| Summary: | 碩士 === 國立臺灣大學 === 分子醫學研究所 === 91 === Anti-neutrophil cytoplasmic antibodies (ANCA) are autoantibodies directly against the molecules in the cytoplasmic azophilic granules of human polymorphonuclear neutrophil (PMN) and lysosomes of monocyte such as myeloperoxidase (MPO), and proteinase 3 (PR3), and elastase etc. ANCA have been found in patients with primary small vessel vasculitis (SVV), such as Wegener's granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome. It has been demonstrated that ANCAs may play an important role in the pathogenesis of tissue damage via PMN-activation in patient with ANCA-associated vasculitis. But the molecular mechanism of ANCA-mediated neutrophil activation is not fully understand. In this study, we intend to investigate the affection of ANCAs on function changes of human PMN.
Immunohistochemical stain was used to determine the specificity of the commercially available mouse monoclonal antibody against human myeloperoxidase (MPO-ANCA) and proteinase 3 (PR3-ANCA). We used flow cytometry method to analyze the membrane expression of MPO and PR3 on normal human neutrophils.We compared the effects of the two ANCA antibodies on the neutrophil functions including phagocytosis, apoptosis, glucose uptake, production of IL-8 and soluble TRAIL, and intracellular tyrosine phosphrylation.
We found that LPS and TNF-α could enhance membrane expression of ANCA-antigens MPO and PR3 on neutrophils. Both ANCA antibodies stimulated neutrophils to increase phagocytosis, IL-8 and soluble TRAIL production, and finally lead to PMN apoptosis. The effect of MPO-ANCA was generally greater and rapid than PR3-ANCA. In addition, we find a phosphorylated 47.5 kDa molecules appreared after MPO-ANCA stimulation. Bioenergetically the glucose uptake of PMN was enhanced by MPO-ANCA until 4 h stimulation declined after 24 h reaction.
In conclusion， we found that ANCA can stimulate neutrophil to damage endothelium cells by generation of reactive oxygen species. The increased IL-8 production is an another important factor to amplify the inflammation reaction and finally leads PMN into apoptosis via activation-induced cell death mechanism. We also notice the two ANCA have different PMN-activation potency and intracellular signal transduction mechanism. Undoubtedly, more investigation is needed to confirm it.
|
|---|
