| Background:Scar is a general term for the morphological and pathological change of normal tissues caused by various injuries,which seriously affects the physical and mental health of patients.Therefore,the prevention and treatment of scar is one of the research focuses in the medical field.In recent years,many components of the Renin-angiotensin system(RAS)were found to be involved in the fibrosis of multiple organs such as heart,liver and lung.And the application of Angiotensin converting enzyme inhibitor(ACEI)could improve the fibrosis process by inhibiting the Transforming growth factor-β1(TGF-β1)signaling pathway.The skin tissue also has an intact RAS system,and the expression of Angiotensin converting enzyme(ACE)is significantly increased in the abnormal scar.After skin damage,ACEI could be used to improve scar formation,but the relevant studies are only limited to the therapeutic level.The source of ACE during scar formation and the mechanism of ACE intervention to improve scar formation are still unclear.Objective:This study aimed to confirm the role of ACE in mouse scar formation,identify the source of ACE involved in scar formation(derived from bone marrow inflammatory cells or/and local skin tissue),and explore the potential mechanism of intervening ACE to improve scar formation in vivo and in vitro.Methods:1)After modelling,mice were randomly selected into groups and given relevant drugs or water(ACE levels were different among the groups).The effects of ACE on scar formation were evaluated by general observation,H&E and Masson staining.2)C57 and ACE KO mice with different levels of bone marrow ACE were constructed respectively by bone marrow transplantation technique,to investigate the effect of bone marrow derived ACE on mouse scar formation;Mice with no and normal expression of ACE in their skin were constructed with the same technique to explore the influence of skin-derived ACE on scar formation.3)In vitro,ACE inhibitor was used to treat fibroblasts.RT-PCR,Western Blot,flow cytometry and other methods were used to evaluate the fibrosis effect and detect the expression of TGF-β1 signaling pathway.In vivo,ACE inhibitor(Ramipril),hydrazine pyridazine,blank control and ACE KO groups were set up.After the same modeling treatment,scar tissue was collected.The expression of TGF-β1 pathway related proteins were detected by molecular biological methods,and the expression of ACE related peptides were detected by immunohistochemistry and ELISA.Results:1)Scar formation was significantly improved in ACE knockout or inhibitor-treated mice,and TGF-β1 expression was also lower in these scars(P<0.05).2)In mice with reduced ACE from either bone marrow or skin,dorsal scar formation was narrower,the width and area under the microscope were smaller(P<0.05),and the fibers in the scar tissue were more loosely and orderly arranged.The difference in ACE level also affected the distribution of inflammatory cells and the expression of some growth factors in the middle stage of wound healing.3)After ACE knockout or inhibitor treatment,cell proliferation was slowed down,the expressions of TGF-β1 and total collagen were decreased,and the expressions of pSmad2/3 and p-TAK1 were also significantly down-regulated(P<0.05).Scar tissues of ACE knockout or inhibitor treatment groups had lower p-Smad2/3,p-TAK1,α-SMA,collagen Ⅰ and collagen Ⅲ expression(P<0.05);There were also differences in the expression of ACE related peptides among all groups.Conclusion:1)Reduction of ACE levels during wound healing can improve scar formation in mice.2)Both ACE from bone marrow and local skin tissue are involved in the regulation of scar formation,and the reduction of ACE from either source can improve scar formation.3)The improvement of scar formation by ACE knockout or inhibitor treatment is mainly achieved by down-regulating the TGF-β1/Smad2/3 and TGF-β1/TAK1 signaling pathways in fibroblasts. |
PDF Full Text Request