Related Experiment Video

Updated: Jun 29, 2026

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
06:06

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43

Published on: September 11, 2020

Lysozyme M deficiency leads to an increased susceptibility to Streptococcus pneumoniae-induced otitis media

Jun Shimada1, Sung K Moon, Haa-Yung Lee

  • 1Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA, USA. Jasmd513@aol.com

BMC Infectious Diseases
|October 10, 2008
PubMed
Abstract

Insights

Lysozyme M is crucial for clearing pneumococcal infections in the middle ear. Its depletion increases susceptibility to otitis media and inflammation, suggesting potential therapeutic uses.

Area of Science:

  • Immunology
  • Microbiology
  • Otolaryngology

Background:

  • Lysozyme is a key innate immune molecule that degrades bacterial cell walls.
  • It is widely expressed in various species and tissues, including the mammalian middle ear.
  • The role of lysozyme in middle ear infections, specifically otitis media, requires further investigation.

Purpose of the Study:

  • To investigate the impact of lysozyme M depletion on the clearance of Streptococcus pneumoniae from the middle ear.
  • To assess the susceptibility of lysozyme M-deficient mice to pneumococcal otitis media.
  • To evaluate the expression and activity of lysozyme in the Eustachian tube.

Main Methods:

  • Immunohistochemistry to localize lysozyme M and P in the Eustachian tube.
  • Real-time quantitative RT-PCR and Western blotting to compare lysozyme expression in wild-type and lysozyme M-/- mice.
  • Muramidase and bactericidal activity assays to measure lysozyme function.
  • Transtympanic inoculation of S. pneumoniae to assess middle ear infection and inflammation.

Main Results:

  • Lysozyme M and P exhibit specific localization within the Eustachian tube.
  • Lysozyme M deficiency leads to compensatory upregulation of lysozyme P but decreased overall lysozyme activity.
  • Lysozyme M-deficient mice show increased susceptibility to S. pneumoniae infection, resulting in more severe middle ear inflammation.

Conclusions:

  • Lysozyme M plays a critical role in early-phase protection against middle ear pathogens.
  • Depletion of lysozyme M compromises the middle ear's defense against pneumococcal infection.
  • Exogenous lysozyme may hold potential as an adjuvant therapy for otitis media.

More Related Videos

A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness12:21

A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness

Published on: September 28, 2022

Related Concept Videos

Atypical Pneumonia01:14

Atypical Pneumonia

Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease include...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Lysosomal Hydrolases01:22

Lysosomal Hydrolases

Lysosomes are the site for the degradation of macromolecules and biological polymers released during membrane trafficking events such as secretory, endocytic, autophagic, and phagocytic pathways. The membrane-enclosed area of the lysosome, called the lumen, contains hydrolytic enzymes active in an acidic environment. These acid hydrolases are functional at a pH between 4.5 and 5 and are involved in cellular processes such as cell signaling, energy metabolism, restoration of the plasma membrane,...
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...
Streptococcal Pharyngitis01:27

Streptococcal Pharyngitis

Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
Formation of Lipopolysaccharides01:19

Formation of Lipopolysaccharides

Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin, triggering...