Up to date consent was obtained from all subjects. spatial information is usually significantly lower for place cells from DNRAb?+ mice (area 1 of the hippocampus; CNS, central nervous system; CSF, cerebrospinal fluid; C3, C4, complements 3 and 4, respectively; DMARD, disease-modifying drugs; DNRAb, anti-DNA antibody reactive to the GluN2A and GluN2B subunits of the NMDAR; dsDNA, double stranded DNA; DWEYS, amino acid consensus sequence (D/E, W, D/E, Y, S/G) for DNRAb binding; FA, Freund’s adjuvant; HC, CGP77675 healthy control; HEK-293T, human embryonic kidney 293?T cell; IgG, immunoglobulin G; i.p, intraperitoneally; LPS, lipopolysaccharide; MAP, multi-antigenic polylysine backbone; NMDAR, N-methyl-d-aspartate receptor; NOR, novel object acknowledgement; NPSLE, neuropsychiatric lupus; OPM, object place memory; SELENA, security of estrogens SNF2 in lupus erythematosus national assessment; SLE, systemic lupus erythematosus; SLEDAI, systemic lupus erythematosus disease activity index; SLICCDI, systemic lupus international collaborating clinics damage index Keywords: Lupus, Neuropsychiatric lupus, CA1 place cell, Hippocampus, Mouse lupus model Highlights ? Lupus patients with NMDAR-reactive antibodies (DNRAbs) show impaired spatial memory. ? Mice in which DNRAbs penetrate the hippocampus have defective CA1 place cells. ? CA1 and CA3 pyramidal cells exposed to DNRAbs display reduced dendritic processes. ? DNRAb exposure initiates a progressive compromise in pyramidal neurons. ? Lupus antibody effects evolve even after DNRAbs are no longer present in the brain. 1.?Introduction The autoimmune disease systemic lupus erythematosus (SLE) affects multiple organs; most organ damage is initiated by autoantibody deposition that triggers subsequent inflammatory reaction (Tsokos, 2011). Neuropsychiatric lupus (NPSLE) refers to the neurologic manifestations of SLE that are present in 30C80% of patients (Nowicka-Sauer et al., 2011). These symptoms develop insidiously, cause disability, and significantly diminish quality of life (Appenzeller et al., 2009). Impaired cognition is usually reported frequently in clinically stable SLE patients that do not have other NPSLE manifestations or inflammation in the central nervous system (CNS) (Toledano et al., 2013). Despite the high prevalence of cognitive dysfunction and emotional disturbance in NPSLE patients, the wide array of symptoms attributable to NPSLE has hampered mechanistic understanding. When DNRAbs access the brain through a damaged bloodCbrain barrier (BBB) (Hirohata et al., 2014), they are likely to cause non-focal CNS manifestations of NPSLE (examined in Diamond et al., 2013). Notably, DNRAbs have been extracted from brain tissue of SLE patients (Kowal et al., 2006) and elevated DNRAb titers in cerebrospinal fluid (CSF) associate with NPSLE symptoms (Arinuma et al., 2008, DeGiorgio et al., 2001, Lauvsnes and Omdal, 2012, Yoshio et al., 2006). DNRAbs bind a consensus sequence (D/E W D/E Y S/G, or DWEYS for short) present in the extracellular domains of the GluN2A and GluN2B subunits (Paoletti, 2011). Mechanistic studies show that CGP77675 DNRAbs preferentially bind the open configuration of the NMDAR, augment NMDAR-mediated synaptic potentials, and, at higher concentration, trigger mitochondrial stress and apoptosis through binding specifically to GluN2A-containing NMDARs (Faust et al., 2010). DNRAbs that have been isolated from serum of SLE patients and intravenously transferred to mice lead to death of hippocampal neurons and impaired memory flexibility after the mice are given lipopolysaccharide (LPS) to impair the integrity of the BBB within the hippocampus (Kowal et al., 2006). We have developed an in vivo model in which BALB/c mice synthesize DNRAbs following immunization with a configuration of the consensus sequence multimerized on a polylysine backbone (termed MAP-DWEYS), while BALB/c mice immunized with the polylysine backbone alone (MAP-core) do not (Kowal et al., 2004). This model allows us to evaluate DNRAbs as causal brokers of neuronal injury, independent of other autoantibodies and the high levels of systemic inflammatory mediators found in spontaneous mouse SLE models (Sakic, 2012). Circulating DNRAbs cause no detectable brain pathology in MAP-DWEYS immunized mice with an intact BBB. However, upon exposure to LPS, mice have 20C25% loss of hippocampal neurons (occurring within the first week post-LPS) and prolonged memory impairment, assessed in the T-maze and CGP77675 the Morris water maze (Kowal et al., 2004). Here we show that SLE patients with high serum titers of DNRAbs exhibit a selective impairment in spatial cognition compared to healthy subjects. Moreover, DNRAbs in mice also lead to a selective spatial memory impairment, associated with functional and structural abnormalities in the surviving hippocampal pyramidal neurons. These alterations evolve after the DNRAbs are no longer detectable in brain tissue and are sustained for months thereafter. 2.?Materials and Methods 2.1. Human.