Possible involvement of EBV-mediated α-fodrin cleavage for organ-specific autoantigen in Sjogren's syndrome

A cleavage product of α-fodrin may be an important organ-specific autoantigen in the pathogenesis of Sjogren's syndrome (SS), but the mechanisms of α-fodrin cleavage remain unclear. Since EBV has been implicated in the pathogenesis of SS, we determined whether EBV activation could induce the SS-specific 120-kDa autoantigen α-fodrin. ZEBRA mRNA expression, a marker for activation of the lytic cycle of EBV, was found in the salivary gland tissues from SS patients, but not in those from control individuals. ZEBRA-expressing lymphoid cells were also found in the SS glands in double-stained immunohistochemistry. Furthermore, a significant link between production of Abs against 120-kDa α-fodrin and reactivated EBV Ag was found in sera from patients with SS, but not in those from control individuals. EBV-activated lymphoid cells showed specific α-fodrin cleavage to the expected 120-kDa fragments in vitro. Pretreatment with caspase inhibitors inhibited cleavage of α-fodrin. Thus, an increase in apoptotic protease activities induced by EBV reactivation may be involved in the progression of α-fodrin proteolysis in the development of SS.