Apyrase-mediated amplification of secretory IgA promotes intestinal homeostasis

Morphogenesis of epithelial tissues relies on the precise developmental control of cell polarity and architecture. In the early Drosophila embryo, the primarSecretory IgA (SIgA) interaction with commensal bacteria regulates the composition and function of the microbiota, contributing to gut ecosystem homeostasis. However, mechanisms regulating the reciprocal control of microbiota and SIgA are not defined. Bacteria-derived ATP limits T follicular helper (Tfh) cells activity in the Peyer’s patches (Pps) of the small intestine via the P2X7 receptor and thereby SIgA generation. Here we show that inhibition of bacteria derived ATP signaling by delivery of the ATP-degrading enzyme apyrase to the intestine results in the amplification of the SIgA repertoire. The enhanced breadth of SIgA in mice colonized with apyrase-releasing E. Coli conditioned topographical distribution of bacteria and expression of genes involved in metabolic versus immune functions in the intestinal epithelium. SIgA mediated conditioning of bacteria and enterocyte function was also reflected by selective differences in nutrients absorption in mice colonized with apyrase expressing bacteria. Hydrolysis of bacteria derived ATP was particularly helpful in restoring intestinal homeostasis via SIgA in antibiotics induced dysbiosis. Administration of apyrase expressing bacteria attenuated intestinal barrier impairment, glucose metabolism perturbation and susceptibility to infection by enteric pathogens induced by antibiotic treatments. Therefore, microbiota derived ATP regulates SIgA, and amplification of SIgA response by apyrase can be leveraged to restore intestinal fitness in dysbiotic conditions.y epithelium forms during cellularisation, following a tightly controlled genetic programme where specific sets of genes are up-regulated. Some of them, for instance, control membrane invagination between the nuclei anchored at the apical surface of the syncytium. We performed genome-wide expression profiling of small intestinal epithelium from GF mice colonized with E. colipApyr or E. colipBAD28. To evaluate the effect of bacteria-derived eATP on the epithelial transcriptional activity independently of SIgA coating of E. Coli, we performed the same analysis in epithelial cells isolated from gnotobiotic E. colipApyr or E. colipBAD28 C57BL/6 Igh-J-/- mice, which carry a deletion in the J segment of the Ig heavy chain locus and therefore are devoid of immunoglobulins.

上皮组织的形态发生依赖于对细胞极性与结构的精准发育调控。在早期果蝇（Drosophila）胚胎中，分泌型免疫球蛋白A（Secretory IgA, SIgA）与共生细菌的相互作用可调控微生物群的组成与功能，助力维持肠道生态系统稳态。然而，调控微生物群与分泌型免疫球蛋白A之间相互调控的机制尚未阐明。细菌来源的三磷酸腺苷（ATP）可通过P2X7受体抑制小肠派尔集合淋巴结（Peyer’s patches, PP）中滤泡辅助性T细胞（T follicular helper, Tfh）的活性，进而影响分泌型免疫球蛋白A的生成。本研究表明，通过向肠道递送ATP降解酶腺苷三磷酸酶（apyrase）以抑制细菌来源的ATP信号通路，可扩增分泌型免疫球蛋白A的抗体库。在定植表达并释放腺苷三磷酸酶的大肠杆菌（E. coli）的小鼠体内，分泌型免疫球蛋白A广度的增强可调控细菌的空间分布，以及肠上皮细胞中参与代谢与免疫功能的基因表达。分泌型免疫球蛋白A介导的细菌与肠上皮细胞功能调控，也可通过定植表达腺苷三磷酸酶的大肠杆菌的小鼠所表现出的营养吸收选择性差异得以体现。在抗生素诱导的肠道菌群失调状态下，细菌来源ATP的水解作用可通过分泌型免疫球蛋白A助力肠道稳态的恢复。定植表达腺苷三磷酸酶的大肠杆菌可减轻抗生素治疗所引发的肠道屏障损伤、葡萄糖代谢紊乱，以及对肠道病原体感染的易感性。因此，微生物群来源的ATP可调控分泌型免疫球蛋白A的生成，而通过腺苷三磷酸酶扩增分泌型免疫球蛋白A的应答反应，可用于恢复菌群失调状态下的肠道健康。上皮细胞在细胞化过程中形成，遵循一套严格调控的遗传程序，其中特定基因集被上调。例如，其中部分基因可控制锚定在合胞体顶端表面的细胞核之间的膜内陷。我们对定植有pApyr大肠杆菌（E. coli pApyr）或pBAD28大肠杆菌（E. coli pBAD28）的无菌（GF）小鼠的小肠上皮细胞进行了全基因组表达谱分析。为了在排除大肠杆菌被分泌型免疫球蛋白A包被的干扰的前提下，探究细菌来源的细胞外ATP（eATP）对上皮细胞转录活性的影响，我们从悉生的pApyr大肠杆菌、pBAD28大肠杆菌定植的C57BL/6 Igh-J-/-小鼠中分离上皮细胞进行了相同的分析——该小鼠品系的Ig重链基因座J段存在缺失，因此无法产生免疫球蛋白。