P136 The effects of LY294002, the phosphoinositide 3-kinase inhibitor, on neutrophil apoptosis in patients with rheumatoid arthritis and collagen-induced arthritis in mice
Authors: X Huang, T Li, S Zheng, W Deng, Y Huang, Z Huang, Q Huang, Z Huang
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Career situation of first and presenting author</h3> Young investigator. <h3>Introduction</h3> Neutrophils act as a first line in host defense, they also play important roles on acute and chronic inflammation. Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by persistent joint inflammation.<sup>1</sup> Previous studies have shown that delayed apoptosis of neutrophils correlated with the pathogenesis of RA.<sup>2</sup> <h3>Objectives</h3> The aim of this study was to investigate the effects of LY294002, the phosphoinositide 3-kinase(PI3K) inhibitor, on neutrophil apoptosis in RA patients and collagen-induced arthritis (CIA) in mice. <h3>Methods</h3> The peripheral blood from untreated RA patients who satisfy the 1987 ACR classification criteria for RA (n=20) and healthy volunteers (HC) (n=10) were used to isolate neutrophils by density gradient centrifugation. The neutrophils were cultured with or without LY294002 <i>in vitro</i> for 18 hour. The rate of neutrophils apoptosis were analyzed by flow cytometry. The intracellular protein levels of PI3K-Akt pathway in neutrophils were measured by Western blot. CIA mice were treated with vehicle or LY294002, and the incidence, arthritis score, histological assessment as well as the apoptosis rate of neutrophils from peripheral blood and marrow were analyzed. <h3>Results</h3> The peripheral blood neutrophils apoptosis delayed in RA patients as compared with neutrophils from HC. As compare with the HC, the expression of phosphorylation PI3K(p-PI3K) and p-Akt were increased in RA patients. LY294002 could significantly promote neutrophils apoptosis in peripheral blood from RA patients. LY294002 blocked the activation of PI3K-Akt and inhibited the expression of p-Akt. Moreover, LY294002 treatment delayed the onset, reduced the severity of arthritis in CIA mice. We also found that neutrophils from both peripheral blood and bone marrow delayed apoptosis in CIA mice as compared with the control group, and LY294002 treatment facilitated the neutrophil apoptosis from peripheral blood and marrow in CIA mice. <h3>Conclusions</h3> This data suggested that delayed apoptosis of neutrophils, which might through the activation of PI3K-Akt pathway, played an important role in the development of RA. LY294002 could delay the onset and reduce the severity of arthritis in CIA mice through the promotion of neutrophils apoptosis. It might open a new door to the future clinical treatment of RA. <h3>References</h3> McInnes IB, Schett G. The pathogenesis of rheumatoid arthritis. <i>N Engl J Med</i> 2011;365(23):2205–19. Wright HL, Moots RJ, Edwards SW. The multifactorial role of neutrophils in rheumatoid arthritis. <i>Nat Rev Rheumatol</i> 2014;10(10):593–601. <h3>Acknowledgements</h3> This work was supported by Youth Science Foundation of Guangdong Second Provincial General Hospital (No. YQ2016-002). <h3>Disclosure of Interest</h3> None declared.