Expression Of Apoptosis-related Proteins In Muscle Tissue Of Pressure Injury And Research Of Effects On Wound

ObjectiveTo observe the phenomenon of apoptosis and expression of related proteins in injured muscle tissue during the formation of pressure injury,and to explore the effects of TGF – beta 1 on wounds of the pressure injury.MethodsForty male Sprague-Dawley(SD)rats were divided into normal control group,3,5,7 and 9 compression groups according to the random number table,with 8 rats in each group.The pressure injury models on the gracilis muscle of hind limbs were established by using a way of cycle compression of ischemia/reperfusion(IR)magnet.One cycle consisted of 12 hours compression,followed by 12 hours of release.The 5,7,9compression groups were cut through and received pressure to 5,7,9 cycles after receiving 3 cycles.The normal control group did not receive any treatment.Muscle tissue specimens were harvested in the pressurized center at the end of the experiment(the same site for the normal control group),and then the rats were sacrificed.The hematoxylin-eosin(HE)staining was used to examine the changes of muscle tissue morphology.The Hoechst 33258 staining was used to evaluate the apoptosis of muscle tissue.The immunohistochemical staining was used to detect the dynamic change of Bcl-2 and Bax.Western Blot was used to detect the expression of Bcl-2,Bax,HSP 70 and TGF-β1.One-way analysis of variance(ANOVA)followed by LSD test was used to compare difference between means in more than two groups.Results1.HE staining showed that the compressed tissue appears different degrees of pathological degradation,and the change of tissue morphology was more serious with the increase of the compression cycle.2.Hoechst 33258 staining showed that the nuclei of compressed tissue showed condensed,compact morphology and granular fluorescence,and the number of apoptotic cells increased with the increase of the compression cycle.3.Immunohistochemical staining showed that compared with the normal control group,the protein level of Bcl-2 was lower and the protein level of Bax was higher,the detected immunoreactivity were distributed in nucleus and cytoplasm.4.Western Blot showed that compared with the normal control group,The protein level of Bcl-2 was significantly(gray value: 0.36±0.04 vs.0.17±0.03 、 0.13±003 、0.14±0.03、0.10±0.02,all P<0.05)with statistically significantly differences.The protein levels of Bax,HSP70 and TGF-β1 were significantly(gray value: Bax protein:0.67±0.07 vs.0.73±0.08、0.73±0.05、0.96±0.09、0.98±0.02,all P<0.05;HSP 70 protein:0.55±0.17 vs.0.74±0.14、0.87±0.19、1.28±0.20、1.78±0.21,all P<0.05;TGF-β1 protein:0.35±0.05 vs.2.99±0.16、2.79±0.17、2.34±0.19、1.44±0.16,all P<0.05;)with statistically significant differences.ConclusionApoptosis can be induced by ischemia reperfusion in pressure injury tissues.Apoptosis induced by heat shock protein 70 and apoptosis factors Bcl-2 and Bax may be involved in the formation of pressure injury.The high expression of TGF-β1 in pressure injury may affect wounds healing.This may provide molecular level scientific basis for clinical prevention and treatment of pressure injury.