Down-regulated resistin level in consequence of decreased neutrophil counts in untreated Grave's disease

Abstract

Resistin, belongs to cysteine-rich secretory protein, is mainly produced by circulating leukocytes, such as neutrophils monocytes and macrophages in humans. To date, few but controversial studies have reported about resistin concentrations in hyperthyroid patients, especially in Graves' disease (GD). We undertaked a controlled, prospective study to explore the serum resistin concentration in GD patients before and after -MMI treatment. In addition, we also investigated the main influencing factor on serum resistin level and discuessed the potential role of serum resistin plays in GD patients. 39 untreated GD (uGD) patients, including 8 males and 31 females, were enrolled in our investigation. All of these patients were prescribed with MMI treatment, in addition to 25 healthy controls. Anthropometric parameters and hormone assessment were measured. Enzyme-linked immunosorbent assay was used to detect serum resistin concentration in different stages of GD patients. Furthermore, neutrophil cell line NB4 with or without T3 treatment to detect the effect of thyroid hormones on resistin expression. The serum resistin level and neutrophil counts in untreated GD patients were significantly declined. And all of these parameters were recovered to normal after MMI treatment in ethyroid GD (eGD) and TRAb-negative conversion (nGD) patients. Resistin concentration exhibited a negative correlation with FT3 and FT4, but a positive correlation with absolute number of neutrophiles in uGD patients, whereas did not correlate with thyroid autoimmune antibodies and BMI. Neutrophile cell line, NB4, produced decreased expression of resistin when stimulated with T3. Our study showed a decrease of serum resistin level in GD patients and we suggested that the serum resistin might primarily secreted from circulating neutrophils and down-regulated by excessive thyroid hormones in GD patients.

Keywords: Graves’ disease; T3; neutrophils; resistin.

Figure 1. Serum resistin concentrations in GD patients and healthy controls

Serum resistin level in untreated GD patients (n=39) decreased compared with and healthy controls(m=25). The resistin level in uGD patients increased to normal after normalization of thyroid hormones (eGD) and TRAb negative-conversion. Serum resistin was measured by enzyme-linked immunosorbent assay (ELISA). All data were presented as mean ± SEM. * : compared with uGD.* P<0.05.

Figure 2. The correlation of serum resistin with neutrophil counts

A. Circulating neutrophils counts and proportion in uGD, eGD, nGD and hCD. B. The serum resistin level in uGD patients is positive correlated with circulating neutrohpils. * P<0.05.

Figure 3. The effect of thyroid hormone T3 (100ng/ml) on resistin expression in neutrophil cell line NB4

The mRNA A. and protein B. expression of resistin in NB4 is suppressed upon T3 treatment in a time-dependent manner.*: compared with Day0. * P<0.05* * P<0.01.