The antibody repertoire of autoimmune sensory neuronopathies targets pathways of the innate and adaptive immune system. An autoantigenomic approach

Sensory neuronopathies (SNN) encompass diverse etiologies, with autoimmunity playing a major role through both cellular and humoral responses. To investigate the humoral autoantibody repertoire in autoimmune SNN, we conducted a retrospective cohort study using large Human Proteome-wide protein microarrays (HuProt 3.1, HuProt 4.0, ProtoArrays). We specifically analyzed immune system pathways targeted within the autoantigen repertoire (the autoantigenome). We included 131 participants: 44 patients with non-paraneoplastic autoimmune SNN (12 with anti-FGFR3 and/or anti-AGO antibodies), 8 with paraneoplastic SNN, and 79 controls. Findings were validated in an independent cohort of 16 SNN patients. Overrepresentation of immune-system-related proteins was assessed using the Reactome database, and serum levels of IFN-γ and IL-6 were measured with the Bio-Plex Pro™ Reagent Kit. Autoimmune SNN sera interact with significantly more immune system proteins than healthy controls (ProtoArrays: 271/863 vs. 14/863, HuProt: 112/1694 vs. 39/1694, both p < 0.0001). Overrepresentation was observed across all major immune sub-pathways, including innate and adaptive immune responses as well as cytokine signaling. Anti-FGFR3-positive SNN patients showed more frequent reactivity to immune system proteins than anti-FGFR3-negative ones. The independent SNN cohort validated the overrepresentation of targeted immune system pathways. Validation with dot blot and ELISA confirmed reactivity to TRIM21 and IL-6 and identified anti-IFN-γ-positive SNN patients. IFN-γ levels correlated weakly with levels of anti-IFN-γ antibodies (Pearson's r = 0.22, p = 0.03). We conclude that the antibody repertoire of autoimmune SNN targets pathways of the innate and adaptive immune system, potentially reflecting key disease-related immune pathways and highlighting the systemic role of immune dysregulation in SNN.