Amelioration of Cigarette Smoke-Induced Mucus Hypersecretion and Viscosity by Dendrobium officinale Polysaccharides In Vitro and In Vivo

Mucus Structure, Viscoelastic Properties, and Composition in Chronic Respiratory Diseases

The respiratory mucus, a viscoelastic gel, effectuates a primary line of the airway defense when operated by the mucociliary clearance. In chronic respiratory diseases (CRDs), such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), the mucus is overproduced and its solid content augments, changing its structure and viscoelastic properties and determining a derangement of essential defense mechanisms against opportunistic microbial (virus and bacteria) pathogens. This ensues in damaging of the airways, leading to a vicious cycle of obstruction and infection responsible for the harsh clinical evolution of these CRDs. Here, we review the essential features of normal and pathological mucus (i.e., sputum in CF, COPD, and asthma), i.e., mucin content, structure (mesh size), micro/macro-rheology, pH, and osmotic pressure, ending with the awareness that sputum biomarkers (mucins, inflammatory proteins and peptides, and metabolites) might serve to indicate acute exacerbation and response to therapies. There are some indications that old and novel treatments may change the structure, viscoelastic properties, and biomarker content of sputum; however, a wealth of work is still needed to embrace these measures as correlates of disease severity in association with (or even as substitutes of) pulmonary functional tests.

Caveolin-1-derived peptide attenuates cigarette smoke-induced airway and alveolar epithelial injury

Chronic obstructive pulmonary disease (COPD) is a debilitating lung disease with no effective treatment that can reduce mortality or slow the disease progression. COPD is the third leading cause of global death and is characterized by airflow limitations due to chronic bronchitis and alveolar damage/emphysema. Chronic cigarette smoke (CS) exposure damages airway and alveolar epithelium and remains a major risk factor for the pathogenesis of COPD. We found that the expression of caveolin-1, a tumor suppressor protein; p53; and plasminogen activator inhibitor-1 (PAI-1), one of the downstream targets of p53, was markedly increased in airway epithelial cells (AECs) as well as in type II alveolar epithelial (AT2) cells from the lungs of patients with COPD or wild-type mice with CS-induced lung injury (CS-LI). Moreover, p53- and PAI-1-deficient mice resisted CS-LI. Furthermore, treatment of AECs, AT2 cells, or lung tissue slices from patients with COPD or mice with CS-LI with a seven amino acid caveolin-1 scaffolding domain peptide (CSP7) reduced mucus hypersecretion in AECs and improved AT2 cell viability. Notably, induction of PAI-1 expression via increased caveolin-1 and p53 contributed to mucous cell metaplasia and mucus hypersecretion in AECs, and reduced AT2 viability, due to increased senescence and apoptosis, which was abrogated by CSP7. In addition, treatment of wild-type mice having CS-LI with CSP7 by intraperitoneal injection or nebulization via airways attenuated mucus hypersecretion, alveolar injury, and significantly improved lung function. This study validates the potential therapeutic role of CSP7 for treating CS-LI and COPD. NEW & NOTEWORTHY Chronic cigarette smoke (CS) exposure remains a major risk factor for the pathogenesis of COPD, a debilitating disease with no effective treatment. Increased caveolin-1 mediated induction of p53 and downstream plasminogen activator inhibitor-1 (PAI-1) expression contributes to CS-induced airway mucus hypersecretion and alveolar wall damage. This is reversed by caveolin-1 scaffolding domain peptide (CSP7) in preclinical models, suggesting the therapeutic potential of CSP7 for treating CS-induced lung injury (CS-LI) and COPD.

Effects of Z-VaD-Ala-Asp-Fluoromethyl Ketone (Z-VAD-FMK) and Acetyl-Asp-Glu-Val-Asp-Aldehyde(Ac-DEVD-CHO) on Inflammation and Mucus Secretion in Mice Exposed to Cigarette Smoke

Background and Objectives

Smoking can lead to airway inflammation and mucus secretion through the nucleotide-binding domain-like receptor protein 3/caspase-1 pathway. In this study, z-VaD-Ala-Asp-fluoromethyl ketone(Z-VAD), a pan-caspase inhibitor, and acetyl-Asp-Glu-Val-Asp-aldehyde(Ac-DEVD), a caspase-3 inhibitor, were used to investigate the effect of caspase inhibitors on the expression of interleukin(IL)-1β and IL-8, airway inflammation, and mucus secretion in mice exposed to cigarette smoke(CS).

Methods

Thirty-two C57BL/6J male mice were divided into a control group, Smoke group, Z-VAD group, and Ac-DEVD group. Except for the control group, the animals were all exposed to CS for three months. After the experiment, lung function was measured and hematoxylin and eosin staining and periodic acid-Schiff staining were performed. The levels of IL-1β, IL-8, and mucin 5ac(Muc5ac) in serum and bronchoalveolar lavage fluid(BALF) were determined by enzyme-linked immunosorbent assay.

Results

Compared with the control group, the lung function of mice exposed to smoke was poorer, with a large number of inflammatory cells infiltrating around the airway, collapse of alveoli, expansion and fusion of distal alveoli, and formation of emphysema. The Z-VAD group was relieved compared with the smoke group. Airway inflammation was also reduced in the Ac-DEVD group compared with the Smoke group, but the degree of emphysema was not significantly improved. Although Z-VAD relieved airway inflammation and emphysema, Ac-DEVD only relieved inflammation. Z-VAD and Ac-DEVD decreased serum IL-1β and IL-8 levels. In BALF, IL-1β was decreased in Z-VAD group and IL-8 was highest in Smoke +Ac-DEVD group compared with control group and Ac-DEVD group. There was no significant difference in the expression of Muc5ac in serum. However, in BALF, levels of Muc5ac were higher in the smoking group and the lowest in the Ac-DEVD group.

Conclusion

Mice exposed to smoke had decreased lung function and significant cilia lodging, epithelial cell shedding, and inflammatory cell infiltration, with significant emphysema formation. The pan-caspase inhibitor, Z-VAD, improved airway inflammation and emphysema lesions in the mice exposed to smoke and reduced IL-1β and IL-8 levels in serum. The caspase-3 inhibitor, Ac-DEVD, reduced airway inflammation, serum IL-1β and IL-8 levels, and Muc5ac levels in BALF, but it did not improve emphysema.

Interactions of Inhaled Liposome with Macrophages and Neutrophils Determine Particle Biofate and Anti-Inflammatory Effect in Acute Lung Inflammation

Since most current studies have focused on exploring how phagocyte internalization of drug-loaded nanovesicles by macrophages would affect the function and therapeutic effects of infiltrated neutrophils or monocytes, research has evaluated the specificity of the inhaled nanovesicles for targeting various phagocytes subpopulations. In this study, liposomes with various charges (including neutral (L1), anionic (L2), and cationic at inflammatory sites (L3)) were constructed to investigate how particle charge determined their interactions with key phagocytes (including macrophages and neutrophils) in acute lung injury (ALI) models and to establish correlations with their biofate and overall anti-inflammatory effect. Our results clearly indicated that neutrophils were capable of rapidly sequestering L3 with a 3.2-fold increase in the cellular liposome distribution, compared to that in AMs, while 70.5% of L2 were preferentially uptaken by alveolar macrophages (AMs). Furthermore, both AMs and the infiltrated neutrophils performed as the potential vesicles for the inhaled liposomes to prolong their lung retention in ALI models, whereas AMs function as sweepers to recognize and process liposomes in the healthy lung. Finally, inhaled roflumilast-loaded macrophage or neutrophil preferential liposomes (L2 or L3) exhibited optimal anti-inflammatory effect because of the decreased AMs phagocytic capacity or the prolonged circulation times of neutrophils. Such findings will be beneficial in exploiting a potential pathway to specifically manipulate lung phagocyte functions in lung inflammatory diseases where these cells play crucial roles.

Bioactivities and Mechanism of Actions of Dendrobium officinale: A Comprehensive Review

Dendrobium officinale has a long history of being consumed as a functional food and medicinal herb for preventing and managing diseases. The phytochemical studies revealed that Dendrobium officinale contained abundant bioactive compounds, such as bibenzyls, polysaccharides, flavonoids, and alkaloids. The experimental studies showed that Dendrobium officinale and its bioactive compounds exerted multiple biological properties like antioxidant, anti-inflammatory, and immune-regulatory activities and showed various health benefits like anticancer, antidiabetes, cardiovascular protective, gastrointestinal modulatory, hepatoprotective, lung protective, and neuroprotective effects. In this review, we summarize the phytochemical studies, bioactivities, and the mechanism of actions of Dendrobium officinale, and the safety and current challenges are also discussed, which might provide new perspectives for its development of drug and functional food as well as clinical applications.

Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molecular mechanisms and the cellular functions altered by cigarette smoke extract (CSE) exposure, and to test the efficacy of molecules with antioxidant properties. This review offers a comprehensive synthesis of human in-vitro and ex-vivo studies published from 2011 to 2021 describing the molecular and cellular mechanisms evoked by CSE exposure in bronchial epithelial cells, the most used experimental models and the mechanisms of action of cellular antioxidants systems as well as natural and synthetic antioxidant compounds.

Therapeutic potential and mechanism of Dendrobium officinale polysaccharides on cigarette smoke-induced airway inflammation in rat

Chronic obstructive pulmonary disease (COPD) is among the leading causes of death worldwide, and is characterized by persistent respiratory symptoms and airflow limitation due to chronic airway inflammation. Cigarette smoking is a major risk factor for COPD. This study aims to determine the therapeutic effects of polysaccharides extracted from Dendrobium officinale (DOPs), a valuable traditional Chinese Medicinal herb, on cigarette smoke (CS)-induced airway inflammation in a rat passive smoking model. Male Sprague-Dawley rats were exposed to CS or sham air (SA) as control for a 56-day period. On Day 29, rats were subdivided and given water, DOPs or N-acetylcysteine (NAC) via oral gavage on a daily basis for the remaining duration. DOPs reduced CS-induced oxidative stress as evidenced by reducing malondialdehyde (MDA) levels in the lung. DOPs also exerted potent anti-inflammatory properties as evidenced by a reduction in the number of lymphocytes and monocytes in serum, significantly attenuating infiltration of inflammatory cells in lung tissue, as well as pro-inflammatory mediators in serum, bronchoalveolar lavage (BAL) and lung. Additionally, DOPs inhibited the CS-induced activation of ERK, p38 MAPK and NF-κB signaling pathways. These findings suggest that DOPs may have potentially beneficial effects in limiting smoking-related lung oxidative stress, and inflammation mediated via the inhibition of MAPK and NF-κB signaling pathways in smokers, without or with COPD.

Traditional Uses, Phytochemistry, Pharmacology, and Quality Control of Dendrobium officinale Kimura et. Migo

Dendrobium officinale, a well-known plant used as a medicinal and food homologous product, has been reported to contain various bioactive components, such as polysaccharides, bibenzyls, phenanthrenes, and flavonoids. It is also widely used as a traditional medicine to strengthen “Yin”, nourish heart, tonify five viscera, remove arthralgia, relieve fatigue, thicken stomach, lighten body, and prolong life span. These traditional applications are in consistent with modern pharmacological studies, which have demonstrated that D. officinale exhibits various biological functions, such as cardioprotective, anti-tumor, gastrointestinal protective, anti-diabetes, immunomodulatory, anti-aging, and anti-osteoporosis effects. In this review, we summarize the research progress of D. officinale from November 2016 to May 2021 and aim to better understand the botany, traditional use, phytochemistry, and pharmacology of D. officinale, as well as its quality control and safety. This work presents the development status of D. officinale, analyzes gaps in the current research on D. officinale, and raises the corresponding solutions to provide references and potential directions for further studies of D. officinale.