title: Intracellular NAD+ levels are associated with LPS-induced TNF-α release in pro-inflammatory macrophages.
abstract: Metabolism and immune responses have been shown to be closely linked and as our understanding increases, so do the intricacies of the level of linkage. NAD(+) has previously been shown to regulate tumour necrosis factor-α (TNF-α) synthesis and TNF-α has been shown to regulate NAD(+) homoeostasis providing a link between a pro-inflammatory response and redox status. In the present study, we have used THP-1 differentiation into pro- (M1-like) and anti- (M2-like) inflammatory macrophage subset models to investigate this link further. Pro- and anti-inflammatory macrophages showed different resting NAD(+) levels and expression levels of NAD(+) homoeostasis enzymes. Challenge with bacterial lipopolysaccharide, a pro-inflammatory stimulus for macrophages, caused a large, biphasic and transient increase in NAD(+) levels in pro- but not anti-inflammatory macrophages that were correlated with TNF-α release and inhibition of certain NAD(+) synthesis pathways blocked TNF-α release. Lipopolysaccharide stimulation also caused changes in mRNA levels of some NAD(+) homoeostasis enzymes in M1-like cells. Surprisingly, despite M2-like cells not releasing TNF-α or changing NAD(+) levels in response to lipopolysaccharide, they showed similar mRNA changes compared with M1-like cells. These data further strengthen the link between pro-inflammatory responses in macrophages and NAD(+). The agonist-induced rise in NAD(+) shows striking parallels to well-known second messengers and raises the possibility that NAD(+) is acting in a similar manner in this model.
authors.affiliation: School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, U.K.
authors.forename: Abbas Jawad
authors.initials: AJ
authors.lastname: Al-Shabany
authors.affiliation: School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, U.K.
authors.forename: Alan John
authors.initials: AJ
authors.lastname: Moody
authors.affiliation: School of Biomedical and Healthcare Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, U.K.
authors.forename: Andrew David
authors.initials: AD
authors.lastname: Foey
authors.affiliation: School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, U.K. richard.billington@plymouth.ac.uk.
authors.forename: Richard Andrew
authors.initials: RA
authors.lastname: Billington
mesh_terms: D045744:Cell Line, Tumor; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D008070:Lipopolysaccharides / Q000633:toxicity*; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D009243:NAD / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009243:NAD
keywords: TNF-α; immune responses; lipopolysaccharide (LPS); macrophages; pyridine nucleotides; second messenger