Guillain-Barré syndrome anti-ganglioside-complex antibodies at mouse

Objectives: Anti-ganglioside antibodies are present in about half of the patients with Guillain-Barré syndrome (GBS). Recently it has been shown that a considerable proportion of these patients has serum antibodies against antigenic epitopes formed by a complex of two different gangliosides. However, direct experimental evidence for neuropathogenicity of this special category of antibodies is currently lacking. Here we explored a series of GBS and GBS-variant sera with anti-ganglioside-complex antibodies for their ability to induce complement-dependent deleterious effects at the living neuronal membrane. Methods: The neuropathophysiological potential of 31 GBS sera containing either antiGM1/GD1aor anti-GM1/GQ1b-ganglioside-complex antibodies was studied at motor nerve terminal presynaptic membranes in the mouse phrenic nerve/diaphragm muscle ex vivo experimental model. With electrophysiological measurements and confocal fluorescence microscopy we assessed and quantified the damaging effect on neuronal membranes by antiganglioside-complex antibodies. Results: We show that anti-GM1/GD1aand anti-GM1/GQ1b-ganglioside-complex positive sera can induce complement-mediated functional and morphological injury at mouse motor nerve terminals ex vivo. Of the 31 investigated anti-ganglioside-complex patient sera, 17 sera induced increases in miniature endplate potential frequency in this experimental model, mostly associated with muscle fibre twitches. Variability in potency was observed, with the anti-GM1/GD1a-complex sera inducing the most outspoken effects. Conclusions: This study demonstrates the presence of ganglioside-complexes as available antigens in living neuronal membranes and supplies proof-of-principle that anti-gangliosidecomplex antibodies in sera from GBS patients can induce complement-mediated damage. This strongly supports the hypothesis that autoimmune targeting of ganglioside-complexes is of pathogenic relevance in a proportion of GBS patients.