Increase in acrolein-conjugated immunoglobulins in saliva from patients with primary Sjögren's syndrome

• Autoantibody activities were 3- to 5-fold higher in saliva from pSS patients.
• Autoantibody activities increased after acrolein treatment of saliva.
• Acrolein-conjugated amino acids were determined in immunoglobulins in saliva from pSS patients.
• Twenty-four amino acid residues were conjugated with acrolein at the variable region.

BackgroundWe previously reported that the level of protein-conjugated acrolein (PC-Acro), a marker of cell or tissue damage, was increased in saliva from patients with primary Sjögren's syndrome (pSS), and that the level of PC-Acro was well correlated with the severity of pSS.MethodsAcrolein-conjugated immunoglobulins were measured in saliva from pSS patients.ResultsThe activities of autoantibodies recognizing Sjögren's syndrome SSA (Ro) and SSB (La) proteins in saliva from pSS patients were approximately 3- to 5-fold higher than those from control subjects. We also found that autoantibody activities recognizing SSA (Ro) and SSB (La) proteins increased after acrolein treatment of saliva from control subjects. When an antibody against human serum albumin was treated with acrolein, the ability to recognize albumin was reduced but the ability to recognize other proteins was increased. Twenty-four and eleven kinds of acrolein-conjugated amino acids were found at the variable and constant regions of peptides, respectively, obtained from the immunoglobulins in saliva from pSS patients.ConclusionThe altered recognition patterns of immunoglobulins due to acrolein conjugation are at least partially involved in autoimmune diseases.