Post-transcriptional effects of extracellular pH on tumour necrosis factor-alpha production in RAW 246.7 and J774 A.1 cells.
The present studies determined the effects of extracellular pH (pH(o)) on the production of tumour necrosis factor-alpha (TNF-alpha) in the macrophage-like cell lines RAW 246.7 and J774 A.1. The cells were activated with lipopolysaccharide (LPS) at pH(o) 5.5, 6.5 or 7.4. TNF-alpha gene transcription was monitored by Northern blot analysis. Synthesis of the cytokine was monitored by ELISA measurements of the TNF-alpha content of cell-conditioned media (extracellularly released TNF-alpha) and cell lysates (cytosolic TNF-alpha). The magnitude of the TNF-alpha response differed markedly between the two cell lines. RAW cells were more responsive to LPS than were J774 cells. However, the effects of pH(o) on TNF-alpha production were similar in the two cell lines. TNF-alpha gene transcription was insensitive to experimental pH(o). The pH(o) had no effect on the abundance of TNF-alpha mRNA at 2, 4 or 18 h. Nonetheless, synthesis of TNF-alpha was affected significantly by pH(o). The TNF-alpha contents of cell-conditioned medium and cell lysate at 18 h were reduced progressively at lower pH(o) values. The data indicate that pH(o) alters TNF-alpha production in RAW and J774 cells at a post-transcriptional level. These findings suggest that pH(o) influences the phenotypic responses of macrophages to activating stimuli and modifies the role that macrophages play in inflammatory and immune actions.
Heming
T A
TA
Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-0876, USA. theming@utmb.edu
Tuazon
D M
DM
Davé
S K
SK
Chopra
A K
AK
Peterson
J W
JW
Bidani
A
A
D000704:Analysis of Variance; D000818:Animals; D015152:Blotting, Northern; D002470:Cell Survival; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005110:Extracellular Space / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha