Dancing with the Stars: How Choreographed Bacterial Interactions Dictate Nososymbiocity and Give Rise to Keystone Pathogens, Accessory Pathogens, and Pathobionts

• Published in: Trends in microbiology (Regular ed.) 2016-06, Vol.24 (6), p.477-489
• Main Authors: Hajishengallis, George, Lamont, Richard J
• Format: Article
• Language: English
• Subjects: accessory pathogen; Bacteria; Bacteria - immunology; Bacteria - metabolism; Bacteria - pathogenicity; Bacterial Infections - immunology; Bacterial Infections - microbiology; biochemical pathways; chemical communication; communications technology; Dysbiosis; homeostasis; Homeostasis - immunology; Host-Pathogen Interactions - immunology; Host-Pathogen Interactions - physiology; Humans; Immunity; Inflammation - immunology; Inflammation - microbiology; Inflammation - pathology; Internal Medicine; keystone pathogen; microbial communities; Microbial Consortia - immunology; Microbial Consortia - physiology; Microbial Interactions - immunology; Microbial Interactions - physiology; Mucous Membrane - immunology; Mucous Membrane - microbiology; nososymbiocity; pathobiont; pathogenicity; pathogens; polymicrobial synergy; Symbiosis - physiology
• ISSN: 0966-842X; 1878-4380
• DOI: 10.1016/j.tim.2016.02.010

Many diseases that originate on mucosal membranes ensue from the action of polymicrobial communities of indigenous organisms working in concert to disrupt homeostatic mechanisms. Multilevel physical and chemical communication systems among constituent organisms underlie polymicrobial synergy and dictate the community's pathogenic potential or nososymbiocity, that is, disease arising from living together with a susceptible host. Functional specialization of community participants, often originating from metabolic codependence, has given rise to several newly appreciated designations within the commensal-to-pathogen spectrum. Accessory pathogens, while inherently commensal in a particular microenvironment, nonetheless enhance the colonization or metabolic activity of pathogens. Keystone pathogens (bacterial drivers or alpha-bugs) exert their influence at low abundance by modulating both the composition and levels of community participants and by manipulating host responses. Pathobionts (or bacterial passengers) exploit disrupted host homeostasis to flourish and promote inflammatory disease. In this review we discuss how commensal or pathogenic properties of organisms are not intrinsic features, and have to be considered within the context of both the microbial community in which they reside and the host immune status.