Alveolar cells under mechanical stressed niche: critical contributors to pulmonary fibrosis

Abstract Pulmonary fibrosis arises from the repeated epithelial mild injuries and insufficient repair lead to over activation of fibroblasts and excessive deposition of extracellular matrix, which result in a mechanical stretched niche. However, increasing mechanical stress likely exists before the establishment of fibrosis since early micro injuries increase local vascular permeability and prompt cytoskeletal remodeling which alter cellular mechanical forces. It is noteworthy that COVID-19 patients with severe hypoxemia will receive mechanical ventilation as supportive treatment and subsequent pathology studies indicate lung fibrosis pattern. At advanced stages, mechanical stress originates mainly from the stiff matrix since boundaries between stiff and compliant parts of the tissue could generate mechanical stress. Therefore, mechanical stress has a significant role in the whole development process of pulmonary fibrosis. The alveoli are covered by abundant capillaries and function as the main gas exchange unit. Constantly subject to variety of damages, the alveolar epithelium injuries were recently recognized to play a vital role in the onset and development of idiopathic pulmonary fibrosis. In this review, we summarize the literature regarding the effects of mechanical stress on the fundamental cells constituting the alveoli in the process of pulmonary fibrosis, particularly on epithelial cells, capillary endothelial cells, fibroblasts, mast cells, macrophages and stem cells. Finally, we briefly review this issue from a more comprehensive perspective: the metabolic and epigenetic regulation.

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Pathological Roles and Clinical Usefulness of Periostin in Type 2 Inflammation and Pulmonary Fibrosis

Biomolecules ◽

10.3390/biom11081084 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1084

Author(s):

Junya Ono ◽

Masayuki Takai ◽

Ayami Kamei ◽

Yoshinori Azuma ◽

Kenji Izuhara

Keyword(s):

Pulmonary Fibrosis ◽

Transforming Growth Factor ◽

Biological Fluids ◽

Allergic Inflammation ◽

Transforming Growth Factor Β ◽

Serum Levels ◽

Vital Role ◽

Interleukin 4 ◽

Type 2 Inflammation

Periostin is known to be a useful biomarker for various diseases. In this article, we focus on allergic diseases and pulmonary fibrosis, for which we and others are now developing detection systems for periostin as a biomarker. Biomarker-based precision medicine in the management of type 2 inflammation and fibrotic diseases since heterogeneity is of utmost importance. Periostin expression is induced by type 2 cytokines (interleukin-4/-13) or transforming growth factor-β, and plays a vital role in the pathogenesis of allergic inflammation or interstitial lung disease, respectively, andits serum levels are correlated disease severity, prognosis and responsiveness to the treatment. We first summarise the importance of type 2 biomarker and then describe the pathological role of periostin in the development and progression of type 2 allergic inflammation and pulmonary fibrosis. In addition, then, we summarise the recent development of assay methods for periostin detection, and analyse the diseases in which periostin concentration is elevated in serum and local biological fluids and its usefulness as a biomarker. Furthermore, we describe recent findings of periostin as a biomarker in the use of biologics or anti-fibrotic therapy. Finally, we describe the factors that influence the change in periostin concentration under the healthy conditions.

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Cross-species integration of single-cell RNA-seq resolved alveolar-epithelial transitional states in idiopathic pulmonary fibrosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00594.2020 ◽

2021 ◽

Author(s):

Kevin Y. Huang ◽

Enrico Petretto

Keyword(s):

Idiopathic Pulmonary Fibrosis ◽

Pulmonary Fibrosis ◽

Single Cell ◽

Transitional Cell ◽

Notch Pathway ◽

Alveolar Epithelium ◽

State Transitions ◽

Specific Cell ◽

Differentiation Process ◽

Cell State

Single-cell transcriptomics analyses of the fibrotic lung uncovered two cell states critical to lung injury recovery in the alveolar epithelium- a reparative transitional cell state in the mouse and a disease-specific cell state (KRT5-/KRT17+) in human idiopathic pulmonary fibrosis (IPF). The murine transitional cell state lies between the differentiation from type 2 (AT2) to type 1 pneumocyte (AT1), and the human KRT5-/KRT17+ cell state may arise from the dysregulation of this differentiation process. We review major findings of single-cell transcriptomics analyses of the fibrotic lung and re-analyzed data from 7 single-cell RNA sequencing studies of human and murine models of IPF, focusing on the alveolar epithelium. Our comparative and cross-species single-cell transcriptomics analyses allowed us to further delineate the differentiation trajectories from AT2 to AT1 and AT2 to the KRT5-/KRT17+ cell state. We observed AT1 cells in human IPF retain the transcriptional signature of the murine transitional cell state. Using pseudotime analysis, we recapitulated the differentiation trajectories from AT2 to AT1 and from AT2 to KRT5-/KRT17+ cell state in multiple human IPF studies. We further delineated transcriptional programs underlying cell state transitions and determined the molecular phenotypes at terminal differentiation. We hypothesize that in addition to the reactivation of developmental programs (SOX4, SOX9), senescence (TP63, SOX4) and the Notch pathway (HES1) are predicted to steer intermediate progenitors to the KRT5-/KRT17+ cell state. Our analyses suggest that activation of SMAD3 later in the differentiation process may explain the fibrotic molecular phenotype typical of KRT5-/KRT17+ cells.

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Pulmonary Stretch and Lung Mechanotransduction: Implications for Progression in the Fibrotic Lung

International Journal of Molecular Sciences ◽

10.3390/ijms22126443 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6443

Author(s):

Alessandro Marchioni ◽

Roberto Tonelli ◽

Stefania Cerri ◽

Ivana Castaniere ◽

Dario Andrisani ◽

...

Keyword(s):

Pulmonary Fibrosis ◽

Spontaneous Breathing ◽

Elastic Limit ◽

Physiological Stress ◽

Fibrous Tissue ◽

Ventilatory Support ◽

Biological Response ◽

Alveolar Epithelium ◽

Strain Curve ◽

Mechanical Forces

Lung fibrosis results from the synergic interplay between regenerative deficits of the alveolar epithelium and dysregulated mechanisms of repair in response to alveolar and vascular damage, which is followed by progressive fibroblast and myofibroblast proliferation and excessive deposition of the extracellular matrix. The increased parenchymal stiffness of fibrotic lungs significantly affects respiratory mechanics, making the lung more fragile and prone to non-physiological stress during spontaneous breathing and mechanical ventilation. Given their parenchymal inhomogeneity, fibrotic lungs may display an anisotropic response to mechanical stresses with different regional deformations (micro-strain). This behavior is not described by the standard stress–strain curve but follows the mechano-elastic models of “squishy balls”, where the elastic limit can be reached due to the excessive deformation of parenchymal areas with normal elasticity that are surrounded by inelastic fibrous tissue or collapsed induration areas, which tend to protrude outside the fibrous ring. Increasing evidence has shown that non-physiological mechanical forces applied to fibrotic lungs with associated abnormal mechanotransduction could favor the progression of pulmonary fibrosis. With this review, we aim to summarize the state of the art on the relation between mechanical forces acting on the lung and biological response in pulmonary fibrosis, with a focus on the progression of damage in the fibrotic lung during spontaneous breathing and assisted ventilatory support.

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Mercury Exposure and Endothelial Dysfunction

International Journal of Toxicology ◽

10.1177/1091581815589766 ◽

2015 ◽

Vol 34 (4) ◽

pp. 300-307 ◽

Cited By ~ 13

Author(s):

Swati Omanwar ◽

M. Fahim

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Endothelial Dysfunction ◽

Vascular Endothelium ◽

Circulatory System ◽

Vital Role ◽

Mercury Exposure ◽

And Function ◽

The Impact ◽

And Oxidative Stress

Vascular endothelium plays a vital role in the organization and function of the blood vessel and maintains homeostasis of the circulatory system and normal arterial function. Functional disruption of the endothelium is recognized as the beginning event that triggers the development of consequent cardiovascular disease (CVD) including atherosclerosis and coronary heart disease. There is a growing data associating mercury exposure with endothelial dysfunction and higher risk of CVD. This review explores and evaluates the impact of mercury exposure on CVD and endothelial function, highlighting the interplay of nitric oxide and oxidative stress.

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Pseudogene ACTBP2 increases blood–brain barrier permeability by promoting KHDRBS2 transcription through recruitment of KMT2D/WDR5 in Aβ1–42 microenvironment

Cell Death Discovery ◽

10.1038/s41420-021-00531-y ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Qianshuo Liu ◽

Xiaobai Liu ◽

Defeng Zhao ◽

Xuelei Ruan ◽

Rui Su ◽

...

Keyword(s):

Blood Brain Barrier ◽

Molecular Mechanisms ◽

Rna Binding ◽

Vital Role ◽

Brain Barrier ◽

Blood Brain ◽

Bbb Permeability ◽

Novel Target ◽

And Function

AbstractThe blood–brain barrier (BBB) has a vital role in maintaining the homeostasis of the central nervous system (CNS). Changes in the structure and function of BBB can accelerate Alzheimer’s disease (AD) development. β-Amyloid (Aβ) deposition is the major pathological event of AD. We elucidated the function and possible molecular mechanisms of the effect of pseudogene ACTBP2 on the permeability of BBB in Aβ1–42 microenvironment. BBB model treated with Aβ1–42 for 48 h were used to simulate Aβ-mediated BBB dysfunction in AD. We proved that pseudogene ACTBP2, RNA-binding protein KHDRBS2, and transcription factor HEY2 are highly expressed in ECs that were obtained in a BBB model in vitro in Aβ1–42 microenvironment. In Aβ1–42-incubated ECs, ACTBP2 recruits methyltransferases KMT2D and WDR5, binds to KHDRBS2 promoter, and promotes KHDRBS2 transcription. The interaction of KHDRBS2 with the 3′UTR of HEY2 mRNA increases the stability of HEY2 and promotes its expression. HEY2 increases BBB permeability in Aβ1–42 microenvironment by transcriptionally inhibiting the expression of ZO-1, occludin, and claudin-5. We confirmed that knocking down of Khdrbs2 or Hey2 increased the expression levels of ZO-1, occludin, and claudin-5 in APP/PS1 mice brain microvessels. ACTBP2/KHDRBS2/HEY2 axis has a crucial role in the regulation of BBB permeability in Aβ1–42 microenvironment, which may provide a novel target for the therapy of AD.

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Kinematic Design of Functional Nanoscale Mechanisms From Molecular Primitives

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4051472 ◽

2021 ◽

Author(s):

Meysam T. Chorsi ◽

Pouya Tavousi ◽

Caitlyn Mundrane ◽

Vitaliy Gorbatyuk ◽

Kazem Kazerounian ◽

...

Keyword(s):

Ion Channels ◽

Range Of Motion ◽

Systematic Approach ◽

Design Space ◽

Vital Role ◽

Degree Of Freedom ◽

Living Systems ◽

Kinematic Design ◽

Systematic Exploration ◽

And Function

Abstract Natural nanomechanisms such as capillaries, neurotransmitters, and ion channels play a vital role in the living systems. But the design principles developed by nature through evolution are not well understood and, hence, not applicable to engineered nanomachines. Thus, the design of nanoscale mechanisms with prescribed functions remains a challenge. Here, we present a systematic approach based on established kinematics techniques to designing, analyzing, and controlling manufacturable nanomachines with prescribed mobility and function built from a finite but extendable number of available "molecular primitives." Our framework allows the systematic exploration of the design space of irreducibly simple nanomachines, built with prescribed motion specification by combining available nanocomponents into systems having constrained, and consequently controllable motions. We show that the proposed framework has allowed us to discover and verify a molecule in the form of a seven link, seven revolute (7R) close loop spatial linkage with mobility (degree of freedom) of one. Furthermore, our experiments exhibit the type and range of motion predicted by our simulations. Enhancing such a structure into functional nanomechanisms by exploiting and controlling their motions individually or as part of an ensemble could galvanize development of the multitude of engineering, scientific, medical, and consumer applications that can benefit from engineered nanomachines.

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The Relationship between the Community Structure and Function of Bacterioplankton and the Environmental Response in Qingcaosha Reservoir

Water ◽

10.3390/w13223155 ◽

2021 ◽

Vol 13 (22) ◽

pp. 3155

Author(s):

Shumin Liu ◽

Fengbin Zhao ◽

Xin Fang

Keyword(s):

Water Quality ◽

Community Structure ◽

High Throughput Sequencing ◽

Scientific Basis ◽

Vital Role ◽

Structure And Function ◽

Environmental Response ◽

Temporal And Spatial ◽

Density And Biomass ◽

And Function

Phytoplankton and bacterioplankton play a vital role in the structure and function of aquatic ecosystems, and their activity is closely linked to water eutrophication. However, few researchers have considered the temporal and spatial succession of phytoplankton and bacterioplankton, and their responses to environmental factors. The temporal and spatial succession of bacterioplankton and their ecological interaction with phytoplankton and water quality were analyzed using 16S rDNA high-throughput sequencing for their identification, and the functions of bacterioplankton were predicted. The results showed that the dominant classes of bacterioplankton in the Qingcaosha Reservoir were Gammaproteobacteria, Alphaproteobacteria, Actinomycetes, Acidimicrobiia, and Cyanobacteria. In addition, the Shannon diversity indexes were compared, and the results showed significant temporal differences based on monthly averaged value, although no significant spatial difference. The community structure was found to be mainly influenced by phytoplankton density and biomass, dissolved oxygen, and electrical conductivity. The presence of Pseudomonas and Legionella was positively correlated with that of Pseudanabaena sp., and Sphingomonas and Paragonimus with Melosira granulata. On the contrary, the presence of Planctomycetes was negatively correlated with Melosira granulata, as was Deinococcus-Thermus with Cyclotella sp. The relative abundance of denitrifying bacteria decreased from April to December, while the abundance of nitrogen-fixing bacteria increased. This study provides a scientific basis for understanding the ecological interactions between bacteria, algae, and water quality in reservoir ecosystems.

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Integrin β4 as a Potential Diagnostic and Therapeutic Tumor Marker

Biomolecules ◽

10.3390/biom11081197 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1197

Author(s):

Haoyu Yang ◽

Zixuan Xu ◽

Yuqian Peng ◽

Jiali Wang ◽

Yang Xiang

Keyword(s):

Signal Transduction ◽

Tumor Marker ◽

Tumor Invasion ◽

Epithelial Mesenchymal Transition ◽

Vital Role ◽

Structure And Function ◽

Mesenchymal Transition ◽

Tumor Tissues ◽

Integrin Β4 ◽

And Function

Integrin β4 (ITGβ4) is a class of transmembrane adhesion molecules composed of hemidesmosomes (HDs). Its unique long intracellular domain provides intricate signal transduction functions. These signal transduction effects are especially prominent in tumors. Many recent studies have shown that integrin β4 is differentially expressed in various tumors, and it plays a vital role in tumor invasion, proliferation, epithelial–mesenchymal transition, and angiogenesis. Therefore, we categorize the research related to integrin β4, starting from its structure and function in tumor tissues, and provide a basic description. Based on its structure and function, we believe that integrin β4 can be used as a tumor marker. In clinical practice, it is described as a diagnostic marker for the targeted treatment of cancer and will be helpful in the clinical diagnosis and treatment of tumors.

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Epithelial–Mesenchymal Transition in the Pathogenesis of Idiopathic Pulmonary Fibrosis

Medicina ◽

10.3390/medicina55040083 ◽

2019 ◽

Vol 55 (4) ◽

pp. 83 ◽

Cited By ~ 23

Author(s):

Francesco Salton ◽

Maria Volpe ◽

Marco Confalonieri

Keyword(s):

Epithelial Cells ◽

Idiopathic Pulmonary Fibrosis ◽

Pulmonary Fibrosis ◽

Epithelial Mesenchymal Transition ◽

Treatment Options ◽

Alveolar Epithelium ◽

Alveolar Epithelial Cells ◽

Mesenchymal Transition ◽

Alveolar Epithelial ◽

Serious Disease

Idiopathic pulmonary fibrosis (IPF) is a serious disease of the lung, which leads to extensive parenchymal scarring and death from respiratory failure. The most accepted hypothesis for IPF pathogenesis relies on the inability of the alveolar epithelium to regenerate after injury. Alveolar epithelial cells become apoptotic and rare, fibroblasts/myofibroblasts accumulate and extracellular matrix (ECM) is deposited in response to the aberrant activation of several pathways that are physiologically implicated in alveologenesis and repair but also favor the creation of excessive fibrosis via different mechanisms, including epithelial–mesenchymal transition (EMT). EMT is a pathophysiological process in which epithelial cells lose part of their characteristics and markers, while gaining mesenchymal ones. A role for EMT in the pathogenesis of IPF has been widely hypothesized and indirectly demonstrated; however, precise definition of its mechanisms and relevance has been hindered by the lack of a reliable animal model and needs further studies. The overall available evidence conceptualizes EMT as an alternative cell and tissue normal regeneration, which could open the way to novel diagnostic and prognostic biomarkers, as well as to more effective treatment options.

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An overview of advanced biocompatible and biomimetic materials for creation of replacement structures in the musculoskeletal systems: focusing on cartilage tissue engineering

Journal of Biological Engineering ◽

10.1186/s13036-019-0209-9 ◽

2019 ◽

Vol 13 (1) ◽

Cited By ~ 8

Author(s):

Azizeh Rahmani Del Bakhshayesh ◽

Nahideh Asadi ◽

Alireza Alihemmati ◽

Hamid Tayefi Nasrabadi ◽

Azadeh Montaseri ◽

...

Keyword(s):

Tissue Engineering ◽

Cartilage Tissue Engineering ◽

Interdisciplinary Approach ◽

Culture Conditions ◽

Vital Role ◽

Cartilage Tissue ◽

Biomimetic Materials ◽

Musculoskeletal Tissue ◽

And Function

Abstract Tissue engineering, as an interdisciplinary approach, is seeking to create tissues with optimal performance for clinical applications. Various factors, including cells, biomaterials, cell or tissue culture conditions and signaling molecules such as growth factors, play a vital role in the engineering of tissues. In vivo microenvironment of cells imposes complex and specific stimuli on the cells, and has a direct effect on cellular behavior, including proliferation, differentiation and extracellular matrix (ECM) assembly. Therefore, to create appropriate tissues, the conditions of the natural environment around the cells should be well imitated. Therefore, researchers are trying to develop biomimetic scaffolds that can produce appropriate cellular responses. To achieve this, we need to know enough about biomimetic materials. Scaffolds made of biomaterials in musculoskeletal tissue engineering should also be multifunctional in order to be able to function better in mechanical properties, cell signaling and cell adhesion. Multiple combinations of different biomaterials are used to improve above-mentioned properties of various biomaterials and to better imitate the natural features of musculoskeletal tissue in the culture medium. These improvements ultimately lead to the creation of replacement structures in the musculoskeletal system, which are closer to natural tissues in terms of appearance and function. The present review article is focused on biocompatible and biomimetic materials, which are used in musculoskeletal tissue engineering, in particular, cartilage tissue engineering.

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