Hung Chiung-Yu, Castro-Lopez Natalia, Cole Garry T
Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas, San Antonio, Texas, USA
Department of Biology and South Texas Center for Emerging Infectious Diseases, University of Texas, San Antonio, Texas, USA.
Infect Immun. 2016 Mar 24;84(4):1166-75. doi: 10.1128/IAI.01066-15. Print 2016 Apr.
Coccidioidomycosis is a potentially life-threatening respiratory disease which is endemic to the southwestern United States and arid regions of Central and South America. It is responsible for approximately 150,000 infections annually in the United States alone. Almost every human organ has been reported to harbor parasitic cells of Coccidioides spp. in collective cases of the disseminated form of this mycosis. Current understanding of the mechanisms of protective immunity against lung infection has been largely derived from murine models of pulmonary coccidioidomycosis. However, little is known about the nature of the host response to Coccidioides in extrapulmonary tissue. Primary subcutaneous coccidioidal infection is rare but has been reported to result in disseminated disease. Here, we show that activation of MyD88 and Card9 signal pathways are required for resistance to Coccidioides infection following subcutaneous challenge of C57BL/6 mice, which correlates with earlier findings of the protective response to pulmonary infection. MyD88(-/-) andCard9(-/-) mice recruited reduced numbers of T cells, B cells, and neutrophils to the Coccidioides-infected hypodermis com pared to wild-type mice; however, neutrophils were dispensable for resistance to skin infection. Further studies have shown that gamma interferon (IFN-γ) production and activation of Th1 cells characterize resistance to subcutaneous infection. Furthermore, activation of a phagosomal enzyme, inducible nitric oxide synthase, which is necessary for NO production, is a requisite for fungal clearance in the hypodermis. Collectively, our data demonstrate that MyD88- and Card9-mediated IFN-γ and nitric oxide production is essential for protection against subcutaneous Coccidioides infection.
球孢子菌病是一种可能危及生命的呼吸道疾病,在美国西南部以及中美洲和南美洲的干旱地区流行。仅在美国,每年就有大约15万例感染病例。据报道,在这种真菌病的播散型病例中,几乎每个人体器官都有球孢子菌属的寄生细胞。目前对肺部感染保护性免疫机制的了解主要来自肺球孢子菌病的小鼠模型。然而,对于肺外组织中宿主对球孢子菌的反应性质知之甚少。原发性皮下球孢子菌感染很少见,但据报道会导致播散性疾病。在这里,我们表明,C57BL/6小鼠皮下感染球孢子菌后,抵抗感染需要MyD88和Card9信号通路的激活,这与先前对肺部感染保护性反应的研究结果相关。与野生型小鼠相比,MyD88(-/-)和Card9(-/-)小鼠募集到被球孢子菌感染的皮下组织中的T细胞、B细胞和中性粒细胞数量减少;然而,中性粒细胞对于抵抗皮肤感染并非必需。进一步的研究表明,γ干扰素(IFN-γ)的产生和Th1细胞的激活是抵抗皮下感染的特征。此外,吞噬体酶诱导型一氧化氮合酶的激活是皮下组织中真菌清除的必要条件,而诱导型一氧化氮合酶的激活是产生NO所必需的。总的来说,我们的数据表明,MyD88和Card9介导的IFN-γ和一氧化氮的产生对于预防皮下球孢子菌感染至关重要。