Journal: Frontiers in Immunology
Article Title: CD14 + CD16 + monocyte-derived TREM2 macrophages promote lung fibrosis in systemic sclerosis–interstitial lung disease
doi: 10.3389/fimmu.2026.1748574
Figure Lengend Snippet: GM-CSF-induced CD14 + CD16 + monocyte-derived macrophages promoted fibrotic activation of lung fibroblasts, an effect depends upon TREM2 expression. (A) Volcano plot showing DEG in fibroblasts from SScLO compared to those from HCs ( GSE128169 ). Fibrotic activation genes, including POSTN , COL1A1 , COL3A1 , COL4A1 , COL5A1 , COL8A1 , TGFBI , and ACTA2 , were significantly upregulated in SScLO fibroblasts. (B) Schematic diagram of the co-culture experimental design. Monocytes (CD14 + CD16 - or CD14 + CD16 + ) were differentiated into macrophages using GM-CSF for 7 days, then co-cultured with human lung fibroblasts for 5 days with or without TREM2 inhibitor. Bulk RNA sequencing and western blot analyses were performed to assess gene expression and protein levels, respectively. (C) Volcano plots showing DEG in fibroblasts co-cultured with CD14 + CD16 - vs. CD14 + CD16 + macrophages (left) and CD14 + CD16 + macrophages with or without TREM2 inhibitor (right). All macrophages were derived from SSc-ILD patients. Co-culture with CD14 + CD16 + macrophages induced fibrotic gene expression ( POSTN , COL7A1 , ACTA2 , and TGFBI ), which was significantly reduced by TREM2 inhibition. Upregulated genes are shown in red (FC > 2, adj. p < 0.05), downregulated in blue (FC < -2, adj. p < 0.05), and non-significant genes in black. Dotted lines indicate statistical thresholds. (D) Representative western blot images of COL7A1 (34 kDa), COL3A1 (200 kDa), COL1A1 (220 kDa), and α-SMA (42 kDa); GAPDH (37 kDa) was used as a loading control. Conditions with TREM2 inhibitor are indicated in red. (E–H) Quantification of protein levels normalized to GAPDH: (E) COL7A1, (F) COL3A1, (G) COL1A1, and (H) α-SMA. Expression of COL7A1, COL1A1, and α-SMA was significantly elevated in fibroblasts co-cultured with CD14 + CD16 + monocytes derived macrophages from SSc-ILD compared to HCs and CD14 + CD16 - monocytes derived macrophages from SSc-ILD. COL3A1 expression was also elevated in SSc-ILD fibroblasts compared to HCs. TREM2 inhibition markedly reduced expression of all fibrotic markers. Statistical analysis was conducted using MANOVA, followed by Tukey’s post-hoc multiple comparisons test. Data are presented as mean ± SEM, with n = 6 per group. Statistical significance is indicated as * p < 0.05, ** p < 0.01 for comparisons between SSc-ILD and HCs within the same subset; # p < 0.05, ## p < 0.01 for comparisons between CD14 + CD16 - and CD14 + CD16 + subsets within SSc-ILD patients; $ p < 0.05, $$ p < 0.01 for comparisons between SSc-ILD and TREM2 inhibitor within the same subset.
Article Snippet: Macrophages differentiated from monocyte subsets by GM-CSF from SSc-ILD patients were cultured for 7 days and subsequently co-cultured with commercially sourced human lung fibroblasts (ACBR 469, Cell Systems, Kirkland, WA, USA) for 5 days, with or without treatment with a TREM2 inhibitor (BLP-NR018, Alomone Labs, Jerusalem, Israel).
Techniques: Derivative Assay, Activation Assay, Expressing, Co-Culture Assay, Cell Culture, RNA Sequencing, Western Blot, Gene Expression, Inhibition, Control