Proteases, neutrophils, and periodontitis: the NET effect

Area of Science:

• Immunology
• Cellular Biology
• Infectious Disease

Background:

• Neutrophils are key immune cells, using antimicrobial substances and neutrophil extracellular traps (NETs) to combat pathogens.
• Serine proteases are vital for NET formation, and their absence in mice increases infection susceptibility.
• Papillon-Lefèvre syndrome is linked to mutations affecting serine proteases, impacting NET production.

Purpose of the Study:

• To investigate the role of serine proteases and NET formation in human neutrophil antimicrobial function.
• To assess the clinical relevance of NET deficiency in a patient with Papillon-Lefèvre syndrome.

Main Methods:

• Characterization of neutrophils from a patient with a dipeptidyl peptidase I gene mutation.
• In vitro assessment of pathogen killing by patient-derived neutrophils.
• Evaluation of the patient's susceptibility to bacterial infections.

Main Results:

• Neutrophils from the patient, lacking elastase and unable to form NETs, demonstrated effective in vitro pathogen killing.
• The patient showed no increased susceptibility to bacterial infections.
• These findings challenge the necessity of NETs for host protection against bacterial infections.

Conclusions:

• Human neutrophil proteases, essential for NET formation, are dispensable for protection against bacterial infections.
• The capacity for NET generation in vitro does not necessarily correlate with in vivo host defense effectiveness.