Dynamic changes in immune cell populations by AXL kinase targeting diminish liver inflammation and fibrosis in experimental MASH

Front Immunol. 2024 May 16:15:1400553. doi: 10.3389/fimmu.2024.1400553. eCollection 2024.

Abstract

Background and aims: Metabolic dysfunction-associated steatohepatitis (MASH) is a significant health concern with limited treatment options. AXL, a receptor tyrosine kinase activated by the GAS6 ligand, promotes MASH through activation of hepatic stellate cells and inflammatory macrophages. This study identified cell subsets affected by MASH progression and the effect of AXL inhibition.

Methods: Mice were fed chow or different fat-enriched diets to induce MASH, and small molecule AXL kinase inhibition with bemcentinib was evaluated. Gene expression was measured by qPCR. Time-of-flight mass cytometry (CyTOF) used single cells from dissociated livers, acquired on the Fluidigm Helios, and cell populations were studied using machine learning.

Results: In mice fed different fat-enriched diets, liver steatosis alone was insufficient to elevate plasma soluble AXL (sAXL) levels. However, in conjunction with inflammation, sAXL increases, serving as an early indicator of steatohepatitis progression. Bemcentinib, an AXL inhibitor, effectively reduced proinflammatory responses in MASH models, even before fibrosis appearance. Utilizing CyTOF analysis, we detected a decreased population of Kupffer cells during MASH while promoting infiltration of monocytes/macrophages and CD8+ T cells. Bemcentinib partially restored Kupffer cells, reduced pDCs and GzmB- NK cells, and increased GzmB+CD8+ T cells and LSECs. Additionally, AXL inhibition enhanced a subtype of GzmB+CD8+ tissue-resident memory T cells characterized by CX3CR1 expression. Furthermore, bemcentinib altered the transcriptomic landscape associated with MASH progression, particularly in TLR signaling and inflammatory response, exhibiting differential cytokine expression in the plasma, consistent with liver repair and decreased inflammation.

Conclusion: Our findings highlight sAXL as a biomarker for monitoring MASH progression and demonstrate that AXL targeting shifted liver macrophages and CD8+ T-cell subsets away from an inflammatory phenotype toward fibrotic resolution and organ healing, presenting a promising strategy for MASH treatment.

Keywords: GAS6; MERTK; TAM receptors; immune response; inflammation; liver fibrosis; mass cytometry.

MeSH terms

  • Animals
  • Axl Receptor Tyrosine Kinase*
  • Benzocycloheptenes / pharmacology
  • Benzocycloheptenes / therapeutic use
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / immunology
  • Disease Models, Animal
  • Liver / drug effects
  • Liver / immunology
  • Liver / pathology
  • Liver Cirrhosis* / drug therapy
  • Liver Cirrhosis* / immunology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Proto-Oncogene Proteins* / antagonists & inhibitors
  • Proto-Oncogene Proteins* / metabolism
  • Receptor Protein-Tyrosine Kinases* / antagonists & inhibitors
  • Receptor Protein-Tyrosine Kinases* / metabolism
  • Triazoles

Substances

  • Axl Receptor Tyrosine Kinase
  • AXL receptor tyrosine kinase, mouse
  • bemcentinib
  • Benzocycloheptenes
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • Receptor Protein-Tyrosine Kinases
  • Triazoles

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. Projects# RTI2018–095672-B-I00 and PID2021–123564OB-I00 to AM and PG funded by MCIN/AEI/10.13039/501100011033 and co-funded by “ERDF A way of making Europe”. Project# PI19/01410 and PI22/00475 to MM funded by Instituto de Salud Carlos III and co-funded by the European Union “ERDF A way of making Europe”; AGAUR (2021_SGR_490) and CERCA Programme/Generalitat de Catalunya, and Fundació la Marató de TV3 (202133–32).