Complement activation in emergency department patients with severe sepsis

Area of Science:

• Immunology
• Critical Care Medicine
• Biochemistry

Background:

• Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection.
• Complement activation plays a critical role in sepsis pathophysiology.
• Understanding complement activation in community-acquired sepsis is crucial for developing targeted therapies.

Purpose of the Study:

• To assess the extent and mechanism of complement activation in community-acquired sepsis.
• To evaluate complement activation at emergency department presentation and after 24 hours of resuscitation.
• To investigate the correlation between complement activation and illness severity.

Main Methods:

• Prospective pilot study involving severe sepsis patients and healthy controls.
• Measurement of complement factors (Factor Bb, C4d, C3, C3a, C5a) at presentation and 24 hours.
• Quantitative resuscitation including antibiotics, MAP, and central venous oxygenation normalization.

Main Results:

• Septic patients exhibited significantly higher levels of all measured complement proteins compared to controls.
• Alternative pathway activation was prominent, indicated by elevated Factor Bb and C5a.
• No significant changes in complement mediator levels were observed after 24 hours of resuscitation.

Conclusions:

• Community-acquired sepsis is characterized by extensive complement activation, predominantly via the alternative pathway, at presentation.
• Current resuscitation strategies did not significantly impact complement activation markers within 24 hours.
• Further research is needed to explore therapeutic interventions targeting complement pathways in sepsis.