Serum growth arrest-specific protein 6 levels are a reliable biomarker of disease activity in systemic lupus erythematosus.
OBJECTIVE
Growth arrest-specific protein 6 (Gas6) has been suggested to be a biomarker of disease activity in patients with systemic lupus erthematosus (SLE). We investigated the clinical significance of this protein in Korean SLE.


METHODS
Blood samples were collected from 150 SLE patients and 50 normal controls (NC). In addition, follow-up samples were collected from 50 SLE patients.


RESULTS
Serum Gas6 levels of SLE patients (43.01 ± 28.02 ng/mL) were higher than those of NC (20.15 ± 9.23 ng/mL, p<0.001). When evaluated sensitivity and specificity of the Gas6 for diagnosing SLE using ROC curves, the sensitivity and specificity were 72.7 % and 84 % with a cut-off value of 25.3 ng/mL. In the ROC analysis of Gas6, anti-dsDNA antibody, ESR, complement 3 and complement 4 to identify patients with active lupus, area under the curve (AUC) of Gas6 was highest with 0.763. Serum Gas6 levels were significantly higher in the patients with serositis (70.04 ± 30.85 ng/mL) and renal disorder (65.66 ± 32.28 ng/mL) compared to those without (41.88 ± 27.44 ng/mL, p=0.033, 40.3 ± 26.33 ng/mL, p=0.001, respectively). Gas6 levels were correlated positively with anti-dsDNA antibody (r=0.199, p=0.015), ESR (r=0.204, p=0.013) and SLEDAI (r=0.512, p<0.001). In addition, serum Gas6 levels were correlated negatively with hemoglobin (r= -0.165, p=0.043), lymphocyte count (r= -0.165, p=0.043), complement 3 (r= -0.343, p<0.001) and complement 4 (r= -0.316, p<0.001). Furthermore, change in serum Gas6 levels was correlated with change in SLEDAI levels in the SLE patients that were followed up (r=0.524, p<0.001).


CONCLUSIONS
These results suggest that serum Gas6 can be a reliable clinical marker for monitoring disease activity and treatment response in SLE.
Department of Rheumatology and BK21 Division of Cell Transformation and Restoration, Ajou University School of Medicine, San 5, Wonchon-dong, Yeongtong-gu, Suwon, South Korea, 443-721.
Hyoun-Ah
HA
Kim
Jin-Young
JY
Nam
Ja-Young
JY
Jeon
Jeong-Mi
JM
An
Ju-Yang
JY
Jung
Chang-Bum
CB
Bae
Chang-Hee
CH
Suh
D000328:Adult; D015415:Biomarkers / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000175:diagnosis / Q000276:immunology*; D008875:Middle Aged; D015203:Reproducibility of Results; D056910:Republic of Korea; D016896:Treatment Outcome; D000099255:Growth Arrest-Specific Protein 6
D015415:Biomarkers; D018836:Inflammation Mediators; D036341:Intercellular Signaling Peptides and Proteins; D000099255:Growth Arrest-Specific Protein 6