Background and Aims: Outcomes after Kasai portoenterostomy (KPE) for biliary atresia remain highly variable for unclear reasons. As reliable early biomarkers predicting KPE outcomes are lacking, we studied the prognostic value of FGF19. Approach and Results: Serum and liver specimens, obtained from biliary atresia patients (N=87) at KPE or age-matched cholestatic controls (N=26) were included. Serum concentration of FGF19 and bile acids, liver mRNA expression of FGF19, and key regulators of bile acid synthesis were related to KPE outcomes and liver histopathology. Immunohistochemistry and in situ hybridization were used for the localization of liver FGF19 expression. Serum levels (223 vs. 61 pg/mL, p<0.001) and liver mRNA expression of FGF19 were significantly increased in biliary atresia. Patients with unsuccessful KPE (419 vs. 145 pg/mL, p=0.047), and those subsequently underwent liver transplantation (410 vs. 99 pg/mL, p=0.007) had significantly increased serum, but not liver, FGF19, which localized mainly in hepatocytes. In Cox hazard modeling serum FGF19 <109 pg/mL predicted native liver survival (HR: 4.31, p<0.001) also among patients operated <60 days of age (HR: 8.77, p=0.004) or after successful KPE (HR: 6.76, p=0.01). Serum FGF19 correlated positively with increased serum primary bile acids (R=0.41, p=0.004) and ductular reaction (R=0.39, p=0.004). Conclusions: Increased serum FGF19 at KPE predicted inferior long-term native liver survival in biliary atresia and was associated with unsuccessful KPE, elevated serum primary bile acids, and ductular reaction.

Interleukin (IL)-8 (CXCL8), a chemokine involved in neutrophil recruitment, has been implicated in ductular reaction and liver fibrogenesis. We studied liver and serum IL-8 expression in a large biliary atresia (BA) cohort and explored its prognostic and pathophysiological potential. IL-8 expression was assessed in liver utilizing quantitative polymerase chain reaction (qPCR), immunohistochemistry and in situ hybridization and in serum using an enzyme-linked immunosorbent assay, among 115 BA patients, 10 disease controls and 68 normal controls. Results were correlated to portoenterostomy (PE) outcomes, biochemical and histological liver injury, transcriptional markers of fibrosis and cholangiocytes, and expression of other related cytokines. IL-8 was markedly overexpressed in liver and serum of BA patients at PE (n = 88) and in serum samples obtained during postoperative follow-up (n = 40). IL-8 expression in the liver was predominantly in cholangiocytes within areas of ductular reaction. Liver IL-8 mRNA expression correlated positively with its serum concentration, bile ductular proliferation, Metavir fibrosis stage, and transcriptional markers of activated myofibroblasts (ACTA2) and cholangiocytes (KRT19). Taken together, IL-8 may mediate liver injury in BA by promoting ductular reaction and associated liver fibrogenesis. Prognostic value of serum IL-8 to predict native liver survival was limited and confined to the postoperative period after PE.

Little is known on the mechanism of liver injury mediated by bile acids following Kasai portoenterostomy (KPE) in biliary atresia (BA). We sought to quantify individual serum bile acids, 7-alpha-hydroxy-4-cholesten-3-one (C4), and fibroblast growth factor 19 (FGF19) after KPE and to evaluate their prognostic utility and transcriptomic regulation. Serum (n=244) and liver specimens (n=105) prospectively obtained from BA patients (n=54) after KPE were included. Bile acids were analyzed using mass spectrometry, gene expression with quantitative PCR, and histopathology using a neural network model. Following KPE, serum bile acids correlated positively with biochemical liver injury, pediatric end-stage liver disease score, liver stiffness, histological ductular reaction, and liver fibrosis. Bile acids were higher among patients who developed portal hypertension (79.6 vs. 11.9 μmol/l, p<0.0001), esophageal varices (91.6 vs. 16.2 μmol/l, p<0.0001), or required liver transplantation (LT, 115.3 vs. 22.0 μmol/l, p<0.0001) during follow up; bile acids predicted these outcomes in time-dependent regression models. Accumulation of conjugated bile acids, cholic acid, and taurine conjugates predicted LT risk while associating with histological liver injury. Serum C4 (0.04 vs. 0.00 μmol/l, p=0.04) and liver CYP7A1 were higher in native liver survivors than in LT patients (fold-change 16.9 vs. 7.0, p=0.02). Primary bile acids correlated negatively with C4 (R=-0.38, p<0.001) and CYP7A1 (R=-0.49, p=0.01). Unlike in native liver survivors (R=-0.19, p=0.66), serum FGF19 correlated with liver FGF19 (R=0.59, p=0.04) without an inverse association with serum primary bile acids in LT patients (R=0.26, p=0.08). Accumulation and altered composition of serum bile acids predicted progressive liver disease and poorer transplant-free survival following KPE. Poor prognosis was associated with low bile acid synthesis and aberrantly increased liver FGF19. Biliary atresia (BA), a fibro-obliterating biliary disease of infants, remains the most common indication for pediatric liver transplantation caused by rapid progression of liver injury. To identify predictive biomarkers of disease progression and to elucidate the pathophysiology of BA liver injury, we profiled serum bile acids and studied their liver metabolism after Kasai portoenterostomy. Accumulation and altered composition of circulating bile acids predicted progression of liver disease and need for liver transplantation. Patients with poor prognosis showed low bile acid synthesis and abnormal liver expression of fibroblast growth factor 19.

Background: We aimed to quantify ductular reaction (DR) in biliary atresia using a neural network in relation to underlying pathophysiology and prognosis. Methods: Image-processing neural network model was applied to 259 cytokeratin-7–stained native liver biopsies of patients with biliary atresia and 43 controls. The model quantified total proportional DR (DR%) composed of portal biliary epithelium (BE%) and parenchymal intermediate hepatocytes (PIH%). The results were related to clinical data, Sirius Red–quantified liver fibrosis, serum biomarkers, and bile acids. Results: In total, 2 biliary atresia biopsies were obtained preoperatively, 116 at Kasai portoenterostomy (KPE) and 141 during post-KPE follow-up. DR% (8.3% vs. 5.9%, p=0.045) and PIH% (1.3% vs. 0.6%, p=0.004) were increased at KPE in patients remaining cholestatic postoperatively. After KPE, patients with subsequent liver transplantation or death showed an increase in DR% (7.9%–9.9%, p = 0.04) and PIH% (1.6%–2.4%, p = 0.009), whereas patients with native liver survival (NLS) showed decreasing BE% (5.5%–3.0%, p = 0.03) and persistently low PIH% (0.9% vs. 1.3%, p = 0.11). In Cox regression, high DR predicted inferior NLS both at KPE [DR% (HR = 1.05, p = 0.01), BE% (HR = 1.05, p = 0.03), and PIH% (HR = 1.13, p = 0.005)] and during follow-up [DR% (HR = 1.08, p<0.0001), BE% (HR = 1.58, p = 0.001), and PIH% (HR = 1.04, p = 0.008)]. DR% correlated with Sirius red–quantified liver fibrosis at KPE (R = 0.47, p<0.0001) and follow-up (R = 0.27, p = 0.004). A close association between DR% and serum bile acids was observed at follow-up (R = 0.61, p<0.001). Liver fibrosis was not prognostic for NLS at KPE (HR = 1.00, p = 0.96) or follow-up (HR = 1.01, p = 0.29). Conclusions: DR predicted NLS in different disease stages before transplantation while associating with serum bile acids after KPE.

Regardless of the underlying etiology and success of PE, progressive liver fibrosis and eventually cirrhosis represent the dominant pathology and the end-stage of BA. Ascending bile duct injury-induced cholestasis, inflammation and ductular reaction provide profibrogenic cytokine environment leading to myofibroblast activation and rapid progression of fibrosis especially after unsuccessful portoenterostomy. Although liver fibrosis and development of cirrhosis play a crucial role in determining BA outcomes, the exact prognostic significance and dynamics of mild to moderate liver fibrosis remain unclear. Manual scoring systems categorizing the degree of liver fibrosis are prone to intra- and interobserver variability, whereas novel combinations of digital pathology with artificial intelligence quantification can provide accurate information on fibrosis structure and dynamics at the level of individual collagen fibers. Although several studies have analyzed noninvasive assessment of fibrosis at time of PE, including imaging-based elastography and different serum biomarkers, current knowledge on their accuracy during the postoperative follow-up of BA is scarce. While therapeutic management of liver fibrosis in BA remains in its infancy, the resolution potential for liver fibrosis has been demonstrated after successful PE. Achievement of effective antifibrotic treatment may require combination of different therapies with complementary modes of action like anti-inflammatory medication, antioxidants and bile acid lowering agents.

Background & Aims: As better understanding of pathophysiology and reliable predictors for portal hypertension (PH) are needed, we investigated how histological ductular reaction (DR) and liver fibrosis predict PH in biliary atresia (BA). Methods: 60 BA patients treated between 1987 and 2024 at Helsinki University Hospital were enrolled. Patients underwent liver biopsies at Kasai portoenterostomy and 1 year postoperatively. PH was defined as endoscopic detection of oesophageal varices or thrombocytopenia (< 150*109) and splenomegaly. A neural network model was used to quantify proportional DR (DR%) relative to entire liver tissue, composed of cytokeratin‐7‐positive portal biliary epithelium (BE%) and parenchymal intermediate hepatocytes (PIH%). Fibrosis was measured by Metavir staging and computerized quantification of Sirius‐Red‐positive area (SRP%). Predictors of PH were studied with AUROC and survival analyses, and Cox regression models. Results: After portoenterostomy, PH was detected in 70% ( n = 42) of patients at median age 1.4 years (IQR 0.7–2.6). At portoenterostomy, DR% ≥ 6.9% ( p = 0.016) and PIH% ≥ 1.6% ( p < 0.001), but not liver fibrosis apart from cirrhosis ( n = 5) predicted PH ( p = 0.032). At 1 year, DR% ≥ 3.5% ( p < 0.001), PIH% ≥ 0.7% ( p < 0.001), BE% ≥ 3.2% ( p = 0.006) as well as Metavir 3–4 vs. 1–2 ( p = 0.037) and SRP% ≥ 28.4% ( p = 0.006) predicted PH. Patients with PH showed progression of PIH% ( p < 0.001) from portoenterostomy to follow‐up biopsy, accompanied by more rapid progression of fibrosis. In univariable regression models, different DR components, but not fibrosis, were associated with PH both at portoenterostomy and follow‐up also after successful portoenterostomy. Conclusion: DR predicted development of PH at and one year after portoenterostomy, associating with PH more consistently than fibrosis.