Neutrophil elastase-induced elastin degradation mediates macrophage influx and lung injury in 60% O2-exposed neonatal rats

A pathological joint-liver axis mediated by matrikine-activated CD4+ T cells

The knee joint has long been considered a closed system. The pathological effects of joint diseases on distant organs have not been investigated. Herein, our clinical data showed that post-traumatic joint damage, combined with joint bleeding (hemarthrosis), exhibits a worse liver function compared with healthy control. With mouse model, hemarthrosis induces both cartilage degeneration and remote liver damage. Next, we found that hemarthrosis induces the upregulation in ratio and differentiation towards Th17 cells of CD4+ T cells in peripheral blood and spleen. Deletion of CD4+ T cells reverses hemarthrosis-induced liver damage. Degeneration of cartilage matrix induced by hemarthrosis upregulates serological type II collagen (COL II), which activates CD4+ T cells. Systemic application of a COL II antibody blocks the activation. Furthermore, bulk RNAseq and single-cell qPCR analysis revealed that the cartilage Akt pathway is inhibited by blood treatment. Intra-articular application of Akt activator blocks the cartilage degeneration and thus protects against the liver impairment in mouse and pig models. Taken together, our study revealed a pathological joint-liver axis mediated by matrikine-activated CD4+ T cells, which refreshes the organ-crosstalk axis and provides a new treatment target for hemarthrosis-related disease. Intra-articular bleeding induces cartilage degradation through down-reulation of cartilage Akt pathway. During this process, the soluble COL II released from the damaged cartilage can activate peripheral CD4+ T cells, differention into Th17 cells and secretion of IL-17, which consequently induces liver impairment. Intra-articular application of sc79 (inhibitor of Akt pathway) can prevent the cartilage damage as well as its peripheral influences.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.

Pharmacotherapy for Neuromyelitis Optica Spectrum Disorders: Current Management and Future Options

Neuromyelitis optica (NMO) is an inflammatory and demyelinating disease of the central nervous system. Although the prevalence of NMO is low, the rapid and severe impairment observed in patients has led to extensive development of research in the fields of diagnostic criteria and therapy in the past 15 years. With improved understanding of the pathophysiology of NMO and the role of aquaporin-4 (AQP4) or myelin oligodendrocyte glycoprotein antibodies, numerous therapeutic approaches have been proposed and are currently undergoing evaluation. In this review, we describe the rationale for existing therapeutics and their benefit/risk ratio. We also discuss the pharmacological and clinical interest of future approaches targeting, among others, B or T cells, the blood-central nervous system barrier, complement, polynuclear cells, AQP4-antibody linkage and AQP4 activity. The numerous agents under development are the result of a major collaborative effort all over the world. After the considerable progress on diagnosis, we are now close to class I evidence for a therapeutic effect of several drugs in NMO spectrum disorders, most notably with the anti-interleukin-6 receptor antibody (satralizumab) and anti-complement-5 antibody (eculizumab).

Recent Developments in mRNA-Based Protein Supplementation Therapy to Target Lung Diseases

Protein supplementation therapy using in vitro-transcribed (IVT) mRNA for genetic diseases contains huge potential as a new class of therapy. From the early ages of synthetic mRNA discovery, a great number of studies showed the versatile use of IVT mRNA as a novel approach to supplement faulty or absent protein and also as a vaccine. Many modifications have been made to produce high expressions of mRNA causing less immunogenicity and more stability. Recent advancements in the in vivo lung delivery of mRNA complexed with various carriers encouraged the whole mRNA community to tackle various genetic lung diseases. This review gives a comprehensive overview of cells associated with various lung diseases and recent advancements in mRNA-based protein replacement therapy. This review also covers a brief summary of developments in mRNA modifications and nanocarriers toward clinical translation.

NPS 2143, a selective calcium-sensing receptor antagonist inhibits lipopolysaccharide-induced pulmonary inflammation

NPS 2143, a novel and selective antagonist of calcium-sensing receptor (CaSR) has been reported to possess anti-inflammatory activity. In the present study, we examined the protective effect of NPS 2143 on lipopolysaccharide (LPS)-induced acute lung injury (ALI). NPS 2143 pretreatment significantly inhibited the influx of inflammatory cells and the expression of monocyte chemoattractant protein-1 (MCP-1) in the lung of mice with LPS-induced ALI. NPS 2143 decreased the levels of neutrophil elastase (NE) and protein concentration in the bronchoalveolar lavage fluid (BALF). NPS 2143 also reduced the production of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the BALF and serum. In addition, NPS 2143 attenuated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and increased the activation of AMP-activated protein kinase (AMPK) in the lung. NPS 2143 also downregulated the activation of nuclear factor-kappa B (NF-κB) in the lung. In LPS-stimulated H292 airway epithelial cells, NPS 2143 attenuated the releases of IL-6 and MCP-1. Furthermore, NPS 2143 upregulated the activation of AMPK and downregulated the activation of NF-κB. These results suggest that NPS 2143 could be potential agent for the treatment of inflammatory diseases including ALI.

Elastase-Induced Parenchymal Disruption and Airway Hyper Responsiveness in Mouse Precision Cut Lung Slices: Toward an Ex vivo COPD Model

Background: COPD is a progressive lung disease characterized by emphysema and enhanced bronchoconstriction. Current treatments focused on bronchodilation can delay disease progression to some extent, but recovery or normalization of loss of lung function is impossible. Therefore, novel therapeutic targets are needed. The importance of the parenchyma in airway narrowing is increasingly recognized. In COPD, the parenchyma and extracellular matrix are altered, possibly affecting airway mechanics and enhancing bronchoconstriction. Our aim was to set up a comprehensive ex vivo Precision Cut Lung Slice (PCLS) model with a pathophysiology resembling that of COPD and integrate multiple readouts in order to study the relationship between parenchyma, airway functionality, and lung repair processes.

Methods: Lungs of C57Bl/6J mice were sliced and treated ex vivo with elastase (2.5 μg/ml) or H₂O₂ (200 μM) for 16 h. Following treatment, parenchymal structure, airway narrowing, and gene expression levels of alveolar Type I and II cell repair were assessed.

Results: Following elastase, but not H₂O₂ treatment, slices showed a significant increase in mean linear intercept (Lmi), reflective of emphysema. Only elastase-treated slices showed disorganization of elastin and collagen fibers. In addition, elastase treatment lowered both alveolar Type I and II marker expression, whereas H₂O₂ stimulation lowered alveolar Type I marker expression only. Furthermore, elastase-treated slices showed enhanced methacholine-induced airway narrowing as reflected by increased pEC50 (5.87 at basal vs. 6.50 after elastase treatment) and Emax values (47.96 vs. 67.30%), and impaired chloroquine-induced airway opening. The increase in pEC50 correlated with an increase in mean Lmi.

Conclusion: Using this model, we show that structural disruption of elastin fibers leads to impaired alveolar repair, disruption of the parenchymal compartment, and altered airway biomechanics, enhancing airway contraction. This finding may have implications for COPD, as the amount of elastin fiber and parenchymal tissue disruption is associated with disease severity. Therefore, we suggest that PCLS can be used to model certain aspects of COPD pathophysiology and that the parenchymal tissue damage observed in COPD contributes to lung function decline by disrupting airway biomechanics. Targeting the parenchymal compartment may therefore be a promising therapeutic target in the treatment of COPD.

Intermittent hypoxia during recovery from neonatal hyperoxic lung injury causes long-term impairment of alveolar development: A new rat model of BPD

Bronchopulmonary dysplasia (BPD) is a chronic lung injury characterized by impaired alveologenesis that may persist into adulthood. Rat models of BPD using varying degrees of hyperoxia to produce injury either cause early mortality or spontaneously recover following removal of the inciting stimulus, thus limiting clinical relevance. We sought to refine an established rat model induced by exposure to 60% O₂ from birth by following hyperoxia with intermittent hypoxia (IH). Rats exposed from birth to air or 60% O₂ until day 14 were recovered in air with or without IH (FI_O2 = 0.10 for 10 min every 6 h) until day 28 Animals exposed to 60% O₂ and recovered in air had no evidence of abnormal lung morphology on day 28 or at 10-12 wk. In contrast, 60% O₂-exposed animals recovered in IH had persistently increased mean chord length, more dysmorphic septal crests, and fewer peripheral arteries. Recovery in IH also increased pulmonary vascular resistance, Fulton index, and arterial wall thickness. IH-mediated abnormalities in lung structure (but not pulmonary hypertension) persisted when reexamined at 10-12 wk, accompanied by increased pulmonary vascular reactivity and decreased exercise tolerance. Increased mean chord length secondary to IH was prevented by treatment with a peroxynitrite decomposition catalyst [5,10,15,20-Tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin iron (III) chloride, 30 mg/kg/day, days 14-28], an effect accompanied by fewer inflammatory cells. We conclude that IH during recovery from hyperoxia-induced injury prevents recovery of alveologenesis and leads to changes in lung and pulmonary vascular function lasting into adulthood, thus more closely mimicking contemporary BPD.

The Role of Neutrophil Proteins on the Amyloid Beta-RAGE Axis

We previously showed an elevated expression of the neutrophil protein, cationic antimicrobial protein of 37kDa (CAP37), in brains of patients with Alzheimer’s disease (AD), suggesting that CAP37 could be involved in AD pathogenesis. The first step in determining how CAP37 might contribute to AD pathogenesis was to identify the receptor through which it induces cell responses. To identify a putative receptor, we performed GAMMA analysis to determine genes that positively correlated with CAP37 in terms of expression. Positive correlations with ligands for the receptor for advanced glycation end products (RAGE) were observed. Additionally, CAP37 expression positively correlated with two other neutrophil proteins, neutrophil elastase and cathepsin G. Enzyme-linked immunosorbent assays (ELISAs) demonstrated an interaction between CAP37, neutrophil elastase, and cathepsin G with RAGE. Amyloid beta 1–42 (Aβ_1–42), a known RAGE ligand, accumulates in AD brains and interacts with RAGE, contributing to Aβ_1–42 neurotoxicity. We questioned whether the binding of CAP37, neutrophil elastase and/or cathepsin G to RAGE could interfere with Aβ_1–42 binding to RAGE. Using ELISAs, we determined that CAP37 and neutrophil elastase inhibited binding of Aβ_1–42 to RAGE, and this effect was reversed by protease inhibitors in the case of neutrophil elastase. Since neutrophil elastase and cathepsin G have enzymatic activity, mass spectrometry was performed to determine the proteolytic activity of all three neutrophil proteins on Aβ_1–42. All three neutrophil proteins bound to Aβ_1–42 with different affinities and cleaved Aβ_1–42 with different kinetics and substrate specificities. We posit that these neutrophil proteins could modulate neurotoxicity in AD by cleaving Aβ_1–42 and influencing the Aβ1–42 –RAGE interaction. Further studies will be required to determine the biological significance of these effects and their relevance in neurodegenerative diseases such as AD. Our findings identify a novel area of study that underscores the importance of neutrophils and neutrophil proteins in neuroinflammatory diseases such as AD.

The Extracellular Matrix in Bronchopulmonary Dysplasia: Target and Source

Bronchopulmonary dysplasia (BPD) is a common complication of preterm birth that contributes significantly to morbidity and mortality in neonatal intensive care units. BPD results from life-saving interventions, such as mechanical ventilation and oxygen supplementation used to manage preterm infants with acute respiratory failure, which may be complicated by pulmonary infection. The pathogenic pathways driving BPD are not well-delineated but include disturbances to the coordinated action of gene expression, cell-cell communication, physical forces, and cell interactions with the extracellular matrix (ECM), which together guide normal lung development. Efforts to further delineate these pathways have been assisted by the use of animal models of BPD, which rely on infection, injurious mechanical ventilation, or oxygen supplementation, where histopathological features of BPD can be mimicked. Notable among these are perturbations to ECM structures, namely, the organization of the elastin and collagen networks in the developing lung. Dysregulated collagen deposition and disturbed elastin fiber organization are pathological hallmarks of clinical and experimental BPD. Strides have been made in understanding the disturbances to ECM production in the developing lung, but much still remains to be discovered about how ECM maturation and turnover are dysregulated in aberrantly developing lungs. This review aims to inform the reader about the state-of-the-art concerning the ECM in BPD, to highlight the gaps in our knowledge and current controversies, and to suggest directions for future work in this exciting and complex area of lung development (patho)biology.