Cutting edge: critical role of intracellular osteopontin in antifungal innate immune responses.
We found that absence of osteopontin (OPN) in immunocompromised Rag2(-/-) mice, which lack T and B cells, made the mice extremely susceptible to an opportunistic fungus Pneumocystis, although immunocompetent OPN-deficient mice could clear Pneumocystis as well as wild-type mice. OPN has been studied as an extracellular protein, and the role of an intracellular isoform of OPN (iOPN) is still largely unknown. In this study, we elucidated the mechanism by which iOPN was involved in antifungal innate immunity. First, iOPN was essential for cluster formation of fungal receptors that detect Pneumocystis, including dectin-1, TLR2, and mannose receptor. Second, iOPN played a role as an adaptor molecule in TLR2 and dectin-1 signaling pathways and mediated ERK activation and cytokine production by zymosan, which simultaneously activates TLR2 and dectin-1 pathways. Third, iOPN enhanced phagocytosis and clearance of Pneumocystis. Our study suggests the critical involvement of iOPN in antifungal innate immunity.
Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
Makoto
M
Inoue
Yasuhiro
Y
Moriwaki
Tomohiro
T
Arikawa
Yu-Hsun
YH
Chen
Young Joo
YJ
Oh
Timothy
T
Oliver
Mari L
ML
Shinohara
D056704:Adaptive Immunity / Q000235:genetics; D000818:Animals; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D020022:Genetic Predisposition to Disease; D007113:Immunity, Innate / Q000235:genetics; D007424:Intracellular Fluid / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D037181:Lectins, C-Type; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000502:physiology; D053495:Osteopontin / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D011010:Pneumocystis / Q000254:growth & development* / Q000276:immunology*; D016720:Pneumocystis Infections / Q000276:immunology* / Q000382:microbiology* / Q000517:prevention & control; D051192:Receptors, Pattern Recognition / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000502:physiology; D000099181:Dectin-1
D037181:Lectins, C-Type; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D053495:Osteopontin; D051192:Receptors, Pattern Recognition; D051195:Toll-Like Receptor 2; D000099181:Dectin-1; C493486:Tlr2 protein, mouse