Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis Complicated by Thrombotic Microangiopathy with Posterior Reversible Encephalopathy Syndrome Successfully Treated with Eculizumab: A Case Report

Thrombosis in vasculitis: An updated review of etiology, pathophysiology, and treatment

Introduction

Thromboembolic disease is a complication of many vasculitides. A common observation is that thromboembolic events coincide with the period of vasculitic disease, but the mechanism by which this occurs remains unclear. Inflammatory thrombosis is now recognized as a symptom of arteritis rheumatic, and vasculitides such as Behçet's syndrome (BS), and anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) or giant cell arteritis (GCA). This systematic review aimed to explain recent findings related to etiology, pathophysiology, and treatment methods for BS, AAV, and medium/large-vessel vasculitis.

Methods

A comprehensive literature search on English sources from PubMed, Scopus, MEDLINE, Science Direct, ProQuest, AIM, CINAHIL, and ELDIS databases was used to find the relevant articles and reports. The relevant papers (having full text) were obtained until June 2023. Two independent reviewers screened the titles and abstracts of the obtained articles, and a third arbitrator resolved disputes between the reviewers.

Results and conclusion

It is becoming increasingly clear that certain systemic inflammatory diseases, like vasculitis, are linked to a higher risk of both venous and arterial thrombosis. An increased incidence of thromboembolic disease in AAV has been noted, particularly during times of active disease. Growing evidence supports the use of immunosuppression in the management of venous thrombosis in vasculitis. These patients also have a higher risk of developing ischemic disease.

ANCA-Associated Vasculitis with Systemic Thrombotic Microangiopathy: A Review of Literature

Introduction

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) rarely coexist with systemic thrombotic microangiopathy (TMA).The TMA can be in the form of either hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP). This review explores the clinical characteristics, histopathological findings, treatment options, and outcomes in patients presenting as AAV with coexisting HUS/TTP.

Methods

We conducted a search on the PubMed database and additional searches from January 1998 to September 2022 using the following terms: "ANCA", "Antineutrophil cytoplasmic antibody", "thrombotic thrombocytopenic purpura", "TTP", "thrombotic microangiopathy", "haemolytic uremic syndrome", and "HUS". We excluded articles that described renal-limited TMA. Two authors independently reviewed the full texts and extracted all critical data from the included case reports. Finally, we included 15 cases for this review. Hematological remission and kidney recovery in the form of independence from dialysis was assessed.

Results

The median age of the patients was 61 years and a majority of them were females (66.7%). Myeloperoxidase (MPO)-ANCA positivity (66.67%) was more common than proteinase 3 (PR3)-ANCA positivity (33.33%). All patients had laboratory parameters consistent with systemic TMA (HUS or TTP), and only six (out of 11) cases showed histological features of renal TMA. Ten had crescentic glomerulonephritis, and two had advanced degrees of chronicity in histology. Eighty-six percent of cases had hematological remission, and sixty percent of cases became dialysis-independent after treatment.

Conclusion

In conclusion, kidney outcome was worse in patients who manifested both AAV and systemic TMA. A paucity of literature regarding this diagnostic quandary calls for avid reporting of such cases.

Investigation of Clinical Features and Association between Vascular Endothelial Injury Markers and Cytomegalovirus Infection Associated with Thrombotic Microangiopathy in Patients with Anti-Neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis: Case-Based Research

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) can occasionally trigger thrombotic microangiopathy (TMA). Cytomegalovirus (CMV) may be reactivated during intensive immunosuppressive therapy for AAV and cause TMA. Therefore, we aimed to evaluate the clinical features of and the association between vascular endothelial injury markers and TMA due to CMV in patients with AAV. A 61-year-old female was diagnosed with AAV and severe kidney injury. Immunosuppressive therapy gradually improved her symptoms and laboratory findings. However, 2 weeks after induction therapy initiation, she exhibited altered consciousness, a significant decrease in platelet count, and hemolytic anemia, resulting in a TMA diagnosis. Plasma exchange did not improve TMA findings and routine screening test revealed CMV infection. Ganciclovir injection improved the infection and TMA findings. Consequently, we diagnosed her with CMV-induced TMA. Both AAV and CMV may induce severe vascular endothelial injury, potentially leading to TMA development. CMV-induced TMA should be considered when TMA develops during induction therapy against AAV. Moreover, of the three serum markers of vascular injury-serum sulfatides, soluble thrombomodulin, and pentraxin 3-serum sulfatides may be associated with the development of TMA, and a high level of soluble thrombomodulin may be associated with the development of CMV viremia during the clinical course of AAV.

Evolution of Therapy for ANCA-Associated Vasculitis with Kidney Involvement

ANCA-associated vasculitis (AAV) belongs to a group of small vessel systemic vasculitides characterized by granulomatous and neutrophilic inflammation of various tissues. Patients often have circulating autoantibodies targeting neutrophilic antigens. Although AAV was once associated with severe end-organ damage and extremely high mortality rates, the use of glucocorticoids and cyclophosphamide led to a paradigm change in its treatment. Over the past 20 years, significant progress in understanding the immunopathogenesis of AAV has enabled development of targeted immunotherapies, providing a much better prognosis for patients. This review describes the evolution of treatment of AAV, particularly for patients with kidney involvement.

Low levels of complement factor C3 at diagnosis can predict outcome in antineutrophil antibody associated vasculitis

INTRODUCTION

Experimental data support the involvement of complement in the pathogenesis of antineutrophil antibody associated vasculitis, and clinical studies describe a more severe disease phenotype in patients with antineutrophil antibody associated vasculitis and complement activation. In the present study, we looked for an association between circulating serum complement factor 3 levels at diagnosis and outcomes.

METHODS

One hundred sixty-four patients with antineutrophil antibody associated vasculitis who underwent kidney biopsy at our center during the last 15 years were retrospectively reviewed. Patients were categorized according to their serum complement factor 3 level at diagnosis. Patient and renal survival were compared between those above and below the median serum complement factor 3 at diagnosis.

RESULTS

During the first year, 6 patients died and 53 reached end-stage renal disease. Death or end-stage renal disease at one-year were significantly more common in the low serum complement factor 3 group (44 vs. 29%, p = 0.037). In the multivariable analysis, serum complement factor 3 was the strongest negative outcome predictor (HR, 95%CI 0.118, (0.021-0.670)). The lower the serum complement factor 3 level at baseline, the higher the risk of dialysis and death. The risk was particularly high for both endpoints if the serum complement factor 3 concentration was below 0.9 g/l at baseline.

CONCLUSION

Complement activation at diagnosis may identify a distinct subgroup of patients with antineutrophil antibody associated vasculitis and higher risk for poor outcomes. However, it remains to be proven whether inhibition of serum complement factor 3 is beneficial and safe in the clinical setting.

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.

Posterior reversible encephalopathy syndrome and autoimmunity

Posterior reversible encephalopathy syndrome (PRES) is a clinical syndrome characterized by acute or subacute onset of neurological symptoms (e.g., headache, seizure, confusion, vomiting, and diminished eyesight) and impaired endothelial barrier function of the cerebral circulation that leads to bilateral subcortical vasogenic edema, while exhibiting a "reversible" feature in most cases. Clinically, various predisposing or precipitating conditions have been identified, such as hypertension, autoimmune diseases, renal dysfunction/failure, preeclampsia/eclampsia, post-transplantation conditions, and certain therapeutic agents. Among several putative mechanisms, the immune activation hypothesis prevails, as up to 50% of patients with PRES harbor abnormalities related to autoimmunity, such as concurrent systemic lupus erythematosus. In this Review, we summarize the clinical and laboratory evidence that places PRES in the context of autoimmunity.

The complement system in antineutrophil cytoplasmic antibody-associated vasculitis: pathogenic player and therapeutic target

PURPOSE OF REVIEW

The purpose of this review is to discuss the role of the complement system in the pathogenesis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) as well as the employment of complement inhibitors in AAV treatment.

RECENT FINDINGS

AAV has traditionally been considered a pauci-immune disease until recent findings demonstrated the pathogenic role of the complement system. The complement alternative pathway is crucial in AAV, and C5a seems to be a key molecule for AAV to develop. Avacopan, a C5a-receptor (C5aR) antagonist, proved effective in achieving AAV remission and ameliorating kidney function.

SUMMARY

The increased circulating levels of some complement components - as well as the consumption of others - in patients with AAV suggested a systemic activation of the complement system. Low C3 levels correlate with a more aggressive disease and a worse renal prognosis. In ANCA-associated glomerulonephritis, renal deposits of C3d and properdin, suggestive of local alternative pathway activation, correlate with glomerular crescents and proteinuria. The interaction between C5a and neutrophil triggers alternative pathway activation, suggesting the central role of C5a in AAV pathogenesis. Avacopan, a C5aR inhibitor, showed beneficial effects in AAV and represents a promising therapy to achieve sustained remission and to spare glucocorticoids.

Role of complement activation in anti-neutrophil cytoplasmic antibody-associated glomerulonephritis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune disease characterized by necrotizing inflammation of small or medium vessels, causing ANCA associated glomerulonephritis (AAGN). AAGN is defined as pauci-immune glomerulonephritis with no or little immune deposition; hence, activation of the complement system in AAV was overlooked until recently. However, many studies in mice and humans have revealed a crucial role for complement system activation in the development of AAGN. Circulating and urinary detection of various complement components associated with AP activation, which have been broadly correlated with the clinical activity of AAGN, has been reported and may be useful for predicting renal outcome at the time of diagnosis and setting up personalized treatments. Moreover, recent investigations have suggested the possible contribution of the complement classical or lectin pathway activation in the development of AAGN. Thus, as therapeutic options targeting complement components are making rapid strides, the primary complement pathway involved in AAGN disease progression remains to be elucidated: this will directly impact the development of novel therapeutic strategies with high specificity and reduced side effects. This review summarizes and discusses the most recent evidence on the crucial roles of the complement system in the development of AAGN and possible therapeutic strategies that target complement components for disease management.

Is There a Place for Complement Inhibition with Monoclonal Anti-C5a Antibody Vilobelimab in the Treatment of Patients with ANCA-associated Vasculitis?

Recent studies have implicated the complement system in the pathogenesis of antineutrophil cytoplasmic antibody-associated vasculitis (AAV), prompting the development of novel therapeutic agents to target the complement system accordingly. The pivotal role of complement component C5a, in particular, has been the subject of a number of phase II and phase III clinical trials. Indeed, the US Food and Drug Administration has already approved avacopan, an oral C5a receptor inhibitor, as an adjunct for the treatment of active severe AAV, based on its favourable safety profile and non-inferiority to glucocorticoids (GCs) (at Week 26). The novel monoclonal anti-C5a antibody vilobelimab has also been studied in a phase II trial in patients with AAV (IXchange; ClinicalTrials.gov Identifier: NCT03895801). The results appear promising; in addition to decreased GC toxicity index, a smaller number of treatment-emergent adverse events have been observed in vilobelimab-treated patients. However, the study was not powered statistically to compare the efficacy of vilobelimab to standard GC treatment. This editorial summarizes the study findings and outlines potential future directions.