CYLD-TRAF6 interaction promotes ADP-heptose-induced NF-κB signaling in H. pylori infection.

The inflammatory response associated with Helicobacter pylori (H. pylori) infection causes a multitude of alterations in the gastric microenvironment, leading to the slow and steady disruption of the gastric epithelial barrier. Activation of NF-κB during H. pylori infection is crucial to this inflammatory response. Here, we show that CYLD, which interacts constitutively with TRAF6, enhances H. pylori's ADP-heptose-induced activation of the classical NF-κB pathway in gastric epithelial cells. This activating effect of CYLD contrasts with the inhibitory effect of CYLD on receptor-mediated NF-κB activity. Mechanistically, CYLD counteracts the hydrolysis of ubiquitin chains from TRAF6 by deubiquitinylase A20 in a catalytically independent manner, thus supporting the auto-ubiquitinylation of TRAF6 upon activation of NF-κB in early H. pylori infection. In addition, the subsequent classical NF-κB-dependent de novo synthesis of A20 provides a negative feedback loop leading to shutdown not only of the classical but also of the alternative NF-κB pathway. Our findings highlight the regulatory relationship between CYLD and A20 in controlling classical as well as alternative NF-κB signaling in H. pylori infection.