Research News

Researchers Generated a Spatiotemporal Atlas of Cholestatic Injury and Repair in Mice

Source: Time: 2024-04-18

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, together with BGI Research, Hangzhou systematically analyzed regional heterogeneity and signaling interactions during cholestatic injury and repair in mouse liver. The researchers revealed a key role of cholangiocyte-driven signaling correlating with the periportal damage-repair response and found that Atoh8 restricts hepatocyte proliferation during DDC damage.

The mammalian liver is composed of repetitive structural unit of liver lobules. Lobules, possessing regionally specialized metabolic functions along the center to the peripheral, 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.

3,5-Diethoxycarbonyl-1,4-dihydro-collidin (DDC) treatment, which induces periportal injury by interlobular bile duct obstruction, is used to model human cholestatic diseases. DDC-induced cholestasis is also accompanied by impaired hepatocyte proliferation, which is gradually restored after DDC withdrawal. However, 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. Stereo-seq, a DNA nanoball-based method, possesses single-cell resolution and a large field-of-view.

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 and single-cell transcriptomics. The results suggest 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. The data also suggested the heterogeneity of liver progenitor-like cells (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. Additionally, researchers identified a negative regulator of hepatocyte proliferation, Atoh8, knockdown of which led to an increased number of Ki67+ hepatocytes during DDC injury.

In summary, the analysis suggested that cholangiocytes function as a signaling “hub” in regional injury, LAM recruitment, hepatocyte reprogramming, and hepatocyte regeneration. Moreover, researchers identified Atoh8 as a regulator of hepatocyte proliferation during the switch from injury to repair. These findings lay a keystone for in-depth studies of cellular dynamics and molecular mechanisms of cholestatic injuries, which may further develop into therapies for cholangiopathies.