不同日龄乳鼠感染EV71毒株后组织免疫学特征实验研究OA

Objective To investigate the histopathological manifestations,immune cell distribution and cytokine expression pro-files in suckling mice of different ages following Enterovirus 71(EV71)infection.Methods Suckling mice aged 7,14,18,and 21 days were selected to establish infection models by intraperitoneal injection with EV71 strain GD10-12.Survival rate,body weight changes,and clinical scores of the mice were dynamically monitored.Histological examination was performed to evaluate the structural maturity of immune organs such as bone marrow and thymus.Flow cytometry was used to detect the proportions and numbers of type 3 innate lymphoid cells(ILC3s),CD4+T cells,CD8+T cells,and other immune cell subsets in the small in-testine before and after infection.Quantitative real-time polymerase chain reaction(RT-qPCR)was employed to determine the relative expression levels of interleukin-1β(IL-1β),interleukin-22(IL-22),interleukin-23(IL-23)and tumor necrosis factor-α(TNF-α)before and after infection.Results After EV71 infection,mortality rates of suckling mice significantly decreased with increasing age(χ2=29.15,P<0.001):all 7-day-old mice died within 3 days,all 14-day-old mice died within 4 days,all 18-day-old mice died within 7 days,whereas no 21-day-old mice died.Body weight was arrested or declined before death in 7～18-day-old mice,while 21-day-old mice maintained normal weight gain(F=73.82,P<0.001).Clinical score in 7～18-day-old mice rapidly increased to 3～5 points and remained at severe levels for 2～3 days,whereas 21-day-old mice only reached scores of 1-2 and re-covered to 0 by day 8 post-infection(F=4.633,P=0.017).Histological results revealed progressive maturation of immune organs with age,with 18-21-day-old mice displaying features close to those of adult mice.Immune cell profiling showed that the differ-ences in the proportion of various immune cells in the small intestine of 7～21-day-old mice gradually expanded,except for NK cells:compared with younger suckling mice,the proportions of CD4+T cells,CD8+T cells,and γδT cells were significantly in-creased,while the proportions of B cells and dendritic cells were significantly decreased(F=38.861～847.276,all P<0.001).Com-pared with pre-infection evels within the same age group,ILC3 levels significantly decreased after infection in 7～18-day-old mice(t=5.828,5.854,and 4.611,respectively;all P<0.05),but significantly increased in 21-day-old mice(t=-4.032,P=0.016).Cytokine detection showed that pre-infection expression of IL-1β and TNF-α gradually decreased with age(F=264.322,104.483,both P<0.05),whereas IL-22 and IL-23 gradually increased(F=176.101,180.815,both P<0.05).After infection,IL-1β levels in 7～21-day-old mice(t=-136.593 to-12.890)and TNF-α levels in 14～21-day-old mice(t=-38.505～-25.589)were significantly increased(all P<0.001),while IL-22 levels in 14～21-day-old mice(t=8.778～36.316)and IL-23 levels in 7～21-day-old mice(t=5.362～74.642)were significantly decreased(all P<0.001).Conclusions Significant age-dependent differences in tis-sue immunological characteristics are observed in EV71-infected suckling mice.Resistance to EV71 infection increases with age,a process closely associated with immune organ maturation,dynamic regulation of ILC3s,and cytokine network balance.