Phospholipase A2 is a circulating mediator in typhoid fever

Area of Science:

• Immunology
• Infectious Diseases
• Biochemistry

Background:

• Typhoid fever presents as a systemic disease with prolonged fever, yet specific proinflammatory mediators were previously unidentified.
• Extracellular phospholipase A2 (group II, 14-kDa), induced by cytokines like IL-1 and TNF, is a potential mediator of inflammatory effects.

Purpose of the Study:

• To investigate the role of circulating extracellular phospholipase A2 (PLA2) as a potential mediator in typhoid fever patients.
• To quantify PLA2 concentrations in typhoid fever patients during illness and recovery.

Main Methods:

• Measurement of circulating PLA2 concentrations in 12 typhoid fever patients upon admission and at various follow-up points, including after recovery.
• Assessment of PLA2 levels in relation to disease severity (complicated vs. uncomplicated).
• Investigation of PLA2 production in lipopolysaccharide-stimulated whole blood cultures.

Main Results:

• Mean PLA2 concentrations were significantly elevated in typhoid fever patients upon admission (1444 +/- 1560 ng/mL).
• PLA2 levels decreased significantly by day 14 of recovery (55 +/- 48 ng/mL).
• Patients with complicated typhoid fever exhibited higher PLA2 levels on admission compared to those with uncomplicated disease.
• PLA2 was not detected in lipopolysaccharide-stimulated whole blood cultures, suggesting extra-corporeal cellular origin.

Conclusions:

• Circulating extracellular phospholipase A2 (PLA2) is elevated in typhoid fever and may act as a mediator of the disease's inflammatory processes.
• The reduction in PLA2 levels post-treatment correlates with clinical improvement.
• PLA2 likely originates from non-blood cells, highlighting its systemic role in protracted inflammatory conditions like typhoid fever.