The Effect of Hypoxia on the Production of Interleukin-10 (IL-10) In Human Mononuclear Cells
thesisposted on 2012-03-21, 14:23 authored by Allen Ping-Lun Wang
Macrophages play an important role in both innate and adaptive immunity by engulfing intruding pathogens and damaged or infected cells, antigen presentation, and by secretion of immune mediators. Interleukin 10 (IL-10) is a potent anti-inflammatory cytokine mainly produced by macrophages in response to cell activation, which serves to suppress immune reactions and inflammation. Hypoxia refers to oxygen deprivation. It is a common condition found in pathological tissues. The relationship between hypoxia and the production of IL-10 by macrophage is not yet thoroughly understood. In previous unpublished work by Staples and Burke et. al., it was found that both basal and LPS-induced IL-10 mRNA and protein are reduced in hypoxia. In the present study, it was shown that the transcription factor Hypoxia Inducible Factor 1 (HIF-1) appears to be involved in this reduction of IL-10 production in hypoxia. Although the regulatory elements on the IL-10 promoter responsible for this blockage effect were not definitively identified, our results indicated that the activity of a -4kb IL-10 luciferase reporter adenovirus was significantly reduced in cells treated with the HIF-1 inducing agents, cobalt chloride and desferrioxamine. The activity of a -195bp IL-10 luciferase reporter adenovirus was also decreased in the HIF-1inducing agent treated samples. These data imply that either by indirect interaction or physically binding to the IL-10 promoter or gene, HIF-1 does play a role in blocking IL-10 expression in hypoxia. Sequence and transcription factor analysis indicated the presence of a HIF-1 consensus sequence hypoxia responsive element (HRE) located in the -2,171bp to -2,187bp position on the IL-10 promoter. This result suggests that HIF-1 may affect IL-10 production, at least in part, by physically binding to its promoter. Lastly, we showed that the effect of hypoxia on IL-10 expression is observed with a range of different toll-like receptor ligands, and is not limited to induction by LPS.
Date of award2010-07-07
Awarding institutionUniversity of Leicester