Spatial mapping of the hepatocellular carcinoma landscape identifies unique intratumoural perivascular-immune neighbourhoods
Authors: Marsh-Wakefield Felix , Santhakumar Cositha , Ferguson Angela L. , Ashhurst Thomas M. , Shin Joo-Shik , Guan Fiona H. X. , Shields Nicholas J. , Platt Barry J. , Putri Givanna H. , Gupta Ruta , Crawford Michael , Pulitano Carlo , Sandroussi Charbel , Laurence Jerome M. , Liu Ken , McCaughan Geoffrey W. , Palendira Umaimainthan 
Published: September 2023

AbstractBackground & AimsHepatocellular carcinoma (HCC) develops in the context of chronic inflammation, however, the opposing roles the immune system plays in both the development and control of tumours is not fully understood. Mapping immune cell interactions across the distinct tissue regions could provide greater insight into the role individual immune populations have within tumours.MethodsA 39-parameter imaging mass cytometry panel was optimised with markers targeting immune cells, stromal cells, endothelial cells, hepatocytes, and tumour cells. We mapped the immune landscape of tumour, invasive margin, and adjacent non-tumour regions across sixteen resected tumours comprising of 144 regions of interest. X-shift clustering and manual gating were used to characterise cell subsets, and Spectre quantified the spatial environment to identify cellular neighbourhoods. Ligand-receptor communication was quantified on two single-cell RNA-sequencing datasets and one spatial transcriptomic dataset.ResultsWe show immune cell densities remain largely consistent across these three regions, except for subsets of monocyte-derived macrophages which are enriched within the tumours. Mapping cellular interactions across these regions in an unbiased manner identifies immune neighbourhoods comprised of tissue-resident T cells, dendritic cells, and various macrophage populations around perivascular spaces. Importantly, we identify multiple immune cells within these neighbourhoods interacting with VEGFA+perivascular macrophages.VEGFAwas further identified as a ligand for communication between perivascular macrophages and CD34+endothelial cells.ConclusionsImmune cell neighbourhood interactions, but not cell densities, differ between intratumoural and adjacent non-tumour regions in HCC. Unique intratumoural immune neighbourhoods around the perivascular space points to an altered landscape within tumours. Enrichment of VEGFA+perivascular macrophages within these tumours could play a key role in angiogenesis and vascular permeability.Impact and ImplicationsWe investigated the landscape of immune cells within liver cancer. A unique perivascular neighbourhood of immune cells was identified. This is important as the interaction of immune cells and the vasculature in liver cancer is a therapeutic target of current systemic therapy. The characterisation in detail of this neighbourhood may potentially identify additional targets for future therapies.HighlightsImaging mass cytometry using 39 markers was used to map immune-infiltrating cells in hepatocellular carcinoma (HCC)Perivascular macrophages (PVM) were seen to form unique intratumoural neighbourhoods with immune cellsPVM were identified as VEGFA+within HCC tumours