Interaction between Mitochondrial Reactive Oxygen Species, Heme Oxygenase, and Nitric Oxide Synthase Stimulates Phagocytosis in Macrophages

Abstract

BackgroundMacrophages are cells of the innate immune system that populate every organ. They are required not only for defense against invading pathogens and tissue repair but also for maintenance of tissue homeostasis and iron homeostasis.AimThe aim of this study is to understand whether heme oxygenase (HO) and nitric oxide synthase (NOS) contribute to the regulation of nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity and phagocytosis, two key components of macrophage function.MethodsThis study was carried out using resting J774A.1 macrophages treated with hemin or vehicle. Activity of NOS, HO, or NOX was inhibited using specific inhibitors. Reactive oxygen species (ROS) formation was determined by Amplex® red assay, and phagocytosis was measured using fluorescein isothiocyanate-labeled bacteria. In addition, we analyzed the fate of the intracellular heme by using electron spin resonance.ResultsWe show that both enzymes NOS and HO are essential for phagocytic activity of macrophages. NOS does not directly affect phagocytosis, but stimulates NOX activity via nitric oxide-triggered ROS production of mitochondria. Treatment of macrophages with hemin results in intracellular accumulation of ferrous heme and an inhibition of phagocytosis. In contrast to NOS, HO products, including carbon monoxide, neither clearly affect NOX activity nor clearly affect phagocytosis, but phagocytosis is accelerated by HO-mediated degradation of heme.ConclusionBoth enzymes contribute to the bactericidal activity of macrophages independently, by controlling different pathways.

Immunomodulatory Effects of N-Acetyl Chitooligosaccharides on RAW264.7 Macrophages

“…During the process of macrophage activation, NO production is usually accompanied by ROS production and the secretion of pro-inflammatory cytokines [42]. In the present study, unlike LPS and COS, none of the eight NACOS samples were able to enhance NO production, and HNACOS, NACOS1, and NACOS6 significantly downregulated both iNOS gene expression and NO production.…”

Transcriptomic Profiles of Monocyte-Derived Macrophages in Response to Escherichia coli is Associated with the Host Genetics

“…During inflammation, MDMs play a crucial role in eliminating the pathogens, attracting cells of the adaptive immune system to the tissue, and re-stimulating the lymphocytes as they enter into the inflamed tissues 14 . Phagocytosis and production of Reactive Oxygen and Nitrogen Species (ROS and RNS) via the oxidative burst process are the main microbicidal functions of macrophages 15 . Nitric oxide (NO − ) is a member of the RNS produced by macrophages with strong bactericidal activity 16 .…”

Single or Combined Dietary Supply of Psidium guajava and Phyllanthus amarus Extracts Differentially Modulate Immune Responses and Liver Proteome in Striped Catfish (Pangasianodon hyphophthalmus)

“…Similarly, the leaf of P. guajava and mango Mangifera indica extract-based diets also significantly enhanced RBA production in rohu after a 35-day feeding period (9). As mentioned above, ROS are generated by neutrophils and macrophages during bacterial infection, while NOS is created as a signaling molecule in ROS generation during phagocytosis (43). Enhanced activities of ROS and NOS are seen as indicators of immune condition.…”