The complement membrane attack complex stimulates the prostanoid production of cultured glomerular epithelial cells

Area of Science:

• Nephrology
• Immunology
• Cell Biology

Background:

• Glomerular epithelial cells (GEC) play a critical role in maintaining kidney function.
• The complement system is a key component of the innate immune system.
• Dysregulation of complement activation is implicated in various glomerular diseases.

Purpose of the Study:

• To investigate the effect of terminal complement components on prostanoid release from cultured GEC.
• To elucidate the role of specific complement components (C5b-9) in modulating GEC metabolism.
• To explore the potential contribution of complement-mediated prostanoid production to glomerular injury.

Main Methods:

• Cultured rat GEC were incubated with purified complement components (C5b6, C7, C8, C9).
• Prostanoid release (prostaglandin E and thromboxane B2) was measured.
• Dose-dependency and time-course of prostanoid release were analyzed.
• The effect of cycloheximide on protein synthesis-dependent prostanoid release was assessed.

Main Results:

• Terminal complement components C5b6, C7, C8, and C9 significantly stimulated prostanoid release from GEC.
• The C5b-8 complex was also stimulatory, with C7 being essential for this effect.
• Prostanoid release exhibited a biphasic pattern, with early and late peaks.
• The late peak of prostaglandin E release was dependent on protein synthesis.

Conclusions:

• Terminal complement components activate glomerular epithelial cells to increase prostanoid production.
• These findings support the hypothesis that nonlytic complement deposition can alter GEC metabolism in vivo.
• Complement-induced prostanoid release may contribute to glomerular filter abnormalities observed in kidney diseases.