Analysis of cytokine functions in graft rejection by gene expression profiles.
BACKGROUND
The function of interferon (IFN)gamma in the regulation of the immune response after allogeneic transplantation is still poorly understood. Previous studies have suggested that IFNgamma can promote rejection and be important in tolerance induction.


METHODS
To analyze the various IFNgamma-dependent functions in terms of T helpers 1 and 2 responses during rejection, we investigated mice deficient in the transcription factors (signal transducer of activated T cells [STAT]4 and 6) and IFNgamma in fully major histocompatibility complex-mismatched vascularized cardiac transplants. Serum levels of the cytokines tumor necrosis factor-alpha, IFNgamma, and interleukin (IL)-1beta were evaluated by enzyme-linked immunosorbent assay, and the graft-infiltrating cells were examined by immunohistochemical staining. To analyze a large panel of immune parameters, we determined the expression of chemokines, chemokine receptors, and clusters of differentiation markers by RNAase protection assays. The data were analyzed with algorithms that generated hierarchic clustering dendrograms. Also, the expression profiles of individual genes were determined with self-organizing maps.


RESULTS
Our data show that both the STAT4- and STAT6-deficient groups have statistically prolonged graft survival (P<0.04 and P<0.01). Despite the absence of prolongation of graft survival in the IFNgamma-deficient group, our analysis of variance data show that more genes (18) were modulated in the IFNgamma-deficient group compared with the other two STAT4- and STAT6-deficient groups (five each).


CONCLUSIONS
Our results indicate that IFNgamma plays a distinct role in the modulation of gene expression that includes STAT4-independent mechanisms. Our study identifies eight genes (IL-1beta, IL-1RA, macrophage inflammatory protein-1beta, monocyte chemoattractant protein-1, CC-chemokine receptor (CCR)-1, CCR2, CCR5, and F4/80) that are highly expressed in all of our experimental groups. Thus, these genes become candidates for essential functions during rejection.
Liang
Yurong
Y
Laboratory of Molecular Immunology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02215, USA.
Christopher
Kenneth
K
DeFina
Rachel
R
Cidado
Justin
J
He
Hongzhen
H
Haley
Kathleen J
KJ
Finn
Patricia W
PW
Perkins
David L
DL
D000704:Analysis of Variance; D000818:Animals; D016207:Cytokines / Q000097:blood* / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D004195:Disease Models, Animal; D020869:Gene Expression Profiling / Q000379:methods; D006084:Graft Rejection / Q000235:genetics* / Q000276:immunology*; D006085:Graft Survival / Q000276:immunology*; D007371:Interferon-gamma / Q000172:deficiency / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D050797:STAT4 Transcription Factor; D050800:STAT6 Transcription Factor; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D013997:Time Factors; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics; D014184:Transplantation, Homologous / Q000276:immunology; D014185:Transplantation, Isogeneic / Q000276:immunology
D016207:Cytokines; D004268:DNA-Binding Proteins; D050797:STAT4 Transcription Factor; D050800:STAT6 Transcription Factor; C494091:Stat4 protein, mouse; C494100:Stat6 protein, mouse; D015534:Trans-Activators; D007371:Interferon-gamma