Project description:The innate immune system is crucial for eventual control of infections, but may also contribute to pathology. Listeria monocytogenes is an intracellular gram-positive bacteria and a major cause of food-borne disease. However, important knowledge on the interactions between L. monocytogenes and the immune system is still missing. Here we report that Listeria DNA is sorted into extracellular vesicles (EV)s in infected cells and delivered to bystander cells to stimulate the cGAS-STING pathway. This was also observed during infections with Francisella tularensis and Legionella pneumophila. We identify the multivesicular body protein MVB12b as a target for TBK1 phosphorylation, which is essential for sorting of DNA into EVs and stimulation of bystander cells. EVs from Listeria-infected cells inhibited T cell proliferation, and primed T cells for apoptosis. Collectively, we describe a novel pathway for EV-mediated delivery of foreign DNA to bystander cells, and suggest that intracellular bacteria exploit this pathway to impair anti-bacterial defense.
Project description:We infected wild type L. monocytogenes EGD-e (1) and its isogenic deltahlydeltaplcA (2) (lacking the ability to breach the vacuolar compartment of host cells following uptake) mutant strain to human intestinal epithelial cell line (Caco-2) with an MOI of 100 and 500 respectively. Bacterial total RNA was isolated at 1 h (deltahlydeltaplcA) and 4 h (EGD-e) post infection, reverse transcribed, hybridised to whole genome microarray and microarray data was analysed as described previously (3) 1. Glaser et al. 2001. Comparative genomics of Listeria species. Science 294:849-852. 2. Paschen et al. 2000. Human dendritic cells infected by Listeria monocytogenes: induction of maturation, requirements for phagolysosomal escape and antigen presentation capacity. Eur.J.Immunol. 30:3447-3456. 3. Chatterjee et al. 2006. Intracellular gene expression profile of Listeria monocytogenes. Infect.Immun. 74:1323-1338.
Project description:Secreted bacterial RNAs have recently emerged as a novel host-pathogen interaction mode. Naked RNA molecules are highly labile in the extracellular environment and must be protected by packaging into membrane vesicles or into complexes with RNA binding proteins. RNA secretion through membrane vesicles has been shown for several bacterial species but, surprisingly, proteins that bind and stabilize bacterial RNAs in the extracellular environment have not been reported yet. Here, we show that the bacterial pathogen L. monocytogenes secretes a small RNA binding protein that we named Zea. We show that Zea binds and stabilizes a subset of L. monocytogenes RNA, causing its accumulation in the extracellular medium. Zea modulates L. monocytogenes in vivo. Furthemore, Zea binds the mammalian non-self-RNA innate immunity sensor RIG-I and potentiates RIG-I-signaling during infection. This study provides a mechanism for the stability of extracellular RNA and unveils how secreted bacterial RNAs participate in the host-pathogen crosstalk.
Project description:Investigation of whole genome gene expression level changes in Listeria monocytogenes LO28 delta-lhrC1-5 mutant, compared to the wild type strain. The lhrC1-5 genes encode the regulatory sRNAs LhrC1-5. The microarray studied the gene expression of unstressed cells and cells exposed to cefuroxime for 30 min. The lhrC1-5 mutant employed in this study is further described in Sievers et al. (2014) A multicopy sRNA of Listeria monocytogenes regulates expression of the virulence adhesin LapB. Nucleic Acids Res. 42:9383-98.
Project description:This study will evaluate the safety and tolerability of a personalized live, attenuated, double-deleted Listeria monocytogenes (pLADD) treatment in adults with metastatic colorectal cancer.