Changes In Extracellular Matrix Research Articles

Novel cardiac extracellular matrix biomarkers in STEMI: Associations with ischemic injury and long-term mortality.

We aimed to determine whether serum levels of proteins related to changes in cardiac extracellular matrix (ECM) were associated with ischemic injury assessed by cardiac magnetic resonance (CMR) and mortality in patients with ST-elevation myocardial infarction (STEMI). The concentrations of six ECM-related proteins (periostin, osteopontin, syndecan-1, syndecan-4, bone morphogenetic protein 7, and growth differentiation factor (GDF)-15) were measured in serum samples from patients on Day 1 and Month 4 after STEMI (n = 239). Ischemic injury was assessed by myocardial salvage index, microvascular obstruction, infarct size, and left ventricular function measured by CMR conducted during the initial admission (median 2 days after admission) and after 4 months. All-cause mortality was recorded after a median follow-up time of 70 months. Levels of periostin increased from Day 1 to Month 4 after hospitalization, while the levels of GDF-15, osteopontin, syndecan-1, and syndecan-4 declined. At both time points, high levels of syndecan-1 were associated with microvascular obstruction, large infarct size, and reduced left ventricular ejection fraction, whereas high levels of syndecan-4 at Month 4 were associated with a higher myocardial salvage index and less dilatation of the left ventricle. Higher mortality rates were associated with periostin levels at both time points, low syndecan-4 levels at Month 4, or high GDF-15 levels at Month 4. In patients with STEMI, we found an association between serum levels of ECM biomarkers and ischemic injury and mortality. The results provide new insight into the role ECM components play in ischemic injury following STEMI and suggests a potential for these biomarkers in prognostication after STEMI.

Maximizing the Therapeutic Effect of Endothelin Receptor Antagonists in Pulmonary Fibrosis: A Paradigm for Treating the Disease.

Using a lipopolysaccharide model of acute lung injury, we previously showed that endothelin-1 (ET-1), a potent mediator of vasoconstriction, may act as a "gatekeeper" for the influx of inflammatory cells into the lung. These studies provided a rationale for testing the effect of HJP272, an endothelin receptor antagonist (ERA), in hamster models of pulmonary fibrosis induced by intratracheal instillation of either bleomycin (BLM) or amiodarone (AM). To determine the temporal effects of blocking ET-1 activity, animals were given HJP272 either 1 h before initiation of lung injury or 24 h afterward. The results indicated that pretreatment with this agent caused significant reductions in various inflammatory parameters, whereas post-treatment was ineffective. This finding suggests that ERAs are only effective at a very early stage of pulmonary fibrosis and explains their lack of success in clinical trials involving patients with this disease. Nevertheless, ERAs could serve as prophylactic agents when combined with drugs that may induce pulmonary fibrosis. Furthermore, developing a biomarker for the initial changes in the lung extracellular matrix could increase the efficacy of ERAs and other therapeutic agents in preventing the progression of the disease. While no such biomarker currently exists, we propose the ratio of free to peptide-bound desmosine, a unique crosslink of elastin, as a potential candidate for detecting the earliest modifications in lung microarchitecture associated with pulmonary fibrosis.

TSG-6 mediated extracellular matrix modifications regulate hypoxic-ischemic brain injury.

Proteoglycans containing link-domains modify the extracellular matrix (ECM) to regulate cellular homeostasis and can also sensitize tissues/organs to injury and stress. Hypoxic-Ischemic (H-I) injury disrupts cellular homeostasis by activating inflammation and attenuating regeneration and repair pathways. In the brain, the main component of the ECM is the glycosaminoglycan (GAG), Hyaluronic Acid (HA), but whether HA modifications of the ECM regulate cellular homeostasis and response to H-I injury is not known. In this report, employing both male and female mice, we demonstrate that link-domain containing proteoglycan, TNFα-stimulated gene-6 (TSG-6), is active in the brain from birth onwards and differentially modifies ECM HA during discrete neurodevelopmental windows. ECM HA modification by TSG-6 enables it to serve as a developmental switch to regulate activity of the Hippo pathway effector protein, Yes Associated Protein 1 (YAP1) in the maturing brain and in response to H-I injury. Mice that lack TSG-6 expression display dysregulated expression of YAP1 targets, excitatory amino acid transporter 1 (EAAT1; GLAST) and 2 (EAAT2; GLT-1). Dysregulation of YAP1 activation in TSG-6-/- mice coincides with age- and sex-dependent sensitization of the brain to H-I injury such that 1-week-old neonates display an anti-inflammatory response in contrast to an enhanced pro-inflammatory injury reaction in 3-month-old adult males but not females. Our findings thus support that a key regulator of age- and sex-dependent H-I injury response in the mouse brain is modulation of the Hippo-YAP1 pathway by TSG-6 dependent ECM modifications.Significance Statement Hypoxic-Ischemic (H-I) injury is a common cause of morbidity and mortality worldwide. Numerous genomic and proteomic screens have identified changes in extracellular matrix (ECM) as the most common finding, yet the downstream mechanistic insights remain obscure. We found that proteoglycan, TNF stimulated gene-6 (TSG-6) dependent ECM modifications regulate the activity of the Hippo pathway effector, the RNA transcription co-activator, Yes Associated Protein 1 (YAP1). Dysregulation of YAP1 activation in TSG-6-/- mice coincided with age- and sex-dependent sensitization of the brain to H-I injury such that neonates displayed an anti-inflammatory response in contrast to an enhanced pro-inflammatory injury reaction in adults. Thus, our findings establish TSG-6-dependent ECM modifications as a key regulator of age- and sex-dependent H-I injury responses.

Abstract 160: FGFR1+ cancer associated fibroblasts (CAFs) produce an extracellular matrix (ECM) that curbs infiltration of phagocytic tumor-associated macrophages (TAMs)

Abstract About 40% of diffuse large B-cell lymphoma (DLBCL) pts do not respond to immunochemotherapy. In human and murine models, we and others have shown that the lymphoma microenvironment (LME) changes with disease progression and treatment resistance. This lymphoma cell-LME co-evolutionary process results in expansion of treatment-resistant lymphoma cells as well as reduced infiltration of T cells and reprogramming of CAFs and TAMs into immune suppressive entities. Our analysis of relapse or refractory (RR)-DLBCLs showed not only an immune depleted LME but also an enrichment of CAFs harboring activation of fibroblast growth factor receptor (FGFR1+). Since FGFR1 inhibitors (FGFR1i) are clinically available, we sought to determine its anti-neoplastic effect on DLBCL. We first confirmed that lymphoma cells, including murine and human, and primary and RR-DLBCLs, did not express FGFR1. Accordingly, no anti-tumoral effect was detected when the selective FGFR1i SSR128129E was administered in vitro to a lymphoma cell panel. However, oral administration of FGFR1i to pre-clinical lymphoma models including two RR-DLBCL patient-derived xenografts (PDX) and four syngeneic murine models representing distinct DLBCL genetic subtypes produced a significant anti-lymphoma effect in all cases. In addition to decreased lymphoma cells, we observed increase in the ECM and TAM infiltration, even in the murine models, suggesting that FGFR1i reprogrammed the CAFs. We thus conducted matrisome analysis (i.e., ECM proteomics) in a murine model (p53 mutant) and found a significant up-regulation of proteoglycans and the immune active glycoproteins decorin, lumican and byglican (q-value <0.05 vs. vehicle). To determine whether these ECM changes affect lymphoma cells, we performed 3D co-cultures of lymphoma cells embedded into de-celularized ECM obtained from FGFR1i vs. vehicle mice. We found that FGFR1i-ECM (vs. vehicle-ECM) modifies the secretome of lymphoma cells by upregulating several cytokines including IL6, IL16 and TNF-alpha. To further characterize the functional state of CAFs and TAMs, we conducted single cell RNA-seq in the two RR-DLBCL PDXs treated as before. We found that FGFR1-CAFs in the LME of FGFR1i tumors (vs. vehicle) were reprogrammed into inflammatory-like CAFs characterized by the expression of several monocyte/macrophage chemotactic factors including CCL2, CCL7, CXCL3, and CXCL12. Consequent with these findings we not only observed an increase infiltration of TAMs in the LME of FGFR1i tumors but also that they were reprogrammed in phagocytic phenotypes. In sum, our results suggest that CAF-FGFR1+ produce an immune “silent” ECM that characterizes RR-DLBCL while FGFR1i reverses this ECM phenotype ultimately resulting in the infiltration of antitumoral TAMs, delineating a novel ECM-directed therapeutic approach for this disease. Citation Format: Nicolás Di Siervi, Maria Victoria Revuelta, Nahuel Zamponi, Giorgio Inghirami, Leandro Cerchietti. FGFR1+ cancer associated fibroblasts (CAFs) produce an extracellular matrix (ECM) that curbs infiltration of phagocytic tumor-associated macrophages (TAMs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 160.

Production of Cardiac Extracellular Matrix from Adult Human Fibroblasts for Culture Dish Coating.

The myocardium is composed of cardiomyocytes and an even greater number of fibroblasts, the latter being responsible for extracellular matrix production. From the early stages of heart development throughout the lifetime, in both normal and pathological conditions, the composition of the extracellular matrix changes and influences myocardium structure and function. The purpose of the method described here is to obtain the substrate for the culture of cardiac cells in vitro (termed cardiac ECM), mimicking the myocardial extracellular matrix in vivo. To this end, fibroblasts isolated from the adult human heart were cultured to confluence on gelatin-coated dishes to produce the myocardium-specific extracellular matrix. The subsequent removal of cardiac fibroblasts, while preserving the deposited cardiac ECM, produced the substrate for studying the influence of the myocardium-specific extracellular matrix on other cells. Importantly, the composition of the fibroblast-derived coating of the culture dish changes according to the in vivo activity of the fibroblasts isolated from the heart, allowing subsequent studies of cell-matrix interactions in different normal and pathological conditions.

Abstract 4280: Regulatory T cells contribute to tumor cell dissemination by extracellular matrix remodeling

Abstract Regulatory T (Treg) cells function to enforce peripheral tolerance and are potent suppressors of tumor immunity. In breast cancer, we have shown that Treg cells promote tumor growth by favoring alternative activation of macrophages via suppression of IFN-γ. The tumor-associated extracellular matrix (ECM) is a key regulator of metastatic dissemination and is emerging as a critical regulator of tumor immunity. However, the reciprocal effects of the immune system on the ECM remain elusive. Using murine in vivo, ex vivo and bioengineering models we describe Treg cell-dependent changes in the tumor ECM that facilitate tumor cell movement and metastatic dissemination. Further, Treg cell-dependent matrisome signatures correlate with survival in human breast cancer samples. This work underscores a previously unrecognized role of Treg cells on the ECM that facilitates metastasis and is consistent with tissue Treg cell emergent function as critical regulators of tissue repair and cancer. Citation Format: Ailen Garcia-Santillan, Jessanne Y. Lichtenberg, He Shen, Mikhail G. Dozmorov, Amy L. Olex, Priscilla Y. Hwang, Paula D. Bos. Regulatory T cells contribute to tumor cell dissemination by extracellular matrix remodeling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4280.

Remodeling of Murine Branch Pulmonary Arteries Under Chronic Hypoxia and Short-Term Normoxic Recovery.

Chronic hypoxia plays a central role in diverse pulmonary pathologies, but its effects on longitudinal changes in the biomechanical behavior of proximal pulmonary arteries remain poorly understood. Similarly, effects of normoxic recovery have not been well studied. Here, we report hypoxia-induced changes in composition, vasoactivity, and passive biaxial mechanics in the main branch pulmonary artery of male C57BL/6J mice exposed to 10% FiO2 for 1, 2, or 3 weeks. We observed significant changes in extracellular matrix, and consequently wall mechanics, as early as 1 week of hypoxia. While circumferential stress and stiffness returned toward normal values by 2-3 weeks of hypoxia, area fractions of cytoplasm and thin collagen fibers did not return toward normal until after 1 week of normoxic recovery. By contrast, elastic energy storage and overall distensibility remained reduced after 3 weeks of hypoxia as well as following 1 week of normoxic recovery. While smooth muscle and endothelial cell responses were attenuated under hypoxia, smooth muscle but not endothelial cell responses recovered following 1 week of subsequent normoxia. Collectively, these data suggest that homeostatic processes were unable to preserve or restore overall function, at least over a brief period of normoxic recovery. Longitudinal changes are critical in understanding large pulmonary artery remodeling under hypoxia, and its reversal, and will inform predictive models of vascular adaptation.

Mammary tissue-derived extracellular matrix hydrogels reveal the role of irradiation in driving a pro-tumor and immunosuppressive microenvironment

Radiation therapy (RT) is essential for triple negative breast cancer (TNBC) treatment. However, patients with TNBC continue to experience recurrence after RT. The role of the extracellular matrix (ECM) of irradiated breast tissue in tumor recurrence is still unknown. In this study, we evaluated the structure, molecular composition, and mechanical properties of irradiated murine mammary fat pads (MFPs) and developed ECM hydrogels from decellularized tissues (dECM) to assess the effects of RT-induced ECM changes on breast cancer cell behavior. Irradiated MFPs were characterized by increased ECM deposition and fiber density compared to unirradiated controls, which may provide a platform for cell invasion and proliferation. ECM component changes in collagens I, IV, and VI, and fibronectin were observed following irradiation in both MFPs and dECM hydrogels. Encapsulated TNBC cell proliferation and invasive capacity was enhanced in irradiated dECM hydrogels. In addition, TNBC cells co-cultured with macrophages in irradiated dECM hydrogels induced M2 macrophage polarization and exhibited further increases in proliferation. Our study establishes that the ECM in radiation-damaged sites promotes TNBC invasion and proliferation as well as an immunosuppressive microenvironment. This work represents an important step toward elucidating how changes in the ECM after RT contribute to breast cancer recurrence.

Abstract A003: Characterizing DNA methylation patterns driving chemotherapy resistance in ovarian high-grade serous carcinoma

Abstract To characterize the role of DNA methylation (DNAm) in chemotherapy response, we analyzed whole-genome DNAm data integrated with transcriptome from 67 samples of 17 patients with ovarian high grade serous carcinoma (HGSC) belonging to the prospective, longitudinal, multi-region DECIDER trial (NCT04846933). We used a novel decomposition method, which allows separating the effects of tumor microenvironment and treatment, tissue, and patient specific changes, facilitating the integration of the heterogeneous collection of samples. We firstly characterized DNAm alterations between tissue sites. Our results show that the cancer spread from tubo-ovarian sites to metastatic deposits is accompanied by moderate changes that employ cell junctions and focal adhesions. The most drastic change in the tissue intrinsic DNAm profiles implicated upregulation of members of the ATP-binding-cassette (ABC) family of transporters, including such multidrug resistance-associated genes as ABCC2, ABCC3, and ABCC4 in omentum. We then proceeded to characterize the DNAm changes during treatment. Our results reveal that DNAm plays a distinct role in emergence, driving, and regulation of both preexisting and acquired resistance to chemotherapy. We observed that patient-specific DNAm background shows enormous intra- and intertumor heterogeneity and sustains multiple driver mechanisms to resist chemotherapy-induced cell death already prior to treatment. We also observed that neoadjuvant chemotherapy (NACT) results in emergence of resistance via acquired, tissue specific DNAm alterations in DNA damage repair, apoptosis, cellular senescence, and drug efflux. Pathway analyses show that treatment-naïve tumors from patients with poor treatment outcome have DNAm-induced upregulation of key resistance promoting signaling pathways, such as PI3K/Akt, mTOR, and Rap1 cascades. Hypoxic transcriptional program activated via HIF-1 signaling was significantly altered in poorly responding patients, accompanied by changes in extracellular matrix instigated by integrins ITGB1 and ITGA5. Tumors of patients with refractory disease demonstrated DNAm changes in genes involved in tumor-promoting chronic inflammation driven by elevation of tumor necrosis factor. NACT treatment resulted in very few changes to these DNA aberrations and no acquired mechanisms, suggesting that intrinsic DNAm patient profiles accommodate multiple drivers for tumor progression and chemoresistance. In conclusion, using a large whole-sequencing DNAm dataset we elucidated the major underlying mechanisms of acquired platinum resistance, which provide possible targets for improving platinum sensitivity. Validation of these results and the intrinsic ability of HGSC to resist platinum-based treatment is currently on-going in our recently sequenced DNAm batch consisting of 400 samples of 135 HGSC patients. Citation Format: Alexandra Lahtinen, Giovanni Marchi, Kari Lavikka, Giulia Micoli, Susanna Holmström, Elsi Pöllänen, Ilari Maarala, Daria Afenteva, Yilin Li, Taru A. Muranen, Jaana Oikkonen, Kaisa Huhtinen, Anni Virtanen, Johanna Hynninen, Antti Häkkinen, Sampsa Hautaniemi. Characterizing DNA methylation patterns driving chemotherapy resistance in ovarian high-grade serous carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A003.

Dynamic relationship among extracellular matrix and body wall cells in Hirudo verbana morphogenesis

A great bulk of recent experimental evidence suggests the key role of the complex crosstalk between the extracellular matrix (ECM) and the cellular component of tissues during morphogenesis and embryogenesis. In particular, remodeling of the ECM and of its physical interactions pattern with surrounding cells represent two crucial processes that might be involved in muscle development. However, little information is available on this topic, especially on invertebrate species. To obtain new insights on how tuning the ECM microenvironment might drive cellular fate during embryonic development, we used the invertebrate medicinal leech Hirudo verbana as a valuable experimental model, due to its simple anatomy and the recapitulation of many aspects of the basic biological processes of vertebrates. Our previous studies on leech post-embryonic development have already shown the pivotal role of ECM changes during the growth of the body wall and the role of Yes-associated protein 1 (YAP1) in mechanotransduction. Here, we suggest that the interactions between stromal cell telocytes and ECM might be crucial in driving the organization of muscle layers during embryogenesis. Furthermore, we propose a possible role of the pleiotropic enzyme HvRNASET2 as a possible modulator of collagen deposition and ECM remodeling not only during regenerative processes (as previously demonstrated) but also in embryogenesis.

Neutrophil Activity and Extracellular Matrix Degradation: Drivers of Lung Tissue Destruction in Fatal COVID-19 Cases and Implications for Long COVID.

Pulmonary fibrosis, severe alveolitis, and the inability to restore alveolar epithelial architecture are primary causes of respiratory failure in fatal COVID-19 cases. However, the factors contributing to abnormal fibrosis in critically ill COVID-19 patients remain unclear. This study analyzed the histopathology of lung specimens from eight COVID-19 and six non-COVID-19 postmortems. We assessed the distribution and changes in extracellular matrix (ECM) proteins, including elastin and collagen, in lung alveoli through morphometric analyses. Our findings reveal the significant degradation of elastin fibers along the thin alveolar walls of the lung parenchyma, a process that precedes the onset of interstitial collagen deposition and widespread intra-alveolar fibrosis. Lungs with collapsed alveoli and organized fibrotic regions showed extensive fragmentation of elastin fibers, accompanied by alveolar epithelial cell death. Immunoblotting of lung autopsy tissue extracts confirmed elastin degradation. Importantly, we found that the loss of elastin was strongly correlated with the induction of neutrophil elastase (NE), a potent protease that degrades ECM. This study affirms the critical role of neutrophils and neutrophil enzymes in the pathogenesis of COVID-19. Consistently, we observed increased staining for peptidyl arginine deiminase, a marker for neutrophil extracellular trap release, and myeloperoxidase, an enzyme-generating reactive oxygen radical, indicating active neutrophil involvement in lung pathology. These findings place neutrophils and elastin degradation at the center of impaired alveolar function and argue that elastolysis and alveolitis trigger abnormal ECM repair and fibrosis in fatal COVID-19 cases. Importantly, this study has implications for severe COVID-19 complications, including long COVID and other chronic inflammatory and fibrotic disorders.

A150 DEVELOPMENT OF MIMETIC MATRICES AS INSTRUCTIVE ORGANOIDS MICROENVIRONMENT FOR THE STUDY OF COLONIC DISEASES

Abstract Background The functional complexity of the colonic epithelium is dependent on its interaction with the microenvironment involving gradients of soluble factors, extracellular matrix (ECM) proteins and stiffness. The influence of dynamic changes in the ECM has been observed in tumours, with variations in protein expression and rigidity. Their biomolecular impacts on epithelial cell behaviour are less studied due to the structural complexity of the matrix. Organoids offers a novel approach for the study of ECM biodynamics, as they require a matrix (Matrigel) to develop. Previous work showed that it is possible to grow organoids in hydrogels other than Matrigel. To evaluate the effect of matrix composition alteration on cancer initiation, we developed biofunctionalized composite hydrogels that mimic the ECM changes (chemical and physical) observed in the BmpR1a-deficient telocytes Foxl1 + (Bmpr1a△Foxl1+) mouse model of colorectal cancer (CRC) initiation. Aims The development of mimetic matrices, in association with organoids, would enable us to uncover the impact of matrix deregulation on colonic cells behaviour in pathogenesis process. Methods These hydrogels were made of alginate and 8-arm polyethylene glycol- vinyl sulfone (PEG) macromers bearing cysteine residues (CYS) and peptides. Four peptides derived from fibronectin, laminin 111, collagen I and collagen IV were used to mimic the ECM changes in the Bmpr1a△Foxl1+ colon. The grafting of CYS on alginate or peptides on PEG macromers was first characterized by thiol quantification assays. The non-grafted peptides were also analysed by uHPLC. Stiffness of the hydrogels was then determined by dynamic mechanical analysis. Finally, normal mouse organoids were seeded on hydrogels and evaluated for survival by live/dead labeling and proliferation by Alamar blue assays. Matrigel was used as a control. Results Chemical characterization revealed that CYS were grafted onto the alginate chain at around 190 μmol/g alginate. The PEG macromers were functionalized with four peptides at concentration varying from 0.25 to 1.5 mM. Rigidity of the hydrogels depends on the concentration of alginate used where lower concentration leads to soft matrix (0.5 kPa, homeostasis) and high concentration produced a stiff matrix (4 kPa, diseased). Organoids seeded in these mimetic composite hydrogels survived and proliferated in comparison to alginate alone. Conclusions Our results indicate that we can develop mimetic composite hydrogels where colon organoids can survive and thrive. This is a breakthrough model for defining the roles of ECM mechanical and biochemical stimuli in epithelial behaviour during the initiation and development of CRC. Funding Agencies CIHR

Possible involvement of HtrA1 serine protease in the onset of osteoporotic bone extracellular matrix changes

High-temperature requirement A1 (HtrA1), a multidomain serine protease acting on Extracellular matrix (ECM) rearrangement, is also secreted by osteoblasts and osteoclasts. Recent and conflicting literature highlights HtrA1's role as a controller of bone remodeling, proposing it as a possible target for pathologies with unbalanced bone resorption, like Osteoporosis (OP). To add knowledge on this molecule function in bone physiopathology, here we compared HtrA1 distribution in the ECM of healthy (H) and OP bone tissue, also examining its localization in the sites of new bone formation. HtrA1 was homogeneously expressed in the mature bone ECM of H tissue showing a 55.6 ± 16.4% of the stained area, with a significant (p=0.0001) decrease in OP percentage stained area (21.1 ± 13.1). Moreover, HtrA1 was present in the endosteum and cells involved in osteogenesis, mainly in those “entrapped” in woven bone, whereas osteocytes in mature lamellar bone were negative. Based on our previous observation in OP tissue of a significantly increased expression of Decorin and Osteocalcin, both involved in bone mineralization and remodeling and equally substrates for HtrA1, we speculate that HtrA1 by controlling the proper amount of Decorin and Osteocalcin favors normal bone maturation and mineralization. Besides, we suggest that late-osteoblasts and pre-osteocytes secrete HtrA1 in the adjacent matrix whilst proceeding with their maturation and that HtrA1 expression is further modified during the remodeling from woven to the lamellar bone. Overall, our data suggest HtrA1 as a positive regulator of bone matrix formation and maturation: its reduced expression in mature OP bone, affecting protein content and distribution, could hamper correct bone remodeling and mineralization.

Adipose Tissue Analysis Toolkit (ATAT) for automated analysis of adipocyte size and extracellular matrix in white adipose tissue.

The pathological expansion of white adipose tissue (WAT) in obesity involves adipocyte hypertrophy accompanied by expansion of the collagen-rich pericellular extracellular matrix (ECM) and development of crown-like structures (CLS). Traditionally, WAT morphology is assessed through immunohistochemical analysis of WAT sections. However, manual analysis of large histological sections is time-consuming, and the available digital tools for analyzing adipocyte size and pericellular ECM are limited. To address this gap, the authors developed the Adipose Tissue Analysis Toolkit (ATAT), an ImageJ plugin facilitating analysis of adipocyte size, WAT ECM, and CLS. ATAT utilizes local and image-level differentials in pixel intensity to independently threshold image background, distinguishing adipocyte-free tissue without user input. It accurately captures adipocytes in histological sections stained with common dyes and automates the analysis of adipocyte cross-sectional area, total-field, and localized region-of-interest ECM. ATAT allows fully automated batch analysis of histological images using default or user-defined adipocyte detection parameters. ATAT provides several advantages over existing WAT image analysis tools, enabling high-throughput analyses of adipocyte-specific parameters and facilitating the assessment of ECM changes associated with WAT remodeling due to weight changes and other pathophysiological alterations that affect WAT function.

Sox9 Accelerates Vascular Aging by Regulating Extracellular Matrix Composition and Stiffness.

Vascular calcification and increased extracellular matrix (ECM) stiffness are hallmarks of vascular aging. Sox9 (SRY-box transcription factor 9) has been implicated in vascular smooth muscle cell (VSMC) osteo/chondrogenic conversion; however, its relationship with aging and calcification has not been studied. Immunohistochemistry was performed on human aortic samples from young and aged patients. Young and senescent primary human VSMCs were induced to produce ECM, and Sox9 expression was manipulated using adenoviral overexpression and depletion. ECM properties were characterized using atomic force microscopy and proteomics, and VSMC phenotype on hydrogels and the ECM were examined using confocal microscopy. In vivo, Sox9 was not spatially associated with vascular calcification but correlated with the senescence marker p16 (cyclin-dependent kinase inhibitor 2A). In vitro Sox9 showed mechanosensitive responses with increased expression and nuclear translocation in senescent cells and on stiff matrices. Sox9 was found to regulate ECM stiffness and organization by orchestrating changes in collagen (Col) expression and reducing VSMC contractility, leading to the formation of an ECM that mirrored that of senescent cells. These ECM changes promoted phenotypic modulation of VSMCs, whereby senescent cells plated on ECM synthesized from cells depleted of Sox9 returned to a proliferative state, while proliferating cells on a matrix produced by Sox9 expressing cells showed reduced proliferation and increased DNA damage, reiterating features of senescent cells. LH3 (procollagen-lysine, 2-oxoglutarate 5-dioxygenase 3) was identified as an Sox9 target and key regulator of ECM stiffness. LH3 is packaged into extracellular vesicles and Sox9 promotes extracellular vesicle secretion, leading to increased LH3 deposition within the ECM. These findings highlight the crucial role of ECM structure and composition in regulating VSMC phenotype. We identify a positive feedback cycle, whereby cellular senescence and increased ECM stiffening promote Sox9 expression, which, in turn, drives further ECM modifications to further accelerate stiffening and senescence.

Matrix viscoelasticity promotes liver cancer progression in the pre-cirrhotic liver.

Type 2 diabetes mellitus is a major risk factor for hepatocellular carcinoma (HCC). Changes in extracellular matrix (ECM) mechanics contribute to cancer development1,2, and increased stiffness is known to promote HCC progression in cirrhotic conditions3,4. Type 2 diabetes mellitus is characterized by an accumulation of advanced glycation end-products (AGEs) in the ECM; however, how this affects HCC in non-cirrhotic conditions is unclear. Here we find that, in patients and animal models, AGEs promote changes in collagen architecture and enhance ECM viscoelasticity, with greater viscous dissipation and faster stress relaxation, but not changes in stiffness. High AGEs and viscoelasticity combined with oncogenic β-catenin signalling promote HCC induction, whereas inhibiting AGE production, reconstituting the AGE clearance receptor AGER1 or breaking AGE-mediated collagen cross-links reduces viscoelasticity and HCC growth. Matrix analysis and computational modelling demonstrate that lower interconnectivity of AGE-bundled collagen matrix, marked by shorter fibre length and greater heterogeneity, enhances viscoelasticity. Mechanistically, animal studies and 3D cell cultures show that enhanced viscoelasticity promotes HCC cell proliferation and invasion through an integrin-β1-tensin-1-YAP mechanotransductive pathway. These results reveal that AGE-mediated structural changes enhance ECM viscoelasticity, and that viscoelasticity can promote cancer progression in vivo, independent of stiffness.

The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis.

Studies on the changes of extracellular matrix (ECM) in pelvic organ prolapse (POP) are still controversial. To identify the changes in the ECM in POP patients. Comprehensive searching in Embase, PubMed, Web of Science and the Cochrane Library was carried out until 23 February 2023. Studies comparing the protein levels of ECM-related components between women with and without POP. Quality and risk of bias were assessed using the Agency for Healthcare Research and Quality assessment. Indicators were pooled with random or fixed effect meta-analysis based on heterogeneityand sub-grouped analysed by the biopsy site. Thirty cross-sectional studies were included, comprising 840 POP cases and 755 controls. Overall results showed that the expression of type III collagen (COLIII) and several matrix metalloproteinases (MMP-1, -2 and -9) were increased, whereas those of type I collagen (COLI), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were decreased in patients with POP. Subgroup analysis showed that the expression of COLIII in the anterior vaginal wall (AVW) and COLIII, MMP-2 and -9 in the uterosacral ligament (USL) were consistent with the overall results. However, the expression of COLI and MMP-1 in the AVW showed no difference and the expression of COLI and MMP-1 in the USL is still controversial based on current studies. Patients with POP have lower expression of COLI and TIMP-1 and higher expression of COLIII and MMPs compared with non-POP cases, but further studies are required to investigate in specified anatomical sites.

Uncovering Novel Extracellular Matrix Transcriptome Alterations in Lesions of Multiple Sclerosis.

The extracellular matrix (ECM) of the central nervous system (CNS) is an interconnected network of proteins and sugars with critical roles in both homeostasis and disease. In neurological diseases, excessive ECM deposition and remodeling impact both injury and repair. CNS lesions of multiple sclerosis (MS), a chronic inflammatory and degenerative disease, cause prominent alterations of the ECM. However, there are a lack of data investigating how the multitude of ECM members change in relation to each other and how this affects the MS disease course. Here, we evaluated ECM changes in MS lesions compared to a control brain using databases generated in-house through spatial mRNA-sequencing and through a public resource of single-nucleus RNA sequencing previously published by Absinta and colleagues. These results underline the importance of publicly available datasets to find new targets of interest, such as the ECM. Both spatial and public datasets demonstrated widespread changes in ECM molecules and their interacting proteins, including alterations to proteoglycans and glycoproteins within MS lesions. Some of the altered ECM members have been described in MS, but other highly upregulated members, including the SPARC family of proteins, have not previously been highlighted. SPARC family members are upregulated in other conditions by reactive astrocytes and may influence immune cell activation and MS disease course. The profound changes to the ECM in MS lesions deserve more scrutiny as they impact neuroinflammation, injury, and repair.

Dynamic changes in mitral valve extracellular matrix, tissue mechanics and function in a mouse model of Marfan syndrome

ObjectiveMouse models of Marfan syndrome (MFS) with Fibrillin 1 (Fbn1) variant C1041G exhibit cardiovascular abnormalities, including myxomatous valve disease (MVD) and aortic aneurism, with structural extracellular matrix (ECM) dysregulation. In this study, we examine the structure-function-mechanics relations of the mitral valve related to specific transitions in ECM composition and organization in progressive MVD in MFS mice from Postnatal day (P)7 to 1 year-of-age. Approach and resultsMechanistic links between mechanical forces and biological changes in MVD progression were examined in Fbn1C1041G/+ MFS mice. By echocardiography, mitral valve dysfunction is prevalent at 2 months with a decrease in cardiac function at 6 months, followed by a preserved cardiac function at 12 months. Mitral valve (MV) regurgitation occurs in a subset of mice at 2–6 months, while progressive dilatation of the aorta occurs from 2 to 12 months. Mitral valve tissue mechanical assessments using a uniaxial Permeabilizable Fiber System demonstrate decreased stiffness of MFS MVs at all stages. Histological and microscopic analysis of ECM content, structure, and fiber orientation demonstrate that alterations in ECM mechanics, composition, and organization precede functional abnormalities in Fbn1C1041G/+MFS MVs. At 2 months, ECM abnormalities are detected with an increase in proteoglycans and decreased stiffness of the mitral valve. By 6–12 months, collagen fiber remodeling is increased with abnormal fiber organization in MFS mitral valve leaflets. At the same time, matrifibrocyte gene expression characteristic of collagen-rich connective tissue is increased, as detected by RNA in situ hybridization and qPCR. Together, these studies demonstrate early prevalence of proteoglycans at 2 months followed by upregulation of collagen structure and organization with age in MVs of MFS mice. ConclusionsAltogether, our data indicate dynamic regulation of mitral valve structure, tissue mechanics, and function that reflect changes in ECM composition, organization, and gene expression in progressive MVD. Notably, increased collagen fiber organization and orientation, potentially dependent on increased matrifibrocyte cell activity, is apparent with altered mitral valve mechanics and function in aging MFS mice.

Renal denervation restores biomechanics of carotid arteries in a rat model of hypertension

The prevalence of hypertension increases with aging and is associated with increased arterial stiffness. Resistant hypertension is presented when drug treatments fail to regulate a sustained increased blood pressure. Given that the mechanisms between the sympathetic nervous system and the kidney play an important role in blood regulation, renal denervation (RDN) has emerged as a therapeutic potential in resistant hypertension. In this study, we investigated the effects of RDN on the biomechanical response and microstructure of elastic arteries. Common carotid arteries (CCA) excised from 3-month, 8-month, and 8-month denervated rats were subjected to biaxial extension-inflation test. Our results showed that hypertension developed in the 8-month-old rats. The sustained elevated blood pressure resulted in arterial remodeling which was manifested as a significant stress increase in both axial and circumferential directions after 8 months. RDN had a favorable impact on CCAs with a restoration of stresses in values similar to control arteries at 3 months. After biomechanical testing, arteries were imaged under a multi-photon microscope to identify microstructural changes in extracellular matrix (ECM). Quantification of multi-photon images showed no significant alterations of the main ECM components, elastic and collagen fibers, indicating that arteries remained intact after RDN. Regardless of the experimental group, our microstructural analysis of the multi-photon images revealed that reorientation of the collagen fibers might be the main microstructural mechanism taking place during pressurization with their straightening happening during axial stretching.