Intrahepatic immune microenvironment contributes to spontaneous tolerance in pediatric liver transplantation recipients

We carried out a cross-sectional study using clinical data and biospecimens to analyze factors that were associated with immune tolerance after pediatric liver transplantation. Multivariable analysis revealed that peripheral Treg ratio (OR=2.48 (1.55-19.8), p=0.032) and maximum blood EBV-DNA copy (OR=5.53 (1.08-5.67), p=0.008) were associated with the development of tolerance during follow-up, while serum IGM titer (OR=0.73 (0.53-0.99), p=0.046) had a negative relation with tolerance. Histological evaluation indicated no difference on hepatocyte damage, portal inflammation and fibrosis stage between tolerant and non-tolerant recipients. Meanwhile, no deterioration of hepatic pathology was found in recipients with longer follow-up time. Further allograft biopsy transcriptome analysis exhibited distinguished intrahepatic expression patterns between tolerant and non-tolerant recipients. Tolerant allografts were characterized by low expression of cytotoxic and inflammatory genes (like NDUFAF2, MAN1A2, PLEK2, NUDFB4 and FCER1G) and high levels of immune regulatory ones (like SCRIB, MAPK8IP3, TSC2, CHRNA4 and D2HGDH). Especially, immunohistology staining confirmed the upregulated expression of CD39 (ENTPD1) and CD73 (NT5E) in liver sinusoidal endothelial cells and hepatocytes from tolerant allograft, which was associated with increased CD4+ Treg ratio in portal areas.