Positive ANCA Research Articles

HRCT imaging of pulmonary involvement in granulomatosis with polyangiitis and microscopic polyangiitis at disease onset and during follow-up

BackgroundThe pulmonary involvement in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) is well known at disease onset but data during follow-up (after the induction regimen and when the first relapse occurs) are limited. Our goal was to analyze chest high-resolution computed tomography (HRCT) findings of (ANCA)-associated vasculitis patients. MethodAll consecutive unselected AAV patients over eighteen with positive ANCA status and with HRCT chest performed at the diagnosis were retrospectively enrolled between 2004 and 2019 at the Toulouse University Hospital (France). Two experienced pulmonologists and one expert respiratory radiologist reviewed independently HRCT chest scans. ResultsA total of 157 AAV patients were included in the study. Two-thirds of AAV patients had pulmonary involvement at diagnosis. Diffuse alveolar hemorrhage (DAH) was observed in 31.2 % of cases, nodules and masses in 18.5 %, bronchial airway involvement in 13.4 %, and interstitial involvement in 12.7 %. Following the induction regimen, chest HRCT scans over a two-year period demonstrated significant improvement in DAH and nodular manifestations, whereas bronchial airway involvement exhibited variability and half of cases of interstitial lung disease (ILD) had progressive course. Outcomes and survival rates are better for nodular and bronchial involvement. DAH was the most frequent cause of deaths. Progressive fibrotic changes in ILD over time could impact prognosis despite AAV remission. ConclusionEmploying a pattern-based approach with HRCT chest scans to assess lung involvement could be valuable in predicting treatment response, relapse, mortality, and could improved the management of AAV patients.

Bacterial Endocarditis with Strongly Positive Anti-PR3 ANCA

Bacterial Endocarditis with Strongly Positive Anti-PR3 ANCA

ANCA positivity and the limited expression of vasculitides.

ANCA positivity and the limited expression of vasculitides.

Small fiber neuropathy associated with ANCA positivity: a case series and brief literature review.

Small fiber neuropathy [SFN] is a common peripheral neurologic disorder with a vast array of implicated etiologies. It has previously been proposed that some forms of immune-mediated small fiber neuropathy are driven by vasculitis, though antinuclear cytoplasmic antibodies [ANCA] antibodies have not commonly been reported in association with SFN, thus far. We present this case series to discuss the observation of a possible novel association between ANCA and SFN. This is a retrospective case series of 6 patients with SFN and ANCA positivity, with and without systemic manifestations. Patients included were diagnosed with SFN by skin biopsy or autonomic function testing and were seropositive for ANCA by ELISA. Six patients are outlined, including 4 females and 2 males. Antigen specific antibodies were MPO alone in 4 cases, PR3 alone in 1 case and both MPO and PR3 in 1 case. Systemic vasculitis was noted in 2 patients. Five patients received immunosuppression. Three patients experienced partial improvement, while symptoms stabilized in 3 patients. This is the first series of patients with suspected immune-mediated SFN and ANCA antibody positivity, raising the possibility of ANCA mediated isolated SFN. This is in contradistinction to the more typical ANCA-mediated peripheral neuropathy manifestations of mononeuropathy multiplex or axonal sensorimotor neuropathy. We cannot unequivocally prove ANCA-associated vasculitis [AAV] causality in these cases; however, the stabilization in SFN symptomatology and associated improvement in ANCA antibody titer, after AAV treatment, may be indicative of an association.

Intravenous immunoglobulin therapy in antineutrophil cytoplasmic antibody-associated vasculitis

IntroductionAnti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) includes three heterogeneous and difficult to treat clinical entities. Intravenous immunoglobulins (IVIG) may constitute a good therapeutic option, although data hitherto are scarce. The aim of this study was to assess the effectiveness and safety of IVIG in AAV in a real-world setting. MethodsSingle center observational study of patients with AAV with at least one cycle of IVIG since January of 2000 to December of 2020. AAV diagnosis was based on a compatible clinical presentation and positive ANCA serology and/or compatible histology. Disease activity was assessed by the Birmingham Vasculitis Activity Score (BVAS). The effectiveness was evaluated by clinical and laboratory parameters (CRP, ESR) and its glucocorticoid-sparing effect. These variables were measured at one, six, twelve and twenty-four months of IVIG treatment. The doses of IVIG were 2g/kg in the following cycles of administration: 1 g/kg/day in 2 days (n=12); 0.5 g/kg/day in 4 days (n=11); 0.4 g/kg/day in 5 days (n=5). The clinical improvement was classified according to BVAS categories in remission, partial response and no response. ResultsTwenty-eight patients (15 granulomatosis-polyangiitis, 10 microscopic polyangiitis and 3 eosinophilic granulomatosis with polyangiitis) were included. Reasons for using IVIG were relapse/refractory disease (n=25), active or suspected infection (n=3), and both (n=5). We observed a rapid and maintained BVAS score improvement, increasing from 34.6% at 1 month to 56.5% at 2 years of follow-up (p=0.12), and a reduction of glucocorticoids dose. Therapy was well tolerated and adverse events mild and scarce. ConclusionIVIG represents an effective and relative safe therapeutic alternative in relapsing/refractory AAV or in presence of a concomitant active infection.

#6895 ANCA AND IGA NEPHROPATHY: ASSOCIATION OR PROGNOSTIC FACTOR

Abstract Background and Aims ImmunoglobulinA(IgA) nephropathy (IgAN), the most prevalent form of primary glomerulonephritis worldwide, is characterized by mesangial cell proliferation, matrix expansion, and mainly mesangial IgA deposition, often in conjunction with C3 and IgG and/or IgM. Its pathogenisis is enigmatic, It is reported that approximately 35-42% of IgAN patients have a history of macrohematuria before kidney biopsy. Its a benign pathology which somtimes could be associated with cresentic proliferation and more rarely by the presence of ANCA antibodies. Method We retrospectively analyzed the epidemiologic, clinical and histological data of 27 patients with Ig A nephropathy proven by biopsy and we compared 2 groups ANCA positive and ANCA negative patients. Results The present study involved 27 patients, 18 men and 9 women, the average age was 27.9 years 3 patients were ANCA positive compared to 24 ANCA negative ; (2 were MPO-ANCA and 1 PR3-ANCA). ANCA positive patients were older, with more severe initial renal function, lower hemoglobin, and a higher percentage of general symptoms than the ANCA negative ones Histologically, therewas a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients ANCA-positive patients with IgA nephropathy had a higher percentage of crescentic glomeruli (54.5%) compared with ANCA-negative patients with crescentic IgA nephropathy (26%). The ANCA positive patients was all treated by solumedrol boli and oral corticotherapy and showed more severe prognosis, the 3 patients progressed to ESKD. 4 ANCA-negative patients were treated with oral corticotherapy, some from the other 20 patients have been put on renin angiotensin system bloquers treatment and thy shoxed a better renal prognosis. Conclusion IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and lower renal prognosis. The ANCA antibodies should be screened in patients with severe forms of IgAN.

#3486 CELL-FREE CIRCULATING DNA IN ANCA-ASSOCIATED VASCULITIS – A COMPARISON OF PATIENTS DURING ACTIVE DISEASE AND REMISSION

Abstract Background and Aims Patients with ANCA-associated vasculitis (AAV) undergo immunosuppressive treatment to thwart organ failure and avoid relapse. However, the treatment is associated with risk of infections and malignancy. There are currently no reliable biomarkers which can be used in the clinic to assess disease activity. Neutrophil extracellular traps containing nuclear (n) and/or mitochondrial (mt) DNA have been implied in the pathogenesis of AAV. The aim of this study was to explore whether there is a difference in levels of circulating cell-free DNA (cfDNA) amongst AAV patients during active disease and in remission. Method Paired samples from 7 male and 9 female patients with AAV, of which 10 were diagnosed with GPA, were obtained during both active disease and clinical remission as part of an ongoing observational prospective study. Participants’ ages ranged from 21.8 to 80.0 years (median = 64.9), and 11 participants had a history of kidney engagement. After DNA-extraction digital droplet PCR was performed to obtain levels of mtDNA and nDNA. Clinical diagnosis (GPA or MPA), ANCA-positivity, kidney involvement, and Birmingham vasculitis activity score (BVAS) were also assessed. Results There were no significant differences in levels of mtDNA or nDNA in patients with active disease compared to remission; mtDNA (median = 14 520 and 11 985 copies/µL respectively, p = .379) and nDNA (median = 4.45 and 4.70 copies/µL, p = .569). The ratio between mtDNA and nDNA did not differ either (median 2100 and 2400, p = .679). A strong correlation between mtDNA- and nDNA levels (r = .920, p < .001) was found, whereas no correlations were found between cfDNA and age, sex, clinical phenotype, ANCA positivity, kidney engagement or BVAS (Tables 1 and 2). Conclusion This study provides additional information regarding levels of mtDNA and nDNA comparing AAV patients during active disease and in clinical remission. The lack of association with disease activity and the correlation between nDNA and mtDNA may indicate cell damage as a source of cfDNA. To further delineate the contribution of NETs to the levels of cfDNA, and the mechanisms behind cellular injury and inflammation, studies with larger samples with longitudinal follow-up and healthy controls are needed.

#5132 POST-COVID-19 ANTI-GLOMERULAR BASEMENT MEMBRANE DISEASE: TWO CLINICAL CASES

Abstract Background and Aims Acute kidney injury is a common complication in patients hospitalized with COVID-19, has multiple aetiologies, and is usually multifactorial. We present two cases of anti-glomerular basement membrane (anti-GBM) disease diagnosed after SARS-CoV-2 infection, suggesting a causal correlation. Case Reports A 76-year-old female, with chronic kidney disease (serum creatinine 1.5mg/dL), hypertension, weight loss (16 Kg/6 months) and a pancreatic nodule under surveillance, presented to the emergency department with 1 week of nausea, vomits, diarrhoea and oliguria, as well as a history of mild SARS-CoV-2 infection 2 weeks before presentation. Lab work revealed severe anaemia (7.4 g/dL), inflammatory markers elevation, nephrotic proteinuria (proteinuria/creatininuria ratio 30 g/g), leucoerythrocyturia, serum creatinine of 19.3 mg/dL, hyperkalaemia and metabolic acidosis requiring dialysis induction. Renal ultrasound showed signs of chronicity and several cysts. Aetiological study disclosed positive anti-GBM antibody (1800 U/L) and negative ANCA. Complementary study failed to identify pulmonary involvement or neoplasms. Given the severity of the renal dysfunction along with the absence of alveolar haemorrhage, immunosuppression and plasmapheresis were not initiated. Patient was discharged and remains dialysis dependent. A 65-year-old male smoker with type 2 diabetes and combined pulmonary fibrosis and emphysema, presented in the emergency department with 2 months of asthenia, weight loss and anaemia, in addition to dyspnoea and haemoptysis in the past 3 days. Lab work exposed moderate anaemia (9.7 g/dL), elevated inflammatory markers, serum creatinine of 1.18 mg/dL (previously 0.8 mg/dL), leucoerythrocyturia and positive SARS-CoV-2 test. Angio-Computed Tomography exhibited known pulmonary fibrosis and possible bacterial superinfection. Despite antibiotic therapy (10 days of levofloxacin), haemoptysis remained and kidney function continuously worsened (serum creatinine 2.1 mg/dL). Complementary study showed positive ANCA-MPO (1125.4 U/L) and anti-GBM antibody (460.8U/L). Renal ultrasound was innocent. Kidney biopsy revealed: 6 glomeruli with cellular crescents with segmental necrosis, 3 with focal Bowman's capsule rupture; erythrocyte casts; intimal arterial fibrosis; moderate tubular atrophy; diffuse linear deposits of IgG. Immunosuppression was initiated with prednisolone (1 mg/Kg/day), cyclophosphamide (3x 12.5mg/Kg-750 mg, 2x 500 mg), rituximab (2x 1g), immunoglobulin (1x 2 g/Kg) and plasmapheresis (15 sessions). Kidney function continued to deteriorate (maximum serum urea 306 mg/dL, maximum serum creatinine 6.92 mg/dL) requiring dialysis induction 3 weeks after the beginning of immunosuppression. Even though haemoptysis ceased, the patient remains dialysis dependent 8 months after. Conclusion Literature reports an increase of Anti-GBM disease since the beginning of the pandemic. The presented cases support the apparent correlation, suggesting SARS-CoV-2 as a precipitant of this disease by endothelial injury with basal membrane exposure and autoantibody development. In the second case, the authors assume a subacute ANCA-MPO vasculitis with superimposed anti-GBM (eventually precipitated by COVID-19). Even though the causal association is not established, we highlight the importance of clinical suspicion of this rare aetiology in cases of acute kidney injury after SARS-CoV-2 infection.

#4360 FACTORS ASSOCIATED TO RENAL REMISSION IN CRESCENTIC GLOMERULONEPHRITIS

Abstract Background and Aims Impaired renal function is one of the most relevant factors associated to crescentic glomerulonephritis (CGN) prognosis. However, renal remission has not yet been defined and clinicians are required to use systemic scores (such as BVAS) to predict severity. In this retrospective study, we aim to describe the associated factors to long-term chronic dialysis incidence and survival in CGN. Method We included all biopsy-proven CGN of our center between 2004 and 2022. At baseline, demographics, treatments and comorbidities were collected. Renal function was assessed by glomerular filtration rate (GFR) using CKD-EPI equation, quantification of proteinuria and demonstration of hematuria. During follow-up (median 1486, interquartile range [25-3082] days) renal and vital status was evaluated. Factors associated to dialysis requirement were assessed using Cox regression models. A combined endpoint of death and dialysis was established. Factors associated to the combined endpoint were assessed. Results We included 47 CGN (77% female, 67±15 years). Of them, 35 (75%) presented positive ANCA antibodies, 3 (6%) positive glomerular basement membrane (GBM) antibodies, 8 (17%) ANCA and GBM antibodies and one (2%) presented negative autoimmunity. Induction treatment was based on prednisone and cyclophosphamide in 43 patients (91%), prednisone and rituximab in 3 (6%) and prednisone alone in one (2%). At admission, median CKD-EPI was 11 (11-21) ml/min/1.73 m2, proteinuria was 1030 (552-1872) mg/g and 43 (91%) patients presented hematuria. Nineteen patients (40%) required dialysis at admission. Following the definition of KDIGO guidelines for renal remission, 28 (64%) patients achieve it at 6 months. During follow-up, fifteen patients (36%) started chronic dialysis. Factors associated to chronic dialysis were the type on CGN (dual ANCA and GBM and GBM (+) vs ANCA (+), p = 0.003), CKD-EPI at admission (p = 0.001), AKIN (p = 0.050), requirement of dialysis at admission (p<0.001), percentage of crescents (p = 0.037), proteinuria at admission (p = 0.046) and remission after induction treatment (p<0.001). Twenty-four patients (53%) died or needed dialysis during follow-up. Factors associated to this combined endpoint were CKD-EPI at admission (p = 0.017), type on CGN (dual ANCA and GBM vs others, p = 0.003) (Figure 1), debut in dialysis (p<0.001), remission after induction treatment (p<0.001). An adjusted Cox regression model demonstrated that the need for dialysis or death during follow-up was independently associated to not achieving remission after induction (i.e. 6 months) (HR 8.78, 95%CI (2.88-26.7), p<0.001) and requirement of dialysis at debut (HR 3.96, 95%CI [1.15-13.6], p = 0.029). Conclusion The requirement of dialysis at debut and not achieving remission after induction are independent predictors of death or need for chronic dialysis in CGN.

E017 ANCA-associated but not vasculitis

Abstract Background/Aims A 72-year-old lady presented in primary care with complaints of generalised body aches, bilateral leg weakness and constitutional symptoms following a first dose of COVID-19 vaccine. Blood tests showed slightly raised inflammatory markers. She was initially diagnosed with polymyalgia rheumatica and was started on 40 mg prednisolone with minimal improvement. Methods The examination in the rheumatology clinic was unremarkable. Investigations revealed raised white cell count, consistent with high dose steroid treatment, and elevated monocytes. There was mild improvement in inflammatory markers. The working diagnosis was of self-limiting viral illness. Further testing discovered strongly positive MPO ANCA (115 IU/ml), and the patient received three pulses of 500 mg methylprednisolone for suspected vasculitis arranged by the medical team. There was no evidence of renal involvement. The diagnosis made at this point was autoimmune inflammatory disorder with unclear aetiology. At the subsequent clinic visit she reported mild shortness of breath, but no other symptoms suggestive of either vasculitis or connective tissue disease. Repeat ANCA showed significant reduction in MPO titre following pulse steroid treatment. CT of chest, abdomen and pelvis demonstrated a localised lobular/nodular deformity of the liver. Viral hepatitis screen was negative. CA19-9 was raised at 100 U/ml. Liver biopsy was reported as poorly differentiated carcinoma without specific localising immunohistochemical features. Results The patient underwent hemi-hepatectomy for histologically confirmed pT2pNXM0R0 liver cholangiocarcinoma in a tertiary centre followed by adjuvant chemotherapy with capecitabine. With treatment, her MPO ANCA and CA19-9 levels declined. An interval CT scan of chest, abdomen and pelvis performed ten months after the surgery, showed no recurrence of malignancy. Given the fact that the patient’s MPO ANCA fell following the treatment of cholangiocarcinoma, it is likely that positive MPO ANCA is associated with underlying malignancy rather than an active vasculitis. Conclusion This unusual case describes an evolution of the diagnostic process guided by non-specific symptoms and ANCA positivity, arriving at an unexpected diagnosis of malignancy. Although ANCA is a sensitive and specific marker of vasculitides, it can be positive in other conditions particularly hepatitis B, inflammatory bowel disease and autoimmune liver disorders. Malignancy can also be associated with ANCA in the absence of vasculitis. In one study, of 118 ANCA positive patients without ANCA-associated vasculitis, four were found to have malignancy. In a study of 1024 patients who had ANCA tested, 61 patients were found to have malignancy, predominantly haematological and lung cancers. However, after adjustment for sex, age and time of blood draw, no association was found between ANCA status and incidence of cancer. Interestingly, paraneoplastic vasculitis such as polyarteritis nodosa (PAN) has been described in the context of underlying cholangiocarcinoma, and is associated with ANCA rise. Moreover, patients with raised ANCA and PAN also have raised CA 19-9. Disclosure V. Saulite: None. S. Dahiya: None.

E021 A rare case of coexistence of ANCA-associated vasculitis and malignancy

Abstract Background/Aims A 65-year-old man, with a background of COPD, peripheral vascular disease and a neurostimulator in situ for chronic back pain, presented with a range of symptoms initially treated as lower respiratory tract infection in the community. He complained of bitemporal headache, jaw-pain, transient visual loss and had raised inflammatory markers (CRP 157 and ESR 105). He was subsequently treated as giant cell arteritis with 60mg prednisolone daily despite equivocal temporal artery ultrasound. He continued to have drenching sweats, arthralgia, epistaxis, shortness of breath and haemoptysis although inflammatory markers had normalised. Immunology revealed a strongly positive anti-PR3 antibody at > 8 units suggestive of granulomatosis polyangiitis. There was no convincing end organ evidence of vasculitis. CT-chest identified nodules and non-specific inflammatory changes but no cavitation or pulmonary haemorrhage. He was intolerant of steroids with significant insomnia and mood changes therefore they were rapidly tapered to 20mg daily. Methods He was readmitted to hospital on 20mg prednisolone with acute abdominal pain. CT abdomen-pelvis showed a lesion at the hepatic flexure suspicious for colon cancer, and this was confirmed on colonoscopy and biopsy. PET-CT at this time showed no evidence for active large vessel vasculitis. His prednisolone was tapered further and omitted prior to right hemicolectomy. Histology revealed definitive adenocarcinoma along with a focus of necrotising vasculitis and granulomas in the subserosa close to the tumour, with a distant granulomatous lesion at the resected appendix. He developed post-operative ileus and desaturated leading to a CTPA which did not show PE but identified progressive enlargement of the pulmonary nodules reported as suspicious of metastases. Throughout this time PR3 remained elevated and repeat PET-CT off steroids showed increased uptake at the aorta and right common iliac artery suggestive of active vasculitis. The FDG uptake and rate of enlargement of the pulmonary nodules was felt to be out of keeping with metastases and an inflammatory cause was suspected. Results Episodic pyrexia continued with no identifiable infective source and so a decision to commence oral prednisolone 40 mg was made. Repeat PET-CT 4 weeks later showed complete resolution of the inflammation in the aorta and right common iliac and reduction in size of the lung nodules. Unfortunately, the patient developed acute pancreatitis on steroids, so the prednisolone was reduced to 20mg with a view to induction therapy with cyclophosphamide. Conclusion This case highlighted multiple diagnostic challenges with clinical features of large vessel involvement in a patient with a positive ANCA and concomitant occult malignancy. Co-existence of a vasculitis and a neoplastic disease is rare. ANCA positive vasculitis is most commonly reported with haematological malignancies but less so in solid tumours, presenting as a paraneoplastic phenomenon. This case also highlighted the challenges in management when both conditions co-exist. Disclosure S. Ahmed: None. E. Pathan: None. P. Brown: None. J. Heaney: None. A. Pratt: None.

P204 Biomechanical Phenotype of Circulating Neutrophils Is Altered in ANCA Associated Vasculitis

Abstract Background/Aims Real Time-Deformability Cytometry (RT-DC) is a novel technique able to identify morpho-rheological characteristics of individual cells such as size, deformability, and elasticity using only 50µl of whole blood. Cells in suspension flow through a microfluidic channel while hydrodynamic force is applied, leading to reversible deformation of individual cells from shear stress and pressure gradients. Cell brightness and area can be used to identify individual cell types. The morpho-rheological characteristics of immune cells in ANCA associated vasculitis (AAV) are unknown. Methods Whole blood from healthy controls (HC), patients with active AAV, or patients with AAV in remission was analysed using RT-DC. The diagnosis of AAV was based upon positive ANCA testing, with either (i) pauci-immune glomerulonephritis, or (ii) typical clinical features of extra-renal AAV. Patients with active disease may have received steroids prior to sampling but those who received other immunosuppression or cytotoxics were excluded. Remission was defined as BVAS of 0 with prednisolone dose ≤7.5mg/day. Blood was collected into K2 EDTA and diluted 1:20 in 1xPBS/0.6% methylcellulose. Cell suspensions were flowed across a Flic20 polydimethylsiloxane microfluidic chip, containing reservoirs connected by a measurement channel with a 20x20 μm2 cross-section. RT-DC measurements were collected at a flow rate of 0.12μL/s using a high-speed CMOS camera to capture images at a rate of 2000 frames/second. ShapeOut software was used to calculate cell size, deformation, and elasticity. Results There was no difference in neutrophil size between patients with active AAV (n = 15), patients with AAV in remission (n = 31), and HC (n = 15). Neutrophils from patients with active AAV were significantly stiffer than patients in remission or HC, displaying decreased deformation (median 0.084, 0.085, and 0.078 au respectively, p = 0.0068) and increased elasticity (median 0.973, 0.968 and 1.006 au respectively, p = 0.0196). In patients with active AAV, there was strong inverse correlation between neutrophil deformation and disease activity measured by BVAS score (r=-0.573, p = 0.032). Neutrophils isolated from healthy donors exhibited a trend towards decreased deformability when primed with TNF and stimulated with MPO-ANCA IgG compared to unstimulated or cells treated with healthy donor IgG (median 0.086, 0.085, and 0.083 for unstimulated, control IgG, and MPO-ANCA IgG respectively, ns). Conclusion Neutrophils from patients display distinct physical properties in active AAV which correlate with disease activity. Similar results are seen when neutrophils are stimulated in vitro with MPO-ANCA IgG. This phenotype of increased cell stiffness may lead to increased neutrophil retention in pulmonary and renal microvasculature, thus increasing the potential for neutrophil-endothelial cell interactions and microvascular damage. Morphorheological parameters can be rapidly measured using a small volume of whole blood; thus, RT-DC may be a useful technique to aid identification of disease activity in AAV and to guide treatment. Disclosure N. Pisacano: None. S.P. McAdoo: None. J. Guck: None. C.D. Pusey: None. E.R. Chilvers: None. A.C. Cowburn: None. K.M. Lodge: None. M.F. Prendecki: None.

P031 Montelukast antagonising underlying systemic illness

Abstract Background/Aims Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare, multisystemic, autoimmune vasculitis involving small to medium-sized blood vessels. It has a well-established affiliation with atopic syndromes, typically adult-onset asthma and sinusitis. More rare associations are linked with drug side effects such as Montelukast. According to the ‘American College of Rheumatology 1990’, the following criteria yield a sensitivity of 84% in identifying a patient with EGPA. The criteria include: asthma, eosinophilia >10% on differential white cell count, mononeuropathy or polyneuropathy, transient pulmonary infiltrates on chest radiography, paranasal sinus abnormality, and blood vessel biopsy demonstrating extravascular eosinophilia, in a patient with symptoms of systemic vasculitis. The multisystemic involvement of EGPA makes both diagnosis and management difficult as presentations can vary. Methods We report the complex case of a 61 year-old gentleman diagnosed with EGPA. His relevant past medical history includes a diagnosis of Asthma in 2002 (managed with inhaled bronchodilators, corticosteroids, and montelukast), recurrent sinusitis, and lower respiratory tract infections. The patient presented with a one month history of abdominal cramping and bloating. This was associated with nausea, constipation, anorexia, and a week of ‘drenching’ night sweats. His full physical examination during this time was unremarkable. Results He had a normal CT Abdomen Pelvis and colonoscopy. His admission chest radiograph demonstrated bilateral parenchymal lung changes. This was followed by a CT Thorax showing bilateral upper and lower lobe bronchiectasis. Mediastinal and hilar adenopathy consistent with a diagnosis of allergic bronchopulmonary aspergillosis with associated reactive adenopathy. His laboratory investigations showed eosinophilia (21.68) and leucocytosis (32.7). In view of these results, an autoantibody screen was sent showing positive ANCA and positive anti-Myeloperoxidase antibodies(MPO titre 55). Two days into his admission he developed pain and paralysis of his right upper limb. He reported marked fatigue followed by a petechial, non-blanching, vasculitic rash on both ankles. Neurological examination reflected a subacute symmetrical sensory and motor polyneuropathy predominantly involving the right side with bilateral foot drop. MRI Brain demonstrated an established infarct in the left external capsule. He was commenced on high dose aspirin. Due to high suspicion for EGPA, methylprednisolone was commenced for 5 days, followed by tapering oral corticosteroid therapy and Rituximab therapy. A skin punch biopsy showed ‘ a vasculopathic type reaction with small vessel vasculitis, associated mixed inflammatory infiltrate which includes some eosinophils’ confirmed his diagnosis. Conclusion A topic of particular relevance to this case is the association between EGPA and montelukast. It has been hypothesised that there may be a relationship between Leukotriene Receptor Antagonist Therapy, specifically Montelukast, with the pathogenesis of EGPA. Some research suggests that treatment with Montelukast permits the decreased need for oral corticosteroids for asthma control. Therefore, suggesting that EGPA could have been masked by corticosteroid therapy. Disclosure Á. Connerton: None.

Prevalence and clinical significance of ANCA positivity in lupus nephritis: a case series of 116 patients and literature review.

Among our LN patients we retrospectively selected those who underwent ANCA testing the day of thekidney biopsy and before the start of induction treatment. Clinical/histopathological features at kidney biopsy and renal outcome of ANCA-positive patients were compared with those of ANCA-negative subjects. We included 116 Caucasian LN patients in the study; 16 patients [13.8%] were ANCA-positive. At kidney biopsy, ANCA-positive patients presented more frequently with an acute nephritic syndrome than ANCA-negative ones; the difference howeverdoes not reach statistical significance [44 vs. 25%, p = 0.13]. At histological evaluation, proliferative classes [100% vs 73%; p = 0.02], class IV [68.8% vs 33%; p < 0.01] and necrotizing tuft lesions [27 vs 7%, p = 0.04] were more frequent, and the activity index was higher [10 vs 7; p = 0.03] in ANCA-positive than in ANCA-negative patients. Despite worse histological features, after a 10-year observation period, there were no significant differences in the number of patients with chronic kidney function impairment (defined as eGFR<60mL/minper 1.73m2) between the ANCA-positive and negative groups [24.2 vs 26.6%, p = 0.9]. This could be the result of the more aggressive therapy, with rituximab plus cyclophosphamide, that ANCA-positive patients received more frequently than ANCA-negative ones [25 vs. 1.3%, p < 0.01]. ANCA-positive LN patients frequently have histological markers of severe activity (proliferative classes and high activity index) that require timely diagnosis and aggressive therapy to limit the development of irreversible chronic kidney damage.

EGPA Phenotyping: Not Only ANCA, but Also Eosinophils

Eosinophilic Granulomatosis with Polyangiitis (EGPA) is a small-vessel necrotizing vasculitis. The anti-neutrophil cytoplasmic antibodies' (ANCA) role in defining clinical EGPA phenotypes is well established. Although the role of eosinophils in disease pathogenesis has been clearly demonstrated, the value of blood eosinophil count (BEC) as a biomarker of disease phenotypes is currently uncertain. We retrospectively analyzed EGPA patients referred to our Immunology Clinic. Demographic, laboratory and clinical features were retrieved from clinical records, and a Logistic Regression was fitted to evaluate the predictive power of all baseline clinical and laboratory features to define EGPA phenotypes. 168 patients were recruited. BEC ≤ 1500 cells/mL was predictive of a clinical involvement characterized by asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and lung opacities (OR 0.18, 95% CI 0.07-0.43; respiratory-limited phenotype); BEC > 3500/mL was predictive of extrapulmonary organ involvement (OR 3.5, 95% CI 1.7-7.1; systemic phenotype). BEC was also predictive of peripheral nervous system (PNS) involvement, with a positive trend with increasing BEC (<1500/mL: OR 0.17, 95%CI, 0.06-0.47; >3500/mL: OR 2.8, 95% CI, 1.5-5.28). ANCA positivity was also predictive of extrapulmonary involvement (OR 4.7, 95% CI 1.9-11.99). according to BEC and irrespective of the ANCA status, two EGPA phenotypes could be identified, named systemic and respiratory-limited phenotypes, with different organ involvement and possibly different prognoses.

P100 Atypical Anti-Neutrophil Cytoplasmatic Antibodies Are Antibodies Against Neutrophil Extracellular Traps: A Novel Pathophysiological Mechanism In Ulcerative Colitis

Abstract Background The number of mucosal neutrophils, as well as the presence of neutrophil extracellular traps (NETs), correlate with disease activity in Ulcerative colitis (UC), an inflammatory bowel disease. Most (~80%) UC patients present atypical Anti-Neutrophil Cytoplasmatic Antibodies (a-ANCAs) to a yet unknown antigen, which shows a different immunofluorescence staining pattern when compared to cytoplasmatic (c-ANCA) and perinuclear (p-ANCA) that target proteinase (PR3) and myeloperoxidase (MPO), respectively. Here, we analyzed whether a-ANCAs specifically bind to NETs. Methods Blood neutrophils were treated to form non-lytic NETs using LPS-treated platelets with and without DNAse and Trypsin. Patient biopsies and in vitro-formed non-lytic NETs were incubated with p-ANCA, c-ANCA and a-ANCA positive patient and ANCA negative control serum and processed for immunofluorescence microscopy. Macrophage-mediated clearance of serum-pretreated NETs was analyzed in real-time using Incucyte microscopy. Results Ethanol-fixed neutrophils displayed c-ANCA, p-ANCA patterns, and a-ANCA web-like staining. Only c- and p-ANCA react to DNAse-treated ethanol-fixed neutrophils (Fig 1). Serum containing a-ANCA’s bound to non-lytic NETs that disappeared upon treatment with DNAse and Trypsin whereas c- and p- ANCA binding did not disappear upon DNAse treatment (Fig 2) indicating that both DNA and proteins are needed for a-ANCAs to bind to non-lytic NETs. In inflamed colonic tissue of UC patients, a-ANCA co-stained with extracellular DNA and neutrophil elastase covering the intestinal epithelium (Fig 3). In vitro, NETs were efficiently cleared by macrophages, which was strongly inhibited after pre-incubating with a-ANCAs (Fig 4). Macrophages exposed to a-ANCA-incubated NETs expressed higher CXCL-8 and IFN-B levels than the NETs exposed to control serum (both p&amp;lt;0.05). Figure 1 Figure 2 Figure 3 Figure 4 Conclusion a-ANCAs specifically bind to de novo DNA-protein antigens in non-lytic NETs, which prevents efficient macrophage-mediated clearance and induces a pro-inflammatory (M1) phenotype. This inflammatory milieu may contribute to the pathophysiology of UC.

P889 Serologic response with antimicrobial antibodies during the preclinical phase of inflammatory bowel disease

Abstract Background Previous data have shown that the inflammatory process underlying ulcerative colitis (UC) and Crohn’s disease (CD) can start years before the diagnosis. Serum proteomic and serologic markers have been identified during this period, providing the opportunity for early detection of the initial immune disturbances. Our aim was to determine if patients with an incidental diagnosis of UC or CD demonstrate a serologic response based on antimicrobial antibodies, therefore preceding the symptomatic onset of the disease. Methods We performed a prospective single-center study including all asymptomatic subjects with a diagnosis of UC or CD during the colorectal cancer screening program and available data on antimicrobial antibodies between 01/10/2013 – 29/02/2022. The diagnosis of IBD was established by a combination of clinical data, endoscopic findings suggestive of UC or CD, and after histologic confirmation. ASCA IgA, ASCA IgG (EliA ASCA IgA/IgG, ThermoFisher) and ANCA (EUROPattern, PerkinElmer; EliA IgG, ThermoFisher) antibodies were determined. Positive results were considered above 10 U/mL for ASCA, 3.5 for ANCA-MPO and 2.00 for ANCA-PR3. Descriptive statistics were used. Results A total of 26 incidentally-diagnosed patients were included, 19 with UC (21% left-sided, 32% extensive; 53% former smokers), and 7 with CD (57% ileal, 29% colonic; 14% active smokers), with a median age of 51 years (IQR, 51-57). Three patients showed at least one positive test (12%). One patient (5%) with extensive UC showed positive ANCA results, and he developed symptoms 2 months after diagnosis. Two patients (28%) with CD (L2B2 and L1B1, according to Montreal classification) showed positivity to ASCA IgA/IgG at diagnosis, and both have remained asymptomatic after a median of 23 months. After a median follow-up of the whole cohort of 54 months (IQR, 26-67), 12 patients (46%) developed symptomatic disease. Conclusion A low proportion of patients with an incidental diagnosis of IBD demonstrate a serological response based on antimicrobial antibodies, suggesting that this situation corresponds to the initial phases of IBD when systemic immune disturbances might not be detectable yet.

Using a Network-Based Analysis Approach to Investigate the Involvement of S. aureus in the Pathogenesis of Granulomatosis with Polyangiitis.

Chronic nasal carriage of Staphylococcus aureus (SA) has been shown to be significantly higher in GPA patients when compared to healthy subjects, as well as being associated with increased endonasal activity and disease relapse. The aim of this study was to investigate SA involvement in GPA by applying a network-based analysis (NBA) approach to publicly available nasal transcriptomic data. Using these data, our NBA pipeline generated a proteinase 3 (PR3) positive ANCA associated vasculitis (AAV) disease network integrating differentially expressed genes, dysregulated transcription factors (TFs), disease-specific genes derived from GWAS studies, drug-target and protein-protein interactions. The PR3+ AAV disease network captured genes previously reported to be dysregulated in AAV associated. A subnetwork focussing on interactions between SA virulence factors and enriched biological processes revealed potential mechanisms for SA's involvement in PR3+ AAV. Immunosuppressant treatment reduced differential expression and absolute TF activities in this subnetwork for patients with inactive nasal disease but not active nasal disease symptoms at the time of sampling. The disease network generated identified the key molecular signatures and highlighted the associated biological processes in PR3+ AAV and revealed potential mechanisms for SA to affect these processes.

Churg-Strauss syndrome presented as Pseudo-Foster-Kennedy syndrome: a case report

A 52-year-old woman with bronchial asthma, frequent sneezing, and a skin lesion has suddenly developed poor vision for 15 days in the left eye. Her presenting vision was 6/18 and perception of light was positive in the right and left eyes, respectively, with mild pallor in the right optic disc and disc swelling in the left eye. She had a high eosinophil count, positive ANCA, and a skin biopsy in favor of Churg-Strauss disease. The patient was diagnosed with left optic neuropathy as a result of arteritis, which is a component of Churg-Strauss syndrome (CSS), and was treated with Inj. Methylprednisolone pulse therapy, followed by oral prednisolone but preceded to no perception of light in the left eye after 7 days of follow-up. Although CSS is a rare disease, routine checkup by an ophthalmologist can save vision and identify the high-risk group for proper referral to prevent unwanted morbidity and mortality.

Baseline Eosinophil Count as a Potential Clinical Biomarker for Clinical Complexity in EGPA: A Real-Life Experience.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a small-vessel necrotizing vasculitis with multiple organ involvement. Despite improvements in clinical management, biomarkers for organ involvement and disease prognosis are still an unmet need. EGPA patients referred to our immunology clinic were retrospectively reviewed. Demographic/clinical features, eosinophils, ANCA status, eosinophil cationic protein (ECP) and total serum IgE were evaluated at the baseline. Eosinophils, total serum IgE, ECP and ANCA were studied as possible biomarkers for lung and extrapulmonary disease. In total, 167 EGPA patients were recruited for our study. A positive association between eosinophils and peripheral nervous system (PNS) involvement was demonstrated (p &lt;0.001; chi-squared test). Receiver operating characteristic (ROC) curves using the eosinophil count or percentage as predictors of PNS involvement yielded AUC values of 0.75 and 0.67, respectively. ANCA positivity was associated with PNS involvement, while no correlations with clinical parameters were found for ECP and total serum IgE. Patients without extrapulmonary involvement had lower eosinophils (eosinophils: 2844.7 ± 1698 vs. 6373 ± 5468, p &lt; 0.001; eosinophil percentage: 24.6 ± 10% vs. 36.2 ± 15.8, p &lt; 0.001) and were less likely to be ANCA+ (p &lt; 0.001, chi-squared test). Eosinophils in EGPA are an important biomarker and are associated with extrapulmonary involvement. These findings could strengthen the role of anti-eosinophilic drugs in improving extrapulmonary disease.