Fn14 hepatic progenitor cells are associated with liver fibrosis in biliary atresia

Integrative single-cell and spatial transcriptomic analyses identify a pathogenic cholangiocyte niche and TNFRSF12A as therapeutic target for biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA) is a devastating fibroinflammatory biliary disease that is the leading indication for pediatric liver transplants worldwide. Although cholangiocytes are the primary target cells, the pathogenic mechanisms involving cholangiocytes remain elusive. Here, we aimed to characterize the pathogenic role of cholangiocytes in BA.

APPROACH AND RESULTS

Integration of single-cell RNA sequencing of 12 liver tissues (from 9 BA and 3 controls) and the spatial transcriptome of another four liver sections (from 2 BA and 2 controls) provided a comprehensive spatial liver cell atlas of BA. In particular, we identified a cholangiocyte-enriched spatial niche with infiltration of activated HSCs, activated portal fibroblasts, macrovascular endothelial cells, and TREM2 + macrophages that were elevated in the portal triad of BA. This niche was positively correlated with bile duct profiles, liver fibrosis, and poor survival in 2 independent cohorts of patients with BA. Using integrative bioinformatics analyses to mine the cell-cell communication and regulatory network in BA cholangiocytes, we uncovered the fibroinflammatory phenotype of cholangiocytes with TNFSF12-TNFRSF12A as a significant signal. Genetic ablation or blockade of TNFRSF12A suppresses liver injury, inflammation, and bile duct profiles in a mouse model of disease. Using human biliary organoids, we revealed that BA organoids expressed higher levels of CCL2 in response to TNFSF12 stimulation and promoted monocyte chemotaxis via the CCL2-CCR2 axis.

CONCLUSIONS

Pathogenic cholangiocytes-enriched niche identifies TNFRSF12A as a potential therapeutic target for BA.

TWEAK/FN14 promotes profibrogenic pathway activation in Prominin-1-expressing hepatic progenitor cells in biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA), a congenital cholestatic liver disease, commonly culminates in end-stage liver disease. We previously demonstrated in BA that Prominin-1 ( Prom1 )-expressing hepatic progenitor cells (HPCs) expand within regions of developing fibrosis, giving rise to cholangiocytes within biliary ductular reactions. Null mutation of Prom1 or ablation of cells expressing Prom1 significantly diminishes fibrogenesis. FN14, the receptor for TNF-like weak inducer of apoptosis (TWEAK), is expressed by HPCs. TWEAK/FN14 signaling promotes fibrosis in multiple organ systems. Therefore, we hypothesized that TWEAK/FN14 signaling mediates Prom1 -expressing HPC proliferation leading to profibrogenic ductular reactions in BA.

APPROACH AND RESULTS

The experimental mouse model of BA mediated by perinatal rhesus rotavirus (RRV) infection resulted in increased co-expression of Fn14 in Prom1 -expressing HPCs within regions of ductular reactions. FN14 antagonist L524-0366 decreased ductular reactions, biliary fibrosis and periportal fibroblast activation in RRV injury. L524-0366 inhibition also demonstrated loss of downstream noncanonical NF-kB signaling expression in RRV injury. Murine HPC organoids demonstrated accelerated organoid growth and proliferation when treated with recombinant TWEAK. Increased organoid proliferation with recombinant TWEAK was lost when also treated with L524-0366. Analysis of a large publicly available RNA sequencing database of BA and normal control patients revealed significant increases in expression of PROM1 , FN14 , and genes downstream of TNF signaling and noncanonical NF-κB signaling pathways in BA infants. Infants who failed to achieve bile drainage after hepatoportoenterostomy had higher relative levels of FN14 expression.

CONCLUSION

TWEAK/FN14 signaling activation in Prom1 -expressing HPCs contributes to proliferation of profibrogenic ductular reactions in BA.

mRNA and lncRNA expression profiles of liver tissues in children with biliary atresia

Progressive liver fibrosis is the most common phenotype in biliary atresia (BA). A number of pathways contribute to the fibrosis process so comprehensive understanding the mechanisms of liver fibrosis in BA will pave the way to improve patient's outcome after operation. In this study, the differentially expressed profiles of mRNAs and long non-coding RNAs from BA and choledochal cyst (CC) liver tissues were investigated and analyzed, which may provide potential clues to clarify hepatofibrosis mechanism in BA. A total of two BA and two CC liver tissue specimens were collected, the expression level of mRNAs and lncRNAs was detected by RNA sequencing. Differentially expressed mRNAs (DEmRNAs) were functionally annotated and protein-protein interaction networks (PPI) was established to predict the biological roles and interactive relationships. Differentially expressed lncRNAs (DElncRNAs) nearby targeted DEmRNA network and DElncRNA-DEmRNA co-expression network were constructed to further explore the roles of DElncRNAs in BA pathogenesis. The expression profiles of significant DEmRNAs were validated in Gene Expression Omnibus database. A total of 2,086 DEmRNAs and 184 DElncRNAs between BA and CC liver tissues were obtained. DEmRNAs were enriched in 521 Gene Ontology terms and 71 Kyoto Encyclopedia of Genes and Genomes terms which were mainly biological processes and metabolic pathways related to immune response and inflammatory response. A total of five hub proteins (TYRO protein tyrosine kinase binding protein, C-X-C motif chemokine ligand 8, pleckstrin, Toll-like receptor 8 and C-C motif chemokine receptor 5) were found in the PPI networks. A total of 31 DElncRNA-nearby-targeted DEmRNA pairs and 2,337 DElncRNA-DEmRNA co-expression pairs were obtained. The expression of DEmRNAs obtained from RNA sequencing were verified in GSE46960 dataset, generally. The present study identified key genes and lncRNAs participated in BA associated liver fibrosis, which may present a new avenue for understanding the patho-mechanism for hepatic fibrosis in BA.

The clinical, prognostic and therapeutic significance of liver cancer stem cells and their markers

Hepatocellular carcinoma (HCC) is the fourth most common cause of death among cancers. The poor prognosis of HCC might be caused by a population of cancer stem cells (CSC). CSC have similar characteristics to normal stem cells and are responsible for cancer recurrence, chemoresistance, radioresistance and metastasis. Liver cancer stem cells (LCSC) are identified via specific surface markers, such as CD44, CD90, CD133, and EpCAM (CD326). Recent studies suggested a complex interaction between mentioned LCSC markers and clinical features of HCC. A high expression of CSC is correlated with a negative prognostic factor after surgical resection of HCC and is connected with more aggressive tumor behavior. Moreover, LCSC might be responsible for increasing resistance to sorafenib, a kinase inhibitor drug. A reduction in the LCSC population may be crucial to successful advanced HCC therapy.

TWEAK/Fn14 axis is an important player in fibrosis

Fibrosis is a common pathological condition associated with abnormal repair after tissue injury. However, the etiology and molecular mechanisms of fibrosis are still not well-understood. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) belongs to the TNF superfamily and acts by binding to its receptor, fibroblast growth factor-inducible 14 (Fn14), thereby activating a variety of intracellular signal transduction pathways in various types of cells. Besides promoting the expression of growth factors, activation of TWEAK/Fn14 signaling after tissue injury can promote the expression of pro-inflammatory cytokines, which trigger the immune response, thereby exacerbating the injury. Severe or repetitive injury leads to a dysregulated tissue repair process, in which the TWEAK/Fn14 axis promotes the activation and proliferation of myofibroblasts, induces the secretion of the extracellular matrix, and regulates profibrotic mediators to further perpetuate and sustain the fibrotic process. In this review, we summarize the available experimental evidence on the underlying molecular mechanisms by which the TWEAK/Fn14 pathway mediates the development and progression of fibrosis. In addition, we discuss the therapeutic potential of the TWEAK/Fn14 pathway in fibrosis-associated diseases based on evidence derived from multiple models and cells from injured tissue and fibrotic tissue.

The effect of APTR, Fn14 and CD133 expressions on liver fibrosis in biliary atresia patients

PURPOSE

Although some biomarkers of hepatic progenitor cells have been reported to be involved in the liver fibrosis in patients with biliary atresia (BA), however, research still shows conflicting results. Therefore, we investigated the effect of Alu-mediated p21 transcriptional regulator (APTR), fibroblast growth factor-inducible 14 (Fn14) and CD133 expressions on liver fibrosis in Indonesian BA patients.

METHODS

Nineteen liver samples from BA patients and 9 liver specimens from non-BA controls were obtained. The expressions of APTR, Fn14 and CD133 were analyzed by quantitative real-time polymerase chain reaction (qPCR).

RESULTS

APTR expression was strongly up-regulated (1.5-fold) in liver BA specimens compared to liver controls (ΔC_T 3.2 ± 0.6 vs 3.8 ± 0.51; p = 0.028). Moreover, Fn14 and CD133 expressions were similar in the BA and control groups (ΔC_T 2.7 ± 1.3 vs. 1.4 ± 1.6, p = 0.07; and 12.0 ± 3.7 vs. 11.78 ± 2.30, p = 0.88, respectively). Intriguingly, CD133 expression was strongly related with the survival of BA patients (p = 0.0061), but not with age at Kasai procedure (p = 0.36) and the presence of cirrhosis (p = 0.77).

CONCLUSION

We present the first study of aberrant APTR expressions in the liver of BA infants which might contribute to liver fibrogenesis in BA infants.