Department of Oral Health and Diagnostic Sciences, UConn Health, Farmington, Connecticut, USA.
Department of Computer Science and Engineering, University of Connecticutgrid.63054.34grid.208078.5grid.63054.34, Storrs, Connecticut, USA.
mBio. 2021 Aug 31;12(4):e0193721. doi: 10.1128/mBio.01937-21. Epub 2021 Aug 17.
Oropharyngeal candidiasis (OPC) is the most prevalent oral infection in immunocompromised patients, primarily associated with Candida albicans. Increasing evidence points to a significant role of mucosal bacteria on the transition of C. albicans from commensal to pathogenic. In this work, we hypothesized that changes in the abundance or composition of the mucosal bacterial microbiota induced by dietary sucrose during the development of OPC can modulate C. albicans virulence. C. albicans burdens and mucosal lesions were evaluated in a mouse cortisone immunosuppression model amended with sucrose. We also analyzed the mucosal bacterial composition using 16S rRNA gene sequencing and culture methods. In immunocompetent mice, sucrose significantly increased total bacterial burdens and reduced alpha diversity, by increasing the relative abundance of mitis group streptococci. In immunocompromised mice, C. albicans infection was associated with a significantly reduced bacterial alpha diversity due to an increase in the relative abundance of enterococci. When exposed to dietary sucrose, these mice had reduced C. albicans burdens and reduced bacterial alpha diversity, associated with an increase in the relative abundance of . SparCC correlation networks showed a significant negative correlation between and in all -infected mice. Depletion of lactobacilli with antibiotic treatment partially restored C. albicans burdens in mice receiving sucrose. In coculture experiments, mouse oral Lactobacillus johnsonii isolates inhibited growth of Enterococcus faecalis isolates and C. albicans. These results support the hypothesis that the sucrose-induced attenuation of C. albicans virulence was a result of changes in the mucosal bacterial microbiome characterized by a reduction in enterococci and an increase in lactobacilli. By comparing Candida albicans virulence and the mucosal bacterial composition in a mouse oral infection model, we were able to dissect the effects of the host environment (immunosuppression), infection with C. albicans, and local modulating factors (availability of sucrose as a carbon source) on the mucosal bacterial microbiome and its role on fungal virulence. We showed that changes in endogenous microbial communities in response to sucrose can lead to attenuation of fungal disease. We also showed that Lactobacillus johnsonii may curtail virulence both by inhibiting its growth and by inhibiting the growth of potentially synergistic bacteria such as enterococci. Our results support the concept that pathogenesis should be viewed in the contexts of both a susceptible host and a mucosal bacterial microbiota conducive to virulence.
口腔白色念珠菌病(OPC)是免疫功能低下患者最常见的口腔感染,主要与白色念珠菌有关。越来越多的证据表明,黏膜细菌在白色念珠菌从共生菌向致病菌的转变中起着重要作用。在这项工作中,我们假设在 OPC 发展过程中,饮食蔗糖引起的黏膜细菌微生物群的丰度或组成的变化可以调节白色念珠菌的毒力。在加入蔗糖的皮质甾酮免疫抑制小鼠模型中评估白色念珠菌负荷和黏膜损伤。我们还使用 16S rRNA 基因测序和培养方法分析了黏膜细菌组成。在免疫功能正常的小鼠中,蔗糖显著增加了总细菌负荷,通过增加米氏链球菌的相对丰度降低了 alpha 多样性。在免疫功能低下的小鼠中,由于肠球菌相对丰度的增加,白色念珠菌感染与细菌 alpha 多样性的显著降低有关。当暴露于饮食蔗糖时,这些小鼠的白色念珠菌负荷降低,细菌 alpha 多样性降低,与乳杆菌相对丰度的增加有关。 SparCC 相关网络分析显示,所有感染小鼠中 与 之间存在显著的负相关。抗生素处理消耗乳杆菌可部分恢复接受蔗糖的小鼠中的白色念珠菌负荷。在共培养实验中,小鼠口腔乳杆菌分离株抑制粪肠球菌分离株和白色念珠菌的生长。这些结果支持这样的假设,即蔗糖诱导的白色念珠菌毒力减弱是由黏膜细菌微生物组的变化引起的,其特征是肠球菌减少和乳杆菌增加。通过比较小鼠口腔感染模型中白色念珠菌的毒力和黏膜细菌组成,我们能够剖析宿主环境(免疫抑制)、白色念珠菌感染和局部调节因素(蔗糖作为碳源的可用性)对黏膜细菌微生物组及其对真菌毒力的影响。我们表明,对蔗糖的内源性微生物群落的变化可导致真菌病的减弱。我们还表明,约翰逊乳杆菌通过抑制其生长和抑制潜在协同细菌(如肠球菌)的生长来抑制 毒力。我们的研究结果支持这样的概念,即应根据易感宿主和有利于毒力的黏膜细菌微生物群来观察 发病机制。