TY - JOUR T1 - Increased Expression of Phospholipid Scramblase 1 in Monocytes from Patients with Systemic Lupus Erythematosus JF - The Journal of Rheumatology JO - J Rheumatol DO - 10.3899/jrheum.091420 SP - jrheum.091420 AU - Eriko Suzuki AU - Olga Amengual AU - Tatsuya Atsumi AU - Kenji Oku AU - Toko Hashimoto AU - Hiroshi Kataoka AU - Tetsuya Horita AU - Shinsuke Yasuda AU - Masahiro Ieko AU - Kazuaki Fukushima AU - Takao Koike Y1 - 2010/06/01 UR - http://www.jrheum.org/content/early/2010/05/27/jrheum.091420.abstract N2 - Objective A high incidence of thromboembolic events has been reported in patients with systemic lupus erythematosus (SLE). Phosphatidylserine (PS) is normally sequestered in the inner leaflet of cell membranes. Externalization of PS during cell activation is mediated by phospholipid scramblase 1 (PLSCR1) and has a central role in promoting blood coagulation. We investigated the underlying pathogenic status of thrombophilia in SLE by analyzing PLSCR1 expression on monocytes from patients with SLE. Methods Sixty patients with SLE were evaluated. Twenty-three patients had antiphospholipid syndrome (APS/SLE). Plasma D-dimer levels were measured as a marker of fibrin turnover. The cDNA encoding human PLSCR1 was cloned from the total RNA extract from monocytes, and independent clones were sequenced. PLSCR1 mRNA expression in CD14+ cells was determined by real-time polymerase chain reaction. PS exposure on CD14+ cell surface was analyzed by flow cytometry. Results Elevated D-dimer levels were found in plasma from SLE patients. Three splice variants of PLSCR1 mRNA were identified in all subjects, and levels of full-length PLSCR1 mRNA were significantly increased in SLE compared to healthy controls (2.9 ± 1.5 vs 1.3 ± 0.4, respectively; p < 0.0001). Flow-cytometry analysis showed relative enhancement of PS exposure in the surface of CD14+ cells in SLE patients compared to healthy controls. Conclusion Novel PLSCR1 splice variants were identified. Monocytes in SLE patients had enhanced PLSCR1 mRNA expression, as well as increased fibrin turnover and cell-surface PS exposure, indicating that PLSCR1 may, in part, contribute to the prothrombotic tendency in SLE. ER -