Characterization of a novel model incorporating airway epithelial damage and related fibrosis to the pathogenesis of asthma

Anti-inflammatory and anti-allergic effects of Cheonwangbosim-dan water extract: An in vitro and in vivo study

Ethnopharmacological relevance

Cheonwangbosim-dan is a traditional herbal prescription that is widely used to improve or treat physical and mental illnesses in East Asian countries.Aim of the study: The aim of the present study was to investigate the preventive and protective effects of a Cheonwangbosim-dan water extract (CBDW) against allergic inflammation using in vitro and in vivo models.

Materials and methods

BEAS-2B and MC/9 cells were treated with various concentrations of CBDW and stimulated with different inducers of inflammatory mediators. The production of various inflammatory mediators was subsequently evaluated. BALB/c mice were sensitized and challenged by repeated application of ovalbumin (OVA). CBDW was administered by oral gavage once daily for 10 consecutive days. We assessed the number of inflammatory cells and production of Th2 cytokines in bronchoalveolar lavage fluid (BALF), the plasma levels of total and OVA-specific immunoglobulin E (IgE), and histological changes in lung tissue.

Results

Our findings showed that CBDW significantly decreased the levels of various inflammatory mediators (eotaxin-1, eotaxin-3, RANTES, LTC₄, TNF-α, MMP-9, 5-LO, ICAM-1, and VCAM-1) in vitro, significantly reduced the accumulation of total inflammatory cells, the production of Th2 cytokines (IL-5 and IL-13), the levels of IgE (total and OVA-specific) in vivo, and remarkably inhibited histological changes (infiltration of inflammatory cells and goblet cell hyperplasia) in vivo.

Conclusions

These results suggest that CBDW possesses anti-inflammatory and anti-allergic properties by lowering allergic inflammation.

Exosomal let-7i-5p from three-dimensional cultured human umbilical cord mesenchymal stem cells inhibits fibroblast activation in silicosis through targeting TGFBR1

Silicosis of pulmonary fibrosis (PF) is related to long-term excessive inhalation of silica. The activation of fibroblasts into myofibroblasts is the main terminal effect leading to lung fibrosis, which is of great significance to the study of the occurrence and development of silicosis fibrosis and its prevention and treatment. Exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-Exos) are considered to be a potential therapy of silica-induced PF, however, their exact mechanism remains unknown. Therefore, this study aims to explore whether hucMSC-Exos affect the activation of fibroblasts to alleviate PF. In this study, a three-dimensional (3D) method was applied to culture hucMSCs and MRC-5 cells (human embryonic lung fibroblasts), and exosomes were isolated from serum-free media, identified by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and Western blotting analysis. Then, the study used an animal model of silica-induced PF to observe the effects of hucMSC-Exos and MRC-5-Exos on activation of fibroblasts. In addition, the activation of fibroblasts was analyzed by Western blotting analysis, wound healing, and migration assay with the treatment of hucMSC-Exos and MRC-5-Exos in NIH-3T3 cells (mouse embryonic fibroblasts). Furthermore, differential expression of microRNAs (DE miRNAs) was measured between hucMSCs-Exos and MRC-5-Exos by high throughput sequence. HucMSC-Exos inhibited the activation of fibroblasts in mice and NIH-3T3 cells. Let-7i-5p was significantly up-regulated in hucMSCs-Exos compared to MRC-5-Exos, which was related to silica-induced PF. Let-7i-5p of hucMSCs-Exos was responsible for the activation of fibroblasts by targeting TGFBR1. Meanwhile, Smad3 was also an important role in the activation of fibroblasts. The study demonstrates that hucMSCs-Exos act as a mediator that transfers let-7i-5p to inhibit the activation of fibroblasts, which alleviates PF through the TGFBR1/Smad3 signaling pathway. The mechanism has potential value for the treatment of silica-induced PF.

Anisakis pegreffii Extract Induces Airway Inflammation with Airway Remodeling in a Murine Model System

Exposure of the respiratory system to the Anisakis pegreffii L3 crude extract (AE) induces airway inflammation; however, the mechanism underlying this inflammatory response remains unknown. AE contains allergens that promote allergic inflammation; exposure to AE may potentially lead to asthma. In this study, we aimed to establish a murine model to assess the effects of AE on characteristic features of chronic asthma, including airway hypersensitivity (AHR), airway inflammation, and airway remodeling. Mice were sensitized for five consecutive days each week for 4 weeks. AHR, lung inflammation, and airway remodeling were evaluated 24 h after the last exposure. Lung inflammation and airway remodeling were assessed from the bronchoalveolar lavage fluid (BALF). To confirm the immune response in the lungs, changes in gene expression in the lung tissue were assessed with reverse transcription-quantitative PCR. The levels of IgE, IgG1, and IgG2a in blood and cytokine levels in the BALF, splenocyte, and lung lymph node (LLN) culture supernatant were measured with ELISA. An increase in AHR was prominently observed in AE-exposed mice. Epithelial proliferation and infiltration of inflammatory cells were observed in the BALF and lung tissue sections. Collagen deposition was detected in lung tissues. AE exposure increased IL-4, IL-5, and IL-13 expression in the lung, as well as the levels of antibodies specific to AE. IL-4, IL-5, and IL-13 were upregulated only in LLN. These findings indicate that an increase in IL-4+ CD4+ T cells in the LLN and splenocyte resulted in increased Th2 response to AE exposure. Exposure of the respiratory system to AE resulted in an increased allergen-induced Th2 inflammatory response and AHR through accumulation of inflammatory and IL-4+ CD4+ T cells and collagen deposition. It was confirmed that A. pegreffii plays an essential role in causing asthma in mouse models and has the potential to cause similar effects in humans.

Investigation of molecular mechanisms of experimental compounds in murine models of chronic allergic airways disease using synchrotron Fourier-transform infrared microspectroscopy

The ovalbumin-induced (OVA) chronic allergic airways murine model is a well-established model for investigating pre-clinical therapies for chronic allergic airways diseases, such as asthma. Here, we examined the effects of several experimental compounds with potential anti-asthmatic effects including resveratrol (RV), relaxin (RLN), l-sulforaphane (LSF), valproic acid (VPA), and trichostatin A (TSA) using both a prevention and reversal model of chronic allergic airways disease. We undertook a novel analytical approach using focal plane array (FPA) and synchrotron Fourier-transform infrared (S-FTIR) microspectroscopic techniques to provide new insights into the mechanisms of action of these experimental compounds. Apart from the typical biological effects, S-FTIR microspectroscopy was able to detect changes in nucleic acids and protein acetylation. Further, we validated the reduction in collagen deposition induced by each experimental compound evaluated. Although this has previously been observed with conventional histological methods, the S-FTIR technique has the advantage of allowing identification of the type of collagen present. More generally, our findings highlight the potential utility of S-FTIR and FPA-FTIR imaging techniques in enabling a better mechanistic understanding of novel asthma therapeutics.

Plasma CC16 mediates the associations between urinary metals and fractional exhaled nitric oxide: A cross-sectional study

Exposure to environmental metals has been reported to be associated with airway inflammation. Fractional exhaled nitric oxide (FeNO) is an important inflammatory biomarker of the airway. However, the associations between metal exposures and FeNO change and the underlying mechanisms remain unclear. To investigate the associations between urinary metals and FeNO, and the potential role of Club cell secretory protein (CC16), a lung epithelial biomarker, in these associations. We conducted a cross-sectional study from the Wuhan-Zhuhai cohort and measured eight urinary metals, plasma CC16 and FeNO among 3067 subjects by using inductively coupled plasma-mass spectrometry, enzyme-linked immunosorbent assay kit and Nano Coulomb Nitric Oxide Analyzer, respectively. Mixed linear models were used to quantify dose-relationships between urinary metals and FeNO, as well as urinary metals and plasma CC16. The potential role of plasma CC16 in the associations between urinary metals and FeNO was estimated using mediationanalyses. After adjusting for covariates, one percent increase in urinary vanadium, nickel or antimony was associated with a respective 6.60% (95% CI: 3.52%, 9.68%), 2.18% (0.45%, 3.91%), 4.87% (1.47%, 8.27%) increase in FeNO level. The adverse associations were much stronger among participants with low concentration of plasma CC16 than those with high CC16 level. Moreover, plasma CC16 decreased monotonically with increasing quartiles of urinary vanadium, nickel or antimony. Mediation analyses found that CC16 mediated the associations between urinary metals and FeNO by 5.64%, 39.06% and 25.18% for vanadium, nickel and antimony respectively. CC16 plays an important role in airway inflammation. General population with lower plasma CC16 concentration is more likely to suffer from airway inflammation when exposed to high levels of vanadium, nickel or antimony.

Dual role of RACK1 in airway epithelial mesenchymal transition and apoptosis

Airway epithelial apoptosis and epithelial mesenchymal transition (EMT) are two crucial components of asthma pathogenesis, concomitantly mediated by TGF‐β1. RACK1 is the downstream target gene of TGF‐β1 shown to enhancement in asthma mice in our previous study. Balb/c mice were sensitized twice and challenged with OVA every day for 7 days. Transformed human bronchial epithelial cells, BEAS‐2B cells were cultured and exposed to recombinant soluble human TGF‐β1 to induced apoptosis (30 ng/mL, 72 hours) and EMT (10 ng/mL, 48 hours) in vitro, respectively. siRNA and pharmacological inhibitors were used to evaluate the regulation of RACK1 protein in apoptosis and EMT. Western blotting analysis and immunostaining were used to detect the protein expressions in vivo and in vitro. Our data showed that RACK1 protein levels were significantly increased in OVA‐challenged mice, as well as TGF‐β1‐induced apoptosis and EMT of BEAS‐2B cells. Knockdown of RACK1 (siRACK1) significantly inhibited apoptosis and decreased TGF‐β1 up‐regulated EMT related protein levels (N‐cadherin and Snail) in vitro via suppression of JNK and Smad3 activation. Moreover, siSmad3 or siJNK impaired TGF‐β1‐induced N‐cadherin and Snail up‐regulation in vitro. Importantly, JNK gene silencing (siERK) also impaired the regulatory effect of TGF‐β1 on Smad3 activation. Our present data demonstrate that RACK1 is a concomitant regulator of TGF‐β1 induces airway apoptosis and EMT via JNK/Smad/Snail signalling axis. Our findings may provide a new insight into understanding the regulation mechanism of RACK1 in asthma pathogenesis.

Serelaxin enhances the therapeutic effects of human amnion epithelial cell-derived exosomes in experimental models of lung disease

BACKGROUND AND PURPOSE

There is growing interest in stem cell-derived exosomes for their therapeutic and regenerative benefits given their manufacturing and regulatory advantages over cell-based therapies. As existing fibrosis impedes the viability and efficacy of stem cell/exosome-based strategies for treating chronic diseases, here we tested the effects of the anti-fibrotic drug, serelaxin, on the therapeutic efficacy of human amnion epithelial cell (AEC)-derived exosomes in experimental lung disease.

EXPERIMENTAL APPROACH

Female Balb/c mice were subjected to either the 9.5-week model of ovalbumin and naphthalene (OVA/NA)-induced chronic allergic airway disease (AAD) or 3-week model of bleomycin (BLM)-induced pulmonary fibrosis; then administered increasing concentrations of AEC-exosomes (5 μg or 25μg), with or without serelaxin (0.5mg/kg/day) for 7-days. 1x10⁶ AECs co-administered with serelaxin over the corresponding time-period were included for comparison in both models, as was pirfenidone-treatment of the BLM model. Control groups received saline/corn oil or saline, respectively.

KEY RESULTS

Both experimental models presented with significant tissue inflammation, remodelling, fibrosis and airway/lung dysfunction at the time-points studied. While AEC-exosome (5 μg or 25μg)-administration alone demonstrated some benefits in each model, serelaxin was required for AEC-exosomes (25μg) to rapidly normalise chronic AAD-induced airway fibrosis and airway reactivity, and BLM-induced lung inflammation, epithelial damage and subepithelial/basement membrane fibrosis. Combining serelaxin with AEC-exosomes (25μg) also demonstrated broader protection compared to co-administration of serelaxin with 1x10⁶ AECs or pirfenidone.

CONCLUSIONS AND IMPLICATIONS

Serelaxin enhanced the therapeutic efficacy of AEC-exosomes in treating basement membrane-induced fibrosis and related airway dysfunction.

The Cell Research Trends of Asthma: A Stem Frequency Analysis of the Literature

Objective

This study summarized asthma literature indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) and explored the history and present trends of asthma cell research by stem frequency ranking to forecast the prospect of future work.

Methods

Literature was obtained from MEDLINE for the past 30 years and divided into three groups by decade as the retrieval time. The frequency of stemmed words in each group was calculated using Python with Apache Spark and the Natural Language Tool Kit for ranking. The unique stems or shared stems of 3 decades were summarized.

Results

A total of 1331, 4393, and 7215 records were retrieved from 3 decades chronologically, and the stem ranking of the top 50 were listed by frequency. The number of stems shared with 3 decades was 26 and with the first and last 2 decades was 5 and 13.

Conclusions

The number of cell research studies of asthma has increased rapidly, and scholars have paid more attentions on experimental research, especially on mechanistic research. Eosinophils, mast cells, and T cells are the hot spots of immunocyte research, while epithelia and smooth muscle cells are the hot spots of structural cell research. The research trend is closely linked with the development of experimental technology, including animal models. Early studies featured basic research, but immunity research has dominated in recent decades. The distinct definition of asthma phenotypes associated with genetic characteristics, immunity research, and the introduction of new cells will be the hot spots in future work.

Irritant-induced asthma to hypochlorite in mice due to impairment of the airway barrier

Inhalation of commonly present irritants, such as chlorine and chlorine derivatives, can cause adverse respiratory effects, including irritant-induced asthma (IIA). We hypothesize that due to airway barrier impairment, exposure to hypochlorite (ClO^-) can result in airway hypersensitivity. C57Bl/6 mice received an intra-peritoneal (i.p.) injection of the airway damaging agent naphthalene (NA, 200 mg/kg body weight) or vehicle (mineral oil, MO). In vivo micro-computed tomography (CT) images of the lungs were acquired before and at regular time points after the i.p.

TREATMENT

After a recovery period of 14 days an intranasal (i.n.) challenge with 0.003% active chlorine (in ClO^-) or vehicle (distilled water, H₂O) was given, followed by assessment of the breathing frequency. One day later, pulmonary function, along with pulmonary inflammation was determined. Lung permeability was assessed by means of total broncho-alveolar lavage (BAL) protein content and plasma surfactant protein (SP)-D levels. In vivo micro-CT imaging revealed enlargement of the lungs and airways early after NA treatment, with a return to normal at day 14. When challenged i.n. with ClO^-, NA-pretreated mice immediately responded with a sensory irritant response. Twenty-four hours later, NA/ClO^- mice showed airway hyperreactivity (AHR), accompanied by a neutrophilic and eosinophilic inflammation. NA administration followed by ClO^- induced airway barrier impairment, as shown by increased BAL protein and plasma SP-D concentrations; histology revealed epithelial denudation. These data prove that NA-induced lung impairment renders the lungs of mice more sensitive to an airway challenge with ClO^-, confirming the hypothesis that incomplete barrier repair, followed by irritant exposure results in airway hypersensitivity.

Lung responses in murine models of experimental asthma: Value of house dust mite over ovalbumin sensitization

Ovalbumin (OVA) sensitization has limitations in modelling asthma. Thus, we examined the value of allergic sensitization using a purified natural allergen, house dust mite (HDM), over the sensitization performed with OVA. Mice were sham-treated, or sensitized with OVA- or HDM with identical chronology. Airway resistance, tissue damping and elastance were assessed under control conditions and after challenging the animals with methacholine (MCh) and the specific allergen. Inflammatory profile of the bronchoalveolar lavage fluid was characterized and lung histology was performed. While no difference in the lung responsiveness to the specific allergen was noted, hyperresponsiveness to MCh was observed only in the HDM-sensitized animals in the lung peripheral parameters. Lung inflammation differed between the models, but excessive bronchial smooth muscle remodelling occurred only with OVA. In conclusion, we demonstrate that a purified natural allergen offers a more relevant murine model of human allergic asthma by expressing the key features of this chronic inflammatory disease both in the lung function and structure.

Airway Remodeling and Hyperreactivity in a Model of Bronchopulmonary Dysplasia and Their Modulation by IL-1 Receptor Antagonist

Bronchopulmonary dysplasia (BPD) is a chronic disease of extreme prematurity that has serious long-term consequences including increased asthma risk. We earlier identified IL-1 receptor antagonist (IL-1Ra) as a potent inhibitor of murine BPD induced by combining perinatal inflammation (intraperitoneal LPS to pregnant dams) and exposure of pups to hyperoxia (fraction of inspired oxygen = 0.65). In this study, we determined whether airway remodeling and hyperresponsiveness similar to asthma are evident in this model, and whether IL-1Ra is protective. During 28-day exposure to air or hyperoxia, pups received vehicle or 10 mg/kg IL-1Ra by daily subcutaneous injection. Lungs were then prepared for histology and morphometry of alveoli and airways, or for real-time PCR, or inflated with agarose to prepare precision-cut lung slices to visualize ex vivo intrapulmonary airway contraction and relaxation by phase-contrast microscopy. In pups reared under normoxic conditions, IL-1Ra treatment did not affect alveolar or airway structure or airway responses. Pups reared in hyperoxia developed a severe BPD-like lung disease, with fewer, larger alveoli, increased subepithelial collagen, and increased expression of α-smooth muscle actin and cyclin D1. After hyperoxia, methacholine elicited contraction with similar potency but with an increased maximum reduction in lumen area (air, 44%; hyperoxia, 89%), whereas dilator responses to salbutamol were maintained. IL-1Ra treatment prevented hyperoxia-induced alveolar disruption and airway fibrosis but, surprisingly, not the increase in methacholine-induced airway contraction. The current study is the first to demonstrate ex vivo airway hyperreactivity caused by systemic maternal inflammation and postnatal hyperoxia, and it reveals further preclinical mechanistic insights into IL-1Ra as a treatment targeting key pathophysiological features of BPD.

Aqueous Extract of Gumiganghwal-tang, a Traditional Herbal Medicine, Reduces Pulmonary Fibrosis by Transforming Growth Factor-β1/Smad Signaling Pathway in Murine Model of Chronic Asthma

Gumiganghwal-tang is a traditional herbal prescription that is used widely for the treatment of the common cold and inflammatory diseases in Korea and other Asian countries. In this study, we investigated the protective effects of a Gumiganghwal-tang aqueous extract (GGTA) against airway inflammation and pulmonary fibrosis using a mouse model of chronic asthma. Chronic asthma was modeled in BALB/c mice via sensitization/challenge with an intraperitoneal injection of 1% ovalbumin (OVA) and inhalation of nebulized 1% OVA for 4 weeks. GGTA (100 mg/kg or 200 mg/kg) was also administered by oral gavage once a day for 4 weeks. We investigated the number of inflammatory cells, production of T-helper type 2 (Th2) cytokines, chemokine and the total transforming growth factor-β1 (TGF-β1) in bronchoalveolar lavage fluid (BALF); the levels of immunoglobulin E (IgE) in the plasma; the infiltration of inflammatory cells in lung tissue; and the expression of TGF-β1, Smad-3, and collagen in lung tissue. Our results revealed that GGTA lowered the recruitment of inflammatory cells (particularly, lymphocyte); and decreased the production of Th2 cytokines, chemokine and total TGF-β1; and attenuated the levels of total and OVA-specific IgE; and decreased the infiltration of inflammatory cells. Moreover, GGTA significantly reduced the expression of TGF-β1 and Smad-3, and lowered collagen deposition. These results indicate that GGTA reduces airway inflammation and pulmonary fibrosis by regulating Th2 cytokines production and the TGF-β1/Smad-3 pathway, thus providing a potential treatment for chronic asthma.

Combining an epithelial repair factor and anti-fibrotic with a corticosteroid offers optimal treatment for allergic airways disease

BACKGROUND AND PURPOSE

We evaluated the extent to which individual versus combination treatments that specifically target airway epithelial damage [trefoil factor-2 (TFF2)], airway fibrosis [serelaxin (RLX)] or airway inflammation [dexamethasone (DEX)] reversed the pathogenesis of chronic allergic airways disease (AAD).

EXPERIMENTAL APPROACH

Following induction of ovalbumin (OVA)-induced chronic AAD in 6–8 week female Balb/c mice, animals were i.p. administered naphthalene (NA) on day 64 to induce epithelial damage, then received daily intranasal administration of RLX (0.8 mg·mL(−1)), TFF2 (0.5 mg·mL(−1)), DEX (0.5 mg·mL(−1)), RLX + TFF2 or RLX + TFF2 + DEX from days 67–74. On day 75, lung function was assessed by invasive plethysmography, before lung tissue was isolated for analyses of various measures. The control group was treated with saline + corn oil (vehicle for NA).

KEY RESULTS

OVA + NA-injured mice demonstrated significantly increased airway inflammation, airway remodelling (AWR) (epithelial damage/thickness; subepithelial myofibroblast differentiation, extracellular matrix accumulation and fibronectin deposition; total lung collagen concentration), and significantly reduced airway dynamic compliance (cDyn). RLX + TFF2 markedly reversed several measures of OVA + NA-induced AWR and normalized the reduction in cDyn. The combined effects of RLX + TFF2 + DEX significantly reversed peribronchial inflammation score, airway epithelial damage, subepithelial extracellular matrix accumulation/fibronectin deposition and total lung collagen concentration (by 50–90%) and also normalized the reduction of cDyn.

CONCLUSIONS AND IMPLICATIONS

Combining an epithelial repair factor and anti-fibrotic provides an effective means of treating the AWR and dysfunction associated with AAD/asthma and may act as an effective adjunct therapy to anti-inflammatory corticosteroids