Propylthiouracil-induced antineutrophil cytoplasmic antibody-associated vasculitis

Kidney Failure in Pauci-immune Crescentic Glomerulonephritis: Rationale for Immunosuppression to Improve Kidney Outcome

PURPOSE OF REVIEW

Pauci-immune crescentic glomerulonephritis is the hallmark finding in ANCA-associated vasculitis (AAV) when the kidneys are affected. The rationale for immunosuppression in AAV is based on the underlying autoimmune nature of the disease. Overall remission rates, kidney outcomes, and the burden of disease have greatly improved since the discovery of various immunosuppressive therapies, but relapses remain common, and a significant proportion of patients continue to progress to end-stage kidney disease. Here, we review the role of immunosuppressive therapies for the treatment of pauci-immune crescentic glomerulonephritis.

RECENT FINDINGS

Besides the recognized role of B and T cells in the pathogenies of AAV, the focus on the contribution of inflammatory cytokines, neutrophil extracellular traps (NETs), and the complement system allowed the discovery of new therapies. Specifically, the C5a receptor blocker (avacopan) has been approved as a glucocorticoid-sparing agent. Additionally, based on observational data, more clinicians are now using combination therapies during the induction phase. There is also an evolving understanding of the role of plasma exchange in removing ANCA antibodies. Furthermore, the recent development of risk score systems provides physicians with valuable prognostic information that can influence decisions on immunosuppression, although future validation from larger cohorts is needed. The over-activation of various immune pathways plays a significant role in the pathogenesis of pauci-immune crescentic glomerulonephritis in AAV. Immunosuppression is, therefore, an important strategy to halt disease progression and improve overall outcomes. Relapse prevention while minimizing adverse events of immunosuppression is a major long-term goal in AAV management.

Propylthiouracil-Induced Antineutrophil Cytoplasmic Antibody-Associated Vasculitis with Overlap IgA Nephropathy: A Case Report

Background

The anti-thyroid medication propylthiouracil (PTU) is a recognised cause of drug-induced antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Pauci-immune crescentic glomerulonephritis is the characteristic feature of this condition on renal biopsy. We present a case of PTU-induced AAV with the unusual histological finding of overlap IgA nephropathy (IgAN) in a young female with treatment-resistant Graves' disease.

Case Report

A 26-year-old female presented with an acute kidney injury, macroscopic haematuria, and proteinuria 14 months after starting PTU for Graves' disease. She had a history of established thyroid eye disease and a previous severe adverse reaction to carbimazole. Her autoantibodies were strongly positive for myeloperoxidase-ANCA (199 U/mL). Renal biopsy demonstrated both necrotising crescentic glomerulonephritis and prominent (3+) mesangial deposition of IgA. She was treated with glucocorticoids and rituximab with sustained improvement in her renal function but persisting mild proteinuria and microscopic haematuria. PTU was ceased following a dose of radioactive iodine (RAI). Twelve months post-RAI, her Graves' orbitopathy remained stable, and her thyroid function was gradually normalising.

Conclusion

This was a case of drug-induced AAV with histological features of overlap IgAN. We suggest that this patient had pre-existing subclinical IgAN and then developed AAV secondary to PTU. The management of her thyroid disease was complex given the PTU-induced vasculitis, previous reaction to carbimazole, the risks of a thyroidectomy on immunosuppression, and the possible worsening of her eye disease with RAI. The glucocorticoids and Rituximab prescribed for vasculitis may have prevented the progression of her Graves' orbitopathy after RAI.

Propylthiouracil-induced vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune condition characterized by necrotizing inflammation of small vessels throughout the body. Pharmaceutical agents have been noted as an emerging etiology. This case presents a 41-year-old woman with a longstanding history of Graves' disease who previously failed other interventions and was started on propylthiouracil (PTU) nearly 2 years prior to symptom onset. The patient presented with severely pruritic purpuric lesions on her lower extremities that transformed into large bullae and became extremely painful. A thorough workup revealed only slightly elevated perinuclear ANCA and a mild protein S deficiency. Tissue biopsy was consistent with thrombotic vasculitis. A presumptive clinical diagnosis of PTU-induced vasculitis was made. Because the condition is relatively uncommon, the best course of treatment has not clearly been defined. Though PTU was immediately discontinued, the patient also required corticosteroids and referral for tissue debridement. While some cases have had symptom resolution after cessation of PTU, this case adds to a growing body of evidence for the timely use of corticosteroids in controlling PTU-induced vasculitis.

New Insights into Pathogenesis and Treatment of ANCA-Associated Vasculitis: Autoantibodies and Beyond

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a group of rare systemic diseases affecting small-caliber vessels. The damage caused by AAV mainly involves the lung and kidneys. AAV includes three different types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Although the different phenotypic forms of AAV share common features, recent studies have shown that there are significant differences in terms of pathogenetic mechanisms involving both the adaptive and innate immune systems. Advances in our understanding of pathogenesis have enabled the development of immuno-targeted therapies. This review illustrates the characteristics of the various forms of AAV and the new therapies available for this disease that can have lethal consequences if left untreated.

Pathogenesis of anti-neutrophil cytoplasmic antibody-associated vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) encompasses a group of potentially life-threatening disorders characterized by necrotizing small vessel vasculitis with positive serum ANCA. To date, the pathogenesis of AAV has not been fully elucidated, but remarkable progress has been achieved in the past few decades. In this review, we summarize the mechanism of AAV. The pathogenesis of AAV involves various factors. ANCA, neutrophils, and the complement system play key roles in disease initiation and progression, forming a feedback amplification loop leading to vasculitic injury. Neutrophils activated by ANCA undergo respiratory burst and degranulation, as well as releasing neutrophils extracellular traps (NETs), thus causing damage to vascular endothelial cells. Activated neutrophils could further activate the alternative complement pathway, leading to the generation of complement 5a (C5a), which amplifies the inflammatory response by priming neutrophils for ANCA-mediated overactivation. Neutrophils stimulated with C5a and ANCA could also activate the coagulation system, generate thrombin, and subsequently cause platelet activation. These events in turn augment complement alternative pathway activation. Moreover, disturbed B-cell and T-cell immune homeostasis is also involved in disease development. In-depth investigation in pathogenesis of AAV might help to offer more effective targeted therapies.

Diagnosing and treating ANCA-associated vasculitis: an updated review for clinical practice

ANCA-associated vasculitides (AAV) are a group of rare, primary, systemic necrotizing small-vessel vasculitides. Granulomatosis with polyangiitis and microscopic polyangiitis account for ∼80–90% of all AAV. Exposure to silica dust, farming and chronic nasal Staphylococcus aureus carriage are associated with increased risk of developing AAV. When a diagnosis of AAV is suspected, as in patients with multisystem organ dysfunction or those with features such as chronic recurrent rhinosinusitis, cavitated lung nodules, palpable purpura or acute kidney injury, then appropriate further investigations are needed, including ANCA testing. In this scenario, a structured clinical assessment should be conducted, evaluating all the organs possibly involved, and tissue biopsy may be necessary for confirmation of the diagnosis. Therapeutic algorithms vary based on the severity of AAV, the clinical diagnosis/ANCA specificity, and the patient’s age, weight, comorbidities and prognosis. Recent data favour rituximab as a preferable option for both induction and maintenance of remission. In addition, regimens with less glucocorticoids are equally effective and safer in inducing remission compared with conventional regimens, and avacopan is an effective glucocorticoid-sparing option. In contrast, there is not compelling evidence to support the routine use of plasma exchange in addition to standard remission-induction therapy in AAV. ANCA and other biomarkers can be helpful in association with clinical assessment to guide diagnosis and treatment decisions. Patients should be frequently evaluated during follow-up for possible disease relapses or treatment-related morbidity, and for monitoring damage accrual, especially metabolic and cardiovascular damage.

Environmental factors influencing the risk of ANCA-associated vasculitis

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

Propylthiouracil-Induced Skin Vasculitis

The use of propylthiouracil (PTU) is associated with the development of autoantibodies, namely, antineutrophil cytoplasmic antibodies (ANCAs), which are associated with the pathogenesis of ANCA-associated systemic vasculitis, most often related to the myeloperoxidase subtype (ANCA-MPO). The authors report the case of a 61-year-old woman on PTU for one year who was referred to Internal Medicine for a three-month evolution of painless non-blanching purple patches, non-pruriginous, involving the chest and legs. The autoimmunity revealed ANCA antibody positivity, with a cutaneous biopsy compatible with leukocytoclastic vasculitis/necrotizing vasculitis with involvement of small and medium-sized vessels. Clinical improvement was noted after the drug was discontinued, with the resolution of the analytical changes.

[Pathogenesis of ANCA-associated vasculitides in 2021: An update]

Anticytoplasmic neutrophil antibodies (ANCA)-associated vasculitis (AAV) are rare systemic immune-mediated diseases characterized by small vessel necrotizing vasculitis and/or respiratory tract inflammation. Over the last 2 decades, anti-MPO vasculitis mouse model has enlightened the role of ANCA, neutrophils, complement activation, T helper cells (Th1, Th17) and microbial agents. In humans, CD4T cells have been extensively studied, while the dramatic efficacy of rituximab demonstrated the key role of B cells. Many areas of uncertainty remain, such as the driving force of GPA extra-vascular granulomatous inflammation and the relapse risk of anti-PR3 AAV pathogenesis. Animal models eventually led to identify complement activation as a promising therapeutic target. New investigation tools, which permit in depth immune profiling of human blood and tissues, may open a new era for the studying of AAV pathogenesis.

Pathogenesis-based new perspectives of management of ANCA-associated vasculitis

While the pathogenesis of anti-neutrophil cytoplasmic autoantibody associated vasculitis (AAV) is still not fully elucidated, there is a mounting evidence that it is initiated by inflammation and activation of innate immunity in the presence of predisposing factors, innate immunity, aberrant responses of the adaptive immune system, and complement system activation. Biologics targeting inflammation-related molecules in the immune system have been explored to treat AVV, and these treatments have provided revolutionary advances. When focusing on the pathogenic mechanisms of AVV, this review presents the new findings regarding novel therapeutic approaches for the management of these conditions.

Propylthiouracil-Induced Antineutrophil Cytoplasmic Antibody-Associated Vasculitis after COVID-19 Vaccination

We report the case of a patient who developed antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) after receiving the coronavirus disease 2019 (COVID-19) vaccine BNT162b (Pfizer–BioNTech). A 37-year-old Japanese woman had been taking propylthiouracil for Graves’ disease. She had erythema on her forearm on the 12th day after receiving the first dose of the vaccine, fever on the 13th day, and redness and swelling of her left auricle on the 25th day. Her serum myeloperoxidase-ANCA and proteinase 3-ANCA levels, which were negative before the Graves’ disease treatment, were elevated. She had unilateral auricular symptoms but no other typical relapsing polychondritis findings. She was diagnosed with propylthiouracil-induced AAV. She was treated with oral glucocorticoids, and her symptoms improved. Propylthiouracil is considered to be the main cause of the onset of AAV in this case, but it cannot be ruled out that BNT162b may have had some effect on the onset of the disease. Although the development of propylthiouracil-induced AAV in this case may have been incidental and unrelated to the vaccination, this report provides important data for evaluating the safety of the vaccine.

A worldwide pharmacoepidemiological update of drug-associated ANCA-associated vasculitis at the time of targeted therapies

OBJECTIVE

The literature data supporting the role of a drug in the onset of drug-associated anti-neutrophil cytoplasmic antibody-associated vasculitis (DA-AAV) mainly rely on case reports or short series and implicate old treatments. The advent of new treatments may have modified the epidemiology of these adverse drug reactions (ADRs). We therefore aimed to update this list by using a pharmacovigilance-based data mining approach.

METHODS

We collected data on ADRs reported with the MedDRA preferred term "Anti-neutrophil cytoplasmic antibody positive vasculitis" up to November 2020 from the World Health Organization pharmacovigilance database (VigiBase^® ). For each retrieved drug, a case/noncase analysis was performed, and disproportionate reporting was calculated by using the information component (IC). A positive IC₀₂₅ value, which is the lower end of the 95% credibility interval, was considered significant.

RESULTS

A total of 483 deduplicated individual case safety reports of DA-AAV involving 15 drugs with an IC₀₂₅ >0 were retrieved. DA-AAV occurred in 264 (71.2%, n=371) women, the median age at onset was 62 years [45-72], and the median time to onset between the introduction of the suspected drug and DA-AAV was 9 months [1-36]. DA-AAV occurrence was considered serious in 472 (97.7%, n=481) cases and fatal in 43 (8.9%) cases. The drugs associated with the highest disproportionate reporting were hydralazine, propylthiouracil, thiamazole, sofosbuvir, minocycline, carbimazole, mirabegron, and nintedanib.

CONCLUSION

This study strengthens the previously suspected association but also identifies 3 new drugs that may cause DA-AAV. Particular attention should be given to these drugs by prescribers and in experimental studies.

[Purpura in a young woman with hyperthyroidism]

INTRODUCTION

Propylthiouracil (PTU) is a synthetic antithyroid drug that can induce ANCA-associated vasculitis.

OBSERVATION

A 27-year-old woman diagnosed with Graves' disease was on PTU for the past 10 years. She developed purpuric lesions of the legs and on the tip of the nose diagnosed as vasculitis. ANCAs were positive, with anti-MPO and anti-PR3 on blood ELISA. After discontinuation of PTU, she was able to fully recover.

CONCLUSION

All synthetic antithyroid drugs can induce ANCA-associated vasculitis, more often PTU. In most cases, antibodies are directed against MPO. Dual anti-MPO and anti-PR3 positivity is possible, but rare. The mechanism could be through an accumulation of PTU in neutrophils, altering the structure of MPO and making it immunogenic. PTU can also induce ANCA-free or lupus vasculitis, maculopapular rashes or urticaria. Many other drugs can induce ANCA-associated vasculitis.

The performance of the chemiluminescent immunoassay for measuring serum myeloperoxidase and proteinase 3 antibodies

Background

Enzyme‐linked immunosorbent assay (ELISA) has traditionally been used to detect myeloperoxidase (MPO) and proteinase 3 (PR3) antibodies, although it is time‐consuming and physically demanding. As a novel and highly effective immunoassay, we compared chemiluminescent immunoassay (CIA) with ELISA to verify the application value of CIA in MPO and PR3 antibodies detection.

Methods

By ELISA and CIA, serum levels of anti‐MPO and anti‐PR3 antibodies were measured in 63 anti‐neutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV) patients (AAV group), including 47 microscopic polyangiitis (MPA) patients and 16 granulomatosis with polyangiitis (GPA) patients, in addition, 68 patients in interference control group (IC group), 19 healthy subjects in healthy control group (HC group). We compared MPO and PR3 antibodies levels and positive rates measured by these two methods among groups. Relationship and coincidence rate between ELISA and CIA were investigated. Diagnostic values for clinical outcomes for MPO and PR3 antibodies were assessed by receiver operator characteristic (ROC) curve.

Results

In AAV patients, when detecting anti‐MPO (r = .90) and anti‐PR3 (r = .81), CIA was highly correlated with ELISA, companying with highly total (88.89%, 92.06%, respectively) and positive coincidence rates (84.78%, 77.27%, respectively). In HC group, anti‐PR3 positive rate detected by both immunoassay were 0, anti‐MPO almost were 0, which without statistically significant difference (P = .32). In IC group, the total (76.47%, 58.82, respectively) and positive coincidence rates (48.38%, 30.00%, respectively) of anti‐MPO and anti‐PR3 were the lowest, but the negative coincidence rates reached 100%. By CIA, similar to ELISA, the levels of anti‐MPO were significantly higher both in AAV patients (56.00; [4.40‐235.30]) and MPA patients (98.00; [27.90‐324.70]) compared with either IC group (3.20; [3.20‐18.55) (P < .0001) or HC group (3.20; [3.20‐3.20]) (P < .0001), yielded an area under curve (AUC) of 0.76 for AAV and 0.89 for MPA, the concentration of anti‐PR3 in GPA group (66.65; [24.43‐150.00]) was significantly higher than that in IC group (2.3; [2.3‐10.95]) (P < .0001) and HC group (2.3; [2.3‐2.3]) (P < .0001), with an AUC of 0.92.

Conclusion

Similar to ELISA, CIA was competent to detect MPO and PR3 antibodies in AAV patients and healthy population, thus distinguish AAV patients from IC group and HC group and effectively diagnose MPA and GPA.

ANCA-associated vasculitis

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

An unusual presentation of propylthiouracil-induced anti-MPO and PR3 positive ANCA vasculitis with associated anti-GBM antibodies, IgA nephropathy and an IgG4 interstitial infiltrate: a case report

Background

A number of disease processes can culminate in rapidly progressive glomerulonephritis, including pauci-immune focal segmental necrotising glomerulonephritis, usually seen with positive serum antineutrophil cytoplasmic antibodies (ANCA). Propylthiouracil (PTU) has been associated with drug-induced ANCA-associated vasculitis (AAV), with antibodies against myeloperoxidase (MPO) and proteinase 3 (PR3) present individually and together having been recognised. ‘Double-positive’ vasculitis with ANCA and anti-glomerular basement membrane (GBM) antibodies has also been reported in association with PTU treatment. We present a case of PTU-induced anti-MPO and PR3 positive ANCA vasculitis with associated anti-GBM antibodies, IgA nephropathy and an IgG4 interstitial infiltrate.

Case presentation

A 51-year-old man presented 2 weeks after re-commencing propylthiouracil (PTU) treatment for Graves’ disease, with a severe acute kidney injury and haemato-proteinuria. He demonstrated positive titres for autoantibodies to PR3 (76.9 IU/mL), MPO (28.8 IU/mL) and GBM (94 IU/mL). Renal biopsy demonstrated numerous glomerular crescents, widespread IgG4-positive lymphoplasmacytic infiltrate and mesangial positivity for IgA. PTU was stopped and he was treated with steroids, plasma exchange and cyclophosphamide with sustained improvement in his renal function.

Conclusions

This case of drug-induced AAV presented a unique and intriguing collection of serological and histological features. We propose that the PTU-induced AAV resulted in epiphenomena of anti-GBM antibody production and an IgG4-cell-rich tubulointerstitial infiltrate. It is uncertain whether the mesangial IgA deposition preceded or resulted from the AAV.

2020 international consensus on ANCA testing beyond systemic vasculitis

This document follows up on a 2017 revised international consensus on anti-neutrophil cytoplasm antibodies (ANCA) testing in granulomatosis with polyangiitis and microscopic polyangiitis and focuses on the clinical and diagnostic value of ANCA detection in patients with connective tissue diseases, idiopathic interstitial pneumonia, autoimmune liver diseases, inflammatory bowel diseases, anti-glomerular basement membrane (GBM) disease, infections, malignancy, and during drug treatment. Current evidence suggests that in certain settings beyond systemic vasculitis, ANCA may have clinical, pathogenic and/or diagnostic relevance. Antigen-specific ANCA targeting proteinase-3 and myeloperoxidase should be tested by solid phase immunoassays in any patient with clinical features suggesting ANCA-associated vasculitis and in all patients with anti-GBM disease, idiopathic interstitial pneumonia, and infective endocarditis associated with nephritis, whereas in patients with other aforementioned disorders routine ANCA testing is not recommended. Among patients with autoimmune liver diseases or inflammatory bowel diseases, ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1 who do not have conventional autoantibodies or in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn's disease. In these cases, ANCA should be tested by indirect immunofluorescence as the target antigens are not yet well characterized. Many questions concerning the optimal use of ANCA testing in patients without ANCA-associated vasculitis remain to be answered.

Propylthiouracil-induced antineutrophil cytoplasmic antibody-associated vasculitis and agranulocytosis in a patient with Graves' disease

SUMMARY

This case is the first to describe a patient who experienced concomitant agranulocytosis and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis as an adverse effect of propylthiouracil treatment for Graves' disease. A 42-year-old female with Graves' disease presented to the emergency department (ED) with a 2-week history of fevers, night sweats, transient lower limb rash, arthralgia, myalgia and fatigue. She had been taking propylthiouracil for 18 months prior to presentation. On admission, agranulocytosis was evident with a neutrophil count of 0.36 × 109/L and immediately propylthiouracil was stopped. There was no evidence of active infection and the patient was treated with broad-spectrum antibodies and one dose of granulocyte colony-stimulation factor, resulting in a satisfactory response. On further investigation, ANCAs were positive with dual positivity for proteinase 3 and myeloperoxidase. There was no evidence of end-organ damage secondary to vasculitis, and the patient's constitutional symptoms resolved completely on discontinuation of the drug precluding the need for immunosuppressive therapy.

LEARNING POINTS

Continued vigilance and patient education regarding the risk of antithyroid drug-induced agranulocytosis is vital throughout the course of treatment. ANCA-associated vasculitis is a rare adverse effect of antithyroid drug use. Timely discontinuation of the offending drug is vital in reducing end-organ damage and the need for immunosuppressive therapy in drug-induced ANCA-associated vasculitis. Similarities in the pathogenesis of agranulocytosis and drug-induced ANCA-associated vasculitis may offer insight into an improved understanding of vasculitis and agranulocytosis.

Personalized Medicine in ANCA-Associated Vasculitis ANCA Specificity as the Guide?

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small- to medium-vessel necrotizing vasculitis responsible for excess morbidity and mortality (1). The AAVs, which include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA), are among the most difficult types of vasculitis to treat. Although clinicopathologic disease definitions have been used traditionally to categorize patients into one of these three diagnoses, more recently ANCA specificity for either proteinase 3 (PR3) or myeloperoxidase (MPO) has been advocated for the purpose of disease classification (2). This is because differences in genetics, pathogenesis, risk factors, treatment responses, and outcomes align more closely with PR3- or MPO-ANCA type than with the clinocopathologic diagnosis. Moreover, classifying patients as GPA or MPA can be challenging because biopsies are not obtained routinely in most cases and existing classification systems can provide discrepant classification for the same patient (3). In this review, we address the recent literature supporting the use of ANCA specificity to study and personalize the care of AAV patients (Table 1). We focus particularly on patients with GPA or MPA.

Drug-induced anti-neutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

In recent years, an increasing number of drugs have been proved to be associated with the induction of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This article reviews the latest research progress on drug-induced AAV.

DATA SOURCES

We conducted a comprehensive and detailed search of the PubMed database. The search terms mainly included drug-induced, ANCA, and vasculitis.

STUDY SELECTION

We summarized the original articles and reviews on drug-induced AAV in recent years. The extracted information included the definition, epidemiology, associated drugs, pathogenesis, clinical features, diagnosis, treatment, and prognosis of drug-induced AAV. We also focused on the differences between drug-induced AAV and primary vasculitis.

RESULTS

The offending drugs leading to drug-induced AAV are almost from pharmacologic categories and we need to be vigilant when using these drugs. The pathogenesis of drug-induced AAV might be multifactorial. The formation of neutrophil extracellular traps is an important mechanism for the development of drug-induced AAV. The clinical features of drug-induced AAV are similar to those of primary AAV. Understanding the difference between drug-induced AAV and primary AAV is helpful to identify drug-induced AAV. Stopping the offending drug at once after diagnosis may be sufficient for those patients with mild symptoms. Immunosuppressive therapy should only be used in patients with vital organs involvement.

CONCLUSIONS

Patients with drug-induced AAV usually have a good prognosis if they stop using the offending drug immediately. Recent advances in research on AAV are expected to help us better understand the pathogenesis of drug-induced AAV.

Clozapine-induced antineutrophil cytoplasmic antibody-associated vasculitis: a case report

Clozapine is the most effective antipsychotic medication for refractory schizophrenia, but it has many possible serious side effects, including antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, the rare case reports available have not presented sufficient characteristic features of drug-induced AAV. Herein, we report a case of a 48-year-old Japanese woman with schizophrenia who presented with fever, arthralgia, myalgia and skin rash after 2 years of clozapine treatment. Her C-reactive protein (CRP) level increased, myeloperoxidase ANCA was positive and skin biopsy revealed leukocytoclastic vasculitis. Initially, steroid administration achieved remission, but her symptoms and high CRP levels relapsed every time the steroid dosage was tapered down. Upon discontinuation of clozapine, her symptoms and elevated CRP level immediately improved and the steroid was successfully tapered and discontinued. This outcome suggested that clozapine was the main cause of AAV.

Propylthiouracil-induced anti-neutrophil cytoplasmic antibody-associated vasculitis mimicking Kawasaki disease

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is rare in children and is characterised as necrotising vasculitis predominantly affecting small and medium-sized vessels. Propylthiouracil (PTU), an antithyroid drug, has been implicated in drug-induced AAV. In contrast, Kawasaki disease (KD) is a common systemic vasculitis, typically observed in children, which affects the medium-sized vessels, including the coronary arteries. An 11-year-old girl who developed AAV while receiving PTU therapy for Graves' disease is described. She was admitted to hospital following a 2-day history of fever, cervical adenopathy, cheilitis and papular rash, 3 weeks after an increase in the PTU dose. Despite discontinuation of PTU and the administration of intravenous antibiotic therapy, her clinical condition deteriorated and over the next 2 days she developed severe diarrhoea, conjunctival injection and swelling and redness of the right index finger. Additional findings included liver dysfunction, hydrops of the gallbladder, coagulopathy and urine abnormalities, suggesting glomerulonephritis. She met the diagnostic criteria for KD and received intravenous immunoglobulin (IVIG) combined with prednisolone, with rapid resolution of clinical and laboratory parameters. Peeling of the right index fingertip became evident on Day 12 of admission. Serial ultrasound cardiography demonstrated no evidence of cardiac involvement. A high titre of myeloperoxidase ANCA was detected in the patient's serum on admission, and the titre decreased during the convalescent stage. This case demonstrates that children with PTU-associated AAV may present with clinical features mimicking KD, and that IVIG along with corticosteroid therapy may be effective in treating patients with drug-induced severe systemic AAV.

"NETtling" the host: Breaking of tolerance in chronic inflammation and chronic infection

How and why we break tolerance to self-proteins still remains a largely unanswered question. Neutrophils have been identified as a rich source of autoantigens in a wide array of autoimmune diseases that arise as a consequence of different environmental and genetic factors, e.g. rheumatoid arthritis (RA), lupus, vasculitis, cystic fibrosis (CF) etc. Specifically, neutrophil extracellular trap (NET) formation has been identified as a link between innate and adaptive immune responses in autoimmunity. Autoantigens including neutrophil granular proteins (targeted by anti-neutrophil cytoplasmic antibodies, ANCA) as well as post-translationally modified proteins, i.e. citrullinated and carbamylated proteins targeted by anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein antibodies (ACarPA), respectively, localize to the NETs. Moreover, NETs provide stimuli to dendritic cells that potentiate adaptive autoimmune responses. However, while NETs promote inflammation and appear to induce humoral autoreactivity across autoimmune diseases, the antigen specificity of autoantibodies found in these disorders is striking. These unique autoantigen signatures suggest that not all NETs are created equal and that the environment in which NETs arise shapes their disease-specific character. In this review article, we discuss the effects of different stimuli on the mechanism of NET formation as well as how they contribute to antigen specificity in the breaking of immune tolerance. Specifically, we compare and contrast the autoreactive nature of NETs in two settings of chronic airway inflammation: one triggered by smoking, a recognized environmental NET stimulus in RA patients, and one mediated by Pseudomonas aeruginosa, the most prevalent lung pathogen in CF patients. Finally, we draw attention to novel findings that, together with the specific environmental/chemical stimuli, should be taken into account when investigating how and why antigen specificity arises in the context of NET formation.

A case report dysregulated neutrophil extracellular traps in a patient with propylthiouracil-induced anti-neutrophil cytoplasmic antibody-associated vasculitis

RATIONALE

Neutrophil extracellular traps (NETs) are immune defence systems that release extracellular chromatin and myeloid granules including myeloperoxidase (MPO) to kill pathogens. An experimental animal study recently demonstrated that disordered NETs induced by propylthiouracil (PTU) could contribute to the production of MPO anti-neutrophil cytoplasmic antibody (ANCA) and the development of ANCA-associated vasculitis (AAV). However, the role of dysregulated NETs in the pathogenesis of human AAV remains unclear.

PATIENT CONCERNS

We report a 19-year-old woman with Graves' disease on PTU presented fever, polyarthralgia, and lung hemorrhage with high titer of MPO-ANCA. This patient had a variety of atypical ANCAs and disordered NETs in vitro.

DIAGNOSES

A diagnosis of PTU-induced AAV (PTU-AAV).

INTERVENTIONS

The PTU was discontinued and she was treated with immunosuppressants and plasmapheresis for reducing pathogenic autoantibodies.

OUTCOMES

Clinical manifestations including fever, polyarthralgia, and lung hemorrhage were on remission with a decrease of dysregulated NETs.

LESSONS

The clinical course of this PTU-AAV case indicated that dysregulated NETs would play a role in the development of ANCA and the pathogenesis of AAV.

Genetic Associations and Environmental Exposures in the Aetiopathogenesis of Anti-Neutrophil Cytoplasmic Antibody- Associated Vasculitis: An Updated Review

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a heterogeneous group of rare diseases characterised by necrotising inflammation of the small blood vessels and the presence of ANCA with specificity for proteinase-3 or myeloperoxidase. Genetic susceptibility along with malignancy, drug exposure, and environmental exposures to infectious agents and silica are involved in disease progression. To date, growing evidence has revealed that ANCA specificity defines homogeneous groups of patients more effectively than clinical diagnosis, since proteinase-3 ANCA and myeloperoxidase-ANCA are linked with different genetic backgrounds and epidemiologies. This review presents current and updated knowledge on the central aetiopathogenic role of genetic associations and environmental exposures in AAV; discusses the main mechanisms of ANCA immunogenesis; and highlights the value of ANCA specificity for future classification criteria.

Renal Involvement in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is the most common cause of rapidly progressive glomerulonephritis. ANCAs play an important role in the pathogenesis and diagnosis of AAV. The classic renal lesion in AAV is a pauci-immune necrotizing and crescentic glomerulonephritis. Treatment is divided into 2 phases: (1) induction of remission to eliminate disease activity and (2) maintenance of remission to prevent disease relapse. AAV patients with end-stage renal disease require modification of immunosuppressive strategies and consideration for kidney transplantation. An improved understanding of disease pathogenesis has led to new treatment strategies being tested in clinical trials.

[Drug-induced vasculitis]

INTRODUCTION

Drug-induced vasculitis is reported in almost 10-20 % of vasculitis. Several drugs may be incriminated in their occurrence. Our study aimed to study the epidemiological, clinical, histopathological and evolutionary characteristics of drug-indced vasculitis from a series of cases and to specify the different drugs involved.

METHODS

We conducted a retrospective study during the period from January 2006 to December 2015 from the cases notified to the regional pharmacovigilance center of Sousse, Tunisia. The diagnosis was established according to the criteria proposed by the group of the American college of rheumatology (ACR).

RESULTS

Our study included thirteen cases of drug-induced vasculitis over a ten-year period, with an mean incidence of 1.3 new cases per year. Mean age of patients was 40.84 years. The mean delay from the treatment onset was 14.46 days with extremes ranging from 5 days to six weeks. Most patients had pure skin involvement. Association with other extracutaneous complaints was present in five cases. Cutaneous biopsy was performed in all patients showing a pathological pattern of leukocytoclastic vasculitis, associated with fibrinoid necrosis, extravasation of red blood cells and allergic capillaritis. The outcome was favorable for all patients. The offending drugs in our series were amoxicillin, pristinamycin, rifampicin, fluconazole, metformin, glimepiride, phenobarbital, gabapentin, fenofibrate, ibuprofen, allopurinol, rituximab and tinzaparin.

CONCLUSION

Anamnestic, clinical, biological and histopathological findings allow the early recognition of drug-induced vasculitis. Adequate treatment prevents systemic spreading and a worse prognosis.

Nasal Septal Perforation in Propylthiouracil-Induced Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis

Here, we present the case of a 29-year-old woman with nasal septal perforation and positive myeloperoxidase- (MPO-) anti-neutrophil cytoplasmic antibody (ANCA). She had been diagnosed with Graves' disease and had been treated with propylthiouracil (PTU) for 14 months. A biopsy of the nasal septum revealed an infiltration of inflammatory cells, with no evidence of malignancy or granulomatous change. Because of the use of PTU, destructive nasal lesion, and positive MPO-ANCA, she was diagnosed with drug-induced ANCA-associated vasculitis (AAV) and was treated with prednisolone and methotrexate after the cessation of PTU. Although PTU is known to be the medicine that induces drug-induced AAV, the manifestation of nasal septal perforation in drug-induced AAV is poorly identified. This is the rare case of drug-induced AAV which manifested only nasal septal perforation.

Antithyroid drug induced syndrome that lies in between ANCA vasculitis and lupus-like syndrome in a 40-year-old female with Graves' disease under methimazole therapy: A Case report

We report the case of a 40-year-old Greek female with symptoms of polyarthritis, pruritic rash and positive p-ANCA antibodies, undergoing treatment with Methimazole therapy for Graves’ disease. The rash and the arthritis symptoms promptly disappeared after withdrawal of methimazole, but p-ANCA antibodies remained positive for 6 weeks. By the time that p-ANCA became negative, anti-dsDNA antibodies presented and remained at high titers for 3 months, with no clinical or specific organ disease symptoms. The patient was under close monitoring for the case of potentially life-threating vasculitis of the lung or the kidney and was treated with methylprednisolone. We diagnosed the patient with Antithyroid drug Syndrome, which in our patient presented with arthritis symptoms and had serological features which are commonly found to Antithyroid drug pANCA vasculitis and Antithyroid drug lupus-like syndrome. Physician’s awareness is essential for the diagnosis and treatment of this syndrome in clinical practice, taking into consideration the high frequency of the use of antithyroid agents.

Clinical Characteristics and Outcomes of Propylthiouracil-Induced Antineutrophil Cytoplasmic Antibody-Associated Vasculitis in Patients with Graves' Disease: A Median 38-Month Retrospective Cohort Study from a Single Institution in China

BACKGROUND

This study sought to investigate the clinical characteristics and outcomes of propylthiouracil (PTU)-induced antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in patients with Graves' disease.

METHODS

Sixteen patients diagnosed with PTU-induced ANCA-associated vasculitis at the authors' hospital from January 2010 to June 2017 were analyzed retrospectively.

RESULTS

All 16 patients with PTU-induced ANCA-associated vasculitis were female. The mean age ± standard deviation of the patients was 39.4 ± 15.3 years (range 19-69 years), and the median time of onset was 36 months (range 1-193 months) post-PTU initiation. The median dose at the onset of PTU-induced ANCA-associated vasculitis was 150 mg/day (range 50-300 mg/day). All patients had a positive serum perinuclear staining pattern (p-ANCA) and antibodies directed against myeloperoxidase (anti-MPO). Six patients tested positive for both anti-MPO antibodies and antibodies directed against proteinase-3. Seven (43.8%) patients presented with involvement of a single organ. The kidney was the organ most commonly affected, as 12 (75%) patients were found to have disease involving this organ. PTU was stopped in all patients, corticosteroids were administered to two patients, and immunosuppressive agents and corticosteroids were administered to five patients. Three patients were lost to follow-up. However, the remaining patients achieved remission after a median follow-up period of 38 months (range 6-76 months). Patients who were positive for pANCA and displayed cytoplasmic staining showed negative findings at rates of approximately 53.8% (7/13) and 100% (6/6), respectively, following treatment.

CONCLUSIONS

PTU-induced ANCA-positive vasculitis occurs at varying times and after exposure to various doses of PTU. The condition has a milder course and has a better prognosis after PTU cessation.

ANCA positive relapsing polychondritis, Graves disease, and suspected moyamoya disease: A case report

RATIOINALE

Relapsing polychondritis (RP) is a rare and heterogeneous disease complex of unknown origin which basically affects cartilaginous structures, 40% of which accompanied by rheumatic, hematologic, and endocrine disease. Among them, vasculitis is the most common accompanying type and usually presented with positive antineutrophilic cytoplasmic antibody (ANCA). The presence of ANCA could be primary or drug-induced like propylthiouracil (PTU). Central involvement of RP is very rare, and there is almost no report of cerebral vasculopathy manifested as moyamoya.

PATIENT CONCERNS

A 26-year-old woman complained about recurrent fever, auricular chondritis, ocular inflammation, and arthritis. She had an 8-year drug intake of PTU for Graves disease. Myeloperoxidase antineutrophilc cytoplasmic antibodies (MPO-ANCA) were found positive. Magnetic resonance angiography (MRA) detected multiple intracranial vasculopathy which we highly suspected it as moyamoya disease.

DIAGNOSES

Relapsing polychondritis, Graves disease and suspected moyamoya disease were clinically diagnosed.

INTERVENTIONS AND OUTCOMES

In case of possible PTU-induced vasculitis and the aggravation of vasculopathy, PTU was replaced by Iodine-131 (I) therapy. Induction treatment included oral prednisone 30 mg daily and oral cyclophosphamide 100 mg daily. Symptoms rapidly relieved before discharge. Inflammation markers were normal and MPO-ANCA decreased in 3 weeks after admission. Prednisone was gradually tapered to 7.5 mg daily and at month 10 azathioprine was continued for maintenance.

LESSONS

RP can overlap with Graves disease and moyamoya disease; comprehensive tests should be performed when admission. When relapsing polychondritis is accompanied with Graves disease, especially when ANCA is positive, PTU should be avoided.

Treatment and clinicopathological characteristics of lupus nephritis with anti-neutrophil cytoplasmic antibody positivity: a case-control study

OBJECTIVE

To assess the clinical features, pathological presentations, treatments and outcomes of lupus nephritis (LN) with anti-neutrophil cytoplasmic antibody (ANCA) positivity.

DESIGN

A case-control study.

METHODS

Patients (n=49) were retrospectively included from Jinling Hospital in China if presenting with biopsy-proven ANCA-positive LN between 1985 and 2008. Clinicopathological characteristics and outcomes were analysed and compared with those of a control group (n=1279). We further compared treatment responses and outcomes of ANCA-positive LN patients based on the treatment issued.

RESULTS

The study included 40 women and 9 men (median age 33 years at biopsy): 38 with myeloperoxidase (MPO)-ANCA, 7 with proteinase 3 (PR3)-ANCA and 4 with double positivity. ANCA-positive LN patients exhibited higher haematuria, serum creatinine levels and systemic lupus erythematosus disease activity index scores. On pathological evaluation, class IV LN was predominant, accounting for 61.22% of cases. Light microscopy revealed significantly higher activity index and chronicity index scores, including cellular crescents, interstitial inflammation, tubular atrophy and interstitial fibrosis. ANCA-positive LN patients receiving mycophenolate mofetil as induction therapy had a higher remission rate and better renal outcomes than those receiving cyclophosphamide. During follow-up, end-stage renal disease developed in seven (14.29%) ANCA-positive LN patients, all of them were MPO-ANCA positive.

CONCLUSIONS

The characteristics of ANCA-positive LN were massive haematuria and advanced renal insufficiency. We observed a higher remission rate and better prognoses when using mycophenolate mofetil than when using cyclophosphamide as induction therapy.

The Prevalence and Management of Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis in China

BACKGROUND

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic GPA (EGPA). Myeloperoxidase (MPO) and proteinase 3 (PR3) are the main antigens for ANCA. AAV is a common multisystem autoimmune disease and most of the studies on AAV have been conducted in Western countries. Nowadays in China many efforts are made to investigate this disease.

SUMMARY

This review highlights the progress in the prevalence, management and outcomes of AAV in Chinese patients. With respect to the prevalence of AAV, though there are no precise data, AAV is not rare in the Chinese population. In Chinese patients with AAV there is a striking preponderance of MPA, and MPO-ANCA is much more common than PR3-ANCA. Even in patients with GPA there is a predominance of MPO-ANCA over PR3-ANCA. Propylthiouracil-induced AAV and ANCA-negative pauci-immune glomerulonephritis are stated in this review as well. With respect to the management of AAV, glucocorticoids in combination with cyclophosphamide remain the mainstay of induction therapy. Besides, we describe predictors of different outcomes in Chinese patients, including mortality, relapse, treatment resistance and end-stage renal disease.

KEY MESSAGES

AAV is not rare in the Chinese population. The disease spectrum and subtypes of ANCA are different between patients with AAV in China and Western countries. The treatment strategy for AAV in China is in consistency with that in Western countries. Predictors of different clinical outcomes are provided.

FACTS FROM EAST AND WEST

Treatment options for AAV are shared between the East and West, with corticosteroid combined with cyclophosphamide being the standard regimen for inductive therapy and switching to azathioprine after remission. The major cause of death in treated patients is infection related to immunosuppressive therapy within the first year after diagnosis, and this rate might be higher in China than in Western countries. Western studies demonstrated the efficacy and safety of rituximab for induction of remission in cases with relatively mild disease and maintenance therapy, but this agent is rarely used in China.

Antithyroid Arthritis Syndrome: A Case Report and Review of the Literature

We herein report the case of a 38-year-old Japanese woman with antithyroid arthritis syndrome who experienced severe migratory polyarthritis after the initiation of thiamazole therapy. The patient's symptoms promptly disappeared without any sequelae after the withdrawal of the drug. Antithyroid arthritis syndrome is poorly characterized, and the findings from our literature review indicate that this syndrome exhibits serological features that are distinct from those of antithyroid agent-induced vasculitis syndrome. The absence of autoantibodies, especially anti-neutrophil cytoplasmic antibodies, may help characterize and diagnose antithyroid arthritis syndrome. Furthermore, physicians' awareness of this syndrome is essential for its diagnosis in clinical practice.

Propylthiouracil induced ANCA-associated vasculitis in a 14-year-old girl

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCAs) are the serologic hallmark of ANCA-associated primary small-vessel vasculitides (AAVs), but these antibodies have also been described in other autoimmune diseases such as inflammatory bowel diseases. Furthermore, different drugs are linked to the induction of ANCA, including propylthiouracil (PTU). However progression into clinical overt vasculitis is less common.

CASE-DIAGNOSIS/TREATMENT

We describe the case of a young girl with Graves' disease presenting with fatigue, fever, episcleritis and arthritis. The unexpected double myeloperoxidase/proteinase 3-ANCA positivity triggered a multidisciplinary diagnostic work-up and resulted in the diagnosis of a clinically overt PTU-induced AAV. After PTU-withdrawal and treatment with high-dose corticosteroids, a favorable clinical and biochemical evolution was obtained.

CONCLUSIONS

The use of PTU in the management of hyperthyroidism is not considered first-line treatment in Europe and is even less commonly used in children. Nevertheless, pediatricians should be aware of the possibility of PTU-induced AAV, especially in the presence of multiple ANCA reactivities. Therefore, the use of this drug should be weighed carefully in children.

Genetic architectures of seropositive and seronegative rheumatic diseases

Rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis and some other rheumatic diseases are genetically complex, with evidence of familial clustering, but not of Mendelian inheritance. These diseases are thought to result from contributions and interactions of multiple genetic and nongenetic risk factors, which have small effects individually. Genome-wide association studies (GWAS) of large collections of data from cases and controls have revealed many genetic factors that contribute to non-Mendelian rheumatic diseases, thus providing insights into associated molecular mechanisms. This Review summarizes methods for the identification of gene variants that influence genetically complex diseases and focuses on what we have learned about the rheumatic diseases for which GWAS have been reported. Our review of the disease-associated loci identified to date reveals greater sharing of risk loci among the groups of seropositive (diseases in which specific autoantibodies are often present) or seronegative diseases than between these two groups. The nature of the shared and discordant loci suggests important similarities and differences among these diseases.

Propylthiouracil-associated rapidly progressive crescentic glomerulonephritis with double positive anti-glomerular basement membrane and antineutrophil cytoplasmic antibody: the first case report

We report a case of propylthiouracil (PTU)-induced double antineutrophil cytoplasmic antibody (ANCA) and anti-glomerular basement membrane antibody (anti-GBM antibody) disease causing pulmonary-renal syndrome in a 35-year-old Thai woman with 10-year history of PTU treatment for thyrotoxicosis. She developed clinical symptoms of vasculitis upon receiving long-term PTU treatment. Prednisolone treatment and the switching from PTU to methimazole resulted to short-term clinical improvement. Nevertheless following termination of steroid treatment, she developed recurrent pulmonary hemorrhage and rapidly progressive glomerulonephritis. The kidney biopsy showed crescentic glomerulonephritis with linear IgG deposit on the glomerular basement membrane although transbronchial lung biopsy showed no immune deposit along the alveolar basement membrane. Serum testing for p-ANCA was positive and western blot showed positive antibody to the alpha-3 chain of collagen type IV. Both ANCA and anti-GBM antibody may play a role in the development of end organ damage. To facilitate early and specific intervention, clinicians should be aware of the propensity of PTU to cause lupus-like syndromes with renal involvement. In patients with PTU-induced ANCA-associated glomerulonephritis, serum anti-GBM antibody test may be useful in the early diagnosis of double positive antibodies disease and plasmapheresis should be performed without delay.

Epitope analysis of anti-myeloperoxidase antibodies in propylthiouracil-induced antineutrophil cytoplasmic antibody-associated vasculitis

Introduction

Increasing evidence has suggested that linear epitopes of antineutrophil cytoplasmic antibody (ANCA) directed to myeloperoxidase (MPO) might provide clues to the pathogenesis of propylthiouracil (PTU)-induced ANCA-associated vasculitis (AAV). This study mapped epitopes of MPO-ANCA in sera from patients with PTU-induced MPO-ANCA (with or without vasculitis) and primary AAV, aiming to analyze certain epitopes associated with the development of PTU-induced AAV.

Methods

Six recombinant linear fragments, covering the whole amino acid sequence of a single chain of MPO, were produced from Escherichia coli. Sera from 17 patients with PTU-induced AAV, 17 patients with PTU-induced MPO-ANCA but without clinical evidence of vasculitis, and 64 patients with primary AAV were collected at presentation. Of the 17 patients with PTU-induced AAV, 12 also had sera at remission. The epitope specificities were detected by enzyme-linked immunosorbent assay by using the recombinant fragments as solid-phase ligands.

Results

Compared with patients with PTU-induced MPO-ANCA but without clinical vasculitis, sera from PTU-induced AAV patients showed significantly higher reactivity against the H1 fragment of MPO (optical density values: 0.17 (0.10 to 0.35) versus 0.10 (0.04 to 0.21), P = 0.038) and could recognize a significantly higher number of fragments (two (none to four) versus one (none to two), P = 0.026). Compared with sera from primary AAV patients, sera from PTU-induced AAV patients had significantly higher reactivity to the P fragment and the H4 fragment (47.1% versus 14.1% P < 0.001; 41.2% versus 14.1%, P = 0.034, respectively), and could recognize a significantly higher number of fragments (two (none to four) versus one (none to two), P = 0.013]. Among the 12 PTU-induced AAV patients with sequential samples, the number of fragments recognized in remission was significantly less than that in initial onset (two (none to four) versus none (none to 0.75), P < 0.001].

Conclusions

Linear epitopes of MPO molecules might be associated closely with PTU-induced AAV. In particular, the P and H4 fragments may be important epitopes in PTU-induced AAV.

A 27-year-old woman presenting with refractory hypoxaemic respiratory failure, haemoptysis and thyrotoxicosis: a rare manifestation of propylthiouracil therapy

Pulmonary manifestations of hyperthyroidism not only include pulmonary hypertension and hydrostatic pulmonary oedema, but also treatment/drug-associated pulmonary diseases have to be considered as an exclusion diagnosis. A 27-year-old woman with hypoxaemic respiratory failure under an arterial-venous extra-corporeal membrane oxygenator (AV-ECMO) was admitted to the intensive care unit (ICU). The patient had progressive dyspnoea with haemoptysis, palpitations and failure to thrive. The patient had Graves' disease treated previously with propylthiouracil (PTU). Diffuse alveolar haemorrhage is a non-specific syndrome characterised by evidence of diffuse alveolar damage, exclusion of infectious aetiology and progressively bloodier bronchoalveolar lavage (and/or 20% hemosiderin laden macrophages on cytological examination). PTU associated perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) vasculitis appears to be more common in younger female patients presenting with leukocytoclastic vasculitis, myalgias and arthralgias. The latter compared to non-drug associated ANCA vasculitis which are more common in older males with visceral involvement. PTU-induced ANCA vasculitis prognosis appears to be better compared to primary ANCA syndromes.

Trojan horses: drug culprits associated with antineutrophil cytoplasmic autoantibody (ANCA) vasculitis

PURPOSE OF REVIEW

Antineutrophil cytoplasmic autoantibody (ANCA) vasculitis is a systemic autoimmune disease resulting in small-vessel inflammation caused by pathogenic autoantibodies directed against proteinase 3 or myeloperoxidase. Legal drug culprits have been implicated as causative agents in secondary forms of disease, and a recent burst of reports also implicate levamisole-adulterated cocaine as a culprit.

RECENT FINDINGS

Here, we briefly discuss all drug culprits associated with ANCA vasculitis and then focus on clinical, serologic, therapeutic and mechanistic aspects of four main drug culprits receiving attention of late, namely hydralazine, minocycline, propylthiouracil (PTU) and levamisole-adulterated cocaine.

SUMMARY

Hydralazine, minocycline, propylthiouracil and levamisole-adulterated cocaine use should be closely considered in any patient where ANCA vasculitis is entertained given the wide use of these drugs in the community. Furthermore, medical practitioners should test urine for the presence of cocaine in any patient with presumed ANCA vasculitis, and if positive, then urine should also be tested for levamisole. Clinical features can be severe requiring not only drug cessation and supportive care, but also immunosuppression, plasma exchange in severe cases and dialysis as needed. Clinical trial investigators should strongly consider excluding patients with drug-induced forms of disease and mechanistic inroads are greatly needed in these secondary forms of disease to help elucidate the underlying cause and pathogenesis of ANCA vasculitis.

Clinico-pathological features and outcomes of patients with propylthiouracil-associated ANCA vasculitis with renal involvement

OBJECTIVE

To retrospectively investigate clinico-pathological features and outcomes of patients with renal involvement in propylthiouracil (PTU)-associated antineutrophil cytoplasmic autoantibody (ANCA) vasculitis (PTU-AAV).

METHODS

Clinico-pathological features and outcomes of 12 patients (female 11, average age 32.4 ± 13.8 years) who developed AAV after treatment with PTU were collected and analyzed. ANCA was detected by both immunofluorescence (IF) and enzyme linked immunosorbent assay (ELISA). All patients had renal biopsy.

RESULTS

Twelve patients received PTU for 2-264 months (median 42 months) when PTUAAV was diagnosed. All patients had positive serum P-ANCA, 11 of them were MPO-ANCA, 1 was MPO and PR3-ANCA double positive. All patients presented with hematuria and proteinuria, 5 of them had gross hematuria, urine protein was 1.9 ± 1.6 g/24 h, 7 of 12 (58.3%) patients had renal dysfunction, among them 3 needed initial renal replacement therapy. Renal biopsy showed pauci-immune segmental necrotizing crescentic glomerulonephritis in ten patients, segmental necrotizing glomerulonephritis superimposed on membranous nephropathy in two patients. All patients withdrew PTU and received steroid and immunosuppressive therapy. After a median follow-up of 42 months (range 21-86), 3 patients developed to ESRD, 7 patients entered complete renal remission. Serum ANCA turned negative only in 2 patients, 10 patients had persistent positive serum ANCA. Three patients relapsed with the elevation of serum ANCA level.

CONCLUSION

Renal damage of PTU-AAV could be pauci-immune necrotizing crescentic glomerulonephritis, and necrotizing glomerulonephritis coexisted with membranous nephropathy. Most patients had persistent positive serum ANCA and had a risk of relapse and progression to ESRD even after PTU withdrawal and immunosuppressive therapy.

Enhanced formation and disordered regulation of NETs in myeloperoxidase-ANCA-associated microscopic polyangiitis

Microscopic polyangiitis (MPA) is an ANCA-associated vasculitis that affects small vessels, especially renal glomeruli. We recently demonstrated that the abnormal formation and impaired degradation of neutrophil extracellular traps (NETs) may be crucially involved in the generation of myeloperoxidase (MPO)-ANCA and subsequent development of MPA. This study assessed the formation and regulation of NETs in patients with MPO-ANCA-associated MPA. Peripheral blood samples were obtained from 38 patients with MPO-ANCA-associated MPA, 23 patients with systemic lupus erythematosus (SLE), and 8 healthy controls. IgG eluted from MPO-ANCA-associated MPA sera demonstrated the highest ability to induce NETs, and this ability correlated with disease activity and paralleled ANCA affinity for MPO. Moreover, addition of recombinant human MPO to these IgG samples reduced NET induction. Additionally, MPO-ANCA-associated MPA sera exhibited lower rates of NET degradation that recovered partially upon depletion of IgG. The activity of DNase I, an important regulator of NETs, was also lower in MPO-ANCA-associated MPA and SLE sera. IgG depletion from MPO-ANCA-associated MPA sera partially restored the rate of NET degradation, and addition of DNase I synergistically enhanced this restoration. Addition of anti-MPO antibodies did not inhibit DNase I activity, and some MPO-ANCA-associated MPA sera contained anti-NET antibodies at levels not correlated with MPO-ANCA titers, suggesting the involvement of unidentified autoantibodies as well. The collective evidence suggests a vicious cycle involving MPO-ANCA and the regulation of NETs could be critically involved in the pathogenesis of MPO-ANCA-associated MPA.

Clinical study of renal impairment in patients with propylthiouracil-induced small-vessel vasculitis and patients with primary ANCA-associated small-vessel vasculitis

The aim of this study was to compare renal impairment in patients with propylthiouracil (PTU)-induced small-vessel vasculitis and patients with primary anti-neutrophil cytoplasmic antibody (ANCA)-induced small-vessel vasculitis. The study compared the pathology and clinical conditions of 10 patients with PTU-associated small-vessel vasculitis and 18 patients with primary ANCA-associated small-vessel vasculitis. All patients showed manifestations of renal impairment. Compared with the primary ANCA-induced small-vessel vasculitis, patients with PTU-induced small-vessel vasculitis were mostly female (P<0.05) and deleloped the disease at a younger age (P<0.05). They had a higher positive rate of perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA; P<0.05), lower 24 h proteinuria content, lower serum creatinine (P<0.05) and milder histopathological lesions (P<0.05). A number of them had gross hematuria (P<0.05). They rarely used hormone and cytotoxic drugs (P<0.05) during treatment and had a better prognosis (P<0.05). In conclusion, PTU-induced small-vessel vasculitis has a milder pathology and clinical manifestations with a better prognosis.