Correlation btween IgG4, TGF-β1, CTGF and fibrosis in Hashimoto thyroiditis

Abstract

Objective To explore the correlation among serum immunoglobulin G4 (IgG4), transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF) and Hashimoto thyroiditis(HT) thyroid fibrosis. Methods Case-control study. A total of 159 patients with HT visiting the Wuhan Union Hospital were collected from May 2013 to March 2015. All patients were divided into IgG4 HT group (IgG4≥1.35 g/L, n=39) and non-IgG4 HT group (IgG4<1.35 g/L, n=120). The serum IgG4, TGF-β1 and CTGF were determined by enzyme-linked immunosorbent assays. The levels of serum thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) were measured by electrochemiluminescence immunoassay. Meanwhile, ultrasound of the thyroid gland was performed. Statistical analysis was performed by use of SPSS 17.0 software. The Mann-Whitney U test was used to compare two independent samples of non-normal distribution data, Fisher′s exact test was employed to analyze thyroid imaging differences, correlation test was performed to examine various correlations, multivariate Logistic regression analysis was used to evaluate thyroid fibrosis risk factors. Results Compared with that of non-IgG4 HT group, IgG4 HT group: TPOAb [(455.2±169.7) vs. (186.5±102.3), U=27.0, P=0.003], TgAb [(984.6±452.7) vs. (289.3±245.1), U=30.5, P=0.017], TGF-β1 [(1.45±0.97) vs. (0.30±0.22), U=119.0, P=0.035] and CTGF [(88.65±14.39) vs. (62.21±8.76), U=69.0, P=0.039] were significantly higher, thyroid ultrasound showed obvious fibrosis (35/4 vs. 32/88, χ2=48.03, P=0.000); significant positive linear correlation between IgG4 and TPOAb (r=0.719, P=0.000), CTGF and TGF-β1 (r=0.500, P<0.01) respectively. Logistic regression analysis indicated that all the serum IgG4, TPOAb, TGF-β1 and CTGF were independent risk factors of thyroid fibrosis [IgG4, odds ratio (OR)=1.968, P=0.014, 95%confidence interval (CI)=1.287-2.041; TPOAb, OR=2.537, P=0.012, CI=1.322-2.869; TGF-β1, OR=1.549, P=0.023, CI=1.105-1.498; CTGF, OR=1.185, P=0.046, CI=1.204-1.625]. Conclusion The highlevel of circulating antibodies, IgG4, TGF-β1 and CTGF were significantly associated with thyroid fibrosis, and were independent risk factors of HT fibrosis.(Chin J Lab Med, 2015, 38: 848-851) Key words: Hashimoto disease; Fibrosis; Immunoglobulin G; Transforming growth factor beta1; Connective tissue growth factor