Objective To investigate the expressions of ubiquitin-proteasome markers，including E2-14K，MAFbx，MuRF-1，and nuclear factor-κB（NF- κB） p50，in diaphragm of COPD rats，and their relationship with IL-17 level in diaphragm and serum in order to elucidate the potential mechanism of diaphragm atrophy. Methods Thirty healthy adult male SD rats were randomly divided into a model group （n=18） and a normal control group （n=12）. The COPD rat model was established by instillation of lipopolysaccharide （LPS） and exposure to cigarette smoke for 28 days. The protein levels of E2-14K，MAFbx，MuRF-1，and NF-κB p50 in diaphragm were measured by Western blot. The concentration of IL-17 in serum and diaphragm was measured by ELISA. Results Western blot showed that the protein expressions of E2-14K，MAFbx，MuRF-1，and NF-κB p50 in diaphragm increased significantly in the COPD model group compared with the normal control group （0.96±0.12 vs. 0.53±0.09，0.99±0.10 vs. 0.53±0.08，0.95±0.08 vs. 0.51±0.16，1.11±0.10 vs. 0.64±0.50，respectively，Plt;0.01）. The IL-17 level in serum and diaphragm was significantly higher in the COPD group than the control group. The expression of NF-κB p50 was positively correlated with E2-14K，MAFbx，and MuRF-1 expressions （r=0.82，0.92，0.86，respectively，Plt;0.01）. Both in serum and diaphragm，IL-17 level was positively correlated with the percentage of neutrophils，levels of NF-κB p50，E2-14K，MAFbx，and MuRF-1 expressions（all Plt;0.01）. The IL-17 levels in serum and diaphragm were also positively correlated each other （r=0.84，Plt;0.01）. Conclusions The results show that the ubiquitin-proteasom pathway，the NF-κB pathway and IL-17 are up-regulated in diaphragm of COPD rats .These alterations may contribute to diaphragm atrophy in COPD.
Objective To investigate the influence of proteasome inhibitorMG-132 on inflammatory factors in COPD rats and its potential mechanism. Methods The COPD rat model was established by instillation of lipopolysaccharide and exposure to cigarette smoke. Then the rats were randomly divided into 4 groups( n = 12 in each group) , ie. a COPD model group, a COPD + MG-132 low concentration group ( 0. 05 mg·kg- 1·d - 1 ) , a COPD + MG-132 high concentration group( 0. 1 mg· kg- 1 · d - 1 ) , and a normal control group. The rats were injected intraperitoneally with different dose of MG-132 or normal saline. After 1 week and 4 weeks, 6 rats in each group were sarcrificed. Then the following parameters were determined including histopathological changes of lung tissue, and the concentrations of IL-1β, IL-6, IL-8 in serum and diaphragm via ELISA. Results The lung histopathological examination showed obvious emphysema and inflammatory infiltration in the COPD rats. These pathological changes were obviously ameliorated in two MG-132 treatment groups. The IL-1β, IL-6, and IL-8 levels in serumand diaphragmin the COPD model group were all significantly increased from1 week and 4 week than those in the normal control group( P lt;0. 05) .MG-132 down-regulated the expression of these inflammatory factors in a time-and dosedependent manner. The IL-1β, IL-6, and IL-8 levels in serum and diaphragm in the MG-132 low concentration group and high concentration group were all decreased compared with the COPD model group ( P lt; 0. 05) . Conclusion COPD is a systemic inflammatory disease which can be inhibited by the proteasome inhibitor MG-132 through suppressing inflammatory factors.