Related Experiment Video

Updated: Sep 28, 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

Toll-like receptor 2 participates in mediation of immune response in experimental pneumococcal meningitis

Uwe Koedel1, Barbara Angele, Tobias Rupprecht

  • 1Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, Germany.

Journal of Immunology (Baltimore, Md. : 1950)
|December 24, 2002
PubMed

Insights

Toll-like receptor 2 (TLR2) plays a significant role in the immune response to pneumococcal meningitis. Mice lacking TLR2 exhibited increased disease severity and bacterial load, indicating its importance in host defense.

Area of Science:

  • Immunology
  • Microbiology
  • Neuroscience

Background:

  • Toll-like receptor 2 (TLR2) and CD14 mediate responses to pneumococcal peptidoglycan.
  • The role of TLR2 in pneumococcal meningitis pathogenesis requires further characterization.

Purpose of the Study:

  • To investigate the function of TLR2 in the host immune response to Streptococcus pneumoniae infection.
  • To determine the impact of TLR2 deficiency on the clinical course and severity of pneumococcal meningitis.

Main Methods:

  • Mice with targeted disruption of the TLR2 gene (TLR2-/-) were infected with Streptococcus pneumoniae.
  • Brain TLR2 mRNA expression was analyzed post-infection.
  • Disease severity, intracranial complications, body weight, temperature, motor impairment, and bacterial titers were assessed.
  • Expression of inflammatory mediators and complement inhibitors was measured.
  • HEK293 cells and peritoneal macrophages from TLR2/TLR4 deficient mice were used for in vitro analysis of NF-kappaB activation and TNF-alpha release.

Main Results:

  • Pneumococcal infection significantly increased brain TLR2 mRNA expression.
  • TLR2-/- mice showed aggravated meningitis, reduced body weight and temperature, motor impairment, and higher bacterial titers.
  • Expression of complement receptor-related protein y was elevated in infected TLR2-/- mice.
  • Expression of key inflammatory mediators (IL-1beta, TNF-alpha, IL-6, MIP-2, iNOS, C3) was similar between genotypes.
  • Overexpression of TLR2 and TLR4/MD-2 activated NF-kappaB in response to pneumococci.
  • Pneumococci-induced TNF-alpha release did not differ between wild-type and double-deficient macrophages.

Conclusions:

  • TLR2 plays a significant role in vivo during pneumococcal meningitis, influencing disease severity and bacterial clearance.
  • Despite TLR2's importance, other, yet undefined, pattern recognition receptors contribute to the host's initial defense against Streptococcus pneumoniae.

More Related Videos

Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages08:34

Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages

Published on: February 22, 2017

Fluorescence Assays for the Study of Mycobacterium tuberculosis Interaction with the Immune Receptor SLAMF107:42

Fluorescence Assays for the Study of Mycobacterium tuberculosis Interaction with the Immune Receptor SLAMF1

Published on: February 28, 2025

Related Concept Videos

Bacterial Meningitis II: Pathophysiology01:26

Bacterial Meningitis II: Pathophysiology

Bacterial meningitis typically begins when pathogens such as Neisseria meningitidis and Streptococcus pneumoniae colonize the nasopharynx and invade the bloodstream. This process is facilitated by bacterial virulence factors, such as polysaccharide capsules, which resist phagocytosis and complement-mediated killing. Less commonly, bacteria reach the central nervous system via contiguous spread from infections like otitis media or sinusitis, through congenital or acquired dural defects, or...
Bacterial Meningitis01:24

Bacterial Meningitis

Bacterial meningitis is a severe infectious disease involving inflammation of the meninges, the protective membranes surrounding the brain and spinal cord. It occurs when pathogenic bacteria cross the blood–brain barrier and enter the cerebrospinal fluid. Common causative organisms include Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b, Listeria monocytogenes, and Escherichia coli K1. The exact route of entry varies by pathogen and host condition.Routes of Entry...
T Cell Types and Functions01:24

T Cell Types and Functions

When T cells with CD4 markers are activated, they give rise to two types of effector cells: helper T cells and regulatory T cells. Meanwhile, T cells with CD8 markers differentiate into effector cytotoxic T cells. The differentiation of CD4 T cells into helper T cell subsets, such as Th1, Th2, and Th17 cells, is dependent on the antigen type, antigen-presenting cell, and regulatory cytokines.
Th1 cells stimulate dendritic cells to express necessary co-stimulatory molecules on their surfaces for...
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...
T Cell Activation and Clonal Selection01:22

T Cell Activation and Clonal Selection

T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...
B Cell Activation and Differentiation01:24

B Cell Activation and Differentiation

The adaptive immune response, a sophisticated defense mechanism, relies on the activation and differentiation of B lymphocytes, or B cells. These processes enable our bodies to mount a tailored response against specific pathogens such as bacteria, free virus particles, toxins, and parasites.
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...