Increased release of myeloperoxidase in vitro from neutrophils of patients with myeloperoxidase‐specific anti‐neutrophil cytoplasmic antibody (MPO‐ANCA) related glomerulonephritis

Abstract

Summary: In order to elucidate the role of neutrophils in the pathogenesis of MPO‐specific anti‐neutrophil cytoplasmic antibody (MPO‐ANCA) related glomerulonephritis (GN), MPO release, beta‐glucuronidase (BGL) release, superoxide anion (O2−) production from the neutrophils of patients with MPO‐ANCA related GN were measured. the effect of plasma on MPO release from neutrophils was also studied in patients with MPO‐ANCA related GN. Neutrophils and plasma were obtained from patients with MPO‐ANCA related GN, GN unrelated to MPO‐ANCA and healthy controls. MPO release from the neutrophils of patients with MPO‐ANCA related GN was higher than that of controls significantly. This was also higher than that in patients with GN unrelated to MPG‐ANCA, but this was not statistically significant. Superoxide anion production from neutrophils of patients with MPO‐ANCA related GN was significantly higher than that in patients with GN unrelated MPO‐ANCA, However, BGL release was not significantly different among three groups. Furthermore, MPO release and O2− production increased in parallel with clinical activity of MPO‐ANCA related GN. Neutrophils of patients with MPO‐ANCA related GN showed to be significantly more sensitive to FMLP on MPO release than those in the other two groups. However, plasma from MPO‐ANCA related GN increased the sensitivity to FMLP on MPO release, but not BGL release, in neutrophils obtained from healthy controls, whereas it suppressed MPO release from neutrophils with MPO‐ANCA related GN. This suggests that in patients with MPO‐ANCA related GN MPO can be highly released from activated neutrophils and that the plasma of patients with MPO‐ANCA contains factor(s) which modulate reactivity of neutrophils.

Identification of MPO-positive capillaries of the pleura by immunohistochemistry in MPO-ANCA associated vasculitis

“…It was demonstrated in vitro that the neutrophils, the majority of MPO + cells, in patients with ANCA‐associated vasculitis are activated by MPO‐ANCA and interleukin‐8, thus, inducing them to adhere to the endothelium 7 . With regard to the MPO‐ANCA‐positive endothelium, it was demonstrated that neutrophils in the active phase of MPO‐ANCA‐associated nephritis are apt to release MPO, and that positively‐charged MPO can easily bind to the negatively‐charged endothelium of the glomeruli 8 . Furthermore, the chromatin fibers, so called neutrophil extracellular traps, may be released by ANCA‐stimulated neutrophils that contain MPO 9 …”

“…7 With regard to the MPO-ANCA-positive endothelium, it was demonstrated that neutrophils in the active phase of MPO-ANCA-associated nephritis are apt to release MPO, and that positively-charged MPO can easily bind to the negatively-charged endothelium of the glomeruli. 8 Furthermore, the chromatin fibers, so called neutrophil extracellular traps, may be released by ANCA-stimulated neutrophils that contain MPO. 9 Double staining for MPO and endothelial cell markers in the present study indicated that MPO immunopositivity was frequently identified in CD31 + , CD34 + , or factor 8 + endothelial cells, while MPO immunopositivity was identified in some CD34endothelial cells.…”

Novel missense mutation found in a Japanese patient with myeloperoxidase deficiency

“…To examine the normal formation of azurophil granules, in which MPO is enclosed, BGL release and O 2 À production were assayed. BGL release was elicited by methods described previously (Minoshima et al, 1997). The patient, patient's mother and healthy control showed no difference in BGL and O 2 À production.…”

“…Beta-glucuronidase activity and release was elicited by methods described previously (Minoshima et al, 1997). Cell supernatant and homogenate (40 Al) was treated with 1 mmol/l 4-methylumbelliferyl-beta-D-glucuronide, 0.05% Triton X-100 and 0.1 mol/l sodium acetate buffer (pH 3.5) in 96-well flat bottom plate.…”

AP-VAS 2012 case report: a case of systemic MPO-ANCA-associated vasculitis that demonstrated brain infarction and immunohistochemically MPO-positive capillaries

“…Furthermore, histological documentation of brain in this disease is extremely rare. On the other hand, the etiology of the capillaritis has been postulated to be the release of enzymes including MPO from neutrophils, which are activated by ANCA and cytokines, also known as the ANCA-cytokine sequence theory [4,5]. However, immunohistochemical detection of MPO-positive cells on the capillary has rarely been reported.…”