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Effect of low extracellular pH on NF-κB activation in macrophages

Gerry, A. B. and Leake, D. S. (2014) Effect of low extracellular pH on NF-κB activation in macrophages. Atherosclerosis, 233 (2). pp. 537-544. ISSN 0021-9150

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To link to this item DOI: 10.1016/j.atherosclerosis.2014.01.014

Abstract/Summary

Objective: Many diseases, including atherosclerosis, involve chronic inflammation. The master transcription factor for inflammation is NF-κB. Inflammatory sites have a low extracellular pH. Our objective was to demonstrate the effect of pH on NF-κB activation and cytokine secretion. Methods: Mouse J774 macrophages or human THP-1 or monocyte-derived macrophages were incubated at pH 7.0–7.4 and inflammatory cytokine secretion and NF-κB activity were measured. Results: A pH of 7.0 greatly decreased pro-inflammatory cytokine secretion (TNF or IL-6) by J774 macrophages, but not THP-1 or human monocyte-derived macrophages. Upon stimulation of mouse macrophages, the levels of IκBα, which inhibits NF-κB, fell but low pH prevented its later increase, which normally restores the baseline activity of NF-κB, even though the levels of mRNA for IκBα were increased. pH 7.0 greatly increased and prolonged NF-κB binding to its consensus promoter sequence, especially the anti-inflammatory p50:p50 homodimers. Human p50 was overexpressed using adenovirus in THP-1 macrophages and monocyte-derived macrophages to see if it would confer pH sensitivity to NF-κB activity in human cells. Overexpression of p50 increased p50:p50 DNA-binding and in THP-1 macrophages inhibited considerably TNF and IL-6 secretion, but there was still no effect of pH on p50:p50 DNA binding or cytokine secretion. Conclusion: A modest decrease in pH can sometimes have marked effects on NF-κB activation and cytokine secretion and might be one reason to explain why mice normally develop less atherosclerosis than do humans.

Item Type:Article
Refereed:Yes
Divisions:Interdisciplinary centres and themes > Institute for Cardiovascular and Metabolic Research (ICMR)
Faculty of Life Sciences > School of Biological Sciences > Biomedical Sciences
ID Code:36330
Publisher:Elsevier

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