Guicciardi, Maria E

Cholangiocyte pathophysiological activation was examined in a model of murine cholestasis. CX3CR1 + macrophages are recruited to the periportal region, likely mediated by cholangiocyte expression of CX3CL1. Cholangiocyte transcriptomics from cholestatic mice display activation of a “pathogen-induced cytokine storm” pathway, and exhibit activation of the transcription factor NF-Y. In human cholangiocytes, NF-Y promotes expression of the profibrogenic ligand TGFβ1. These observations provide insights into the cholestatic cholangiocyte pathobiology contributing to periductal inflammation and fibrosis.

Background: The pathogenesis of primary sclerosing cholangitis (PSC) is unclear, although studies implicate IL-17A as an inflammatory mediator in this disease. However, a direct assessment of IL-17 signaling in PSC cholangiocytes is lacking. In this study, we aimed to investigate and characterize the response of PSC extrahepatic cholangiocyte organoids (ECO) to IL-17A stimulation. Methods: Cholangiocytes obtained from patients with PSC and without PSC by endoscopic retrograde cholangiography were cultured as ECO. The ECO were treated with vehicle or IL-17A and assessed by transcriptomics, secretome analysis, and genome sequencing. Results: Unsupervised clustering of all integrated single-cell RNA sequencing data identified 8 cholangiocyte clusters that did not differ between PSC and non-PSC ECO. However, PSC ECO cells demonstrated a robust response to IL-17 treatment, as noted by an increased number of differentially expressed genes by transcriptomics and more abundant chemokine and cytokine expression and secretion. After rigorous filtering, genome sequencing identified candidate somatic variants shared among PSC ECO from unrelated individuals. However, no candidate rare variants in genes regulating the IL-17 pathway were identified, but rare variants regulating the MAPK signaling pathway were present in all PSC ECO. Conclusions: PSC and non-PSC patient-derived ECO respond differently to IL-17 stimulation, implicating this pathway in the pathogenesis of PSC.