Project description:Cationic antimicrobial peptides (CAPs) are promising novel alternatives to conventional antibacterial agents, but the overlap in resistance mechanisms between small-molecule antibiotics and CAPs is unknown. Does evolution of antibiotic resistance decrease (cross-resistance) or increase (collateral sensitivity) susceptibility to CAPs? We systematically addressed this issue by studying the susceptibilities of a comprehensive set of antibiotic resistant Escherichia coli strains towards 24 antimicrobial peptides. Strikingly, antibiotic resistant bacteria frequently showed collateral sensitivity to CAPs, while cross-resistance was relatively rare. We identified clinically relevant multidrug resistance mutations that simultaneously elevate susceptibility to certain CAPs. Transcriptome and chemogenomic analysis revealed that such mutations frequently alter the lipopolysaccharide composition of the outer cell membrane and thereby increase the killing efficiency of membrane-interacting antimicrobial peptides. Furthermore, we identified CAP-antibiotic combinations that rescue the activity of existing antibiotics and slow down the evolution of resistance to antibiotics. Our work provides a proof of principle for the development of peptide based antibiotic adjuvants that enhance antibiotic action and block evolution of resistance.
2018-03-29 | GSE96706 | GEO
Project description:Gut microbiome of clinically relevant diseases
Project description:Background: Probiotic-like bacteria treatment has been described to be associated with gut microbiota modifications. Goal: To decipher if the effects of the tested probiotic-like bacteria are due to the bacteria itself or due to the effects of the bacteria on the gut microbiota. Methodology: In this study, gut microbiota has been analyzed from feces samples of subjects with metabolic syndrome and treated with one of the 2 tested probiotic-like bacteria or with the placebo during 3months.
Project description:Bacteria-based cancer immunotherapy, dated back to Coley’s toxins (inactivated bacteria) in 1893, has recently regained substantial attentions, usually by using attenuated bacteria to transform immune-silent “cold” tumors into immune-inflamed “hot” ones. However, while inactivated bacteria showed limited antitumor efficacy, attenuated live bacteria often possessed significant safety risks. Herein, by biomineralizing growth of manganese dioxide on the surface of paraformaldehyde-fixed gram-negative Salmonella typhimurium (S. typhimurium), we obtained MnO2-coated fixed S. typhimurium (M@F.S), which showed potent immune-stimulating effects via activating multiple pathways including Toll-like receptors (TLRs), cyclic GMP-AMP Synthase (cGAS)-stimulator of interferon genes (STING) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs). Single intratumoral administration of M@F.S at safe doses resulted in surprisingly strong efficacies in suppressing various types of mouse tumor models and a rabbit cancer model, and the cured mice and rabbits gained immune memory to reject re-challenged tumors. An abscopal antitumor effect was also observed, suggesting systemic antitumor immunity triggered by local injection of M@F.S. The antitumor mechanisms of M@F.S were preliminarily demonstrated to be innate immune activation initiated by multiple signaling pathways, followed by subsequent activation of tumor-specific immune responses, together with the modulation of immunosuppressive tumor microenvironment. We further demonstrated the efficacy of biomineralized bacteria in inhibiting an orthotopic breast tumor model established on tree shrews, an alternative animal model to primates with better clinical relevance. Such oncolytic biomineralized bacteria could be a potent yet safe immunotherapeutic agent for treatment of various solid tumors.