Cholangiocyte senescence in primary sclerosing cholangitis is associated with disease severity and prognosis.

Background & Aims: Primary sclerosing cholangitis (PSC) is a rare cholangiopathy of unknown aetiopathogenesis. The aim of this study was to evaluate cellular senescence (CS) marker expression in cholangiocytes of patients with PSC and their correlation with clinical-pathological features and prognosis.

Methods: Thirty-five patients with PSC with at least 1 available liver sampling were included. Clinical laboratory data at the time of liver sampling were collected. The endpoints were survival without liver transplantation (LT), time to LT, and survival without LT or cirrhosis decompensation. Histological grading and staging were assessed according to Nakanuma. Immunohistochemical stains for CS markers, p16INK4A (p16) and p21WAF1/Cip1 (p21), were performed and scored by a 3-tier scale based on positivity extent in native bile duct (NBD) and ductular reaction (DR).Results: p16 expression in NBD and DR was directly correlated with fibrosis ( p  ≤0.001 for both) and stage ( p  = 0.006 and p  <0.001, respectively). Moreover, p16 in NBD was positively correlated with hepatitis activity (HA) ( p  = 0.026), whereas p16 in DR was directly correlated with bile duct loss (BDL) ( p  = 0.005) and metaplastic hepatocytes (MH) ( p  <0.01). p21 expression in NBD and DR was directly correlated with HA ( p  = 0.004 and p  = 0.043, respectively), fibrosis ( p  = 0.006 and p  <0.001, respectively), stage ( p  = 0.006 and p  = 0.001, respectively), BDL ( p  = 0.002 and p  = 0.03, respectively), and DR and MH ( p  ≤0.004 for all). By multivariate analysis, p16 expression in DR was independently associated with stage ( p  = 0.001), fibrosis ( p  = 0.001), and BDL ( p  = 0.011). p21 expression in NBD was independently associated with HA ( p  = 0.012), BDL ( p  = 0.04), and DR ( p  = 0.014). Finally, p21 expression in DR was independently associated with LT-free survival, time to LT, and adverse outcome-free survival ( p  = 0.001, p  = 0.017, and p  = 0.001, respectively).

Conclusions: Cholangiocyte senescence is detectable in all stages of PSC and is associated with histological and clinical disease severity, potentially representing a new prognostic and therapeutic target.

Lay summary: In this study, we showed that cholangiocyte senescence (CS), previously demonstrated in liver of patients with end-stage primary sclerosing cholangitis (PSC), is an early event and is detectable in all disease stages. Moreover, we observed that CS is associated with histological and clinical disease severity and patients' outcome. Thus, we suggest that CS may represent a new prognostic tool and a potential therapeutic target in PSC.

Clinical trial number: Protocol number 0034435, 08/06/2020.