Burkholderia cenocepacia induces neutrophil necrosis in chronic granulomatous disease

Area of Science:

• Immunology
• Microbiology
• Pathogenesis

Background:

• The Burkholderia cepacia complex poses a severe threat to patients with chronic granulomatous disease (CGD).
• CGD patients have phagocytes that cannot produce reactive oxygen species (ROS), impairing their ability to fight infections.
• B. cepacia complex is exceptionally virulent in CGD, leading to septicemia and high mortality rates.

Purpose of the Study:

• To investigate the interaction between Burkholderia cenocepacia and human neutrophils, particularly in the context of CGD.
• To elucidate the mechanisms underlying the heightened virulence of B. cepacia complex in CGD patients.

Main Methods:

• Phagocytosis assays using normal human neutrophils and neutrophils from CGD patients.
• Assessment of neutrophil apoptosis and necrosis following bacterial challenge.
• Investigation of the role of ROS and bacterial viability in the observed cellular responses.

Main Results:

• B. cenocepacia was readily ingested by normal neutrophils, inducing apoptosis independent of ROS.
• Neutrophils from CGD patients underwent apoptosis to a similar extent as normal neutrophils.
• Crucially, B. cenocepacia induced necrosis in CGD neutrophils, but not in normal neutrophils.

Conclusions:

• The pro-necrotic effect of B. cenocepacia on CGD neutrophils, occurring in the absence of ROS, may be responsible for its extreme virulence in these patients.
• Bacterial viability is essential for the pro-apoptotic and pro-necrotic effects.
• Understanding these mechanisms could inform therapeutic strategies for CGD patients infected with B. cepacia complex.