Measurement of Feline Cytokine Gene Expression in a Model of Feline Renal Transplantation
Renal transplantation is currently an accepted treatment option for cats with acute and chronic renal failure. Following successful transplantation and immunosuppression consisting of cyclosporine (CyA) and corticosteroids (Dex), the incidence of acute rejection in the cat can be as high as 26%. Recent studies in the human literature have found that cytokines produced by T cells play a critical role in transplantation immunology particularly in the area of kidney rejection.
The purpose of this study was to evaluate the effects of current immunosuppressive therapy including CyA and Dex as well as a novel immunosuppressive agent, (hu)CTLA4-Ig, on cytokine production in an in vitro feline model.
Peripheral blood (3-4ml) was collected from 16 healthy cats and the peripheral blood mononuclear cells (PBMC) isolated by density gradient centrifugation. Peripheral blood mononuclear cells were plated in triplicate at a concentration of 2 x 106cells/mL and stimulated with either the mitogen Con A (10µg/ml) alone or Con A in the presence of CyA (0.05µg/ml), Dex (1x10-7M), a combination of CyA and Dex or (hu)CTLA4-Ig (10µg/ml). An ELISA was performed from the supernatant for INFγ, GM-CSF, IL-4 and IL-10. Pairwise comparisons were performed using the Wilcoxan signrank test with significance set at p<0.05.
Compared to mitogen alone, CyA, Dex, the combination of CyA and Dex and (hu)CTLA4-Ig all caused a significant decrease in INF-γ and GM-CSF production. CyA and the combination of CyA and Dex caused a significant decrease in IL10 production. No significant difference in IL4 production in the presence of any drug compared to stimulus alone was identified.
The percutaneous needle biopsy remains the gold standard for diagnosing acute rejection in both human and veterinary patients, but it is an invasive procedure and complications can occur. In human transplantation, the evaluation of cytokine production from blood or urine can be useful in detecting acute rejection at a stage sufficiently early to allow therapeutic intervention. Results from this study may be useful in developing a similar noninvasive test that would be invaluable for the evaluation of the feline renal transplant patient.
Originally presented at the ACVS Symposium, Chicago, IL, October 2007