Cyclooxygenase-1 overexpression decreases Basal airway responsiveness but not allergic inflammation

Pharmacological inhibition or genetic disruption of cyclooxygenase (COX)-1 or COX-2 exacerbates the inflammatory and functional responses of the lung to environmentally relevant stimuli. To further examine the contribution of COX-derived eicosanoids to basal lung function and to allergic lung inflammation, transgenic (Tr) mice were generated in which overexpression of human COX-1 was targeted to airway epithelium. Although no differences in basal respiratory or lung mechanical parameters were observed, COX-1 Tr mice had increased bronchoalveolar lavage fluid PGE(2) content compared with wild-type littermates (23.0 +/- 3.6 vs 8.4 +/- 1.4 pg/ml; p < 0.05) and exhibited decreased airway responsiveness to inhaled methacholine. In an OVA-induced allergic airway inflammation model, comparable up-regulation of COX-2 protein was observed in the lungs of allergic wild-type and COX-1 Tr mice. Furthermore, no genotype differences were observed in allergic mice in total cell number, eosinophil content (70 vs 76% of total cells, respectively), and inflammatory cytokine content of bronchoalveolar lavage fluid, or in airway responsiveness to inhaled methacholine (p > 0.05). To eliminate the presumed confounding effects of COX-2 up-regulation, COX-1 Tr mice were bred into a COX-2 null background. In these mice, the presence of the COX-1 transgene did not alter allergen-induced inflammation but significantly attenuated allergen-induced airway hyperresponsiveness, coincident with reduced airway leukotriene levels. Collectively, these data indicate that COX-1 overexpression attenuates airway responsiveness under basal conditions but does not influence allergic airway inflammation.     

A constituent of Alpinia katsumadai suppresses allergic airway inflammation

Two new compounds, named as (3R)-5,7-dihydroxy-3-isopropyl-3-methylisochroman-1-one (1), and (1R,3R,4S)-1-(4′-methyl-phenyl)-3,4-dihydro-3,4-dimethyl-1H-2-benzopyran-5,6,8-triol (2), were isolated from seeds of Alpinia katsumadai Hayata. Structures of compounds 1 and 2 were elucidated and determined on the basis of spectroscopic analysis. Additionally, compound 1 significantly suppressed allergic airway inflammation induced by OVA through reducing airway hyperresponsiveness. Moreover, the inflammation suppression was associated with a marked decrease in the Th2 cytokines and IgE production.     

Sulfatide-activated type II NKT cells prevent allergic airway inflammation by inhibiting type I NKT cell function in a mouse model of asthma

Asthma is a common chronic inflammatory disease involving many different cell types. Recently, type I natural killer T (NKT) cells have been demonstrated to play a crucial role in the development of asthma. However, the roles of type II NKT cells in asthma have not been investigated before. Interestingly, type I and type II NKT cells have been shown to have opposing roles in antitumor immunity, antiparasite immunity, and autoimmunity. We hypothesized that sulfatide-activated type II NKT cells could prevent allergic airway inflammation by inhibiting type I NKT cell function in asthma. Strikingly, in our mouse model, activation of type II NKT cells by sulfatide administration and adoptive transfer of sulfatide-activated type II NKT cells result in reduced-inflammation cell infiltration in the lung and bronchoalveolar lavage fluid, decreased levels of IL-4 and IL-5 in the BALF; and decreased serum levels of ovalbumin-specific IgE and IgG1. Furthermore, it is found that the activation of sulfatide-reactive type II NKT cells leads to the functional inactivation of type I NKT cells, including the proliferation and cytokine secretion. Our data reveal that type II NKT cells activated by glycolipids, such as sulfatide, may serve as a novel approach to treat allergic diseases and other disorders characterized by inappropriate type I NKT cell activation.     

Differential expression and function of breast regression protein 39 (BRP-39) in murine models of subacute cigarette smoke exposure and allergic airway inflammation

Background

While the presence of the chitinase-like molecule YKL40 has been reported in COPD and asthma, its relevance to inflammatory processes elicited by cigarette smoke and common environmental allergens, such as house dust mite (HDM), is not well understood. The objective of the current study was to assess expression and function of BRP-39, the murine equivalent of YKL40 in a murine model of cigarette smoke-induced inflammation and contrast expression and function to a model of HDM-induced allergic airway inflammation.

Methods

CD1, C57BL/6, and BALB/c mice were room air- or cigarette smoke-exposed for 4 days in a whole-body exposure system. In separate experiments, BALB/c mice were challenged with HDM extract once a day for 10 days. BRP-39 was assessed by ELISA and immunohistochemistry. IL-13, IL-1R1, IL-18, and BRP-39 knock out (KO) mice were utilized to assess the mechanism and relevance of BRP-39 in cigarette smoke- and HDM-induced airway inflammation.

Results

Cigarette smoke exposure elicited a robust induction of BRP-39 but not the catalytically active chitinase, AMCase, in lung epithelial cells and alveolar macrophages of all mouse strains tested. Both BRP-39 and AMCase were increased in lung tissue after HDM exposure. Examining smoke-exposed IL-1R1, IL-18, and IL-13 deficient mice, BRP-39 induction was found to be IL-1 and not IL-18 or IL-13 dependent, while induction of BRP-39 by HDM was independent of IL-1 and IL-13. Despite the importance of BRP-39 in cellular inflammation in HDM-induced airway inflammation, BRP-39 was found to be redundant for cigarette smoke-induced airway inflammation and the adjuvant properties of cigarette smoke.

Conclusions

These data highlight the contrast between the importance of BRP-39 in HDM- and cigarette smoke-induced inflammation. While functionally important in HDM-induced inflammation, BRP-39 is a biomarker of cigarette smoke induced inflammation which is the byproduct of an IL-1 inflammatory pathway.     

The signaling adapter p62 is an important mediator of T helper 2 cell function and allergic airway inflammation

Na?ve T helper (Th) cells differentiate in response to antigen stimulation into either Th1 or Th2 effector cells, which are characterized by the secretion of different set of cytokines. Th2 differentiation, which is critical for allergic airway disease, is triggered by signals of the T-cell receptor (TCR) and the cytokines generated during polarization, particularly IL-4. We determine here the potential role of the signaling adapter p62 in T-cell polarization. We report using p62-/- mice and cells that p62 acts downstream TCR activation, and is important for Th2 polarization and asthma, playing a significant role in the control of the sustained activation of NF-kappaB and late synthesis of GATA3 and IL-4 by participating in the activation of the IKK complex.     

Schistosoma japonicum peptide SJMHE1 suppresses airway inflammation of allergic asthma in mice

Helminths and their products can shape immune responses by modulating immune cells, which are dysfunctional in inflammatory diseases such as asthma. We previously identified SJMHE1, a small molecule peptide from the HSP60 protein of Schistosoma japonicum. SJMHE1 can inhibit delayed‐type hypersensitivity and collagen‐induced arthritis in mice. In the present study, we evaluated this peptide's potential intervention effect and mechanism on ovalbumin‐induced asthma in mice. SJMHE1 treatment suppressed airway inflammation in allergic mice, decreased the infiltrating inflammatory cells in the lungs and bronchoalveolar lavage fluid, modulated the production of pro‐inflammatory and anti‐inflammatory cytokines in the splenocytes and lungs of allergic mice, reduced the percentage of Th2 cells and increased the proportion of Th1 and regulatory T cells (Tregs). At the same time, Foxp3 and T‐bet expression increased, and GATA3 and RORγt decreased in the lungs of allergic mice. We proved that SJMHE1 can interrupt the development of asthma by diminishing airway inflammation in mice. The down‐regulation of Th2 response and the up‐regulation of Th1 and Tregs response may contribute to the protection induced by SJMHE1 in allergic mice. SJMHE1 can serve as a novel therapy for asthma and other allergic or inflammatory diseases.     

TLR2 agonist ameliorates established allergic airway inflammation by promoting Th1 response and not via regulatory T cells

TLRs are primary sensors of both innate and adaptive immune systems, where they play a pivotal role in the response directed against structurally conserved components of pathogens. Synthetic bacterial lipopeptide Pam3CSK4 is a TLR2 agonist capable of modulating Th1 and Th2 responses. This study examines the therapeutic effect of Pam3CSK4 in established airway inflammation in a murine model of asthma. In mice previously sensitized and challenged with OVA, Pam3CSK4 given i.p. markedly reduced the total inflammatory cell infiltrate and eosinophilia in bronchoalveolar lavage fluid. Pam3CSK4 therapy was associated with a reduction in OVA-induced IL-4 and IL-5 secretion from thoracic lymph node culture, airways inflammation, bronchial hyperresponsiveness, and serum levels of IgE. Pam3CSK4 therapy was also associated with an increase in OVA-induced IFN-gamma, IL-12, and IL-10 production. However, the anti-inflammatory effect of Pam3CSK4 was independent of IL-10 or TGF-beta, but was critically dependent on IL-12, the production of which by dendritic cells was enhanced by Pam3CSK4 in vitro. Our results provide direct evidence that Pam3CSK4 could represent a novel therapeutic agent in allergic airways disease.     

Impact of cigarette smoke on T and B cell responsiveness

Although its direct effects cannot be discounted, tobacco's effects on the immune system have been proposed to play a key role in mediating its deleterious health impact. Studies in rats using high levels of smoke exposure have suggested that tobacco smoke exhausts cellular signal transduction cascades, making lymphocytes unresponsive to stimulation. In the present study, we show that purified B or T cells, and total lymphocytes from the lungs, lymph nodes and spleens of smoke-exposed mice fluxed calcium, proliferated, and secreted immunoglobulin or IFN-gamma similarly to control mice when stimulated with ligands including anti-IgM, and anti-CD3. Importantly, we recapitulated these findings in PBMCs from human smokers; cells from long-term smokers and never-smokers proliferated equivalently when stimulated ex vivo. Previous reports of lymphocyte unresponsiveness in rats are inconsistent with these findings, and may reflect a phenomenon observed only at levels of smoke exposure well above those seen in actual human smokers.     

Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function

Background

Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFα and IL-1β, rather than as regulatory cytokine.

Objective

To investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease.

Methods

Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects.

Results

The levels of the proinflammatory biomarkers TNFα and IL-1β were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p < 0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p < 0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (r_S = 0.53, p < 0.05).

Conclusions

In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.     

Interleukin-10 suppresses natural killer cell but not natural killer T cell activation during bacterial infection

Interleukin (IL)-10 is an anti-inflammatory cytokine known to modulate the outcome of sepsis by decreasing pro-inflammatory cytokine production, including IL-12, a main activator of natural killer (NK) cells. We hypothesized that neutralization of IL-10 would increase NK and natural killer T (NKT) cell activation through increased IL-12 in a mouse model of bacterial peritonitis. NK and NKT cell activations were measured by CD69 expression on NK1.1+/CD3- and NK1.1+/CD3+ cells after cecal ligation and puncture (CLP). NK cells were significantly more activated in mice treated with anti-IL-10 antibodies, whereas no such effect was observed in NKT cells. Similarly, intracellular interferon gamma (IFN-gamma) levels were increased in NK cells of anti-IL-10-treated mice, but not in NKT cells. IL-12 and IL-18 levels were increased in both CLP groups, but in anti-IL-10-treated mice, early IL-12 and late IL-18 levels were significantly higher than in controls. Survival at 18 h after CLP was lower in anti-IL-10 mice, which was associated with increased liver neutrophil accumulation. In summary, these data show an activating effect of IL-10 on NK, but not on NKT cells after CLP, which corresponded with decreased survival, higher IFN-gamma production, and increased remote organ neutrophil accumulation. These effects were not mediated by IL-12 and IL-18 alone, and reinforce a role for NK cells in remote organ dysfunction following peritonitis.     

Prolonged cigarette smoke exposure alters mitochondrial structure and function in airway epithelial cells

Background

Cigarette smoking is the major risk factor for COPD, leading to chronic airway inflammation. We hypothesized that cigarette smoke induces structural and functional changes of airway epithelial mitochondria, with important implications for lung inflammation and COPD pathogenesis.

Methods

We studied changes in mitochondrial morphology and in expression of markers for mitochondrial capacity, damage/biogenesis and fission/fusion in the human bronchial epithelial cell line BEAS-2B upon 6-months from ex-smoking COPD GOLD stage IV patients to age-matched smoking and never-smoking controls.

Results

We observed that long-term CSE exposure induces robust changes in mitochondrial structure, including fragmentation, branching and quantity of cristae. The majority of these changes were persistent upon CSE depletion. Furthermore, long-term CSE exposure significantly increased the expression of specific fission/fusion markers (Fis1, Mfn1, Mfn2, Drp1 and Opa1), oxidative phosphorylation (OXPHOS) proteins (Complex II, III and V), and oxidative stress (Mn-SOD) markers. These changes were accompanied by increased levels of the pro-inflammatory mediators IL-6, IL-8, and IL-1β. Importantly, COPD primary bronchial epithelial cells (PBECs) displayed similar changes in mitochondrial morphology as observed in long-term CSE-exposure BEAS-2B cells. Moreover, expression of specific OXPHOS proteins was higher in PBECs from COPD patients than control smokers, as was the expression of mitochondrial stress marker PINK1.

Conclusion

The observed mitochondrial changes in COPD epithelium are potentially the consequence of long-term exposure to cigarette smoke, leading to impaired mitochondrial function and may play a role in the pathogenesis of COPD.     

Inert 50-nm polystyrene nanoparticles that modify pulmonary dendritic cell function and inhibit allergic airway inflammation

Nanoparticles are being developed for diverse biomedical applications, but there is concern about their potential to promote inflammation, particularly in the lung. Although a variety of ambient, anthropogenic and man-made nanoparticles can promote lung inflammation, little is known about the long-term immunomodulatory effects of inert noninflammatory nanoparticles. We previously showed polystyrene 50-nm nanoparticles coated with the neutral amino acid glycine (PS50G nanoparticles) are not inflammatory and are taken up preferentially by dendritic cells (DCs) in the periphery. We tested the effects of such nanoparticles on pulmonary DC function and the development of acute allergic airway inflammation. Surprisingly, exposure to PS50G nanoparticles did not exacerbate but instead inhibited key features of allergic airway inflammation including lung airway and parenchymal inflammation, airway epithelial mucus production, and serum allergen-specific IgE and allergen-specific Th2 cytokines in the lung-draining lymph node (LN) after allergen challenge 1 mo later. PS50G nanoparticles themselves did not induce lung oxidative stress or cardiac or lung inflammation. Mechanistically, PS50G nanoparticles did not impair peripheral allergen sensitization but exerted their effect at the lung allergen challenge phase by inhibiting expansion of CD11c(+)MHCII(hi) DCs in the lung and draining LN and allergen-laden CD11b(hi)MHCII(hi) DCs in the lung after allergen challenge. PS50G nanoparticles further suppressed the ability of CD11b(hi) DCs in the draining LN of allergen-challenged mice to induce proliferation of OVA-specific CD4(+) T cells. The discovery that a defined type of nanoparticle can inhibit, rather than promote, lung inflammation via modulation of DC function opens the door to the discovery of other nanoparticle types with exciting beneficial properties.     

Pharmacological targeting of anaphylatoxin receptors during the effector phase of allergic asthma suppresses airway hyperresponsiveness and airway inflammation

Airway hyperresponsiveness and airway inflammation are hallmarks of allergic asthma, the etiology of which is crucially linked to the presence of Th2 cytokines. A role for the complement anaphylatoxins C3a and C5a in allergic asthma was suggested, as deficiencies of the C3a receptor (C3aR) and of complement factor C5 modulate airway hyperresponsiveness, airway inflammation, and Th2 cytokine levels. However, such models do not allow differentiation of effects on the sensitization phase and the effector phase of the allergic response, respectively. In this study, we determined the role of the anaphylatoxins on the effector phase of asthma by pharmacological targeting of the anaphylatoxin receptors. C3aR and C5a receptor (C5aR) signaling was blocked using the nonpeptidic C3aR antagonist SB290157 and the neutralizing C5aR mAb 20/70 in a murine model of Aspergillus fumigatus extract induced pulmonary allergy. Airway hyperresponsiveness was substantially improved after C5aR blockade but not after C3aR blockade. Airway inflammation was significantly reduced in mice treated with the C3aR antagonist or the anti-C5aR mAb, as demonstrated by reduced numbers of neutrophils and eosinophils in bronchoalveolar lavage fluid. Of note, C5aR but not C3aR inhibition reduced lymphocyte numbers in bronchoalveolar lavage fluid. Cytokine levels of IL-5 and IL-13 in bronchoalveolar lavage fluid were not altered by C3aR or C5aR blockade. However, blockade of both anaphylatoxin receptors markedly reduced IL-4 levels. These data suggest an important and exclusive role for C5aR signaling on the development of airway hyperresponsiveness during pulmonary allergen challenge, whereas both anaphylatoxins contribute to airway inflammation and IL-4 production.     

NF-kappa B activation in airways modulates allergic inflammation but not hyperresponsiveness

Airways display robust NF-kappaB activation and represent targets for anti-inflammatory asthma therapies, but the functional importance of NF-kappaB activation in airway epithelium remains enigmatic. Therefore, transgenic mice were created in which NF-kappaB activation is repressed specifically in airways (CC10-IkappaBalpha(SR) mice). In response to inhaled Ag, transgenic mice demonstrated significantly ameliorated inflammation, reduced levels of chemokines, T cell cytokines, mucus cell metaplasia, and circulating IgE compared with littermate controls. Despite these findings, Ag-driven airways hyperresponsiveness was not attenuated in CC10-IkappaBalpha(SR) mice. This study clearly demonstrates that airway epithelial NF-kappaB activation orchestrates Ag-induced inflammation and subsequent adaptive immune responses, but does not contribute to airways hyperresponsiveness, the cardinal feature that underlies asthma.     

Reduction in Ames Salmonella mutagenicity of mainstream cigarette smoke condensate by tobacco protein removal

The mutagenic activity of cigarette smoke condensates (CSC) made from tobacco before and after removal of protein was assessed by the Ames Salmonella assay in bacterial strains TA98 and TA100. Removal of protein and peptides from flue-cured tobacco via water extraction followed by protease digestion reduced the mutagenicity of the resultant CSC by 80% in the TA98 strain and 50% in the TA100 strain. Similarly, reductions of 81% in TA98 and 54% in TA100 were seen following water extraction and protease digestion of burley tobacco. The significant reductions in Ames mutagenicity following protein removal suggest that protein pyrolysis products are a principal contributor to the genotoxicity of CSC as measured in this assay.     

Nix/BNIP3L-dependent mitophagy accounts for airway epithelial cell injury induced by cigarette smoke

Cigarette smoke-induced airway epithelial cell mitophagy is an important mechanism in the pathogenesis of chronic obstructive pulmonary disease (COPD). Mitochondrial protein Nix (also known as BNIP3L) is a selective autophagy receptor and participates in several human diseases. However, little is known about the role of Nix in airway epithelial cell injury during the development of COPD. The aim of the present study is to investigate the effects of Nix on mitophagy and mitochondrial function in airway epithelial cells exposed to cigarette smoke extract (CSE). Our present study has found that CSE could increase Nix protein expression and induce mitophagy in airway epithelial cells. And Nix siRNA significantly inhibited mitophagy and attenuated mitochondrial dysfunction and cell injury when airway epithelial cells were stimulated with 7.5% CSE. In contrast, Nix overexpression enhanced mitophagy and aggravated mitochondrial dysfunction and cell injury when airway epithelial cells were incubated with 7.5% CSE. These data suggest that Nix-dependent mitophagy promotes airway epithelial cell and mitochondria injury induced by cigarette smoke, and may be involved in the pathogenesis of COPD and other cigarette smoke-associated diseases.     

Micropolyspora faeni causes airway inflammation but not hyperresponsiveness in sensitized ponies

We assessed the effect of aerosol Micropolyspora faeni challenge in two groups of ponies by measuring lung function, airway reactivity to aerosol histamine, and bronchoalveolar lavage fluid cytology. One group of ponies was sensitized by subcutaneous injection of M. faeni in complete Freund's adjuvant, and the other group served as control. In both groups of ponies, measurements were made at base line and 5 h after aerosol administration of 30 ml of saline or 30 ml of 1% wt/vol particulate M. faeni antigen in saline. Saline challenge had no effect on any of the measured variables. M. faeni challenge had no effect on pulmonary mechanics or gas exchange in the control group but significantly increased respiratory frequency and minute ventilation and decreased arterial CO2 tension in the sensitized ponies. In both groups of ponies, aerosol M. faeni challenge significantly increased total white blood cell count and neutrophil numbers in bronchoalveolar lavage fluid while large mononuclear cell numbers decreased. Airway responsiveness was unaltered by saline or M. faeni challenge in both pony groups. We conclude that aerosol M. faeni challenge induces pulmonary neutrophilia and abnormalities of ventilation but is not accompanied by airway hyperresponsiveness in sensitized ponies.