Preliminary Study On Evaluation Of Immune Testicular Injury Induced By PD-1 Inhibitor In Rabbits By Two-dimensional Shear Wave Eastography

Objective:The changes of testicular hardness in rabbits treated with PD-1 inhibitor were evaluated by two-dimensional shear wave elastography(2D-SWE),and compared with pathological results,in order to explore the occurrence and development of rabbit immune testicular injury caused by PD-1 inhibitor and the diagnostic value of 2D-SWE technique in immune testicular injury.Methods:Forty-five male New Zealand white rabbits were randomly divided into experimental group(n=25)and control group(n=20).The experimental group received regular infusion of PD-1 inhibitors for four times,while the control group received the same amount of saline for four times at the same time.The changes of testicular parenchyma were observed by conventional two-dimensional ultrasound before infusion(TO stage),14 days after the first infusion(T1 stage),14 days after the second infusion(T2 stage),14 days after the third infusion(T3 stage)and 14 days after the fourth infusion(T4 stage).Young’s modulus of testicular center and subcapsular parenchyma measured by 2D-SWE technique(recorded as Ecenter,Ecapsule).The differences of Young’s modulus in different periods of the same group and different groups in the same period were analyzed.Two rabbits in TO,T1,T2 and T3 stage were killed in the experimental group and one rabbit in the control group,and all the remaining rabbits were sacrificed in T4 stage.The testes were taken for pathological examination,and histological changes were observed.All experimental data were collected and statistically analyzed.Result:1 Survival rate and general condition of two groups of rabbitsThe rabbits in the control group were generally in good condition and had no natural death.In the experimental group,one rabbit died in T2 stage and one rabbit died in T3 stage.Skin Rash and external auditory canal infection were seen in two dead rabbits.2 Ultrasound examination2.1 Two-dimensional conventional ultrasoundThe shape and size of the testis of the two groups of rabbits were normal,the parenchymal echo was homogeneous,and no obvious abnormality was found.In some experimental groups,there was a little effusion in the testis sheath cavity of rabbits,and there was no significant difference between the groups(P>0.05).2.2 SWE imagingIn the experimental group,the Ecenter and Ecapsule gradually increased in TO～T4 stage.The Ecenter and Ecapsule in different periods were compared in pairs,except that there was no significant difference between TO and T1 stage(P>0.05),and the differences between different periods were statistically significant(P<0.05);the Ecapsule was higher than the Ecenter in the same period,and the differences were statistically significant(P<0.05).In the control group,there was no significant change in Ecenter and Ecapsule in T0～T4 stage.Pairwise comparison of Ecenter and Ecapsule between different periods showed no significant difference(P>0.05);Ecapsule was higher than Ecenter in the same period,and the difference was statistically significant(P<0.05).Comparison between the experimental group and the control group:in T0～T1 stage,there was no significant difference between the experimental group and the control group in the same period(P>0.05).In T2～T4 stage,the Ecenter and Ecapsule of the experimental group were higher than these of the control group at the same period,and the differences were statistically significant(P<0.05).3 PathologyControl group:in T0～T4 stage,a little stroma is seen between the seminiferous tubules of the testis under the microscope;Experimental group:in T0～T1 stage,the testicular seminiferous tubule interstitium did not change significantly compared with the control groupin;in T2-T4 stage,interstitial fibroblasts and interstitial cells increased slowly with the prolongation of medication cycle,and more sperm were found in seminiferous tubules in the stage.The blue-stained collagen fibers between seminiferous tubules increased and thickened slightly with time.Conclusion:1.It is feasible to establish an animal model of immune testicular injury by infusion of PD-1 inhibitor.2.With the prolongation of the drug cycle of PD-1 inhibitors,the interstitial components of testicular seminiferous tubules increased,fibrous tissue gradually proliferated,testicular stiffness increased,and immune-related adverse events(irAEs)occurred.3.In evaluating and diagnosing the occurrence,development and severity of immune testicular injury,2D-SWE technology has a high compatibility with pathology,which can provide an effective basis for early clinical diagnosis of immune testicular injury.