Biology subjects

Burgess, J. K.

Publications and source records attributed to Burgess, J. K..

At least 19 recordsLinked to original sources

bioRxiv2026

Feasibility of adopting water displacement and 3D scanning methods to quantify lung volume reduction in ex vivo models

Lung volume reduction is a treatment for chronic obstructive pulmonary disease (COPD) patients with severe emphysema. Currently, in vivo animal models are used as a first step to quantify the efficiency of novel lung volume reduction treatments. By quantifying lung volume reduction in ex vivo samples, animal testing may be reduced. This study proposes two new methods for quantifying lung volume reduction in ex vivo tissue: water displacement and three-dimensional (3D) scanning. Porcine lung lobes were inflated and treated with cyanoacrylate glue to simulate lung volume reduction. Volume changes were measured using a custom water displacement setup and in a ventilated setting using a handheld Artec Space Spider 3D surface scanner. Both techniques detected post-treatment volume reductions. Water displacement offers a simple, cost-effective approach for isolated lung lobes, while 3D scanning enables volumetric analysis of intact lungs under ventilated conditions. These methods provide a reliable intermediate step between in vitro and in vivo testing, reducing animal use and improving preclinical assessment of novel lung volume altering interventions.

bioengineering↗

bioRxiv2026

Mechanosensitive Piezo Channels Contribute to Airway Changes in Chronic Obstructive Pulmonary Disease

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 Ca2+ 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.

physiology↗

bioRxiv2026

Differential collagen crosslinking and network organization creates distinct tissue remodeling patterns in fibrosis and COPD

Collagens are key components of the extracellular matrix (ECM) that play a crucial role in maintaining structure, strength, and function of the lungs. Fibrillar collagens are crosslinked by enzymes such as lysyl oxidases and transglutaminases and organized into networks by proteoglycans and glycoproteins. Collagens are the main load-bearing components and along with elastin may impart a non-linear strain hardening behavior to the lung. In disease, collagen crosslinking and organization can be disrupted, possibly due to abnormal levels of enzymes or ECM components. Few studies have examined collagen crosslinking and organization in healthy and diseased human lungs. In this study, alterations in collagen crosslinking and organization were investigated in human lung control, fibrotic and chronic obstructive pulmonary disease (COPD) tissue sections. Ultra-performance liquid chromatography and second harmonic generation microscopy measured pyridinoline crosslinks and the distribution of mature and immature collagens within the decellularized scaffolds, respectively. Fibrotic scaffolds had higher total collagen but less crosslinking per mole of collagen compared with COPD donors. Image analysis by second harmonic generation microscopy showed mature collagens populated airway or blood vessel walls in all three groups and in the parenchyma of fibrotic scaffolds. Immature collagens, on the other hand, were mainly localized to parenchymal regions in control and COPD scaffolds, with fewer immature collagens in fibrotic parenchyma. Additionally, quantification of the mature to immature collagen ratio in defined regions of control and diseased scaffolds showed increased organized collagen in fibrotic tissue. Our study shows that collagen crosslinking and organization are disrupted in fibrotic and COPD lungs and these changes may be compartment specific and can contribute to aberrant mechanical properties of diseased lungs. Our findings highlight that along with total collagen content, collagen crosslinking and organization are equally important while investigating collagen-mediated pathological changes in lung tissue. These changes may have implications for developing ECM-based therapeutics for patients with lung diseases.

molecular biology↗

bioRxiv2026

Collagen crosslinking and organizational patterns reflect common disease processes in idiopathic pulmonary fibrosis and non-resolving acute respiratory distress syndrome

RationaleFibrotic lung diseases, such as idiopathic pulmonary fibrosis (IPF) and fibroproliferative remodeling in acute respiratory distress syndrome (ARDS), are characterized by increased extracellular matrix (ECM) deposition. However, measuring collagen accumulation alone does not capture differences in ECM organization or biochemical maturation that may distinguish persistent fibrosis from potentially reversible remodeling. ObjectivesTo examine collagen organization characteristics and mature (pyridinoline) collagen crosslinking amount in established end stage fibrotic lung disease (IPF) and fibroproliferation following an acutely damaged lung (non-resolving (NR) ARDS) and to investigate any relationships in these parameters and temporal tissue remodeling. MethodsHuman lung tissue samples from control subjects, patients with IPF, and NR-ARDS were analyzed. Collagen amount and fiber organization were digitally quantified using picrosirius red staining. Mature collagen crosslinking was assessed by quantification of pyridinoline crosslinks. Measurements and Main ResultsLung tissue from both IPF and NR-ARDS lungs had higher collagen content compared with controls. Collagen fiber organization differed between groups. IPF lungs exhibited collagen architectures consistent with established fibrosis, whereas NR-ARDS lungs showed altered but less stabilized collagen organization despite similarly elevated collagen levels. Mature collagen crosslinks were significantly higher in IPF lungs but not in NR-ARDS lungs compared to controls. Integrated analyses identified distinct disease-associated ECM phenotypes, indicating that higher collagen abundance in NR-ARDS, unlike IPF, is not accompanied by more mature and persistent collagen crosslinking. ConclusionsDespite shared increases in collagen content, IPF and NR-ARDS lungs differ fundamentally in collagen organization and crosslinking maturity, suggesting differences in the reversibility of these conditions.

pathology↗

bioRxiv2026

Hydrogel-Embedded Precision-Cut Lung Slices Recapitulate Fibrotic Gene Expression and Enable Therapeutic Response Evaluation

Precision-cut lung slices (PCLS) retain the native cells and extracellular matrix that contribute to the structural and functional integrity of lung tissue. This technique enables the study of cell-matrix interactions and is particularly useful for pre-clinical pharmacological studies. More specifically, PCLS are widely used to model the complex pathophysiology of pulmonary fibrosis, an uncurable and progressive interstitial lung disease. Current ex vivo pulmonary fibrosis models expose PCLS to pro-fibrotic biochemical cues over a short timeframe (hours to days) and quickly collect samples for analysis due to viability concerns. This condensed timeline is a limitation to understanding chronic disease mechanisms. To extend the utility of ex vivo pulmonary fibrosis models, PCLS were embedded in engineered hydrogels and exposed to pro-fibrotic biochemical and biophysical cues. Hydrogel-embedded PCLS maintained greater than 80% total cell viability over 3 weeks in culture. Gene expression patterns in samples exposed to pro-fibrotic cues matched trends measured in human fibrotic lung tissue. Finally, treatment with Nintedanib, a Food and Drug Administration approved pulmonary fibrosis drug, moderately reduced fibroblast activation and influenced epithelial cell differentiation. Collectively, these results show that hydrogel-embedded PCLS models of pulmonary fibrosis extend our ability to study fibrotic processes ex vivo and, when applied to human tissues, present a new approach methodology for studying lung disease and treatment.

bioengineering↗

bioRxiv2026

Type VI collagen is proportionally lower around airways and blood vessels in idiopathic pulmonary fibrosis

Type VI collagen (COL6) is a key extracellular matrix protein that supports matrix organization and cell-matrix interactions, yet its regulation in idiopathic pulmonary fibrosis (IPF) remains poorly understood. Here, we characterize COL6 gene expression, spatial localization, remodeling, and functional effects of COL6-derived fragments. Analysis of publicly available single-cell RNA sequencing data from 30 controls and 32 pulmonary fibrosis patients revealed higher expression of COL6A1-A6 in fibrotic lungs, predominantly in mesenchymal cells (A1: p=0.0002, A2: p=0.0005, A3: p=2.5x10-5, A5: p=0.016, A6: p=0.007). Immunohistochemical analysis of lung tissue from never-smoker (n=9), ex-smoker (n=9) controls, and IPF patients (n=12) showed extensive COL6 localization across parenchyma, airways, and vessels. The proportion of COL61 and COL62 was lower around IPF vessels (1: p<0.001, 2: p=0.012), and COL62 was lower around IPF airways (p=0.033) compared with never-smokers. Quantification of COL6 remodeling fragments in lung tissue from never-smoker (n=3), ex-smoker (n=5) controls, and IPF patients (n=10) revealed that COL6 production (PRO-C6) localized around airways and vessels but was proportionally lower in IPF airways (never-smokers: p=0.0075). In contrast, COL6 degradation (C6M) was widely distributed throughout the tissue, with lower levels in IPF (never-smokers: p=0.0008). Functionally, COL6 and PRO-C6 increased fibroblast viability (COL6: p=0.002, PRO-C6: p=0.0021), while apoptosis was unaffected. Similar trends were observed in epithelial and endothelial cells. In summary, despite increased COL6 gene expression, IPF lungs exhibited lower proportions of COL6 protein and synthesis around airways and vessels, suggesting disrupted matrix organization, altered remodeling, and pro-survival effects that may contribute to fibroblast persistence and fibrosis progression. New & NoteworthyIn this study, we revealed that IPF lungs are characterized by increased type VI collagen (COL6) gene expression but lower COL6 protein and turnover proportions around airways and blood vessels compared with controls. COL6 and a fragment associated with its production (PRO-C6) increased lung fibroblast viability. These findings highlight that pulmonary fibrotic tissue is characterized by disrupted extracellular matrix and altered tissue remodeling and suggest that COL6 may contribute to fibroblast persistence and fibrosis progression.

molecular biology↗

bioRxiv2025

Fibroblast alignment is governed by stiffness interfaces in hydrogels.

Transitions in mechanical properties between different tissue scaffolds, such as extracellular matrices (ECMs), are common in the human body and influence cellular orientation. For example, in teeth, the abrupt transition between soft ([~]5 kPa) dental pulp and stiff (>100 kPa) dentin directs the alignment of odontoblasts. In this study, hydrogels, with defined mechanical transitions were used to evaluate the phenotypic response of fibroblasts to either a soft/soft (3 kPa/3 kPa) or soft/stiff (3 kPa/200 kPa) interface. Near the soft/soft interface fibroblasts aligned in a more parallel fashion to the interface (11{degrees} angle to the interface), compared to the more perpendicular fashion (69{degrees} angle to the interface) observed at the soft-stiff interface. Notably, regions of alignment also showed an increased proportion of alpha smooth muscle actin (SMA)-positive cells, indicating myofibroblast differentiation in response to the mechanical transition. These findings demonstrate that modifying a biomaterial by introducing an interface alters the bioactivity of responding cells solely through mechanical mechanisms, without any change to the cells biochemical environment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=147 HEIGHT=200 SRC="FIGDIR/small/695439v1_ufig1.gif" ALT="Figure 1000"> View larger version (42K): org.highwire.dtl.DTLVardef@d0ca04org.highwire.dtl.DTLVardef@17ee49forg.highwire.dtl.DTLVardef@1d389a5org.highwire.dtl.DTLVardef@f1b2a0_HPS_FORMAT_FIGEXP M_FIG C_FIG Schematic summary showing interface-induced fibroblast orientation and variety in phenotypic expression. On the bottom left the perpendicular orientation of fibroblast (skin tone) and myofibroblast (pink) on a soft/soft (3kPa/3kPa) GelMA hydrogel interface and on the right side the parallel orientation near a soft/stiff (3kPa/200kPa) GelMA hydrogel interface with greater collagen deposition, depicted by purple halos.

bioengineering↗

bioRxiv2025

A novel molecular interaction in bronchiolitis obliterans syndrome in lung transplantation patients: the role of SERPINA3 and osteoprotegerin

Background and objectiveChronic lung allograft dysfunction, significantly limits survival after lung transplantation. The obstructive phenotype bronchiolitis obliterans syndrome (BOS) is characterized by the abnormal activation of epithelium in airways accompanied by fibrotic changes with excessive deposition of extracellular matrix, resulting in narrowing and ultimately obliteration of airways. Mast cells, characterized by mediators such as tryptase and chymase, play a role in lung fibrosis. The proteins, osteoprotegerin (OPG) and SERPIN family member A 3 (SERPINA3) have previously been associated with progression of lung fibrosis. Tryptase-mast cells can produce OPG, while chymase released from mast cells interacts with SERPINA3. This study aimed to investigate if and how SERPINA3, OPG and tryptase/chymase-positive mast cells are related to fibrotic airway obliteration, and potentially show an association with BOS severity. MethodsSERPINA3 levels in serum from patients with or without BOS were examined using ELISA. In lung tissue from patients with BOS, we identified non-cartilaginous airways and classified them into normal, partially and completely obstructed airways. Immunohistochemistry was used for detection of SERPINA3, OPG, chymase and tryptase. Colocalization of, and interactions between, SERPINA3, OPG and tryptase were assessed by immunofluorescence, proximity ligation assay, and AlphaFold modeling. ResultsSERPINA3 levels in serum from BOS patients were higher compared to non-BOS patients. A low percentage of SERPINA3 and OPG was detected in partially and completely obstructed airways. Cells positive for OPG and SERPINA3 colocalized with tryptase-mast cells in airways from BOS lung tissue. OPG colocalized with SERPINA3 and their staining positively correlated in partially obstructed airways. In completely obstructed airways, OPG, SERPINA3 and tryptase staining areas all positively correlated with each other. ConclusionSERPINA3 and OPG are expressed by mast cells and these proteins may form a complex in lung tissue with potential for contributing to airway remodeling in BOS.

pathology↗

bioRxiv2025

Myeloid cell differentiation within extracorporeal membrane oxygenators in patients with ARDS

Extracorporeal membrane oxygenation is a last-resort rescue therapy for patients with acute respiratory distress syndrome (ARDS). The membrane oxygenator (MO) is prone to coagulation and dysfunction. Studies have shown that circulating cells can be retained within the MO, however, it is unclear what their cellular identity is. Here, we used single cell-RNA sequencing to characterize MO-resident and incoming venous PBMCs from ARDS patients. We find that MO contain both undifferentiated monocytes and differentiated macrophages, characterized by increased SPP1 expression. These results indicate that myeloid retention and differentiation occurs within MO, which might contribute to MO dysfunction.

cell biology↗

bioRxiv2025

Receptor agonist of NFκB signaling ligand directs lung epithelial cell expansion through RANK signaling

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death globally, with progressive emphysema driven by repeated epithelial damage and impaired repair. Recently, we found that secretion of the osteokine "receptor agonist of nuclear factor {kappa}B signaling ligand" (RANKL) is higher in lung fibroblasts from patients with COPD compared to control and that RANKL represses lung epithelial cell death. However, the underlying mechanism, its cross-species conservation and the involved epithelial cell types remain unclear. To investigate how RANKL affects lung epithelial cells, we used primary lung organoids from human and mouse epithelial cells and showed that RANKL supplementation increased alveolar organoid forming capacity in these cultures compared to vehicle-treated controls. In elastase-treated mice, RANKL was able to rescue the elastase-induced loss of epithelial cells compared to vehicle-treated controls and it augmented the proportion of epithelial cells in transitional states expressing Krt8 and MHCII. Using A549 epithelial cells to investigate whether RANK or the alternative receptor for RANKL, "leucine-rich repeat-containing G-protein coupled receptor 4" (LGR4) were responding to RANKL treatment, we found that RANKL most likely acts through RANK These results suggest that RANKL may enhance stem cell survival of primarily alveolar epithelial cells in both mice and humans. We therefore conclude that RANKL is another osteokine, in addition to periostin, osteopontin, osteoglycin, and osteoprotegerin, that has a role in lung tissue repair and that its signaling pathway could be explored for therapeutic applications. New & NoteworthyRANKL enhances human and murine alveolar epithelial cell expansion. Using organoids and an elastase injury model, we show RANKL promotes alveolar epithelial type II cell expansion and rescues transitional cell type loss. RANKL/RANK signaling therefore emerges as a conserved lung regenerative pathway and may be a potential therapeutic target for diseases like COPD with impaired epithelial repair.

cell biology↗

bioRxiv2025

Contrasting responses of control and fibrotic lung fibroblasts to fibrotic stimuli: the role of osteoprotegerin in extracellular matrix remodeling

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease characterized by dysregulated wound healing, leading to excessive production of extracellular matrix (ECM) proteins, particularly collagen, by activated fibroblasts. Osteoprotegerin (OPG), a soluble protein associated with ECM remodeling in bone, has been found in higher levels in serum and lung tissue of IPF patients compared to controls. However, whether OPG is associated with ECM remodeling by fibroblasts in lung fibrosis remains poorly understood. In this study we assessed differences in OPG levels in ECM-derived hydrogels from non-disease controls and patients with IPF encapsulated with primary human lung fibroblasts from control and patients with IPF (7 days). OPG levels were assessed in a collected culture medium and stained lung tissue sections, and related to biomechanical properties. Fibrotic human lung fibroblasts secreted and deposited more OPG compared to controls, which was observed in both non-diseased and IPF ECM hydrogels. OPG levels correlated significantly with matrix stiffness and collagen fiber structural properties, but only in IPF hydrogels, independent of fibroblast source. Strikingly, we also observed opposite correlations for control and fibrotic fibroblasts in fibrotic hydrogels. Control fibroblasts within a fibrotic microenvironment, secreted less OPG when hydrogel stiffness increased and deposited more OPG when collagen fibers were more aligned. Interestingly, fibrotic fibroblasts secreted more OPG when collagen fiber length increased and when collagen fiber curvature increased. Overall, our findings suggest that control and fibrotic lung fibroblasts exhibited opposite behavior with respect to OPG and ECM remodeling under fibrotic conditions and this may have consequences for matrix stiffness

cell biology↗

bioRxiv2025

It takes two: Aberrant repair and low-grade inflammation characterizes bronchiolitis obliterans syndrome after lung transplantation in serum proteomic analysis

AimThe obstructive phenotype of chronic lung allograft dysfunction, bronchiolitis obliterans syndrome (BOS), is diagnosed after lung transplantation (LTx) when irreversible airway obstruction is already present. This study aimed to investigate the fibrotic response and inflammation signals in serum of BOS patients. MethodsLTx patients transplanted at the University Medical Center Groningen between 2004 and 2017 were screened. Nineteen patients with BOS were selected and matched to 19 non-BOS patients. Only patients for whom lung function and longitudinal serum samples post-LTx were available were included. Enzyme-linked immunosorbent assays were performed for neoepitopes of collagen types I, III, and VI and osteoprotegerin (OPG) in serum. Additionally, serum samples were analyzed by label free liquid chromatography with tandem mass spectrometry proteomics analysis. ResultsCollagen neoepitopes did not differ significantly between BOS and non-BOS patients at any timepoint. OPG was significantly higher in non-BOS compared to BOS six months before BOS onset (p<0.04). In proteomics analysis, proteins indicating cell repair and proliferation, namely human type II keratin-6 and centromere protein F (both FDR<0.1), were significantly lower three months before BOS onset in BOS compared to non-BOS patients. C-reactive protein (FDR<0.05) and SERPINA3 (FDR<0.05) amongst others, were higher in end-stage BOS compared to non-BOS patients. ConclusionDifferences in expression of proteins that reflect the complex interplay between fibrosis and inflammation in BOS were identified. These proteins should be investigated and validated in larger cohorts and may aid in expanding knowledge about the development of BOS.

bioinformatics↗

bioRxiv2024

Interaction of osteoprotegerin with fibulin-1 is essential for extracellular matrix deposition in fibrotic lung tissue

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease with an unclear cause and no cure. Osteoprotegerin (OPG), a well-known regulator of bone extracellular matrix (ECM), is increased in pulmonary fibrosis and this is associated with lower lung function and IPF progression. Fibulin-1, a key ECM protein, is increased in lung fibroblasts and lung tissues from patients with IPF and high levels are predictive of a poor prognosis for these patients. We found a positive correlation between levels of OPG and fibulin-1 in serum from patients with IPF, but it is unknown if these proteins interact. This study aimed at investigating interactions between OPG and fibulin-1 in lung fibrosis, hypothesizing that OPG may form a complex with fibulin-1 thereby possibly influencing lung fibrosis. We investigated intracellular interactions between OPG and fibulin-1 in human lung fibroblasts, showing neither OPG nor fibulin-1 expression were dependent on each other. However, OPG protein deposition was significantly decreased in lung tissues of fibulin-1 knockout mice (fibulin-1-/-)compared to controls suggesting extracellular interactions. Subsequently, we detected colocalization of both proteins in both IPF and control lung tissues using immunofluorescence, with both of them also colocalizing with latent TGF{beta} binding protein 1 (LTBP1). Proximity ligation analyses confirmed close proximity of OPG to fibulin-1 and fibulin-1 to LTBP1, particularly in the interstitial regions of both control and IPF lung tissue, but not OPG and LTBP1. In conclusion, we found that OPG, fibulin-1 and LTBP1 seem to form a complex, with fibulin-1 playing a bridging role between OPG and LTBP1, in the extracellular environment. This complex may play a regulatory role in deposition of extracellular matrix in lung tissue.

pathology↗

bioRxiv2024

Compositional changes of the lung extracellular matrix in acute respiratory distress syndrome

BackgroundAcute respiratory distress syndrome (ARDS) is pathologically characterized by diffuse alveolar damage (DAD) and is associated with high morbidity and mortality rates. Remodeling of the extracellular matrix (ECM), which is pivotal for both tissue repair and organ recovery, may play a large role in persistent ARDS. This study investigated the compositional changes in the ECM in different DAD stages in ARDS. MethodsParaffin-embedded lung sections collected during autopsy or from post-transplant lungs were obtained from patients with ARDS (n=28) admitted to the University Medical Center Groningen between 2010-2020. Sections were stained histochemically, and immunohistochemically for collagen III 1 chain (Col IIIa1), IV 3 chain (Col IVa3), VI 1 chain (Col VIa1), periostin (PSTN), lumican (LUM), and fibronectin (FN). The sections were divided into 118 regions based on DAD stages (54 early vs 64 advanced). The differences in the expression of selected proteins were compared between DAD stages or across ARDS duration (<7days, 7-14days, >14days). The fiber pattern of Col VIa1 was analyzed using CellProfiler. ResultsHigher tissue density, lower proportional areas of Col IIIa1, Col IVa3, and LUM, and more concentrated Col VIa1 fibers were observed in the advanced DAD stage than in the early DAD stage. Areas with higher proportions of total collagen and FN, and lower proportional areas of Col IIIa1, Col IVa3, and LUM were detected in lung regions from patients with ARDS >14days duration. ConclusionsThese findings revealed proportional changes in ECM components, strongly suggesting that dynamic changes in ECM proteins play a role in pathophysiology in ARDS during progression.

molecular biology↗

bioRxiv2023

The lung extracellular matrix protein landscape in severe early-onset and moderate chronic obstructive pulmonary disease.

Extracellular matrix (ECM) remodeling has been implicated in the irreversible obstruction of airways and destruction of alveolar tissue in chronic obstructive pulmonary disease (COPD). Studies investigating differences in the lung ECM in COPD have mainly focused on some collagens and elastin, leaving an array of ECM components unexplored. We investigated the differences in the ECM landscape comparing severe-early onset (SEO-) COPD and moderate COPD to control lung tissue for collagen type I chain 1 (COL1A1), COL6A1, COL6A2, COL14A1, fibulin 2 and 5 (FBLN2, FBLN5), latent transforming growth factor-beta binding protein 4 (LTBP4), lumican (LUM), versican (VCAN), decorin (DCN), and elastin (ELN) using image analysis and statistical modelling. Percentage area and/or mean intensity of expression of LUM in the parenchyma, and COL1A1, FBLN2, LTBP4, DCN, and VCAN in the airway walls, was proportionally lower in COPD compared to controls. Lowered levels of most ECM proteins were associated with decreasing FEV1 measurements, indicating a relationship with disease severity. Furthermore, we identified six unique ECM signatures where LUM and COL6A1 in parenchyma and COL1A1, FBLN5, DCN, and VCAN in airway walls appear essential in reflecting the presence and severity of COPD. These signatures emphasize the need to examine groups of proteins to represent an overall difference in the ECM landscape in COPD, that are more likely to be related to functional effects, than individual proteins. Our study revealed differences in the lung ECM landscape between control and COPD and between SEO and moderate COPD signifying distinct pathological processes in the different subgroups. NEW & NOTEWORTHYOur study identified COPD-associated differences in the lung 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.

molecular biology↗

bioRxiv2023

Three dimensional fibrotic extracellular matrix directs microenvironment fiber remodeling by fibroblasts

Idiopathic pulmonary fibrosis (IPF), for which effective treatments are limited, results in excessive and disorganized deposition of an aberrant extracellular matrix (ECM). An altered ECM microenvironment is postulated to contribute to disease perpetuation in a feed-forward manner through inducing profibrotic behavior by lung fibroblasts, the main producers and regulators of ECM. Here, we examined this hypothesis in a 3D in vitro model system by growing primary human lung fibroblasts in ECM-derived hydrogels from non-fibrotic (control) or IPF lung tissue. Culture of fibroblasts in fibrotic hydrogels did not trigger a change in the overall amount of collagen or glycosaminoglycans but did cause a drastic change in fiber organization compared to culture in control hydrogels. Mechanical properties of fibrotic hydrogels were modified by fibroblasts while control hydrogels were not. These results illustrate how the 3D microenvironment plays a crucial role in directing cells to exhibit pro-fibrotic responses by providing biochemical and/or biomechanical cues.

pathology↗

bioRxiv2022

IL-11 disrupts alveolar epithelial progenitor function

IL-11 is linked to the pathogenesis of idiopathic pulmonary fibrosis (IPF), since IL-11 induces myofibroblast differentiation and stimulates their excessive collagen deposition in the lung. The alveolar architecture is disrupted in IPF, yet the effect of IL-11 on dysregulated alveolar repair associated with IPF remains to be elucidated. We hypothesized that epithelial-fibroblast communication associated with lung repair is disrupted by IL-11. Thus, we studied whether IL-11 affects the repair responses of alveolar lung epithelium using mouse lung organoids and precision cut lung slices (PCLS). Additionally, we assessed the anatomical distribution of IL-11 and IL-11 receptor in human control and IPF lungs using immunohistochemistry. IL-11 protein was observed in human control lungs in airway epithelium, macrophages and in IPF lungs, in areas of AT2 cell hyperplasia. IL-11R staining was predominantly present in smooth muscle and macrophages. In mouse organoid co-cultures of epithelial cells with lung fibroblasts, IL-11 decreased organoid number and reduced the fraction of pro-SPC expressing organoids, indicating dysfunctional regeneration initiated by epithelial progenitors. In mouse PCLS alveolar marker gene expression declined, whereas airway markers were increased. The response of primary human fibroblasts to IL-11 on gene expression level was minimal, though bulk RNA-sequencing revealed IL-11 modulated a number of processes which may play a role in IPF, including unfolded protein response, glycolysis and Notch signaling. In conclusion, IL-11 disrupts alveolar epithelial regeneration by inhibiting progenitor activation and suppressing the formation of mature alveolar epithelial cells. The contribution of dysregulated fibroblast - epithelial communication to this process appears to be limited.

cell biology↗

bioRxiv2022

Substrate stiffness engineered to replicate disease conditions influence senescence and fibrotic responses in primary lung fibroblasts

In idiopathic pulmonary fibrosis (IPF) there is excessive ECM deposition, increased stiffness and ultimately destruction of lung parenchyma. IPF presents mainly in the elderly, implying that senescence, a hallmark of ageing, contributes to disease progression. Several studies have reported that IPF is characterised by increased senescence and accumulating evidence suggests that structural changes, such as increased stiffness may contribute to senescence. This study therefore investigated if increased tissue stiffness could modulate markers of senescence and/or fibrosis in primary lung fibroblasts. Using hydrogels representing healthy and fibrotic stiffnesses, we cultured primary fibroblasts from non-diseased lung tissue on top of these hydrogels for up to seven days before assessing senescence and fibrosis markers. Fibroblasts cultured on stiff ({+/-}15kPa) hydrogels showed higher Yes-associated protein-1 (YAP) nuclear translocation compared to soft hydrogels. When looking at senescence-associated proteins we also found higher secretion of receptor activator of nuclear factor kappa-B ligand (RANKL) but no change in transforming growth factor-{beta}1 (TGF-{beta}1) or connective tissue growth factor (CTGF) expression and higher decorin protein deposition on stiff matrices. With respect to genes associated with fibrosis, fibroblasts on stiff hydrogels compared to soft had higher expression of smooth muscle alpha ()-2 actin (ACTA2), collagen (COL) 1A1 and fibulin-1 (Fbln1) and higher Fbln1 protein deposition after seven days. Our results show that exposure of lung fibroblasts to fibrotic stiffness activates genes and secreted factors that are part of fibrotic responses and part of the senescence-associated secretory profile (SASP). This overlap may contribute to the creation of a feedback loop whereby fibroblasts create a perpetuating cycle reinforcing disease progression in IPF.

cell biology↗