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溶血性贫血和疟原虫特异性因素均可增加小鼠对非伤寒沙门氏菌血清型鼠伤寒感染的易感性。

Both hemolytic anemia and malaria parasite-specific factors increase susceptibility to Nontyphoidal Salmonella enterica serovar typhimurium infection in mice.

机构信息

Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California 95616, USA.

出版信息

Infect Immun. 2010 Apr;78(4):1520-7. doi: 10.1128/IAI.00887-09. Epub 2010 Jan 25.

Abstract

Severe pediatric malaria is an important risk factor for developing disseminated infections with nontyphoidal Salmonella serotypes (NTS). While recent animal studies on this subject are lacking, early work suggests that an increased risk for developing systemic NTS infection during malaria is caused by hemolytic anemia, which leads to reduced macrophage microbicidal activity. Here we established a model for oral Salmonella enterica serotype Typhimurium challenge in mice infected with Plasmodium yoelii nigeriensis. Initial characterization of this model showed that 5 days after coinoculation, P. yoelii nigeriensis infection increased the recovery of S. Typhimurium from liver and spleen by approximately 1,000-fold. The increased bacterial burden could be only partially recapitulated by antibody-mediated hemolysis, which increased the recovery of S. Typhimurium from liver and spleen by 10-fold. These data suggested that both hemolysis and P. yoelii nigeriensis-specific factors contributed to the increased susceptibility to S. Typhimurium. The mechanism by which hemolysis impaired resistance to S. Typhimurium was further investigated. In vitro, S. Typhimurium was recovered 24 h after infection of hemophagocytic macrophages in 2-fold-higher numbers than after infection of mock-treated macrophages, making it unlikely that reduced macrophage microbicidal activity was solely responsible for hemolysis-induced immunosuppression during malaria. Infection with P. yoelii nigeriensis, but not antibody-mediated hemolysis, reduced serum levels of interleukin-12p70 (IL-12p70) in response to S. Typhimurium challenge. Collectively, studies establishing a mouse model for this coinfection suggest that multiple distinct malaria-induced immune defects contribute to increased susceptibility to S. Typhimurium.

摘要

严重的小儿疟疾是导致非伤寒沙门氏菌血清型(NTS)全身感染的一个重要危险因素。虽然目前缺乏这方面的动物研究,但早期研究表明,疟疾导致的溶血性贫血会增加全身 NTS 感染的风险,从而降低巨噬细胞的杀菌活性。在此,我们建立了一种在感染恶性疟原虫的小鼠中口服感染鼠伤寒沙门氏菌血清型 Typhimurium 的模型。该模型的初步特征表明,在共接种后 5 天,感染恶性疟原虫会使鼠伤寒沙门氏菌从肝脏和脾脏中的回收量增加约 1000 倍。抗体介导的溶血性贫血只能部分重现这种细菌负荷的增加,使鼠伤寒沙门氏菌从肝脏和脾脏中的回收量增加 10 倍。这些数据表明,溶血性贫血和恶性疟原虫特异性因素都导致了对鼠伤寒沙门氏菌的易感性增加。进一步研究了溶血性贫血削弱对鼠伤寒沙门氏菌抵抗力的机制。在体外,感染吞噬性巨噬细胞 24 小时后,感染鼠伤寒沙门氏菌的巨噬细胞比感染模拟处理的巨噬细胞回收的鼠伤寒沙门氏菌数量多 2 倍,这表明减少巨噬细胞的杀菌活性不太可能是溶血性贫血引起疟疾期间免疫抑制的唯一原因。感染恶性疟原虫而非抗体介导的溶血性贫血会降低血清中白细胞介素-12p70(IL-12p70)的水平,以响应鼠伤寒沙门氏菌的挑战。总之,建立这种混合感染的小鼠模型的研究表明,多种不同的疟疾引起的免疫缺陷导致对鼠伤寒沙门氏菌的易感性增加。

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