Intestinal fibroblast-derived IL-10 increases survival of mucosal T cells by inhibiting growth factor deprivation- and Fas-mediated apoptosis.
Mucosal T cells are essential to immune tolerance in the intestine, an organ constantly exposed to large amounts of dietary and bacterial Ags. We investigated whether local fibroblasts affect mucosal T cell survival, which is critical for maintenance of immune tolerance. Coculture with autologous fibroblasts significantly increased viability of mucosal T cells by inhibiting IL-2 deprivation- and Fas-mediated apoptosis, an effect that was both contact- and secreted product-dependent. Investigation of anti-apoptotic factors in the fibroblast-conditioned medium (FCM) revealed the presence of IL-10 and PGE2, but not IFN-beta, IL-2, or IL-15. Although recombinant IFN-beta, but not PGE2, effectively prevented T cell apoptosis, neutralizing Ab studies showed that only IL-10 blockade significantly increased T cells apoptosis, whereas neutralizing IFN-beta or IFN-alpha failed to inhibit the anti-apoptotic effect of FCM. To confirm that fibroblast-derived IL-10 was responsible for preserving mucosal T cell viability, IL-10 mRNA was demonstrated in fibroblasts by Southern blotting and RT-PCR. When FCM was submitted to HPLC fractionation, only the peak matching rIL-10 contained the anti-apoptotic activity, and this was eliminated by treatment with an IL-10-neutralizing Ab. Finally, when fibroblasts were transiently transfected with IL-10 antisense oligonucleotides, the conditioned medium lost its T cell anti-apoptotic effect, whereas medium from fibroblasts transfected with IFN-beta antisense oligonucleotides displayed the same anti-apoptotic activity of medium from untransfected fibroblasts. These results indicate that local fibroblast-derived IL-10 is critically involved in the survival of mucosal T cells, underscoring the crucial importance of studying organ-specific cells and products to define the mechanisms of immune homeostasis in specialized tissue microenvironments like the intestinal mucosa.
Ina
Kenji
K
Division of Medical Oncology, Nagoya Memorial Hospital, Nagoya University School of Medicine, Nagoya, Japan.
Kusugami
Kazuo
K
Kawano
Yasushi
Y
Nishiwaki
Tsuyoshi
T
Wen
Zhonghui
Z
Musso
Alessandro
A
West
Gail A
GA
Ohta
Michio
M
Goto
Hidemi
H
Fiocchi
Claudio
C
D017209:Apoptosis / Q000276:immunology*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005347:Fibroblasts / Q000276:immunology* / Q000378:metabolism; D006131:Growth Inhibitors / Q000502:physiology*; D006801:Humans; D016753:Interleukin-10 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D007376:Interleukin-2 / Q000502:physiology; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D007420:Intestine, Large / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D007421:Intestine, Small / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D019014:fas Receptor / Q000502:physiology*
D017077:Culture Media, Conditioned; D006131:Growth Inhibitors; D007376:Interleukin-2; D019014:fas Receptor; D016753:Interleukin-10