Table 2 Key events (KE) contained in AOP 173 (https://aopwiki.org/aops/173). Markers, cell types and assays were identified in Vietti et al., 2016 and Nymark et al., 2018. WP numbers refer to Wikipathways (https://www.wikipathways.org/index.php/WikiPathways). Relevance of the biomarkers for predicting lung fibrosis is described as A (association between in vitro and in vivo data for the biomarker), B (biomarker involved in the AO as demonstrated with deficient or transgenic mice, inhibitors, etc), C (biomarker strongly associated with the AO), D (biomarker identified by data mining). ELISA: enzyme-linked immunosorbent assays; EPR: electron paramagnetic resonance; GO: Gene Ontologies; qRT-PCR: quantitative reverse transcription-polymerase reaction; WB: western blot
KE # | KE | Biomarkers | Cell type | Assay | Relevance |
|---|---|---|---|---|---|
1495 | Interaction with the resident cell membrane components | Toll-like receptor signaling WP75 (CXCL8, CCL3, CCL4, CCL5) | Epithelial cells | Transcriptomics or individual assays (qRT-PCR) | D |
DAMPS/alarmins (IL-1a) | Macrophages | ELISA, qRT-PCR | C | ||
1496 | Secretion of proinflammatory and profibrotic mediators | ROS | Macrophages, fibroblasts | EPR (acellular), HO-1 (cellular, ELISA, RT-PCR) | C |
p38 MAPK | Fibroblasts | WB | C | ||
NF-KB | Macrophages | WB | C | ||
MAP kinase | Epithelial cells | WB | C | ||
IL-1b (+ NADPH oxidase and inflammasome) | Macrophages, epithelial cells | ELISA, WB (± NADPH oxidase or inflammasome inhibitors) | A, B, C | ||
TNF-a | Macrophages | ELISA, WB (qRT-PCR) | C | ||
IL-18 | Epithelial cells | ELISA, WB (qRT-PCR) | C | ||
IL-8 | Epithelial cells | ELISA, WB (qRT-PCR) | C | ||
TGF-b | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | B, C | ||
PDGF | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | C | ||
Cytokine and inflammatory response WP530 (PDGFA, CXCL2, CSF3, CSF2, IL12B, IL13, IL4, IL5, IL6) | Epithelial cells | Transcriptomics | D | ||
Chemokine signaling WP3929 (CCL2, CCL11, CCR2, CCR3) | Epithelial cells | Transcriptomics | D | ||
1497 | Recruitment of inflammatory cells | Â | Â | Â | Â |
1498 | Loss of alveolar capillary membrane integrity | Transepithelial/transendothelial electrical resistance (TEER) | Endothelial cells, epithelial cells | Ohmic resistance or impedance | C |
ROS | Macrophages, fibroblasts | EPR (acellular), HO-1 (cellular, ELISA, qRT-PCR) | C | ||
1499 | Activation of T (T) helper (h) type 2 cells | Chondrocyte differentiation WP474 (CTGF, TGFA, GREM1, ATP11A) | Epithelial cells | Transcriptomics | D |
Matrix metalloproteinases WP129 (MMP9, MMP2, TIMP1) | Epithelial cells | Transcriptomics | D | ||
TGFB signaling WP560 (SKIL, SPP1) | Epithelial cells | Transcriptomics | D | ||
Differentiation pathway WP2848 (EFG, IGF1, HGF, FGF1, FGF2, FGF7) | Epithelial cells | Transcriptomics | D | ||
Cytokine and inflammatory response WP530 (PDGFA, CXCL2, CSF3, CSF2, IL12B, IL13, IL4, IL5, IL6) | Epithelial cells | Transcriptomics | D | ||
Chemokine signaling WP3929 (CCL2, CCL11, CCR2, CCR3) | Epithelial cells | Transcriptomics | D | ||
Leukocyte/Myeloid cell differentiation GO: 0045637/GO: 1902105 (CALCA, CEBPB) | Epithelial cells | Transcriptomics | D | ||
TGF-b | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | B, C, D | ||
PDGF | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | C, D | ||
1500 | Fibroblast proliferation and myofibroblast differentiation | Smad | Fibroblasts, epithelial cells | WB | C |
ERK1/2 | Fibroblasts | WB | A | ||
fibroblast proliferation | Fibroblasts | cell count, cell viability assays | A | ||
fibroblast differentiation (a-SMA) | Fibroblasts | qRT-PCR, WB | C | ||
epithelial-mesenchymal transition, EMT (ZO-1, SP-C, E-Cad, fibronectin, FSP-1, a-SMA, vimentin) | Epithelial cells | qRT-PCR, WB | C | ||
MAPK signaling WP382 | Epithelial cells | Transcriptomics | D | ||
p38 MAPK WP400 | Epithelial cells | Transcriptomics | D | ||
TGFB signaling WP560 (SKIL, SPP1) | Epithelial cells | Transcriptomics | D | ||
TGF-b | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | B, C, D | ||
PDGF | Macrophages, fibroblasts, epithelial cells | ELISA, WB (qRT-PCR) | C, D | ||
Chondrocyte differentiation WP474 (CTGF, TGFA, GREM1, ATP11A) | Epithelial cells | Transcriptomics | D | ||
Differentiation pathway WP2848 (EFG, IGF1, HGF, FGF1, FGF2, FGF7) | Epithelial cells | Transcriptomics | D | ||
1501 | Extracellular matrix deposition | Collagen production (Collagen I and III or soluble collagen) | Fibroblasts | qRT-PCR, WB, Sircol assay | A |
1458 | Pulmonary fibrosis | Â | Â | Â | Â |