Cognitive impairment of MRL mice is related to NMDA receptor-mediated inflammatory response and production of adhesion molecules in MRL/lpr mice-derived micro-vascular endothelial cells.

Abstract

Systemic lupus erythematosus (SLE) is a chronic recurrent autoimmune disease affecting almost all organs. This study was conducted to investigate cognitive impairment of SLE mice (MRL/lpr mice), and explore associated pathological mechanism. Behavior tests (open-field test, elevated plus-maze test, forced swimming test, sucrose preference test, and Morris water maze test) were conducted in MRL/MPJ and MRL/lpr mice. ELISA test was performed to determine levels of antibodies (anti-dsDNA, anti-RPA, anti-ACA, and anti-NR2a/b) and inflammatory factors [tumour necrosis factor a (TNF-a), interleukin (IL)-6, IL-8, and IL-10]. Micro-vascular endothelial cells (MVECs) were isolated, identified, and divided into MVECs (NC), anti-NR2a/2b, memantine, glycine, dexamethasone, and IL-1b groups. Cell proliferation was measured using cell counting kit-8 (CCK-8) assay, and Western blotting was applied to evaluate ELAM-1, VCAM-1, ICAM-1, IKBa, p-IKBa expression. MRL/lpr mice demonstrated lower locomotion/exploration ability, higher anxiety, obvious depression symptoms, lower learning/memory capability compared with MRL/MPJ mice. MRL/lpr mice demonstrated high levels of anti-NR2a/b antibody and auto-antibodies. NMDA receptor antagonist (memantine) significantly increased, and NMDA receptor agonist (glycine) significantly decreased MVECs proliferation compared with NC group ( p < 0.05). Memantine significantly reduced and glycine predominantly enhanced TNF-a, IL-6, IL-8, and IL-10 levels compared with NC group ( p < 0.05). NMDA receptor antagonist and agonist modulated adhesion molecules expression in MVECs. ELAM-1, VCAM-1, and ICAM-1 expressions were significantly down-modulated in memantine group, and remarkably up-modulated in glycine group compared with NC group ( p < 0.05). NMDA receptor antagonist and agonist regulated phosphorylation of p-IKBa. The above effects of memantine evenly equaled to dexamethasone, and glycine evenly equaled to IL-1b. In conclusion, cognitive impairment of MRL mice might be associated with NMDA receptor-mediated inflammatory response and production of adhesion molecules in MRL/lpr mice-derived MVECs.