Pulmonary fibroblasts from COPD patients show an impaired response of elastin synthesis to TGF-β1

DNA nanoparticles targeting FOXO4 selectively eliminate cigarette smoke-induced senescent lung fibroblasts

The pathogenesis and development of chronic obstructive pulmonary disease (COPD) are significantly related to cellular senescence. Strategies to eliminate senescent cells have been confirmed to benefit several senescence-related diseases. However, there are few reports of senolytic drugs in COPD management. In this study, we demonstrated elevated FOXO4 expression in cigarette smoke-induced senescent lung fibroblasts both in vitro and in vivo. Additionally, self-assembled DNA nanotubes loaded with single-stranded FOXO4 siRNA (siFOXO4-NT) were designed and synthesized to knockdown FOXO4 in senescent fibroblasts. We found that siFOXO4-NT can concentration- and time-dependently enter human lung fibroblasts (HFL-1 cells), thereby reducing FOXO4 levels in vitro. Most importantly, siFOXO4-NT selectively cleared senescent HFL-1 cells by reducing BCLXL expression and the BCL2/BAX ratio, which were increased in CSE-induced senescent HFL-1 cells. The findings from our work present a novel strategy for senolytic drug development for COPD therapy.

A Single-Cell Atlas of Small Airway Disease in Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

Rationale: Emerging data demonstrate that the smallest conducting airways, terminal bronchioles, are the early site of tissue destruction in chronic obstructive pulmonary disease (COPD) and are reduced by as much as 41% by the time someone is diagnosed with mild (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 1) COPD. Objectives: To develop a single-cell atlas that describes the structural, cellular, and extracellular matrix alterations underlying terminal bronchiole loss in COPD. Methods: This cross-sectional study of 262 lung samples derived from 34 ex-smokers with normal lung function (n = 10) or GOLD stage 1 (n = 10), stage 2 (n = 8), or stage 4 (n = 6) COPD was performed to assess the morphology, extracellular matrix, single-cell atlas, and genes associated with terminal bronchiole reduction using stereology, micro-computed tomography, nonlinear optical microscopy, imaging mass spectrometry, and transcriptomics. Measurements and Main Results: The lumen area of terminal bronchioles progressively narrows with COPD severity as a result of the loss of elastin fibers within alveolar attachments, which was observed before microscopic emphysematous tissue destruction in GOLD stage 1 and 2 COPD. The single-cell atlas of terminal bronchioles in COPD demonstrated M1-like macrophages and neutrophils located within alveolar attachments and associated with the pathobiology of elastin fiber loss, whereas adaptive immune cells (naive, CD4, and CD8 T cells, and B cells) are associated with terminal bronchiole wall remodeling. Terminal bronchiole pathology was associated with the upregulation of genes involved in innate and adaptive immune responses, the interferon response, and the degranulation of neutrophils. Conclusions: This comprehensive single-cell atlas highlights terminal bronchiole alveolar attachments as the initial site of tissue destruction in centrilobular emphysema and an attractive target for disease modification.

Organotypic whole hemisphere brain slice models to study the effects of donor age and oxygen-glucose-deprivation on the extracellular properties of cortical and striatal tissue

BACKGROUND

The brain extracellular environment is involved in many critical processes associated with neurodevelopment, neural function, and repair following injury. Organization of the extracellular matrix and properties of the extracellular space vary throughout development and across different brain regions, motivating the need for platforms that provide access to multiple brain regions at different stages of development. We demonstrate the utility of organotypic whole hemisphere brain slices as a platform to probe regional and developmental changes in the brain extracellular environment. We also leverage whole hemisphere brain slices to characterize the impact of cerebral ischemia on different regions of brain tissue.

RESULTS

Whole hemisphere brain slices taken from postnatal (P) day 10 and P17 rats retained viable, metabolically active cells through 14 days in vitro (DIV). Oxygen-glucose-deprivation (OGD), used to model a cerebral ischemic event in vivo, resulted in reduced slice metabolic activity and elevated cell death, regardless of slice age. Slices from P10 and P17 brains showed an oligodendrocyte and microglia-driven proliferative response after OGD exposure, higher than the proliferative response seen in DIV-matched normal control slices. Multiple particle tracking in oxygen-glucose-deprived brain slices revealed that oxygen-glucose-deprivation impacts the extracellular environment of brain tissue differently depending on brain age and brain region. In most instances, the extracellular space was most difficult to navigate immediately following insult, then gradually provided less hindrance to extracellular nanoparticle diffusion as time progressed. However, changes in diffusion were not universal across all brain regions and ages.

CONCLUSIONS

We demonstrate whole hemisphere brain slices from P10 and P17 rats can be cultured up to two weeks in vitro. These brain slices provide a viable platform for studying both normal physiological processes and injury associated mechanisms with control over brain age and region. Ex vivo OGD impacted cortical and striatal brain tissue differently, aligning with preexisting data generated in in vivo models. These data motivate the need to account for both brain region and age when investigating mechanisms of injury and designing potential therapies for cerebral ischemia.

Resident interstitial lung fibroblasts and their role in alveolar stem cell niche development, homeostasis, injury, and regeneration

Developing, regenerating, and repairing a lung all require interstitial resident fibroblasts (iReFs) to direct the behavior of the epithelial stem cell niche. During lung development, distal lung fibroblasts, in the form of matrix-, myo-, and lipofibroblasts, form the extra cellular matrix (ECM), create tensile strength, and support distal epithelial differentiation, respectively. During de novo septation in a murine pneumonectomy lung regeneration model, developmental processes are reactivated within the iReFs, indicating progenitor function well into adulthood. In contrast to the regenerative activation of fibroblasts upon acute injury, chronic injury results in fibrotic activation. In murine lung fibrosis models, fibroblasts can pathologically differentiate into lineages beyond their normal commitment during homeostasis. In lung injury, recently defined alveolar niche cells support the expansion of alveolar epithelial progenitors to regenerate the epithelium. In human fibrotic lung diseases like bronchopulmonary dysplasia (BPD), idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD), dynamic changes in matrix-, myo-, lipofibroblasts, and alveolar niche cells suggest differential requirements for injury pathogenesis and repair. In this review, we summarize the role of alveolar fibroblasts and their activation stage in alveolar septation and regeneration and incorporate them into the context of human lung disease, discussing fibroblast activation stages and how they contribute to BPD, IPF, and COPD.

Lung regeneration: implications of the diseased niche and ageing

Most chronic and acute lung diseases have no cure, leaving lung transplantation as the only option. Recent work has improved our understanding of the endogenous regenerative capacity of the lung and has helped identification of different progenitor cell populations, as well as exploration into inducing endogenous regeneration through pharmaceutical or biological therapies. Additionally, alternative approaches that aim at replacing lung progenitor cells and their progeny through cell therapy, or whole lung tissue through bioengineering approaches, have gained increasing attention. Although impressive progress has been made, efforts at regenerating functional lung tissue are still ineffective. Chronic and acute lung diseases are most prevalent in the elderly and alterations in progenitor cells with ageing, along with an increased inflammatory milieu, present major roadblocks for regeneration. Multiple cellular mechanisms, such as cellular senescence and mitochondrial dysfunction, are aberrantly regulated in the aged and diseased lung, which impairs regeneration. Existing as well as new human in vitro models are being developed, improved and adapted in order to study potential mechanisms of lung regeneration in different contexts. This review summarises recent advances in understanding endogenous as well as exogenous regeneration and the development of in vitro models for studying regenerative mechanisms.

Pentagalloyl glucose increases elastin deposition, decreases reactive oxygen species and matrix metalloproteinase activity in pulmonary fibroblasts under inflammatory conditions

Emphysema is characterized by degradation of lung alveoli that leads to poor airflow in lungs. Irreversible elastic fiber degradation by matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) activity leads to loss of elasticity and drives the progression of this disease. We investigated if a polyphenol, pentagalloyl glucose (PGG) can increase elastin production in pulmonary fibroblasts. We also studied the effect of PGG treatment in reducing MMP activity and ROS levels in cells. We exposed rat pulmonary fibroblasts to two different types of inflammatory environments i.e., tumor necrosis factor-α (TNF-α) and cigarette smoke extract (CSE) to mimic the disease. Parameters like lysyl oxidase (LOX) and elastin gene expression, MMP-9 activity in the medium, lysyl oxidase (LOX) activity and ROS levels were studied to assess the effect of PGG on pulmonary fibroblasts. CSE inhibited lysyl oxidase (LOX) enzyme activity that resulted in a decreased elastin formation. Similarly, TNF-α treated cells showed less elastin in the cell layers. Both these agents caused increase in MMP activity and ROS levels in cells. However, when supplemented with PGG treatment along with these two inflammatory agents, we saw a significant increase in elastin deposition, reduction in both MMP activity and ROS levels. Thus PGG, which has anti-inflammatory, anti-oxidant properties coupled with its ability to aid in elastic fiber formation, can be a multifunctional drug to potentially arrest the progression of emphysema.

p53 Signaling Pathway Polymorphisms Associated With Emphysematous Changes in Patients With COPD

BACKGROUND

The p53 signaling pathway may be important for the pathogenesis of emphysematous changes in the lungs of smokers. Polymorphism of p53 at codon 72 is known to affect apoptotic effector proteins, and the polymorphism of mouse double minute 2 homolog (MDM2) single nucleotide polymorphism (SNP)309 is known to increase MDM2 expression. The aim of this study was to assess polymorphisms of the p53 and MDM2 genes in smokers and confirm the role of SNPs in these genes in the pathogenesis of pulmonary emphysema.

METHODS

This study included 365 patients with a smoking history, and the polymorphisms of p53 and MDM2 genes were identified. The degree of pulmonary emphysema was determined by means of CT scanning. SNPs, MDM2 mRNA, and p53 protein levels were assessed in human lung tissues from smokers. Plasmids encoding p53 and MDM2 SNPs were used to transfect human lung fibroblasts (HLFs) with or without cigarette smoke extract (CSE), and the effects on cell proliferation and MDM2 promoter activity were measured.

RESULTS

The polymorphisms of the p53 and MDM2 genes were associated with emphysematous changes in the lung and were also associated with p53 protein and MDM2 mRNA expression in the lung tissue samples. Transfection with a p53 gene-coding plasmid regulated HLF proliferation, and the analysis of P2 promoter activity in MDM2 SNP309-coding HLFs showed the promoter activity was altered by CSE.

CONCLUSIONS

Our data demonstrated that p53 and MDM2 gene polymorphisms are associated with apoptotic signaling and smoking-related emphysematous changes in lungs from smokers.

Multiple applications of Alamar Blue as an indicator of metabolic function and cellular health in cell viability bioassays

Accurate prediction of the adverse effects of test compounds on living systems, detection of toxic thresholds, and expansion of experimental data sets to include multiple toxicity end-point analysis are required for any robust screening regime. Alamar Blue is an important redox indicator that is used to evaluate metabolic function and cellular health. The Alamar Blue bioassay has been utilized over the past 50 years to assess cell viability and cytotoxicity in a range of biological and environmental systems and in a number of cell types including bacteria, yeast, fungi, protozoa and cultured mammalian and piscine cells. It offers several advantages over other metabolic indicators and other cytotoxicity assays. However, as with any bioassay, suitability must be determined for each application and cell model. This review seeks to highlight many of the important considerations involved in assay use and design in addition to the potential pitfalls.

The effects of Ang-1, IL-8 and TGF-β1 on the pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) is a prevalent smoking-related disease for which no disease‑altering therapies currently exist. Airway remodeling is one of the most important mechanisms in the pathogenesis of COPD and is triggered by chronic inflammation mediated by angiopoietin-1 (Ang-1), interleukin-8 (IL-8) and transforming growth factor-β1 (TGF-β1). The aim of this study was to investigate the effects of Ang-1, IL-8 and TGF-β1 on the pathogenesis of COPD. Forty-two COPD patients and 10 healthy adults (group A) were included in this study. We divided the 42 patients into 4 groups (groups B-E) according to the severity of the disease. We investigated the levels of Ang-1, IL-8 and TGF-β1 and the levels of pulmonary function (PF) in the stable and acute phases of COPD by enzyme-linked immunosorbent assay. We found statistically significant differences in the expression levels of Ang-1, IL-8 and TGF-β1 between the stable and acute phases in groups B-E. We found statistically significant differences in the expression levels of Ang-1 among all groups in the stable phase. In addition, there were statistically significant differences in the expression levels of TGF-β1 among all groups. There were statistically significant differences in the expression levels of IL-8 between group A and the other groups in the stable phase. Furthermore, in groups C-E we found higher correlations between Ang-1 and the forced expiratory volume in one second of forced vital capacity (FVC) [FEV1(%)] and FEV1/FVC(%) than between TGF-β1 and FEV1(%) and FEV1/FVC(%). We conclude that the blood vessel factor is more closely related to the pathogenesis of COPD.

Effect of mitomycin C on the tensile properties of the upper lacrimal canaliculi in a rabbit model

The upper lacrimal canaliculus consists of a tubular structure, and the tensile properties which in lacrimal tissues might contribute to structural integrity and tear drainage. We evaluated the characteristics of the tensile properties of the upper lacrimal canaliculi and the clinical implications of using a mitomycin C (MMC)-treated rabbit model. Mitomycin C (0.04%) was applied to the punctum of rabbits for 5 min, and the upper lacrimal tissues including the punctum were excised and attached to a forced transducer to record the tensile properties in a resting state 1 month later. The recording showed continuing decrement of basal tension with time in the lacrimal tissues treated with MMC in contrast with normal controls which maintained initial tension throughout the experiment. The rabbits were then randomly divided into the following 3 groups: vertical punctal incision with the MMC application group; vertical punctal incision with a balanced salt solution application group; and a balanced salt solution application only group. Four weeks after surgery, the puncta of rabbits treated with an incision and MMC application were more dilated clinically and showed less elasticity as compared with the other groups. Histological staining revealed that MMC treatment combined with incision decreased the amount of collagen and elastin fibers in the canaliculi. These results suggest that lacrimal canaliculi of rabbits have rheological basal tension and elasticity, which can be decreased by the use of MMC treatment.