Extracellular Release of CD11b by TLR9 Stimulation in Macrophages

• Published in: PloS one 2016-03, Vol.11 (3), p.e0150677-e0150677
• Main Authors: Kim, Dongbum, Kim, Te Ha, Wu, Guang, Park, Byoung Kwon, Ha, Ji-Hee, Kim, Yong-Sung, Lee, Keunwook, Lee, Younghee, Kwon, Hyung-Joo
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; Acidification; Activation; Analysis; Animals; Antigens; Backbone; Biology and Life Sciences; CD11b antigen; CD11b Antigen - metabolism; Cell culture; Cell Line; Cell surface; Chemokines; CpG islands; Cytokines; Dendritic cells; Deoxyribonucleic acid; DNA; Exosomes - metabolism; Extracellular Space - metabolism; Gene expression; Immunity; Immunomodulation; Inflammation; Innate immunity; Integrins; Kinases; Ligands; Lysosomes; Lysosomes - metabolism; Macrophages; Macrophages - drug effects; Macrophages - metabolism; MAP kinase; Medicine; Medicine and Health Sciences; Mice; NF-κB protein; Nucleotide sequence; Oligodeoxyribonucleotides - pharmacology; Oligonucleotides; p38 Mitogen-Activated Protein Kinases - antagonists & inhibitors; Phosphorothioate; Protein Kinase Inhibitors - pharmacology; Proteins; Research and Analysis Methods; Science; Stimulation; Surface markers; TLR9; TLR9 protein; Toll-Like Receptor 9 - agonists; Toll-Like Receptor 9 - metabolism; Toll-like receptors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0150677

CpG-DNA upregulates the expression of pro-inflammatory cytokines, chemokines and cell surface markers. Investigators have shown that CD11b (integrin αM) regulates TLR-triggered inflammatory responses in the macrophages and dendritic cells. Therefore, we aimed to identify the effects of CpG-DNA on the expression of CD11b in macrophages. There was no significant change in surface expression of CD11b after CpG-DNA stimulation. However, CD11b was released into culture supernatants after stimulation with phosphorothioate-backbone modified CpG-DNA such as PS-ODN CpG-DNA 1826(S). In contrast, MB-ODN 4531 and non-CpG-DNA control (regardless of backbone type and liposome-encapsulation) failed to induce release of CD11b. Therefore, the context of the CpG-DNA sequence and phosphorothioate backbone modification may regulate the effects of CpG-DNA on CD11b release. Based on inhibitor studies, CD11b release is mediated by p38 MAP kinase activation, but not by the PI3K and NF-κB activation. CD11b release is mediated by lysosomal degradation and by vacuolar acidification in response to CpG-DNA stimulation. The amount of CD11b in the exosome precipitant was significantly increased by CpG-DNA stimulation in vivo and in vitro depending on TLR9. Our observations perhaps give more insight into understanding of the mechanisms involved in CpG-DNA-induced immunomodulation in the innate immunity.