Fig. 4: TREM2 + TAMs exhibit elevated lipid metabolism and are induced by oxLDL produced from metabolism archetype cancer cells.

A Gene set enrichment analysis (GSEA) on genes ranked by log2 fold change between TREM2⁺TAMs and other TAM clusters. B Dotplot shows the expression of selected genes belonging to the indicated biological process in TAM subsets. C Flow cytometry of TREM2 and SPP1 expression in macrophages treated with TIF ± Na₂CO₃ or lipid removal reagent (Cleanascite). D Bodipy, TREM2, and SPP1 staining on HCC frozen sections. Scale bar, 500 μm (left), 100 μm (right). Images are representative of n = 2 HCC samples. E Heatmap summarizing TREM2, SPP1 expression (mean of n = 3 biological replicates, upper) and supernatant SPP1 concentrations (lower) in BMDMs or TAMs treated with indicated lipids. F Relative TREM2, SPP1 mRNA (left), protein expression (middle), and supernatant SPP1 concentration (right) in BMDM or TAM treated with vehicle or oxLDL (25 or 50 μg/mL). G Transwell migration and evasion assays of Hepa1–6 co-cultured with BMDM or TAM treated with vehicle, LDL (50 μg/mL) or oxLDL (50 μg/mL) ± SPP1 antibody (1 μg/mL). Scale bar, 100 μm. Quantification was performed with n = 5 random fields. H Flow cytometry of IFNγ expression in CD8⁺T cells co-cultured with BMDM or TAM treated with vehicle, LDL, or oxLDL ± SPP1 antibody. I, K Concentrations of indicated lipoproteins in human plasma (n = 16 patients) or human TIF (n = 12 patients) (I), and in mouse plasma or mouse TIF (n = 12 mice) (K). J, L Correlation between TIF oxLDL level and TREM2⁺SPP1⁺TAM proportion in human HCC tumors (n = 12) (J) and mouse HCC tumors (n = 12) (L). M PCA of the transcriptome of BMDM (n = 3 biological replicates) or TAM treated with vehicle (n = 3 biological replicates), LDL (n = 2 biological replicates), or oxLDL (n = 3 biological replicates). N GSEA of genes upregulated by oxLDL (log2 fold change > 1), on genes ranked by log2 fold change between TAM subsets versus other TAMs. Statistical P value was determined from 10,000 permutations. O Schematic of co-injection experiments. P Tumor volume of mock/oxLDL-treated TAM co-injection tumors (n = 6 mice). Q, R Flow cytometry of TREM2, SPP1 expression in TAMs (Q) and IFNγ expression in tumor-infiltrating CD8⁺T cells (R) (n = 6 mice). S Schematic of the sample collection and analysis workflow. T Heatmap depicts the BayesPrism-inferred fractions of indicated cancer cell subpopulations in 13 HCC samples. Hierarchical clustering shows that these 13 HCC samples can be classified into metabolism (8 samples) and stemness (5 samples) subtypes. U OxLDL concentrations (mean of n = 3 experimental replicates) in the TIF isolated from metabolism (n = 8) and stemness (n = 5) subtype HCC samples. V Flow cytometry of TREM2 and SPP1 expression in macrophages (mean of n = 3 biological replicates) treated with TIF (1:10) isolated from metabolism (n = 8) and stemness subtype (n = 5) HCC samples. Data represent the mean ± SD, n = 3 biological replicates in (C, E, F, H). Statistical significance was determined by a two-tailed unpaired t-test (C, E–I, K, P–R, U, V) and a two-tailed one-sample t-test (J, L). Schematics in O and S were created in BioRender. Chu, T. (2025) https://BioRender.com/r2v4jgs. Source data are provided as a Source Data file.