Resident CD24+LCN2+ LPCs aggravate fibrosis and inflammatory progression via the recruitment of TPPP3+COL10A1+ macrophages in NASH

Abstract

Resident CD24+LCN2+ liver progenitor cells (LPCs) reportedly contribute to the expanding ductular reaction and macrophage-mediated inflammation associated with chronic liver damage. Both ductular reactions and macrophage-driven inflammation are associated with liver fibrosis and injury in various mouse liver disorders. This study aims to investigate the molecular phenotypes of LPCs and their regulatory mechanisms in humans with non-alcoholic steatohepatitis (NASH). Single-cell RNA sequencing (scRNA-seq) datasets are used to characterize the status and molecular phenotypes of LPCs in clinical NASH samples. To elucidate the regulatory mechanisms of LPCs, CellChat and NicheNet are employed to assess cell-cell communication between LPCs and other cell types. The findings are validated using RNA sequencing datasets associated with NASH progression, NASH mouse models (CDAHFD and HFD), and human NASH liver samples. Results show that resident CD24+LCN2+ LPCs are identified and found to be significantly enriched in NASH patients. Cell communication analyses predict strong interactions between LPCs and proinflammatory macrophage subtypes. Additionally, in NASH, the liver recruits peripheral blood mononuclear cell (PBMC)-derived macrophages and polarizes them into proinflammatory subtypes. The macrophage subtype MP-2 is identified as the primary recipient of LPC-derived signals, exhibiting marked hyperactivation of the NF-κB pathway and a strong association with liver fibrosis. Finally, the MP-2 markers COL10A1 and TPPP3 are characterized and validated. In summary, this study reveals that resident CD24+LCN2+ LPCs are activated in NASH and contribute to fibrosis progression by promoting the activation of the proinflammatory COL10A1+TPPP3+ macrophage subtype.

1. Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly recognized liver disease worldwide, with a reported incidence of approximately 20%–30% [1,2]. MASLD comprises a continuum of liver conditions, ranging from benign metabolic dysfunction-associated steatosis to its progressive form characterized by inflammation and fibrosis, known as non-alcoholic steatohepatitis (NASH). The prevalence of NASH is high, and it poses a significant risk of progression to cirrhosis and hepatocellular carcinoma (HCC) [3,4]. Current guidelines recommend lifestyle modifications and a limited number of MASLD-specific pharmacological treatments, such as vitamin E and pioglitazone, for managing the disease [4]. However, there is no effective strategy for reversing NASH or improving fibrosis. Therefore, further research is needed to elucidate the underlying mechanisms of NASH and explore potential innovative therapeutic approaches.

Recent studies have demonstrated that the ductular reaction is associated with liver fibrosis and damage in various liver disorders, including NASH. This process is often accompanied by the activation of liver progenitor cells (LPCs), which express markers related to biliary epithelial cells and exhibit proliferative and inflammatory responses [5,6]. Our previous studies identified CD24+LCN2+ LPCs as the predominant resident LPCs contributing to the expanding ductular reaction and macrophage-mediated inflammation in chronic liver injury [7]. Emerging evidence suggests that crosstalk between resident LPCs and infiltrating immune cells promotes fibrogenesis through macrophage-derived profibrotic mediators, including TNF-α, NF-κB, and TGF-β [8–12]. This fibrotic reprogramming represents a key driver of NASH pathogenesis, as fibrosis is the strongest histological predictor of adverse clinical outcomes, including cirrhosis progression, transplant-free survival, and liver-related mortality. However, the mechanism by which LPC-activated inflammatory responses promote the pathogenesis of NASH remains unclear. Therefore, understanding the interactions between liver intrinsic LPCs and inflammatory cells as well as their impact on fibrosis is critical and may help reveal the pathological mechanisms of NASH. This may further lead to the development of new therapeutic strategies.