The Clinical Significance Of Serum Resistin Levels In Patients With Myasthenia Gravis

Objective To detect serum resistin levels in patients with myasthenia gravis(MG) and assess its clinical significance.Methods Serum resistin levels of the 102 patients with MG and 58 sex- and age-matched healthy controls were detected using enzyme linked immunosorbent assay(ELISA). At the same time, anti-acetylcholine receptor(ACh R) antibodies and anti-muscle specific tyrosine kinase(Mu SK) antibodies were detected using cell-based immunofluorescence assay(CBA), and quantified antibody levels into 0~4 grades. It was considered to be positive when its grade was greater than or equal to 1. The 102 patients with MG were divided into four groups: generalized myasthenia gravis(GMG) group(58 subjects), ocular myasthenia gravis(OMG) group(44 subjects that had not progressed to GMG within the first 2 years of the disease course), as well as groups MG with or MG without thymoma. Before treatments started we collected the basic clinical data of the participants, and assessed activities of daily living(ADL) scores at the time of serum sample collection. Serum resistin levels of 6 patients were dynamically monitored before and after immunosuppressive therapy. Finally we analyzed the characteristics of serum resistin levels in patients with sub-types of MG, and the relationship between serum resistin levels and the clinical data.Results 1. By CBA, we found that in the 102 patients with MG, there were 92 patients with anti-ACh R-antibody and 10 patients without anti-ACh R-antibody, and there were not any patients with anti-Mu SK antibodies. 2. No remarkable difference was found between patients with MG and healthy controls in body mass index(BMI), glucose(GLU), triglyceride(TG), total cholesterol(TC), low density lipoprotein(LDL) or high density lipoprotein(HDL). 3. Comparing the different groups with each other and healthy controls, we found that serum resistin levels in 102 patients with MG were significantly higher than healthy controls(P<0.001). Different serum resistin levels among different MG subtypes: higher resistin levels were found in GMG-patients than OMG-patients(P=0.001) and healthy controls(P<0.001). However, no remarkably difference between OMG-patients or healthy controls was found(P=0.150). 4. The serum resistin levels in anti-ACh R-antibody-positive-MG patients and anti-ACh R-antibody-negative-MG patients didn't differ greatly(P=0.085); There were significantly higher serum resistin levels in anti-ACh R-antibody-positive-MG patients than healthy controls(P<0.001); but no prominent difference was found between anti-ACh R-antibody-negative-MG patients and healthy controls. 5. Comparing different sub-types with serum resistin levels in patients with MG, our research demonstrated results as followings. MG-patients with thymoma had noticeably higher serum resistin levels than both MG-patients without thymoma(P=0.010) and healthy controls(P<0.001). Meanwhile, the higher serum resistin levels existed in MG-patients without thymoma than controls(P<0.001). Then we compared the mean resistin levels in GMG-patients with thymoma with GMG-patients without thymoma, it was significantly higher with P=0.006. Serum resistin levels in OMG-patients with thymoma had no statistically significant difference with OMG-patients without thymoma(P=0.481); both GMG-patients with thymoma and GMG-patients without thymoma had prominently higher serum resistin levels than healthy controls'(P<0.001, P<0.001). But either OMG-patients with thymoma or OMG-patients without thymoma didn't have statistically significant higher serum resistin levels than healthy controls. 6. In order to explore the relationship between serum resistin levels and MG-ADL as well as anti-ACh R-antibody scores, we made a correlation analysis: the serum resistin levels of MG patients and MG-ADL scores had a significant relationship(r=0.352, P<0.001), but the serum resistin levels and the scores of anti-ACh R antibodies had no significant correlations in patients with positive anti-ACh R antibodies MG(r=0.136, P=0.189). In patients with positive anti-ACh R antibodies MG but not in patients with anti-ACh R-antibody-negative-MG, there were statistically significant correlations between serum resistin levels and MG-ADL scores(r=0.428, P<0.001; r=-0.164, P=0.687). In MG patients with thymoma and without thymoma, both significant correlations were found between serum resistin levels and MG-ADL scores(r = 0.471, P=0.008; r=0.267, P=0.023). 7. After treatment, the disease severity alleviated, and the ADL scores reduced remarkably(P=0.035). And the serum resistin levels in the 6 MG patients were detected before and after immunosuppressive therapy, and the later were statistically remarkably lower(P=0.031).Conclusion: 1. Serum resistin levels upregulated in MG patients, resistin may involve in the inflammatory process of MG. 2. There are significantly different serum resistin levels between different MG patients groups, resistin may become a biomarker of inflammatory activity and may predict the disease sub-types and development trend. 3. Serum resistin levels relate to the disease severity of MG patients, and might be a sign of complicated with thymoma status. 4. Resistin might be a therapeutic target of MG, and maybe become an indirect evaluation index of treatment efficacy.