Elevated Serum Activin A In Chronic Obstructive Pulmonary Disease With Skeletal Muscle Wasting

ObjectiveChronic obstructive pulmonary disease?COPD?is a chronic and progressive disease characterized by incompletely reversible airflow limitation.COPD does not only affect the lungs,but also can affect the skeletal muscles,cardiovascular system and digestive system^[1].As an important extrapulmonary effect of COPD,20-30%of patients with moderate to severe COPD have skeletal muscle atrophy^[2],some patients with COPD have early skeletal muscle dysfunction,and throughout the entire course of COPD disease.Muscle wasting contributes to the reduced quality of life and the increased mortality in COPD.Previous studies have found that activin A?Act A?activates skeletal muscle atrophy in cachectic mice by binding to activin receptor IIB?Act RIIB?.Serum Act A can be used as a detection indicator to assess skeletal muscle degradation.However,there are no reports on the study of serum Act A levels to assess the degree of skeletal muscle degradation in COPD patients.MethodsIn present study,we selected 78 patients with stable COPD and 60 age-matched healthy people from the physical examination center for the study.In the selection of the research objects,we excluded the subjects with higher inflammation levels in the body and airways through the examination of blood routine,C-reactive protein?CRP?and Fractional exhaled nitric oxide?FeNO?,cases of intravenous hormone use and acute exacerbations in the short term are excluded too.All subjects were tested for lung function,FeNO test,blood routine,CRP,and arterial blood gas analysis.In the study,we detect the serum levels of Act A via Enzyme linked immunosorbent assay?ELISA?assay,which also used to determine expression of circulating TNF-?levels.The comparison between Act A and Tumor Necrosis Factor-??TNF-??in the COPD group and the healthy group were compared,and the correlation analysis between abnormal Act A and TNF-?was made.We used anthropometry to obtain data about all subjects,and the Skeletal Muscle Mass?SMM?is calculated from the confirmed formulas,and according to specific criteria to determine whether skeletal muscle atrophy and the degree of atrophy.We used Dualenergy X-ray absorptiometry?DEXA?to provide Fat-free body Mass?FFM?.Moreover,Fat-free mass index?FFMI?was derived from FFM normalized to body surface area.Calculate the BMI index of all objects by formula.Finally,the correlation analysis of serum Act A level with SMM,FFMI and BMI.ResultsThe FEV1pred?%?and FEV1/FVC?%?of the COPD group were significantly lower than those of the control group by Pulmonary function test.Compared to the healthy controls,COPD patients had up-regulated Activin A and Tumor Necrosis Factor-??TNF-??expression.Elevated activin A level is positively correlated with TNF-?expression.The BMI index of the COPD group decreased compared with the control group via caculation.Total SMM and FFMI were significantly decreased in COPD patients.Furthermore,serum Activin A expression in COPD patients were negatively associated both with SMM and with FFMI and with BMI.ConclusionThe expression of serum Act A in COPD patients was significantly up-regulated,and the increase of serum Act A was related to TNF-?.The muscle mass index SMM,FFMI and BMI of COPD patients were significantly reduced,and had a negative correlation with the expression level of Act A in serum.Given the previous knowledge,we speculated that Activin A contributed to skeletal muscle wasting in COPD.