Ando-Suguimoto Ellen S, Benakanakere Manjunatha R, Mayer Marcia P A, Kinane Denis F
Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-020, Brazil.
Department of Periodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Pathogens. 2020 Mar 27;9(4):248. doi: 10.3390/pathogens9040248.
In aggressive periodontitis, the dysbiotic microbial community in the subgingival crevice, which is abundant in Aggregatibacter actinomycetemcomitans, interacts with extra- and intracellular receptors of host cells, leading to exacerbated inflammation and subsequent tissue destruction. Our goal was to understand the innate immune interactions of A. actinomycetemcomitans with macrophages and human gingival epithelial cells (HGECs) on the signaling cascade involved in inflammasome and inflammatory responses. U937 macrophages and HGECs were co-cultured with A. actinomycetemcomitans strain Y4 and key signaling pathways were analyzed using real-time PCR, Western blotting and cytokine production by ELISA. A. actinomycetemcomitans infection upregulated the transcription of TLR2, TLR4, NOD2 and NLRP3 in U937 macrophages, but not in HGECs. Transcription of IL-1β and IL-18 was upregulated in macrophages and HGECs after 1 h interaction with A. actinomycetemcomitans, but positive regulation persisted only in macrophages, resulting in the presence of IL-1β in macrophage supernatant. Immunoblot data revealed that A. actinomycetemcomitans induced the phosphorylation of AKT and ERK1/2, possibly leading to activation of the NF-κB pathway in macrophages. On the other hand, HGEC signaling induced by A. actinomycetemcomitans was distinct, since AKT and 4EBP1 were phosphorylated after stimulation with A. actinomycetemcomitans, whereas ERK1/2 was not. Furthermore, A. actinomycetemcomitans was able to induce the cleavage of caspase-1 in U937 macrophages in an NRLP3-dependent pathway. Differences in host cell responses, such as those seen between HGECs and macrophages, suggested that survival of A. actinomycetemcomitans in periodontal tissues may be favored by its ability to differentially activate host cells.
在侵袭性牙周炎中，龈下裂隙中以伴放线聚集杆菌为主的失调微生物群落与宿主细胞的细胞外和细胞内受体相互作用，导致炎症加剧和随后的组织破坏。我们的目标是了解伴放线聚集杆菌与巨噬细胞和人牙龈上皮细胞（HGECs）在炎性小体和炎症反应相关信号级联上的天然免疫相互作用。将U937巨噬细胞和HGECs与伴放线聚集杆菌Y4菌株共培养，并使用实时PCR、蛋白质印迹法和ELISA检测细胞因子产生情况来分析关键信号通路。伴放线聚集杆菌感染上调了U937巨噬细胞中TLR2、TLR4、NOD2和NLRP3的转录，但在HGECs中未上调。与伴放线聚集杆菌相互作用1小时后，巨噬细胞和HGECs中IL-1β和IL-18的转录上调，但仅在巨噬细胞中持续存在正调控，导致巨噬细胞上清液中存在IL-1β。免疫印迹数据显示，伴放线聚集杆菌诱导了AKT和ERK1/2的磷酸化，可能导致巨噬细胞中NF-κB通路的激活。另一方面，伴放线聚集杆菌诱导的HGEC信号传导是不同的，因为用伴放线聚集杆菌刺激后AKT和4EBP1被磷酸化，而ERK1/2未被磷酸化。此外，伴放线聚集杆菌能够通过NRLP3依赖的途径诱导U937巨噬细胞中caspase-1的裂解。宿主细胞反应的差异，如在HGECs和巨噬细胞之间观察到的差异，表明伴放线聚集杆菌在牙周组织中的存活可能因其差异激活宿主细胞的能力而受到青睐。
