Fig. 4: S100A8/S100A9 inhibition reduces the fibrotic response to synthetic elastomers.

Discs made of PDMS with a diameter of 4 mm and a thickness of 1 mm were implanted SubQ on mouse backs. The tissue surrounding the implant was analyzed 24-hour (a–f) or 30-day (h–p) post-implantation. a, b Proteomic analysis of the protein lysates extracted from retrieved elastomers 24 h post-implantation, the various proteins on the surface of PDMS (a) and H90 (b) samples were sorted in descending order of protein mass spectrometry signal intensity (only the top 15 proteins with intensity were counted). The surface proportion of proteins with top 15 strength on PDMS (a) and H90 (b) is displayed in a circular graph. c Comparison of various protein intensities on the surfaces of PDMS and H90 (under the condition of ensuring equal total protein content). Proteomic analysis was run on one sample pool per treatment group (from n = 3 biological replicates). IHC was performed for S100A8 (staining shown in d, with quantification shown in e). Cells stained by the S100A8 marker show a brown color. Data were collected in the tissue within 50 μm from the tissue-material interface (n = 3 mice per group, mean ± s.d.). Scale bar = 50 μm. f qRT-PCR analysis of mRNA expression for S100a8 and S100a9 (n = 5 mice per group, mean ± s.d.). g RNA profile in macrophages cultured on H90 and PDMS elastomers ex vivo for three days (under P < 0.05). h The S100A9 inhibitor TAS (1 mg/kg or 3 mg/kg) was administered orally in drinking water to mice for 30 consecutive days with PDMS discs implanted four weeks previously. i, j Digital photos and M&T-stained histological sections of excised 4-week post-implantation in wild-type mice (thickness of the collagen capsule shown in j, n = 3 mice per group, mean ± s.d.). The asterisk sign “*“ in the section images denotes the original locations of the implants. Scale bar = 50 μm. k The construction and experimental overview of the S100A8-KO mice model. Created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license. l Digital photos and M&T-stained histological sections of excised 4-week post-implantation in S100A8-KO mice (thickness of the collagen capsule shown in m, n = 6 mice per group, mean ± s.d.). The asterisk sign “*“ in the section images denotes the original locations of the implants. Scale bar = 50 μm. n IHC was performed for FBR-related cell markers (α-SMA for fibroblasts and F4/80 for macrophages) (staining shown in n, with quantification shown in o). Cells stained by inflammatory markers show a brown color, while all nuclei stained with hematoxylin are blue. Data were collected in the tissue within 50 μm from the tissue-material interface (n = 5 mice per group, mean ± s.d.). p qRT-PCR analysis of mRNA expression for FBR-related genes in S100A8-KO mice (n = 6 mice per group, mean ± s.d.). Statistical significance was determined by one-way analysis of variance (ANOVA) with Bonferroni multiple comparison test (e, f, j, p) or unpaired, two-tailed t-test (m, o).