Autocrine regulation of interleukin-8 production in human monocytes

2000 ◽  
Vol 279 (6) ◽  
pp. L1129-L1136 ◽  
Author(s):  
Darren D. Browning ◽  
Wade C. Diehl ◽  
Matthew H. Hsu ◽  
Ingrid U. Schraufstatter ◽  
Richard D. Ye
Keyword(s):  
Mononuclear Cells ◽  
De Novo ◽  
Human Peripheral Blood ◽  
Surface Expression ◽  
Polymorphonuclear Neutrophils ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Expression ◽  
Peripheral Blood Mononuclear ◽  
Mitogen Activated Protein

Interleukin (IL)-8 is a C-X-C chemokine that plays an important role in acute inflammation through its G protein-coupled receptors CXCR1 and CXCR2. In this study, we investigated the role of IL-8 as an autocrine regulator of IL-8 production and the signaling mechanisms involved in human peripheral blood mononuclear cells (MNCs). Sepharose-immobilized IL-8 stimulated a sevenfold increase in IL-8 production within 2 h. IL-8 induced the expression of its own message, and IL-8 biosynthesis was inhibited by cycloheximide and actinomycin D, indicating de novo RNA and protein synthesis. In contrast to MNCs, polymorphonuclear neutrophils did not respond to the immobilized IL-8 with IL-8 production despite cell surface expression of CXCR1 and CXCR2. Melanoma growth-stimulatory activity/growth-related protein-α (MGSA/GROα), which binds CXCR2 but not CXCR1, was unable to either stimulate IL-8 secretion in MNCs or desensitize these cells to respond to immobilized IL-8. The involvement of mitogen-activated protein kinase (MAPK) in IL-8-induced IL-8 biosynthesis was suggested by the ability of PD-98059, an inhibitor of MAPK kinase, to block this function. Furthermore, IL-8 induced a significant increase in extracellular signal-regulated kinase 2 phosphorylation, whereas MGSA/GROα was much less effective. These findings support the role of IL-8 as an autocrine regulator of IL-8 production and suggest that this function is mediated by CXCR1 through activation of MAPK.

scholarly journals Tryptophanyl-tRNA Synthetase 1 Signals Activate TREM-1 via TLR2 and TLR4

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1283
Author(s):  
Tram T. T. Nguyen ◽  
Hee Kyeong Yoon ◽  
Yoon Tae Kim ◽  
Yun Hui Choi ◽  
Won-Kyu Lee ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Inflammatory Responses ◽  
Human Peripheral Blood ◽  
Surface Expression ◽  
Trna Synthetase ◽  
Cell Surface Expression ◽  
Peripheral Blood Mononuclear ◽  
Protein Levels ◽  
Syk Kinase ◽  
Inflammatory Processes

Tryptophanyl-tRNA synthetase 1 (WARS1) is an endogenous ligand of mammalian Toll-like receptors (TLR) 2 and TLR4. Microarray data, using mRNA from WARS1-treated human peripheral blood mononuclear cells (PBMCs), had indicated WARS1 to mainly activate innate inflammatory responses. However, exact molecular mechanism remains to be understood. The triggering receptor expressed on myeloid cells (TREM)-1 is an amplifier of pro-inflammatory processes. We found WARS1 to significantly activate TREM-1 at both mRNA and protein levels, along with its cell surface expression and secretion in macrophages. WARS1 stimulated TREM-1 production via TLR2 and TLR4, mediated by both MyD88 and TRIF, since targeted deletion of TLR4, TLR2, MyD88, and TRIF mostly abrogated TREM-1 activation. Furthermore, WARS1 promoted TREM-1 downstream phosphorylation of DAP12, Syk, and AKT. Knockdown of TREM-1 and inhibition of Syk kinase significantly suppressed the activation of inflammatory signaling loop from MyD88 and TRIF, leading to p38 MAPK, ERK, and NF-κB inactivation. Finally, MyD88, TRIF, and TREM-1 signaling pathways were shown to be cooperatively involved in WARS1-triggered massive production of IL-6, TNF-α, IFN-β, MIP-1α, MCP-1, and CXCL2, where activation of Syk kinase was crucial. Taken together, our data provided a new insight into WARS1′s strategy to amplify innate inflammatory responses via TREM-1.

Candida tropicalis induces pro-inflammatory cytokine production, NF-κB and MAPKs pathways regulation, and dectin-1 activation

2018 ◽  
Vol 64 (12) ◽  
pp. 937-944 ◽  
Author(s):  
Zhimin Duan ◽  
Qing Chen ◽  
Rong Zeng ◽  
Leilei Du ◽  
Caixia Liu ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Inflammatory Cytokine ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Mapk Signaling ◽  
Dependent Manner ◽  
Peripheral Blood Mononuclear ◽  
Downstream Signaling ◽  
Tnf Α ◽  
Mitogen Activated Protein

The prevalence of Candida infection induced by non-albicans Candida (NAC) species is increasing. However, as a common NAC species, C. tropicalis has received much less study in terms of host immunity than C. albicans has. In this study, we evaluated the pro-inflammatory cytokine responses evoked by C. tropicalis and determined whether dectin-1 and downstream NF-κB and mitogen-activated protein kinases (MAPKs) signaling pathways played roles in inflammation in human peripheral blood mononuclear cells (PBMCs) and THP-1 macrophage-like cells. Exposure of PBMCs and THP-1 macrophage-like cells to C. tropicalis led to the enhanced gene expression and secretion of TNF-α and IL-6 in a time- and dose-dependent manner. THP-1 macrophage-like cells being challenged by C. tropicalis resulted in the activation of the NF-κB, p38, and ERK1/2 MAPK signaling pathways. We also found that the expression of dectin-1 was increased with C. tropicalis treatment. These data reveal that dectin-1 may play a role in sensing the inflammation response induced by C. tropicalis and that NF-κB and MAPK are involved in the downstream signaling pathways in macrophages.

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