Mechanism of IL-1α expression, maturation and secretion in macrophages infected with Corynebacterium pseudotuberculosis

Abstract:

[Objective] Corynebacterium pseudotuberculosis(Cp) infection of animals often causes visceral and superficial lymph node abscesses,which is characterized by a large increase in inflammatory cytokines at the infected site. This study aimed to investigate the effect of Corynebacterium pseudotuberculosis(Cp) infection on IL-1α maturation and secretion in macrophages and the underlying mechanism.[Methods]The IL-1α expression,maturation and secretion in macrophages infected with Cp (ATCC19410,XH02) and phospholipase D gene (pld) deficient strains (ATCC19410Δpld,XH02Δpld) were evaluated by real-time quantitative PCR,ELISA and Western blotting.Further,the effects of Ca²⁺ chelates (EDTA,EGTA+Mg²⁺ and BAPTA-AM) and calpain inhibitors (calpain inhibitor Ⅲ,calpain inhibitor Ⅳ and EST) on IL-1α maturation and secretion in macrophages infected with Cp were tested.[Results] Cp infection induced increasing of IL-1α mRNA expression and secretion in macrophages,and the IL-1α mRNA expression and secretion in ATCC19410Δpld-infected and XH02Δpld-infected macrophages were significantly decreased compared with those of ATCC19410-infected and XH02-infected macrophages.The intracellular Ca²⁺ concentration and calpain activity were elevated in macrophages after Cp infection,while they were lowered in those infected with pld deficient Cp.Treatment of EDTA,EGTA+Mg²⁺,BAPTA-AM,calpain inhibitor Ⅲ and calpain inhibitor Ⅳ resulted in remarkable decrease of IL-1α expression and secretion in Cp infected macrophages.[Conclusion] Cp infection induced the IL-1α expression,maturation and secretion in macrophages,and phospholipase D was involved in this process.The IL-1α maturation and secretion in macrophages mediated by Cp were related to the increase of intracellular Ca²⁺and the activation of calpain.

Key words:Corynebacterium pseudotuberculosis;macrophages;IL-1α;phospholipase D;calpain