TFF1 Induces Aggregation and Reduces Motility of Helicobacter pylori.

Gastric cancer is considered one of the most common malignancies in humans and Helicobacter pylori infection is the major environmental risk factor of gastric cancer development. Given the high spread of this bacterium whose infection is mostly asymptomatic, H. pylori colonization persists for a long time, becoming chronic and predisposing to malignant transformation. The first defensive barrier from bacterial infection is constituted by the gastric mucosa that secretes several protective factors, among which is the trefoil factor 1 (TFF1), that, as mucin 5AC, binds the bacterium. Even if the protective role of TFF1 is well-documented, the molecular mechanisms that confer a beneficial function to the interaction among TFF1 and H. pylori remain still unclear. Here we analyze the effects of this interaction on H. pylori at morphological and molecular levels by means of microscopic observation, chemiotaxis and motility assays and real-time PCR analysis. Our results show that TFF1 favors aggregation of H. pylori and significantly slows down the motility of the bacterium across the mucus. Such aggregates significantly reduce both flgE and flaB gene transcription compared with bacteria not incubated with TFF1. Finally, our results suggest that the interaction between TFF1 and the bacterium may explain the frequent persistence of H. pylori in the human host without inducing disease.

TFF1 Promotes EMT-Like Changes through an Auto-Induction Mechanism.

Trefoil factor 1 (TFF1) is a small secreted protein expressed in the gastrointestinal tract where, together with the other two members of its family, it plays an essential role in mucosal protection and repair against injury. The molecular mechanisms involved in the protective function of all three TFF proteins are not fully elucidated. In this paper, we investigated the role of TFF1 in epithelial to mesenchymal transition (EMT) events. The effects of TFF1 on cellular models in normoxia and/or hypoxia were evaluated by western blot, immunofluorescence, qRT-PCR and trans-well invasion assays. Luciferase reporter assays were used to assess the existence of an auto-regulatory mechanism of TFF1. The methylation status of TFF1 promoter was measured by high-resolution melting (HRM) analysis. We demonstrate a TFF1 auto-induction mechanism with the identification of a specific responsive element located between -583 and -212 bp of its promoter. Our results suggest that TFF1 can regulate its own expression in normoxic, as well as in hypoxic, conditions acting synergistically with the hypoxia-inducible factor 1 (HIF-1α) pathway. Functionally, this auto-induction mechanism seems to promote cell invasion and EMT-like modifications in vitro. Additionally, exogenously added human recombinant TFF1 protein was sufficient to observe similar effects. Together, these findings suggest that the hypoxic conditions, which can be induced by gastric injury, promote TFF1 up-regulation, strengthened by an auto-induction mechanism, and that the trefoil peptide takes part in the epithelial-mesenchymal transition events eventually triggered to repair the damage.

Low copper availability limits Helicobacter infection in mice.

Copper is an essential element for all living organisms; however, it becomes toxic at high concentrations due to its ability to participate in many redox reactions. This vital micronutrient balance plays an important role in the battle between host and pathogen, due to its use by the host to intoxicate pathogens. In this study, we explore the effects of copper deprivation on Helicobacter infection in mice using the copper chelator tetrathiomolybdate. Our results reveal that Helicobacter infection significantly reduces copper concentration in mice stomachs without affecting its circulating levels. Moreover, in copper-deprived mice, bacteria hardly colonize the epithelium and mice show less gastric damage in comparison with the infected ones. However, when the copper chelator is administered after infection, the condition of the mouse stomachs declines. This could be explained by the lower copper availability in tetrathiomolybdate-treated mice, which would reduce macrophages' action against the pathogen. In this scenario, we observe that the protective factor trefoil factor 1 is induced upon copper-deprived conditions, probably contributing to the inefficacy of infection, whereas, when the chelator is administered after infection, the gene is already silenced by bacteria and cannot be restored. In conclusion, our data suggest that Helicobacter takes advantage of gastric copper reducing its availability for the host and that copper levels have an impact on the outcome of infection.

Gastric TFF1 Expression from Acute to Chronic Helicobacter Infection.

TFF1, a mucin-associated secreted peptide of gastric mucous cells, is known as a protective agent for stomach epithelium under different stimuli, but its role upon Helicobacter infection is still not clear. In this paper we characterized TFFs expression, with particular attention to TFF1, under Helicobacter infection in gastric cell lines. A mouse model was used to distinguish TFF1 mRNA expression between acute and chronic stages of Helicobacter infection. Our results show that TFF1 expression is induced in infected cells; in addition, the inflammatory response upon Helicobacter infection is inversely associated to pre-existing TFF1 protein levels. In infected mice, TFF1 is initially upregulated in gastric antrum in the acute phase of infection, along with IL-1ß and IL-6. Then, expression of TFF1 is gradually silenced when the infection becomes chronic and IFN-γ, CXCL5, and CXCL15 reach higher levels. Our data suggest that TFF1 might help cells to counteract bacteria colonization and the development of a chronic inflammation.