Increased expression of interleukin-1β in triglyceride-induced macrophage cell death is mediated by p38 MAP kinase

Triglyceride-induced macrophage cell death is triggered by caspase-1

Triglyceride (TG) induces macrophage cell death which contributes to the development of atherosclerosis. We confirmed that exogenous TG accumulates in human THP-1 macrophages and causes cell death. TG treated THP-1 macrophages exhibited no change in tumor necrosis factor (TNF)-α, interleukin (IL)-18, macrophage inflammatory protein (MIP)-1α, and IL-1R1 receptor mRNA expression. However, there was a marked decrease in IL-1β mRNA expression but an increase in IL-1β protein secretion. Decreased expression of IL-1β mRNA and increased secretion of IL-1β protein was not the direct cause of cell death. Until now, TG was assumed to induce necrotic cell death in macrophages. Since caspase-1 is known to be involved in activation and secretion of IL-1β protein and pyroptotic cell death, next we determined whether caspase-1 is associated with TG-induced macrophage cell death. We found an increase in caspase-1 activity in TG-treated THP-1 macrophages and inhibition of caspase-1 activity using a specific inhibitor partially rescued cell death. These results suggest activation of the pyroptotic pathway by TG. This is the first report implicating the activation of caspase-1 and the triggering of the pyroptosis pathway in TG-induced macrophage cell death.

Role of oxidative stress in infectious diseases. A review

Oxidative stress plays a dual role in infections. Free radicals protect against invading microorganisms, and they can also cause tissue damage during the resulting inflammation. In the process of infection, there is generation of reactive species by myeloperoxidase, NADPH oxidase, and nitric oxide synthase. On the other hand, reactive species can be generated among others, by cytochrome P450, some metals, and xanthine oxidase. Some pathologies arising during infection can be attributed to oxidative stress and generation of reactive species in infection can even have fatal consequences. This article reviews the basic pathways in which reactive species can accumulate during infectious diseases and discusses the related health consequences.