Neutrophils and emerging targets for treatment in chronic obstructive pulmonary disease

Astragalin Inhibits Allergic Inflammation and Airway Thickening in Ovalbumin-Challenged Mice

Lung inflammation and oxidative stress are the major contributors to the development of obstructive pulmonary diseases. Macrophages are involved in pulmonary inflammation and alveolar damage in emphysema. Astragalin is an anti-inflammatory flavonoid present in persimmon leaves and green tea seeds. This study elucidated that astragalin inhibited inflammatory cell infiltration induced by 20 μM H₂O₂ and blocked airway thickening and alveolar emphysema induced by 20 μg of ovalbumin (OVA) in mice. OVA induced mouse pulmonary MCP-1, and H₂O₂ enhanced the expression of MCP-1/ICAM-1/αv integrin in bronchial airway epithelial BEAS-2B cells. Such induction was inhibited by supplying 10-20 mg/kg of astragalin to OVA-challenged mice and 1-20 μM astragalin to oxidant-stimulated cells. Oral administration of 20 mg/kg of astragalin reduced the induction of F4/80/CD68/CD11b in airways of mice challenged with OVA. Additionally, emphysema tissue damage was observed in OVA-exposed alveoli. Mast cell recruitment in the airway subepithelium was blocked by supplementing astragalin to OVA-challenged mice. Orally treating 20 mg/kg of astragalin reduced α-SMA induction in inflammation-occurring airways and appeared to reverse airway thickening and constriction induced by an OVA episode. These results revealed that astragalin may improve airway thickening and alveolar destruction with blockade of allergic inflammation in airways. Therefore, astragalin may be a therapeutic agent antagonizing asthma and obstructive pulmonary diseases.

Lung inflammation caused by inhaled toxicants: a review

Exposure of the lungs to airborne toxicants from different sources in the environment may lead to acute and chronic pulmonary or even systemic inflammation. Cigarette smoke is the leading cause of chronic obstructive pulmonary disease, although wood smoke in urban areas of underdeveloped countries is now recognized as a leading cause of respiratory disease. Mycotoxins from fungal spores pose an occupational risk for respiratory illness and also present a health hazard to those living in damp buildings. Microscopic airborne particulates of asbestos and silica (from building materials) and those of heavy metals (from paint) are additional sources of indoor air pollution that contributes to respiratory illness and is known to cause respiratory illness in experimental animals. Ricin in aerosolized form is a potential bioweapon that is extremely toxic yet relatively easy to produce. Although the aforementioned agents belong to different classes of toxic chemicals, their pathogenicity is similar. They induce the recruitment and activation of macrophages, activation of mitogen-activated protein kinases, inhibition of protein synthesis, and production of interleukin-1 beta. Targeting either macrophages (using nanoparticles) or the production of interleukin-1 beta (using inhibitors against protein kinases, NOD-like receptor protein-3, or P2X7) may potentially be employed to treat these types of lung inflammation without affecting the natural immune response to bacterial infections.

Gender difference in plasma fatty-acid-binding protein 4 levels in patients with chronic obstructive pulmonary disease

Plasma FABP4 levels were higher in females with COPD compared with both males with COPD and healthy females. FABP4 levels correlated inversely with lung function, and positively with adiponectin and TNFα in COPD.

COPD (chronic obstructive pulmonary disease) is characterized by airway inflammation and increases the likelihood of the development of atherosclerosis. Recent studies have indicated that FABP4 (fatty-acid-binding protein 4), an intracellular lipid chaperone of low molecular mass, plays an important role in the regulation of inflammation and atherosclerosis. We carried out a preliminary clinical study aiming at investigating the relationships between circulating FABP4 levels in patients with COPD and inflammation and lung function. We enrolled 50 COPD patients and 39 healthy controls in the study. Lung function tests were performed in all subjects. Plasma levels of FABP4 and adiponectin, TNFα (tumour necrosis factor α) and CRP (C-reactive protein) were measured. The correlations between FABP4 and lung function, adipokine (adiponectin), inflammatory factors and BMI (body mass index) were analysed. Compared with both males with COPD and healthy females, plasma FABP4 levels in females with COPD were significantly increased. Adiponectin and CRP levels were significantly higher in patients with COPD. Furthermore, we found that FABP4 levels were inversely correlated with FEV₁% predicted (FEV₁ is forced expiratory volume in 1 s) and positively correlated with adiponectin and TNFα in COPD patients. In addition, a positive correlation between plasma FABP4 and CRP was found in females with COPD. However, FABP4 levels were not correlated with BMI. Our results underline a gender difference in FABP4 secretion in stable COPD patients. Further studies are warranted to clarify the exact role of FABP4 in the pathogenesis of COPD.

Neutrophil extracellular traps are associated with inflammation in chronic airway disease

BACKGROUND AND OBJECTIVE

Neutrophil extracellular traps (NETs) are web-like structures comprising DNA and antimicrobial proteins, expelled from neutrophils during NETosis. Persistence of NETs can be pro-inflammatory, yet their role in respiratory disease remains unclear. This study aimed to investigate the presence of NETs in sputum from patients with asthma and COPD, and the relationship of NETs with inflammatory phenotype and disease severity.

METHODS

Induced sputum was collected from healthy controls, asthma and COPD patients. Extracellular DNA (eDNA) was quantified by PicoGreen. LL-37, α-defensins1-3, NE, IL-1β and CXCL8 were quantified by ELISA. PAD4 and NLRP3 gene expression was performed using qPCR. NETs were imaged in sputum smears using immunofluorescence microscopy.

RESULTS

Sputum eDNA and NET neutrophil antimicrobial proteins were significantly elevated in asthma and COPD compared with healthy controls. Levels of eDNA and NET components were significantly higher in neutrophilic versus non-neutrophilic asthma and COPD. NETs were clearly visualized in sputum smears. PAD4 mRNA was upregulated in neutrophilic COPD. The level of eDNA was higher in severe asthma. High eDNA levels were associated with heightened innate immune responses, including elevated CXCL8 and IL-1β, and NLRP3 gene expression in both COPD and asthma. Antimicrobial proteins and eDNA were positively correlated with airway neutrophils, and negatively correlated with lung function and symptoms.

CONCLUSION

NETs are present in the airways of subjects with asthma and COPD. Accumulation of excessive NETs was associated with activation of innate immune responses contributing to disease pathogenesis in chronic airway disease.

Effects of Chung-Pae Inhalation Therapy on a Mouse Model of Chronic Obstructive Pulmonary Disease

Chung-pae (CP) inhalation therapy is a method frequently used in Korea to treat lung disease, especially chronic obstructive pulmonary disease (COPD). This study investigated the effects of CP inhalation on a COPD animal model. C57BL/6 mice received porcine pancreatic elastase (PPE) and lipopolysaccharide (LPS) alternately three times for 3 weeks to induce COPD. Then, CP (5 or 20 mg/kg) was administered every 2 h after the final LPS administration. The effect of CP was evaluated by bronchoalveolar lavage (BAL) fluid analysis, histological analysis of lung tissue, and reverse transcription polymerase chain reaction analysis of mRNA of interleukin- (IL-) 1β, tumor necrosis factor- (TNF-) α, IL-6, and tumor growth factor- (TGF-) β. Intratracheal CP administration reduced the number of leukocytes and neutrophils in BAL fluid, inhibited the histological appearance of lung damage, and decreased the mRNA levels of the proinflammatory cytokines IL-1β, TNF-α, IL-6, and TGF-β. Intratracheal CP administration effectively decreased the chronic inflammation and pathological changes in a PPE- and LPS-induced COPD mouse model. Therefore, we suggest that CP is a promising strategy for COPD.

S-maltoheptaose targets syndecan-bound effectors to reduce smoking-related neutrophilic inflammation

Cigarette smoke induces injury and neutrophilic inflammation in the airways of smokers. The stability and activity of inflammatory effectors, IL8 and neutrophil elastase (NE), can be prolonged by binding to airway heparan sulfate (HS)/syndecan-1, posing risk for developing chronic obstructive pulmonary disease(COPD). We hypothesize that antagonizing HS/syndecan-1 binding of the inflammatory effectors could reduce smoking-related neutrophil-mediated airway inflammation. Analysis of bronchoalveolar lavage fluid(BALF) of COPD patients found both total and unopposed NE levels to be significantly higher among smokers with COPD than non-COPD subjects. Similar NE burden was observed in smoke-exposed rats compared to sham air controls. We chose sulfated-maltoheptaose(SM), a heparin-mimetic, to antagonize HS/sydecan-1 binding of the inflammatory mediators in airway fluids and lung tissues of the smoke-exposed rat model. Airway treatment with SM resulted in displacement of CINC-1 and NE from complexation with bronchio-epithelial HS/syndecan-1, dissipating the chemokine gradient for neutrophil flux across to the bronchial lumen. Following SM displacement of NE from shed HS/syndecan-1 in bronchial fluids, NE became accessible to inhibition by α₁-antitrypsin endogenous in test samples. The antagonistic actions of SM against syndecan-1 binding of NE and CINC-1 in smoke-exposed airways suggest new therapeutic opportunities for modulating airway inflammation in smokers with SM delivery.

Neutrophil proteases alter the interleukin-22-receptor-dependent lung antimicrobial defence

Chronic obstructive pulmonary disease (COPD) is punctuated by episodes of infection-driven acute exacerbations. Despite the life-threatening nature of these exacerbations, the underlying mechanisms remain unclear, although a high number of neutrophils in the lungs of COPD patients is known to correlate with poor prognosis. Interleukin (IL)-22 is a cytokine that plays a pivotal role in lung antimicrobial defence and tissue protection. We hypothesised that neutrophils secrete proteases that may have adverse effects in COPD, by altering the IL-22 receptor (IL-22R)-dependent signalling.Using in vitro and in vivo approaches as well as reverse transcriptase quantitative PCR, flow cytometry and/or Western blotting techniques, we first showed that pathogens such as the influenza virus promote IL-22R expression in human bronchial epithelial cells, whereas Pseudomonas aeruginosa, bacterial lipopolysaccharide or cigarette smoke do not. Most importantly, neutrophil proteases cleave IL-22R and impair IL-22-dependent immune signalling and expression of antimicrobial effectors such as β-defensin-2. This proteolysis resulted in the release of a soluble fragment of IL-22R, which was detectable both in cellular and animal models as well as in sputa from COPD patients with acute exacerbations.Hence, our study reveals an unsuspected regulation by the proteolytic action of neutrophil enzymes of IL-22-dependent lung host response. This process probably enhances pathogen replication, and ultimately COPD exacerbations.

Comparison of neutrophil infiltration between type 1 and type 2 autoimmune pancreatitis

BACKGROUND

Characteristics of type 2 autoimmune pancreatitis (AIP) is granulocyte epithelial lesions, called idiopathic duct-centric pancreatitis (IDCP). To clarify pathogenesis of IDCP, we investigated mechanism of neutrophil infiltration in type 1 AIP, called lymphoplasmacytic sclerosing pancreatitis (LPSP) and IDCP.

METHOD

This study was performed on resected pancreata from patients with alcoholic chronic pancreatitis (ACP, n = 10), LPSP (n = 10) and IDCP (n = 12). The number of neutrophils around the pancreatic ducts was counted. The expression of neutrophils chemoattractants granulocyte chemotactic protein-2 (GCP-2) and interleukin-8 (IL-8) in the pancreatic duct epithelia was examined using immunohistochemistry. The cell staining intensity is scored as negative (0), weak (1), moderate (2) or strong (3).

RESULTS

The median number of neutrophils around the interlobular pancreatic ducts was significantly higher in IDCP (15.16; interquartile range [IQR]: 9.74-18.41) than in ACP (2.66; IQR: 1.33-4.33) (P < 0.05) and LPSP (3.16; IQR: 2.74-4.57) (P < 0.01). There was no significant difference in the median number of neutrophils around the intralobular pancreatic ducts among ACP (1.16; IQR: 0.33-3.41), LPSP (3.16; IQR: 0.74-5.5) and IDCP (3.00; IQR: 1.08-7.91). The median score of GCP-2 in the interlobular pancreatic duct epithelia was significantly higher in IDCP (1.5; IQR: 0.25-2) than in ACP (0; IQR: 0-0.75) (P < 0.05) and LPSP (0; IQR: 0-0.75) (P < 0.05). There was no significant difference in the median score of IL-8 in the interlobular pancreatic duct epithelia among ACP (0; IQR: 0-0.75), LPSP (1; IQR: 0-1.75) and IDCP (0.5; IQR: 0-1).

CONCLUSIONS

Significantly increased neutrophil infiltration around the interlobular pancreatic duct in IDCP may depend on GCP-2.

Molecular pathogenesis of cigarette smoking-induced stable COPD

Inflammation is a central feature of stable chronic obstructive pulmonary disease (COPD) and involves both activation of structural cells of the airways and the lungs and the activation and/or recruitment of infiltrating inflammatory cells. This results in enhanced expression of many pro-inflammatory proteins and reduced expression of some anti-inflammatory mediators. An altered protein expression is generally associated with concomitant changes in gene expression profiles in a cell-specific manner. Increased understanding of the role of transcription factors and of the signaling pathways leading to their activation in stable COPD will provide new targets to enable the development of potential anti-inflammatory drugs. Several new compounds targeting these pathways and/or transcription factors are now in development for the treatment of stable COPD. Furthermore, glucocorticoids drugs already in clinical use act through their own transcription factor, the glucocorticoid receptor, to control the expression of inflammatory and anti-inflammatory genes.