Treatment of Autoimmune Diseases with Therapeutic Antibodies: Lessons Learned from PID Patients Allow for Stratification of the Infection Risk

Over the years, a wide variety of therapeutic antibodies has been successfully introduced in the autoimmunology clinic and many more are on the edge to follow. Many of these treatments address either a pathogenic circulating molecule or a cell-bound molecule. Whereas the former target results in neutralization of the soluble factor, the latter target either inhibits cellular function or induces selective cell death. If this targeted molecule or cell is part of the immune system, this therapy evokes a state of immunodeficiency. Knowing the exact function of the respective components enables the risk stratification for possible infectious complications in patients treated with biologics. Much of the understanding of the function of immune cells and their associated molecules, in relation to redundancy in the immune system, is derived from studies in knockout mice. However, as mice are not men in terms of their life-expectancy, their infection exposure, or the composition of their immune system, the most useful knowledge for estimating the consequence of therapeutic intervention on immune competence comes from monitoring patients. In the current chapter, we focus on patients with a primary immunodeficiency (PID) because they provide us with a unique perspective to estimate the redundancy of a certain genetic defect for overall immune competence. These patients have inborn errors of the immune system that, in general, are due to single gene defects. Depending on the immunological pathway that is defective, patients can present with different types of (opportunistic) infectious diseases, as well as other clinical manifestations. Based on selected examples, we focus in this chapter on finding parallels in the infectious risk of autoimmune patients treated with biologics and PID patients with a defect in the immunological pathway that is affected by the respective biologic. The goal is to learn from the (dis)similarities between both patient populations in terms of safety profiles of biologic treatments

Maintaining remission in patients with granulomatosis with polyangiitis or microscopic polyangiitis:the role of ANCA

Introduction: Granulomatosis with Polyangiitis (GPA; formerly Wegener's) and Microscopic Polyangiitis (MPA) are inflammatory disease entities affecting small to medium vessels. They are characterized by the presence of anti-neutrophil cytoplasmic antibodies (ANCA) and are frequently grouped together with Eosinophilic Granulomatosis with Polyangiitis (EGPA; formerly Churg Strauss Syndrome) under the term ANCA-associated Vasculitis (AAV). Due to effective immunosuppressive therapy that was introduced more than 45 years ago, AAV has become a chronic disease in which relapses occur frequently during maintenance treatment or later on after all immunosuppressive therapy is stopped. Since relapses are associated with morbidity and mortality, early detection and prevention of relapses is of great importance. Areas covered: This review focuses on the potential strategies to guide maintenance therapy in patients with GPA or MPA, with an emphasis on patient classifications and the role of serial ANCA measurements. Expert opinion: Risk factors for relapses, e.g., genetic background of the patient, have been studied during the last three decades. Only few of these risk factors directly influence the management of patients. One potentially important factor that may influence therapeutic decisions in AAV patients is serial measurement of ANCA. Recently, it became clear that serial ANCA measurement is an attractive approach in AAV patients with (a history of) capillaritis, e.g., renal involvement or alveolar haemorrhage, but not in patients with more limited disease. Whether ANCA rises can be used to guide therapy and - hence- to prevent relapses has been a great debate during the last three decades. At present, we conclude that small studies do support such an approach but that these findings require further validation in larger randomized clinical trials

B-Cell Analysis for Monitoring Patients Undergoing B-Cell Depletion for the Treatment of Autoimmune Diseases

B-cell depleting therapy is increasingly used in the treatment of many distinct autoimmune diseases. This not only involves remission induction therapy, but also maintenance therapy. In this respect, it is of importance to monitor composition of the B-cell compartment in the peripheral blood. This can be performed at the time of initiation of the therapy, especially in those cases in which the expected clinical effect is not achieved. If B-cells are absent, B-cell depletion may not be the best treatment option; if B-cells are present, the efficacy may be hampered by neutralizing antibodies. For monitoring B-cell recovery it is important not to just enumerate B-cells, but to also phenotype the B-cells. A phenotype of IgD-CD27++CD38++ indicates the presence of circulating plasmablasts that lack CD20 and which are therefore not sensitive for B-cell depletion with anti-CD20 biologicals. A phenotype of IgD+CD27-CD38++ on the other hand, indicates recovery from the bone marrow with transitional B-cells. This chapter will focus on B-cell analyses by flow cytometry

Anti-PLA2R Antibodies as a Prognostic Factor in PLA2R-Related Membranous Nephropathy

Background: The natural course of idiopathic membranous nephropathy (MN) varies, as it is known through favorable outcomes in most patients. However, one third of patients with idiopathic MN will slowly progress to end-stage renal disease (ESRD). To prevent disease progression, patients at high risk to develop ESRD are treated with immunosuppressive agents. Therefore, a correct selection of patients who need immunosuppressive treatment is important. Methods: Here, we evaluated the prognostic value of anti-phospholipase A2 receptor 1 antibody (anti-PLA2R) levels regarding clinical outcome in a well-defined cohort of 73 PLA2R-related MN patients with long-term follow-up. At baseline, patients were subdivided into patients with either low or high antibody levels based on ELISA testing. Results: Spontaneous remission rates were highest among patients with low anti-PLA2R levels (79%; hazard ratio 2.72 (95% CI 1.22-6.08), p = 0.02) after a median follow-up of 2.9 (95% CI 0.8-5.0, p <0.001) years, whereas high anti-PLA2R levels were associated with persistent proteinuria (p = 0.04) and/or the need for immunosuppressive therapy (p <0.001). Renal survival rates were 97% at 5 years, 93% at 10 years, and 89% at 15 years; however, this was not different between the anti-PLA2R groups. ESRD occurred significantly faster in patients with severe proteinuria as compared to patients with either mild (p = 0.02) or moderate proteinuria (p = 0.05). Conclusions: Low anti-PLA2R levels may predict spontaneous remissions in patients with PLA2R-related MN. Therefore, we suggest that quantification of anti-PLA2R is of value to monitor these patients

Seasonal Influence on the Risk of Relapse at a Rise of Antineutrophil Cytoplasmic Antibodies in Vasculitis Patients with Renal Involvement

Objective. The objective of this study was to identify risk factors for a relapse at the time of an increase in antineutrophil cytoplasmic antibodies (ANCA) in patients with renal ANCA-associated vasculitis (AAV).Methods. All patients between January 2000 and November 2011 with renal AAV having an ANCA rise during remission were included. Differences in time to relapse since the ANCA rise were assessed using a Cox regression model. The level of 25-hydroxy Vitamin D (25(OH) D) was assessed at the ANCA rise and at a subsequent relapse or time-matched during remission.Results. Sixty patients had an ANCA rise, of whom 36 patients relapsed. Three risk factors were associated with a relapse at the time of the ANCA increase: previous disease activity not treated with cyclophosphamide or rituximab (HR 3.48, 95% CI 1.60-7.59), an ANCA rise during the fall season (HR 4.37, 95% CI 1.60-11.90), and an extended ANCA rise (HR 3.57, 95% CI 1.50-8.48). Levels of 25(OH) D significantly decreased during followup in relapsing patients, but not in patients who remained in remission (difference -6.3 +/- 14.4, p = 0.017 vs 2.7 +/- 16.3, p = 0.430).Conclusion. ANCA rises occurring during the fall season are more frequently followed by a relapse than ANCA rises occurring during other seasons. Although it is tempting to speculate that decreasing Vitamin D levels following the ANCA rise can be held responsible for the subsequent relapse, this remains to be determined.</p