The chronic consequences of severe sepsis

Area of Science:

• Immunology
• Critical Care Medicine
• Pathology

Background:

• Severe sepsis causes significant short-term mortality and long-term morbidity.
• Survivors of severe sepsis experience high mortality rates within a year, often due to lung complications.
• The cellular and molecular mechanisms driving long-term sepsis sequelae and lung injury require further investigation.

Purpose of the Study:

• To investigate the long-term consequences of severe sepsis on lung immunity.
• To understand the mechanisms underlying increased susceptibility to secondary infections post-sepsis.
• To identify specific immune alterations in the lungs of sepsis survivors.

Main Methods:

• Utilized a murine model of experimental sepsis induced by cecal ligation and puncture (CLP).
• Assessed the survival rates of sepsis survivors when challenged with a secondary fungal infection at different time points post-CLP.
• Analyzed changes in cytokine expression, Toll-like receptor expression, and lung leukocyte populations in surviving mice.

Main Results:

• Sepsis survivors (60% survival rate post-CLP) exhibited 100% mortality when challenged with fungal infection 3 and 15 days after recovery.
• Increased mortality correlated with altered cytokine profiles and Toll-like receptor expression.
• Significant changes in lung leukocyte populations were observed in sepsis survivors.

Conclusions:

• The lungs of severe sepsis survivors remain susceptible to secondary infections for extended periods.
• Mechanisms include altered inflammatory cytokine and chemokine profiles (e.g., MCP-1, C10), potentially affecting innate immune cells like dendritic cells and macrophages.
• These alterations may contribute to the immunosuppression observed after sepsis, predisposing patients to nosocomial infections.