Yoshiyuki Arinuma

Blood-brain barrier damages and intrathecal synthesis of anti-N-methyl-D-aspartate receptor NR2 antibodies in diffuse psychiatric/ neuropsychological syndromes in systemic lupus erythematosus

IntroductionAlthough neuropsychiatric systemic lupus erythematosus (NPSLE) is one of the recalcitrant complications of the disease, its pathogenesis still remains unclear. Previous studies revealed that antibodies reactive with NMDA (N-methyl-D-aspartate) receptor NR2 (anti-NR2) are elevated in cerebrospinal fluid (CSF) of patients with diffuse psychiatric/neuropsychological syndromes (diffuse NPSLE), which is usually more recalcitrant than neurologic syndromes of NPSLE (focal NPSLE). Two mechanisms have been implicated for the elevation of CSF IgG, including intrathecal synthesis and transudation through the damaged blood-brain barrier (BBB). The present study was designed in order to elucidate the roles of BBB function and intrathecal synthesis of anti-NR2 in the elevation of CSF anti-NR2 with regard to the severity in NPSLE.MethodsPaired serum and CSF samples were obtained from 81 systemic lupus erythematosus (SLE) patients when they presented active neuropsychiatric manifestations, and from 22 non-SLE control patients with non-inflammatory neurological diseases. The 81 SLE patients consisted of 55 patients with diffuse NPSLE, including 23 patients with acute confusional state (ACS), the severest form of diffuse NPSLE, and 26 patients with neurologic syndromes or peripheral nervous system involvement (focal NPSLE). IgG anti-NR2 and albumin were measured by ELISA. BBB function and intrathecal synthesis of anti-NR2 were evaluated by Q albumin and by CSF anti-NR2 index, respectively.ResultsCSF anti-NR2 levels, Q albumin and CSF anti-NR2 index were significantly higher in NPSLE than in non-SLE control. CSF anti-NR2 levels and Q albumin were significantly higher in ACS than in non-ACS diffuse NPSLE (anxiety disorder, cognitive dysfunction, mood disorder and psychosis) or in focal NPSLE, whereas there was no significant difference in CSF anti-NR2 index among the 3 groups. CSF anti-NR2 levels were significantly correlated with Q albumin in diffuse NPSLE (r = 0.3754, P = 0.0053).ConclusionsThese results demonstrate that the severity of BBB damages plays a crucial role in the development of ACS, the severest form of diffuse NPSLE, through the accelerated entry of larger amounts of anti-NR2 into the central nervous system.

Brain MRI in patients with diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematosus

Background Manifestations in neuropsychiatric systemic lupus erythematosus (NPSLE), especially active diffuse NPSLE syndromes, are some of the most difficult complications of the disease. For the evaluation and the diagnosis of central nervous system manifestations, including NPSLE, MRI is a very useful tool to detect the various abnormalities. However, the relationship between brain MRI findings and clinical variables has not yet been clarified in patients with diffuse NPSLE. Objectives The aim of this study is to investigate the pathogenesis of diffuse NPSLE, by comparing various parameters such as serum autoantibodies and cytokines in cerebrospinal fluid (CSF) with abnormal findings revealed on brain MRIs in patients with diffuse NPSLE. Methods Fifty-three patients with diffuse NPSLE admitted to our University Hospital from 1992 to 2012 were exhaustively enrolled in this study. Their medical charts and brain MRI scans were reviewed. The relationship of MRI abnormalities with various parameters was analysed. Results As many as 25 of 53 patients (47.2%) had abnormal MRI findings. MRI findings improved after treatment in 10 of 17 patients for whom follow-up studies were available. MRI abnormalities were not correlated with age at the onset of diffuse NPSLE. However, the disease duration of SLE was significantly longer in patients with abnormal MRI findings (p=0.0009). MRI abnormalities were not significantly associated with serum autoantibodies. However, there were significant elevations of the CSF protein level (p=0.0106) and the CSF interleukin 6 level (p=0.0225) in patients with abnormal MRI findings. Patients with MRI abnormalities showed significantly higher overall mortality (p=0.0348). Conclusions The results revealed that MRI abnormalities in diffuse NPSLE might be heterogeneous with regard to their reversibility. These data also indicate that patients with diffuse NPSLE and MRI abnormalities have more severe inflammation in the central nervous system related to the activity of diffuse NPSLE, as evidenced by poorer prognosis.

Association of antibodies to the NR1 subunit of N-methyl-D-aspartate receptors with neuropsychiatric systemic lupus erythematosus

Abstract Objective: To determine epitope reactivity of autoantibodies to N-methyl-D-aspartate (NMDA) receptor NR1 subunit and their association with neuropsychiatric systemic lupus erythematosus (NPSLE). Methods: Paired serum and CSF specimens were obtained from 41 patients with NPSLE (22 with diffuse psychiatric/neuropsychological syndromes [diffuse NPSLE] and 19 with neurologic syndromes or polyneuropathy [focal NPSLE]), 21 patients with various rheumatic diseases other than SLE (non-SLERD). Sera were also obtained from 27 SLE patients without neuropsychiatric manifestations (non-CNS SLE). Antibodies to murine NR1 (mNR1) or to 4 different preparations of synthetic 25-amino-acid (AA) peptides of human NR1 were measured by enzyme-linked immune sorbent assay (ELISA). Results: Serum anti-mNR1 levels were significantly higher in NPSLE than in non-SLERD. Sera from NPSLE patients bound efficiently to the AA residues 19–44 from the N-terminus of NR1 (NR1-A) or 56–81 (NR1-C). Accordingly, serum anti-NR1-A and anti-NR1-C were also elevated in NPSLE compared with non-SLERD. Of note, anti-NR1-A as well as anti-NR1-C levels in CSF, but not in sera, were significantly elevated in diffuse NPSLE compared with focal NPSLE or with non-SLERD. Conclusion: These results suggest that autoantibodies to NMDA receptor NR1, especially to the AA residues 19–44 and 56–81 from the N-terminus play a pivotal role in the pathogenesis of diffuse NPSLE.

Brain MRI in patients with acute confusional state of diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematosus

Abstract Objective: The objective of this study is to explore the characteristics of brain MRI abnormalities in acute confusional state (ACS) in neuropsychiatric systemic lupus erythematosus (NPSLE). Methods: Thirty-six patients with ACS admitted to our institutions from 1992 to 2015 were exhaustively enrolled. Their medical charts and brain MRI scans were reviewed. Results: Eighteen of 36 ACS patients had MRI abnormalities, mostly high-intensity lesions of various sizes in the cerebral white matter. MRI abnormalities improved after treatment in 12 of 14 patients in follow-up studies. MRI abnormalities were not correlated with ages at the onset of ACS, disease durations of SLE, the presence of anti-DNA, anti-phospholipid or anti-ribosomal P antibodies, or IL-6 levels in sera or cerebrospinal fluid. Notably, MRI abnormalities were significantly associated with the presence of serum anti-Sm antibodies (p = 0.0067). Finally, eight of the 18 patients with MRI abnormalities, but none of the other 18 patients without MRI abnormalities, died from active SLE. Thus, MRI abnormalities significantly increased the mortality in ACS (p = 0.0013, HR =10.36 [95% CI: 2.487–43.19]). Conclusion: These results demonstrate that patients with ACS with MRI abnormalities have more severe diseases, resulting in poorer prognoses. The data also indicate that anti-Sm is involved in the development of MRI abnormalities in ACS.

Effects of anti-IL-6 receptor antibody on human monocytes

Abstract Objective. To explore the effects of anti-IL-6 receptor antibody, tocilizumab on function of human monocytes. Methods. Monocytes from healthy donors were cultured in the presence of staphylococcal enterotoxin B (SEB) with pharmacologically attainable concentrations of tocilizumab or control IgG. The expression of IL-6 mRNA was determined using quantitative RT-PCR. The expression of CD80 and CD86 and the induction of apoptosis of monocytes were measured using flow cytometry. Results. Tocilizumab promoted apoptosis of SEB-stimulated monocytes. The induction of apoptosis of monocytes by tocilizumab were reversed by addition of IgG, but not IgG F(ab’)2 fragments. Tocilizumab significantly suppressed the expression of CD80, but not that of CD86, on SEB- stimulated monocytes. Finally, tocilizumab significantly suppressed the expression of mRNA for IL-6 of monocytes stimulated with SEB. Conclusions. These results demonstrate that one of the mechanism of action of tocilizumab involves the induction of apoptosis of monocytes, which requires interaction with Fc receptor on monocytes. Moreover, the data also indicate that tocilizumab inhibit IL-6 production of monocytes at mRNA levels.

Lupus antibodies induce behavioral changes mediated by microglia and blocked by ACE inhibitors

Cognitive impairment occurs in 40–90% of patients with systemic lupus erythematosus (SLE), which is characterized by autoantibodies to nuclear antigens, especially DNA. We discovered that a subset of anti-DNA antibodies, termed DNRAbs, cross reacts with the N-methyl-D-aspartate receptor (NMDAR) and enhances NMDAR signaling. In patients, DNRAb presence associates with spatial memory impairment. In a mouse model, DNRAb-mediated brain pathology proceeds through an acute phase of excitotoxic neuron loss, followed by persistent alteration in neuronal integrity and spatial memory impairment. The latter pathology becomes evident only after DNRAbs are no longer detectable in the brain. Here we investigate the mechanism of long-term neuronal dysfunction mediated by transient exposure to antibody. We show that activated microglia and C1q are critical mediators of neuronal damage. We further show that centrally acting inhibitors of angiotensin-converting enzyme (ACE) can prevent microglial activation and preserve neuronal function and cognitive performance. Thus, ACE inhibition represents a strong candidate for clinical trials aimed at mitigating cognitive dysfunction.

Effects of CTLA4-Ig on human monocytes

BackgroundAbatacept, a CTLA4-Ig fusion protein attenuates T cell activation by inhibiting the CD80/86-CD28 costimulatory pathway that is required for the proper T cell activation and thus displays beneficial effects in the treatment of rheumatoid arthritis (RA). Although some studies have disclosed the in vitro effects of this biological agent on the immune-competent cells, the precise mechanisms of action in RA still remain unclear. The current studies were therefore undertaken to explore the effects of abatacept on monocytes in detail.MethodsMonocytes from healthy donors were cultured in the presence of staphylococcal enterotoxin B (SEB) with pharmacologically attainable concentrations of abatacept or control IgG-Fc. The expression of CD80 and CD86 and the induction of apoptosis of monocytes were measured by flow cytometry. The expression of CD80 and CD86 messenger RNA (mRNA) was determined by quantitative RT-PCR.ResultsAbatacept promoted apoptosis of SEB-stimulated monocytes. The induction of apoptosis of monocytes by these biological agents was reversed by the addition of IgG, but not IgG-F(ab′)2 fragments. Furthermore, abatacept significantly suppressed the expression of CD80, but not that of CD86 at protein levels. Finally, abatacept significantly suppressed the expression of mRNA for CD80 of monocytes stimulated with SEB, but not that of CD86.ConclusionsThese results demonstrate that one of the mechanisms of action of abatacept involves the induction of apoptosis of monocytes, which involves interaction with Fc receptor on monocytes. Moreover, the data also demonstrate that abatacept selectively suppresses the expression of CD80 at mRNA levels.

Imaging of Neuropsychiatric Systemic Lupus Erythematosus

The diagnosis of neuropsychiatric manifestations in systemic lupus erythematosus (NPSLE) is challenging. Neuroimaging is very important technique for the evaluation of abnormalities occurred in the central nervous system (CNS). Computed tomography (CT) scan is one of the common techniques and is very useful to detect a large lesion such as ischemic stroke, hemorrhage and tumor, providing help to rule out CNS diseases other than SLE. Magnetic resonance imaging (MRI) is the best tool at present to detect parenchymal lesions in the CNS. Conventional MRI figures out exact abnormalities in the CNS causing neurologic or psychiatric symptoms. However, it should be remembered that MRI abnormalities in patients with NPSLE are not always specific for NPSLE. New MRI techniques can give us more detailed information in patients with NPSLE in addition to findings by conventional MRI. Functional analysis of the CNS by imaging system would be promising.

Anti-ribosomal P protein antibodies influence mortality of patients with diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematous involving a severe form of the disease

Abstract Objectives: The aim of this study is to clarify the effect of various autoantibodies on overall mortality in patients with diffuse psychiatric/neuropsychological syndromes in SLE (diffuse NPSLE). Methods: Fifty-five patients with diffuse NPSLE admitted from 1992 to 2017 had met inclusion criteria and were recruited for this study. The relationship of various serum autoantibodies with mortality was retrospectively analyzed based on the medical charts. Results: Of 55 patients, 14 patients [25.5%] had died during the observation period (2728 [22-8842] days (median [range])). The 5-year, 10-year, 15-year and 20-year mortality rates were 18.8%, 21.9%, 36.9% and 47.4%, respectively. Among various serum autoantibodies at the onset of diffuse NPSLE, only the presence of anti-ribosomal P protein antibodies (anti-ribo P) significantly increased the risk for death (relative risk 2.262, 95% confidence interval 1.276–4.417, p = 0.005). Of 14 fatal patients, 10 patients had died within 1 y after the onset of diffuse NPSLE. Remarkably, 7 of 10 patients with positive anti-ribo P had died of the severe complication primarily attributed to SLE except for one patient. Conclusions: The presence of anti-ribo P is a significant risk factor for overall poor prognosis in patients with diffuse NPSLE, involving a fatal complication by SLE.

13 Antibody-mediated neuropsychiatric lupus

Neuropsychiatric lupus manifestations, especially the common disorders of mood and cognition, can be mediated by cytokines or by antibodies. In particular, a subset of anti-DNA antibodies has been shown to bind the N-methyl d-aspartate receptor. The antibodies preferentially bind the active configuration of the receptor, augmenting the effects of ligand binding. Meta-analysis has confirmed that high serum titers of these antibodies, present in 30%–40% of SLE patients, are associated with cognitive impairment. In a mouse model, antibody within the circulation is not harmful to the brain unless there is a breach in blood-brain barrier integrity. If there is an insult to the hippocampal vasculature, antibody gains access to hippocampal neurons and mediates tissue damage in 2 distinct stages. First, there is immediate antibody-mediated excitotoxicity causing neuronal loss. Second, after antibody is no longer present in the brain, there is microglial activation and dendritic pruning of surviving neurons. The brain injury that ensues leads to impairment in spatial cognition. These studies suggest there are two distinct approaches to therapy; one might modulate the initial damage by neutralising the pathogenic antibodies or maintaining blood-brain barrier integrity, the other might mitigate the later damage by inhibiting microglial cells.