Uncoupling of invasive bacterial mucosal immunogenicity from pathogenicity

Nat Commun. 2020 Apr 24;11(1):1978. doi: 10.1038/s41467-020-15891-9.

Abstract

There is the notion that infection with a virulent intestinal pathogen induces generally stronger mucosal adaptive immunity than the exposure to an avirulent strain. Whether the associated mucosal inflammation is important or redundant for effective induction of immunity is, however, still unclear. Here we use a model of auxotrophic Salmonella infection in germ-free mice to show that live bacterial virulence factor-driven immunogenicity can be uncoupled from inflammatory pathogenicity. Although live auxotrophic Salmonella no longer causes inflammation, its mucosal virulence factors remain the main drivers of protective mucosal immunity; virulence factor-deficient, like killed, bacteria show reduced efficacy. Assessing the involvement of innate pathogen sensing mechanisms, we show MYD88/TRIF, Caspase-1/Caspase-11 inflammasome, and NOD1/NOD2 nodosome signaling to be individually redundant. In colonized animals we show that microbiota metabolite cross-feeding may recover intestinal luminal colonization but not pathogenicity. Consequent immunoglobulin A immunity and microbial niche competition synergistically protect against Salmonella wild-type infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism
  • Animals
  • Antigens, Bacterial
  • Caspase 1 / metabolism
  • Caspases, Initiator / metabolism
  • Cell Proliferation
  • Gastrointestinal Microbiome
  • Immunity, Innate
  • Immunity, Mucosal*
  • Immunoglobulin A / immunology
  • Inflammation
  • Intestinal Mucosa / microbiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred NOD
  • Myeloid Differentiation Factor 88 / metabolism
  • Nod1 Signaling Adaptor Protein / metabolism
  • Nod2 Signaling Adaptor Protein / metabolism
  • Salmonella Infections / microbiology*
  • Salmonella typhimurium / pathogenicity
  • Signal Transduction
  • Virulence
  • Virulence Factors

Substances

  • Adaptor Proteins, Vesicular Transport
  • Antigens, Bacterial
  • Immunoglobulin A
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • Nod1 Signaling Adaptor Protein
  • Nod1 protein, mouse
  • Nod2 Signaling Adaptor Protein
  • Nod2 protein, mouse
  • TICAM-1 protein, mouse
  • Virulence Factors
  • Casp4 protein, mouse
  • Caspases, Initiator
  • Casp1 protein, mouse
  • Caspase 1