Changes of CD4+CD25+ regulatory T cells and related regulatory factors in acute renal allograft rejection in rats

Abstract

Objective To observe the level of CD4+CD25+ regulatory T cells (CD4+CD25+ Treg cells) with positive fork head transcription factor 3 (Foxp3) and changes of T-box transcription factor TBX1 (TBX1) and myocyte specific enhancer 2D (MEF2D) expression in peripheral blood of rats with acute rejection after renal transplantation, and to investigate its regulatory mechanisms by combined with renal function, plasma interleukin-10 (IL-10), interferon-γ (IFN-γ) and renal histopathological changes. Methods Rat renal transplantation model was established and divided into two groups: acute rejection group (AR group) and non-acute rejection group (non-AR group). Their renal function including serum creatinine (Scr) and blood urea nitrogen (BUN) in plasma was measured. The renal histopathology was observed by HE staining. Levels of IL-10 and IFN-γ in plasma were detected by ELISA. The proportion of CD4+CD25+ Treg cells was measured by flow cytometry. The mRNA expressions of Foxp3, TBX1 and MEF2D in CD4+CD25+ Treg cells were detected by real-time PCR, and their protein expressions were tested by Western blotting. Results Compared with those in the non-AR group, the levels of BUN, Scr and IFN-γ significantly increased in AR group (all P<0.05), while IL-10 decreased (P<0.05). Renal histopathology in the acute rejection group showed glomerular hypertrophy and mesangial cell proliferation, capillary proliferation and neutrophil infiltration; renal interstitial edema and tubular necrosis, accompanied by lymphocytes, plasma cells and neutrophils infiltration. Compared with that in the non-AR group, the percentage of CD4+CD25+ Treg cells in peripheral blood was notably lowered in AR group (4.50%±0.50% vs 5.74%±1.96%, P<0.05). The mRNA and protein expressions of Foxp3 and MEF2D were lower in AR group than those in non-AR group, while the expressions of TBX1 was elevated (all P<0.05). Conclusions In rats with acute renal allograft rejection, the percentage of CD4+CD25+ Treg cells and expressions of Foxp3, MEF2D and IL-10 decrease, while the expressions of TBX1 and IFN-γ enhance. These participate in the development of acute rejection after renal transplantation, and aggravate the renal damage. Key words: Graft rejection; T-lymphocytes; Forkhead transcription factors; T-box domain proteins; MEF2 transcription factors