Anti-Ro/SAA Autoantibodies Might Represent the Antineuronal Antibodies Responsible for Cerebellar Degeneration in Sjögren's Syndrome 

Abstract

Background: Neurologic disorders are one of the most common extraglandular manifestations of Sjögren's syndrome (SjS). Central neurologic symptoms can appear in about 5% of patients with SjS. However, only a few reports of cerebellar degeneration have been reported, and the clinical features and pathologic mechanisms of cerebellar degeneration associated with SjS are unclear.Patients and methods: We recently treated cerebellar degeneration in a patient with SjS. We analyzed the serum and cerebrospinal fluid (CSF) to detect anti-Ro/anti-SjS-related antigen A (SSA) and anti-La/anti-SjS-related antigen B (SSB) antibodies. We also searched the literature for previous case reports on SjS to evaluate the characteristics of cerebellar degeneration in patients with SjS and examined whether the Ro/SSA (Ro52/tripartite motif protein [TRIM]21) protein was expressed in murine cerebellum using immunohistochemistry.Results: Although all patients were positive for anti-Ro/SSA antibodies, some patients were negative for anti-La/SSB antibodies. Anti-Ro/SSA antibodies were observed in both serum and CSF. Anti-Ro/SSA antibodies were negative in the CSF of SjS patients without central nervous system involvement. Cerebellar atrophy was observed, and sequelae remained in the majority of the patients. Autopsy findings indicated a selective loss of Purkinje cells. Ro52/TRIM21 expression was detected throughout murine brains, including the hippocampus, cerebral cortex, and cerebellum. High Ro52/TRIM21 expression was observed in Purkinje cells.Conclusions: We described the characteristics of cerebellar degeneration in patients with SjS and Ro52/TRIM21 expression in Purkinje cells of murine cerebellar tissue sections. Thus, these outcomes indicated that anti-Ro/SSA autoantibodies were likely responsible for cerebellar degeneration in SjS.