Reduction of Foxp3-expressing regulatory T cell infiltrates during the progression of renal allograft rejection in a mouse model.
BACKGROUND
Regulatory T (Treg) cells are the immune suppressors in the maintenance of immune homeostasis and tolerance to self and non-self antigens, and may have therapeutic potential in the treatment of transplant rejection in patients. However, Treg cell development and action are poorly understood in transplantation. In this study, the association of CD4(+)Foxp3(+) infiltrates within renal allograft tissue with graft survival was investigated in a mouse model.


METHODS
Kidney donors from C57BL/6J mice (H-2(b)) were transplanted to bilaterally nephrectomized Balb/c recipient mice (H-2(d)). Treg cells were examined with FACS and immunohistochemical staining.


RESULTS
Here we showed that without any immunosuppressive regimen, kidney allografts were mostly rejected from 20 to 60 days after transplantation. During the progression of allograft rejection Foxp3(+) Treg phenotype infiltrates were significantly diminished, while intragraft expression of TGF-beta1, IL-6, IL-17 and IL-23 was up-regulated. The regulatory function of CD4(+)CD25(+) infiltrates was confirmed by their suppressive activity in mixed lymphocyte reaction. Further in vitro studies indicated that primary renal tubular epithelial cell (TEC) cultures produced high levels of IL-6 in response to allogeneic lymphocyte or IL-17 stimulation, and neutralization of IL-6 increased CD4(+)CD25(+)Foxp3(+) cells in co-cultures with TEC.


CONCLUSIONS
Diminution of Foxp3(+) Treg infiltrates associates with renal allograft rejection, and neutralization of IL-6 activity enhances Foxp3(+) Treg cell differentiation. Our findings suggest that increase in intragraft IL-6 may down-regulate infiltrating Foxp3(+) Treg cells.
Wang
Shuang
S
Department of Medicine, The University of Western Ontario, London, ON, Canada.
Jiang
Jifu
J
Guan
Qiunong
Q
Lan
Zhu
Z
Wang
Hao
H
Nguan
Christopher Y C
CY
Jevnikar
Anthony M
AM
Du
Caigan
C
D000818:Animals; D004195:Disease Models, Animal; D018450:Disease Progression; D051858:Forkhead Transcription Factors / Q000276:immunology / Q000378:metabolism*; D006084:Graft Rejection / Q000276:immunology*; D020381:Interleukin-17 / Q000276:immunology / Q000378:metabolism; D053759:Interleukin-23 / Q000276:immunology / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism; D007668:Kidney / Q000276:immunology; D016030:Kidney Transplantation / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D023001:Transplantation Tolerance / Q000276:immunology*; D014184:Transplantation, Homologous
D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D020381:Interleukin-17; D053759:Interleukin-23; D015850:Interleukin-6; D016212:Transforming Growth Factor beta