Management of ANCA-associated vasculitis: Current trends and future prospects

Avacopan, a Novel Competitive C5a Receptor Antagonist, for Severe Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis

Avacopan is a relatively novel drug with complement antagonizing properties, and it has demonstrated promising outcomes in treating antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis. This review article seeks to investigate the current standard of care for ANCA vasculitis with the combination of avacopan. The current standard therapy involves the usage of daily corticosteroids in addition to either cyclophosphamide or rituximab; however, prolonged use of corticosteroids is known to be associated with various adverse effects. Avacopan was introduced as a possible substitution to alleviate high-corticosteroid dosages. It functions through competitive inhibition of the C5a receptor in the complement system and results in the reduction of neutrophil activation and migration to sites of inflammation. Clinical trials have observed the efficacy of avacopan both in conjunction with standard therapy with corticosteroids and without corticosteroids. The use of avacopan was able to achieve disease remission and improve renal function in patients with ANCA-associated vasculitis. Additionally, the novel treatment did not increase the risk of adverse events during treatment, while also lowering the toxic effects associated with corticosteroid usage. In summary, current evidence supports the success and safety of administering avacopan to treat patients with ANCA-associated vasculitis. Additional clinical trials are warranted to identify optimal dosage and method in using avacopan in the clinical setting.

Pulmonary embolism and diffuse alveolar bleeding: combination options and therapy features

The analysis of the mechanisms of the formation of a rare clinical combination of pulmonary embolism (PE) and diffuse alveolar hemorrhage (DAH), which are complications of systemic vasculitis associated with antibodies to the cytoplasm of neutrophils (primarily granulomatosis with polyangiitis), systemic lupus erythematosus and secondary antiphlogistic syndrome primary antiphospholipid syndrome and Goodpastures syndrome. Taking into account the chronological sequence of the occurrence of PE and DAH, 3 variants of the onset of these potentially fatal additions to the underlying disease were considered: the anticipatory DAH development of PE, delayed from DAH PE and joint (within 24 hours) formation of PE and DAH. A review of single descriptions of such a combination of complications of granulomatosis with polyangiitis is carried out, criteria are indicated, a working classification of severity is given and, taking this into account, a modern program of therapy for DAH as an independent event and in combination with PE.

Neutrophil Extracellular Traps: A Potential Therapeutic Target in MPO-ANCA Associated Vasculitis?

Our understanding of immune recognition and response to infection and non-infectious forms of cell damage and death is rapidly increasing. The major focus is on host immunity and microbiological invasion. However, it is also clear that these same pathways are important in the initiation and maintenance of autoimmunity and the damage caused to targeted organs. Understanding the involvement of cell death in autoimmune disease is likely to help define critical pathways in the immunopathogenesis of autoimmune disease and new therapeutic targets. An important immune responder cell population in host defense and autoimmunity is the neutrophil. One autoimmune disease where neutrophils play important roles is MPO-ANCA Microscopic Vasculitis. This a severe disease that results from inflammation to small blood vessels in the kidney, the glomeruli (high blood flow and pressure filters). One of the best studied ways in which neutrophils participate in this disease is by cell death through NETosis resulting in the discharge of proinflammatory enzymes and nuclear fragments. In host defense against infection this process helps neutralize pathogens however in auto immunity NETosis results in injury and death to the surrounding healthy tissues. The major autoimmune target in this disease is myeloperoxidase (MPO) which is found uniquely in the cytoplasm of neutrophils. Although the kidney is the major organ targeted in this disease MPO is not expressed in the kidney. Autoantibodies target surface MPO on activated circulating neutrophils resulting in their lodgment in glomerular capillaries where they NETose releasing extracellularly MPO and nuclear fragments initiating injury and planting the key autoantigen MPO. It is the cell death of neutrophils that changes the kidney from innocent bystander to major autoimmune target. Defining the immunopathogenesis of this autoimmune disease and recognizing critical injurious pathways will allow therapeutic intervention to block these pathways and attenuate autoimmune injury. The insights (regarding mechanisms of injury and potential therapeutic targets) are likely to be highly relevant to many other autoimmune diseases.

A Comparison of Immunoglobulin Variable Region N-Linked Glycosylation in Healthy Donors, Autoimmune Disease and Lymphoma

N-linked glycans play an important role in immunity. Although the role of N-linked glycans in the Fragment crystallizable (Fc) region of immunoglobulins has been thoroughly described, the function of N-linked glycans present in Ig-variable domains is only just being appreciated. Most of the N-linked glycans harbored by immunoglobulin variable domain are of the complex biantennary type and are found as a result of the presence of N-linked glycosylation that most often have been introduced by somatic hypermutation. Furthermore, these glycans are ubiquitously present on autoantibodies observed in some autoimmune diseases as well as certain B-cell lymphomas. For example, variable domain glycans are abundantly found by anti-citrullinated protein antibodies (ACPA) in rheumatoid arthritis (RA) as well as by the B-cell receptors of follicular lymphoma (FL). In FL, variable domain glycans are postulated to convey a selective advantage through interaction with lectins and/or microbiota, whereas the contribution of variable domain glycans on autoantibodies is not known. To aid the understanding how these seemingly comparable phenomena contribute to a variety of deranged B-responses in such different diseases this study summarizes the characteristics of ACPA and other auto-antibodies with FL and healthy donor immunoglobulins, to identify the commonalities and differences between variable domain glycans in autoimmune and malignant settings. Our finding indicate intriguing differences in variable domain glycan distribution, frequency and glycan composition in different conditions. These findings underline that variable domain glycosylation is a heterogeneous process that may lead to a number of pathogenic outcomes. Based on the current body of knowledge, we postulate three disease groups with distinct variable domain glycosylation patterns, which might correspond with distinct underlying pathogenic processes.

Immunoglobulins G from patients with ANCA-associated vasculitis are atypically glycosylated in both the Fc and Fab regions and the relation to disease activity

Background

Anti-neutrophil cytoplasmic autoantibodies (ANCA) directed against myeloperoxidase (MPO) and proteinase 3 (PR3) are pathogenic in ANCA-associated vasculitis (AAV). The respective role of IgG Fc and Fab glycosylation in mediating ANCA pathogenicity is incompletely understood. Herein we investigate in detail the changes in Fc and Fab glycosylation in MPO-ANCA and Pr3-ANCA and examine the association of glycosylation aberrancies with disease activity.

Methodology

Total IgG was isolated from serum or plasma of a cohort of 30 patients with AAV (14 MPO-ANCA; 16 PR3-ANCA), and 19 healthy control subjects. Anti-MPO specific IgG was affinity-purified from plasma of an additional cohort of 18 MPO-ANCA patients undergoing plasmapheresis. We used lectin binding assays, liquid chromatography, and mass spectrometry-based methods to analyze Fc and Fab glycosylation, the degree of sialylation of Fc and Fab fragments and to determine the exact localization of N-glycans on Fc and Fab fragments.

Principal findings

IgG₁ Fc glycosylation of total IgG was significantly reduced in patients with active AAV compared to controls. Clinical remission was associated with complete glycan normalization for PR3-ANCA patients but not for MPO-ANCA patients. Fc-glycosylation of anti-MPO specific IgG was similar to total IgG purified from plasma. A major fraction of anti-MPO specific IgG harbor extensive glycosylation within the variable domain on the Fab portion.

Conclusions/Significance

Significant differences exist between MPO and PR3-ANCA regarding the changes in amounts and types of glycans on Fc fragment and the association with disease activity. These differences may contribute to significant clinical difference in the disease course observed between the two diseases.

Intravenous pulse methylprednisolone for induction of remission in severe ANCA associated Vasculitis: a multi-center retrospective cohort study

Background

Intravenous pulse methylprednisolone (MP) is commonly included in the management of severe ANCA associated vasculitis (AAV) despite limited evidence of benefit. We aimed to evaluate outcomes in patients who had, or had not received MP, along with standard therapy for remission induction in severe AAV.

Methods

We retrospectively studied 114 consecutive patients from five centres in Europe and the United States with a new diagnosis of severe AAV (creatinine > 500 μmol/L or dialysis dependency) and that received standard therapy (plasma exchange, cyclophosphamide and high-dose oral corticosteroids) for remission induction with or without pulse MP between 2000 and 2013. We evaluated survival, renal recovery, relapses, and adverse events over the first 12 months.

Results

Fifty-two patients received pulse MP in addition to standard therapy compared to 62 patients that did not. There was no difference in survival, renal recovery or relapses. Treatment with MP associated with higher risk of infection during the first 3 months (hazard ratio (HR) 2.7, 95%CI [1.4–5.3], p = 0.004) and higher incidence of diabetes (HR 6.33 [1.94–20.63], p = 0.002), after adjustment for confounding factors.

Conclusions

The results of this study suggest that addition of pulse intravenous MP to standard therapy for remission induction in severe AAV may not confer clinical benefit and may be associated with more episodes of infection and higher incidence of diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1226-0) contains supplementary material, which is available to authorized users.

Serum hepcidin is increased in ANCA-associated vasculitis and correlates with activity markers

Hepcidin is a key regulator of iron metabolism and plays an important role in many pathologies. It is increased by iron administration and by inflammation, while erythropoiesis downregulates its expression. It decreases iron availability and thus contributes to anemia of chronic diseases. The aim of the study was to measure hepcidin as a marker and pathogenetic factor in ANCA-associated vasculitis (AAV). Hepcidin plasma concentration was measured by the immunological method in 59 patients with AAV and compared to patients with non-vasculitic etiology of chronic kidney disease, patients on hemodialysis (HD), with systemic lupus erythematodes (SLE) and to healthy controls and blood donors, and was correlated with the parameters of iron metabolism, inflammation, activity of the process and kidney function. Hepcidin concentration was increased in patients with AAV, SLE and HD and correlated positively with C-reactive protein, serum ferritin and creatinine, and negatively with hemoglobin and serum transferrin. In active form of AAV it correlated with the clinical scoring system (BVAS). Hepcidin can thus be considered as a pathogenetic factor of anemia in AAV and can be used for evaluation of inflammation in AAV and as an additional marker in active forms of the disease.

Antineutrophil cytoplasmic antibody-associated vasculitis, update on molecular pathogenesis, diagnosis, and treatment

Circulating antineutrophil cytoplasmic antibodies (ANCAs) are the central pathogenic mechanism for a group of systemic and renal syndromes called the ANCA-associated vasculitis (AAV). The nomenclature has changed from eponymous labeling to granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and microscopic polyangiitis. These syndromes predominantly affect the pulmonary and renal systems. We also review the molecular pathology behind ANCAs and associated antigens and infections. Various clinical presentations, the multiple target organs affected, and diagnostic challenges involved in identifying these diseases are discussed. Treatment updates are also provided with regard to new studies and the now standard use of anti-CD-20 monoclonal antibodies as first-line therapy in all but the most aggressive presentations of this disease. Maintenance regimens and monitoring strategies for relapse of vasculitis and associated systemic complications are discussed.

Sweet syndrome: a rare feature of ANCA-associated vasculitis or unusual consequence of azathioprine-induced treatment

Background

Sweet syndrome is a rare skin condition characterised by fever, neutrophilia, and tender erythematous skin lesions and has been reported to occur in association with anti-neutrophil cytoplasmic antibodies (ANCA) as well as complicate treatment with azathioprine therapy. Azathioprine, a relatively safe immunosuppressive, is frequently used to maintain disease remission in the treatment of ANCA-associated vasculitis. The occurrence of Sweet syndrome in a patient with ANCA-positive vasculitis and following treatment with azathioprine prompted us to present this clinical case and share this unusually rare occurrence. In doing so, we also wish to discuss current understanding of the disease and plausible associations.

Case presentation

Herein, we discuss the case of a 54-year old white male, who presented with features of ANCA vasculitis with haemoptysis, arthralgia, abnormal kidney function with active urine sediment and a positive p-ANCA titre. Standard immunosuppressive treatment with corticosteroids and intravenous rituximab resulted in disease remission. Due to significant steroid side effects, his steroid treatment was gradually tapered and switched to azathioprine over a 6-month period. Two weeks following initiation of azathioprine, he developed a painful maculo-papular erythematous skin rash and fever. A skin biopsy confirmed classical features consistent with Sweet syndrome. Withdrawal of azathioprine and treatment with oral corticosteroids and colchicine therapy resulted in complete resolution of the rash, although he continued to have high titres of MPO positive ANCA.

Conclusion

Sweet syndrome is a rare adverse reaction to azathioprine but has also been reported to occur in association with ANCA vasculitis. The temporal association with azathioprine in our case and the relatively rapid resolution of the skin vasculitis upon its withdrawal suggested a primarily drug-induced reaction rather than an associated feature of ANCA vasculitis.

Stress and Disease Onset in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

To explore the potential contribution of stress as a trigger for disease onset in patients with antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV).

METHODS

53 AAV and 85 rheumatoid arthritis (RA) patients as well as 53 healthy controls (HC) were thoroughly asked for the number and impact of stressful life events, coping strategies, and available social support 12 months prior to disease onset. Anxiety, depression, personality dimensions, insomnia, and fatigue were also determined.

RESULTS

AAV patients reported higher scoring of the impact of stressful life events compared to the RA and HC group prior to disease onset (2.8 ± 3.1 vs 1.8 ± 2.1 vs 1.7 ± 2.3, p-values: 0.047 and 0.053, respectively). While the number of reported stressful events was found to be significantly higher in AAV vs RA patients but not HC, certain coping strategies and social support features were more commonly implemented by AAV patients compared to HC, but not RA patients. As far as personality and other psychosocial characteristics, AAV patients displayed significantly higher psychoticism traits compared to RA, with no other differences being detected between AAV patients and both RA and HC. After adjusting for potential cofounders, scoring of the impact of stressful life events >3 was independently associated with AAV development compared to both RA and HC [ORs (95% CI): 4.6 (1.6-13.4) and 4.4 (1.0-19.0), respectively].

CONCLUSION

The perceived impact of stressful life events prior to disease onset emerged as a contributing factor for AAV development.

Therapy and prognosis of ANCA-associated vasculitis from the clinical nephrologist's perspective

This paper reviews the recently published scientific information regarding ANCA-associated vasculitis (AAV), aiming to highlight the most important data from the clinical nephrologists' perspective. The classification, pathomechanism, recent achievements of the treatment, short-term and long-term outcomes of the disease, and the difficulties nephrologists face when taking care for patients with AAV are summarized. There has been significant progress in the understanding of the genetic and pathologic background of the disease in the last years, and results of histological studies guide us to predict long-term renal function. Findings of several multicentered trials with reasonable number of participants provide comparison of the efficacy and safety of different remission induction and maintenance therapies, and evaluate recently introduced immunosuppressive agents. Although the clinical outcome of patients with AAV has improved significantly since modern immunosuppressive drugs are available, the treatment-related complications still contribute to the morbidity and mortality. To improve the survival and quality of life of patients with AAV further, knowledge of the predictors of relapse, end-stage kidney disease, and mortality, also prevention of infections and other treatment-related adverse events are important. The eligibility for renal transplantation and the option for successful pregnancies for young women are also important factors which influence the patients' quality of life. In order to provide favorable outcome, the clinicians need to establish personalized treatment strategies to optimize the intensity and minimize the toxicity of the immunosuppressive therapy.

Fatal pulmonary complication during induction therapy in a patient with ANCA-associated vasculitis

ANCA-associated vasculitis (AAV) is an inflammatory systemic disorder affecting small to medium sized vessels and likely leading to any organ dysfunction. Adequate treatment is important to avoid mortality or severe organ damage. In most cases initial treatment (induction therapy) allows to achieve remission. Induction therapy leads to immunosuppression and may cause severe infections. However, in vasculitis patients even an intensive immunosuppressive therapy is rarely complicated by an invasive fungal infection. We present a case in a 29-year old male patient with newly diagnosed AAV. He suffered a fatal pulmonary complication of the induction immunosuppressive treatment. Pathological (infectious) changes in the lungs were misinterpreted as progression of the vasculitis and he died due to disseminated angioinvasive aspergillosis. A clinical course, imaging and histopathology of this case are described and discussed.

Familial vasculitides: granulomatosis with polyangitis and microscopic polyangitis in two brothers with differing anti-neutrophil cytoplasm antibody specificity

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a group of rare autoimmune diseases. Although the aetiology of AAV is uncertain, it is likely that genetic and environmental factors contribute. We report the unusual case of two brothers presenting with AAV with differing clinical pictures and differing ANCA specificity. There is a recently identified difference in genetic risk factors associated with ANCA specificity, making it surprising that first-degree relatives develop AAV with differing clinical and serological features. Our report illustrates the complex aetiology of AAV and suggests that further research on the interaction of genetic and environmental factors is needed.

A physician survey reveals differences in management of idiopathic pulmonary hemosiderosis

BACKGROUND

Idiopathic pulmonary hemosiderosis (IPH) is a rare disorder of unknown etiology characterized by chronic pulmonary hemorrhage and presents with a triad of anemia, hemoptysis and pulmonary infiltrates. IPH is a diagnosis of exclusion with a variable and disparate clinical course. Despite existing therapies, few children achieve full remission while others have recurrent hemorrhage, progressive lung damage, and premature death.

METHODS

We surveyed physicians who care for patients with IPH via a web-based survey to assess the most common practices. 88 providers responded, caring for 274 IPH patients from five continents.

RESULTS

63.3 % of respondents had patients that were initially misdiagnosed with anemia (60.0 %) or gastrointestinal bleed (18.2 %). Respondents varied in diagnostic tools used for evaluation. The key difference was in the use of lung biopsy (51.9 %) for diagnosis. Common medications respondents used for treatment at initial presentation and chronic maintenance therapy were corticosteroids (98.7 and 84.0 %, initial and chronic therapy respectively), hydroxychloroquine (33.3 and 64.0 %), azathioprine (8.0 and 37.3 %), and cyclophosphamide (4.0 and 16.0 %). There was agreement on the use of corticosteroids for exacerbation amongst all respondents. Reported deaths before adulthood occurred in 7.3 % of patients. We conclude that there were common features and specific variations in physician management of IPH. Respondents were divided on whether to perform lung biopsy for diagnosis.

CONCLUSION

Despite the availability of various immunomodulators, corticosteroids remained the primary therapy. We speculate that the standardization of care for diffuse alveolar hemorrhage will improve patient outcomes.

Necrotizing and crescentic glomerulonephritis presenting with preserved renal function in patients with underlying multisystem autoimmune disease: a retrospective case series

Objective. Necrotizing and crescentic GN usually presents with rapidly declining renal function, often in association with multisystem autoimmune disease, with a poor outcome if left untreated. We aimed to describe the features of patients who have presented with these histopathological findings but minimal disturbance of renal function.

Methods. We conducted a retrospective review (1995–2011) of all adult patients with native renal biopsy–proven necrotizing or crescentic GN and normal serum creatinine (<120 μmol/l) at our centre.

Results. Thirty-eight patients were identified. The median creatinine at presentation was 84 μmol/l and the median proportion of glomeruli affected by necrosis or crescents was 32%. Clinicopathological diagnoses were ANCA-associated GN (74%), LN (18%), anti-GBM disease (5%) and HScP (3%). Only 18% of cases had pre-existing diagnoses of underlying multisystem autoimmune disease, although the majority (89%) had extra-renal manifestations accompanying the renal diagnosis. All patients received immunosuppression and most had good long-term renal outcomes (median duration of follow-up 50 months), although two progressed to end-stage renal disease within 3 years. We estimate that renal biopsy had an important influence on treatment decisions in 82% of cases.

Conclusion. Necrotizing and crescentic GN may present in patients with no or only minor disturbance of renal function. This often occurs in patients with underlying systemic autoimmune disease; early referral for biopsy may affect management and improve long-term outcomes in these cases.

Long-term outcome of anti-neutrophil cytoplasm antibody-associated glomerulonephritis: evaluation of the international histological classification and other prognostic factors

BACKGROUND

Anti-neutrophil cytoplasm antibody (ANCA) associated vasculitis with renal involvement requires treatment with potentially toxic drugs to reduce morbidity and mortality, and there is a major challenge to determine clinical and histological features predictive of renal prognosis. The aim of our study was to evaluate the use of the 2010 international histological classification for ANCA-associated glomerulonephritis (AAGN) as a predictor of renal outcome when used in conjunction with other prognostic factors.

METHODS

One hundred and four patients with AAGN treated at our centre were included: 23 were classified as focal, 26 as crescentic, 48 as mixed and 7 as sclerotic. Renal outcomes were based on estimated glomerular filtration rate (eGFR) at 1 and 5 years, and on renal survival.

RESULTS

By univariate analysis, patients in the focal class had the best renal outcome, those in the sclerotic class the worst outcome, and those in the mixed and crescentic classes had intermediate renal survival. There was no significant difference in outcome between the mixed and crescentic classes. In multivariate models, histological class did not improve model fit or associate with renal outcome after adjusting for established prognostic factors. Lower percentage of normal glomeruli, greater degree of tubular atrophy (TA), MPO-ANCA positivity, increasing age and lower starting eGFR, all correlated with poorer renal outcomes.

CONCLUSIONS

We conclude that, in our cohort of patients, the international histological classification is predictive of renal outcome in AAGN, but did not appear to be additionally informative over other established prognostic factors in multivariate analysis. However, it may be of value to combine the current histological classification with other established parameters, such as TA and percentage normal glomeruli.

Complications of long-term therapy for ANCA-associated systemic vasculitis

The antineutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitides (AASVs) include granulomatosis with polyangiitis and microscopic polyangiitis. These conditions are characterized by small-vessel inflammation and necrosis, predominantly in pulmonary and renal vascular beds. Untreated AASV has a poor prognosis, although the advent of effective immunosuppressive therapy (the mainstay of which remains cyclophosphamide with high-dose corticosteroids) has markedly improved patients' survival (78% at 5 years). Patients with AASV, however, continue to have an increased mortality compared to the general population. Mortality is greatest in the first year after diagnosis and remains consistently elevated in subsequent years. Patients with AASV also experience increased rates of infections, malignancies and cardiovascular events as compared to the general population. Current treatments for AASV, although effective in controlling the aggressive systemic disease, incur substantial long-term toxic effects. Long-term immunosuppressive therapy also has notable deleterious effects on bone health and fertility. The long-term safety profiles of biological therapies (such as rituximab) are yet to be evaluated in patients with AASV, but represent a promising treatment option. The challenge for the future is to develop specific therapies with improved safety profiles that can cure these diseases.

Elevated soluble Flt1 inhibits endothelial repair in PR3-ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis exhibits endothelial damage, but the capacity for vessel repair in this disorder is not well understood. Here, we observed a marked increase in serum levels of soluble Flt1 (sFlt1), a potent inhibitor of vascular endothelial growth factor, in patients with active ANCA-associated vasculitis compared with patients during remission and other controls. Serum levels of sFlt1 correlated with C5a, an anaphylatoxin released after complement activation. Serum from patients with acute ANCA-associated vasculitis disrupted blood flow in the chicken chorioallantoic membrane assay, suggesting an antiangiogenic effect. Preincubation with excess human vascular endothelial growth factor prevented this effect. Anti-proteinase-3 (PR3) mAb and serum containing PR3-ANCA from patients with active vasculitis both induced a significant and sustained release of sFlt1 from monocytes, whereas anti-myeloperoxidase (MPO) mAb or polyclonal antibodies did not. However, the serum containing polyclonal PR3-ANCA did not induce release of sFlt1 from cultured human umbilical vein endothelial cells. In summary, these data suggest that anti-PR3 antibodies, and to a much lesser extent anti-MPO antibodies, increase sFlt1 during acute ANCA-associated vasculitis, leading to an antiangiogenic state that hinders endothelial repair.