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Updated: Aug 13, 2026
The Utilization of Oropharyngeal Intratracheal PAMP Administration and Bronchoalveolar Lavage to Evaluate the Host Immune Response in Mice
Published on: April 3, 2014
Roles of interleukin-6 and macrophage inflammatory protein-2 in pneumolysin-induced lung inflammation in mice
Anita W Rijneveld1, Germie P van den Dobbelsteen, Sandrine Florquin
1Department of Experimental Internal Medicine, Tropical Medicine, and AIDS, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands. a.w.rijneveld@amc.uva.nl
Abstract:
Pneumolysin (PLY), a toxin synthesized by Streptococcus pneumoniae, is an important virulence factor in pneumococcal disease. This study evaluated the effects of PLY in lungs of mice. Intranasal inoculation with PLY was associated with a dose-dependent influx of polymorphonuclear leukocytes (PMNL) in bronchoalveolar lavage fluid (BALF) and increased concentrations of interleukin (IL)-6, macrophage inflammatory protein (MIP)-2, and KC in BALF. PLY mutants with either reduced cytolytic activity or reduced cytolytic and complement-activating activities were less potent in inducing PMNL recruitment to the lung (P<.05), which suggests that PLY cytolytic activity is very important for the inflammatory response. IL-6 and MIP-2 also played a role in PLY-induced PMNL recruitment; this response was partially diminished in IL-6 gene-deficient mice and in mice treated with anti-MIP-2 antiserum. PLY may play an important role in the induction of an inflammatory response in the pulmonary compartment in the early phase of pneumococcal pneumonia.
Insights
Pneumolysin (PLY) from Streptococcus pneumoniae drives lung inflammation by increasing white blood cells and inflammatory signals. Its cytolytic activity is crucial for this response in pneumococcal pneumonia.
Area of Science:
- Immunology
- Microbiology
- Pulmonology
Background:
- * Streptococcus pneumoniae is a leading cause of pneumonia.
- * Pneumolysin (PLY) is a key toxin and virulence factor of S. pneumoniae.
- * Understanding PLY's role in lung inflammation is critical for disease management.
Purpose of the Study:
- * To investigate the effects of pneumolysin (PLY) on the pulmonary inflammatory response in a mouse model.
- * To determine the contribution of PLY's cytolytic activity to lung inflammation.
- * To elucidate the roles of specific cytokines (IL-6, MIP-2) in PLY-induced inflammation.
Main Methods:
- * Intranasal inoculation of mice with varying doses of wild-type PLY and PLY mutants.
- * Analysis of bronchoalveolar lavage fluid (BALF) for polymorphonuclear leukocytes (PMNL) and cytokine concentrations (IL-6, MIP-2, KC).
- * Assessment of PLY-induced inflammation in IL-6 gene-deficient mice and mice treated with anti-MIP-2 antiserum.
Main Results:
- * PLY induced a dose-dependent influx of PMNL and increased levels of IL-6, MIP-2, and KC in BALF.
- * PLY mutants with reduced cytolytic activity showed diminished PMNL recruitment.
- * Depletion of IL-6 or MIP-2 partially reduced the PLY-induced PMNL response.
Conclusions:
- * PLY's cytolytic activity is essential for inducing PMNL recruitment in the lungs.
- * IL-6 and MIP-2 contribute to the inflammatory response mediated by PLY.
- * PLY plays a significant role in initiating pulmonary inflammation during early pneumococcal pneumonia.
