Role of TLR-4 in anti-[beta]2-glycoprotein I-induced activation of peritoneal macrophages and vascular endothelial cells in mice

• Published in: Molecular medicine reports Vol. 19; no. 5; p. 4353
• Main Authors: Wang, Meiyun, Kong, Xiangmin, Xie, Yachao, He, Chao, Wang, Ting, Zhou, Hong
• Format: Journal Article
• Language: English
• Published: Spandidos Publications 01.05.2019
• Subjects: Antibodies; Antiphospholipid antibodies; Antiphospholipid syndrome; Care and treatment; Cellular signal transduction; Cytokines; Endothelium; Immunoglobulin G; Immunoglobulins; Inflammation; Interleukins; Macrophages; Messenger RNA; Mitogens; Morbidity; Necrosis; Phospholipids; Pregnancy; Protein kinases; Surface active agents; Thrombosis; Tumors
• ISSN: 1791-2997; 1791-3004
• DOI: 10.3892/mmr.2019.10084

Anti-phospholipid syndrome (APS) is a systematic autoimmune disease that is associated with presence of antiphospholipid antibodies (aPL), recurrent thrombosis, and fetal morbidity in pregnancy. Toll-like receptor-4 (TLR-4), a member of TLR family, is known to have a fundamental role in pathogen recognition and activation of innate immunity. The [beta]2-glycoprotein I ([beta]2GPI), a protein circulating in the blood at a high concentration, is able of scavenging lipopolysaccharide (LPS) and clear unwanted anionic cellular remnants, such as microparticles, from the circulation. Our previous study demonstrated that TLR-4 and its signaling pathways contribute to the upregulation of pro-coagulant factors and pro-inflammatory cytokines in monocytes induced by anti-[beta]2GPI in vitro. The present study aimed to define the roles of TLR-4 in vivo. C3H/HeN mice (TLR-4 intact) and C3H/HeJ mice (TLR-4 defective) were stimulated with an intraperitoneal injection with anti-[beta]2GPI-immunoglobulin G (IgG), then peritoneal macrophages and vascular endothelial cells (VECs) were extracted from treated mice, and analyses were conducted on the expression profiles of pro-inflammatory cytokines and adhesion molecules. The results demonstrated that the expression of pro-inflammatory cytokines, including tumor necrosis factor-[alpha] (TNF-[alpha]), interleukin (IL)-1p and IL-6, in the peritoneal macrophages, and adhesion molecules, including intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin, in VECs of C3H/HeN mice (TLR-4 intact) were significantly higher than those of C3H/HeJ mice (TLR-4 defective). The phosphorylation levels of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-[kappa]B (NF-[kappa]B) p65 in peritoneal macrophages and VECs from C3H/HeN mice stimulated with anti-[beta]2GPI-IgG were significantly increased compared with those from C3H/HeJ mice (TLR-4 defective). The isotype control antibody (NR-IgG) had no such effects on peritoneal macrophages and VECs. Furthermore, the inhibitors of TLR-4, p38 MAPK and NF-[kappa]B may significantly reduce the anti-[beta]2GPI-IgG-induced TNF-[alpha], IL-1[beta] and IL-6 mRNAs expression in the peritoneal macrophages from TLR-4 intact mice. The results indicated that a TLR-4 signal transduction pathway is involved in anti-[beta]2GPI-IgG-induced activation of peritoneal macrophages and VECs. This study has provided a basis for subsequent investigations to elucidate the pathological mechanisms underlying anti-phospholipid syndrome. Key words: Toll-like receptor-4, anti-[beta]2-glycoprotein I antibody, [beta]2-glycoprotein I, inflammatory cytokines, adhesion molecules