Impact of the Junction Adhesion MoleculeA on Asthma

Purpose@#Junctional adhesion molecule (JAM)-A is an immunoglobulin-like molecule that colocalizes with tight junctions (TJs) in the endothelium and epithelium. It is also found in blood leukocytes and platelets. The biological significance of JAM-A in asthma, as well as its clinical potential as a therapeutic target, are not well understood. The aim of this study was to elucidate the role of JAM-A in a mouse model of asthma, and to determine blood levels of JAM-A in asthmatic patients. @*Materials and Methods@#Mice sensitized and challenged with ovalbumin (OVA) or saline were used to investigate the role of JAM-A in the pathogenesis of bronchial asthma. In addition, JAM-A levels were measured in the plasma of asthmatic patients and healthy controls. The relationships between JAM-A and clinical variables in patients with asthma were also examined. @*Results@#Plasma JAM-A levels were higher in asthma patients (n=19) than in healthy controls (n=12). In asthma patients, the JAM-A levels correlated with forced expiratory volume in 1 second (FEV1%), FEV1/forced vital capacity (FVC), and the blood lymphocyte proportion. JAM-A, phospho-JNK, and phospho-ERK protein expressions in lung tissue were significantly higher in OVA/OVA mice than in control mice. In human bronchial epithelial cells treated with house dust mite extracts for 4 h, 8 h, and 24 h, the JAMA, phospho-JNK, and phospho-ERK expressions were increased, as shown by Western blotting, while the transepithelial electrical resistance was reduced. @*Conclusion@#These results suggest that JAM-A is involved in the pathogenesis of asthma, and may be a marker for asthma.

N-acetylcysteine decreases airway inflammation and responsiveness in asthma by modulatingclaudin 18 expression

Background/Aims@#N-acetylcysteine (NAC) affects signaling pathways involved in apoptosis, angiogenesis, cell growth and arrest, redox-regulated gene expression, and the inflammatory response. However, it is not known how the signal mechanism for tight junctional protein claudin (CLDN) 18 is regulated in asthma patients. @*Methods@#To investigate the effects of NAC on CLDN18 expression in a mouse model of asthma, and to assess plasma levels of CLDN18 in asthma patients. A murine model of asthma induced by ovalbumin (OVA) was established using wild-type BALB/c female mice, and the levels of CLDNs, phosphorylated-pyruvate dehydrogenase kinase 1 (p-PDK1), and protein kinase B (Akt) pathway proteins following NAC treatment were examined by Western blotting and immunohistochemistry. In addition, the plasma levels of CLDN18 were evaluated in asthmatic patients and control subjects. @*Results@#NAC diminished OVA-induced airway hyper-responsiveness and inflammation.Levels of CLDN18 protein were higher in lung tissue from OVA mice than tissue from control mice, and were increased by treatment with NAC or dexamethasone. Treatment with NAC or dexamethasone decreased the OVA-induced increase in interleukin-1α protein levels. Although treatment with NAC increased OVA-induced p-PDK1 protein levels, it decreased phosphorylated Akt (pAkt)/Akt levels. Soluble CLDN18 levels were lower in patients with asthma than in controls and were correlated with the percentage of neutrophils, forced expiratory volume in 1 second (FEV1)/forced vital capacity % (FVC%) and FEV1%. @*Conclusions@#CLDN18 plays a role in the pathogenesis of asthma and NAC diminishes airway inflammation and responsiveness by modulating CLDN18 expression.

Serum Calprotectin Is a Potential Marker in Patients with Asthma

Background@#Calprotectin is the major cytosolic protein in neutrophil granulocytes.Although asthma is known to cause eosinophilic inflammation, some patients with asthma have non-eosinophilic inflammation, which is characterized by local neutrophilic inflammation. The aim of this study was to assess calprotectin expression levels in a mouse model of asthma, and to observe the relationship of serum calprotectin level and clinical variables in patients with asthma. @*Methods@#Mice were sensitized and challenged with 10 μg and 20 μg of Aspergillus fumigatus, respectively; mice treated with saline were used as a control. The levels of calprotectin were determined using enzyme-linked immunosorbent assay, immunoblotting, and immunohistochemical analysis. The serum levels of calprotectin were also assessed in patients with asthma. The relationship between calprotectin and clinicopathological characteristics was determined. @*Results@#Calprotectin, S100A8, and S100A9 expression was elevated in the mouse lungs, Calprotectin levels were higher in the serum of patients with asthma (n = 33) compared with those of healthy individuals (n = 28). Calprotectin levels correlated with forced expiratory volume in one second/forced vital capacity (r = −0.215, P = 0.043), smoke amount (r = 0.413, P = 0.017), body mass index (r = −0.445,P= 0.000), and blood neutrophil percentage (r = 0.300, P = 0.004) in patients with asthma. @*Conclusion@#Our data suggest that calprotectin could potentially be used as a biomarker for asthma.

Impact of the Endothelial Tight Junction Protein Claudin-5 on Clinical Profiles of Patients With COPD

PURPOSE: The tight junction protein claudin-5 (CLDN5) is critical to the control of endothelial cellular polarity and pericellular permeability. The role of CLDN5 in chronic obstructive pulmonary disease (COPD) remains unclear. The aim of this study was to investigate the association between CLDN5 levels and clinical variables in patients with COPD. METHODS: In total, 30 patients with COPD and 30 healthy controls were enrolled in the study. The plasma CLDN5 level was checked in patients with stable or exacerbated COPD and in healthy controls. RESULTS: The mean plasma CLDN5 level of patients with COPD was 0.63 ± 0.05 ng/mL and that of healthy controls was 6.9 ± 0.78 ng/mL (P = 0.001). The mean plasma CLDN5 level was 0.71 ± 0.05 ng/mL in exacerbated COPD patients and 0.63 ± 0.04 ng/mL in patients with stable COPD (P < 0.05). The plasma CLDN5 level among COPD subjects was correlated with the smoking amount (r = −0.530, P = 0.001). The plasma CLDN5 level in stable COPD patients was correlated with forced expiratory volume in one second (FEV1, %pred.) (r = −0.481, P = 0.037). CONCLUSIONS: The plasma CLDN5 level was not correlated with age. CLDN5 may be involved in the pathogenesis of COPD. Further studies having a larger sample size will be needed to clarify CLDN5 in COPD.

Methacholine bronchial provocation test in patients with asthma: serial measurements and clinical significance

BACKGROUND/AIMS: The methacholine bronchial provocation test (MBPT) is used to detect and quantify airway hyper-responsiveness (AHR). Since improvements in the severity of asthma are associated with improvements in AHR, clinical studies of asthma therapies routinely use the change of airway responsiveness as an objective outcome. The aim of this study was to assess the relationship between serial MBPT and clinical profiles in patients with asthma. METHODS: A total of 323 asthma patients were included in this study. The MBPT was performed on all patients beginning at their initial diagnosis until asthma was considered controlled based on the Global Initiative for Asthma guidelines. A responder was defined by a decrease in AHR while all other patients were considered non-responders. RESULTS: A total of 213 patients (66%) were responders, while 110 patients (34%) were non-responders. The responder group had a lower initial PC20 (provocative concentration of methacholine required to decrease the forced expiratory volume in 1 second by 20%) and longer duration compared to the non-responder group. Members of the responder group also had superior qualities of life, compared to members of the non-responder group. Whole blood cell counts were not related to differences in PC20; however, eosinophil concentration was. No differences in sex, age, body mass index, smoking history, serum immunoglobulin E, or frequency of acute exacerbation were observed between responders and non-responders. CONCLUSIONS: The initial PC20, the duration of asthma, eosinophil concentrations, and quality-of-life may be useful variables to identify improvements in AHR in asthma patients.

Alteration in Claudin-4 Contributes to Airway Inflammation and Responsiveness in Asthma

PURPOSE: Claudin-4 has been reported to function as a paracellular sodium barrier and is one of the 3 major claudins expressed in lung alveolar epithelial cells. However, the possible role of claudin-4 in bronchial asthma has not yet been fully studied. In this study, we aimed to elucidate the role of claudin-4 in the pathogenesis of bronchial asthma. METHODS: We determined claudin-4 levels in blood from asthmatic patients. Moreover, using mice sensitized and challenged with OVA, as well as sensitized and challenged with saline, we investigated whether claudin-4 is involved in the pathogenesis of bronchial asthma. Der p1 induced the inflammatory cytokines in NHBE cells. RESULTS: We found that claudin-4 in blood from asthmatic patients was increased compared with that from healthy control subjects. Plasma claudin-4 levels were significantly higher in exacerbated patients than in control patients with bronchial asthma. The plasma claudin-4 level was correlated with eosinophils, total IgE, FEV1% pred, and FEV1/FVC. Moreover, lung tissues from the OVA-OVA mice showed significant increases in transcripts and proteins of claudin-4 as well as in TJ breaks and the densities of claudin-4 staining. When claudin-4 was knocked down by transfecting its siRNA, inflammatory cytokine expressions, which were induced by Der p1 treatment, were significantly increased. CONCLUSIONS: These findings thus raise the possibility that regulation of lung epithelial barrier proteins may constitute a therapeutic approach for asthma.

Effect of TiO₂ Nanoparticles on Inflammasome-Mediated Airway Inflammation and Responsiveness

PURPOSE: Nanoparticles (NPs) may cause cell and tissue damage, leading to local and systemic inflammatory responses and adverse effects on health due to the inhalation of particulate matter. The inflammasome is a major regulator of inflammation through its activation of pro-caspase-1, which cleaves pro-interleukin-1β (pro-IL-1β) into its mature form and may induce acute and chronic immune responses to NPs. However, little is known about the response of the inflammasome to NP exposure via the airways in asthma. The aim of this study was to identify the impact of titanium dioxide (TiO2) NPs on inflammasome in a mouse model of allergic asthma. METHODS: Mice were treated with ovalbumin (OVA) or TiO₂ NPs. IL-1β, IL-18, NAIP, CIITA, HET-E, TP-2 (NACHT), leucine-rich repeat (LRR), pyrin domain-containing protein 3 (NLRP3), and caspase-1 were assessed by Western blotting. Caspase-1 was assessed by immunohistochemistry (IHC). Levels of reactive oxygen species (ROS)—as markers of oxidative damage—and the mediators 8-isoprostane and carbonyl were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Airway hyperresponsiveness (AHR) and inflammation were increased in OVA-sensitized/challenged mice, and these responses were exacerbated by exposure to TiO₂ NPs. NP treatment increased IL-1β and IL-18 expression in OVA-sensitized/challenged mice. NPs augmented the expression of NLRP3 and caspase-1, leading to production of active caspase-1 in the lung. Caspase-1 expression was increased and exacerbated by TiO₂ NP exposure in OVA-sensitized/challenged mice. ROS levels tended to be increased in OVA-sensitized/challenged and OVA-sensitized/challenged-plus-TiO₂ NP-exposed mice. CONCLUSIONS: Our data demonstrated that inflammasome activation occured in asthmatic lungs following NP exposure, suggesting that targeting the inflammasome may assist in controling NP-induced airway inflammation and hyperresponsiveness.

Long-Term Effects of Diesel Exhaust Particles on Airway Inflammation and Remodeling in a Mouse Model

PURPOSE: Diesel exhaust particles (DEPs) can induce and trigger airway hyperresponsiveness (AHR) and inflammation. The aim of this study was to investigate the effect of long-term DEP exposure on AHR, inflammation, lung fibrosis, and goblet cell hyperplasia in a mouse model. METHODS: BALB/c mice were exposed to DEPs 1 hour a day for 5 days a week for 3 months in a closed-system chamber attached to a ultrasonic nebulizer (low dose: 100 microg/m3 DEPs, high dose: 3 mg/m3 DEPs). The control group was exposed to saline. Enhanced pause was measured as an indicator of AHR. Animals were subjected to whole-body plethysmography and then sacrificed to determine the performance of bronchoalveolar lavage and histology. RESULTS: AHR was higher in the DEP group than in the control group, and higher in the high-dose DEP than in the low-dose DEP groups at 4, 8, and 12 weeks. The numbers of neutrophils and lymphocytes were higher in the high-dose DEP group than in the low-dose DEP group and control group at 4, 8, and 12 weeks. The levels of interleukin (IL)-5, IL-13, and interferon-gamma were higher in the low-dose DEP group than in the control group at 12 weeks. The level of IL-10 was higher in the high-dose DEP group than in the control group at 12 weeks. The level of vascular endothelial growth factor was higher in the low-dose and high-dose DEP groups than in the control group at 12 weeks. The level of IL-6 was higher in the low-dose DEP group than in the control group at 12 weeks. The level of transforming growth factor-beta was higher in the high-dose DEP group than in the control group at 4, 8, and 12 weeks. The collagen content and lung fibrosis in lung tissue was higher in the high-dose DEP group at 8 and 12 weeks. CONCLUSIONS: These results suggest that long-term DEP exposure may increase AHR, inflammation, lung fibrosis, and goblet cell hyperplasia in a mouse model.