Post-transcriptional effects of extracellular pH on tumour necrosis factor-alpha production in RAW 246.7 and J774 A.1 cells

• Published in: Clinical science (1979) Vol. 100; no. 3; pp. 259 - 266
• Main Authors: Heming, T A, Tuazon, D M, Davé, S K, Chopra, A K, Peterson, J W, Bidani, A
• Format: Journal Article
• Language: English
• Published: England 01.03.2001
• Subjects: Analysis of Variance; Animals; Blotting, Northern; Cell Survival; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Extracellular Space - chemistry; Hydrogen-Ion Concentration; Lipopolysaccharides - pharmacology; Macrophages - metabolism; Mice; RNA, Messenger - analysis; Transcription, Genetic; Tumor Necrosis Factor-alpha - biosynthesis
• ISSN: 0143-5221
• DOI: 10.1042/CS20000192

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.