Introduction Idiopathic inflammatory myopathies (IIMs) are autoimmune, systemic diseases that affect skeletal muscles. The causes are not fully understood. IIMs present with proximal weakness, elevated muscle enzymes (primarily creatine phosphokinase, or CPK), and multiorgan involvement, often pulmonary. Muscle tissue shows leukocyte infiltration, and specific autoantibodies are present. We aimed to investigate the possible association between the IL1B rs16944 polymorphism and the risk of developing IIMs. Methods DNA was extracted from blood samples collected from 57 patients with IIMs and 50 healthy controls. The IL1B rs16944 polymorphism was analyzed. Myositis-specific autoantibodies (MSAs), myositis-associated autoantibodies (MAAs), and antinuclear antibodies (ANAs) were determined. Results The IIM subtypes in our patients were dermatomyositis (DM), polymyositis, amyopathic DM, juvenile DM, cancer-associated myositis, scleromyositis, and antisynthetase syndrome. The three most frequent were DM (47.4%), polymyositis (22.8%), and cancer-associated myositis (17.5%). Regarding ANAs, the three most frequent patterns in patients were AC-4 (nuclear fine speckled, 40%), AC-21 (cytoplasmic reticular/AMA, 10%), and AC-19 (cytoplasmic dense fine speckled, 8.6%), while 15.7% were negative. About myositis autoantibodies, the most frequent MSAa in IIMs were anti-SAE1 (12.5%), anti-MDA5 (10.7), and anti-TIF1g (10.7%). The most common MAAs were as follows: anti-Ro52 (30.4%), anti-Ku (14.3%), and anti-PM100 (5.4%). Analysis of the IL1B polymorphism rs16944 revealed a significant association with susceptibility to IIMS in the codominant model (CC vs. CT, OR = 4.6136, 95% CI: 1.83–11.65, p = 0.0012), dominant model (OR = 3.432, 95% CI: 1.47–7.98, p = 0.0044) and overdominant model (OR = 3.587, 95% CI: 1.58–7.92, p = 0.0021). Considering the female group, between cases and HC, the codominant (CC vs. CT), the dominant, and the overdominant genetic models presented significant differences ( p = 0.0015, 0.0038, and OR = 4.5043, 95% CI: 1.59–12.68, p = 0.0044, respectively). Also, a significant association could be observed with DM, polymyositis (PM), DM+PM, juvenile DM, amyopathic DM, antisynthetase syndrome (ASyS), and cancer-associated myositis (CAM). Enzyme levels of CPK presented significant differences in our IIMs patients. The rs16944 polymorphism is significantly associated with various clinicopathological characteristics. Conclusion This study has, for the first time, revealed an association between the IL1B rs16944 CC (codominant and dominant models) and CCTT (overdominant) genotypes and the IIMs phenotype (OR = 4.6136, 3.4232, and 3.5387, respectively).
Torre et al. (Wed,) studied this question.