In a study published in Nature Genetics, researchers led by Prof. HUI Lijian from the Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology of the Chinese Academy of Sciences, and the collaborators, systematically analyzed regional heterogeneity and signaling interactions during cholestatic injury and repair in mouse liver, and revealed a key role of cholangiocyte-driven signaling correlating with the periportal damage-repair response and that Atoh8 restricts hepatocyte proliferation during 3,5-Diethoxycarbonyl-1,4-dihydro-collidin (DDC) damage.

The mammalian liver is composed of repetitive structural unit of liver lobules which are prone to typical region-specific injuries. Cholestatic liver injuries, characterized by regional damage around the bile ductular region, lack curative therapies and cause considerable mortality. Given the complicated cell-cell interactions in cholangiopathies and the active role of cholangiocytes, it is necessary to address underlying interplays between cholangiocytes and neighboring cells, including non-parenchymal cells and periportal hepatocytes.

DDC treatment is used to model human cholestatic diseases. DDC-induced cholestasis is accompanied by impaired hepatocyte proliferation which is gradually restored after DDC withdrawal. Without spatial resolution, it is difficult to determine how niche signals control these region-specific cholangiopathies. The development of spatial transcriptomic technologies has enabled the determination of spatial distribution of gene expression and cell-cell interactions. 

In this study, the researchers generated a high-definition spatiotemporal atlas of gene expression during cholestatic injury and repair in mice by integrating Stereo-seq, a DNA nanoball-based method, possessing single-cell resolution and a large field-of-view, and single-cell transcriptomics.

Through spatiotemporal interaction analyses, they found that cholangiocytes were involved in the greatest number of ligands, receptors and signalings among all cell types in the periportal region. They highlighted that cholangiocytes play a key role in shaping the immune cell components in the periportal region, including enhancing immune cell recruitment by Ccl2, Cxcl1 and Cxcl5 and promoting lipid-associated macrophage (LAM) differentiation by Csf1. LAM-secreting Tnfsf12 relayed positive feedback to the cholangiocytes.

Liver progenitor-like cells (LPLCs) were clustered into two subtypes in the scRNA-seq and spatial domain, suggesting the heterogeneity of LPLCs. LPLC2 were transcriptomically similar to cholangiocytes and were located closer to cholangiocyte domain compared to LPLC1, implying a possible functional interaction between LPLC2 and cholangiocytes. Cholangiocytes strongly expressed Tgfb2, which may account for the activation of the TGFb signaling in LPLC2.

In addition, they identified a negative regulator of hepatocyte proliferation, Atoh8, knockdown of which led to an increased number of Ki67⁺ hepatocytes during DDC injury.

These findings suggested that cholangiocytes function as a signaling “hub” in regional injury, LAM recruitment, hepatocyte reprogramming, and hepatocyte regeneration. The researchers identified Atoh8 as a regulator of hepatocyte proliferation during the switch from injury to repair.

This study lays the foundation for in-depth studies of cellular dynamics and molecular mechanisms of cholestatic injuries, which may further develop into therapies for cholangiopathies.