title: Attenuation of host NO production by MAMPs potentiates development of the host in the squid-vibrio symbiosis.
abstract: Bacterial pathogens typically upregulate the host's production of nitric oxide synthase (NOS) and nitric oxide (NO) as antimicrobial agents, a response that is often mediated by microbe-associated molecular patterns (MAMPs) of the pathogen. In contrast, previous studies of the beneficial Euprymna scolopes/Vibrio fischeri symbiosis demonstrated that symbiont colonization results in attenuation of host NOS/NO, which occurs in high levels in hatchling light organs. Here, we sought to determine whether V. fischeri MAMPs, specifically lipopolysaccharide (LPS) and the peptidoglycan derivative tracheal cytotoxin (TCT), attenuate NOS/NO, and whether this activity mediates the MAMPs-induced light organ morphogenesis. Using confocal microscopy, we characterized levels of NOS with immunocytochemistry and NO with a NO-specific fluorochrome. When added exogenously to seawater containing hatchling animals, V. fischeri LPS and TCT together, but not individually, induced normal NOS/NO attenuation. Further, V. fischeri mutants defective in TCT release did not. Experiments with NOS inhibitors and NO donors provided evidence that NO mediates apoptosis and morphogenesis associated with symbiont colonization. Attenuation of NOS/NO by LPS and TCT in the squid-vibrio symbiosis provides another example of how the host's response to MAMPs depends on the context. These data also provide a mechanism by which symbiont MAMPs regulate host development.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Altura
authors.forename: Eric
authors.initials: E
authors.lastname: Stabb
authors.forename: William
authors.initials: W
authors.lastname: Goldman
authors.forename: Michael
authors.initials: M
authors.lastname: Apicella
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: McFall-Ngai
mesh_terms: D048908:Aliivibrio fischeri / Q000502:physiology*; D000818:Animals; D049832:Decapodiformes / Q000033:anatomy & histology / Q000378:metabolism / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D008027:Light; D009024:Morphogenesis; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D013559:Symbiosis / Q000502:physiology*
chemical_list: D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase