Elevated neutrophil membrane expression of proteinase 3 is dependent upon CD177 expression

Abstract

SummaryProteinase 3 (PR3) is a major autoantigen in anti-neutrophil cytoplasmic antibodies (ANCA)-associated systemic vasculitis (AASV), and the proportion of neutrophils expressing PR3 on their membrane (mPR3 + ) is increased in AASV. We have shown recently that mPR3 and CD177 are expressed on the same cells in healthy individuals. In this study we try to elucidate mechanisms behind the increased mPR3 expression in AASV and its relationship to CD177. All neutrophils in all individuals were either double-positive or double-negative for mPR3 and CD177. The proportion of double-positive neutrophils was increased significantly in AASV and systemic lupus erythematosus patients. The proportion of mPR3 + /CD177 + cells was not correlated to general inflammation, renal function, age, sex, drug treatment and levels of circulating PR3. AASV patients had normal levels of granulocyte colonystimulating factor and granulocyte-macrophage colony-stimulating factor. Pro-PR3 was found to constitute 10% of circulating PR3 but none of the mPR3. We found increased mRNA levels of both PR3 and CD177 in AASV, but they did not correlate with the proportion of double-positive cells. In cells sorted based on membrane expression, CD177-mRNA was several-fold higher in mPR3 + cells. When exogenous PR3 was added to CD177-transfected U937 cells, only CD177+ cells bound PR3 to their membrane. In conclusion, the increased membrane expression of PR3 found in AASV is not linked directly to circulating PR3 or PR3 gene transcription, but is dependent upon CD177 expression and correlated with the transcription of the CD177 gene.

History, Classification and Pathophysiology of Small Vessel Vasculitis

“…Experiments performed by our group, have shown that the plasma levels of mature PR3 as well as pro-PR3 are elevated in AASV [114,115,116]. It was also observed that mPR3 + neutrophils are more abundant in AASV compared to healthy donors, which agrees with previous studies suggesting that a high percentage of mPR3 + cells may be a risk factor for vasculitis [78,115].…”

“…Our group has demonstrated that the mPR3 + /CD177 + neutrophil subpopulation was larger in AASV patients as compared to healthy controls, which suggests a distinct pathophysiological neutrophil phenotype in AASV [116]. Interestingly, higher CD177-mRNA, but not PR3-mRNA was found to correlate with a higher proportion of mPR3+/CD177+cells, suggesting that overproduction of CD177 could lead to an increase in the proportion of mPR3+/ CD177+neutrophils [116].…”

The Role of Proteinase 3 and Neutrophils in ANCA-Associated Systemic Vasculitis

“…This holds true also during stable remission and shows no relation to general inflammation, medical treatment or decreased renal function (Henshaw, 1994;Ohlsson, 2003). Studies by our group have shown that the levels of plasma PR3, mPR3 and pro-PR3 are all elevated in patients with AASV (Abdgawad, 2010). Also, it was observed that mPR3+ neutrophils are more abundant in AASV compared to healthy donors, which agrees with previous studies suggesting that a high percentage of mPR3+ cells may be a risk factor for vasculitis.…”

“…These PR3-activated DCs stimulate autoreactive Th1-type PR3-specific CD4+T cells. Our group has demonstrated that the mPR3+/CD177+ neutrophil subpopulation was larger in AASV patients as compared to healthy controls, which suggests a distinct pathophysiological basis (Abdgawad, 2010 ). mPR3 and CD177 exhibit a parallel dynamic membrane expression with rapid internalization and re-expression.…”

The neutrophil serine protease PR3 induces shape change of platelets via the Rho/Rho kinase and Ca2+ signaling pathways

“…They all are secreted extracellularly upon neutrophil activation [8], but only PR3 is constitutively expressed on the plasma membranes of a subpopulation of resting neutrophils [9,10]. The levels of plasma PR3, proPR3 and neutrophil membrane PR3 are all elevated in patients with sepsis and AAV [10]. PR3 can enzymatically degrade the major macromolecules of extracellular matrix [8].…”