TNF-α Drives the CCL4 Expression in Human Monocytic Cells: Involvement of the SAPK/JNK and NF-κB Signaling Pathways.

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Abstract

Background/Aims: Increased circulatory levels of both TNF-α and CCL4/MIP-1β are found in metabolic diseases. However, it is unclear whether TNF-α which is a signature proinflammatory cytokine involved in metabolic inflammation, can induce/promote the expression of CCL4. Methods: THP-1 human monocytic cells and THP-1-derived macrophages were stimulated with TNF-α and LPS-treatment as a positive control. CCL4 mRNA/protein expression was measured using qRT-PCR/ELISA, respectively. Stress-activated protein kinases (SAPK)/ c-Jun N-terminal kinase (JNK) activity was determined using the assay kit. Mechanistic pathways were studied using anti-TNFR1/2 antibodies, pharmacological inhibitors, siRNAs, and NF-κB/AP-1 reporter-expressing THP-1-XBlue cells. Phosphorylation of signaling molecules was assessed by Western blotting. Results: TNF-α induces CCL4 expression at mRNA and protein levels, in both THP-1 monocytic cells and macrophages (P<0.05). TNF-α-driven CCL4 production was markedly abrogated by pre-treatment with anti-TNFR1/2 neutralizing antibodies. TNF-α treatment induced phosphorylation of SAPK/JNK, c-Jun, and NF-κB. Genetic and/or pharmacologic inhibition of SAPK/JNK and NF-κB pathways suppressed the TNF-α-induced CCL4 expression (P<0.05). NF-κB/AP-1 activity was found to be significantly increased in TNFα-treated SEAP reporter-expressing monocytic cells. Conclusion: These data suggest that TNF-α drives CCL4 expression in THP-1 monocytic cells/macrophages via the activation of SAPK/JNK and NF-κB pathways. The findings may provide new insights into understanding the regulatory role of TNF-α in augmenting CCL4 expression during inflammatory conditions.

Original languageEnglish
Pages (from-to)908-921
Number of pages14
JournalCellular Physiology and Biochemistry
Volume52
Issue number4
DOIs
Publication statusPublished - Apr 2019

Keywords

  • CCL4/MIP-1β
  • Inflammation
  • NF-κB
  • SAPK/JNK
  • THP-1
  • TNF-α

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