Carbohydrate mimicry between human ganglioside GM1 and Campylobacter jejuni lipooligosaccharide causes Guillain-Barre syndrome

Abstract

Molecular mimicry between microbial and self-components is postulated as the mechanism that accounts for the antigen and tissue specificity of immune responses in postinfectious autoimmune diseases. Little direct evidence exists, and research in this area has focused principally on T cell-mediated, antipeptide responses, rather than on humoral responses to carbohydrate structures. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, occurs 1-2 wk after various infections, in particular, Campylobacter jejuni enteritis. Carbohydrate mimicry [Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-] between the bacterial lipooligosaccharide and human GM1 ganglioside is seen as having relevance to the pathogenesis of Guillain-Barré syndrome, and conclusive evidence is reported here. On sensitization with C. jejuni lipooligosaccharide, rabbits developed anti-GM1 IgG antibody and flaccid limb weakness. Paralyzed rabbits had pathological changes in their peripheral nerves identical with those present in Guillain-Barré syndrome. Immunization of mice with the lipooligosaccharide generated a mAb that reacted with GM1 and bound to human peripheral nerves. The mAb and anti-GM1 IgG from patients with Guillain-Barré syndrome did not induce paralysis but blocked muscle action potentials in a muscle-spinal cord coculture, indicating that anti-GM1 antibody can cause muscle weakness. These findings show that carbohydrate mimicry is an important cause of autoimmune neuropathy.

Fig. 1.

Rabbit GBS model sensitized with C. jejuni LOS. (a) Carbohydrate mimicry of GM1 ganglioside by the LOS of C. jejuni (CF 90-26) from a GBS patient. GM1 is located in the nerve cell membrane. The LOS that mimics GM1 is in the outer part of the cell wall of C. jejuni. □, Galactose; [hwyschool], N-acetylgalactosamine; ▪, glucose; ▾, N-acetylneuraminic acid; Cer, ceramide; Hep, heptose. (b) Presence or absence of the GM1 epitope in bacterial LOS-immunized rabbits. Cholera toxin B subunit reacts with the C. jejuni LOS (lane 1) but not with E. coli K12 LOS (lane 2) or S. minnesota R595 LOS (lane 3). (c) Rabbit with flaccid limb weakness induced by sensitization with C. jejuni LOS. Rabbit Cj-18 lays splayed out, all extremities extended, head on the floor, instead of sitting upright in the usual compact, hunched posture. (d) Anti-ganglioside Ab from rabbits that developed limb weakness after sensitization with C. jejuni LOS. Of the bovine brain gangliosides, plasma IgG from rabbit Cj-18 binds to GM1 (lane 1), isolated GM1 from bovine brain (lane 2), and GM1 from rabbit peripheral nerve (lane 3). The IgGs are from rabbits Cj-14, Cj-15, and Cj-16, and the GM1 is from rabbit peripheral nerve (lane 3). (e–h) Macrophages in nerve fibers. Shown are cross sections of the cauda equina from rabbit Cj-18. (e and f) Toluidine blue stain. Macrophages are present in the nerve fibers (arrowheads). The initial degenerated axon stage also is shown (arrow in f). Demyelination and remyelination are rare, and no inflammatory cells exist in the endoneurium. (g and h) Electron micrographs of nerve fibers with macrophage infiltration. The nerve fiber in g is the same as in e. Macrophages (M) occupy the periaxonal space between the atrophic axons (A) and the surrounding myelin sheaths, which appear almost normal. (Scale bars = 10 μm.) (i) Wallerian-like degeneration of nerve fibers. Shown are cross sections of the sciatic nerve from rabbit Cj-14 killed 39 days after onset. Toluidine blue stain was used. Myelin ovoids produced by Wallerian-like degeneration of the myelinated fibers are present (arrowheads). (Scale bar = 10 μm.)

Fig. 2.

Immunoreactivity of anti-GM1 mAb. (a and b) Binding specificity of the mAb (GB2) generated by C. jejuni LOS. (a) Of the bovine brain gangliosides, it recognizes GM1 (lane 1), the GM1 isolated from bovine brain (lane 2), and the GM1 of human peripheral nerve (lane 3). (b) The mAb reacts with the C. jejuni LOS (lane 1) but not with E. coli K12 LOS (lane 2) or S. minnesota R595 LOS (lane 3). (c–f) GM1 immunoreactivity in the anterior nerve roots of the human lumbar cord with the biotin-conjugated anti-GM1 IgG from a GBS patient (c) and the anti-GM1 mAb (d–f). (c and d) Labeling is present in the myelin sheaths of both large and small myelinated axons. (e) GM1 antigenicity is localized on the myelin lamellae, plasma membrane of the outer Schwann cell process, the basal lamina, and the mitochondria and some vacuoles of an axon. (f) Labeling also is present on Schwann cell processes surrounding the nodal region of an axon. (c and d) The immunoperoxidase method was used. (e and f) The immunogold method is indicated by 15-nm gold particles. (Scale bars = 30 μmin c and d, 1 μmin e, and 2 μmin f.)

Fig. 3.

Biologic activity of anti-GM1 mAb. (a) Blockade of muscle action potentials by anti-GM1 mAb in muscle–spinal cord cocultured cells. (b) Time course of inhibition of spontaneous muscle action potentials by anti-GM1 mAb recovery after washout. The number of potentials was measured every 5 s. Arrows show times of the anti-GM1 mAb addition and exchange of the bath solution.