Influence of CM of M1 polarized, M2 polarized or unstimulated macrophages on extracellular matrix deposition by fibroblasts. After 144 h, HDFs stimulated with CM of M1 macrophages showed reduced COL1A1 and COL3A1 gene expression levels compared to stimulation with CM of M2 and unstimulated macrophages (A). No differences in COL1A1 deposition by fibroblasts were seen after the three different stimulations after 72 h. However, less collagen type I protein deposition was seen in fibroblasts stimulated with CM of M1 macrophages compared to stimulation with CM of unstimulated macrophages after 144 h (B). ** p < 0.01, Difference between HDFs stimulated with CM of M1 polarized and CM of M2 polarized macrophages. ## p < 0.01, Difference between HDFs stimulated with CM of M1 polarized and CM of unstimulated macrophages. Gene expression analysis data were analyzed using two-way ANOVA followed by Bonferroni’s post-test, n = 4. COL1A1 protein expression was shown in red, nuclei in blue (DAPI) and original magnification was 200×.