Fig 1.
Schematic diagram showing the role of the gut–aorta axis in PM2.5 injury.
SMC, smooth muscle cell. LPS, Lipopolysaccharides. PM2.5, Particulate matter 2.5.
Fig 2.
PM2.5 exposure induces dose-dependent aortic injury characterized by inflammatory infiltration and structural disruption. A. Representative images of HE staining and the percentage of inflammatory cell infiltration in the aorta of mice treated with saline, low-dose PM2.5 (2 mg/kg), or high-dose PM2.5 (4 mg/kg) (n = 6).
Arrows indicate areas of inflammatory cell infiltration. Scale bars represent 200 μm and 50 μm. B. Representative images of aorta sections stained with EVG and Elastin break grades were analyzed (n = 6). Arrows indicate sites of elastic fiber layer disruption. Scale bars represent 200 μm and 50 μm. C. Representative images of aorta sections stained with Masson and the collagen expression level was analyzed (n = 6). Arrows indicate areas of collagen deposition. Scale bars represent 200 μm and 50 μm. D. Representative images and analysis of aorta sections labeled with antibodies against Ly6G (green) and CD68 (red), with nuclei stained using DAPI (blue) (n = 6). Scale bars represent 50 μm. Quantification graphs on the left and right represent the statistical results for Ly6G and CD68, respectively. *p < 0.05, **p < 0.01, and ***p < 0.001, data are presented as the mean ± SD, one-way ANOVA, Tukey’s multiple comparison test.
Fig 3.
Bioinformatic analysis identifies potential mechanisms and key pathways in PM2.5-induced aortic injury and inflammation. A. Venn diagrams of PM2.5, aortic vascular smooth muscle, aortic endothelium, inflammation of the aorta, related genes from Genecards.
B. GO pathway enrichment analysis of the shared genes across different groups was performed using Metascape. C. KEGG pathway enrichment analysis of the common gene by R. Pathways are ordered by -log₁₀(p-value) from highest to lowest. D-F. GO pathway enrichment analysis by R (Cellular Component, Biological Process, Molecular Function). For panels D, E, and F, terms are ordered by p-value in ascending order from top to bottom.
Fig 4.
PM2.5 exposure elevates circulating inflammatory cytokines and immune cells in mice. A. Schematic of the experimental design in this study.
B. ELISA assessment of inflammatory cytokines TNF-α, IL-1β, IL-6, and CCL2 in murine serum across various groups (n = 6). C. Gating strategy for identification of monocytes and neutrophils in mouse blood. LY6Chigh monocytes were identified as CD45+CD115+GR1+ and LY6Clow monocytes were identified as CD45+CD115+GR1-, neutrophils were identified as CD45+CD115-GR1+ . D. Representative flow cytometry analysis of circulating blood neutrophils, LY6Chigh and LY6Clow monocytes in saline-, PM2.5 lo- and PM2.5 high-treated mice. E. Flow cytometry data were analyzed as depicted (n = 6). *p < 0.05, **p < 0.01, and ***p < 0.001, data are presented as the mean ± SD, one-way ANOVA, Tukey’s multiple comparison test.
Fig 5.
PM2.5 exposure compromises the intestinal barrier and increases circulating lipopolysaccharide. A. ELISA analysis of LPS in murine serum at the endpoint (n = 6).
B and C. Gross morphology of the gastrointestinal tract from saline-, low dose of PM2.5 – and high dose of PM2.5 – treated mice (n = 6). D. Representative TEM image of sections from the intestinal epithelium of different groups. E. Representative HE images of intestine of saline-, low dose of PM2.5 – and high dose of PM2.5 – treated mice. F. Intestinal injury evaluation through HE staining of the intestine, presented as Chiu scores (n = 6). G and H. Protein expression levels of occludin and claudin 1 (n = 3). I. Representative immunofluorescence images of occludin and claudin 1 in the intestine of Saline-, low dose of PM2.5 – and high dose of PM2.5 – treated mice. Scale bar = 50 μm. J. Quantification of fluorescence intensity in (I) (n = 6). *p < 0.05, **p < 0.01, and ***p < 0.001, data are presented as the mean ± SD, one-way ANOVA, Tukey’s multiple comparison test.