Flagellar filament structural protein induces Sjögren's syndrome-like sialadenitis in mice

Abstract

Objective

Sjögren's syndrome (SS) is a systemic autoimmune disease that primarily affects lacrimal and salivary glands. We previously reported that FliC derived from E. coli could induce autoimmune pancreatitis-like lesions. From these results, we speculated that FliC could also induce SS-like exocrinopathy. In the present study, we investigated the effects of chronic exposure to FliC on lacrimal and salivary glands and the possibility that it might lead to an autoimmune response.

Methods

C57BL/6 mice were repeatedly injected with FliC and histological changes, serum levels of cytokine/chemokines and autoantibodies were evaluated at different time points after the final injection. The presence of sialadenitis was diagnosed by histological methods.

Results

In FliC-treated groups, 57% of subjects developed inflammatory cell infiltrates around ducts in mandibular salivary glands, but not lacrimal glands. In addition, serum levels of total IgG, IgG1 and IgG2a were significantly higher in FliC-treated groups. Intriguingly, serum anti-SSA/Ro levels were also significantly higher in FliC-treated groups. Cytokine analysis revealed that serum levels of IL-1β, IL-12p70, IL-13, IFN-γ, IL-15 and IL-23 seemed to be higher in FliC-treated mice.

Conclusions

Our data suggest that FliC-treated mice develop an SS-like phenotype. Our model may elucidate the relationship between commensal bacteria and SS.

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