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. 2023 Aug 21;11(8):e007441. doi: 10.1136/jitc-2023-007441

Figure 5.

Figure 5

FABP5 regulates the immunosuppressive activities of C1q+ TAMs. TAMs were sorted from human MPE and were treated with 100 µM SBFI-26 (an FABP5 inhibitor) or 0.1% DMSO for 72 hours. (A) Fatty acid accumulation was assessed by BODIPY 493/503 stain using flow cytometry (n=7). (B) The protein expression level of PPAR-γ in TAMs from human MPE was measured by western blotting. (C) The relative expression levels of TREM2, Tim-3, SIRPα, PD-1 and PD-L1 genes in TAMs from human MPE were measured by qRCR (n=4). (D and E) Immune inhibitory molecules (TREM2, Tim-3, SIRPα, PD-1, PD-L1) in C1q+ TAMs were detected by flow cytometry (n=4–7). (F and G) M2-like markers (CD163, CD206, CX3CR1) in C1q+ TAMs were detected by flow cytometry (n=4–5). (H and I) The expression of IL-10 and TGF-β were detected by flow cytometry (n=3–4). (J−L) CD8+ T cells were isolated from peripheral blood of healthy donors and co-cultured with C1q+ TAMs of human MPE treated with SBFI-26 or DMSO for 72 hours. The tumor-killing activities (J), exhaustion‐related molecules (K), and proliferation (L) of CD8+ T cells were assessed by flow cytometry (n=3). Data shown in (A−L) are representative of at least three independent experiments (mean±SD). Statistical analysis was performed using unpaired two-tailed Student’s t-test. *p<0.05, **p<0.01, ***p<0.001. C1q, component 1q; CX3CR1, C-X3-C motif chemokine receptor 1; DMSO, Dimethyl sulfoxide; IFN, interferon; IL, interleukin; FABP5, fatty acid binding protein 5; GAPDH, Glyceraldehyde-3-phosphate dehydrogenase; MFI, mean fluorescent intensity; MPE, malignant pleural effusion; mRNA, messenger RNA; PD-1, programmed cell death-1; PD-L1, programmed cell death-ligand 1; PPAR-γ, peroxisome proliferator-activated receptor-γ; qPCR, quantitative PCR; SIRPα, signal regulatory protein α; TAM, tumor-associated macrophage; TGF-β, transforming growth factor β; TIGIT, T cell immunoglobulin and ITIM domains; Tim-3, T-cell immunoglobulin-3; TNF, tumor necrosis factor; TREM2, triggering receptor expressed by myeloid cells-2.