The TLR-2/TLR-6 agonist macrophage-activating lipopeptide-2 augments human NK cell cytotoxicity when PGE2 production by monocytes is inhibited by a COX-2 blocker.

Abstract

Macrophage-activating lipopeptide-2 (MALP-2) is a potent inducer of proinflammatory cytokine secretion by macrophages, monocytes, and dendritic cells. MALP-2 was reported to be involved in natural killer (NK) cell activation and ensuing tumor rejection. However, the mechanism of MALP-2-mediated NK cell activation remained unclear. Therefore, we studied the effects of MALP-2 on cultured human NK cells. We found that MALP-2 had no direct effect on NK cells. Instead, MALP-2 acted on monocytes and triggered the release of different molecules such as interleukin (IL)-1β, IL-6, IL-10, IL-12, IL-15, interferon gamma-induced protein (IP-10), and prostaglandin (PG)-E2. Our data show that monocyte-derived IP-10 could significantly induce NK cell cytotoxicity as long as the immunosuppression by PGE2 is specifically inhibited by cyclooxygenase (COX)-2 blockade. In summary, our results show that MALP-2-mediated stimulation of monocytes results in the production of several mediators which, depending on the prevailing conditions, affect the activity of NK cells in various ways. Hence, MALP-2 administration with concurrent blocking of COX-2 can be considered as a promising approach in MALP-2-based adjuvant tumor therapies.

• Authors: Christina Müller, Dejene M Tufa, Debanjana Chatterjee, Peter F Mühlradt, Reinhold E Schmidt, Roland Jacobs
• Journal: Cancer immunology, immunotherapy : CII (Cancer Immunol Immunother) Vol. 64 Issue 9 Pg. 1175-84 (Sep 2015) ISSN: 1432-0851 [Electronic] Germany
• PMID: 26036909 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cyclooxygenase 2 Inhibitors
• Lipopeptides
• TLR2 protein, human
• TLR6 protein, human
• Toll-Like Receptor 2
• Toll-Like Receptor 6
• macrophage stimulatory lipopeptide 2
• Dinoprostone

Topics

• Cells, Cultured
• Cyclooxygenase 2 Inhibitors (immunology, pharmacology)
• Dinoprostone (antagonists & inhibitors, biosynthesis, immunology)
• Humans
• Killer Cells, Natural (drug effects, immunology)
• Lipopeptides (immunology, pharmacology)
• Monocytes (drug effects, immunology)
• Signal Transduction
• Toll-Like Receptor 2 (agonists)
• Toll-Like Receptor 6 (agonists)