Induce Mucus Hypersecretion Research Articles

Sestrin2/Keap1/Nrf2 pathway regulates mucus hypersecretion in pulmonary epithelium induced by traffic-related PM2.5 and water-soluble extracts

The involvement of fine particulate matter (PM2.5) exposure in the progression of asthma has been extensively discussed in epidemiological and experimental evidence, which aroused widespread attention. Asthma is characterized by mucus hypersecretion. This study investigates the underlying toxic mechanism of traffic-related PM2.5 (TRPM2.5) and water-soluble extracts (WSE) on mucus hypersecretion in the lungs of rats with asthma and 16HBE cells. The ovalbumin-induced rats were administrated by instillation of TRPM2.5 and WSE in the trachea once three days for eight times. The results showed that TRPM2.5 and WSE had an adverse impact on mucus secretion. Specifically, conspicuous mucus stains and increased goblet cells in the bronchial epithelium by PAS staining were found in lung tissues of rats with asthma; MUC5AC gene and protein expression levels in lung tissues of rats with asthma and 16HBE cells were elevated. In addition, TRPM2.5 and WSE triggered oxidative damage via upregulation of malondialdehyde and myeloperoxidase as well as activation of the Sestrin2/Keap1/Nrf2 signaling pathway. Conversely, the knockdown of Sestrin2 effectively inhibited TRPM2.5 and WSE-induced mucus hypersecretion, oxidative stress, and Keap1/Nrf2 signaling pathway and its downstream target gene NQO1. Collectively, it was demonstrated that TRPM2.5 and WSE induced mucus hypersecretion mediated by the Sestrin2/Keap1/Nrf2 pathway.

Exogenous Lipoxin A4 attenuates IL4-induced Mucin Expression in Human Airway Epithelial Cells.

Introduction: The proinflammatory cytokine interleukin-4 (IL-4) induces mucus hypersecretion by human airway epithelial cells and the MAP kinase signalling pathway may be important in terms of IL-4-induced MUC5AC gene expression. Lipoxin A4 (LXA4) is an arachidonic acid-derived mediator that promotes inflammation by binding to the anti-inflammatory receptors (ALXs) or the formyl-peptide receptor like-1 (FPRL1) protein expressed by airway epithelial cells. Here, we explore the effects of LXA4 on IL-4-induced mucin gene expression in, and secretion from, human airway epithelial cells. Methods: We co-treated cells with IL-4 (20 ng/mL) and LXA4 (1 nM) and measured the expression levels of mRNAs encoding MUC5AC and 5B via real-time polymerase chain reaction; protein expression levels were determined by Western blotting and immunocytofluorescence. The ability of IL-4 and LXA4 to suppress protein expression was determined by Western blotting. Results: IL-4 increased MUC5AC and 5B gene and protein expression. LXA4 suppressed IL-4-induced MUC5AC and 5B gene and protein expression by interacting with the IL4 receptor and mitogen-activated protein kinase (MAPK) pathway, including both phospho-p38 MAPK and phospho-extracellular signal-regulated kinase (phospho-ERK). IL-4 and LXA4 increased and decreased, respectively, the number of cells that stained with anti-MUC5AC and 5B antibodies. Conclusions: LXA4 may regulate mucus hypersecretion induced by IL4 in human airway epithelial cells.

ITGB4 deficiency induces mucus hypersecretion by upregulating MUC5AC in RSV-infected airway epithelial cells.

Respiratory syncytial virus (RSV) infection is the main cause of bronchiolitis in children. Excessive mucus secretion is one of the primary symbols in RSV related lower respiratory tract infections (RSV-related LRTI), which is closely associated with the occurrence and development of asthma in later life. Integrin β4 (ITGB4) is down-regulated in the airway epithelial cells (AECs) of asthma patients which plays a critical role in the pathogenesis of asthma. However, whether ITGB4 is involved in the pathological processes of RSV infection remains unclear. In this study, we found that decreased expression of ITGB4 was negatively correlated with the level of MUC5AC in childhood AECs following RSV infection. Moreover, ITGB4 deficiency led to mucus hypersecretion and MUC5AC overexpression in the small airway of RSV-infected mice. MUC5AC expression was upregulated by ITGB4 in HBE cells through EGFR, ERK and c-Jun pathways. EGFR inhibitors treatment inhibited mucus hypersecretion and MUC5AC overexpression in ITGB4-deficient mice after RSV infection. Together, these results demonstrated that epithelial ITGB4 deficiency induces mucus hypersecretion by upregulating the expression of MUC5AC through EGFR/ERK/c-Jun pathway, which further associated with RSV-related LRTI.

The Aryl Hydrocarbon Receptor in Asthma: Friend or Foe?

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that has emerged as an important player in asthma control. AhR is responsive to environmental molecules and endogenous or dietary metabolites and regulates innate and adaptive immune responses. Binding of this receptor by different ligands has led to seemingly opposite responses in different asthma models. In this review, we present two sides of the same coin, with the beneficial and deleterious roles of AhR evaluated using known endogenous or exogenous ligands, deficient mice or antagonists. On one hand, AhR has an anti-inflammatory role since its activation in dendritic cells blocks the generation of pro-inflammatory T cells or shifts macrophages toward an anti-inflammatory M2 phenotype. On the other hand, AhR activation by particle-associated polycyclic aromatic hydrocarbons from the environment is pro-inflammatory, inducing mucus hypersecretion, airway remodelling, dysregulation of antigen presenting cells and exacerbates asthma features. Data concerning the role of AhR in cells from asthmatic patients are also reviewed, since AhR could represent a potential target for therapeutic immunomodulation.

Pic Protein From Enteroaggregative E. coli Induces Different Mechanisms for Its Dual Activity as a Mucus Secretagogue and a Mucinase.

A hallmark of enteroaggregative Escherichia coli (EAEC) infection is the formation of an intestinal biofilm, which comprises a mucus layer with immersed bacteria. Pic is an autotransporter secreted by EAEC, and other E. coli pathotypes, and has been involved in two apparently contradictory phenotypes, as a mucus secretagogue and as a mucinase. Here, we investigated this Pic dual activity, mucus secretagogue capability and mucinolytic activity, in human goblet cells that secrete MUC2 and MUC5AC. Pic induced mucus hypersecretion directly in the goblet cells, without other intestinal cell types involved. At the same time, Pic exhibited strong proteolytic activity on the secreted mucins. These activities were independent since a mutation in the serine protease motif (PicS258I) abolished mucin degradation while maintaining the mucus secretagogue activity intact. Furthermore, deoxycholic acid (DCA)-induced mucins were proteolytically degraded when goblet cells were co-incubated with DCA/Pic, while co-incubation with DCA/PicS258I induced a synergistic effect on mucus hypersecretion. Pic was more efficient degrading MUC5AC than MUC2, but no degradation was detected with Pic inactivated at the active site by mutation or pharmacological inhibition. Remarkably, Pic cleaved MUC2 and MUC5AC in the C-terminal domain, leaving N-terminal subproducts, impacting the feature of gel-forming mucins and allowing mucus layer penetration by EAEC. Astonishingly, Pic stimulated rapid mucin secretion in goblet-like cells by activating the intracellular calcium pathway resulting from the PLC signal transduction pathway, leading to the production of DAG and releasing IP3, a second messenger of calcium signaling. Therefore, the dual activity of Pic, as a mucus secretagogue and a mucinase, is relevant in the context of carbon source generation and mucus layer penetration, allowing EAEC to live within the layer of mucus but also access epithelial cells.

Role of p62/SQSTM1 in lipopolysaccharide (LPS)-induced mucus hypersecretion in bronchial epithelial cells

AimsThe aims of this study were to evaluate the effects of p62/SQSTM1 expression levels on lipopolysaccharide (LPS)-induced mucus secretion in BEAS-2B bronchial epithelial cells by measuring expression levels of the MUC5AC gene and the Mucin-5AC (MUC5AC) protein. Materials and methodsBronchial epithelial cells, BEAS-2B, were treated with LPS at different time points. Rapamycin, an autophagy agonist, was added to the BEAS-2B cells 30 min before LPS treatment. Lentivirus transfection was then used to knock down the expression of p62/SQSTM1 (Sequestosome 1) to investigate changes in the downstream signaling pathway. Western blotting and immunofluorescence were used to study the expression levels of MUC5AC, and reverse transcription-polymerase chain reaction (RT-PCR) was used to study the expression of MUC5AC mRNA. Key findingsLPS treatment of BEAS-2B cells inhibited autophagy, activated the nuclear factor kappa B (NF-κB) signaling pathway and increased the expression of MUC5AC. The autophagy agonist, rapamycin, activated autophagy, inhibited the NF-κB signaling pathway and decreased LPS-induced expression of MUC5AC. Knockdown of p62/SQSTM1 expression reduced activation of the NF-κB signaling pathway and reduced LPS-induced mucus secretion by BEAS-2B cells in vitro. SignificanceIn this in vitro study, which utilized BEAS-2B bronchial epithelial cells, p62/SQSTM1 was shown to have a role in LPS-induced mucus hypersecretion by activating the NF-κB signaling pathway.

An Adeno-Associated Viral Vector Capable of Penetrating the Mucus Barrier to Inhaled Gene Therapy

Diffusion of the viral vectors evaluated in inhaled gene therapy clinical trials to date are largely hindered within airway mucus, which limits their access to, and transduction of, the underlying airway epithelium prior to clearance from the lung. Here, we discovered that adeno-associated virus (AAV) serotype 6 was able to rapidly diffuse through mucus collected from cystic fibrosis (CF) patients, unlike previously tested AAV serotypes. A point mutation of the AAV6 capsid suggests a potential mechanism by which AAV6 avoids adhesion to the mucus mesh. Significantly greater transgene expression was achieved with AAV6 compared to a mucoadhesive serotype, AAV1, in air-liquid interface cultures of human CF bronchial epithelium with naturally secreted mucus or induced mucus hypersecretion. In addition, AAV6 achieved superior distribution and overall level of transgene expression compared to AAV1 in the airways and whole lungs, respectively, of transgenic mice with airway mucus obstruction. Our findings motivate further evaluation and clinical development of AAV6 for inhaled gene therapy.

Cerebral ischemia/reperfusion injury induces airway mucus hypersecretion in rats and activates IL‑13‑associated inflammatory mechanisms.

The majority of patients that suffer a stroke have excessive sputum, which accelerates the development of pulmonary complications. However, it is unclear whether cerebral ischemia and reperfusion (I/R) injury induces mucus hypersecretion, and the potential role of inflammation remains unknown. In the present study, the reversible middle cerebral artery occlusion model was applied in rats to induce cerebral I/R injury. The rats were grouped according to the duration of reperfusion (6, 12, 24, 48 and 72h). Neurological dysfunction was evaluated by Longa scoring and lung dry‑to‑wet weight (dw/ww) ratios were determined to reflect the degree of mucus secretion. Inflammatory factor interleukin‑13 (IL‑13) and tumor necrosis factor‑α (TNF‑α) levels in serum and bronchoalveolar lavage fluid (BALF) were determined by enzyme‑linked immunosorbent assay. Pulmonary levels of mucin 5AC (MUC5AC) and key molecules involved in nuclear factor‑κB (NF‑κB) signaling were determined by western blotting and immunohistochemistry. Rats with cerebral I/R had impaired neurological function, which was associated with the length of reperfusion time. In addition, the dw/ww lung ratio decreased and the pulmonary expression of MUC5AC increased with the increase in severity of neurological dysfunction, indicating that cerebral I/R may induce mucus hypersecretion in a reperfusion time‑dependent manner. IL‑13 and TNF‑α levels in serum and BALF, as well as the nuclear translocation of NF‑κB p65 in pulmonary tissues, significantly increased following cerebral I/R, which suggests that the activation of IL‑13 and NF‑κB inflammatory pathways may be involved. The present study concluded that cerebral I/R injury may induce airway mucus hypersecretion by activating IL‑13 and NF‑κB inflammatory pathways.

Increased expression of hCLCA1 in chronic rhinosinusitis and its contribution to produce MUC5AC.

Mucus hypersecretion is a hallmarks of chronic rhinosinusitis. The expression of MUC5AC, a major respiratory mucin gene, is increased in chronic rhinosinusitis. The mechanisms inducing mucus hypersecretion have not been fully evaluated in chronic rhinosinusitis. Human Ca2+ -activated Cl- channel 1 (hCLCA1) is implicated in the regulation of mucus production, airway fluid, and electrolyte transport. The present study objectives was to investigate the expression of hCLCA1 in chronic rhinosinusitis and evaluate whether its level is altered by stimulation with type 1 T helper (Th1) and Th2 cytokines, and to determine the possible role of hCLCA1 on the regulation of mucin 5AC (MUC5AC) production. Controlled prospective study. The expression of hCLCA1 and MUC5AC in normal and inflammatory ethmoid mucosa was determined by real-time polymerase chain reaction, immunohistochemistry, and Western blot. In cultured cells, the expression of hCLCA1 and MUC5AC was measured after stimulation with Th1 and Th2 cytokines. In a supernatant, the MUC5AC level was analyzed using enzyme-linked immunosorbent assay after treatment with niflumic acid. The levels of hCLCA1 and MUC5AC were increased in chronic rhinosinusitis, irrespective of nasal polyp presence, where they were distributed in superficial epithelial cells and submucosal glands. In cultured cells treated with interleukin (IL)-9, IL-4, IL-13, tumor necrosis factor-α, transforming growth factor-β, interferon-γ, and IL-1β, the expression of hCLCA1 and MUC5AC was increased. In cells treated with niflumic acid, the production of MUC5AC was inhibited. The current findings indicate that the expression of hCLCA1 is increased in chronic rhinosinusitis and may be regulated by Th1 and Th2 cytokines, possibly contributing to the production of MUC5AC. NA Laryngoscope, 126:E347-E355, 2016.

Entamoeba histolytica Cysteine Proteinase 5 Evokes Mucin Exocytosis from Colonic Goblet Cells via αvβ3 Integrin.

Critical to the pathogenesis of intestinal amebiasis, Entamoeba histolytica (Eh) induces mucus hypersecretion and degrades the colonic mucus layer at the site of invasion. The parasite component(s) responsible for hypersecretion are poorly defined, as are regulators of mucin secretion within the host. In this study, we have identified the key virulence factor in live Eh that elicits the fast release of mucin by goblets cells as cysteine protease 5 (EhCP5) whereas, modest mucus secretion occurred with secreted soluble EhCP5 and recombinant CP5. Coupling of EhCP5-αvβ3 integrin on goblet cells facilitated outside-in signaling by activating SRC family kinases (SFK) and focal adhesion kinase that resulted in the activation/phosphorlyation of PI3K at the site of Eh contact and production of PIP3. PKCδ was activated at the EhCP5-αvβ3 integrin contact site that specifically regulated mucin secretion though the trafficking vesicle marker myristoylated alanine-rich C-kinase substrate (MARCKS). This study has identified that EhCP5 coupling with goblet cell αvβ3 receptors can initiate a signal cascade involving PI3K, PKCδ and MARCKS to drive mucin secretion from goblet cells critical in disease pathogenesis.

Erythronium japonicum attenuates histopathological lung abnormalities in a mouse model of ovalbumin-induced asthma.

Asthma is a chronic lung condition that can induce mucus hypersecretion and pulmonary obstruction and may even cause death, particularly in children and older individuals. Erythronium japonicum (E. japonicum) is a traditional herb used in Korea and East Asian countries that has been found to exert free radical scavenging activity and anti-proliferative effects in human colorectal carcinoma cells. In the present study, we evaluated the anti-asthmatic effects of an extract of E. japonicum in a mouse model of ovalbumin (OVA)-induced asthma. Female BALB/c mice were sensitized with an intraperitoneal injection of OVA and aluminum hydroxide hydrate on days 1 and 8 and then received the following treatments on days 21 to 25: i) control (no treatment), ii) sterilized tap water (given orally), iii) 1 mg/kg/day dexamethasone (administered orally), iv) 60 mg/kg/day E. japonicum extract, and v) 600 mg/kg/day E. japonicum extract. On the same days, all the mice except those in the control group were challenged 1 h later with nebulized 5% OVA for 30 min. We found that treatment with E. japonicum extract suppressed the OVA-induced increase in the number of white blood cells and decreased the IgE level in the bronchoalveolar lavage fluid samples obtained from the mice. Histopathological analysis of the lung tissues revealed that E. japonicum attenuated the asthma-related morphological changes in the mouse lung tissue, including the increased secretion of mucus in the bronchioles, eosinophil infiltration around the bronchioles and vessels, and goblet cell and epithelial cell hyperplasia. Immunohistochemical analysis revealed that treatment with E. japonicum extract suppressed the OVA-induced proliferation of T helper cells (CD4+) and B cells (CD19+) in the mouse lung tissue. Furthermore, treatment with E. japonicum extract modulated the expression of both T helper 2 cell-related factors [GATA binding protein 3 (GATA-3), tumor necrosis factor-α (TNF-α), interleukin (IL)-4, IL-5, IL-6 and IL-13], as well as that of T helper 1 cell-related factors [(interferon-γ (IFN-γ), IL-12p35 and IL-12p40]. These findings suggest that E. japonicum may potentially be used as an anti-asthmatic treatment.

Influence of hot-humid stress and acclimation on airway mucus production in lungs of mice

To study the change of airway mucus secretion under a high temperature and humidity environment, and explore the effects of hot-humid stress and acclimation on the morbidity and mortality of respiratory disease. Forty-five BABL/c mice were randomly divided into five groups:normal group, hot-humid group I, hot-humid group Ⅱ, hot-humid group Ⅲ, hot-humid group IV, with 9 mice in each group. Mice in normal group were continuously placed in the common environment and sacrificed after 7 days. Mice in other groups were housed in a temperature-and-humidity-controlled environment (33℃±0.5℃, 95%±5%). Mice in hot-humid group I, hot-humid group Ⅱ, hot-humid group Ⅲ and hot-humid group IV were sacrificed after 12 hours, 24 hours, 4 days, 7 days respectively. The protein expression of mucin 5AC(MUC5AC)、epidermal growth factor receptor (EGFR)、aquaporin 1(AQP1) and aquaporin 5(AQP5) in lung were tested by immunohistochemisty. After housed in a high temperature and humidity environment, immunohistochemisty revealed a significant increase of AQP5 12 h later, MUC5AC and EGFR 24 h later, compared with normal group(P<0.05). There was a significant decrease of MUC5AC 7 d later, compared with normal group(P<0.05). There was no significant difference in MUC5AC, EGFR and AQP5 expression among all groups at other time points. There was no difference of AQP1 in humid heat groups, compared with normal group, but a significant decrease in humid heat Ⅲ and IV groups, compared with humid heat I and Ⅱ groups. These findings indicate that hot-humid stress induces mucus hypersecretion in airways, which may be related to the up-regulation of EGFR and down-regulation of AQP5 in MUC5AC. Although acclimation mitigates above-mentioned response, a series of more complex responses may be induced if still in the hot-humid environment.

Thick airway surface liquid volume and weak mucin expression in pendrin-deficient human airway epithelia.

Pendrin is an anion exchanger whose mutations are known to cause hearing loss. However, recent data support the linkage between pendrin expression and airway diseases, such as asthma. To evaluate the role of pendrin in the regulation of the airway surface liquid (ASL) volume and mucin expression, we investigated the function and expression of pendrin and ion channels and anion exchangers. Human nasal epithelial cells were cultured from 16 deaf patients carrying pendrin mutations (DFNB4) and 17 controls. The cells were treated with IL-13 to induce mucus hypersecretion. Airway surface liquid thickness was measured and real-time polymerase chain reaction was performed targeting various transporters and MUC5AC. Anion exchanger activity was measured using a pH-sensitive fluorescent probe. Periodic acid-Schiff staining was performed on the cultured cells and inferior turbinate tissues. The ASL layer of the nasal epithelia from DFNB4 subjects was thicker than the controls, and the difference became more prominent following IL-13 stimulation. There was no difference in anion exchange activity after IL-13 treatment in the cells from DFNB4 patients, while it increased in the controls. Goblet cell metaplasia induced by IL-13 treatment seen in the controls was not observed in the DFNB4 cells. Furthermore, the periodic acid-Schiff staining-positive area was lesser in the inferior turbinate tissues from DFNB4 patients that those from controls. Pendrin plays a critical role in ASL volume regulation and mucin expression as pendrin-deficient airway epithelial cells are refractory to stimulation with IL-13. Specific blockers targeting pendrin in the airways may therefore have therapeutic potential in the treatment of allergic airway diseases.

β2-Adrenoceptor involved in smoking-induced airway mucus hypersecretion through β-arrestin-dependent signaling.

Progression of chronic obstructive pulmonary disease is associated with small airway obstruction by accumulation of inflammatory mucous exudates. However, the mechanism of mucin hypersecretion after exposure to cigarette smoke (CS) is still not clear. In this study, we explored the contribution of β2-adrenoceptor (β2-AR) signaling to CS extract (CSE)-induced mucus hypersecretion in vitro and examined the effect of a β-blocker on airway mucin hypersecretion in vivo. NCI-H292 epithelial cell line was used to determine the contribution of β2-AR signaling to CSE-induced MUC5AC production by treatment with β2-AR antagonists propranolol and ICI118551 and β2-AR-targeted small interfering RNA. The effect of propranolol on airway mucus hypersecretion was examined in a rat model exposed to CS. MUC5AC expression was assayed by real-time PCR, immunohistochemistry and ELISA. β2-AR and its downstream signaling were detected by western blot analysis. We found that pretreating NCI-H292 cells with propranolol, ICI118551 for 30 min or β2AR–targeted siRNA for 48 h reduced MUC5AC mRNA and protein levels stimulated by CSE. However,inhibiting the classical β2AR–cAMP-PKA pathway didn’t attenuate CSE-induced MUC5AC production, while silencing β-arretin2 expression significantly decreased ERK and p38MAPK phosphorylation, thus reduced the CSE-stimulated MUC5AC production. In vivo, we found that administration of propranolol (25 mg kg−1d−1) for 28 days significantly attenuated the airway goblet cell metaplasia, mucus hypersecretion and MUC5AC expression of rats exposed to CS. From the study, β2-AR–β-arrestin2–ERK1/2 signaling was required for CS-induced airway MUC5AC expression. Chronic propranolol administration ameliorated airway mucus hypersecretion and MUC5AC expression in smoking rats. The exploration of these mechanisms may contribute to the optimization of β2-AR target therapy in chronic obstructive pulmonary disease.

Hypoxia-mediated mechanism of MUC5AC production in human nasal epithelia and its implication in rhinosinusitis.

BackgroundExcessive mucus production is typical in various upper airway diseases. In sinusitis, the expression of MUC5AC, a major respiratory mucin gene, increases. However, the mechanisms leading to mucus hypersecretion in sinusitis have not been characterized. Hypoxia due to occlusion of the sinus ostium is one of the major pathologic mechanisms of sinusitis, but there have been no reports regarding the mechanism of hypoxia-induced mucus hypersecretion.Methods and FindingsThis study aims to identify whether hypoxia may induce mucus hypersecretion and elucidate its mechanism. Normal human nasal epithelial (NHNE) cells and human lung mucoepidermoid carcinoma cell line (NCI-H292) were used. Sinus mucosa from patients was also tested. Anoxic condition was in an anaerobic chamber with a 95% N2/5% CO2 atmosphere. The regulatory mechanism of MUC5AC by anoxia was investigated using RT-PCR, real-time PCR, western blot, ChIP, electrophoretic mobility shift, and luciferase assay. We show that levels of MUC5AC mRNA and the corresponding secreted protein increase in anoxic cultured NHNE cells. The major transcription factor for hypoxia-related signaling, HIF-1α, is induced during hypoxia, and transfection of a mammalian expression vector encoding HIF-1α results in increased MUC5AC mRNA levels under normoxic conditions. Moreover, hypoxia-induced expression of MUC5AC mRNA is down-regulated by transfected HIF-1α siRNA. We found increased MUC5AC promoter activity under anoxic conditions, as indicated by a luciferase reporter assay, and mutation of the putative hypoxia-response element in MUC5AC promoter attenuated this activity. Binding of over-expressed HIF-1α to the hypoxia-response element in the MUC5AC promoter was confirmed. In human sinusitis mucosa, which is supposed to be hypoxic, expression of MUC5AC and HIF-1α is higher than in control mucosa.ConclusionThe results indicate that anoxia up-regulates MUC5AC by the HIF-1α signaling pathway in human nasal epithelia and suggest that hypoxia might be a pathogenic mechanism of mucus hypersecretion in sinusitis.

T helper cells plasticity in inflammation

CD4+ T cells can be subdivided from a functional point of view into two main subsets: effector cells, which provide protection against exogenous offending agents, and regulatory T (Treg) cells whose function is to avoid autoimmune reactions and to stop the effector response against exogenous antigens, when the response itself becomes dangerous for the host. Human effector CD4+ T lymphocytes can be additionally classified into lineages based mainly on their immunological functions that are supported by distinct profile of cytokine, transcription factor, and homing receptors expression. In the last years, beyond the well known populations of human T helper (Th) lymphocytes, Th1 and Th2 cells, other populations have been discovered and phenotypically characterized. These include the Th17 subset, which is certainly the most intensively studied, but also Th22, Th9, and T follicular helper (Tfh) lymphocytes. In addition to their protective functions, these T helper populations are also involved in the pathogenesis of several inflammatory immune-mediated disorders. Th1 and Th17 cells are involved in the pathogenesis of organ-specific autoimmune diseases and other chronic inflammatory disorders, whereas allergen-specific Th2 lymphocytes play a crucial role in allergy. Although classically viewed as distinct lineages, recent evidence indicate that CD4+ T cells, particularly the Th17 subset, are more plastic than previously thought. It is not fully understood how often such plasticity occurs in the course of physiologic responses to pathogens and what its importance is in protective immunity, but in inflammatory conditions Th17 lymphocytes that have shifted towards a Th1 or Th2 phenotype, acquiring the ability to produce IFN-γ or IL-4, and seem to be particularly aggressive and more pathogenic than the unshifted cells. In this context, the possibility to interfere with this modulation of phenotype can be considered a possible target for developing novel therapeutic strategies in the above mentioned diseases.

The activin A antagonist follistatin inhibits asthmatic airway remodelling

BackgroundCurrent pharmacotherapy is highly effective in the clinical management of the majority of patients with stable asthma, however severe asthma remains inadequately treated. Prevention of airway remodelling is a major...

Acrolein effects in pulmonary cells: relevance to chronic obstructive pulmonary disease

Acrolein (2-propenal) is a highly reactive α,β-unsaturated aldehyde and a respiratory irritant that is ubiquitously present in the environment but that can also be generated endogenously at sites of inflammation. Acrolein is abundant in tobacco smoke, which is the major environmental risk factor for chronic obstructive pulmonary disease (COPD), and elevated levels of acrolein are found in the lung fluids of COPD patients. Its high electrophilicity makes acrolein notorious for its facile reaction with biological nucleophiles, leading to the modification of proteins and DNA and depletion of antioxidant defenses. As a consequence, acrolein results in oxidative stress as well as altered intracellular signaling and gene transcription/translation. In pulmonary cells, acrolein, at subtoxic concentrations, can activate intracellular stress kinases, alter the production of inflammatory mediators and proteases, modify innate immune response, induce mucus hypersecretion, and damage airway epithelium. A better comprehension of the mechanisms underlying acrolein effects in the airways may suggest novel treatment strategies in COPD.

Flagellin/TLR5 responses induce mucus hypersecretion by activating EGFR via an epithelial cell signaling cascades

Mucus hypersecretion is an important manifestation in patients with chronic inflammatory airway diseases. Excessive production of mucin leads to airway mucus obstruction and contributes to morbidity and mortality in these diseases. The molecular mechanisms underlying mucin overproduction, however, still remain largely unknown. Here, we report that the bacterium Pseudomonas aeruginosa (P. aeruginosa), an important human respiratory pathogen, induced MUC5AC mucin expression via an epithelial cell signaling cascade in human airway epithelial cells. The flagellin purified from P. aeruginosa up-regulated MUC5AC expression by activating its receptor Toll-like receptor 5 (TLR5) in 16HBE cells. This effect was inhibited by NADPH oxidase inhibitor (DPI), small interfering RNA of dual oxidase 2 (Duox2) and reactive oxygen species (ROS) scavengers (nPG and DMSO). Flagellin induced TGF-α release, and stimulated phosphorylated epidermal growth factor receptor (EGFR) and MUC5AC overproduction. These effects were prevented by EGFR and TGF-α neutralizing antibodies, metalloprotease inhibitors (GM6001 and TNF-α protease inhibitor-1) and specific knockdown of TNF-α-converting enzyme (TACE) with TACE siRNA. These findings may bring new insights into the molecular pathogenesis of P. aeruginosa infections and lead to novel therapeutic intervention for mucin overproduction in patients with P. aeruginosa infections.

N-acetylcysteine Enhances Cystic Fibrosis Sputum Penetration and Airway Gene Transfer by Highly Compacted DNA Nanoparticles

For effective airway gene therapy of cystic fibrosis (CF), inhaled gene carriers must first penetrate the hyperviscoelastic sputum covering the epithelium. Whether clinically studied gene carriers can penetrate CF sputum remains unknown. Here, we measured the diffusion of a clinically tested nonviral gene carrier, composed of poly-l-lysine conjugated with a 10 kDa polyethylene glycol segment (CK(30)PEG(10k)). We found that CK(30)PEG(10k)/DNA nanoparticles were trapped in CF sputum. To improve gene carrier diffusion across sputum, we tested adjuvant regimens consisting of N-acetylcysteine (NAC), recombinant human DNase (rhDNase) or NAC together with rhDNase. While rhDNase alone did not enhance gene carrier diffusion, NAC and NAC + rhDNase increased average effective diffusivities by 6-fold and 13-fold, respectively, leading to markedly greater fractions of gene carriers that may penetrate sputum layers. We further tested the adjuvant effects of NAC in the airways of mice with Pseudomonas aeruginosa lipopolysaccharide (LPS)-induced mucus hypersecretion. Intranasal dosing of NAC prior to CK(30)PEG(10k)/DNA nanoparticles enhanced gene expression by up to ~12-fold compared to saline control, reaching levels observed in the lungs of mice without LPS challenge. Our findings suggest that a promising synthetic nanoparticle gene carrier may transfer genes substantially more effectively to lungs of CF patients if administered following adjuvant mucolytic therapy with NAC or NAC + rhDNase.