Heme and hemolysis in innate immunity: adding insult to injury. (February 2018)

• Record Type: Journal Article
• Authors: Martins, Rui; Knapp, Sylvia
• Is Part Of: Current opinion in immunology. Volume 50(2018)
• Page Start: 14
• Page End: 20
• Publication Date: 2018-02
• Subjects: Immunology -- Periodicals; Allergy -- Periodicals; Immunology -- Abstracts -- Periodicals; Allergy -- Abstracts -- Periodicals; 616.079
• DOI: 10.1016/j.coi.2017.10.005
• Languages: English
• ISSNs: 0952-7915

Abstract

Highlights: Severe hemolytic disorders pose a serious risk for bacterial infections. Hemolysis is associated with the release of its heme moiety. Heme drives hemolysis-associated pathology due to its pro-oxidant, pro-inflammatory and immunomodulatory properties. Excess labile heme inhibits bacterial phagocytosis and chemotaxis, ultimately impairing host defense against bacterial sepsis. Abstract : Heme is a vital, iron-containing prosthetic molecule present in a variety of proteins, of which hemoglobin is the most abundant. While the reactivity afforded by its central iron ion is essential for many cellular processes, it renders heme a potentially damaging molecule upon its release from hemeproteins, as it can catalyze the generation of reactive oxygen species. Severe intravascular hemolysis results in the leakage of vast amounts of hemoglobin, and subsequently, heme into the plasma. As such, heme is increasingly recognized as a major driving force for hemolysis-associated pathology including an increased risk for bacterial infections, due to its pro-oxidant, cytotoxic and immunomodulatory effects. Here, we provide a succinct review of recent, significant developments on how heme can influence innate immune functions, ranging from the maintenance of iron homeostasis by macrophages, the modulation of inflammatory responses, to its role in altering resistance mechanisms against bacterial infections.