Burgess, Janette K.

Abstract Introduction Pulmonary fibrosis is characterized by excessive fibroblast activation and alveolar remodeling, leading to progressive lung dysfunction. Osteoglycin (OGN), a small leucine-rich proteoglycan, and its functional fragment MC002 have been identified as regulators of alveolar epithelial regeneration, a process that is impaired in fibrotic lung disease. This study investigates the effects of OGN and MC002 on TGF-β-induced fibrotic responses in lung fibroblasts, organoids, and an in vivo fibrosis model. Methods Human lung fibroblasts (MRC5) were treated with OGN or MC002 for 48 hours, with or without transforming growth factor-beta (TGF-β; 2 ng/mL). Expression of the myofibroblast marker α-smooth muscle actin (ACTA2) and matrix markers collagen 1a1 (COL1A1) and fibronectin (FN1) was assessed by RT-PCR and Western blotting. Global transcriptomic changes were analyzed by RNA sequencing. Myofibroblast differentiation was evaluated by phalloidin staining and quantified using the phalloidin/DAPI ratio. Murine lung organoids were generated by co-culturing epithelial progenitor cells with fibroblasts and treated with TGF-β (2 ng/mL) in the presence or absence of OGN or MC002. Organoid number, size, and alveolar differentiation were quantified after 14 days. In vivo, pulmonary fibrosis was induced in mice using intratracheal bleomycin. MC002 was administered at different doses (6.75 µg or 20.25 µg) every other day starting from day 7 post-bleomycin, and lung weight and pressure-volume (PV) loops were assessed to evaluate fibrotic burden and lung mechanics. Osteoglycin expression in human lung tissue from 13 non-smokers, 11 ex-smokers, and 12 IPF patients was analyzed by immunostaining. Results TGF-β induced pro-fibrotic gene expression in fibroblasts, while OGN and MC002 alone had no pro-fibrotic effects. MC002 fully reversed TGF-β-induced ACTA2, COL1A1, and FN1 expression, whereas OGN selectively attenuated COL1A1. RNA-sequencing revealed broad suppression of fibrosis- and ECM-associated gene programs by MC002. At the protein level, TGF-β-induced ACTA2 expression was reversed by MC002 but not by OGN. Both compounds reduced TGF-β-induced stress fiber formation. In lung organoids, TGF-β impaired organoid formation and alveolar differentiation, effects that were restored by OGN and MC002 in a concentration-dependent manner. In the bleomycin model, MC002 significantly reduced lung weight and improved PV loop profiles, indicating attenuation of fibrotic stiffening and improved lung compliance. Osteoglycin protein expression was significantly diminished in IPF whole lung tissue and parenchyma compared to controls. Conclusion OGN, and particularly MC002, counteract TGF-β-driven fibroblast activation and myofibroblast differentiation while promoting alveolar preservation. The superior efficacy of MC002 supports its potential as a therapeutic candidate for pulmonary fibrosis. This abstract is funded by: Lung Foundation Netherlands 10.1.23.021PPS

Abstract As an intrinsically mechanosensitive organ, the lung experiences a range of mechanical forces. Chronic obstructive pulmonary disease (COPD) involves abnormal macroscopic cellular and extracellular matrix (ECM) changes that impact mechanical properties of the lung. Mechanosensitive Piezo1/2 channels are expressed in the lung including on airway smooth muscle cells (ASM) that mediate cellular responses to stretch and ECM biomechanics. The expression and roles of Piezos in COPD lung ASM are not known. We hypothesized that Piezo expression and activation are altered in COPD lung ASM influencing ECM regulation. Distribution of Piezo proteins in ASM and epithelium of small airways of COPD stage II and IV vs. non-COPD controls was assessed using immunohistochemistry and ImageJ (n=10-17/group). Isolated ASM cells from control (n=6) vs. COPD stage II and IV patients (n=3 each stage) were exposed to stretch or the Piezo1 agonist Yoda1 followed by measurement of ECM gene and protein expression. Less Piezo2 staining was observed in COPD IV patients compared to controls, with lesser area and intensity of staining in the epithelial layer, and lower intensity of staining in ASM and small airways as a whole. Fura-2-based imaging of ASM Ca 2+ showed lower influx after Yoda1 exposure in COPD II compared to control and COPD IV. Gene expression of Piezo1 increased upon stretching in controls but not in COPD ASM, while Piezo2 protein expression decreased with stretching in all groups. Yoda1 treatment resulted in decreased collagen1 , fibulin1 and periostin gene and collagen 1 and periostin protein expression in ASM. Overall, these results support a role for Piezo activation in abnormal ECM-ASM cell crosstalk in COPD.

Our study identified chronic obstructive pulmonary disease (COPD)-associated differences in the lung extracellular matrix (ECM) composition. We highlight the compartmental differences in the ECM landscape in different subtypes of COPD. The most prominent differences were observed for severe-early onset COPD. Moreover, we identified unique ECM signatures that describe airway walls and parenchyma providing insight into the intertwined nature and complexity of ECM changes in COPD that together drive ECM remodeling and may contribute to disease pathogenesis.

Repair and regeneration of a diseased lung using stem cells or bioengineered tissues is an exciting therapeutic approach for a variety of lung diseases and critical illnesses. Over the past decade, increasing evidence from preclinical models suggests that mesenchymal stromal cells, which are not normally resident in the lung, can be used to modulate immune responses after injury, but there have been challenges in translating these promising findings to the clinic. In parallel, there has been a surge in bioengineering studies investigating the use of artificial and acellular lung matrices as scaffolds for three-dimensional lung or airway regeneration, with some recent attempts of transplantation in large animal models. The combination of these studies with those involving stem cells, induced pluripotent stem cell derivatives, and/or cell therapies is a promising and rapidly developing research area. These studies have been further paralleled by significant increases in our understanding of the molecular and cellular events by which endogenous lung stem and/or progenitor cells arise during lung development and participate in normal and pathological remodeling after lung injury. For the 2023 Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases Conference, scientific symposia were chosen to reflect the most cutting-edge advances in these fields. Sessions focused on the integration of “omics” technologies with function, the influence of immune cells on regeneration, and the role of the extracellular matrix in regeneration. The necessity for basic science studies to enhance fundamental understanding of lung regeneration and to design innovative translational studies was reinforced throughout the conference.

The current study establishes functional links between endoplasmic reticulum (ER) stress and cellular senescence per se in the specific context of aging human lung fibroblasts. Recognizing that the process of aging per se is complex, modulated by the myriad of lifelong and environmental exposures, it is striking to note that chronic ER stress may play a crucial role in the establishment and maintenance of cellular senescence in lung fibroblasts.

We identified seven age-associated extracellular matrix (ECM) proteins, i.e., COL1A1, COL6A1, COL6A2 COL14A1, FBLN2, LTBP4, and LUM with higher transcript and protein levels in human lung tissue with age. Extensive immunohistochemical analysis revealed significant age-associated differences for COL6A2 in whole tissue, parenchyma, airway wall, and vessel, for COL14A1 and LUM in bronchial epithelium, and COL1A1 in parenchyma. Our findings lay a new foundation for the investigation of ECM differences in age-associated chronic lung diseases.

Beyond the structural changes, features including the dysregulation of endoplasmic reticulum (ER) stress response and increased senescence characterize the lung aging. ER stress response and senescence have been reported to be induced by factors like cigarette smoke. Therefore, deciphering the mechanisms underlying ER and senescent pathways interaction has become a challenge. In this review we highlight the known and unknown regarding ER stress response and senescence and their cross talk in aged lung.