MRNA Expression Of PPARa And Serum TNFa,IL-8,hsCRP Level Studies In COPD Patients With Vastus Lateralis Muscle Atrophy

Objective To study the peroxisome proliferator-activated receptor-a (PPARa)mRNA expression in the vastus lateralis muscle and serum TNFa,IL-8,hsCRP levels in stable patients with chronic obstructive pulmonary disease (COPD) to explore the pathogenesis of COPD muscle atrophy.Methods 30 cases selected and divided into healthy control group (10 cases),cachectic COPD group (10 cases),noncathectic COPD group (10 cases), first of all, pulmonary function,body composition and blood gas analysis were tested. Then, serum IL-8,TNFa were detected by enzyme-linked immunosorbent assay( ELISA) method and hsCRP were detected in our hospital biochemistry laboratory. Finally, 50mg vastus lateralis muscle samples were taken by fine-needle aspiration biopsy from all enrollments and adjusted the reaction conditions of real-time fluorescence quantitative reverse transcript -poly merase chain reaction (RT-PCR) which was established to examine the relative PPARa mRNA expression levels in the vastus lateralis muscle.Results 1. the characteristic of COPD patients with vastus lateralis muscle atrophy:cachectic COPD group patients suffered from COPD were longer than noncachectic COPD group (p < 0.01). Body weight, body mas- index, fat free mass and fat free mass-index declined in the cachectic group compared to the healthy control and noncachectic group (p < 0.01, for each); fat mass and fat mass-index declined in the cachectic group compared to the healthy control group (p < 0.01, for each); body mas-index declined in the noncachectic group compared to the healthy control group(p < 0.05). There were differences of lung function by pairwise comparisons among the healthy control, cachectic and noncachectic group, FEV1% PRE, FEV1/FVC% and FVC% PRE were statistically significant (p < 0.01, for each), and those reduced in the cachectic group compared to the healthy control and noncachectic groups and also reduced in the noncachectic group compared to the healthy control. PO₂ was lower in the cachectic group and noncachectic group compared to the healthy control (p < 0.01, for each).2. Blood inflammatory factor levels: there were no differences of serum hsCRP among the three groups, There were differences of serum IL-8 and TNFαlevels by pairwise comparisons among the healthy control,cachectic and noncachectic group (p < 0.01 for each), serum IL-8 and TNFαlevels were enhanced in the cachectic group compared to the noncachectic and healthy control groupand were enhanced in the noncachectic group compared to the healthy control group.3. Explored the real-time fluorescence quanitiative RT-PCR: By exploring the conditions of real-time fluorescence quantitative reverse transcript -poly merase chain reaction,detected the PPARa mRNA and GAPDH real-time quantitative RT-PCR reaction systems were cDNA 3.0μl; TaqDNA polymerase 0.1U/μl, 1.0μl; each primer of upstream and downstream 1.0μl; One-step RT-PCR Kit 25μl; the total reaction volumes were 50μl. Amplification conditions: pre-denaturation at 94℃for 5 minutes, 33 cycles of denaturation at 94℃for 45seconds; anneal at 63℃for 45seconds; extension at 72℃for 45seconds, overtime extension at 72℃for 5minutes.4. PPARa mRNA expression: PPARa mRNA expression in the vastus lateralis muscle were: healthy control group0.82±0.15; cathectic COPD group 0.44±0.12; noncathectic COPD group 0.69±0.14; total COPD 0.56±0.18. Compared with the healthy control group and noncathectic COPD group cathectic COPD group had statistically significant difference( p <0.01, for each ) and cathectic COPD group PPARa mRNA expression was reduced;There were no statistically significant difference between noncathectic COPD group and healthy control group(p>0.05), but noncathectic COPD group showed a downward trend in expression of PPARa mRNA compareed to healthy group; it was different between total COPD and healthy control group(p <0.01) and the PPARa mRNA was lower in total COPD.5. Relationships: PPARa mRNA expression was positively correlated with FFMI and BMI (r = 0.586, r = 0.626; p <0.01); negatively correlated with serum TNFa and IL-8 (r =- 0.618, r =- 0.690; p <0.01); positively correlated with FEV1% PRE and FEV1% FVC (r = 0.574, r = 0.613; p <0.01).Conclusion This study shows that COPD patients combined with skeletal muscleatrophy suffered from COPD for long years and with clinical features such as body composition changes ,lung function decreasement and chronic hypoxemia, etc. vastus lateralis muscle PPARa mRNA expression level was decreased in total COPD and COPD combined with skeletal muscle atrophy patients and it was trended to reduce in noncachectic COPD patients. while serum TNFa,IL-8 were increased in all cachectic and noncachectic COPD patients. The PPARa mRNA expression was positively correlated with FFMI and BMI; negatively correlated with TNFa and IL-8; positively correlated with FEV1% PRE and FEV1% FVC. To sum up that the downward PPARa mRNA expression level participated in COPD systemic and chronic inflammatory response, not only involved in the lung maked the further decline in lung function but also skeletal muscle lead to the occurrence of skeletal muscle atrophy and played an important role in COPD skeletal muscle atrophy.