Clinical significance of autoantibodies against ubiquitin carboxyl hydrolase L1 epitopes in the screening and diagnosis of Sjögren syndrome

Abstract

Objective: To study the clinical significance of autoantibodies against different ubiquitin carboxyl hydrolase L1 (UCH-L1) epitopes in Sjogren syndrome (SS). Methods: The serum levels of different UCH-L1 epitope autoantibodies in 98 SS patients [SS group, 17 males and 81 females, aged (49.1±12.3) years] in the Fifth Affiliated Hospital of Zhengzhou University and Peking University People's Hospital from January 2017 to January 2020 and 37 healthy controls [control group, 6 males and 31 females, aged (46.3±5.8) years] were determined by enzyme-linked immunosorbent assay (ELISA). Three potential epitopes of UCH-L1 protein were analyzed and synthesized and anti-UCH-L1203-214 and anti-UCH-L158-69 antibodies were studied between the two groups. The levels of the two anti-UCH-L1 antibodies in the two groups were compared. The correlation between the levels of UCH-L1 antibodies and clinical data of SS patients were analyzed by Pearson correlation analysis. Results: The serum levels of anti-UCH-L1203-214 and anti-UCH-L158-69 antibody in SS patients were significantly higher than those in healthy controls (HCs) (anti-UCH-L1203-214: 108.2±54.3 vs 78.9±25.8, P<0.001, anti-UCH-L158-69: 86.8±33.3 vs 60.4±21.5, P<0.001). The positive rates of anti-UCH-L1203-214 and anti-UCH-L158-69 antibodies in serums of SS patients were 27.6 % (27/98) and 25.5% (25/98), and those in HCs were 2.7%(1/37) and 5.4 %(2/37), respectively. In SS patients with positive serum anti-UCH-L158-69 antibody, the levels of IgG, γ globulin and rheumatoid factor (RF) and anti-SS-related antigen B (anti-SSB) antibody positive rate were all significantly higher than those in patients with negative antibody (all P<0.05). In SS patients with negative antinuclear antibody (ANA), anti-RNA binding protein (anti-RNP) antibody, anti-SS-related antigen A (anti-SSA) antibody and anti-SSB antibody, the positive rates of anti-UCH-L1203-214 antibody was 32.1%(9/28), 27.2%(25/92), 36.4%(12/33), 28.6%(18/63), respectively; and the positive rates of anti-UCH-L158-69 antibody was 21.4%(6/28), 30.4%(28/92), 30.3%(10/33), 20.6%(13/63), respectively. The level of serum anti-UCH-L1203-214 antibody in SS patients was positively correlated with the IgA level (r=0.21, P=0.024). The level of anti-UCH-L158-69 antibody in SS patients was positively correlated with the levels of γ-globulin, IgG and RF (r=0.35, 0.33, 0.32, all P<0.01). Conclusion: Autoantibodies against UCH-L1 epitopes are correlated with some clinical parameters of SS patients, which is of promising significance in the screening and diagnosis of SS.