ANCA-associated vasculitis: new options beyond steroids and cytotoxic drugs

Anti-neutrophil cytoplasmic antibodies-associated vasculitis: a guide and case study

Vasculitis is a relatively rare and poorly understood condition causing inflammation of the blood vessels, which in turn can affect a patient's respiratory and renal systems. In some cases, ocular involvement can cause loss of sight and hearing loss may also be a red flag for vasculitis, which, if not treated early, can cause complete hearing loss. Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) is a group comprising granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis (EGP). AAV is fatal if untreated and as increased risk escalates with age, coupled with a decline in renal function, these are the principal predictors of poor outcome. Vital roles for nursing vasculitis patients lie in managing inflammation and pain, as these distressing symptoms are prevalent in the disease. Because of the multiple complications that can occur with vasculitis, treatment-related information is a high priority for these patients. As nurses are well placed to deliver information, value lies in their role in reducing the negative impacts on treatment regimens and compliance that accompany patients' poor insight into their condition.

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.

Semaphorin 4D inhibits neutrophil activation and is involved in the pathogenesis of neutrophil-mediated autoimmune vasculitis

OBJECTIVES

Inappropriate activation of neutrophils plays a pathological role in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The aim of this study was to investigate the functions of semaphorin 4D (SEMA4D) in regulation of neutrophil activation, and its involvement in AAV pathogenesis.

METHODS

Serum levels of soluble SEMA4D were evaluated by ELISA. Blood cell-surface expression of membrane SEMA4D was evaluated by flow cytometry. To determine the functional interactions between neutrophil membrane SEMA4D and endothelial plexin B2, wild-type and SEMA4D-/- mice neutrophils were cultured with an endothelial cell line (MS1) stained with SYTOX green, and subjected to neutrophil extracellular trap (NET) formation assays. The efficacy of treating human neutrophils with recombinant plexin B2 was assessed by measuring the kinetic oxidative burst and NET formation assays.

RESULTS

Serum levels of soluble SEMA4D were elevated in patients with AAV and correlated with disease activity scores. Cell-surface expression of SEMA4D was downregulated in neutrophils from patients with AAV, a consequence of proteolytic cleavage of membrane SEMA4D. Soluble SEMA4D exerted pro-inflammatory effects on endothelial cells. Membranous SEMA4D on neutrophils bound to plexin B2 on endothelial cells, and this interaction decreased NET formation. Recombinant plexin B2 suppressed neutrophil Rac1 activation through SEMA4D's intracellular domain, and inhibited pathogen-induced or ANCA-induced oxidative burst and NET formation.

CONCLUSIONS

Neutrophil surface SEMA4D functions as a negative regulator of neutrophil activation. Proteolytic cleavage of SEMA4D as observed in patients with AAV may amplify neutrophil-mediated inflammatory responses. SEMA4D is a promising biomarker and potential therapeutic target for AAV.

[Medium and large vessel vasculitis]

Vasculitis comprises a broad group of syndromes characterized by inflammation and necrosis on the walls of blood vessels, resulting in narrowing or occlusion of the lumen. The distribution of involved blood vessel varies considerably and serves as the basis for one classification of vasculitic syndromes: large vessels (Takayasu arteritis, giant cell arteritis); medium and small muscular arteries (polyarteritis nodosa, Churg-Strauss syndrome, Wegener's granulomatosis, vasculitis in rheumatic diseases); and small vessels ("hypersensitivity" vasculitis, Henoch-Schonlein purpura, microscopic polyangiitis, cryoglobulinemia). This article reviews medium and large vessel vasculitis and current treatment options; it also presents a comprehensive approach to diagnosing and treating patients with suspected cutaneous vasculitis.

Expression profiling of PBMC-based diagnostic gene markers isolated from vasculitis patients

Vasculitis (angiitis) is a systemic autoimmune disease that often causes fatal symptoms. We aimed to isolate cDNA markers that would be useful for diagnosing not only vasculitis but also other autoimmune diseases. For this purpose, we used stepwise subtractive hybridization and cDNA microarray analyses to comprehensively isolate the genes whose expressions are augmented in peripheral blood mononuclear cells (PBMCs) pooled from vasculitis patients. Subsequently, we used quantitative real-time polymerase chain reaction (qRT–PCR) to examine the mRNA levels of each candidate gene in individual patients. These analyses indicated that seven genes exhibit remarkably augmented expression in many vasculitis patients. Of these genes, we analyzed G0/G1 switch gene 2 (G0S2) further because G0S2 expression is also enhanced in the PBMCs of patients with systemic lupus erythematodes (SLE). We generated G0S2 transgenic mice that ubiquitously overexpress human G0S2. Although we did not observe any obvious vasculitis-related histopathologic findings in these mice, these mice are unhealthy as they produce only few offspring and showed elevated serum levels of two autoimmunity-related antibodies, anti-nuclear antibody, and anti-double strand DNA antibody. Thus, our large-scale gene profiling study may help finding sensitive and specific DNA markers for diagnosing autoimmune diseases including vasculitis and SLE.