Neutrophil Membrane Expression of Proteinase 3 (PR3) Is Related to Relapse in PR3-ANCA-Associated Vasculitis

Abstract

Abstract. Wegener granulomatosis (WG) is strongly associated with the presence of antineutrophil cytoplasm autoantibodies (ANCA) with specificity for proteinase 3 (PR3). Relapses of WG are frequently preceded by a rise of autoantibody titer and PR3-ANCA are able to activate primed neutrophils in vitro. Except being stored intracellularly and translocated to the cell surface upon neutrophil stimulation, PR3 can also be detected on the surface of non-stimulated neutrophils (membrane PR3 or mPR3), with an interindividual variability in percentages of mPR3 Ϫ -positive cells and level of mPR3 expression. This study began with the hypothesis that the presence of PR3 on the surface of non-stimulated neutrophils enables interaction with PR3-ANCA and influences clinical manifestations of the disease. It analyzed mPR3 expression on neutrophils of 89 WG patients in complete remission and 72 healthy controls to evaluate whether the presence of PR3 on the surface of resting neutrophils is related to clinical manifestations of WG and/or to the susceptibility to develop relapses. The number of patients with a bimodal mPR3 expression on resting neutrophils did not differ between patients and controls. However, in WG patients, an increased percentage of mPR3 ϩ neutrophils and an elevated level of mPR3 expression compared with healthy individuals (P ϭ 0.037) were found. Within the group of WG patients, an elevated level of mPR3 expression was significantly associated with an increased risk for relapse (P ϭ 0.021) and with an increased relapse rate (P ϭ 0.011), but not with the disease extent or particular manifestations at diagnosis or at relapse. These data support the hypothesis that PR3 expression on the membrane of neutrophils plays a role in the pathophysiology of PR3-ANCA associated vasculitis.Wegener granulomatosis (WG) is a systemic disease characterized by necrotizing inflammation of the respiratory tract, vasculitis, and pauci-immune glomerulonephritis (1). WG is strongly associated with the presence of antineutrophil cytoplasm autoantibodies (ANCA) with specificity for proteinase 3 (PR3) (2-4). Although the role of these autoantibodies has not been fully established yet, there is increasing evidence that PR3-ANCA are involved in the pathogenesis of WG. Remarkably, relapses of WG are frequently preceded by a rise of PR3-ANCA (5,6).PR3 is a serine proteinase stored in azurophil granules of polymorphonuclear neutrophils (7,8). It has also been shown to localize in specific granules and secretory vesicles (9). In vitro, after priming with tumor necrosis factor-␣ (TNF␣) PR3 is translocated to the cell surface, where it becomes accessible for interaction with PR3-ANCA (10). Cross-linking of PR3 and Fc␥ receptors on the surface of primed neutrophils by PR3-ANCA induces neutrophil activation that results in the release of reactive oxygen species and proteolytic enzymes (11)(12)(13)(14). Moreover, ANCA-activated neutrophils have been shown to be cytotoxic against vascular endothelium (15).Recently, it has been found that in som...

Membrane Proteinase 3 Expression in Patients with Wegener’s Granulomatosis and in Human Hematopoietic Stem Cell–Derived Neutrophils

“…This finding has not yet been reported. These data extend those of an earlier report (15). Because mPR3 expression seems pivotal and genetically determined, we next differentiated human CD34 ϩ progenitor cells to neutrophils.…”

“…On the basis of this mPR3 expression pattern, neutrophils can be divided into an mPR3 high and an mPR3 low subset. This bimodal expression pattern is stable in a given individual, does not change with cell activation, and is genetically determined (15)(16)(17). Other investigators and our own group demonstrated that a large percentage of mPR3 high neutrophils provides a risk factor for WG (15)(16)(17).…”

“…This bimodal expression pattern is stable in a given individual, does not change with cell activation, and is genetically determined (15)(16)(17). Other investigators and our own group demonstrated that a large percentage of mPR3 high neutrophils provides a risk factor for WG (15)(16)(17). We investigated the correlation between a large mPR3 high subset and the clinical and laboratory disease manifestation in a cohort of 81 WG patients.…”

“…Although the amount of mPR3 changes with activation, the individual percentage of mPR3 high neutrophils is stable during a person's lifetime and does not change appreciably with activation status or the neutrophil's age (14 -16). A high percentage of mPR3 high neutrophils was a risk factor for vasculitis, was associated with relapse in a Dutch cohort of patients wit WG, and resulted in stronger neutrophil activation by PR3 ANCA in vitro in earlier studies (15)(16)(17)(18). Thus, a detailed understanding of mechanisms that control this dual mPR3 expression pattern is important.…”

Identification of Functional and Expression Polymorphisms Associated With Risk for Antineutrophil Cytoplasmic Autoantibody–Associated Vasculitis

“…This association was limited to the GPA and PR3‐ANCA subsets (Table 2), consistent with the pathophysiologic relevance of the PRTN3 ‐encoded PR3 serine protease to these phenotypes 17.…”