This abstract was presented at the 2024 annual meeting of the Danish Society of Nephrology.
Authors:
Qais Waleed Saleh 1,2
Martin Tepel 1,2
Affiliations:
1 – Department of Nephrology, Odense University Hospital, Odense Denmark.
2 – Institute of Molecular Medicine, Department of Renal and Cardiovascular Research, University of Southern Denmark, Odense, Denmark.
Introduction:
Patients suffering from chronic kidney disease (CKD) are known to suffer from immune dysregulation. Numerous mechanisms may underline the immune dysregulation found in CKD, including alteration of the transcriptome. The forkhead box P3 transcription factor (FOXP3) is essential for modulation of the immune system, and its actions include the regulation of tolerance of self- and non-self-antigens. It is unknown if FOXP3 RNA splicing is altered in CKD patients. Here, we explored the effect of end stage CKD on the FOXP3 transcriptome.
Methods:
We measured mature- and pre-mature FOXP3 mRNA levels in peripheral blood samples of kidney transplant candidates using quantitative polymerase chain reactions. All participants were 18 years old or older and were recruited from Odense University Hospital. FOXP3 levels were determined relative to sex-matched healthy kidney donor controls using the 2–ΔΔCq method (Cq = mean quantification cycle). Finally, subgroup analysis was conducted according to the relative difference in mature mRNA FOXP3 expression levels, according to those who produce more total mature mRNA FOXP3 relative to controls (2–ΔΔCq value > 1) and those who produce less (2–ΔΔCq value < 1).
Results:
We measured FOXP3 mRNA levels in 315 kidney transplant candidates, 103 (33 %) females and 212 (67 %) males. The control group consisted of 60 (59 %) healthy female kidney donors and 41 (41 %) healthy male kidney
donors. Median mature FOXP3 mRNA levels in kidney transplant candidates were lower than in controls (median fold difference 0.79, 95 % Confidence interval (CI) 0.48-1.24), while median pre-mature FOXP3 mRNA levels were higher in kidney transplant candidates compared to controls (median fold difference 2.04, 95 %CI 1.26-3.16). In comparison to kidney transplant candidates who exhibited lower mature FOXP3 expression compared to healthy controls (N = 205, 75.1 %), Kidney transplant candidates who exhibited higher mature FOXP3 mRNA levels compared to controls (N = 110, 34.9 %) were older (median age 56, 95 % CI 44-64 vs. 48, 95 % CI 61, p < 0.01), were treated with dialysis for a shorter period of time (median months on dialysis 10, 95 % CI 2-19 vs. 12, 95 % CI 5-25, p = 0.03), were less likely to be treated with hemodialysis (50 or 45 % treated with hemodialysis vs 123 or 60 %, p = 0.03), and more likely to be treated with diuretics (79 or 75 % treated with hemodialysis vs 113 or 55 %, p < 0.01).
Conclusion:
Chronic kidney disease seems to alter the RNA splicing and transcription of FOXP3. The effect seems to be associated with increasing age, treatment with hemodialysis and by longer periods of dialysis treatment. Given the essential role of FOXP3 in immunomodulation, our findings highlight the need to explore potential FOXP3 related mechanisms that may contribute to the immune dysregulation found in CKD patients.
Figure 1: Levels of mature – and pre-mRNA Forkhead box P3 (FOXP3) in kidney transplant candidates relative to levels in healthy kidney donors.