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Background: Extensive studies have suggested epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transformation (FMT) as major drivers of fibrosis. Both EMT and FMT are strongly regulated by TGFβ1. Objectives. The aim of this study was to assess a specific transcriptional analysis of a selected panel of genes involved in fibrogenesis by profiling TGFβ-stimulated human lung fibroblasts (HLFs) and human bronchial epithelial cells (HBECs) derived from IPF patients and healthy donors. Moreover, the effects of Nintedanib and the ALK5 inhibitor, SB525334, were evaluated. Methods: Cultured primary HLFs and HBECs were stimulated with TGF-β1 (1.25 and 5 ng/ml, respectively). IPF-derived cells were exposed to Nintedanib (3 µM) and SB525334 (1 µM). RNA was extracted and subsequently reverse transcribed and amplified. RT2 Profiler™ PCR Arrays Human Fibrosis (Qiagen) were used to gene expression analysis. Results: Approximately half of the assessed genes were endowed with a differential expression (≥1.5 fold) between non-stimulated IPF and control HLFs (e.g. GREM1, HGF) and HBECs (e.g. ITGB3, ENG). The above expression pattern was further modified when TGF-β1 was applied to IPF and control cells. Both Nintedanib and SB525334 mainly induced a significant effect on TGFβ1-induced differential expression of genes related to extracellular matrix remodelling (e.g. COL1A1 and COL3A1). Conclusions: Our study revealed a basal differential expression of a selected panel of genes among control and IPF cells. Furthermore, the subsequent validation step with Nintedanib may provide insights on new targets endowed with a potential anti-fibrotic effect.

Background: Evaluation of fibrosis and its severity is the commonest parameter to screen potential new medicines in rodents treated with bleomycin (BLM). Results are mainly reported by histological analysis and indirect measurement of collagen through hydroxyproline (HYP) quantification. Objectives: In the present study we performed a comparative analysis of different methods to assess collagens induced by BLM in the mouse lung. Methods: BLM (0.02 U/kg) was administered by oropharyngeal aspiration to male C57BL/6 mice on day 0 and day 4. Oral Nintedanib (60 mg/kg/day) started from day 7. Three and four weeks after the first BLM administration, histopathological examination and collagen genes expression analysis were applied. Moreover, HYP and collagen isoforms (LC-MS) quantification in lung homogenates were assessed. Results: Ashcroft score and automated measure of lung fibrosis revealed significant fibrotic lesions in BLM-treated animals. Specific collagen genes appeared up-regulated in BLM group. LC-MS quantification of collagen isoforms correlated with HYP levels although, interestingly, showed a higher therapeutic window between control and BLM group (1.5 vs. 0.5 fold, respectively). Nintedanib significantly affected all the evaluated readouts. Conclusions: Our study provides a comprehensive analysis of changes in collagen genes and proteins following BLM treatment in mice and the effect of Nintedanib. Importantly, our data indicate for the first time LC-MS as a sensitive and reliable method for collagen quantification in lung homogenate. This approach might implement the most employed HYP assay to achieve reliable predictions of efficacy for therapeutics in lung fibrosis.

Background & Objectives: The aim of this study was to investigate the time-course of the molecular and histological changes induced by a double intratracheal (IT) administration of bleomycin (BLM) on lung tissue. Methods: Male SD rats were injected with BLM (2 U/kg, IT) or saline on day 0 and day 4 and sacrificed at day 7, 14, 21, 28 and 56 after BLM first dose. Several inflammatory and fibrotic biomarkers were assessed in lung, BALF and plasma by colorimetric or immunometric assays. Histomorphometric analysis of lung fibrosis was performed on Masson’s trichrome stained sections. Results & Conclusions: In lungs of BLM-treated animals, several ECM proteins were significantly increased at day 7 (30-, 40- and 80-fold increase for TIMP1, PAI-1 and SPP1, respectively), and progressively declined over time, reaching control values at day 56. A significant increase in lung hydroxyproline levels was evident starting from day 14 (2.4-fold increase) and was maintained over the duration of the study. Histomorphometric evaluation revealed a sustained fibrosis during the first three weeks (fibrotic area: 50%), followed by a progressive reduction at day 28 and 56 (30%). Overall, these results indicate that the most suitable time point for assessing lung fibrosis and its targeted interventions is between 21 and 28 days post-BLM, where the fibrotic response appears to be more stable and consistent. Additional investigations, including transcriptomic and proteomic approaches will be essential to obtain a more comprehensive characterisation of the present model.

Background: Idiopathic Pulmonary Fibrosis (IPF), is a progressive lung disease characterized by basal and subpleural fibrosis associated with honeycomb changes. In experimental settings, single intratracheal (IT) administration of bleomycin (BLM) to rodents is the most commonly used model. In order to more closely mimic human IPF, a novel experimental procedure with two IT administrations of BLM in rats is described. Aims and objectives: Histological and biomolecular findings following single and double IT administration of BLM in the rat were compared. Furthermore, the effect of Nintedanib was assessed. Methods: Single (4U/Kg, day 1) or double (2 X 2U/Kg, day 1 and day 4) administration of BLM was given IT to male SD rats. Nintedanib (100 mg/kg, oral) was administered once daily for three weeks starting from day 7. Morphometric quantification of different patterns of lung fibrosis and cluster gene expression on tissue homogenate (Real Time PCR) were performed. Results: A single BLM administration induced focal collagen deposition mostly surrounding the main bronchi. In contrast, two BLM administrations seemed to evoke a more diffuse pattern of interstitial collagen deposition widening lung parenchyma. Reduction of lung fibrosis by Nintedanib was more effective in the 2 X 2U/Kg group (~46%) compared to 4U/Kg group (~11%). Moreover, normalisation by Nintedanib of differentially modulated IPF-associated genes was more evident in 2 X 2U/Kg group. Conclusions: Our study provides a novel improved BLM rat model of IPF that is sensitive to the effect of Nintedanib and functional to assess efficacy in drug development.

Background: In the last 10 years, advanced molecular biology approaches and profiling techniques have greatly contributed to identify key regulatory molecules and pathways involved in several pathological states. IPF is a relatively poorly understood chronic and progressive disease and much of the information regarding the involved etiopathogenetic mechanisms was generated in the rodent bleomycin (BLM) model. A comprehensive multidisciplinary approach is proposed here to study molecular alterations in the lungs of BLM-treated rats and to improve the predictive nature of this model. Aims and objectives: We established proteomic and genomic survey approaches to monitor molecular changes induced by BLM in the rat airways and the therapeutic effect by Nintedanib. Methods: Male SD rats were intratracheally injected with a single administration of BLM (4U/Kg). Nintedanib (100 mg/kg, oral) was administered once daily for three weeks starting 7 days after BLM administration. Proteomic and gene expression analysis (Real Time PCR) were assessed in BALFs and lung homogenates. Levels of some targeted proteins were also monitored by ELISA specific assays. Results and Conclusions: The results highlight the peculiar features of BALFs and lung homogenates for the comprehensive molecular profiling of the rat BLM model. Investigation of a set of signalling transduction pathways altered in the BLM model and affected by Nintedanib is disclosed. Perspectives on targeted monitoring of novel markers of lung fibrosis are also discussed for a better understanding of the molecular pathogenesis of IPF and the response to therapy. VP and BP equally contributed.