Helicobacter pylori-derived outer membrane vesicles induce activation of primary human monocytes

Description

Helicobacter pylori (H. pylori) is a gram-negative bacterium, chronically infecting the human gastric mucosa. Due to its prevalence in approximately 50% of the world"s population and its well-described carcinogenic properties, it has been classified as a group I carcinogen. Since active suppression of the immune system by H. pylori is assumed to contribute critically to the chronicity of infection and bacterial outer membrane vesicles (OMVs) have previously been described to be loaded with immunomodulatory cargo, we hypothesized that H. pylori-derived OMVs may be causally involved in the chronic nature of H.
pylori colonization. To investigate the immunological consequences of primary human monocyte exposure to H. pylorioriginating OMVs, changes in cytokine and chemokine secretion, expression of surface markers and cell morphology were examined. In addition to strong upregulation of chemotactic protein secretion, OMVs considerably increased extracellular levels of specific cytokines and soluble adhesion molecules. Additionally, a strong increase of co-inhibitory protein PD-L1 expression was found to be induced, indicative of the involvement of the OMVs in the suppression of the adaptive arm of the immune system. The most profound effects of the bacterial vesicles, however, were observed on monocyte morphology. Upon stimulation with OMVs, monocytes acquired a highly dynamic, elongated shape, suggesting a strong increase in adhesive capacity. These phenotypic adaptations might support transmigration of immune cells from the circulation into the peripheral tissue. Conclusively, these data, demonstrating significant OMV-induced changes in secretory profile, expression of surface markers, and morphology of primary human monocytes, support the hypothesis of an immunoregulatory involvement of H. pylori-derived outer membrane vesicles during infection.

Period	2 Dec 2023 → 5 Dec 2023
Event title	Helicobacter pylori: genomics, signaling and carcinogenesis conference (HGSC 2023)
Event type	Conference
Location	Beilngries, Germany, BavariaShow on map
Degree of Recognition	International