prominin-1-expressing Hepatic Progenitor Cells Promote Liver Fibrogenesis via mmp7-mediated Signaling Pathways During Cholestatic Liver Injury

Background: In Biliary Atresia (BA), intrahepatic biliary fibrosis commonly progresses to cirrhosis despite treatment. Matrix Metalloprotease-7 (MMP7) expression has been strongly linked to BA. We previously demonstrated that Prominin-1 (Prom1)-expressing hepatic progenitor cells (HPCs) give rise to profibrogenic intrahepatic ductular reactions associated with cholestatic injury, such as with BA. Hypothesis: Prom1+ HPCs and their lineage express MMP7 as part of signaling pathway activation associated with fibrogenesis.

Methods: RNA-Seq transcriptomic analysis was performed on PROM1-expressing HPCs from wildtype mice (WT), and their GFP-expressing progeny isolated from tamoxifen-treated Prom1Cre-Ert2;Rosa26Gfp C57BL/6J mice, after bile duct ligation (BDL, vs sham). BDL was also performed following targeted Diphtheria (DTA)-mediated ablation of Prom1-expressing cells in Prom1Cre-Ert2;Rosa26Dta transgenic mice with further analysis via qPCR.

Results: RNA-Seq analysis revealed top canonical pathways including leukocyte adhesion/diapedesis, hepatic fibrosis signaling, colorectal cancer metastasis signaling, and tumor microenvironment pathway. Mmp7 was significantly upregulated in BDL across the abovementioned canonical pathways. Mmp7 expression was significantly upregulated in PROM1+ HPC 5.79-fold with a False Discovery Rate (FDR)=0.008 and in GFP+ lineage of Prom1-expressing cells 18.41-fold, FDR=0.003 compared to sham. DTA-mediated ablation of Prom1-expressing cells resulted in decreased Collagen-1α (Col1a) expression following BDL compared to BDL alone (0.34±0.54 vs 7.55±4.26, p=0.002) similar to sham (0.60±0.40, p=0.96). Mmp7 was also lower in DTA/BDL ablated mice compared to BDL alone, but not significantly (0.17±0.17 vs 1.13±1.2, p=0.43).

Conclusion: Prom1-expressing HPCs may promote fibrogenesis during cholestatic liver injury in part via activation of MMP7-mediated pathways.