Suppression of leukotriene B4 and tumour necrosis factor α release in acute inflammatory responses by novel prenylated hydroquinone derivatives

Cellular acid–base status has been found to exert selective actions on the effector functions of activated macrophages (mϕ). We examined the effects of extracellular pH (pHo) on the production of tumour necrosis factor-α (TNF-α) induced by lipopolysaccharide (LPS) in resident alveolar mϕ. Cells were obtained by bronchoalveolar lavage of rabbits, activated in vitro with LPS, and cultured at pHo 5.5, 6.5 or 7.4 for up to 18 h. The relative abundance of TNF-α mRNA peaked at ~ 2 h. The peak transcript abundance was increased at lower pHo values. This finding probably reflected pre-transcription/transcription effects of pH, in as much as the stability of TNF-α mRNA induced with phorbol ester was unaffected by the experimental pHo values. TNF-α secretion by LPS-treated mϕ decreased at lower pHo values. The TNF-α content of mϕ-conditioned media decreased progressively with decrements in pHo. The reduced TNF-α secretion at pHo 5.5 was accompanied by an increase in the cytosolic TNF-α content (compared with that at pHo 7.4), indicating that pHo altered TNF-α secretion due, in part, to the intracellular retention of synthesized cytokine (i.e. a post-translation effect). The data show that pHo has multiple effects (pre-transcription/transcription and post-translation) on TNF-α production induced by LPS in resident alveolar mϕ. These results suggest that the role of alveolar mϕ in inflammatory responses is modulated by pHo, which may be important in tumours/abscesses and sites of infection where the external milieu is acidic.

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CD11bCD18-Dependent stimulation of leukotriene B4 synthesis by human neutrophils (PMN) is synergistically enhanced by tumour necrosis factor α and low dose diacylglycerol

The International Journal of Biochemistry & Cell Biology ◽

10.1016/1357-2725(96)00015-5 ◽

1996 ◽

Vol 28 (7) ◽

pp. 771-776 ◽

Cited By ~ 5

Author(s):

Robert Steadman ◽

Meryl M. Petersen ◽

John D. Williams

Keyword(s):

Tumour Necrosis Factor ◽

Tumour Necrosis ◽

Low Dose ◽

Leukotriene B4 ◽

Human Neutrophils ◽

Tumour Necrosis Factor Α ◽

Factor Α ◽

Necrosis Factor ◽

Stimulation Of

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Macrophages from IBD patients exhibit defective tumour necrosis factor-α secretion but otherwise normal or augmented pro-inflammatory responses to infection

Immunobiology ◽

10.1016/j.imbio.2011.01.002 ◽

2011 ◽

Vol 216 (8) ◽

pp. 961-970 ◽

Cited By ~ 28

Author(s):

Nair Campos ◽

Fernando Magro ◽

Ana Rita Castro ◽

Joana Cabral ◽

Pedro Rodrigues ◽

...

Keyword(s):

Tumour Necrosis Factor ◽

Tumour Necrosis ◽

Inflammatory Responses ◽

Tumour Necrosis Factor Α ◽

Factor Α ◽

Necrosis Factor

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Substrate specificity and inducibility of TACE (tumour necrosis factor α-converting enzyme) revisited: the Ala-Val preference, and induced intrinsic activity

Biochemical Society Symposium ◽

10.1042/bss0700039 ◽

2003 ◽

Vol 70 ◽

pp. 39-52 ◽

Cited By ~ 54

Author(s):

Roy A. Black ◽

John R. Doedens ◽

Rajeev Mahimkar ◽

Richard Johnson ◽

Lin Guo ◽

...

Keyword(s):

Substrate Specificity ◽

Recent Work ◽

Tumour Necrosis Factor ◽

Tumour Necrosis ◽

Transforming Growth Factor ◽

Intrinsic Activity ◽

Converting Enzyme ◽

Tumour Necrosis Factor Α ◽

Factor Α ◽

Necrosis Factor

Tumour necrosis factor α (TNFα)-converting enzyme (TACE/ADAM-17, where ADAM stands for a disintegrin and metalloproteinase) releases from the cell surface the extracellular domains of TNF and several other proteins. Previous studies have found that, while purified TACE preferentially cleaves peptides representing the processing sites in TNF and transforming growth factor α, the cellular enzyme nonetheless also sheds proteins with divergent cleavage sites very efficiently. More recent work, identifying the cleavage site in the p75 TNF receptor, quantifying the susceptibility of additional peptides to cleavage by TACE and identifying additional protein substrates, underlines the complexity of TACE-substrate interactions. In addition to substrate specificity, the mechanism underlying the increased rate of shedding caused by agents that activate cells remains poorly understood. Recent work in this area, utilizing a peptide substrate as a probe for cellular TACE activity, indicates that the intrinsic activity of the enzyme is somehow increased.

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