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Sci Rep. 2017 Apr 6;7:46165. doi: 10.1038/srep46165.

Phosphodiesterase 4B negatively regulates endotoxin-activated interleukin-1 receptor antagonist responses in macrophages.

Author information

1
Department of Life Sciences, National Central University, Zhongli District, Taoyuan City, Taiwan, Republic of China.
2
Internal Medicine, Landseed Hospital, Pingzhen District, Taoyuan City, Taiwan, Republic of China.
3
Graduate Institute of Immunology, National Taiwan University College of Medicine, Taipei, Taiwan, Republic of China.
4
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Francisco, California, USA.
5
Immunology Research Center, National Health Research Institutes, Miaoli, Taiwan, Republic of China.

Abstract

Activation of TLR4 by lipopolysaccharide (LPS) induces both pro-inflammatory and anti-inflammatory cytokine production in macrophages. Type 4 phosphodiesterases (PDE4) are key cAMP-hydrolyzing enzymes, and PDE4 inhibitors are considered as immunosuppressors to various inflammatory responses. We demonstrate here that PDE4 inhibitors enhance the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1Ra) secretion in LPS-activated mouse peritoneal macrophages, and this response was regulated at the transcriptional level rather than an increased IL-1Ra mRNA stability. Studies with PDE4-deficient macrophages revealed that the IL-1Ra upregulation elicited by LPS alone is PKA-independent, whereas the rolipram-enhanced response was mediated by inhibition of only PDE4B, one of the three PDE4 isoforms expressed in macrophages, and it requires PKA but not Epac activity. However, both pathways activate CREB to induce IL-1Ra expression. PDE4B ablation also promoted STAT3 phosphorylation (Tyr705) to LPS stimulation, but this STAT3 activation is not entirely responsible for the IL-1Ra upregulation in PDE4B-deficient macrophages. In a model of LPS-induced sepsis, only PDE4B-deficient mice displayed an increased circulating IL-1Ra, suggesting a protective role of PDE4B inactivation in vivo. These findings demonstrate that PDE4B negatively modulates anti-inflammatory cytokine expression in innate immune cells, and selectively targeting PDE4B should retain the therapeutic benefits of nonselective PDE4 inhibitors.

PMID:
28383060
PMCID:
PMC5382768
DOI:
10.1038/srep46165
[Indexed for MEDLINE]
Free PMC Article

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