BackgroundAssociations between rheumatoid arthritis (RA) and reduced skeletal muscle have been studied, and we firstly reported myopenia independently predict one-year radiographic progression in RA. Myokine myostatin can negatively regulate skeletal muscle mass and promote osteoclast differentiation. However, there is no report about their relationships in RA patients. We firstly explored the relationship of serum myostatin and disease characteristics, as well as aggravated joint destruction during one-year follow-up.MethodsConsecutive RA patients were recruited from a real-world prospective cohort and completed at least one-year follow-up. Baseline serum level of myostatin was measured by enzyme-linked immunosorbent assay. Clinical data in RA patients as well as muscle index in both RA patients and healthy controls were collected. One-year radiographic progression as primary outcome was defined by a change in the total Sharp/van der Heijde modified score ≥0.5 units.ResultsTotally 344 RA patients (age 47.9 ± 12.5 years, 84.0% female) and 118 healthy control subjects (age 42.8 ± 11.3 years, 74.6% female) were recruited. Compared with healthy controls, RA patients showed a higher level of serum myostatin at baseline (3.241 ± 1.679 ng/ml vs. 1.717 ± 0.872 ng/ml, P<0.001), although lower appendicular skeletal muscle mass index (ASMI, 6.0 ± 0.9 kg/m2vs. 6.5 ± 1.0 kg/m2, P<0.001). In RA patients, those with high myostatin level showed a higher rate of radiographic progression than low myostatin group (45.3% vs. 18.6%, P<0.001). Furtherly, RA patients were stratified into four subgroups according to serum myostatin and myopenia. Compared with other three subgroups, RA patients with high myostatin overlapping myopenia had the highest rate of radiographic progression (67.2% vs. 10.3%-31.4%, P<0.001), as well as the lowest proportion of remission and the highest rate of physical dysfunction during one-year follow-up. After adjustment for confounding factors, high serum myostatin (AOR=3.451, 95%CI: 2.016-5.905) and myopenia (AOR=2.387, 95%CI: 1.416-4.022) at baseline were risk factors for one-year radiographic progression, especially for those with high myostatin overlapping myopenia (AOR=10.425, 95%CI: 3.959-27.450) as the highest-risk individuals among four subgroups. Significant synergistic interaction effect was observed between high myostatin and myopenia on one-year radiographic progression (AP=66.3%, 95%CI: 43.2%-89.3%).ConclusionMyostatin is a novel predictor of aggravated joint destruction in RA patients which has synergistic interaction with myopenia for predicting value.

Background: Although antinuclear antibodies (ANAs), anti-SSA and anti-Ro52, are present in immunoglobulin preparations, it is unknown whether intravenous immunoglobulin (IVIG) therapy influences the testing of serum autoantibodies in patients with connective tissue diseases (CTDs). The present study aimed to investigate the dynamic change over time of serum ANA-related autoantibodies in patients with CTDs receiving IVIG therapy. Methods: Serum ANA-related autoantibodies were monitored in two patients with CTD before IVIG therapy and at different times after therapy. These autoantibodies were tested in different batches of immunoglobulin preparations from seven pharmaceutical companies. Results: One patient developed a new ANA pattern (cytoplasmic dense fine speckled pattern, AC-19) just after IVIG therapy. Both patients developed de novo positivity for AMA-M2 and anti-SSA, but returned negative 1 month after IVIG therapy. The residual liquid in patients' immunoglobulin preparations showed positive ANAs with a high titer of AC-19 (1:640), a low titer of the nuclear fine speckled pattern (AC-4, 1:80), positive AMA-M2, and positive anti-SSA. ANA-related autoantibodies were tested in 16 batches of immunoglobulin preparations and all had positive ANAs with two patterns: AC-19 (1:640 or 1:320) and AC-4 (1:80). AMA-M2 and anti-SSA were positive in 100% of the batches. Conclusion: Our study highlights high-titer AMA-M2 autoantibodies in immunoglobulin preparations and suggests their transient transfer into a patient's circulation via IVIG therapy. To avoid incorrect clinical decisions based on postinfusion antibody titers, our data recommend retesting 1-2 months after high-dose IVIG immunomodulatory treatment.

目的探讨抗突变型瓜氨酸波形蛋白（MCV）抗体在类风湿关节炎（RA）诊断中的应用。方法前瞻性纳入RA患者,分别采用散射比浊法检测血清RF、ELISA检测抗环瓜氨酸肽（CCP）抗体和抗MCV抗体。若抗体水平升高但不超过3倍正常上限定义为低滴度阳性,若超过3倍正常上限定义为高滴度阳性。结果共纳入148例RA患者,RF、抗CCP抗体和抗MCV抗体的阳性率分别为72.3%、74.3%和77.7%,高滴度阳性率分别为52.7%、54.7%和65.5%,其中抗MCV抗体高滴度阳性率明显高于RF和抗CCP抗体（均P ＜0.05）。41例RF阴性的RA患者中,抗MCV抗体阳性率为46.3%。24例RF和抗CCP抗体均阴性的RA患者中,抗MCV抗体阳性率为33.3%,其中低滴度阳性的患者占8.3%,高滴度阳性者占25.0%。22例RF或抗CCP抗体至少1个低滴度阳性且均无高滴度阳性的患者中,抗MCV抗体低滴度阳性和高滴度阳性的患者分别占9.1%和59.1%。结论抗MCV抗体对诊断RA尤其是血清学阴性的患者有一定的补充价值。