Neuronal uptake of anti-Hu antibody, but not anti-Ri antibody, leads to cell death in brain slice cultures

Abstract

BackgroundAnti-Hu and anti-Ri antibodies are paraneoplastic immunoglobulin (Ig)G autoantibodies which recognize cytoplasmic and nuclear antigens present in all neurons. Although both antibodies produce similar immunohistological labeling, they recognize different neuronal proteins. Both antibodies are associated with syndromes of central nervous system dysfunction. However, the neurological deficits associated with anti-Hu antibody are associated with neuronal death and are usually irreversible, whereas neurological deficits in patients with anti-Ri antibody may diminish following tumor removal or immunosuppression.MethodsTo study the effect of anti-Hu and anti-Ri antibodies on neurons, we incubated rat hippocampal and cerebellar slice cultures with anti-Hu or anti-Ri sera from multiple patients. Cultures were evaluated in real time for neuronal antibody uptake and during prolonged incubation for neuronal death. To test the specificity of anti-Hu antibody cytotoxic effect, anti-Hu serum IgG was incubated with rat brain slice cultures prior to and after adsorption with its target Hu antigen, HuD.ResultsWe demonstrated that: 1) both anti-Hu and anti-Ri antibodies were rapidly taken up by neurons throughout both cerebellum and hippocampus; 2) antibody uptake occurred in living neurons and was not an artifact of antibody diffusion into dead cells; 3) intracellular binding of anti-Hu antibody produced neuronal cell death, whereas uptake of anti-Ri antibody did not affect cell viability during the period of study; and 4) adsorption of anti-Hu antisera against HuD greatly reduced intraneuronal IgG accumulation and abolished cytotoxicity, confirming specificity of antibody-mediated neuronal death.ConclusionsBoth anti-Hu and anti-Ri antibodies were readily taken up by viable neurons in slice cultures, but the two antibodies differed markedly in terms of their effects on neuronal viability. The ability of anti-Hu antibodies to cause neuronal death could account for the irreversible nature of paraneoplastic neurological deficits in patients with this antibody response. Our results raise questions as to whether anti-Ri antibody might initially induce reversible neuronal dysfunction, rather than causing cell death. The ability of IgG antibodies to access and react with intracellular neuronal proteins could have implications for other autoimmune diseases involving the central nervous system.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-014-0160-0) contains supplementary material, which is available to authorized users.

Prolonged human neural stem cell maturation supports recovery in injured rodent CNS

“…To assess changes in the total number of grafted neurons over time, we used the specific neuronal marker Hu, w hich is expressed by all neurons, including both immature and mature postmitotic neurons (24)(25)(26) and is distinct from the hNu antibody, which specifically labels human nuclei but is not restricted to neurons (Figure 2, A, B, E inset, and Supplemental Figure 2, G-I). We found Neuronal hypertrophy is an indication of continuing cell maturation (29).…”

Synchronous Adie's syndrome and type 1 antineuronal nuclear antibody (anti-Hu)-related paraneoplastic neurological syndromes as predictors of complete response in limited-stage small-cell lung cancer: A case report

“…The prognosis is poor, with the median survival for anti-Hu patients following the onset of treatment reported to be 6 months (range, 3-35 months) (29). The recent discovery that ANNA-1 may cause neuronal cell death may account for the irreversible nature of paraneoplastic neurological deficits in patients with these autoantibodies (30).…”

Autoimmune Dementia

“…Although the detection of autoantibodies is not required to establish an AE diagnosis, the discovery of disease-associated autoantibodies conveys important information concerning the underlying immune system response in patients with AE. Whereas intracellular antibodies are commonly associated with intraparenchymal invasion of inflammatory cells, including CD8-positive cytotoxic T-cells, [30][31][32][33] and possibly neuronal autoantibody uptake, 34,35 T cell-mediated neuronal destruction is rare in patients with AE associated with autoantibodies against cell-surface antigens. 36,37 This critical difference has important implications for predicting outcomes in recovering AE patients, including the potential for neuronal survival, 38,39 and, by extension, the risk of AiD-AE.…”

“…Autoantibody uptake directly into neurons with resultant cell death as an alternate or accompanying mechanism of injury has also been demonstrated in animal models. 34,35 Longitudinal studies including formal evaluation of cognition are required to determine the prevalence of AiD-AE in patients with autoantibodies against intracellular antigens, and to consider potentially modifiable factors that may reduce the risk of cognitive impairment in the limited number of patients who stabilize with treatment.…”