Gangliosides and Autoimmune Peripheral Nerve Diseases.

A wide range of neuroimmunological diseases, referred to as autoimmune neuropathies, affect the peripheral nervous systems (PNS). The PNS is structurally diverse with complex anatomical compartments enriched in many different myelin and neuronal glycolipids, notably gangliosides. Autoimmune neuropathies are a proportion of autoimmune neuropathies mediated by autoimmune attack due to antibodies reactive with these compartmentally localized gangliosides. Antiganglioside antibodies are principally associated with the acute paralytic disease, Guillain-Barré syndrome, and are also found in several chronic autoimmune neuropathy syndromes. These antibodies may arise spontaneously from the natural autoantibody repertoire, or be induced by infections that share structurally similar glycans to gangliosides, an immunological process often referred to as molecular mimicry. The principal infection exhibiting this structural similarity is Campylobacter jejuni, which displays mimics of GM1, GD1a, GT1a, and other gangliosides on its surface lipo-oligosaccharide. Autoantibodies thus induced bind glycan epitopes on peripheral nerve gangliosides where they activate complement and recruit macrophages, causing structural and functional disorganization of nerve conduction. Chronic autoimmune neuropathies are also associated with naturally arising IgM antibodies directed against ganglioside epitopes present on disialylated gangliosides, that induce a sensory neuropathy, and on GM1, that induce a motor neuropathy. In a third syndrome, the so-called "anti-MAG" neuropathy, the antibodies bind a sulfated glucuronic acid epitope present on myelin-associated glycoprotein and the glycolipid sulfated glucuronyl paragloboside. This review will describe the immunological, pathological, and clinical features of these disorders in the context of our broader knowledge of the ganglioside glycobiology of the peripheral nervous system.