肠炎沙门氏菌血清型鼠伤寒糖蛋白水解酶调节肠道聚糖并促进小肠侵袭。
Salmonella enterica serovar Typhimurium chitinases modulate the intestinal glycome and promote small intestinal invasion.
机构信息
Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, United States of America.
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, United States of America.
出版信息
PLoS Pathog. 2022 Apr 28;18(4):e1010167. doi: 10.1371/journal.ppat.1010167. eCollection 2022 Apr.
Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the leading causes of food-borne illnesses worldwide. To colonize the gastrointestinal tract, S. Typhimurium produces multiple virulence factors that facilitate cellular invasion. Chitinases have been recently emerging as virulence factors for various pathogenic bacterial species, and the S. Typhimurium genome contains two annotated chitinases: STM0018 (chiA) and STM0233. However, the role of these chitinases during S. Typhimurium pathogenesis is unknown. The putative chitinase STM0233 has not been studied previously, and only limited data exists on ChiA. Chitinases typically hydrolyze chitin polymers, which are absent in vertebrates. However, chiA expression was detected in infection models and purified ChiA cleaved carbohydrate subunits present on mammalian surface glycoproteins, indicating a role during pathogenesis. Here, we demonstrate that expression of chiA and STM0233 is upregulated in the mouse gut and that both chitinases facilitate epithelial cell adhesion and invasion. S. Typhimurium lacking both chitinases showed a 70% reduction in invasion of small intestinal epithelial cells in vitro. In a gastroenteritis mouse model, chitinase-deficient S. Typhimurium strains were also significantly attenuated in the invasion of small intestinal tissue. This reduced invasion resulted in significantly delayed S. Typhimurium dissemination to the spleen and the liver, but chitinases were not required for systemic survival. The invasion defect of the chitinase-deficient strain was rescued by the presence of wild-type S. Typhimurium, suggesting that chitinases are secreted. By analyzing N-linked glycans of small intestinal cells, we identified specific N-acetylglucosamine-containing glycans as potential extracellular targets of S. Typhimurium chitinases. This analysis also revealed a differential abundance of Lewis X/A-containing glycans that is likely a result of host cell modulation due to the detection of S. Typhimurium chitinases. Similar glycomic changes elicited by chitinase deficient strains indicate functional redundancy of the chitinases. Overall, our results demonstrate that S. Typhimurium chitinases contribute to intestinal adhesion and invasion through modulation of the host glycome.
鼠伤寒沙门氏菌(Salmonella enterica serovar Typhimurium,S. Typhimurium)是全球食源性疾病的主要原因之一。为了在胃肠道中定植,S. Typhimurium 产生了多种促进细胞侵袭的毒力因子。几丁质酶最近作为各种致病性细菌物种的毒力因子而出现,而 S. Typhimurium 基因组包含两个注释的几丁质酶:STM0018(chiA)和 STM0233。然而,这些几丁质酶在 S. Typhimurium 发病机制中的作用尚不清楚。假定的几丁质酶 STM0233 以前尚未被研究过,而 ChiA 只有有限的数据。几丁质酶通常水解几丁质聚合物,而几丁质聚合物在脊椎动物中不存在。然而,在感染模型中检测到 chiA 的表达,并且纯化的 ChiA 切割存在于哺乳动物表面糖蛋白上的碳水化合物亚基,表明其在发病机制中起作用。在这里,我们证明了 chiA 和 STM0233 的表达在小鼠肠道中上调,并且这两种几丁质酶均促进上皮细胞粘附和侵袭。体外缺失这两种几丁质酶的鼠伤寒沙门氏菌对小肠上皮细胞的侵袭减少了 70%。在胃肠炎小鼠模型中,几丁质酶缺陷型 S. Typhimurium 菌株在小肠组织的侵袭中也明显减弱。这种侵袭减少导致 S. Typhimurium 向脾脏和肝脏的传播明显延迟,但几丁质酶不是系统生存所必需的。野生型 S. Typhimurium 的存在挽救了几丁质酶缺陷型菌株的侵袭缺陷,这表明几丁质酶是分泌的。通过分析小肠细胞的 N-连接糖,我们鉴定了特定的 N-乙酰葡萄糖胺含有聚糖作为 S. Typhimurium 几丁质酶的潜在细胞外靶标。这种分析还揭示了 Lewis X/A 含有聚糖的差异丰度,这可能是由于宿主细胞对 S. Typhimurium 几丁质酶的检测而发生的调制的结果。几丁质酶缺陷型菌株引起的类似糖组变化表明几丁质酶具有功能冗余性。总的来说,我们的结果表明,S. Typhimurium 几丁质酶通过调节宿主糖组促进肠道粘附和侵袭。