title: Effect of low extracellular pH on NF-κB activation in macrophages.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights, Reading, Berkshire RG6 6UB, United Kingdom. Electronic address: Andrew.Gerry@adaptimmune.com.
authors: A B
authors: AB
authors: Gerry
authors: Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights, Reading, Berkshire RG6 6UB, United Kingdom. Electronic address: d.s.leake@reading.ac.uk.
authors: D S
authors: DS
authors: Leake
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D004198:Disease Susceptibility; D045604:Extracellular Fluid / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D009000:Monocytes / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D020672:I-kappa B Proteins; C508600:IL6 protein, human; D015850:Interleukin-6; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; C577686:interleukin-6, mouse; D000072000:NF-KappaB Inhibitor alpha; D004247:DNA
keywords: Atherosclerosis; Cytokines; Inflammation; Low pH; Macrophages; NF-κB; p50 Homodimers