19:10 - 21:00
Room: Ishikawa Ongakudō Interchange Hall
Poster Session
Molecular mechanism of anti-pneumococcal immune responses by Dectin-1
Yukiko Akahori1, 2, Rikio Yabe2, Yoichiro Iwakura3, Shinobu Saijo2
1International University of Health and Welfare, Narita, Japan, 2Medical Mycology Research Center, Chiba University, Chiba, Japan, 3Center for Experimental Animal Models, Institute for Biomedical Sciences, Tokyo University of Science, Noda, Japan

Streptococcus pneumoniae is the major prevalent pathogen causing community-acquired pneumonia and other invasive diseases like meningitis and sepsis. An event of anti-pneumococcal immune responses is orchestrated by a panel of pattern recognition receptors by innate immune cells, such as Toll-like receptors (TLRs) and C-type lectin receptors (CLRs). Dendritic cell (DC)-associated C-type lectin-2 (Dectin-2), a member of the CLR family, is highly expressed in innate immune cells including DCs, macrophages and neutrophils. Dectin-2 recognizes mannose-containing glycoconjugates through its extracellular carbohydrate-recognition domain. Upon ligand-binding, Dectin-2 induces activation of immune responses, including inflammatory cytokine production through the association of ITAM-containing Fc receptor γ chain (FcRγ). We have recently reported that Dectin-2 recognizes mannose-containing capsule components from S. pneumoniae, promotes inflammatory cytokine production and plays a critical role in host defense against S. pneumoniae infection. On the other hand, the importance of Dectin-1, a β-glucan-binding CLR that is expressed in innate immune cells, in control of S. pneumoniae infection remains to be elusive. In this study, we found that Dectin-1 gene expression was increased in the lung of S. pneumoniae-infected mice. Dectin-1-positive cells were infiltrated in the lung from the mice. Dectin-1-Fc, a soluble form of Dectin-1 fused with an IgG Fc domain, bound to several S. pneumoniae strains. The binding was cancelled by β-glucanase treatment. Following stimulation with S. pneumoniae, Dectin-1-overexpressing RAW264.7 cells showed enhanced inflammatory cytokine production compared with parent RAW264.7 cells. Bone marrow-derived dendritic cells (BMDCs) from Dectin-1-deficient mice resulted in impaired inflammatory cytokine production relative to wild type BMDCs. Taken together, these data suggest Dectin-1 plays an important role in innate immune responses to S. pneumoniae infection in the lung.


Reference:
Tu-P6-23
Session:
Poster Session 6 “Cytokines in mucosal immunity”
Presenter/s:
Yukiko Akahori
Presentation type:
Poster Presentation
Room:
Ishikawa Ongakudō Interchange Hall
Date:
Tuesday, 31 October 2017
Time:
19:10 - 21:00
Session times:
19:10 - 21:00