AB1111 RELATIONSHIP BETWEEN SERUM ADENOSINE DEAMINASE LEVELS AND DISEASE ACTIVITY IN AUTOIMMUNE HEPATITIS
Authors: Jing Xie, Hua Wei, Xiaoxing Xiang
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Autoimmune hepatitis(AIH)<sup>[1]</sup> is a chronic liver inflammation mediated by autoimmune response, characterized by serum autoantibodies, high immunoglobulin G(IgG), and interface hepatitis histology, which can develop into cirrhosis and liver failure. Adenosine deaminase(ADA) is an enzyme involved in purine metabolism, which can catalyze the irreversible conversion from deoxyadenosine to deoxyinosine. As adenosine is an important immunoregulatory factor in the physiological microenvironment, ADA plays an important role in regulating the balance of the human immune system. Previous studies have reported the associations between ADA and disease activity in a variety of autoimmune diseases, such as systemic lupus erythematosus<sup>[2]</sup>, rheumatoid arthritis<sup>[3]</sup>and juvenile idiopathic arthritis<sup>[4]</sup>. <h3>Objectives</h3> To investigate the relationship between serum adenosine deaminase levels and disease activity in patients with autoimmune hepatitis. <h3>Methods</h3> Thirty patients with autoimmune hepatitis and 30 healthy individuals were included in the study. We enrolled 30 patients who met the simplified criteria suggested by the International Autoimmune Hepatitis Group. All of the cases had been diagnosed with AIH between 2013-2018 at Northern Jiangsu People's Hospital, Department of Gastroenterology or Rheumatology, and the diagnosis was confirmd by liver biopsy. Serum adenosine deaminase levels were measured by enzyme-coupled assay, and &gt;25U/L were determined to be high level 25U/L. <h3>Results</h3> The mean serum ADA levels were prominently higher in AIH patients than those in healthy controls (29.13 ± 8.70 U/L vs 14.50 ± 4.63 U/L, P &lt; 0.001). Serum ADA levels were &gt; 25 U/L in 70% AIH patients and in 0% healthy controls(P &lt; 0.001). Mean serum ADA levels were significantly increased in each stage of disease activity: 26.32 ± 8.78 U/L for mild patients, 31.33 ± 4.23 U/L for moderate patients and 37.20 ± 7.36 U/L for severe patients(P = 0.03). Correlation analysis showed that there was a positive association between serum ADA levels and disease activity (r = 0.43, P = 0.02). Receiver operating characteristic analysis showed that 38.5 U/L was the optimum cut-off point of ADA level for severe disease activity (sensitivity 60%, specificity 92%, area under the curve: 0.81). <h3>Conclusion</h3> The evaluation of serum adenosine deaminse level in patients with autoimmune hepatitis should be considered a useful biomarker in the monitoring of their disease activity. <h3>References</h3> [1] Hennes, E.M., et al., Simplified criteria for the diagnosis of autoimmune hepatitis. Hepatology, 2008. 48(1): p. 169-76. [2] Gao, Z.W., et al., Serum adenosine deaminase activity is increased in systemic lupus erythematosus patients and correlated with disease activity. Immunol Res, 2018. 66(2): p. 299-304. [3] Zamani, B., R. Jamali, and A. Jamali, Serum adenosine deaminase may predict disease activity in rheumatoid arthritis. Rheumatol Int, 2012. 32(7): p. 1967-75. [4] Doudkani-Fard, M., et al., Sensitivity and specificity of adenosine deaminase in diagnosis of juvenile idiopathic arthritis. Med J Islam Repub Iran, 2014. 28: p. 113. <h3>Disclosure of Interests</h3> None declared