颅内接种热灭活隐球菌对小鼠隐球菌脑膜脑炎作用的研究

Effects of Heat-Inactivated Cryptococcus neoformans on an Experimental Murine Model of Meningoencephalitis and on IL-1β,IFN-γand TNF-αExpression on the Brain and Spleen

目的研究脑内接种热灭活的隐球菌(H-CN)在中枢神经系统隐球菌感染中的作用及对小鼠脑和脾白介素-1β(IL-1β)、干扰素γ(IFN-γ)和肿瘤坏死因子α(TNF-α)基因表达的影响。方法建立脑内接种隐球菌造成中枢神经系统感染的小鼠模型,分实验组(给予2次脑内接种H-CN)、对照组(给予2次脑内接种生理盐水),分别取2组小鼠的脑和脾用RT-PCR方法检测IL-1β、IFN-γ及TNF-α的mRNA表达,然后给予2组小鼠脑内接种致死量的隐球菌,观察2组小鼠的生存时间及脑组织中菌落形成单位的变化。结果实验组与对照组相比小鼠生存时间显著延长,小鼠脑组织中隐球菌菌落形成单位明显减少。小鼠脑组织总RNA以IL-1β、IFN-γ、TNF-α引物进行的RT-PCR产物,实验组IL-1β表达阳性,IFN-γ、TNF-α均表达阴性;对照组IL-1β、IFN-γ、TNF-α均表达阴性。小鼠脾组织总RNA以IL-1β、IFN-γ、TNF-α引物进行的RT-PCR产物2组均表达阳性,差异无显著性。结论给予小鼠脑内接种H-CN可提高中枢神经系统对隐球菌感染的抵抗力,中枢神经系统抗隐球菌机制很可能与H-CN引起局部细胞因子IL-1β的分泌有关。

Objective To investigate the effects of heat-inactivated Cryptococcus neoformans(H-CN)on an experimental murine model of meningoencephalitis and on IL-1β,IFN-γand TNF-αgene ex-pression on the brain and spleen.Methods An experimental murine model of intracerebral infection with C.neoformans was established.Mice were divided into H-CN-treated group and control group.The brain and spleen of two groups were collected to obtain total RNA,and IL-1β,IFN-γand TNF-αwere detected by RT-PCR method.After intracerebral challenging with lethal doses of C.neoformans,the survival time and colony forming units(cfu)of C.neoformans in the brain of two group were observed.Results The survival time was prolonged,and cfu of C.neoformans were decreased in the brain of H-CN-treated group in com-parison with those of control group.Expression of IL-1βwas positive,and IFN-γand TNF-αnegative in the brain tissue of H-CN-treated mice;while expression of IL-1β,IFN-γand TNF-αwas all negative in the control mice,as indicated by RT-PCR.Expression of3cytokines,IL-1β,IFN-γand TNF-αwas all positive in the spleen tissue of both groups,suggesting that there was no significant difference in the levels of cytokine gene transcripts in both groups.Conclusion These findings suggest that murine resistance to central nervous system infection of C.neoformans be enhanced by intracerebral administration of H-CN,and anti-cryptococcal mechanism probably involves a local cytokine IL-1βelicitated by H-CN in central nerve system.