Genotype-Dependent APOL1 and Cytokine Profiles in Donor Kidneys During Normothermic Machine Perfusion

Background: The presence of two APOL1 renal risk variants (RRVs) in donor kidneys negatively impacts kidney allograft survival in a dose dependent manner. Normothermic machine perfusion (NMP) may allow resuscitation and improved assessment of kidneys before transplantation. We examined the effects of APOL1 RRVs on APOL1 expression and compared the differences in cytokine and APOL1 expression patterns between alternative preservation methods static cold storage (CS) and normothermic NMP. Methods: Nonutilized deceased donor kidney pairs from Black donors underwent 6-hour NMP (n=3) and CS (n=3) following CS. Renal perfusion, biochemical, and histologic parameters were recorded. NMP was directly compared with CS in paired donor kidneys using NMP with allogeneic red blood cells, followed by assessment of the aforementioned parameters, in addition to gene expression. DNA is extracted from the kidney samples and genotyping for APOL1 RRVs G1 (rs73885319) (rs60910145) and G2 (rs71785313) were performed by Sanger sequencing. Comparisons of continuous variables were assessed by Mann–Whitney U test. Results: Donor genotyping identified one kidney pair as homozygous for the G0 allele (G0/G0), one as heterozygous for the G1 RRV (G1/G0), and one as homozygous for the G2 RRV (G2/G2). All kidneys were successfully reperfused, and mRNA transcript levels of APOL1 related genes were subsequently measured. Significant differences in APOL1 gene expression were observed among all three groups of paired kidneys. In paired kidneys, mRNA expression varied significantly between G0/G0 and G2/G2 homozygous pairs. APOL1 expression shifted by a fold change of 2.43 under NMP conditions in the G2/G2 genotype (p<0.001). Inflammatory cytokine markers IFN-Gamma and IL-6 were both also significantly upregulated in the G2/G2 genotype kidneys, in both cold storage and NMP groups (p=0.001). Other related genes such as KIM-1 were upregulated by a fold change of 3.92 in the NMP group of the G2/G2 kidneys Conclusion: Donor kidneys with high-risk APOL1 genotypes, especially G2/G2, show increased APOL1 expression and inflammation, particularly under NMP. NMP enables detection of genotype-specific molecular changes, supporting its potential to improve donor kidney assessment before transplantation.