山苍子油对小鼠系统性白念珠菌感染的影响

目的研究山苍子油对小鼠系统性白念珠菌感染的治疗作用。方法建立小鼠系统性白念珠菌感染模型,观察给药后小鼠中位生存时间,并检测给药后小鼠肾脏菌落形成单位计数。结果山苍子油能明显延长小鼠的中位生存时间,降低肾脏菌落形成单位计数。结论山苍子油对小鼠系统性白念珠菌感染具有治疗作用,值得进一步研究和开发。     

新生隐球菌感染小鼠肺泡巨噬细胞相关细胞因子与疾病病程相关性研究

目的通过检测新生隐球菌感染小鼠巨噬细胞相关细胞因子的表达水平,探讨其在感染小鼠疾病病程的作用。方法应用单侧小鼠鼻孔接种感染新生隐球菌建立小鼠吸入感染隐球菌模型,在感染后第1、4、7、11、14、18、21天,PAS染色观察小鼠肺组织病理变化,并通过RT-PCR检测相应时间点小鼠巨噬细胞内相关细胞因子(IL-6、IL-8、TGF-β、TNF-α)的表达。结果小鼠吸入感染隐球菌后,PAS染色发现第4天肺内散在分布隐球菌,第7天可见肉芽肿形成,第11天大量炎性细胞浸润,第14天见肉芽肿内大量隐球菌,第18天隐球菌分布至全肺,第21天肺组织大量坏死;RT-PCR结果显示TGF-β和IL-6的表达在感染后14天达到最高值,然后逐渐降低,其中TGF-β升高幅度更为明显。结论在新生隐球菌感染小鼠中,TGF-β参与了机体的抗真菌免疫,在调节炎症反应方面有重要作用。     

舍曲林抗新生隐球菌的体外及动物实验研究

目的评估舍曲林抗新生隐球菌的效果。方法实验分为6组,分别为空白对照组、10 mg/mL氟康唑、10 mg/mL舍曲林、20 mg/mL舍曲林、10 mg/mL氟康唑联用10 mg/mL舍曲林以及10 mg/mL氟康唑联用20 mg/mL舍曲林组。通过体外药敏试验及BALBc小鼠新生隐球菌动物探讨各组间抗隐球菌效果的差异。结果体外药敏试验发现舍曲林可有效降低新生隐球菌菌落数,当与氟康唑联用时抑菌效果更显著。动物实验发现2种浓度的舍曲林都可明显降低感染小鼠实验早期脑、肺组织的新生隐球菌菌落数,但在实验后期,低浓度的舍曲林对感染小鼠脑组织失去抑菌作用。脑、肺组织中,舍曲林治疗对新生隐球菌的抗菌效果均不如氟康唑。舍曲林与氟康唑联合用药对新生隐球菌模型小鼠肺组织的抗菌效果强于单用舍曲林或氟康唑。结论舍曲林具有抗新生隐球菌的作用,当与氟康唑联合用药时可起到协同作用。     

新生隐球菌共孵育后小鼠脑血管内皮细胞S100A10基因的表达水平变化

目的探讨S100A10基因在新生隐球菌感染脑血管内皮细胞中的作用。方法将新生隐球菌H99株与小鼠脑血管内皮细胞共孵育后,不同时间终止共孵育,提取小鼠脑血管内皮细胞的总RNA,采用实时定量荧光PCR检测S100A10的表达水平。结果在与新生隐球菌共孵育2h后,小鼠脑血管内皮细胞中的S100A10基因表达水平随着共孵育时间的延长而升高（P〈0.05）。结论S100A10基因在新生隐球菌对中枢神经系统的易感性存在一定的作用。     

新生隐球菌毒性因子研究进展

新生隐球菌为环境中的真菌,是引起免疫损伤患者脑膜脑炎的主要病原体。新生隐球菌有毒株能够快速适应宿主环境的诸多变化,改变基因/蛋白的表达,利用多种策略在宿主防御和治疗药物的压力下可塑性地适应和生存,并在宿主不同的组织器官中顽强生存,某些免疫系统完好的宿主也不能幸免。新生隐球菌应用伪装躲避识别、逃避固有免疫和适应性免疫应答、改变细胞内转运等手段使病原体穿越天然屏障在脑中生长/持续感染。了解其中的毒性因子在持续感染中的作用,有助于揭示新生隐球菌的致病机理。     

新生隐球菌感染流行病学现状及耐药机制相关研究进展

新生隐球菌是一种广泛存在于环境中的酵母类真菌,主要侵犯中枢神经系统引起隐球菌性脑膜炎。HIV感染是导致隐球菌感染的主要危险因素之一,但近年来关于非HIV患者隐球菌感染的报道不断增加。体外药敏试验证实大部分新生隐球菌对棘白菌素类药物具有内在抗性。两性霉素B和氟康唑是用于隐球菌感染治疗的一线药物,而长期广泛用药引起新生隐球菌对氟康唑的耐药率逐年升高,患者临床治疗失败率居高不下。为进一步加深对新生隐球菌的认识,本文结合国内外流行病学报道及相关研究,从感染现状、生物学特征、诊治方法和耐药性等方面进行综述,以期为新生隐球菌性脑膜炎的临床诊治提供参考。     

非霍奇金淋巴瘤伴播散性隐球菌感染1例

患者男,16岁,非霍奇金淋巴瘤化疗5个月,发热1周,血培养新生隐球菌生长。脑脊液真菌镜检可见少量孢子,真菌培养阴性。血清及脑脊液隐球菌荚膜多糖抗原乳胶凝集试验及胶体金试验阳性。头颅核磁平扫未见明显异常,胸部增强CT可见左肺下叶后基底段结节,感染可能性大。分离菌株ITS及NL区测序比对菌种鉴定为新生隐球菌新生变种。确诊播散性隐球菌病。予两性霉素B及氟胞嘧啶强化治疗4周,后由于副作用严重,予氟康唑巩固及维持治疗1年获得痊愈,随访4年多无复发。     

隐球菌感染的免疫疗法

隐球菌属属于担子菌门一冬孢菌纲一黑粉菌目一黑粉菌科,包括37个不同种[1],其中能对人类致病的主要是新生隐球菌和格特隐球菌,而其他变种如罗伦隐球菌、浅白隐球菌等几乎不感染人类[2]。新生隐球菌感染好发于免疫低下的人群,包括HIV感染、接受实体器官移植以及接受其他免疫抑制剂治疗的人群。与新生隐球菌相反的是,格特隐球菌多发生在免疫正常的人群[3]。     

新生隐球菌生物膜动物感染模型的构建及其活性的检测

目的 构建一种简便易行的新生隐球菌生物膜感染动物模型.方法 采用大鼠皮下置管法构建新生隐球菌生物膜感染动物模型,并使用电子扫描显微镜观察新生隐球菌体内形成生物膜的结构;采用MTT法对获得的体内生物膜结构进行活性的检测.结果 成功构建了新生隐球菌生物膜大鼠感染模型;MTT法检测体内生物膜活性表明,随着体内培养时间的延长,生物膜活性增强,与直接镜检和电镜观察结果一致.结论 新生隐球菌生物膜大鼠模型简单易行,便于操作,对于研究新生隐球菌生物膜体内活性的研究具有一定的实际应用价值.     

新生隐球菌半胱氨酸转运蛋白Mup1鉴定及其表达调控研究

【目的】鉴定新生隐球菌(Cryptococcus neoformans)的半胱氨酸转运蛋白及其对致病性的影响。【方法】构建候选基因敲除株,检测突变株以半胱氨酸为唯一硫源的生长情况;检测半胱氨酸转运蛋白Mup1对新生隐球菌毒力因子表达和不同胁迫条件下生长的影响;通过新生隐球菌大蜡螟(Galleria mellonella)和小鼠感染模型分析Mup1对致病性的影响;通过转录组分析和酵母单杂交研究硫代谢核心转录因子Cys3与Mup1的调控关系。【结果】Mup1具有转运半胱氨酸、胱氨酸、胱硫醚和同型半胱氨酸的能力。基因MUP1缺失不影响毒力因子表达和细胞对应激的反应。大蜡螟和小鼠隐球菌感染模型表明Mup1对新生隐球菌的致病性无显著影响。转录组分析和酵母单杂交实验显示Cys3可能间接调控MUP1的转录。【结论】新生隐球菌Mup1具有转运半胱氨酸、胱氨酸、胱硫醚和同型半胱氨酸的功能,但不影响致病性,基因转录可能受Cys3的间接调控。     

Contribution of interferon-γ in protecting mice during pulmonary and disseminated infection with Cryptococcus neoformans

Abstract In the present study, the role of interferon-γ (IFN-γ) in the host resistance against Cryptococcus neoformans was examined using a murine model of pulmonary and disseminated infection. In this model, mice were infected intratracheally with live yeast cells, and the histological changes in the lungs and the number of microorganisms in the lung and brain were compared in mice treated and untreated with anti-IFN-γ monoclonal antibody (mAb) to define the contribution of endogenously synthesized IFN-γ in the natural course of infection. Administration of this mAb reduced the accumulation of inflammatory cells in the alveolar septa, peribronchial and perivascular areas, and promoted the expansive growth of microorganisms in the alveoli and destruction of alveolar structure. The neutralization of endogenous IFN-γ by mAb increased the number of microorganisms in the lung and brain, and significantly shortened the survival time of infected mice. On the other hand, administration of IFN-γ decreased the number of microorganisms in these organs, and significantly extended their survival time. Considered together, our results suggest that endogenous IFN-γ protects mice from infection with C. neoformans by inducing a cellular inflammatory response, potentiating the clearance of microorganism from the lungs and preventing its dissemination into the central nervous system.     

Contributions of the MyD88-dependent receptors IL-18R, IL-1R, and TLR9 to host defenses following pulmonary challenge with Cryptococcus neoformans

Signaling via the adapter protein, MyD88, is important in the host defense against Cryptococcus neoformans infection. While certain Toll-like receptors (TLRs) can enhance the clearance of Cryptococcus, the contributions of MyD88-dependent, TLR-independent pathways have not been fully investigated. We examined the roles of IL-1R and IL-18R in vivo by challenging C57BL/6 mice with a lethal strain of Cryptococcus. We found that the absence of IL-18R, but not IL-1R, causes a shift in the survival curve following pulmonary delivery of a virulent strain of C. neoformans (H99). Specifically, IL-18R-deficient mice have significantly shorter median survival times compared to wild-type mice following infection. Cytokine analysis of lung homogenates revealed that deficiency of IL-IR, IL-18R, or MyD88 is associated with diminished lung levels of IL-1β. In order to compare these findings with those related to TLR-deficiency, we studied the effects of TLR9-deficiency and found that deficiency of TLR9 also affects the survival curve of mice following challenge with C. neoformans. Yet the lungs from infected TLR9-deficient mice have robust levels of IL-1β. In summary, we found that multiple signaling components can contribute the MyD88-dependent host responses to cryptococcal infection in vivo and each drives distinct pulmonary responses.     

Contribution of complement component C5 to the pathogenesis of experimental murine cryptococcosis

C5-deficient (C5-) mice succumb much sooner after intravenous inoculation with Cryptococcus neoformans than do C5-sufficient (C5+) mice. The C5- mice developed acute, fatal cryptococcal pneumonia, whereas the C5+ mice did not. The pneumonia was characterized by lung viable counts in C5- mice up to 1000-fold higher than in C5+, initial sequestration of twice as much 59Fe-labeled C. neoformans, and subsequent development of pulmonary edema. Chemotaxis of heterophils (PMNs) and mononuclear cells in response to C. neoformans was markedly greater in C5+ mice than in C5- animals. The effect of C5 on localization and growth of C. neoformans in the lung appeared to account for the disparate survival times of C5+ and C5+ mice after intravenous inoculation with C. neoformans.     

Depletion of CD4+ (L3T4+) lymphocytes in vivo impairs murine host defense to Cryptococcus neoformans

T cell-mediated immunity has been shown to play an important role in the host defense to Cryptococcus neoformans. Infections due to C. neoformans are increased in patients with AIDS who are deficient in the CD4+ subset of T lymphocytes. Thus, the effect of CD4+ (L3T4+) lymphocyte depletion on murine host defenses to C. neoformans was studied. The mAb GK 1.5 was administered to mice, and CD4+ T lymphocyte depletion was confirmed by the analysis of T cell subsets in blood, spleen, lymph node, and lung. Evidence of a functional defect was confirmed by demonstrating that the splenocytes of treated mice were unable to proliferate in response to class II incompatible spleen cells. Furthermore, delayed type hypersensitivity to C. neoformans was abrogated by CD4+ lymphocyte depletion. Mice depleted of CD4+ lymphocytes were inoculated with a virulent strain of C. neoformans by the i.v. or the intratracheal route. After i.v. inoculation of C. neoformans, the survival of mice depleted of CD4+ lymphocytes was reduced (27.8 +/- 1.8 vs 36.0 +/- 3.1 days, p less than 0.04). After intratracheal inoculation, C. neoformans disseminated from the lung to extrapulmonary organs. Dissemination occurred earlier in mice depleted of CD4+ lymphocytes compared to mice that received control antibody, and the burden of C. neoformans in extrapulmonary organs was greater in mice depleted of CD4+ lymphocytes than control mice. Surprisingly, there was no increase in the burden of C. neoformans in the lungs of CD4+ lymphocyte-depleted mice. Survival of mice inoculated with C. neoformans and depleted of CD4+ lymphocytes was reduced compared to control mice and was related to the increased rate of accumulation of organisms in the brains of treated mice. The mean survival of GK 1.5-treated mice was 34.1 +/- 0.9 days compared to control mice with a mean survival of 40.6 +/- 9 days (p less than 0.001). These data suggest that CD4+ lymphocytes play a prominent role in the host defense of infections due to C. neoformans, that CD4+ lymphocytes are required in extrapulmonary organs for optimal clearance of C. neoformans and that CD4+ lymphocytes are critical for survival of mice infected with C. neoformans.     

Protection from direct cerebral cryptococcus infection by interferon-gamma-dependent activation of microglial cells

The brain represents a significant barrier for protective immune responses in both infectious disease and cancer. We have recently demonstrated that immunotherapy with anti-CD40 and IL-2 can protect mice against disseminated Cryptococcus infection. We now applied this immunotherapy using a direct cerebral cryptococcosis model to study direct effects in the brain. Administration of anti-CD40 and IL-2 significantly prolonged the survival time of mice infected intracerebrally with Cryptococcus neoformans. The protection was correlated with activation of microglial cells indicated by the up-regulation of MHC II expression on brain CD45(low)CD11b(+) cells. CD4(+) T cells were not required for either the microglial cell activation or anticryptococcal efficacy induced by this immunotherapy. Experiments with IFN-gamma knockout mice and IFN-gammaR knockout mice demonstrated that IFN-gamma was critical for both microglial cell activation and the anticryptococcal efficacy induced by anti-CD40/IL-2. Interestingly, while peripheral IFN-gamma production and microglial cell activation were observed early after treatment, negligible IFN-gamma was detected locally in the brain. These studies indicate that immunotherapy using anti-CD40 and IL-2 can augment host immunity directly in the brain against C. neoformans infection and that IFN-gamma is essential for this effect.     

Th1-Th2 cytokine kinetics in the bronchoalveolar lavage fluid of mice infected with Cryptococcus neoformans of different virulences

Th1 immune response plays an important role in protection against infection with Cryptococcus neoformans in mice. We investigated the effect of virulence of C. neoformans on cytokine production in the lung of a mouse model of pulmonary cryptococcosis. BALB/c mice were inoculated intratracheally with a high or low virulence strain of C. neoformans, followed by serial measurements of Th1 and Th2 cytokine concentrations in the bronchoalveolar lavage (BAL) fluid using appropriate enzyme-linked immunosorbent assay kits. The number of colony-forming units (CFU) increased with time, and all mice infected with the highly virulent strain were dead at 28 days after inoculation. In contrast, the number of microorganisms diminished with time in the mice infected with the low virulence strain during the 4-week study. The numbers of neutrophils and lymphocytes in the BAL fluid paralleled those of CFU. High neutrophil counts were observed in the BAL fluid of mice infected with the highly virulent strain, while lymphocyte counts were increased only in the later part of the study in mice infected with the high and low virulence strains. The concentrations of Th2 cytokine, interleukin (IL)-4 were significantly higher in mice infected with the highly virulent strain at days 14 and 21 of infection, whereas the level of Th1 cytokine, interferon-gamma, was significantly higher in the latter strain at days 7 and 14. Our results suggest that strain-specific difference in the organism's ability to induce (or evade) the host immune system contributes to the outcome of infection.     

Antibody efficacy in murine pulmonary Cryptococcus neoformans infection: a role for nitric oxide

We investigated the pathogenesis of pulmonary Cryptococcus neoformans infection and passive Ab efficacy in mice deficient in inducible NO synthase (NOS2(-/-)) and the parental strain. Parental mice lived significantly longer than NOS2(-/-) mice after intratracheal infection, despite having a higher lung fungal burden. Administration of Ab reduced lung CFU in both NOS2(-/-) and parental mice, but prolonged survival and increased the inflammatory response only in parental mice. Ab administration was associated with increased serum nitrite and reduced polysaccharide levels in parental mice. Eosinophils were present in greater numbers in the lung of infected NOS2(-/-) mice than parental mice, irrespective of Ab administration. C. neoformans infection in NOS2(-/-) mice resulted in significantly higher levels of IFN-gamma, monocyte chemoattractant protein-1, and macrophage-inflammatory protein-1alpha than parental mice. Ab administration had different effects on infected NOS2(-/-) and parental mice with respect to IFN-gamma, monocoyte chemoattractant protein-1, and macrophage-inflammatory protein-1alpha levels. Ab administration increased lung levels of IFN-gamma in parental mice and reduced levels in NOS2(-/-) mice. The results indicate that NO is involved in the regulation of cytokine expression in response to cryptococcal pneumonia and is necessary for Ab efficacy against C. neoformans in mice. Our findings indicate a complex relationship between Ab efficacy against C. neoformans and cytokine expression, underscoring the interdependency of cellular and humoral defense mechanisms.     

Interleukin-4 weakens host resistance to pulmonary and disseminated cryptococcal infection caused by combined treatment with interferon-gamma-inducing cytokines.

We examined the role of interleukin (IL)-4 in host resistance against infection with Cryptococcus neoformans. First, we examined the effects of a neutralizing anti-IL-4 monoclonal antibody (mAb) on survival of mice infected intratracheally with this fungal pathogen. We also compared the number of live C. neoformans in lungs and brains of treated and untreated mice. Treatment with anti-IL-4 mAb significantly prolonged survival of infected mice and reduced the lung and brain burdens of C. neoformans, which was associated with increased production of IFN-gamma in lungs. In the next experiments, infected mice were treated with two IFN-gamma-inducing cytokines, IL-12 and IL-18, known to enhance protection against infection. We then evaluated the effect of such treatment on the number of live microorganisms and concentration of IL-4 in lungs. These two parameters showed a statistically significant relationship, suggesting a negative regulation of host protection by IL-4. Finally, we examined the effects of IL-4 treatment and administration of neutralizing anti-IL-4 mAbs on host protection against C. neoformans and local production of IFN-gamma in lungs induced by treatment with IL-12/IL-18. The former treatment suppressed host protection and reduced IFN-gamma production, while the latter produced the opposite effects. Our results indicated that IL-4 suppressed the host defense mechanisms against infection with C. neoformans potentiated by IFN-gamma-inducing cytokines probably through the suppression of local production of IFN-gamma.