Emodin Modulates Hypertrophic Scar Formation And Fibrosis

Backgroud: A hypertrophic scar(HS)is the most common complication of skin injury,which manifest as raised,red,inflexible lessions,and is responsible for serious functional and cosmetic problems.HS is pathologically a significant skin fibrotic disease and has negative impacts on patient appearance,skeletal muscular functions,and quality of life in general,resulting in disfigurement and dysfunction.To date,the etiological mechanism of hypertrophic scar formation and fibrosis is poorly understood,and few effective and specific therapeutic approaches are utilized in clinical practice.It is ell known that wound healing consists pathologically of inflammatory,proliferative,and remodelling phases.When the inflammatory phase lasts much longer,different sub-populations of inflammatory cells recruited,HSs will be probably formed.And it is also well known that macrophages play pivotal roles in the transition from inflammatory to proliferative phases,in which they coordinate and sustain the wound-healing process,and ultimately control the degree of scar formation.Emodin is a major component of the widely used Chinese herb,rhubarb.It has been demonstrated that emodin may inhibit mechanical stretch-induced HS inflammation by attenuating inflammatory cell recruitment and suppressing the secretion of inflammatory cytokines.Objective: Suppressing effects of emodin on hyperstrophic scars and their molecular mechanisms are investigated..Methods: We first conducted in vitro experiments to investigate the modulating effect of emodin to macrophages polarization to M1/M2 in vitro.After that we established hypertrophic scar rat-tail models,curving the tails of the rats and fixing them.It could load sustaining stretch to the wound to create the hypertrophic scar.To simulate the internal environment of wound healing and hypertrophic scar formation and fibrosis,we implanted polyvinylalcohol(PVA)sponge on the rat dorsum subcutaneously and collected the exudates and cells to study.We observed the effect of emodin on hypertrophic scars formation and fibrosis by general observation and histopathological sections staining.And then we collected the cells from the PVA implants and analysed them.We used mass spectrometry,flow cytometry,western blotting and real-time PCR to investigate the molecular mechanism.Results: First we validated that emodin suppressed macrophages polarization to both M1 and M2 in vitro.By general observation,we found that emodin could attenuate the level of inflammatory response in the early stage of wound healing and the degree of hypertrophic scar formation in vivo.Histopathological sections staining confirmed that rat tail hypertrophic scar model was a reliable model of investigation and study of hypertrophic scar,which can effectively mimic hypertrophic scars in human skin.Meanwhile,it also validated that emodin could repress the level of inflammatory response and the degree of hypertrophic scar formation.By flow cytometry analysis of the collection of PVA sponge implanted exudates,we found that compared with the control group rats,the rats in experimental group showed a decreased total number of macrophages,reduced polarization rate of M1 and M2 macrophage.The population of M1 and M2 macrophages was further reduced.The results of western blotting and Real-time PCR confirmed that emodin could suppress the expression level of TGF-? and inhibit the TGF-? pathway and Notch pathway.Conclusion: Emodin is an workable therapeutic regimen to hypertrophic scar,which can effectively suppress hypertrophic scar formation.The results of molecular biological mechanism substantiate our hypothesis that emodin attenuates hypertrophic scars formation and fibrosis by modulating macrophage polarization to M1/M2,which was through regulating the Notch pathways and TGF-?.