Abstract 31P
Background
Obesity is associated with systemic inflammation partly via metabolic reprogramming of macrophages that encircle adipocytes termed crown-like structures (CLS). This pro-inflammatory environment correlates to metabolic dysfunction that may promote tumour immune evasion. We previously showed that CLS were associated with poor survival in patients with HER2+ breast cancer (BC). However, the association between CLS and the spatial distribution of tumour infiltrating macrophages and T cells in BC is still not clear.
Methods
We investigated the association between CLS and immune cell signatures in early BC in the BeGIN cohort using multiplex immunohistochemistry and targeted RNA sequencing. Primary tumours (n=134) were stained for the expression of macrophage and T cell markers, and these were correlated to the presence of CLS. Immune cell densities and coordinates were extracted. 36 matched multiplexed tumours were selected for RNA sequencing using the HTG EdgeSeq Precision Immuno-oncology panel. Architect XD64 was used for digital pathology analysis. Bioinformatics and statistical analyses techniques were applied using R and STATA/IC.
Results
CLS were strongly associated with higher Body Mass, Fat Mass, and Fat Free Mass Indices (adjusted p<0.05). CLS were associated with a higher density of CD68+CD163+CD16+ macrophages in the tumour border, whereas CD68+CD163+CD16+CD32+ macrophages was the predominant population in the tumour core (adjusted p<0.05). A higher CD8/CD4 ratio was observed at the tumour border in the CLS patients (adjusted p<0.05). There was strong evidence of association between CLS and higher Foxp3+ regulatory T cell density at the border (adjusted p<0.05). CLS were associated with higher density of SMA+ fibroblasts in the core. In addition, high fibroblast density was positively correlated with Foxp3+ regulatory T cells in CLS patients. RNA sequencing showed that genes involved in cell proliferation were upregulated, whereas genes involved in the regulation of anticancer immunity were downregulated in CLS patients.
Conclusions
CLS were associated with an inflammatory border and aggressive molecular and immunosuppressive phenotypes in the core of the tumour.
Legal entity responsible for the study
The authors.
Funding
Cancer Research UK.
Disclosure
All authors have declared no conflicts of interest.