Salmonella pathogenicity island 1 differentially modulates bacterial entry to dendritic and non-phagocytic cells

Immunology. 2010 Jun;130(2):273-87. doi: 10.1111/j.1365-2567.2009.03233.x. Epub 2010 Feb 26.

Abstract

Salmonella enterica serovar Typhimurium can enter non-phagocytic cells, such as intestinal epithelial cells, by virtue of a Type Three Secretion System (TTSS) encoded in the Salmonella Pathogenicity Island 1 (SPI-1), which translocates bacterial effector molecules into the host cell. Salmonella can also be taken up by dendritic cells (DCs). Although the role of SPI-1 in non-phagocytic cell invasion is well established, its contribution to invasion of phagocytic cells has not been evaluated. Here, we have tested the invasive capacity of a S. Typhimurium strain lacking a key component of its TTSS-1 (DeltaInvC) leading to defective translocation of SPI-1-encoded effectors. Whereas this mutant Salmonella strain was impaired for invasion of non-phagocytic cells, it was taken up by DCs at a significantly higher rate than wild-type Salmonella. Similar to wild-type Salmonella, the DeltaInvC mutant strain retained the capacity to avoid antigen presentation to T cells. However, mice infected with the DeltaInvC mutant strain showed higher survival rate and reduced organ colonization. Our data suggest that, besides promoting phagocytosis by non-phagocytic cells, SPI-1 modulates the number of bacteria that enters DCs. The SPI-1 could be considered not only as an inducer of epithelial cell invasion but as a controller of DC entry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen Presentation / genetics
  • Antigen Presentation / immunology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology*
  • Bacterial Proteins / metabolism
  • Bacterial Translocation / genetics
  • Bacterial Translocation / immunology*
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism
  • Dendritic Cells / microbiology
  • Epithelial Cells / immunology*
  • Epithelial Cells / metabolism
  • Epithelial Cells / microbiology
  • Gene Deletion
  • Mice
  • Mice, Transgenic
  • Phagocytosis / genetics
  • Phagocytosis / immunology
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / immunology*
  • Salmonella typhimurium / metabolism
  • Salmonella typhimurium / pathogenicity*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • T-Lymphocytes / microbiology

Substances

  • Bacterial Proteins
  • Spi1 protein, Salmonella