Fractalkine,sCD40L,IL-4 And IP-10 In Bile As Potential Markers For Predicting Liver Injury After Liver Transplantation

ObjectiveAt present,up to 25% of the population suffers from viral infection,alcoholic and nonalcoholic steatohepatitis.Death caused by end-organ failure caused resulting from liver disease is increasing.In most cases,liver transplantation is the only effective treatment.Hepatic steatosis,donor age,organ ischemia time,and organ self-recovery are all potential risk factors for liver ischemia-reperfusion injury(IRI).Donors with these risk factors are labeled "marginal".Due to the shortage of donor organs and the increase in mortality while waiting for liver transplantation,the demand for these borderline types is also increasing.But at the same time,the chance of graft dysfunction or biliary complications after liver transplantation also increases.Bile is one of the important products of liver metabolism,which can reflect the state of liver cells on the other hand.With the continuous advancement of bile proteomics technology,bile’s constituents such as cytokines are expected to be used to judge the survival status of grafts and potential biomarkers after liver transplantation.Bile drainage tube is placed in most liver transplantation patients in China,and bile can be obtained within 2 hours after liver transplantation.Therefore,the main focus of this study is to find the degree of damage in the transplanted liver early,and to explore the predictive value of non-invasive liver damage markers in the bile for the degree of liver damage after liver transplantation.MethodsA total of 16 patients undergoing liver transplantation who were hospitalized in Center of Organ Transplantation,the Affiliated Hospital of Qingdao University,from January to December 2018 were enrolled,and according to the level of alanine aminotransferase(ALT)on day 1 after surgery.These patients were divided into mild liver injury(ALT < 500 U/L)group with 10 patients and severe liver injury(ALT > 500 U/L)group with 6 patients.Bile samples were collected on days 1,3,5 and 7 after liver transplantation.The levels of cytokines(Fractalkine、sCD40 L,IL-4,IP-10,MIP-α,MDC,FGF-2,IL-1β,IL-2,IL-17 A,IFN-γ,VEGF,G-CSF,IL-15,IL-8,IL-6,TGF-α)were measured by Milliplex(?) assay.The difference of cytokines in bile and clinical indexes were compared between the two groups.The R software was used to perform principal component analysis(PCA)of the bile cytokines and clinical indexes and gene ontology(GO)enrichment analysis of bile cytokines.The two independent sample t-test was used for comparison of normally distributed continuous data between two groups;the Mann-Whitney U test were used for comparison of non-normally distributed continuous date between two groups.A Spearman correlation analysis was used to evaluate the correlation between clinical indicators and bile cytokines.The ROC curve analysis was used to evaluate the predictive value of cytokines in bile and clinical indices for liver injury after liver transplantation.ResultsOn the first day,compared with mild liver injury,the severe liver injury group had significantly higher expression levels of Fractalkine(Z=-2.828,P=0.003),sCD40L(Z=-2.850,P =0.008),IL-4(Z=-2.398,P =0.017),IP-10(Z=-2.475,P =0.023)and MIP-1 α(Z=-1.844,P =0.043).The correlation analysis showed that on day 1 after liver transplantation,AST and ALT were positively correlated with the levels of several cytokines in bile(P<0.05).The area under the ROC cure of Fractalkine,sCD40 L,IL-4 and IP-10 were0.933(0.812～1.000),0.833(0.589～1.000),0.858(0.623～1.000),0.850(0.655～1.000)respectively,suggesting that Fractalkine,sCD40 L,IL-4 and IP-10 in bile on the first day after liver transplantation have significant predictive value for liver injury.The results of PCA showed that bile cytokines combined with clinical indexes on day 1 after liver transplantation could better distinguish the patients with mild from those with severe liver injury.GO analysis showed that bile cytokines were associated with positive feedback regulation of external stimulus,cell chemotaxis,receptor ligand activity,cytokine activity,cytokine-cytokine receptor interaction.ConclusionOn the first day,the levels of Fractalkine,sCD40 L,IL-4,IP-10 and MIP-α in bile after liver transplantation can reflect the level of liver damage.Fractalkine,sCD40 L,IL-4 and IP-10 might be served as potential biomarkers in the bile to diagnose liver injury after liver transplantation.Cytokines combined with clinical indicators can better predict the degree of liver injury after liver transplantation,and provide a theoretical basis for predicting liver injury after liver transplantation.