Fig 2: Binding of PPARγ in Ctss and Mmp12. ChIP assay in Raw 264.7 and 3T3-L1 undifferentiated cells treated with pioglitazone. a, b The schematic representation shows the location of primers flanking putative PPARγ-binding sites (grey rectangles) in Ctss and Mmp12. Sequences containing the potential PPARγ-binding sites in Ctss and Mmp12 loci were amplified by real-time polymerase chain reaction in (c, d) Raw 264.7 and (e, f) 3T3-L1 undifferentiated cells. Data were collected from three independent experiments

Fig 3: Effect of PPARγ activation on expression of Ctss and Mmp12. a Raw 264.7 cells, b peritoneal macrophages, c 3T3-L1 undifferentiated cells, d 3T3-L1 differentiated cells, and e A7r5 cells were treated with various concentrations of pioglitazone for 20 h. Expression of Ctss and Mmp12 relative to the average expression of non-treatment control group. Data were collected from two independent experiments. *P < 0.05, **P < 0.01, and ***P < 0.001

Fig 4: Expression and location of elastolytic enzymes in the aorta and PVAT. Expression of genes for cathepsins and MMPs in the a aorta (n = 7, 5, and 6 for control, ob/ob, and ob/ob + Piog groups respectively) and b PVAT (n = 3, 5, and 6 for control, ob/ob, ob/ob + Piog groups respectively). mRNA amount is expressed relative to the average expression in control mice. *P < 0.05, **P < 0.01, and ***P < 0.001. ND, not detectable. c Immunofluorescence staining for CTSS (green), MMP-12 (red) and F4/80 (blue) in the thoracic aorta and PVAT. The DAPI nuclear counterstain appears light blue. Magnification of the square in (c) is shown in (d). The while arrow indicates the location of elastic fiber break with increased signals of MMP-12 and F4/80. e Plasma levels of CTSS, MMP-12, and MCP-1 by ELISA (n = 7, 5, and 6 for control, ob/ob, and ob/ob + Piog groups respectively). All data are resulted from 3-month-old male mice. Original magnification × 400 for (c) and × 1200 for (d)

Fig 5: HET3 inflammatory profiling and lung damage assessment following CS exposure: Similar to the previously mentioned mouse model groups, we also collected BALF and lung tissues from HET3 mice post exposure for various analysis, including total cell count and immune cell count to assess inflammatory markers and immune cell infiltration. The lung tissue from these mice groups were further utilized for ELISA, IHC, and H&E staining to assess the tissue architecture changes, macrophages infiltration, MMP9/12 levels. (a) Total cell count/mL of BALF, (b) Percentage Macrophage (c) percentage neutrophil count in the BALF of CS‐exposed HET3 mice after 7 days. (d) Total count of CD68+ cells post‐IHC analysis in air‐ and CS‐exposed groups. Bar graphs of ELISA results for (e) MMP9 and (f) MMP12 levels. (g) H&E images illustrating lung tissue architecture in air‐control and CS‐exposed mice. (h) IHC staining of lung tissue highlighting CD68+ cells (marked with red arrowheads). N = 3–5/group, Student's t‐test was utilized for the analysis. The value of significance was given as: Mean ± SEM. **p < 0.01, ***p < 0.001, ****p < 0.0001 ns: Non‐significant.