Autoantibody to MDM2: A potential serological marker of primary Sjogren’s syndrome

// Yuan Liu 1,* , Xining Liao 2,* , Ying Wang 3,* , Shiju Chen 1 , Yuechi Sun 1 , Qingyan Lin 1 and Guixiu Shi 1 1 Department of Rheumatology and Clinical Immunology, The First Affiliated Hospital of Xiamen University, Xiamen, China 2 Medical College, Xiamen University, Xiamen, Fujian, China 3 Department of Endocrinology, The ChengGong Hospital Affiliated to Xiamen University, Xiamen, Fujian, China * Yuan Liu, Xining Liao and Ying Wang contribute equally to this study Correspondence to: Guixiu Shi, email: // Keywords : primary Sjogren’s syndrome; anti-MDM2 autoantibody; biomarker;Immunology and Microbiology Section; Immune response; Immunity Received : September 27, 2016 Accepted : January 17, 2017 Published : January 28, 2017 Abstract Introduction: Primary Sjogren’s Syndrome (pSS) is one of the autoimmune diseases characterized by polyclonal autoantibody production. The human homologue of the mouse double minute 2 (MDM2) is an important negative regulator of p53. Our previous study indicated that autoantibody to MDM2 can be detected in systemic lupus erythematosus patients. The purpose of this study is to study anti-MDM2 autoantibody in pSS patients. Methods: Anti-MDM2 autoantibody in sera from 100 pSS patients and 74 normal controls was investigated by ELISA. Positive samples were further confirmed by western blotting. Expression of MDM2 in labial gland tissue from pSS patients and normal controls was checked by immunohistochemistry. The difference in clinical characteristics and laboratory findings between anti-MDM2 positive and anti-MDM2 negative pSS patients was analyzed. Results: The presence of anti-MDM2 autoantibody in pSS patients was 21.0%, significantly higher than normal controls (5.40%). MDM2 was overexpressed in labial gland from pSS patients. pSS patients with positive anti-MDM2 were characterized by longer disease duration and more lymphocytes focal gathering in labial gland. Prevalence of anemia, thrombocytopenia and anti-SSB was significantly higher in pSS patients with anti-MDM2 autoantibody. Titer of anit-MDM2 was negatively associated with hemoglobin level, platelet count, complement 3 level and complement 4 level, positively associated with European Sjogren’s syndrome disease activity index (ESSDAI) and level of IgG. Conclusions: Anti-MDM2 autoantibody may be used as a potential serological biomarker in pSS disease activity evaluation. Study on the role of anti-MDM2 or MDM2 in pSS may help us know the pathogenesis mechanism of pSS better.