Update on targeted treatments for ANCA-associated vasculitis

Targeted therapy has revolutionized the management of ANCA-associated vasculitis (AAV) over the last fifteen years. Rituximab, an approved induction and maintenance agent for severe AAV, is no less effective than cyclophosphamide as induction therapy and particularly useful in relapsing or refractory disease, or in women. In patients with relapsing AAV, granulomatosis with polyangiitis or PR3-ANCA, it is more effective than cyclophosphamide. Rituximab maintenance is superior to the conventional immunosuppressive drugs that it replaces. Low-dose preemptive rituximab infusions are recommended every 6months for 18months, followed by re-evaluation to decide whether 4 additional biannual infusions should be administered, balancing the probability of relapse and the risk of serious infections on rituximab. A growing body of experimental and clinical data shows that C5a pathway inhibition is a promising therapeutic option for AAV, which could reduce glucocorticoids needs. Avacopan is a first approved oral C5A receptor antagonist, used when there is a high risk that glucocorticoids will cause serious adverse events. In eosinophilic granulomatosis with polyangiitis, the importance of IL-5 for eosinophil activation and survival led to evaluation and approval of mepolizumab, a humanized monoclonal antibody directed against IL-5. Mepolizumab showed a steroid-sparing effect. Its effectiveness in active vasculitis remains uncertain and is currently being evaluated. Benralizumab targeting the IL-5 receptor was recently shown to be noninferior to mepolizumab. Rituximab has had disappointing results in non-severe active vasculitis and is being evaluated as maintenance therapy. Plasma exchange is not indicated as first-line treatment but remains recommended when creatinine levels exceed 300μmol/L.

Neutrophils in ANCA-associated vasculitis: Mechanisms and implications for management

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of systemic autoimmune diseases, which is typified by inflammatory necrosis predominantly affecting the small vessels and often accompanied by positive ANCA. Clinically, AAV primarily includes microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). It has been found that in AAV pathogenesis, both innate and adaptive immunity are related to neutrophil function mutually. Many proteins, such as myeloperoxidase (MPO) and proteinase 3 (PR3), in neutrophil cytoplasm lead to the production of proteins such as MPO-ANCA and PR3-ANCA by activating adaptive immunity. In addition, through the process of neutrophil extracellular trap (NET) formation, activation of an alternative complement pathway and the respiratory burst can stimulate the neutrophils close to vascular endothelial cells and will participate the vessel inflammation. This review aims to reveal the potential mechanisms regulating the association between the neutrophils and various types of AAVs and to emphasize the results of recent findings on these interactions. Moreover, multiple underlying signaling pathways involved in the regulation of neutrophils during AAV processes have also been discussed. The ultimate goal of this review is to identify novel biomarkers and therapeutic targets for AAV management in the future.

From Kidney to Brain: An Uncommon Severe Relapse of Myeloperoxidase Anti-Neutrophil Cytoplasmic Antibody (MPO-ANCA) Vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of rare autoimmune diseases that affect medium and small blood vessels, with uncommon, variable central nervous system (CNS) involvement. It poses diagnosis challenges due to the limited accuracy of conventional imaging and vast differential diagnosis. We describe the case of a 76-year-old man with a previously diagnosed myeloperoxidase (MPO)-positive AAV with exclusive renal involvement. The patient presented to our emergency department (ED) with sudden-onset weakness of the right side of the body, difficulty speaking, fever, and a history of progressive cognitive impairment in the previous three months (loss of memory, time and space disorientation, acalculia). Brain imaging showed multiple acute and subacute ischemic lesions, suggesting CNS vasculitic involvement. The patient was treated with methylprednisolone pulses, followed by rituximab, with motor and cognitive improvement. Timely diagnosis and adequate treatment of AAV as a cause for new-onset neurological symptoms are crucial to improve outcomes. Otherwise, a higher risk of relapse remains, and extensive neurological deficits may become permanent. Evidence regarding the best treatment options in these patients is scarce and case reports provide further data on this topic.