Protease Activity of Campylobacter jejuni HtrA Modulates Distinct Intestinal and Systemic Immune Responses in Infected Secondary Abiotic IL-10 Deficient Mice
Protease Activity of Campylobacter jejuni HtrA Modulates Distinct Intestinal and Systemic Immune Responses in Infected Secondary Abiotic IL-10 Deficient Mice
复制标题
DOI：
10.3389/fcimb.2019.00079
复制
发表时间：
2019-03
影响因子：
5.7
通讯作者：
Anna-Maria Schmidt;U. Escher;S. Mousavi;M. Boehm;S. Backert;S. Bereswill;M. Heimesaat
中科院分区：
文献类型：
--
作者：
Anna-Maria Schmidt;U. Escher;S. Mousavi;M. Boehm;S. Backert;S. Bereswill;M. Heimesaat
尽管人类空肠弯曲菌感染在全球范围内逐渐增加，但病原体-宿主-相互作用的潜在分子机制仍不完全清楚。我们最近发现分泌型丝氨酸蛋白酶HtrA在空肠弯曲菌体外细胞侵袭和跨上皮迁移中起关键作用，并参与体内感染模型小鼠肠道病理的发生。在本研究中，我们研究了HtrA的蛋白水解酶活性在空肠弯曲菌诱导的急性小肠结肠炎中的作用。为此，我们用空肠弯曲菌野生型菌株NCTC11168(11168WT)或活性中心S197A单点突变(11168HtrA-S197A)的携带蛋白酶失活HtrA的同源细菌(11168HtrA-S197A)口服感染继发性非生物IL-10-/-小鼠。无论应用哪种致病菌株，小鼠的粪便中都有类似的空肠弯曲菌负荷，并在感染后第6天(P.I.)表现出相对严重的急性小肠结肠炎的肉眼症状。有趣的是，与感染11168WT菌株的对照组相比，感染11168HtrA-S197A的小鼠表现出较不明显的结肠细胞凋亡和免疫细胞反应，但促进了上皮细胞的增殖。此外，与亲本株相比，11168HtrA-S197A感染的小鼠在显微镜下的后遗症不明显，前者与后者相比，结肠内分泌的促炎细胞因子如单核细胞趋化蛋白-1、IL-6、肿瘤坏死因子和干扰素-γ较少。值得注意的是，S197A点突变还与血清样本中评估的较不明显的全身性促炎免疫反应有关。综上所述，HtrA是空肠弯曲菌一种新的毒力决定因子，其蛋白酶活性不是肠道定植和疾病发生所必需的，而是通过触发细胞凋亡和促炎免疫反应而加重弯曲杆菌病。
Even though human Campylobacter jejuni infections are progressively increasing worldwide, the underlying molecular mechanisms of pathogen-host-interactions are still not fully understood. We have recently shown that the secreted serine protease HtrA plays a key role in C. jejuni cellular invasion and transepithelial migration in vitro, and is involved in the onset of intestinal pathology in murine infection models in vivo. In the present study, we investigated whether the protease activity of HtrA had an impact in C. jejuni induced acute enterocolitis. For this purpose, we perorally infected secondary abiotic IL-10-/- mice with wildtype C. jejuni strain NCTC11168 (11168WT) or isogenic bacteria carrying protease-inactive HtrA with a single point mutation at S197A in the active center (11168HtrA-S197A). Irrespective of the applied pathogenic strain, mice harbored similar C. jejuni loads in their feces and exhibited comparably severe macroscopic signs of acute enterocolitis at day 6 postinfection (p.i.). Interestingly, the 11168HtrA-S197A infected mice displayed less pronounced colonic apoptosis and immune cell responses, but enhanced epithelial proliferation as compared to the 11168WT strain infected controls. Furthermore, less distinct microscopic sequelae in 11168HtrA-S197A as compared to parental strain infected mice were accompanied by less distinct colonic secretion of pro-inflammatory cytokines such as MCP-1, IL-6, TNF, and IFN-γ in the former as compared to the latter. Strikingly, the S197A point mutation was additionally associated with less pronounced systemic pro-inflammatory immune responses as assessed in serum samples. In conclusion, HtrA is a remarkable novel virulence determinant of C. jejuni, whose protease activity is not required for intestinal colonization and establishment of disease, but aggravates campylobacteriosis by triggering apoptosis and pro-inflammatory immune responses.