Estudio de biomarcadores en pacientes con Síndrome de Guillain-Barré

Abstract

Guillain-Barré syndrome (GBS) is an acute inflammatory neuropathy with a heterogeneous presentation. It is considered a paradigmatic post-infectious autoimmune disease. Although there is evidence to support the role of autoantibodies in its pathogenesis, and anti-ganglioside antibodies are detected in up to half of GBS patients, the target antigens remain unknown in a substantial proportion of patients. One of the infectious agents that can cause GBS is Zika virus (ZIKV). Recent outbreaks of this virus in South America have highlighted this association, but the mechanisms involved in its pathogenesis are still unknown. The molecular mimicry observed between other infectious agents and some components of the peripheral nerve suggests that GBS in patients who have suffered Zika virus infection (ZIKV-GBS) may develop by a mechanism of post-infectious autoimmunity. To try to elucidate the targets of the humoral response in GBS, we screened for serum autoantibodies targeting peripheral nervous tissue, cells and purified antigens in a Spanish GBS cohort including 100 patients diverse in terms of infectious background (sporadic GBS), and in a Colombian cohort of 31 patients with ZIKV-GBS, representing a more homogeneous cohort from a clinical and triggering germ point of view. In the Spanish GBS cohort, screening included anti-ganglioside and anti-nodal/paranodal antibodies; immunocytochemistry (ICC) in human neuroblastoma-derived motor neurons and murine dorsal root ganglion (DRG) neurons, and immunohistochemistry (IHC) in monkey peripheral nerve sections. Staining patterns of patients and controls, and the prognostic value of anti-ganglioside antibodies were analysed. None of the GBS patients reacted against the tested nodal/paranodal proteins, and 61 (61%) were positive for at least one anti-ganglioside antibody. GBS sera reacted against DRG neurons more frequently than controls, both IgG (6%vs0%) and IgM (11%vs2.2%). No differences were observed in the proportion of patients reacting against neuroblastoma neurons. Reactivity against monkey nerve tissue was frequently detected in both patients and controls, but specific patterns were only detected in GBS patients: IgG from 13 patients reacted against Schwann cells (SC). Finally, we confirmed that anti-GM1 IgG antibodies are associated with a worse prognosis at one year. In the screening of ZIKV-SGB patients, anti-ganglioside and anti-nodal/paranodal antibodies were tested; and ICC was performed in rat DRG neurons and SC. Thirty-one ZIKV-GBS patients were compared with 99 ZIKV-infected patients without GBS and 47 non-ZIKV controls. None of the patients were positive for any anti-nodal/paranodal antibody, and no significant association was observed with any anti-ganglioside antibody. The reactivity of IgG antibodies to CS (6.5%) and IgM antibodies to GRD neurons (32.3%) and CS (19.4%) was significantly higher in the ZIKV-GBS group compared to controls. Immunoprecipitation and mass spectrometry were performed on the positive ZIKV-GBS sera, and candidate antigens were validated by ELISA and cell-based assays; however, none of them could be confirmed as a novel autoantibody in ZIKV-SGB. Therefore, our study confirms that (1) GBS patients show a heterogeneous repertoire of autoantibodies targeting nerve cells and structures although the infectious background is homogeneous, (2) gangliosides are the most frequent antigens in GBS patients and have prognostic value, (3) new autoantibody discovery experiments may elucidate other target antigens in GBS.

Date of Award	22 Apr 2022
Original language	Spanish
Supervisor	Illa Sendra, Maria Isabel (Tutor) & Querol Gutierrez, Luis Antonio (Director)