Extracellular Matrix as a Driver of Chronic Lung Diseases

Collagen deposition in lung parenchyma driven by depletion of interstitial Lyve-1+ macrophages prevents cigarette smoke-induced emphysema and loss of airway function

Introduction

Collagen is essential for maintaining lung structure and function and its remodeling has been associated with respiratory diseases including chronic obstructive pulmonary disease (COPD). However, the cellular mechanisms driving collagen remodeling and the functional implications of this process in the pathophysiology of pulmonary diseases remain poorly understood.

Methods

To address this question, we employed Lyve1wt/cre ; Csf1rflox/flox mice with specific depletion of Lyve-1+ macrophages and assessed the content, types and organization of collagen in lung compartments at steady state and after chronic exposure to cigarette smoke (CS).

Results

Using this mouse model, we found that the absence of this subpopulation of tissue resident macrophage led to the deposition of type I collagen fibers around the alveoli and bronchi at steady state. Further analysis by polarized light microscopy and Sircol collagen assay revealed that the collagen fibers accumulating in the lungs depleted of Lyve-1+ macrophages were thicker and crosslinked. A decrease in MMP-9 gene expression and proteolytic activity together with an increase in Col1a1, Timp-3 and Lox expression accompanied the collagen alterations. Next, we investigated the effect of the collagen remodeling on the pathophysiology of COPD and airway function in mice lacking Lyve-1+ macrophages exposed chronically to cigarette smoke (CS), a well-established animal model of COPD. We found that deposition of collagen prior CS exposure protected these mice against destruction of alveoli (emphysema), and bronchi thickening and prevented loss of airway function.

Discussion

Thus, we uncover that interstitial Lyve-1+ macrophages regulate the composition, amount, and architecture of collagen network in the lungs at steady state and that such collagen remodeling functionally impacts the development of COPD. This study further supports the potential of targeting collagen as promising approaches to treat respiratory diseases.

Nanoparticles to target asthma

Asthma is a heterogeneous chronic lung disease that affects nearly 340 million people globally. Airway hyperresponsiveness, remodeling (thickening and fibrosis), and mucus hypersecretion are some hallmarks of asthma. With several current treatments having serious side effects from long-term use and a proportion of patients with uncontrolled asthma, there is an urgent need for new therapies. With an increasing understanding of asthma pathophysiology, there is a recognized need to target therapies to specific cell types of the airway, which necessitates the identification of delivery systems that can overcome increased mucus and thickened airways. Nanoparticles (NPs) that are highly customizable (material, size, charge, and surface modification) are a potential solution for delivery systems of a wide variety of cargoes (nucleic acids, proteins, and/or small molecules), as well as sole therapeutics for asthma. However, there is a need to consider the safety of the NPs in terms of potential for inflammation, toxicity, nonspecific targets, and accumulation in organs. Ongoing clinical trials using NPs, some FDA-approved for therapeutics in other diseases, provide confidence regarding the potential safety and efficacy of NPs in asthma treatment. This review highlights the current state of the use of NPs in asthma, identifying opportunities for further improvements in NP design and utilization for targeting this chronic lung disease.

Cancer treatments as paradoxical catalysts of tumor awakening in the lung

Much of the fatality of tumors is linked to the growth of metastases, which can emerge months to years after apparently successful treatment of primary tumors. Metastases arise from disseminated tumor cells (DTCs), which disperse through the body in a dormant state to seed distant sites. While some DTCs lodge in pre-metastatic niches (PMNs) and rapidly develop into metastases, other DTCs settle in distinct microenvironments that maintain them in a dormant state. Subsequent awakening, induced by changes in the microenvironment of the DTC, causes outgrowth of metastases. Hence, there has been extensive investigation of the factors causing survival and subsequent awakening of DTCs, with the goal of disrupting these processes to decrease cancer lethality. We here provide a detailed overview of recent developments in understanding of the factors controlling dormancy and awakening in the lung, a common site of metastasis for many solid tumors. These factors include dynamic interactions between DTCs and diverse epithelial, mesenchymal, and immune cell populations resident in the lung. Paradoxically, among key triggers for metastatic outgrowth, lung tissue remodeling arising from damage induced by the treatment of primary tumors play a significant role. In addition, growing evidence emphasizes roles for inflammation and aging in opposing the factors that maintain dormancy. Finally, we discuss strategies being developed or employed to reduce the risk of metastatic recurrence.

WISP1 and Macrophage Migration Inhibitory Factor in Respiratory Inflammation: Novel Insights and Therapeutic Potentials for Asthma and COPD

Recent advancements highlight the intricate interplay between the extracellular matrix (ECM) and immune responses, notably in respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD). The ECM, a dynamic structural framework within tissues, orches-trates a plethora of cellular processes, including immune cell behavior and tissue repair mecha-nisms. WNT1-inducible-signaling pathway protein 1 (WISP1), a key ECM regulator, controls immune cell behavior, cytokine production, and tissue repair by modulating integrins, PI3K, Akt, β-catenin, and mTOR signaling pathways. WISP1 also induces macrophage migration inhibitory factor (MIF) expression via Src kinases and epidermal growth factor receptor (EGFR) activation. MIF, through its wide range of activities, enhances inflammation and tissue restructuring. Rec-ognized for its versatile roles in regulating the immune system, MIF interacts with multiple immune components, such as the NLRP3 inflammasome, thereby sustaining inflammatory pro-cesses. The WISP1-MIF axis potentially unveils complex molecular mechanisms governing im-mune responses and inflammation. Understanding the intricate roles of WISP1 and MIF in the pathogenesis of chronic respiratory diseases such as asthma and COPD could lead to the identi-fication of novel targets for therapeutic intervention to alleviate disease severity and enhance patient outcomes.

Stem cells, cell therapies, and bioengineering in lung biology and diseases 2023

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

Targeting lysyl oxidase like 2 attenuates OVA-induced airway remodeling partly via the AKT signaling pathway

BACKGROUND

Airway epithelium is an important component of airway structure and the initiator of airway remodeling in asthma. The changes of extracellular matrix (ECM), such as collagen deposition and structural disturbance, are typical pathological features of airway remodeling. Thus, identifying key mediators that derived from airway epithelium and capable of modulating ECM may provide valuable insights for targeted therapy of asthma.

METHODS

The datasets from Gene Expression Omnibus database were analyzed to screen differentially expressed genes in airway epithelium of asthma. We collected bronchoscopic biopsies and serum samples from asthmatic and healthy subjects to assess lysyl oxidase like 2 (LOXL2) expression. RNA sequencing and various experiments were performed to determine the influences of LOXL2 knockdown in ovalbumin (OVA)-induced mouse models. The roles and mechanisms of LOXL2 in bronchial epithelial cells were explored using LOXL2 small interfering RNA, overexpression plasmid and AKT inhibitor.

RESULTS

Both bioinformatics analysis and further experiments revealed that LOXL2 is highly expressed in airway epithelium of asthmatics. In vivo, LOXL2 knockdown significantly inhibited OVA-induced ECM deposition and epithelial-mesenchymal transition (EMT) in mice. In vitro, the transfection experiments on 16HBE cells demonstrated that LOXL2 overexpression increases the expression of N-cadherin and fibronectin and reduces the expression of E-cadherin. Conversely, after silencing LOXL2, the expression of E-cadherin is up-regulated. In addition, the remodeling and EMT process that induced by transforming growth factor-β1 could be enhanced and weakened after LOXL2 overexpression and silencing in 16HBE cells. Combining the RNA sequencing of mouse lung tissues and experiments in vitro, LOXL2 was involved in the regulation of AKT signaling pathway. Moreover, the treatment with AKT inhibitor in vitro partially alleviated the consequences associated with LOXL2 overexpression.

CONCLUSIONS

Taken together, the results demonstrated that epithelial LOXL2 plays a role in asthmatic airway remodeling partly via the AKT signaling pathway and highlighted the potential of LOXL2 as a therapeutic target for airway remodeling in asthma.

The role and regulation of SIRT1 in pulmonary fibrosis

Pulmonary fibrosis (PF) is a progressive and fatal lung disease with high incidence and a lack of effective treatment, which is a severe public health problem. PF has caused a huge socio-economic burden, and its pathogenesis has become a research hotspot. SIRT1 is a nicotinamide adenosine dinucleotide (NAD)-dependent sirtuin essential in tumours, Epithelial mesenchymal transition (EMT), and anti-aging. Numerous studies have demonstrated after extensive research that it is crucial in preventing the progression of pulmonary fibrosis. This article reviews the biological roles and mechanisms of SIRT1 in regulating the progression of pulmonary fibrosis in terms of EMT, oxidative stress, inflammation, aging, autophagy, and discusses the potential of SIRT1 as a therapeutic target for pulmonary fibrosis, and provides a new perspective on therapeutic drugs and prognosis prospects.