Nguyên nhân gây lão hóa được giải thích bằng nhiều thuyết khác nhau: thuyết di truyền, thuyết gốc tự do,. Ngoài ra, hiện tượng lão hóa có liên quan đến đột biến gen còn gây hội chứng già trước tuổi hay liên quan đến tuổi thọ con người. | 348 ELUCIDATING INFLAMMATORY MEDIATORS OF DISEASE Table Regulatory T-cell Populations Cell Type Generation Location Markers Properties and Function References Natural Tregs Generated in the CD4 CD25 Foxp3 Antigen specific secrete IL-10 Hsieh et al. 2004 Fontenot thymus predominantly CD45RBlow CD62L and or TGF-p suppressive Rudensky 2005 Ziegler 2006 located in lymphoid org ans migrate toward sites of inflammation CTLA-4 or CD152 GITR CD127 CD38 activity inhibit effector T-cell functions contact dependent require CD80 and CD86 ligands on target T cells Scalzo et al. 2006 Inducible or Generated in the CD4 CD25 Target APC and T cells Groux et al. 1997 Graca adaptive Tregs periphery migrate CD45RO prevent autoimmune colitis et al. 2002 Chen et al. 2003 1 Tr1 toward sites of and inflammation of the Apostolou et al. 2004 Cottrez 2 Th3 inflammation digestive track mainly the gut and are mainly involved in oral tolerance Groux 2004 Tr1 From naive CD4 T cells in the presence of IL-10 and IFN-a Secrete mainly IL-10 but also TGF-p IL-5 and IFN-y do not secrete IL-2 or IL-4 inhibit Th1 and Th2 cell responses regulate both naive and memory T cells inhibit T-cell-mediated responses to pathogens and alloantigens and cancer target APC Groux et al. 1997 Foussat et al. 2003 Roncarolo et al. 2003 Scalzo et al. 2006 Th3 Through oral antigen administration Produce mainly TGF- P but also IL-10 suppress APC and T-cells mainly Th2 Weiner 1997 Scalzo et al. 2006 T helper 1 cells Generated in the CD4 CD25 Produce IL-2 IFN-y Mosmann Coffman 1989 Boom Th1 periphery from Th0 or Th2 cells mainly in the presence of IL-12 STAT-4 T-bet lymphotoxin-a target Th2 cells activate phagocytosis opsonization and complement protection against intracellular antigens responsible for autoimmunity and inflammation et al. 1990 Le Gros et al. 1990 Romagnani 1991 1994 1997 Hsieh et al. 1993 T helper 2 cells Generated in the CD4 CD25 Secrete IL-4 IL-5 IL-9 IL-13 Abbas et al. 1996 Annunziato Th2 periphery from
