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Updated: May 28, 2026
A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice
Published on: September 28, 2016
Sex-based differences in susceptibility to respiratory and systemic pneumococcal disease in mice
Aras Kadioglu1, Anna Maria Cuppone, Claudia Trappetti
1Department of Infection, Immunity, and Inflammation, University of Leicester, United Kingdom.
Abstract:
Systemic infection with Streptococcus pneumoniae was investigated in male and female mice in models of invasive pneumonia and sepsis. Male mice were found to be more susceptible to infection, exhibiting greater weight loss, marked decrease in body temperature, and a significantly higher mortality rate compared with female mice. For pneumonia, there were significant differences in survival rates. Female mice cleared their lung infections over time, whereas male mice, compared with female mice, had significantly increased numbers of colony-forming units in early stages of infection accompanied by higher levels of neutrophil recruitment in the first 24 hours after infection. Importantly, there were significant increases in proinflammatory cytokine levels during both sepsis and pneumonia in male compared with female mice. These cytokines were indicative of T-helper 1-type responses. The data presented here describe surprising differences in survival rates, neutrophil recruitment, and proinflammatory cytokine levels, indicating a sex-based difference in susceptibility to respiratory and systemic pneumococcal disease.
Insights
Male mice show higher susceptibility to Streptococcus pneumoniae infections, experiencing greater weight loss and mortality in pneumonia and sepsis models compared to females. This sex-based difference is linked to immune responses and inflammation.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Streptococcus pneumoniae is a leading cause of bacterial pneumonia and sepsis.
- Sex-based differences in infectious disease susceptibility are increasingly recognized but not fully understood for pneumococcal infections.
Purpose of the Study:
- To investigate sex-based differences in susceptibility and immune response to Streptococcus pneumoniae infection in mice.
- To compare outcomes in models of invasive pneumonia and sepsis.
Main Methods:
- Male and female mice were infected with Streptococcus pneumoniae in pneumonia and sepsis models.
- Survival rates, weight loss, body temperature, bacterial load (colony-forming units), neutrophil recruitment, and proinflammatory cytokine levels were measured.
Main Results:
- Male mice exhibited significantly higher mortality rates, greater weight loss, and decreased body temperature compared to female mice.
- In pneumonia, female mice cleared lung infections, while males had higher bacterial loads and neutrophil recruitment in early stages.
- Male mice showed significantly increased levels of pro-inflammatory cytokines (T-helper 1-type responses) in both sepsis and pneumonia.
Conclusions:
- There are significant sex-based differences in susceptibility to Streptococcus pneumoniae infection.
- These differences are associated with variations in immune cell recruitment and inflammatory responses.
- Findings highlight the importance of considering sex as a biological variable in pneumococcal disease research and treatment.
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