[ODP2A] a. 生態・共生・環境微生物

[ODP-008/WS4-7] 腸管リンパ組織内細菌アルカリゲネスと樹状細胞の共生関係

○細見 晃司¹，柴田 納央子^1,2,3，下山 敦史⁴，宇戸 智哉⁴，長竹 貴広¹，竹山 春子³，深瀬 浩一⁴，清野 宏²，國澤 純^1,2,3,4,5 (¹医薬基盤・健康・栄養研究所，²東京大学，³早稲田大学，⁴大阪大学，⁵神戸大学)

We previously found unique bacterial communities inside intestinal lymphoid tissues including Peyer’s patches (PPs). Alcaligenes spp. including A. faecalis are a dominant genus among lymphoid-tissue-resident commensal bacteria (LRCs). LRCs modulate the host immune system including intestinal IgA production through persisting in dendritic cells (DCs) in the PPs without inducing an excessive inflammatory response. Here, we show Alcaligenes establish an intracellular symbiotic relationship with DCs and this symbiosis induces a unique energy metabolic shift in DCs that are associated with less induction of apoptosis. DCs showed reduced levels of mitochondrial respiration when they were co-cultured with non-symbiotic E. coli, whereas DCs carrying A. faecalis maintained high levels of mitochondrial respiration. Furthermore, E. coli induced apoptosis of DCs, while A. faecalis did not. An underlying mechanism included a different activity in the induction of intracellular nitric oxide (NO) production due to the different activity of LPS. E. coli induced high levels of NO production that inhibited mitochondrial function, in contrast, A. faecalis elicited little NO production in DCs, resulting in the low rate of apoptosis together with the increased mitochondrial respiration. These are novel symbiotic mechanisms of LRCs including A. faecalis in PPs.