Cholestatic liver injury is associated with intrahepatic biliary fibrosis, which can progress to cirrhosis. Resident hepatic progenitor cells (HPCs) expressing Prominin‐1 (Prom1 or CD133) become activated and participate in the expansion of cholangiocytes known as the ductular reaction. Previously, we demonstrated that in biliary atresia, Prom1(+) HPCs are present within developing fibrosis and that null mutation of Prom1 significantly abrogates fibrogenesis. Here, we hypothesized that these activated Prom1 ‐expressing HPCs promote fibrogenesis in cholestatic liver injury. Using Prom1 CreERT2‐nLacZ/+ ;Rosa26 Lsl‐GFP/+ mice, we traced the fate of Prom1 ‐expressing HPCs in the growth of the neonatal and adult livers and in biliary fibrosis induced by bile duct ligation (BDL). Prom1 ‐expressing cell lineage labeling with Green Fluorescent Protein (GFP) on postnatal day 1 exhibited an expanded population as well as bipotent differentiation potential toward both hepatocytes and cholangiocytes at postnatal day 35. However, in the adult liver, they lost hepatocyte differentiation potential. Upon cholestatic liver injury, adult Prom1 ‐expressing HPCs gave rise to both PROM1(+) and PROM1(‐) cholangiocytes contributing to ductular reaction without hepatocyte or myofibroblast differentiation. RNA‐sequencing analysis of GFP(+) Prom1 ‐expressing HPC lineage revealed a persistent cholangiocyte phenotype and evidence of Transforming Growth Factor‐β pathway activation. When Prom1 ‐expressing cells were ablated with induced Diphtheria toxin in Prom1 CreERT‐nLacZ/+ ;Rosa26 DTA/+ mice, we observed a decrease in ductular reactions and biliary fibrosis typically present in BDL as well as decreased expression of numerous fibrogenic gene markers. Our data indicate that Prom1 ‐expressing HPCs promote biliary fibrosis associated with activation of myofibroblasts in cholestatic liver injury.

SummaryMaximum extraction stress and integrated extraction work were measured for sutures implanted for 3, 7, and 14 day periods. Six common non-absorbable sutures, representative of braided and monofilamentary forms, were implanted subdermally and were used for cutaneous incision closure with purebred pointer dogs. The data show: ( 1 ) Braided sutures, polyester/Teflon, silk-type B, and silk-silicone interacted with peripheral tissue to a significantly greater degree than the monofilamentary types, nylon, polypropylene, and polyethylene; ( 2 ) polyester-Teflon braided suture interacted to a lesser degree than the other braided sutures; (3) the relatively intense interaction of plain silk and siliconetreated silk appears to reflect the combined effects of mechanical aspects of braiding and of biochemical response; and (4) all braided sutures swelled over the implantation periods with as much as a 70% increase in diameter after 14 days for silk.

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

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Background and Aims: Restitution of the extrahepatic biliary luminal epithelium in cholangiopathies is poorly understood. Prominin-1 (Prom1) is a key component of epithelial ciliary body of stem/progenitor cells. Given that intrahepatic Prom1-expressing progenitor cells undergo cholangiocyte differentiation, we hypothesized that Prom1 may promote restitution of the extrahepatic bile duct (EHBD) epithelium following injury. Approach and Results: Utilizing various murine biliary injury models, we identified Prom1-expressing cells in the peribiliary glands of the EHBD. These Prom1-expressing cells are progenitor cells which give rise to cholangiocytes as part of the normal maintenance of the EHBD epithelium. Following injury, these cells proliferate significantly more rapidly to re-populate the biliary luminal epithelium. Null mutation of Prom1 leads to significantly >10-fold dilated peribiliary glands following rhesus rotavirus–mediated biliary injury. Cultured organoids derived from Prom1 knockout mice are comprised of biliary progenitor cells with altered apical-basal cellular polarity, significantly fewer and shorter cilia, and decreased organoid proliferation dynamics consistent with impaired cell motility. Conclusions: We, therefore, conclude that Prom1 is involved in biliary epithelial restitution following biliary injury in part through its role in supporting cell polarity.