Preventive Effects Of S1p1 Receptor Regulator On Radiation-induced Oral Mucositis And The Preliminary Exploration Of Its Target

Backgroundradiation-induced oral mucositis(ROM)is a frequent,acute and/or chronic oral mucosal damage,which is among the most common side effects associated with radiotherapy used for the treatment of cancers of the head and neck.The painful lesion is sometime so severe that the treatment has to be interputted,and even significantly reduce patient’s quality of life.Therefore,aggressive treatment of oral mucositis is an important part of cancer adjuvant therapy.S1PR1 for G protein-coupled receptors,which is expressed in adaptive immunity cells,innate immune cells and endothelial cells.The latest research shows that S1PR1 regulator may inhibit the activation state of S1PR1 of innate immune cells,adaptive immune cells or regulate activation state of S1PR 1 of endothelial cells,which can prevent progressive inflammatory immune response or reduce cytokine storm that is induced by radiation,and ultimately improve the organ microenvironment after radiation.Therefore,S1PR1 probably involve in the reconstruction of body’s tissues and organs through one of the links directly after radiation.The aims of present study are to establish an animal model of radiation-induced oral mucositis and to observe protective effect of the S1PR1 regulator,and thus evidences of nosogenesis,drug development and clinical treatment of ROM would be provided.ObjectiveThe purpose of this study was to evaluate the protective effect of S1PR1 regulator against radiation-induced oral mucositis in mice,and to approach the mechanism.Method1.To establish a mice model of ROM;By Experimental pathology of effects on tongue mucosa of radiation-induced oral mucositis,to observe the effect of different irradiation doses(16Gy,17Gy,18Gy),study the effect of prevention and treatment of different administration time and dosage of SIP receptor agonist FTY720(48h,36h,24h,12h,3h before irradiation)and(2h,6h,12h after irradiation),(2.5mg/kg,5.0mg/kg and 10mg/kg),and finally explore the optimal dosing regimen;then by the survival experiments,proliferation of keratinized epithelial cell,observation of tongue mucosa at different time points after exposure on FTY720 control mice,preliminary explore the FTY720 protection mechanism;Then we make a effect comparison between FTY720 and treatment agent of ROM which was reported in the literature.2.By experiment on ROM mice treated with S1PR1 specificity agonists CYM5442 and specificity antagonists NIBR-0213,observe the survival rate,change of weight for 30 days and tongue tissue analysis.Results1.The study on effects of S1P receptor agonist FTY720 in treating ROM mice.1.1 The establishment of the modle of ROM mice.Mice were sacrificed at 7 days after 17Gy irradiation on head and neck area and tounge tieeues were assayed by 1%toluidine blue staining and HE staining to observe the oral ulcer and pathological changes of tongue tissue.The proliferation of keratinocyte cell was detected by Ki-67 immunohistochemistry.Compared with the normal group,there were damaged epithelial structure and obvious ulcer on irradiation group,which can be referred to as the ROM mice.1.2 Protective effect of FTY720 on ROM and the optimal dosage regimen of FTY720.The provetion of FTY720(10mg/kg,Intraperitoneal adminietration,3hr,12hr,24hr before irradiation)on the 17Gy irradiated mices was significantly.1.3 The preliminary exploration of protection mechanism of FTY720 on ROM.FTY720 have significantly increased the survival rate of ROM mice.After 17Gy irradiation,the survival rate of control group was 28.57%and the FTY720 group(3hr,12hr,24hr before irradiation)were 75%,100%,100%;After 18 Gy irradiation,the control group were all dead after 11 days,the survival rate of FTY720 have reached 62.5%.There were significant differences between two groups.improve survival in mice.The proliferation of keratinocyte cell was detected by Ki-67 immunohistochemistry.The keratinocytes numbers per mm of tongue mucosa of FTY720 group and control group were 276.9±31.6,33.1±6.1.The FTY720 group was significantly higher than the control group.Through observation of the tongue mucosa on ROM mice wih or without FTY720 at different time points,understand mucosa’s pathological changes.2.Preliminary study on mechanism of action of S1PR1regulator in the treatment of ROM.S1PR1 specificity agonists CYM5442(20mg/kg,3 hr,12 hr and 24 hr before irradiation)have protected the epithelium of tongue mucosa and significantly improved the survival rate to 87.5%,100%and 100%;S1PR1 specificity antagonists NIBR-0213 also have the same effect.Explain S1PR1 may be main targets for the prevention and control of ROM.ConciusionS1PR1 regulator agent have protective effect on the ROM mice,S1PR1 may be the main target for treatment of the ROM.