Fig 2: TL1A levels are increased after TGF-β1 treatment in bronchial epithelial cells.(A) Volcano plots were constructed using fold-change values and adjusted P. The red point in the plot represents overexpressed mRNAs and the blue point indicates down-regulated mRNAs with statistical significance. (B) The expression distribution of TNFSF15, where different colors represent different groups and the vertical axis represents the gene expression distribution. (C and D) Protein expression levels of E-cadherin, N-cadherin, fibronectin, DR3, TL1A, and α-SMA after treatment with different concentrations of TGF-β1 for 48 hours. (E) Immunofluorescence for collagen I, fibronectin, and TL1A after treatment with 20 ng/mL TGF-β1 for 48 hours. (F) The RNA levels of E-cadherin, collagen I, N-cadherin, fibronectin, DR3, TL1A, MMP-9. and α-SMA after treatment with different concentrations of TGF-β1 for 48 hours. (G-H) The levels of secreted TL1A remained unchanged in BEAS-2B cells treated with TGF-β1 at various concentrations and during various time courses. Data are expressed as means ± standard deviation.TGF, transforming growth factor; TL1A, tumor necrosis factor ligand-related molecule 1A; DR3, death receptor 3; MMP-9, matrix metallopeptidase 9; α-SMA, α-smooth muscle actin; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.*P < 0.05, **P < 0.01 versus the control group.

Fig 3: Effects of TL1A/DR3 axis inactivation on EMT and remodeling indicators in bronchial epithelial cells.(A) mRNA expression levels of TL1A after small interference RNA transfection. (B-D) Protein and mRNA expressions of fibronectin, collagen I, N-cadherin and TL1A after different treatments. (E-G) mRNA expression levels of DR3 after small interference RNA transfection. (H-J) Protein and mRNA expression of fibronectin, collagen I, N-cadherin, and DR3 after different treatments. Data are expressed as mean ± standard deviation.TL1A, tumor necrosis factor ligand-related molecule 1A; DR3, death receptor 3; EMT, epithelial-mesenchymal transition; ns, not significant; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.*P < 0.05, **P < 0.01 versus the corresponding group.

Fig 4: Intratracheal administration of TL1A in the OVA-challenged mice.(A-D) H&E and Masson staining were used to observe histopathological changes after TL1A treatment in the mouse model of asthma. Histopathological lesions were analyzed quantitatively. (E-G) Protein expression of fibrosis indicator (collagen I and α-SMA) after treatment and subsequent quantitative analysis. (H-I) Immunofluorescence detection of fibrosis “indicator” proteins and their quantitative analyses. (J) Expression of IL-4, IL-5, and IL-13 in the blood detected by ELISA. (K) AHR was measured by airway reactivity to increased doses of inhaled methacholine treatment. Administration of TL1A can increase methacholine-induced AHR.TL1A, tumor necrosis factor ligand-related molecule 1A; OVA, ovalbumin; H&E, hematoxylin and eosin; α-SMA, α-smooth muscle actin; IL, interleukin; AHR, airway hyper-responsiveness; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.*P < 0.05, **P < 0.01.

Fig 5: TL1A knockout effectively relieves OVA-induced airway inflammation and remodeling in mice.(A) Following quantitative analysis, H&E and Masson staining were used to evaluate histopathological changes in the TNFSF15 WT and knockout mouse model. (B) Immunofluorescence detection of fibrosis “indicator” proteins (α-SMA and collagen I) and their quantitative analysis. (C) Volcano plot was used to present the results of RNA-seq from OVA-treated lung tissues between TNFSF15 WT and knockout mice (differential genes were determined using a P value of ≤ 0.05 and a |FC| > 1.2). (D and E) Bubble and circular maps of KEGG pathway enrichment.TL1A, tumor necrosis factor ligand-related molecule 1A; OVA, ovalbumin; H&E, hematoxylin and eosin; WT, wild-type; α-SMA, α-smooth muscle actin; FC, fold-change.*P < 0.05, **P < 0.01.