestations. ANCA may develop through variable mechanisms, such as autoantigen complementarity, apoptosis impairment, neutrophil extracellular traps dysfunction and molecular mimicry. We will provide herein a comprehensive review of the available evidence on the biological mechanisms, pathogenetic role, and clinical implications of ANCA testing and disease management. Further, we will address the remaining open challenges in the field, including the role of ANCA in inflammatory bowel disease and in cocaine-induced vasculitis.

Lesson of the month: Severe granulomatosis with polyangiitis (GPA): a diagnostic challenge during the COVID-19 pandemic

We present the case of a 71-year-old woman with bilateral pneumonia who continued to deteriorate despite multiple courses of antibiotics. When dexamethasone was added to cover the possibility of COVID-19 pneumonia, she rapidly improved. Subsequently, she was found to have a strongly positive PR3 anti-nuclear cytoplasmic antibody (ANCA) and clinical features consistent with granulomatosis with polyangiitis (GPA) with upper respiratory tract and renal involvement. The case highlights how the COVID-19 pandemic can create new challenges in the diagnosis of GPA.

The value of anti-neutrophil cytoplasmic antibodies (ANCA) testing for the diagnosis of ANCA-associated vasculitis, a systematic review and meta-analysis

The testing of anti-neutrophil cytoplasmic antibodies (ANCA) takes an important place in the diagnostic workup to ANCA-associated vasculitis (AAV). Nowadays, it is recommended to screen for the presence of PR3 and MPO specific antibodies first using immunoassay, without the need for ANCA measurement by indirect immunofluorescence (IIF). A literature search was performed to assess the diagnostic test value of ANCA IIF and PR3- and MPO-antibody immunoassay to diagnose AAV. This meta-analysis shows that the c-ANCA testing by IIF has a pooled sensitivity of 75.2% and a pooled specificity of 98.4%. For PR3-antibody immunoassay, the pooled sensitivity depended on the immunoassay method used, and ranged from 79.8% to 86.6%, whereas the pooled specificity ranged from 96.8% to 98.3%. For both p-ANCA IIF and MPO-antibody immunoassay (all methods) sensitivity varied considerably showing pooled values of respectively 46.3% and 58.1%, whereas respective pooled specificity was 91.4% and 95.6%. These findings support the 2017 international consensus that primary anti-PR3 and anti-MPO screening by immunoassay, based on superior immunoassay sensitivity without the need for IIF ANCA testing, improves the diagnostic workup of AAV.

Pulmonary granulomas in a patient with positive ANCA and history of tuberculosis: case report

BACKGROUND

Granulomatous polyangiitis (GPA) is a rare multisystem autoimmune disease of unknown aetiology that is pathologically characterised by necrotising vasculitis, tissue necrosis and granulomatous inflammation, typically in the presence of anti-neutrophil cytoplasmic antibodies (ANCA). However infectious diseases may induce high titre ANCA and mimic vasculitis. Tuberculosis may share many clinical features with GPA including fever, arthralgia, granulomatous inflammation and pulmonary lesions and patients.

CASE PRESENTATION

A 39 year old patient was admitted with ocular irritation and redness, arthralgia and multiple new pulmonary lesions. The past medical history was significant for two episodes of tuberculosis previously requiring prolonged treatment. ANCA antibodies were positive and CT showed multiple pulmonary lesions including cavitatory lesions. After extensive investigation, the patient was treated for GPA with high dose immune suppression with good clinical response.

CONCLUSIONS

Here we review the diagnostic considerations between differentiating GPA and tuberculosis in patients from endemic regions. It is recommended that biopsies of lung lesions, sputum microscopy and multidisciplinary team input are sought as part of the workup when these two differentials are being considered.

Clinical impact of subgrouping ANCA-associated vasculitis according to antibody specificity beyond the clinicopathological classification

OBJECTIVES

In ANCA-associated vasculitis (AAV), classifications have emerged to individualize homogeneous clinical and outcomes patterns, including the recently defined anti-MPO granulomatosis with polyangiitis (GPA) subgroup. This study aimed to retrospectively evaluate the impacts of re-classification based on clinicopathological criteria and/or ANCA specificity.

METHODS

A retrospective monocentric study conducted at Caen University Hospital led to the identification of PR3 or MPO-ANCA AAV patients from January 2000 or September 2011, respectively, to June 2016. Eosinophilic GPA patients were excluded. AAVs were thereby also classified either as GPA or microscopic polyangiitis (MPA) according to the European Medicines Agency vasculitis algorithm.

RESULTS

A total of 150 AAV patients were included (94 GPA, 56 MPA; 87 anti-PR3 and 63 anti-MPO patients). GPA patients exhibited a worse relapse-free survival but a better renal survival (P < 0.001 and P = 0.021, respectively) than MPA patients. Overall, relapse-free and renal survival rates were similar between anti-PR3 and anti-MPO patients (P = 0.35, 0.17 and 0.15, respectively). Similarly, the prognosis was identical between anti-MPO MPA patients and anti-PR3 MPA patients (P = 0.33, 0.19 and 0.65, respectively), and between anti-MPO GPA patients and anti-PR3 GPA patients (P = 0.06, 0.99 and 0.64, respectively). Moreover, anti-PR3 GPA and anti-MPO GPA patients exhibited no differences in clinical manifestations or BVAS score.

CONCLUSION

Clinicopathological classification appeared to be the strongest criterion for distinguishing among homogeneous prognoses of AAV. Individualizing the anti-MPO GPA subgroup does not appear to bring additional value to clinical practice, but multicentre studies are required to confirm this trend.

Relationship of ocular presentation in granulomatosis with polyangiitis to autoantibodies and disease activity

OBJECTIVE

The aim of this study was to assess disease characteristics, autoantibodies, and disease activity in granulomatosis with polyangiitis (GPA) patients with ocular manifestations.

METHODS

The cohort included 46 GPA patients visiting the ophthalmology clinic. Ocular manifestations were recorded, clinical and slit lamp examinations were performed. The Birmingham Vasculitis Activity Score (BVAS) was recorded. Laboratory investigations and the antineutrophil cytoplasmic antibody (ANCA) assay were performed.

RESULTS

Median age of the 22 male and 24 female patients was 44.5 (32-63) years, median disease duration 6.5 (1-16) years. Ocular manifestations were present in all patients: 12 (26.1%) had proptosis; 40 (87%) had scleritis/episcleritis, with perforation in 3 (6.5%); 33 (71.7%) had keratoconjunctivitis (KC), with acute infiltrative stromal keratitis in 11, peripheral ulcerative keratitis in 15, and sclerosing keratitis in 11 patients. Uveitis was present in 11 (23.9%) and retinal changes including vasculitis, exudates, and hemorrhage were present in 7 (15.2%). Blurred vision was present in 43 (93.5%) patients and 2 (4.3%) had vision loss. Glaucoma was present in 4 (8.7%) and hypotony in 2 (4.3%) patients. Involvement was bilateral in 32 (69.6%) patients. Rheumatoid factor (RF) was positive in 56.5% and significantly associated with uveitis (p = 0.04), while antinuclear antibody (ANA) was positive in 45.7% and significantly associated with KC (p = 0.04). BVAS tended to be higher in patients with uveitis (p = 0.49).

CONCLUSION

Ocular involvement must be considered in all GPA patients and referral to an experienced ophthalmologist is mandatory for proper management and improved outcome of such a rare systemic disease. ANA and RF positivity may raise suspicion for KC or uveitis, respectively. There was a remarkable association between uveitis and disease activity.

The Diagnostic and Clinical Utility of Autoantibodies in Systemic Vasculitis

Considerable progress has been made in understanding the role of autoantibodies in systemic vasculitides (SV), and consequently testing for anti-neutrophil cytoplasmic antibodies (ANCA), anti-glomerular basement membrane antibodies (anti-GBM), and anti-C1q antibodies is helpful and necessary in the diagnosis, prognosis, and monitoring of small-vessel vasculitis. ANCA-directed proteinase 3 (PR3-) or myeloperoxidase (MPO-) are sensitive and specific serologic markers for ANCA-associated vasculitides (AAV), anti-GBM antibodies are highly specific for the patients with anti-GBM antibody disease (formerly Goodpasture’s syndrome), and autoantibodies to C1q are characteristic of hypocomlementemic urticarial vasculitis syndrome (HUVS; anti-C1q vasculitis). The results of a current EUVAS study have led to changes in the established strategy for the ANCA testing in small-vessel vasculitis. The revised 2017 international consensus recommendations for ANCA detection support the primary use PR3- and MPO-ANCA immunoassays without the categorical need for additional indirect immunofluorescence (IIF). Interestingly, the presence of PR3- and MPO-ANCA have led to the differentiation of distinct disease phenotype of AAV: PR3-ANCA-associated vasculitis (PR3-AAV), MPO-ANCA-associated vasculitis (MPO-AAV), and ANCA-negative vasculitis. Further studies on the role of these autoantibodies are required to better categorize and manage appropriately the patients with small-vessel vasculitis and to develop more targeted therapy.

Gastrointestinal and Hepatic Disease in Vasculitis

Vasculitis is an inflammatory condition that targets the blood vessels, which may occur in isolation or as a component of a systemic inflammatory condition. Although many of the vasculitides can directly affect the organs of the gastrointestinal system, some types exhibit a proclivity for certain gastrointestinal and hepatic organs. Often a patient presents with nonspecific symptoms, delaying the diagnosis and treatment of the underlying vasculitis. Vasculitis can also present with severe manifestations, such as upper gastrointestinal bleeds and bowel perforation. It is important to identify the signs and symptoms of vasculitis in gastrointestinal system and institute appropriate treatment.

Granulomatosis with polyangiitis: a 17 year experience from a tertiary care hospital in Pakistan

Objective

Granulomatosis with Polyangiitis (GPA) is an autoimmune, multi-system, small and medium vessel vasculitis with granulomatous inflammation. Aim of this study was to assess the clinical and radiological presentations of patients with GPA amongst the Pakistani population. It is a single centre retrospective single observation study.

Results

Study was conducted at the Aga Khan University Hospital, Karachi with records were reviewed from January 2000 to December 2017. Definitive diagnosis was made using a combination of serological anti-neutrophil cytoplasmic antibody (ANCA) testing along with the clinical and radiological presentation. A total of 51 patients met the diagnostic criteria in the time frame of the study. There were 23 males and 28 females with mean age of 44.0 ± 17.8 years on presentation. Arthritis was the most common symptom present in 41.2% of the cases followed by cough in 32.0%. Sixteen patients showed pulmonary infiltrates on chest X-ray. C-ANCA was positive in all of the patients compared with 21.6% p-ANCA positivity. A total of 13 biopsies were done. The median Birmingham Vasculitis Activity Score was 12. We report a 17.6% mortality rate with 5 deaths occurring due to respiratory failure. GPA is a diagnostic challenge leading to late diagnosis which can contribute to significant morbidity and mortality specially in the Third World.

New concepts in ANCA detection and disease classification in small vessel vasculitis: the role of ANCA antigen specificity

Anti-neutrophil cytoplasmic antibodies (ANCA) play a central role in the diagnosis and pathogenesis of patients with ANCA-associated vasculitis. ANCA-associated vasculitis is a rare disease characterized by necrotizing inflammation of small/medium-sized blood vessels with and without granuloma in different organs. The main syndromes are granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic GPA. ANCA in these diseases are almost always directed against proteinase 3 and myeloperoxidase. Most laboratories worldwide use as standard the indirect immunofluorescence technique to screen for ANCA and then confirm positive IFT results with antigen specific immunoassyas for PR3- and MPO-ANCA. New guidelines for ANCA testing have been developed based on a recent European multicentre study, and according to the revised 2017 international consensus recommendations, testing for ANCA in small vessel vasculitis can be done by PR3- and MPO-ANCA immunoassays, without the categorical need for IIF. The new testing strategy for ANCA in vasculitis directly identifies the ANCA target antigen and has a particular value for the AAV sub-classification. Recent studies have shown that AAV can be classified based on ANCA serotype. ANCA presence and the antigen specificity also may have important value as a prognostic factor and may serve as a guide for immunosuppressive therapy. The clinical utility of ANCA depends on the type of assay performed and the appropiate ordering of testing the right clinical setting. Accurate identification of all patients with AAV and the avoidance of misdiagnosis can be achieved using a "gating policy" based on clinical information given to the laboratory at the time of request.

Anti-neutrophil cytoplasm antibodies (ANCA): Recent methodological advances-Lead to new consensus recommendations for ANCA detection

The current practice for detection of anti-neutrophil cytoplasm antibodies (ANCA) directed against proteinase 3 (PR3) and myeloperoxidase (MPO) has been screening by indirect immunofluorescence (IIF) followed by an antigen specific tests for PR3- and MPO-ANCA. However, ANCA diagnostics have undergone many technical developments that have affected the 1999 international consensus recommendations, and lead to a revision of the existing ANCA detection strategy. Recent European multicentre studies have compared the diagnostic performance of various ANCA detection methods and demonstrated that PR3- and MPO-ANCA immunoassays yielded the highest diagnostic accuracy. New guidelines for ANCA testing have been developed based on these data. According to the revised 2017 international consensus recommendations, testing for ANCA in small vessel vasculitis can be done by PR3- and MPO-ANCA immunoassays, without the categorical need for IIF. Thus, IIF can be discarded completely, or can be used as confirmation assays instead a screening test. Clearly, though, the new testing strategy for ANCA in vasculitis must identify the ANCA target antigen, as PR3- and MPO-ANCA serotype correlate well with disease expression. Furthermore, recent studies have shown that AAV can be classified based on ANCA serotype, since PR3- and MPO-ANCA- diseases are strongly associated with distinguishable genetic alleles, different clinical and histological features. ANCA presence and the antigen specificity also may have important value as a prognostic factor and may serve as a guide for immunosuppressive therapy. In the current review, we summarize the novelties in ANCA testing, present the 2017 revised international consensus on ANCA testing in vasculitis, evaluate the diagnostic significance of ANCA, and discuss the role of ANCA serotypes in the diagnostic work-up of patients with AAV.

Position paper: Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangiitis and microscopic polyangiitis

Anti-neutrophil cytoplasmic antibodies (ANCAs) are valuable laboratory markers used for the diagnosis of well-defined types of small-vessel vasculitis, including granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). According to the 1999 international consensus on ANCA testing, indirect immunofluorescence (IIF) should be used to screen for ANCAs, and samples containing ANCAs should then be tested by immunoassays for proteinase 3 (PR3)-ANCAs and myeloperoxidase (MPO)-ANCAs. The distinction between PR3-ANCAs and MPO-ANCAs has important clinical and pathogenic implications. As dependable immunoassays for PR3-ANCAs and MPO-ANCAs have become broadly available, there is increasing international agreement that high-quality immunoassays are the preferred screening method for the diagnosis of ANCA-associated vasculitis. The present Consensus Statement proposes that high-quality immunoassays can be used as the primary screening method for patients suspected of having the ANCA-associated vaculitides GPA and MPA without the categorical need for IIF, and presents and discusses evidence to support this recommendation.

Myeloperoxidase-Antineutrophil Cytoplasmic Antibody (ANCA)-Positive and ANCA-Negative Patients With Granulomatosis With Polyangiitis (Wegener's): Distinct Patient Subsets

OBJECTIVE

To examine the relationship of antineutrophil cytoplasmic antibody (ANCA) type and ANCA-associated vasculitis (AAV) diagnosis with demographic features, disease manifestations, and clinical outcomes. We focused on patients who account for the differences between ANCA type and disease type classifications: anti-myeloperoxidase (MPO)-ANCA-positive and ANCA-negative patients with granulomatosis with polyangiitis (Wegener's) (GPA).

METHODS

We performed a pooled analysis of the Wegener's Granulomatosis Etanercept Trial and the Rituximab in ANCA-Associated Vasculitis trial comparing patients with MPO-ANCA-positive GPA and patients with ANCA-negative GPA to patients with proteinase 3 (PR3)-ANCA-positive GPA and patients with MPO-ANCA-positive microscopic polyangiitis (MPA).

RESULTS

Of the 365 patients analyzed, 273 (75%) had PR3-ANCA-positive GPA, 33 (9%) had MPO-ANCA-positive GPA, 15 (4%) had ANCA-negative GPA, and 44 (12%) had MPO-ANCA-positive MPA. MPO-ANCA-positive GPA patients were younger at diagnosis compared to MPO-ANCA-positive MPA patients (53 versus 61 years; P = 0.02). Their disease manifestations and rates of relapse were similar to those of PR3-ANCA-positive GPA patients. Relapse was more frequent in MPO-ANCA-positive GPA patients than in patients with MPO-ANCA-positive MPA at trial entry as well as at 12 and 18 months. ANCA-negative patients with GPA had lower Birmingham Vasculitis Activity Score for Wegener's Granulomatosis scores at trial entry than PR3-ANCA-positive patients with GPA (4.5 versus 7.7; P < 0.01), primarily because of a lower prevalence of renal involvement.

CONCLUSION

We were unable to demonstrate important clinical differences between MPO-ANCA-positive and PR3-ANCA-positive patients with GPA. The risk of relapse was associated more closely with disease type than with ANCA type in this patient cohort. These findings deserve consideration in the assessment of relapse risk in patients with AAV.

Discrepancies between two immunoassays for the determination of MPO and PR3 autoantibodies

BACKGROUND

Testing for autoantibodies to myeloperoxidase (MPO) and proteinase 3 (PR3) is part of anti-neutrophil cytoplasmic antibodies (ANCA) test that aids the diagnosis of a number of autoimmune diseases including small-vessel vasculitis. We characterized the differences between two automated immunoassays at three facilities for measuring MPO- and PR3-ANCA autoantibodies.

METHODS

117 serum samples were analyzed for MPO and PR3 autoantibodies. The INOVA QUANTA Lite® IgG assay (INOVA Diagnostics) were performed at two facilities and the Bio-Plex® 2200 Vasculitis Panel (Bio-Rad) were performed at a third reference lab. The results were compared both qualitatively (between INOVA QUANTA Lite® and Bio-Plex® methods) and quantitatively (between two sites performing INOVA QUANTA Lite® assays).

RESULTS

Comparison of the INOVA QUNATA Lite® assays at two different facilities (n=36) demonstrated high concordance (97.2% for MPO and 94.4% for PR3) and quantitative correlation (R²=0.973 for MPO and R²=0.935 for PR3). Conversely, INOVA QUNATA Lite® and Bio-Plex® methods showed poor concordance at 70.4% for MPO (n=81; 95% CI: 59.7% to 79.2%) and at 76.5% for PR3 (n=81; 95% CI: 66.2% to 84.4%).

CONCLUSION

This study demonstrated low concordance between two methods for MPO-ANCA and PR3-ANCA measurements. Given the discrepancies, the performance of different autoantibody immunoassay methods should be taken into consideration when evaluating MPO-ANCA and PR3-ANCA results.

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.

Simultaneous comprehensive multiplex autoantibody analysis for rapidly progressive glomerulonephritis

Rapidly progressive glomerulonephritis (RPGN) is mainly caused by anti-glomerular basement membrane (GBM) antibody-mediated glomerulonephritis, immune-complex or anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides and leads to rapid loss of renal function. Detection of ANCA and autoantibodies (autoAbs) to GBM and dsDNA enables early diagnosis and appropriate treatment of RPGN aiding in preventing end-stage renal disease.Determination of ANCA on neutrophils (ANCA) as well as autoAbs to myeloperoxidase (MPO-ANCA), proteinase 3 (PR3-ANCA), GBM, and dsDNA was performed by the novel multiplex CytoBead technology combining cell- and microbead-based autoAb analyses by automated indirect immunofluorescence (IIF). Forty patients with granulomatosis with polyangiitis (GPA), 48 with microscopic polyangiitis (MPA), 2 with eosinophilic GPA, 42 with systemic lupus erythematosus (SLE), 43 with Goodpasture syndrome (GPS), 57 with infectious diseases (INF), and 55 healthy subjects (HS) were analyzed and findings compared with classical single testing.The CytoBead assay revealed for GPA, MPA, GPS, and SLE the following diagnostic sensitivities and for HS and INF the corresponding specificities: PR3-ANCA, 85.0% and 100.0%; MPO-ANCA, 77.1% and 99.1%; anti-GBM autoAb, 88.4% and 96.4%; anti-dsDNA autoAb, 83.3% and 97.3%; ANCA, 91.1% and 99.1%, respectively. Agreement with classical enzyme-linked immunosorbent assay and IIF was very good for anti-GBM autoAb, MPO-ANCA, PR3-ANCA, and ANCA, respectively. Anti-dsDNA autoAb comparative analysis demonstrated fair agreement only and a significant difference (P = 0.0001).The CytoBead technology provides a unique multiplex reaction environment for simultaneous RPGN-specific autoAb testing. CytoBead RPGN assay is a promising alternative to time-consuming single parameter analysis and, thus, is well suited for emergency situations.

Snorting the clivus away: an extreme case of cocaine-induced midline destructive lesion

Cocaine is a drug with relevant socioeconomic and clinical implications, which is usually recreationally used for its stimulant effects. It is widely known that the habit of snorting cocaine is associated with a peculiar type of drug-induced chronic rhinitis, which leads to inflammation of the sinonasal mucosa, slowly progressing to a destruction of nasal, palatal and pharyngeal tissues. These characteristic lesions due to cocaine abuse are commonly called cocaine-induced midline destructive lesions (CIMDL). Diagnosis is not always straightforward, since various conditions, mainly vasculitis, might mimic this acquired condition. The extent of pharyngeal involvement varies, although often a prolonged abuse can trigger a progressive destruction of oral and nasal tissues, with development of infections and recurrent inflammation. Our article focuses on cocaine as a world health problem with important ear, nose and throat implications and discusses the difficulties in diagnosing and treating CIMDL, through a case report.

High PR3-ANCA positivity in a patient with chronic inflammatory demyelinating polyneuropathy

Proteinase 3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) is reported to be highly specific to vasculitis compared to myeloperoxidase (MPO)-ANCA. We report a case of a 19-year-old woman with chronic inflammatory demyelinating polyneuropathy (CIDP) with high PR3-ANCA positivity. The patient responded well to intravenous immunoglobulin plus oral steroid, and showed no signs of systemic vasculitis during the subsequent 10 months of follow-up. Our present case suggests that CIDP may accompany high PR3-ANCA levels, which should be differentiated from axonal neuropathy due to vasculitis.

Small vessel vasculitis of the lung

Interstitial Lung Disease Program, National Jewish Medical and Research Center, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA The diagnosis and management of SVV remains one of the most challenging clinical scenarios encountered by a clinician. Careful attention to detail and a thorough knowledge of the specific disorders, their therapies, and complications thereof is required to optimally care for these patients. The recent completion of a number of randomized, controlled, multicenter clinical trials has greatly improved our knowledge base and ability to care for vasculitis patient. The next decade holds even more promise.

Granulomatosis with polyangiitis (Wegener's disease): An updated review of ocular disease manifestations

Granulomatosis with polyangiitis (GPA) is a potentially lethal systemic disorder that is characterized by necrotizing vasculitis of small arteries and veins. The respiratory system is most commonly affected in limited forms of the disease, however upper and lower respiratory system, systemic vasculitis, and necrotizing glomerulonephritis are the characteristic components of the disease triad. The peak incidence is observed at 64-75 years of age, with a prevalence of 8-10 per million depending on geographic location. In this review we focus on the ocular manifestations of the disease which occur in nearly in one third of the patients. In addition we describe the neuro-ophthalmic complications which occur in up to half of cases. We also discuss the current systemic treatment options including corticosteroids, cyclophosphamide, azathioprine, and the available biologic response modifiers including rituximab. The disease remains difficult to diagnose due to the generalized symptomatic presentation of patients with GPA. As a result, several sets of diagnostic criteria have been developed which include clinical, serological, and histopathological findings to varying extents. Early diagnosis and multi-specialty collaboration among physicians is necessary to adequately manage the disease and the potential complications that may result from drugs used in the treatment of the disease. Despite recent advances, more research is necessary to prevent the high rates of mortality from the disease itself and from therapeutic side effects.

A diagnostic pitfall in IgG4-related hypophysitis: infiltration of IgG4-positive cells in the pituitary of granulomatosis with polyangiitis

INTRODUCTION

Immunoglobulin (Ig) G4-related hypophysitis is an emerging clinical entity, which is characterized by an elevated serum IgG4 concentration and infiltration of IgG4-positive plasma cells in the pituitary. Although some criteria for its diagnosis have been proposed, they have not been fully established. In particular, differential diagnosis from secondary chronic inflammation including granulomatosis with polyangiitis (GPA) is difficult in some cases. We describe central diabetes insipidus with pituitary swelling exhibiting infiltration of IgG4-positive cells.

PATIENT

A 43-year-old woman in the remission stage of GPA presented with sudden-onset polyuria and polydipsia. Pituitary magnetic resonance imaging revealed swelling of the anterior and posterior pituitary and stalk, with heterogeneous gadolinium enhancement and disappearance of the high signal intensity of the posterior pituitary. Evaluation of biochemical markers for GPA suggested that the disease activity was well-controlled. Endocrinological examination revealed the presence of central diabetes insipidus and growth hormone deficiency. Pituitary biopsy specimen showed IgG4-positive cells, with a 43% IgG4(+)/IgG(+) ratio, which met the criteria for IgG4-related hypophysitis. However, substantial infiltration of polymorphonuclear neutrophils with giant cells was also noted, resulting in a final diagnosis of pituitary involvement of GPA.

CONCLUSION

These results suggest that pituitary involvement of GPA should be taken into account for the differential diagnosis of IgG4-related hypophysitis.

Granulomatosis with polyangiitis presenting as a choroidal tumor

Granulomatosis with polyangiitis (GPA) sometimes involves the eye orbit; however, choroidal involvements in GPA had been rarely reported. We report a rare case presenting with a choroidal mass in an 83-year-old Japanese woman who presented with left eye pain. Diagnostic biopsy revealed necrotizing vasculitis with infiltrates of inflammatory cells. Diagnosis was localized granulomatosis with polyangiitis. Combined treatments with corticosteroid plus azathioprine resolved the choroidal mass region. Although treatment with corticosteroid and immunosuppressive agents improves the prognosis of the disease, ocular morbidity is still well recognized. Clinicians should consider a differential diagnosis of GPA in patients with inflammatory choroidal tumors.

Diagnosis and therapeutic options for peripheral vasculitic neuropathy

Vasculitis can affect the peripheral nervous system alone (nonsystemic vasculitic neuropathy) or can be a part of primary or secondary systemic vasculitis. In cases of pre-existing systemic vasculitis, the diagnosis can easily be made, whereas suspected vasculitic neuropathy as initial or only manifestation of vasculitis requires careful clinical, neurophysiological, laboratory and histopathological workout. The typical clinical syndrome is mononeuropathia multiplex or asymmetric neuropathy, but distal-symmetric neuropathy can frequently be seen. Standard treatments include steroids, azathioprine, methotrexate and cyclophosphamide. More recently the B-cell antibody rituximab and intravenous immunoglobulins have shown to be effective in some vasculitic neuropathy types.

Pathogenesis of anti-neutrophil cytoplasmic antibody-associated vasculitis: challenges and solutions 2014

Anti-neutrophil cytoplasmic autoantibodies (ANCA) with specificity for proteinase 3 (PR3-ANCA) or myeloperoxidase (MPO-ANCA) are a defining feature of ANCA-associated vasculitides (AAV). They play a pivotal role in disease pathophysiology and have strongly improved early diagnosis and treatment of these infrequent, but potentially fatal diseases. Neutrophils and their products are major players in initiating the autoimmune response and tissue destruction in vasculitic as well as granulomatous inflammation. This review highlights recent findings on old and novel players (ANCA, neutrophils, neutrophil extracellular traps, fibroblasts, immune cells and complement) and puts them into context with the current understanding of disease mechanisms in AAV.

18F-FDG PET/CT findings preceded elevation of serum proteinase 3 antineutrophil cytoplasmic antibodies in Wegener granulomatosis

A 67-year-old woman underwent F-FDG PET/CT after developing a fever of unknown origin. PET/CT revealed intensive FDG uptake at the nasal and lung lesions. On the laboratory data, serum myeloperoxidase antineutrophil cytoplasmic antibodies (ANCA) titer was elevated, although serum directed against proteinase 3 (PR3) ANCA titer was within normal limits. One month after treatment, follow-up PET/CT revealed decreased FDG uptake at the lesions. One year later, serum PR3-ANCA titer elevated, which finally led to a diagnosis of Wegener granulomatosis (WG). WG lesions may be detected earlier by FDG PET/CT than by serum PR3-ANCA titers.

Characteristics of granulomatosis with polyangiitis patients in Japan

OBJECTIVES

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a disease with significant ethnic differences. Reports on characteristics of Japanese granulomatosis with polyangiitis (GPA) patients are limited, and this study was undertaken to determine the characteristics of Japanese GPA patients.

METHODS

This was a retrospective chart study of 24 Japanese GPA patients. GPA was defined according to the European Medicines Agency algorithm.

RESULTS

The percentage of MPO-ANCA-positive patients was 33.3%, higher than the percentages reported in studies from Western countries. MPO-ANCA-positive GPA patients differed from PR3-ANCA-positive GPA patients in organs involved at diagnosis with MPO-ANCA-positive patients having nose and sinus involvement less frequently compared to PR3-ANCA-positive patients. Interstitial lung infiltrates were more common among MPO-ANCA-positive GPA patients compared to PR3-ANCA-positive GPA patients.

CONCLUSION

Among Japanese GPA patients, the proportion of MPO-ANCA-positive patients is higher compared to reports from Western countries, and those patients are often different from the classical picture of GPA.

Current and emerging techniques for ANCA detection in vasculitis

Detection of antineutrophil cytoplasmic antibodies (ANCAs) is a well-established diagnostic test used to evaluate suspected necrotizing vasculitis of small blood vessels. Conditions associated with these antibodies, collectively referred to as ANCA-associated vasculitides, include granulomatosis with polyangiitis (formerly known as Wegener granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (formerly known as Churg-Strauss syndrome). The diagnostic utility of ANCA testing depends on the type of assay performed and on the clinical setting. Most laboratories worldwide use standard indirect immunofluorescence tests (IFT) to screen for ANCA and then confirm positive IFT results with antigen-specific tests for proteinase 3 (PR3) and myeloperoxidase (MPO). Developments such as automated image analysis of immunofluorescence patterns, so-called third-generation PR3-ANCA and MPO-ANCA ELISA, and multiplex technology have improved the detection of ANCAs. However, challenges in routine clinical practice remain, including methodological aspects of IFT performance, the diverse antigen-specific assays available, the diagnostic value of testing in clinical settings and the prognostic value of serial ANCA monitoring in the prediction of disease relapse. This Review summarizes the available data on ANCA testing, discusses the usefulness of the various ANCA assays and advises on the clinical indications for the use of ANCA testing.

A population-based study showing better renal prognosis for proteinase 3 antineutrophil cytoplasmic antibody (ANCA)-associated nephritis versus myeloperoxidase ANCA-associated nephritis

OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is usually differentiated based on clinical phenotypes, but recent data indicate that myeloperoxidase (MPO)-AAV is genetically distinct from proteinase 3 (PR3)-AAV. We reviewed a population-based cohort of AAV, focusing on differences in clinical and laboratory characteristics and to compare renal outcome between MPO-ANCA and PR3-ANCA nephritis.

METHODS

All new cases of AAV diagnosed between 1997 and 2009 in a geographically defined area in southern Sweden were retrieved using a validated search algorithm. Data were collected from time of diagnosis and end of followup. Renal and patient survival were analyzed according to ANCA serotype.

RESULTS

During the study period, 201 patients were diagnosed with AAV, 98 tested positive for PR3-ANCA, and 85 for MPO-ANCA. Patients with PR3-ANCA were younger, had significantly higher inflammatory activity, and had a larger number of organs involved at diagnosis, but nephritis was more prevalent among patients with MPO-associated (72/85; 85%) versus PR3-associated disease (67/98, 68%). When comparing only patients with ANCA-associated nephritis, those with MPO-ANCA were more likely to develop endstage renal disease (n = 27, 38%) than those with PR3-ANCA (n = 10, 15%), p = 0.003. The risk remained significantly elevated after adjusting for sex, age, and s-creatinine level at diagnosis (HR 2.64; 95% CI 1.25-5.58; p = 0.003). There were no significant differences in mortality rates between the 2 groups.

CONCLUSION

The outcome in this population-based cohort indicates that among AAV patients with nephritis, renal prognosis is better in the PR3-ANCA group, even after adjustment for sex, age, and renal function at diagnosis.

A novel autoantibody against moesin in the serum of patients with MPO-ANCA-associated vasculitis

BACKGROUND

Antineutrophil cytoplasmic autoantibody (ANCA) directed against myeloperoxidase (MPO), a diagnostic criterion in MPO-ANCA-associated vasculitis (MPO-AAV), does not always correlate with disease activity. Here, we detected autoantibodies against moesin, which was located on the surface of stimulated endothelial cells, in the serum of patients.

METHODS

The anti-moesin autoantibody titer was evaluated by ELISA. Seventeen kinds of cytokines/chemokines were measured by a Bio-Plex system.

RESULTS

Serum creatinine in the anti-moesin autoantibody-positive group was higher than that in the negative group. Additionally, interferon (IFN)-γ, macrophage chemotactic peptide-1 (MCP-1), interleukin (IL)-2, IL-7, IL-12p70, IL-13, granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor were significantly higher in the positive group. Furthermore, IL-7 and IL-12p70 levels correlated with the anti-moesin autoantibody titer. Based on these findings and the binding of anti-moesin IgG to neutrophils and monocytes, we detected the secretion of cytokines/chemokines such as IFN-γ, MCP-1 and GM-CSF from these cells.

CONCLUSIONS

The anti-moesin autoantibody existed in the serum of patients with MPO-AAV and was associated with the production of inflammatory cytokines/chemokines targeting neutrophils with a cytoplasmic profile, which suggests that the anti-moesin autoantibody has the possibility to be a novel autoantibody developing vasculitis via neutrophil and endothelial cell activation.

A case of granulomatosis with polyangiitis (Wegener's granulomatosis) presenting with marked inflamed tracheobronchial mucosa

A 70-year-old man was admitted to our hospital because of weight loss and persistent dry cough. Chest radiograph and CT showed multiple infiltrates in the bilateral upper lobes and the remarkably thickened bronchial walls. Bronchoscopy revealed diffuse erythema and edema of the tracheobronchial mucosa without any ulcerous legions. Serum MPO-ANCA was positive (155 EU). Transbronchial biopsy was performed and revealed necrotic granulomas with multinucleated giant cells in the bronchial/bronchiolar and parenchymal lesions. Thus, we diagnosed it as a localized form of granulomatosis with polyangiitis (GPA, Wegener's granulomatosis). After treatment with corticosteroid and cyclophosphamide, the bronchial findings were entirely resolved. We report here a rare case of GPA presenting with markedly inflamed tracheobronchial mucosa.