Natural killer (NK) cell-derived extracellular-vesicle shuttled microRNAs control T cell responses.

Natural killer (NK) cells recognize and kill target cells undergoing different types of stress. NK cells are also capable of modulating immune responses. In particular, they regulate T cell functions. Small RNA next-generation sequencing of resting and activated human NK cells and their secreted extracellular vesicles (EVs) led to the identification of a specific repertoire of NK-EV-associated microRNAs and their post-transcriptional modifications signature. Several microRNAs of NK-EVs, namely miR-10b-5p, miR-92a-3p, and miR-155-5p, specifically target molecules involved in Th1 responses. NK-EVs promote the downregulation of GATA3 mRNA in CD4+ T cells and subsequent TBX21 de-repression that leads to Th1 polarization and IFN-γ and IL-2 production. NK-EVs also have an effect on monocyte and moDCs (monocyte-derived dendritic cells) function, driving their activation and increased presentation and costimulatory functions. Nanoparticle-delivered NK-EV microRNAs partially recapitulate NK-EV effects in mice. Our results provide new insights on the immunomodulatory roles of NK-EVs that may help to improve their use as immunotherapeutic tools.This manuscript was funded by grants PDI-2020-120412RB-I00 and PDC2021- 121719-I00 (FS-M) and PID2020- 119352RB-I00 (AS) from the Spanish Ministry of Economy and Competitiveness; CAM (S2017/BMD3671-INFLAMUNE-CM) from the Comunidad de Madrid (FS-M). CIBERCV (CB16/11/00272) and BIOIMID PIE13/041 from the Instituto de Salud Carlos. The current research has received funding from 'la Caixa' Foundation under the project code HR17-00016. Grants from Ramón Areces Foundation 'Ciencias de la Vida y de la Salud' (XIX Concurso-2018) and from Ayuda Fundación BBVA y Equipo de Investigación Científica (BIOMEDICINA-2018) (to FSM). The CNIC is supported by the Ministerio de Ciencia, Innovacion y Universidades and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015–0505). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, CEX2020-001039-S). SGD is supported by a grant from the Spanish Ministry of Universities. Authors thank Dr Miguel Vicente-Manzanares for critical review and editing. We also thank Dr Francisco Urbano and Dr Covadonga Aguado for their support with EM (TEM facilities, Universidad Autónoma de Madrid).S

Immune evasion by proteolytic shedding of natural killer group 2, member D ligands in Helicobacter pylori infection

BackgroundHelicobacter pylori (H. pylori) uses various strategies that attenuate mucosal immunity to ensure its persistence in the stomach. We recently found evidence that H. pylori might modulate the natural killer group 2, member 2 (NKG2D) system. The NKG2D receptor and its ligands are a major activation system of natural killer and cytotoxic T cells, which are important for mucosal immunity and tumor immunosurveillance. The NKG2D system allows recognition and elimination of infected and transformed cells, however viruses and cancers often subvert its activation. Here we aimed to identify a potential evasion of the NKG2D system in H. pylori infection.MethodsWe analyzed expression of NKG2D system genes in gastric tissues of H. pylori gastritis and gastric cancer patients, and performed cell-culture based infection experiments using H. pylori isogenic mutants and epithelial and NK cell lines.ResultsIn biopsies of H. pylori gastritis patients, NKG2D receptor expression was reduced while NKG2D ligands accumulated in the lamina propria, suggesting NKG2D evasion. In vitro, H. pylori induced the transcription and proteolytic shedding of NKG2D ligands in stomach epithelial cells, and these effects were associated with specific H. pylori virulence factors. The H. pylori-driven release of soluble NKG2D ligands reduced the immunogenic visibility of infected cells and attenuated the cytotoxic activity of effector immune cells, specifically the anti-tumor activity of NK cells.ConclusionH. pylori manipulates the NKG2D system. This so far unrecognized strategy of immune evasion by H. pylori could potentially facilitate chronic bacterial persistence and might also promote stomach cancer development by allowing transformed cells to escape immune recognition and grow unimpeded to overt malignancy

Interaccion entre los receptores p58/p50 de las celulas NK y sus ligandos

Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai