TRAIL signals through the ubiquitin ligase MID1 to promote pulmonary fibrosis

Figures

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  Fig. 1. Lung and alveolar structure is disrupted, and inflammatory responses occur in IPF. Representative images of haematoxylin and eosin stained transbronchial biopsy sections at 200x magnification with arrows highlighting described features: Normal lung architecture from control patients (a), distortion of the normal lung architecture and obliteration of alveolar architecture consistent with IPF (b), hyperplasic pneumocytes (c), inflammatory infiltrates (d), and fibroblastic proliferation (e, f). Representative high-sresolution computerised-tomography image showing areas of air-space consolidation, ground glass opacities, small nodular opacities and bronchial wall thickening and dilatation (g)

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  Fig. 2. Serum from IPF patients had elevated levels of TRAIL (a) and lung biopsies elevated MID1 (b) protein, which corresponded with a trend towards decreased activity of PP2A (c) when compared to those from control subjects. The percentage predicted diffusing lung capacity for carbon monoxide (DLco) did not have a strong inverse association with serum TRAIL (d) but was inversely associated with MID1 protein (e) and correlated with the levels of PP2A activity (f) in lung biopsies from IPF patients. n = 8, * p < 0.05

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  Fig. 3. Wild-type mice treated with the PP2A activator AAL(s) and Tnfsf10−/− mice were protected from increases in Mid1 mRNA, and the loss of PP2A activity and lung function induced by bleomycin. Mid-1 mRNA was downregulated in AAL(s) treated WT mice and Tnfsf10−/− mice exposed to bleomycin (a) while PP2A activity was increased (b). The vital capacity (VC) and pressure at the peak of compliance (Cpk) were both decreased by bleomycin 21 days post exposure but Tnfsf10−/− mice or those treated with AAL(s) were protected (c-d). n = 5–8, * p < 0.05

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  Fig. 4. Wild type mice treated with AAL(s) and Tnfsf10−/− mice had reduced expression of collagen-α2(I) (a), TGFβ (b), mmp9 (c) and ccl2 (d) in their lungs 21 days after bleomycin exposure. n = 7–12, * p < 0.05

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  Fig. 5. AAL(s) treated wild type mice and Tnfsf10−/− mice were protected from bleomycin-induced collagen deposition and apoptosis. Collagen deposition in Masson’s trichrome stained lung sections (a). Images at 200x magnification of representative sections from Masson’s trichrome for (b) Wild Type saline and (c) bleomycin treated (d) wildtype bleomycin treated with AAL(s), (e) TRAIL−/− bleomycin treated and (f) TRAIL −/− saline. Apoptosis in terms of the percentage of TUNEL positive cells in lung sections (g), which peaked at one day post bleomycin but was still significantly elevated after day 21(h). n = 6, * p < 0.05

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  Fig. 6. rTRAIL stimulated Mid1 and collagen- α2(I) production in isolated primary mouse fibroblasts. Mid1 (a) and collagen-α2(I) (b) expression per copy of HPRT in cultured fibroblasts. n = 3 independent experiments * p < 0.05