Correlation of the levels of interleukin-17 and its receptor with myasthenia gravis

Abstract

Objective To investigate the correlation of plasma interleukin (IL)-17 level and IL-17 receptor (IL-17R) expression in the thymus of patients with myasthenia gravis (MG). Methods The blood samples of 63 patients (38 with glucocorticoid treatment, 25 with thymus removal) who admitted to Henan Provincial People's Hospital between 2010 and 2014 were collected at three different stages: pre-treatment, 1 week post-treatment and 1 month post-treatment. The blood samples of 42 healthy controls were also collected. Enzyme linked immunosorbent assay was used to evaluate the levels of IL-17 in plasma. Twenty-five thymus tissues from MG patients and another 12 thymus tissues from patients with congenital heart disease who had surgery therapy were also collected. Reverse transcription polymerase chain reaction was used to evaluate the mRNA levels of IL-17R. The possible correlation between the expression of IL-17 and IL-17R with MG was analyzed. Results Before treatment, the levels of IL-17 in the plasma were much higher in all the MG patients (both ocular and generalized) when compared to the healthy controls (controls (3.2±0.7) pg/ml, MG patients (8.5±1.7) pg/ml, t=2.450, P 0.05, compared to the healthy controls). In the surgery therapy cases, the IL-17 levels were also reduced after the thymus removal (pre-surgery (8.8±1.4) pg/ml, 1 week after surgery (5.3±0.7) pg/ml, t=1.950, P<0.05; 1 month after surgery (3.0±0.4) pg/ml, t=2.683, P<0.01). In the thymus tissues of the MG patients, the mRNA levels of IL-17R were much higher than that of the controls (relative level 2.31 folds, t=2.682, P<0.01). Meanwhile, a positive correlation was found between the plasma IL-17 levels and the relative IL-17R levels in thymus tissues (r=0.945 4, P<0.01). Furthermore, IL-17 was positively correlated with quantitative myasthenia gravis scores (QMGS) either pre-treatment (r=0.798 1, P<0.01) or post-treatment (r=0.906 5, P<0.01). And IL-17R was positively correlated with QMGS pre-treatment (r=0.775 5, P<0.01). Conclusions IL-17 is increased in the plasma of MG patients (both ocular and generalized), and is decreased upon the glucocorticoid treatment or surgery therapy, suggesting that it can be used as a parameter to determine the therapeutic effects. IL-17R is increased in the thymus tissues of MG patients, suggesting that it can potentially be used as a pathological diagnosis parameter. Key words: Myasthenia gravis; Interleukin-17; Receptors, interleukin-17; Adrenal cortex hormones; Case-control studies