Steven A. Hoffman

Increased ICAM-1 and VCAM-1 expression in the brains of autoimmune mice

Pathogenic mechanisms of central nervous system (CNS) involvement in systemic lupus erythematosus (SLE) remain unknown. We recently reported the presence of autoantibodies in the brain tissue ex vivo of autoimmune MRL/lpr mice. We postulated that at least some of these autoantibodies are produced in situ because of B-cell entry into the brain. The blood-brain barrier (BBB) blocks the entry of most large molecules and cells into the brain. In certain CNS pathologies, however, immune cells gain entry due to elevated expression of adhesion molecules. This study looked at adhesion molecule expression, ICAM-1 and VCAM-1, in the brains of MRL/lpr mice. Using immunofluorescent antibody binding assays and confocal laser imaging, we show that expression of ICAM-1 and VCAM-1 is elevated in MRL/lpr mice brains at 4 months of age as compared to age-matched controls. These results suggest a possible mechanism for leukocyte entry into the brains of autoimmune mice that in turn suggest immune-mediated pathology in CNS-lupus.

Autoimmune-induced damage of the midbrain dopaminergic system in lupus-prone mice

Spontaneous development of lupus-like disease is accompanied by impaired dopamine catabolism and degenerating axon terminals in the mesencephalon of MRL-lpr mice. We presently examine the hypothesis that systemic autoimmunity affects the central dopaminergic system in behaviorally impaired animals. The functional damage of the nigrostriatal pathway was assessed from rotational behavior after a single injection of the D1/D2-receptor agonist apomorphine. Neurodegeneration in the midbrain was estimated by Fluoro Jade B (FJB) staining. The causal role of autoimmunity was tested by comparing asymptomatic and diseased MRL-lpr mice, and by employing the immunosuppressive drug cyclophosphamide. Damage of dopaminergic neurons was assessed by tyrosine-hydroxylase (TH) staining of the midbrain. Apomorphine induced significant asymmetry in limb use, which lead to increased circling in the diseased MRL-lpr group. While FJB-positive somas were not seen in the striatum, increased staining in the substantia nigra (SN) and ventral tegmental area (VTA) were detected in behaviorally impaired MRL-lpr mice, but not in age-matched controls. Reduced brain mass and increased levels of TNF-alpha in their cerebrospinal fluid (CSF) suggested cerebral atrophy and inflammation. In addition, CSF was neurotoxic to a dopaminergic progenitor cell line. Immunosuppression attenuated CSF cytotoxicity, TNF-alpha levels, and midbrain neurodegeneration. Supportive of the notion that dying neurons were dopaminergic, the SN of autoimmune mice showed approximately a 35% reduction in the number of TH-positive cells. A three-fold increase in serum brain-reactive antibodies accompanied this loss. Although the source of toxic mediator(s) remains unknown, present results are consistent with the hypothesis that autoimmunity-induced destruction of mesonigral and mesolimbic dopaminergic pathways contributes to the etiology of aberrant behavior in an animal model of neuropsychiatric lupus.

Immunoglobulin binding to brain in autoimmune mice.

Brain-reactive autoantibodies (BRAA) are thought to play an important role in central nervous system (CNS) manifestations of systemic lupus erythematosus (SLE). Previous studies have shown the existence of BRAA in human and murine SLE. This study was undertaken to establish and characterize the presence of autoantibody binding to brain of autoimmune mice. Laser confocal microscopy was performed on frozen brain sections to detect the presence of immunoglobulin (Ig) in the brain of MRL/lpr and BXSB mice and compare that to control strains of MRL/mp and C57BL/6 mice. There was a dramatic increase in fluorescence in the brains of MRL/lpr and BXSB at 4 months of age. There was little or no Ig detected in the brains of control mice. This increase in presence of Ig in the autoimmune mouse brain was paralleled by an increase in the serum titers of BRAA and anti-DNA autoantibodies as determined by ELISA. These studies provide another link between the existence of brain-reactive autoantibodies and altered CNS functioning.

Chronic Immune Complex Disease: Behavioral and Immunological Correlates

Using a fear avoidance paradigm, behavioral effects were seen in Sprague-Dawley rats in which chronic immune complex disease was induced. These effects were related to changes in urine protein that developed during the course of the experiment. Experimental animals also had glomerular deposits of rat gamma globulin and BSA as determined by immunofluorescence; C3 deposits were observed in half of these animals. BSA and/or rat γ-globulin, but not C3, was seen in the choroid plexus of half of the experimental animals. This is the first study to report behavioral changes associated with the induction of chronic immune complex disease in experimental animals.

Brain specific autoantibodies in murine models of systemic lupus erythematosus

Autoantibodies which bind to integral membrane proteins of brain were tested for their ability to bind to cross-reactive antigens on non-neural tissue. Both brain specific autoantibodies and antibodies which bind to cross-reactive antigens were found. There were two types of brain reactive autoantibodies which could not be adsorbed by non-neural tissue. One type was adsorbable by crude cell membrane preparations of brain. The second type was reactive against integral membrane proteins of brain, but not adsorbable by any of the crude membrane preparations tested. Autoantibodies of the first type reacted against integral membrane proteins with apparent molecular weights of 75, 70, 62, 50, 27, 24 and 20 kDa, as determined by gel electrophoresis and immunoblotting. As in previous studies, a diversity of brain reactive autoantibodies were found. The greatest numbers and strongest banding patterns were seen in the autoimmune strains of mice. The non-autoimmune strain displayed these autoantibodies at much lower levels. These results are the first to find brain specific autoantibodies, from autoimmune mice, against integral brain membrane antigens. The data support the idea that there is a sub-population of brain reactive autoantibodies which are involved in the pathogenesis of neuropsychiatric manifestations in immunologic disorders, particularly systemic lupus erythematosus.

Characterization of brain-reactive autoantibodies in murine models of systemic lupus erythematosus

Using the Western blot technique we analyzed the sera of five strains of mice that develop a disease like systemic lupus erythematosus (SLE), along with two normal strains, for their binding specificities against isolated mouse integral brain membrane proteins. This report describes the distribution and frequency of the more than 200 brain-reactive autoantibodies in the 126 animals tested and verifies the hypothesis of diversity in anti-brain antibodies produced during autoimmune conditions such as SLE. These results emphasize the importance of characterizing the brain-reactive autoantibodies in the sera or cerebrospinal fluid of SLE patients with central nervous system involvement.

Religiosity and Adolescent Substance Use in Central Mexico: Exploring the Influence of Internal and External Religiosity on Cigarette and Alcohol Use

This study explores the multidimensional nature of religiosity on substance use among adolescents living in central Mexico. From a social capital perspective, this article investigates how external church attendance and internal religious importance interact to create differential pathways for adolescents, and how these pathways exert both risk and protective influences on Mexican youth. The data come from 506 self-identified Roman Catholic youth (ages 14–17) living in a semi-rural area in the central state of Guanajuato, Mexico, and attending alternative secondary schools. Findings indicate that adolescents who have higher church attendance coupled with higher religious importance have lower odds of using alcohol, while cigarette use is lower among adolescents who have lower church attendance and lower religious importance. Adolescents are most at risk using alcohol and cigarettes when church attendance is higher but religious importance is lower. In conclusion, incongruence between internal religious beliefs and external church attendance places Mexican youth at greater risk of alcohol and cigarette use. This study not only contributes to understandings of the impact of religiosity on substance use in Mexico, but highlights the importance of understanding religiosity as a multidimensional phenomenon which can lead to differential substance use patterns.

B and T cells in the brains of autoimmune mice

Systemic lupus erythematosus (SLE) is an autoimmune disorder that can involve the central nervous system (CNS). Recently, we reported the presence of autoantibodies bound to the brain tissue of murine models of lupus; MRL/lpr and BXSB. We postulated that the source of these autoantibodies was in part due to in situ production, caused by the entry of B and T cells. Frozen brain sections of MRL/lpr and BXSB at 1 and 4 months of age were stained for CD3 (T cells) and CD19 (B cells) markers using an immunofluorescent antibody binding assay. Confocal fluorescence microscopy showed both CD3(+) and CD19(+) cells at 4 months of age only in MRL/lpr mice. There were no lymphocytes seen in the other autoimmune model, BXSB. Results suggest a difference in the mechanisms by which autoantibodies access the brain in these two autoimmune models of lupus.

Circulating brain-reactive autoantibodies and behavioral deficits in the MRL model of CNS lupus

Brain-reactive autoantibodies (BRAA) are hypothesized to play a role in the neuropsychiatric manifestations that accompany systemic lupus erythematosus (SLE). The present study tests the proposed relation between circulating BRAA and behavioral deficits in lupus-prone MRL/lpr mice. Two age-matched cohorts born at different times were used to test the relationship in the context of altered disease severity. Significant correlations between autoimmunity and behavior were detected in both cohorts. These results are the first to report correlations between behavior and autoantibodies to integral membrane proteins of brain, supporting the hypothesis that BRAA contribute to the behavioral dysfunction seen in lupus.

Intrathecal antibodies and brain damage in autoimmune MRL mice.

Neuropsychiatric (NP) manifestations and brain pathology are poorly understood and potentially fatal concomitants of systemic lupus erythematosus (SLE). For many years, autoantibodies to brain tissue (i.e., brain-reactive antibodies, BRA) were proposed as a key factor in pathogenesis of CNS manifestations. Recent evidence suggests that intrathecal BRA, rather than serum autoantibodies, are a better predictor of disturbed brain morphology and function. We presently test this hypothesis by examining the relationship among BRA in cerebrospinal fluid (CSF), behavioral deficits, and brain pathology in a well-established animal model of CNS lupus. We showed earlier that significant diversity in disease manifestations within genetically homogenous MRL-lpr mice allows for constructive and informative correlational analysis. Therefore, levels of CSF antibodies were presently correlated with behavioral, neuropathological and immune measures in a cohort of diseased MRL-lpr males (N=40). ELISA, Western Blotting, standardized behavioral battery, digital planimetry, HE staining, and immunohistochemistry were employed in overall data collection. The IgG antibodies from CSF were binding to different regions of brain parenchyma, with dentate gyrus, amygdale, and subventricular zones showing enhanced immunoreactivity. High levels of CSF antibodies correlated with increased immobility in the forced-swim test and density of HE(+) cells in the paraventricular nucleus. Peripheral measures of autoimmunity were associated with other deficits in behavior and neuropathology. This correlation pattern suggests that etiology of brain damage in lupus-prone mice is multifactorial. Intrathecal BRA may be important in altering motivated responses and activity of major neuroendocrine axes at the onset of SLE-like disease.