Related Experiment Video

Updated: Aug 13, 2026

Screening Bioactive Nanoparticles in Phagocytic Immune Cells for Inhibitors of Toll-like Receptor Signaling
09:51

Screening Bioactive Nanoparticles in Phagocytic Immune Cells for Inhibitors of Toll-like Receptor Signaling

Published on: July 26, 2017

Pathogen-specific TLR signaling in mucosa: mutual contribution of microbial TLR agonists and virulence factors

Jean-Claude Sirard1, Mariela Bayardo, Arnaud Didierlaurent

  • 1INSERM, Avenir Anti-microbial mucosal Immunity - E364, Campus Pasteur - Lille, France. Jean-Claude.Sirard@ibl.fr

European Journal of Immunology
|February 3, 2006
PubMed

Insights

Toll-like receptor (TLR) signaling, crucial for immunity, is modulated by bacterial fimbriae during urinary tract infections. Uropathogenic E. coli (UPEC) fimbriae dictate specific TLR4 adaptor molecules, enabling pathogen recognition while tolerating commensals.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Microbe-associated molecular patterns (MAMPs) detected by Toll-like receptors (TLRs) initiate protective immunity.
  • Mucosal immune responses must distinguish between pathogens and commensals to prevent inflammation.
  • Uropathogenic Escherichia coli (UPEC) triggers innate immunity via TLR4 in a CD14-independent manner during urinary tract infections.

Purpose of the Study:

  • To investigate the role of UPEC virulence factors, specifically fimbriae, in modulating TLR4-mediated epithelial responses.
  • To elucidate how different UPEC fimbriae influence TLR4 signaling pathways and adaptor molecule recruitment.

Main Methods:

  • The study likely involved in vitro assays using epithelial cells and UPEC strains with defined fimbrial expression.
  • Analysis of TLR4 signaling pathway activation and adaptor molecule involvement in response to different UPEC fimbriae.

Main Results:

  • UPEC fimbriae are essential for inducing a TLR4-specific epithelial response.
  • The type of fimbriae expressed by UPEC determines the recruitment of distinct adaptor molecules in TLR4 signaling.
  • This suggests a mechanism where bacterial virulence factors act as co-receptors to fine-tune TLR responses.

Conclusions:

  • TLR responses are actively regulated by co-receptors, including receptors for bacterial virulence factors.
  • Pathogen-specific TLR stimulation, influenced by virulence factors like fimbriae, allows the host immune system to differentiate and tolerate commensal bacteria.
  • This provides a novel mechanism for maintaining mucosal homeostasis during infection.

More Related Videos

Induction of Intestinal Inflammation by Adoptive Transfer of CBir1 TCR Transgenic CD4+ T Cells to Immunodeficient Mice07:34

Induction of Intestinal Inflammation by Adoptive Transfer of CBir1 TCR Transgenic CD4+ T Cells to Immunodeficient Mice

Published on: December 16, 2021

Related Concept Videos

Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
Determinants of Bacterial Pathogenicity and Virulence01:20

Determinants of Bacterial Pathogenicity and Virulence

Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
Defense Against Bacterial Pathogens01:31

Defense Against Bacterial Pathogens

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Colonisation of Pathogens01:25

Colonisation of Pathogens

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
Gastritis II: Pathophysiology01:26

Gastritis II: Pathophysiology

The pathophysiology of gastritis begins with the colonization of the stomach lining by Helicobacter pylori (H. pylori). This bacterium spreads mainly via the oral-oral route through saliva or shared utensils, and can also be transmitted in overcrowded or unhygienic environments through contaminated water, despite its brief survival outside the body.ColonizationOnce ingested, H. pylori enters the stomach and begins colonization by navigating through the mucus layer lining the stomach wall. It...