13:40 - 15:10
Room: ANA Crowne Plaza “Ohtori” Room A
Workshop Session
Chair/s:
Mitsutoshi Yoneyama, Shinobu Saijo
Two distinct ITAM-coupled receptors recognize mycobacterial mycolic acid-containing lipids and differently regulate immune responses.
Ei'ichi Iizasa1, Takayuki Uematsu2, Yasushi Chuma3, Hideyasu Kiyohara3, Mio Kutobta4, Masayuki Umemura5, Goro Matsuzaki5, Sho Yamasaki6, Hiromitsu Hara1
1Department of Immunology, Division of Infection and Immunity, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan, 2Research and Development Department, Japan BCG Laboratory, Tokyo, Japan, 3Division of Biomedical Laboratory, Department of Biomedical Research Kitasato University Medical Center, Saitama, Japan, 4Department of Biomolecular Sciences, Faculty of Medicine, Saga University, Saga, Japan, 5Tropical Biosphere Research Center University of the Ryukyus, Naha, Japan, 6Department of Molecular Immunology, Division of Host Defense, Research Institute for Microbial Disease, Osaka University,, Osaka, Japan

Mycobacterium tuberculosis remains an important cause of morbidity and mortality worldwide. Macrophages (Mφs) represent first line to defense against pathgens. Pattern recognition receptors (PRRs) expressed on Mφs detect pathogen-associated molecular patterns (PAMPs) of pathogens to activate immune responses. Recent reports have highlighted the importance of ITAM-coupled receptors (ITAMRs) including C-type lectin receptors in the recognition of PAMPs to regulate immune responses. Mycobacteria paradoxically live in macrophages. Thus the regulation of immune responses are important for mycobacterial infection. In this study, we found that one of ITAMRs TREM2 directly recognized mycobacterial PAMPs, mycolic acid (MA) and MA-containing lipids. Its recognition of non-glycosylated MAs, such MA itself and glycerol monomycolate (GroMM), induced the production of MCP-1 but not TNF-α and any other inflammatory cytokines, as far as we examined. In contrast, Mincle, which is the receptor for Torehalose-di-mycolate (TDM), also recognized another glycosylated MA, GMM but not non-glycosylated MAs. Mincle recognition of these glycosylated MAs induced the production of various cytokines including MCP-1 and TNF-α. The glycosylated but not non-glycosylated MAs also induced nitric oxide (NO) production. Interestingly, TREM2 is found to also ecognize these glycosylated MAs and inhibited these cytokine and NO productions. BCG infection of Trem2--deficient mice accelerated clearance of bacteria comparing to that of WT. These results shows the glycosylated MAs and non-glycosylated MAs differently regulate host immune responses through Mincle and TREM2. Although Mincle recruits macrophages for killing bacteria, TREM2 harness the host immunity to produce only MCP-1 to recruit macrophages lacking bactericidal activity for their propagation.


Reference:
Mo-WS1-3
Session:
Workshop 1, ‟Innate immunity and infection”
Presenter/s:
Ei'ichi Iizasa
Presentation type:
Oral Presentation
Room:
ANA Crowne Plaza “Ohtori” Room A
Chair/s:
Mitsutoshi Yoneyama, Shinobu Saijo
Date:
Monday, 30 October 2017
Time:
14:00 - 14:10
Session times:
13:40 - 15:10