자 ᅦ online ML Comm DOI 10.3342/kjorl-hns.2008.51.12.1076 상피의 γδ T 세포 연세대학교의과대학이비인후과학교실, 기도점액연구소 김창훈 Epithelial γδ T cells Chang-Hoon Kim, MD, PhD Department of Otorhinolaryngology, The Airway Mucus Institute (TAMI), Yonsei University College of Medicine, Seoul, Korea 서론 T 세포는흉선 (thymus) 과말초림프조직 (peripheral lymphoid tissue) 을순환하는 αβ T-세포수용체 (T-cell receptor, TCR) 를발현하는대다수의 αβ T 세포와 γδ T- 세포수용체를발현하는소수의 γδ T 세포로구성된다. 1) 상피조직에상재하는 γδ T 세포는 (tissue-resi-dent γ δ T cells) 상당히다른양상을보여, 어느부위에서는 γ δ T 세포가대부분또는전부를차지하기도한다. 2) 이러한상피조직에상재하는 γδ T 세포는임프조직에존재하는 T 세포와는다른특징인제한적이거나 (limited) 일정한 (invariant) T-세포수용체발현양상을보인다. γδ T 세포는주로피부, 장, 혀, 식도, 기관, 폐, 생식기상피등에서발견된다. 이중피부상피조직내에상재하고있는 resident γδ T 세포 (dendritic epidermal T cells, DETC)(Fig. 1) 와장에상재하는 intestinal intraepithelial γδ T lymphocyte(iiel) 의역할에대하여가장많은연구가진행되었다. 3-5) γδ T 세포는흉선에서만들어져가장먼저다른부위로이동하는 T 세포로대부분피부, 장, 폐와생식기상피조직으로출생이전에이동한다. 6) γδ T 세포는 T-세포수용체의다양성을가지고있지는않지만상피조직에가해진여러가지의생물학적손상을인지하여반응하나, 이러한반응을유도하는자가항원에대해서는거의알려진것이없다. 활성화된 γδ T 세포는염증을조절하고, 세포의형질이변화한세포를파괴하며, 상처의치유를향상시키는것으로알려져있다. 6) 또한최근의연구결과에의하면 γδ T 세포는외부환경의자극에노출된조직의항상성 (homeostasis) 을유지, 복원하는조절자역할을한다고알려져있다. 1) 이에이논문에서는상피조직에상재하는 γδ T 세포의발생및역할에대한이해를기술하고자한다. 상피 γδ T 세포의기원 αβ T 세포와 γδ T 세포는흉선에존재하는같은전구세포 (precursor) 에서부터유래되었으며최근연구결과에따르면 αβ 또는 γδ TCR lineage 결정은 TCR 신호의강도에의해좌우된다고알려져있다. 7) 흉선에서만들어진 γδ T 전구세포는각지다른신체부위로이동하는데, 이중 invariant Vγ3Vδ1 TCR을사용하는 T 세포가가장먼저피부로이동한다. 8) 이세포를 dendritic epidermal T cells(detcs) 라고하고 dendritic process 를가지고각질세포 (keratinocyte) 와서로접촉한다. TCR δ chain 이없는형질전화생쥐의피부에서는 Vγ3Vδ1 T 세포대신 αβ T 세포가존재하지만손상된각질세포에반응하지않고그수가유지되지않는것을관찰할수있다. 9) 이러한결과는피부의항원을인식하는 γδ TCR의존재가 DETC의생존및유지에중요한역할을함을알려주는것이다. 상피 γδ T 세포의 Localization 흉선에서발생하는 T 세포의개체발생 (ontogeny) 의특징은순서가정해진재배열 (ordered rearrangement) 과특유 T-세포수용체유전자의발현이다. 여러연구자들에의하면 γ와 δ T-세포수용체유전자는 αβ T-세포수용체의유전자보다먼저재배열되고발현된다. 2,10) 특유 γδ T- 1076
김창훈 세포수용체는겹쳐지는파도모양 (overlapping waves) 으로발현된다. 결과적으로특유 γδ T 세포군은특징적인상피조직으로순차적으로이동하게되는것이다. 11,12) 개체발생의후기나출생이후에생성된 γδ T 세포는 αβ T 세포와같이혈액을돌거나말단림프기관에모이게된다. 이러한조직적인발생의패턴은조직특이적인 γδ T세포의확립에중요한역할을하는것으로알려져있다 (Fig. 2). γδ T 세포의기능 DETC는피부상피의 keratinocyte 와 contact하면서 keratinocyte growth factor(kgf), insulin-like growth factor-1(igf-1) 등을분비한다. IGF-1은 IGFR(+) DETC 의생존및 apoptosis 를조절하는것으로알려져있으며 KGF는손상된조직의복구과정에관여함으로서피부상피의선천면역에중요할역할을하고있다고알려져있다 (Fig. 3). 13,14) DETC는 IL-2, IL-3, GM-CSF, IFN-γ, TNF-α 등과같은 cytokine 과더불어 macrophage inflammatory protein-1α(mip-1α), MIP-1β, RANTES와같은 chemokine 을방출함으로서병원균의감염이나조직의손상에따른염증반응시상피조직내로면역세포가 infiltration되는과정을조절한다고보고되어있다. 15) 장에상재하는 intestinal intraepithelial γδ T lymphocyte(iiel) 는 C57BL6 생쥐의경우, 장에상재하고있는 iiel 의 50% 가 γδ TCR을가지는 γδ T 세포로알려져있다. iiel 은점막상피세포를보호하는역할을하는것으로알려져있으며, 이세포에이상이생길경우, 소화기점막의만성염증질환인 inflammatory bowel disease(ibd) 로발병됨이보고되어있다 (Fig. 4). 16) 그러나호흡기, 특히인체호흡기내에상재하고있는 resident γδ T 세포에대한연구는매우미흡한수준이며현재세계적으로진행되고있는연구역시하부호흡기인폐에만국한되어있다. 1988년 Charles Janeway에의해 γδ T 세포의 TCR 은 metabolically stressed epithelial 세포를인식하고제거하는기능을담당할것이라는가설이제안되었다. 17) 또 Wounded skin Fig. 1. Immunofluorescence staining of DETC on C57BL6 mouse skin. IGF-1 E14 SKIN Vγ3Vδ1 Invariant TCR BIRTH REPRODUCTIVE Vγ4Vδ1 Invariant TCR αβ T Cells Diverse TCRs INTESTINE Vγ5 pairs with Vδ5 Also Vδ4,6 or 7 Diverse sequences LYMPHOID Vγ2 pairs with Vδ5,6 or 7 Diverse junctional sequences LUNG Vγ2Vγ1 Iavariant in some strains Proliferation KGFs IGF-1R KGF KGFR Antigen IGF-1 Fig. 3. Tissue homeostasis and wound healing by KGF and IGF-1 secreted by DETC (Adapted from Immunological Review 2007; 215:114-22). Fig. 2. Expression of γδ-t cell antigen receptor (TCR) chains during murine fetal thymic development and subsequent localization of specific subsets in adult epithelial tissues. Individual TCR γ-chains are expressed in a series of overlapping waves in the fetal thymus (Garman nomenclature). Cells bearing specific TCR leave the thymus and migrate to specific epithelial sites in the mouse. They take up residence and persist in those locations. This results in a relatively tissue-specific expression of particular γδ-tcrs, which implies that epithelial γδ-t cells may recognize tissue-specific antigens. E 14, embryonic day 14 (Adapted from Am J Physiol Gastrointest Liver Physiol 2005;289:G627-30). Fig. 4. Immunofluorescence staining of iiel in intestine of C57BL6 mouse. 1077
상피의 γδ T 세포 한 IEL의표면에발현되는 TCR의 diversity 가제한적이라는사실에근거하여 γδ T 세포는 αβ T 세포와는다른물질에의해활성화될것이라제안되었다. 그러나 γδ T 세포를활성화시키는 TCR ligand 는현재까지잘알려지지않고있다. Mycobacterium bovis strain 에의한 intranasal infection시, resident Vγ2 T cell subset의 population 이증가하고, Vγ1 혹은 Vδ(+) T cell의 influx가증가한다고보고되어있으나, 18) 박테리아의어떤물질이 resident T 세포를활성화시키는지, 또는이과정에관여하는신호전달물질은무엇인지등에대한연구는전혀진행되고있지않다. Circulating T cell 혹은 injured epithelial 세포로부터방출되는다양한 inflamamtory cytokine 과 chemokine에의해 resident T 세포가활성화될것이라보고되어있으나자세한분자적기작은알려져있지않다 (Fig. 5). 19) 박테리아의감염시, 상피층에존재하는 resident γδ T 세포에의해방출되는 IL-17 를통하여감염부위로의중성구의 infiltration 이조절되며, 20) γδ T 세포 knock-out 생쥐감염모델에서 γδ T 세포는조직손상및생존률에중요한역할을하고있음이최근보고되었다. 21) 또한알레르기천식모델에서 γδ T 세포는 variable region 사용에따라서로다른역할을함이보고되었다. 22) 이러한일련의선행연구들은 resident γδ T 세포에의해호흡기점막면역체계가조절될것이라는예측을가능하게한다. 코점막상피에상재하는 γδ T 세포 Fig. 5. Fig. 1. Putative roles of resident and circulating γδ T cells in anticancer surveillance. γδ T cells are localized mainly in the epithelia, react with MICA and/or MICB and CD1+ tumor or antigen-presenting cells (APCs) and secrete interferon γ (IFNγ) and tumor necrosis factor α (TNF-α). By contrast, Vδ2 circulating T cells can recognize bacterial or endogenous phosphate antigens (P-Ags), and release IFN-γ, interleukin-4 (IL-4) and proinflammatory cytokines (e.g. TNF-α). The resident population of γδ T cells might interact with MICA- and/or MICBexpressing solid tumor cells through the natural-killercell receptor NKG2D and/or T-cell receptor (TCR), or recognize CD1-restricted molecules, whereas the circulating subset displays specificity for phosphate antigens expressed by hematological malignancies. CCR:CC-chemokine receptor, CXCR:CXC-chemokine receptor, MIP-1:macrophage inflammatory protein 1, N- CAM:neural-cell adhesion molecule, NKRP1A:natural-killercell receptor protein 1A, RANTES:regulated upon activation, normal T-cell expressed and secreted, TC:tumor cell (Adapted from Trends Immunol. 2002;23:14-8). 생쥐모델코점막의 γδ T 세포생쥐 (C57BL6 mouse) 코점막상피세포의기저막에가까이위치하고있는 resident γδ T 세포및 αβ T 세포를면역형광염색을통해국재화할수있었다 (Fig. 6A). 23) 코점막상피에상재하는 γδ T 세포는총 T 세포 (CD3+) 중약 20~30% 를차지하였고, 이는말초혈액에서 3% 미만인것에비해상당히많은숫자이다 (Fig. 6B). Resident nasal γδ T 세포는 CD4(-), CD8(-) 의 double negative 표현형을보였다 (Fig. 6C). Resident nasal γδ T 세포에서발현되는 TCR 의 variable gene usage를 RT-PCR(Fig. 7A) 과 FACS(Fig. 7B) 를이용하여분석하였다. 그결과 resident nasal γδ T 세포는 Vγ4/Vδ1 variable region gene을발현함을관찰하였다. 23) 이러한결과는 sorted cell 을가지고시행한 RT-PCR 에서확인되었다 (Fig. 7C). niel nlpl niel nlpl CD8α A B C Fig. 6. Characteristics of mouse nasal resident γδ T cells (Adapted from Journal of Leukocyte Biology 2008;84:1259-1263). CD3 CD4 1078
김창훈 Vδ 1 2 3 4 5 6 7 7-17 % cells % cells GL3 TCRβ only sort Vγ 2 3 4 5 Vδ 1 2 3 4 5 6 7 PAM A 3T3 B Fig. 7. Variable gene use of mouse resident nasal γδ T cells (Adapted from Journal of Leukocyte Biology 2008;84:1259-63). C Fig. 8. Immunofluorescent staining of γδ T cells in human normal nasal inferior turbinate mucosa (Adapted from Journal of Leu-kocyte Biology, 2008;84:1259-63). 인체코점막의 γδ T 세포 인체정상코점막상피세포점막상피및 lamina propria 에존재하는 nasal resident γδ T 세포의발현을면역형광염색법으로조사하여상피및 lamina propria 에상재하는인체코점막 γδ T 세포를발견할수있었다 (Fig. 8). 결 론 상피조직에상재하는 γδ T 세포는발생이나조직의국제및기능이말초임파조직에존재하는임파구와는상이하며, 상피손상의회복및항상성에중요한역할을하는것으로알려져있다. 아직잘알려져있지않은호흡기상피세포내에존재하는 γδ T 세포의특성및기능을이해할수있다면호흡기선천면역의연구에큰기여가될것으로기대한다. 본연구는연세대학교의과대학 2008 년도장기해외연수교수연구비 (6-2008-0089) 에의하여이루어졌습니다. REFERENCES 1) Jameson J, Havran WL. Skin gammadelta T-cell functions in homeostasis and wound healing. Immunol Rev 2007;215:114-22. 2) Allison JP, Havran WL. The immunobiology of T cells with invariant gamma delta antigen receptors. Annu Rev Immunol 1991;9:679-705. 3) Jameson JM, Sharp LL, Witherden DA, Havran WL. Regulation of skin cell homeostasis by gamma delta T cells. Front Biosci 2004;9: 2640-51. 4) Boismenu R, Havran WL. Modulation of epithelial cell growth by intraepithelial gamma delta T cells. Science 1994;266(5188):1253-5. 5) Boismenu R, Chen Y, Havran WL. The role of intraepithelial gammadelta T cells: A gut-feeling. Microbes Infect 1999;1(3):235-40. 6) Komori HK, Meehan TF, Havran WL. Epithelial and mucosal gamma delta T cells. Curr Opin Immunol 2006;18(5):534-8. 7) Pennington DJ, Silva-Santos B, Hayday AC. γδ T cell development-having the strength to get there. Curr Opin Immunol 2005;17 (2):108-15. 8) Garman RD, Doherty PJ, Raulet DH. Diversity, rearrangement, and expression of murine T cell g genes. Cell 1986;45(5):733-42. 9) Jameson JM, Cauvi G, Witherden DA, Havran WL. A keratinocyteresponsive γδ TCR is necessary for dendritic epidermal T cell activation by damaged keratinocytes and maintenance in the epidermis. J Immunol 2004;172(6):3573-9. 10) Hayday A, Tigelaar R. Immunoregulation in the tissues by γδ-t cells. Nat Rev Immunol 2003;3(3):233-42. 11) Havran WL, Allison JP. Origin of Thy-1 dendritic epidermal cells of adult mice from fetal thymic precursors. Nature 1990;344(6261): 68-70. 12) Itohara S, Farr AG, Lafaille JJ, Bonneville M, Takagaki Y, Haas W, et al. Homing of a γδ-thymocyte subset with homogenous T-cell receptors to mucosal epithelia. Nature 1990;343(6260):754-7. 13) Jameson J, Ugarte K, Chen N, Yachi P, Fuchs E, Boismenu R, et al. A role for skin gammadelta T cells in wound repair. Science 2002;296 (5568): 747-9. 14) Sharp LL, Jameson JM, Cauvi G, Havran WL. Dendritic epidermal T cells regulate skin homeostasis through local production of insulinlike growth factor 1. Nat Immunol 2005;6(1):73-9. 15) Havran WL, Chen Y, Boismenu R. Innate functions of epithelial gamma delta T cells. Adv Exp Med Biol 1998;452:29-35. 16) Chen Y, Chou K, Fuchs E, Havran WL, Boismenu R. Protection of the intestinal mucosa by intraepithelial gamma delta T cells. Proc Natl Acad Sci USA 2002;99(22):14338-43. 17) Janeway CA Jr, Jones B, Hayday A. Specificity and function of T cells bearing gamma delta receptors. Immunol Today 1988;9(3):73-6. 18) Dieli F, Ivanyi J, Marsh P, Williams A, Naylor I, Sireci G, et al. Characterization of lung gammadelta T cells following intranasal infection with Mycobacterium bovis bacillus Calmette-Guerin. J Immunol 2003;170(1):463-9. 19) Ferrarini M, Ferrero E, Dagna L, Poggi A, Zocchi MR. Human gammadelta T cells: A nonredundant system in the immune-surveillance against cancer. Trends Immunol 2002;23(1):14-8. 20) Shibata K, Yamada H, Hara H, Kishihara K, Yoshikai Y. Resident Vdelta1+ gammadelta T cells control early infiltration of neutrophils after Escherichia coli infection via IL-17 production. J Immunol 2007;178(7):4466-72. 21) Tschöp J, Martignoni A, Goetzman HS, Choi LG, Wang Q, Noel JG, et al. Gammadelta T cells mitigate the organ injury and mortality of sepsis. J Leukoc Biol 2008;83(3):581-8. 1079
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