Research And Analysis On The Model Of Systemic Candida Albicans Infection In Immunosuppressed Mice

ObjectiveDeep Candida albicans infection is one of the major causes of death in post-transplant patients and immunosuppressed patients.Establishing a stable and effective animal infection model is significant for studying the mechanism of Candida albicans infection and for testing antifungal drugs in vivo.However,the animal models of deep Candida albicans infection are now produced in various ways,and there is no uniform evaluation method,the infection status is unstable in addition.In this experiment,the effect of different injection methods on model manufacturing was studied by adjusting the injection dosage.Study the appropriate model building method by observing the mouse activity behavior,body weight changes,splenic visceral pathological sections,etcMethodsC57BL/6 male wild mice of 7?8 weeks were selected and given cyclophosphamide 100mg/kg/d(low concentration),150 mg/kg/d(medium concentration),200 mg/kg/d(high concentration)intraperitoneal for 4 days.The changes of activity and body weight of mice were observed.Twenty-four hours after the last injection,the mice were given 1×105/ml conidia Candida albicans solution by tail vein injection or intraperitoneal injection to establish an infection model.Observe the change of activity and survival time.All mice were sacrificed on the 14th day.The spleen was weighed to calculate organ coefficient.Heart,liver,spleen,lung and kidney were taken for H&E staining and PAS stainingResultsAfter intraperitoneal injection of cyclophosphamide in normal mice,mouse in all groups appeared to be quiet,less active,lose weight,significantly reduced diet,and lack of smooth fur,etc.In the high-concentration group,some mice showed unstable standing and slow movements.After intraperitoneal injection of Candida albicans in mice,the mortality rate of mice in the low-concentration group and the medium-concentration group were 17%respectively,the mortality rate in the high concentration group was about 48%,and deaths in the high concentration group all occurred before 8 days.In the tail vein injection group,The death rate of mice in the low concentration group was 66%,the death rate in the medium concentration group was 83%,and the death in the high concentration group was all occurred within 5 days.Tissue fungal culture confirmed that Candida albicans had infected the viscera of the mice,and the body weight of the mice did not increase significantly.Pathological sections showed mycelial growth obviously in some mouse viscera.Among them,there was no obvious fungal infection in the viscera of the low concentration group and the middle concentration group,which was injected Candida albicans intraperitoneally.In the high concentration intraperitoneal injection group,the consequence was a large difference.Some mice had no hyphae,while other mice had obvious fungal hyphae growth.In contrast,mycelial growth can be seen in all tail vein injection group.In the low concentration and middle-concentration groups,lymphocyte infiltration was observed around the mycelium,while the high-concentration group showed obvious fungal mycelial growth without lymphocyte infiltration.In the organs of the above groups,no fungal growth was seen in the spleen,and the mycelium growth in the kidney and heart was the most obvious.Moreover,the spleen of the mice in the low-concentration group showed a relatively sparse germinal zone while the spleen in the high-concentration group had significant atrophy,not obvious germinal zone,infarcts and other lesions partly.Conclusion:Cyclophosphamide can effectively reduce the immunity of mice,and has the most obvious effect on the spleen morphology of mice.Compared with the model of intraperitoneal injection,the method of tail vein injection is smaller differ.In the heart,liver,spleen,lung and kidney vescer,the spleen is least apt to be infected by Candida albicans,and the kidney and heart are more likely to be infected.