The Pathogenesis of the Demyelinating Form of Guillain-Barre Syndrome (GBS): Proteo-peptidomic and Immunological Profiling of Physiological Fluids

Abstract

Acute inflammatory demyelinating polyneuropathy (AIDP) - the main form of Guillain-Barre syndrome-is a rare and severe disorder of the peripheral nervous system with an unknown etiology. One of the hallmarks of the AIDP pathogenesis is a significantly elevated cerebrospinal fluid (CSF) protein level. In this paper CSF peptidome and proteome in AIDP were analyzed and compared with multiple sclerosis and control patients. A total protein concentration increase was shown to be because of even changes in all proteins rather than some specific response, supporting the hypothesis of protein leakage from blood through the blood-nerve barrier. The elevated CSF protein level in AIDP was complemented by activization of protein degradation and much higher peptidome diversity. Because of the studies of the acute motor axonal form, Guillain-Barre syndrome as a whole is thought to be associated with autoimmune response against neurospecific molecules. Thus, in AIDP, autoantibodies against cell adhesion proteins localized at Ranvier's nodes were suggested as possible targets in AIDP. Indeed, AIDP CSF peptidome analysis revealed cell adhesion proteins degradation, however no reliable dependence on the corresponding autoantibodies levels was found. Proteome analysis revealed overrepresentation of Gene Ontology groups related to responses to bacteria and virus infections, which were earlier suggested as possible AIDP triggers. Immunoglobulin blood serum analysis against most common neuronal viruses did not reveal any specific pathogen; however, AIDP patients were more immunopositive in average and often had polyinfections. Cytokine analysis of both AIDP CSF and blood did not show a systemic adaptive immune response or general inflammation, whereas innate immunity cytokines were up-regulated. To supplement the widely-accepted though still unproven autoimmunity-based AIDP mechanism we propose a hypothesis of the primary peripheral nervous system damaging initiated as an innate immunity-associated local inflammation following neurotropic viruses egress, whereas the autoantibody production might be an optional complementary secondary process.

Fig. 1.

A, Protein concentrations in the CSF of GBS and control patients. (B–F) Venn diagrams representing: B, proteins identified in the CSF of AIDP patients in comparison with control individuals; C, endogenous peptides and their protein precursors identified in the CSF of AIDP patients in comparison with MS and control patients; D, endogenous peptides and their protein precursors identified in the CSF of control patients in comparison to previously reported data; E, endogenous peptides corresponding to the IgG molecules identified in the CSF of AIDP patients in comparison with MS and control patients; and F, proteins and protein precursors of peptides identified in the CSF of AIDP patients and control individuals.

Fig. 2.

Simultaneous multiviral infection persists in the majority of GBS patients. A, Analysis of viral seropositivity in healthy patients (HD) and AMAN and AIDP patients studied using ELISA. Light pink, orange, and white indicate the percentages of infected individuals, individuals with borderline status, and uninfected persons, respectively. The plots on the right represent the percentage of individuals with multiple seropositive results for the indicated viruses. The gray area, crosshatched area, and area inside the bold line represent CMV, HHV-6, and HSV-1,2 seropositivity, respectively. The intersection area restricted by the red line corresponds to the simultaneous occurrence of respective viruses. The percentage of individuals who were seropositive toward all 3 viruses is indicated. B, Level of serum IgG specific for viral antigens measured by ELISA. C, Multiplex analysis of the cytokine level in the CSF of the AIDP patients, multiple sclerosis patients (MS), healthy individuals (HD), and patients with purulent (PM) and aseptic (AM) meningitis. The plots on the right demonstrate the scaled areas. Boxplots represent the interquartile range (25–75%), and the bars and dots indicate 90 and 95% confidential intervals, respectively. The boxplots filled with red indicate cytokines that were elevated in the CSF of the GBS patients in comparison with the healthy individuals.