Mucous Cell Metaplasia Research Articles

The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

Inhibition of NOTCH1 Signaling and Glucocorticoid Therapy in T-ALL

Activating mutations in NOTCH1 are present in over 50% of T-cell acute lymphoblastic leukemias (T-ALL). Consequently, inhibition of NOTCH1 signaling with small molecule γ-secretase inhibitors (GSIs) has been proposed as a targeted therapy for this disease. However, GSIs fail to induce robust apoptosis in T-ALL cells and their clinical application has been limited by the development of severe gastrointestinal toxicity (mucous diarrhea and goblet cell metaplasia) resulting from systemic inhibition of NOTCH signaling. Here we show that combination therapy with GSIs plus glucocorticoids can reverse both glucocorticoid resistance in T-ALL and the occurrence of GSI-induced gut toxicity in vivo. The development of glucocorticoid resistance in T-ALL has been associated with the loss of a positive auto-regulatory transcriptional feedback loop required for glucocorticoid induced apoptosis. Using gene expression profiling and ChIP-on-chip analysis we demonstrated that HES1, a transcriptional repressor controlled by NOTCH1, inhibits specific regulatory elements in the glucocorticoid receptor promoter required for effective glucocorticoid receptor autoupregulation and glucocorticoid induced cell death. Consequently, downregulation of HES1 via inhibition of NOTCH1 signaling with GSIs or HES1 inactivation via shRNA knockdown restores glucocorticoid receptor autoupregulation and reverses glucocorticoid resistance in T-ALL cell lines and primary patient samples. Consistent with these results, combination therapy with dexamethasone and GSIs was highly effective in a mouse xenograft model of glucocorticoid resistant T-ALL. Surprisingly, these studies demonstrated not only improved antileukemic responses in mice treated with dexamethasone plus a GSI compared with dexamethasone or placebo treated controls (P<0.05), but also decreased mortality associated with GSI-induced gut toxicity in this model (P<0.01). These results suggested that glucocorticoids may have an enteroprotective effect against GSI-induced gut toxicity. Detailed histological analysis demonstrated a block of proliferation and increased goblet cell numbers in the intestine of GSI treated animals and a moderate increase in proliferation accompanied by increased Paneth cell numbers in the dexamethasone treated group. Notably, cotreatment with dexamethasone plus a GSI completely reversed the induction of goblet cell metaplasia typically induced by systemic inhibition of NOTCH signaling with GSIs. Likewise, dexamethasone also protected RBPJ-K conditional knockout mice, a genetic model of loss of NOTCH signaling, from developing goblet cell metaplasia in the gut. Interestingly, gene expression profiling analysis showed a marked upregulation of cyclin D2 expression in the gut of glucocorticoid treated mice. Moreover, dexamethasone treatment failed to protect Ccnd2 knockout animals from developing GSI-induced metaplasia, demonstrating a critical role of Ccnd2 upregulation in the protective effects of dexamethasone against GSI-induced gut toxicity. Overall, these results uncover a NOTCH1-HES1-glucocorticoid receptor regulatory axis in glucocorticoid resistant T-ALL and demonstrate an unanticipated protective effect of glucocorticoids against GSI-induced gut toxicity. Our studies warrant the clinical testing of glucocorticoids plus GSIs in the treatment of glucocorticoid-resistant T-ALL.

Selective p38&amp;alpha; mitogen-activated protein kinase inhibitor attenuates lung inflammation and fibrosis in IL-13 transgenic mouse model of asthma

p38 Mitogen-activated protein kinase (MAPK) plays a critical role in the activation of inflammatory cells. We investigated the anti-inflammatory effects of a p38α-selective MAPK inhibitor (SD-282) in a mouse transgenic (CC10:IL-13) asthma model. The CC-10-driven over-expression of IL-13 in the mouse lung/airway has been shown to result in a remarkable phenotype recatitulating many features of asthma and characterized by eosinophilic and mononuclear inflammation, with airway epithelial cell hypertrophy, mucus cell metaplasia, the hyperproduction of neutral and acidic mucus, the deposition of Charcot-Leyden-like crystal, and airway sub-epitheilial fibrosis. Here we show how activated p38 MAPK can be observed in the lungs at the onset of asthma ie, around 8 weeks of age in both female and male mice. We also show that administration of a p38α MAPK selective inhibitor, SD-282 at 30 or 90 mg/kg, twice a day for a period of four weeks beginning at the onset of asthma, significantly reduced the inflammation (p < 0.001); hyperplasia of airway epithelium (p < 0.05); goblet cell metaplasia and mucus hypersecretion (p < 0.001) and reduced lung remodeling and fibrosis (p < 0.01), alleviating the severity of lung damage as measured by a composite score (p < 0.05). Furthermore, SD-282 significantly reduced activated p38 MAPK in the lymphocytes and epithelial cells (p < 0.001). Simultaneously, identical studies were conducted with an anti-fibrotic TGFβR1 kinase inhibitor (SD-208) which demonstrated anti-fibrotic but not anti-inflammatory properties. These findings suggest that the p38α-selective MAPK inhibitor may have dual therapeutic potential in attenuating both the inflammatory component and the fibrotic component of asthma and other Th2-polarized inflammatory lung diseases.

Rhinovirus-Induced Major Airway Mucin Production Involves a Novel TLR3-EGFR–Dependent Pathway

Mucociliary clearance is a critical innate defense system responsible for clearing up invading pathogens including bacteria and virus. Although the right amount of mucus is good, excessive mucus causes airway obstruction and tends to precipitate disease symptoms. Rhinovirus (RV) is a common cold virus that causes asthma and chronic obstructive pulmonary disease exacerbation. Mucus overproduction has been linked to the pathogenesis of RV-induced diseases and disease exacerbations. However, the molecular mechanism is not clear. In this study, using one of the major airway mucin-MUC5AC as marker, we found that both major and minor groups of RV induced mucin production in primary human epithelial cells and cell line. RV1A (a minor group of RV) could induce mucous cell metaplasia in vivo. Viral replication was needed for RV-induced mucin expression, and this induction was also dependent on TLR3, suggesting the involvement of double-stranded (ds) RNA signaling. Indeed, dsRNA alone could also induce mucin expression. TLR3-mediated mucin induction was negatively regulated by MyD88, and only partially dependent on TRIF, which suggests a departure from well-documented TLR3 signaling paradigm that mediates inflammatory and other innate defense gene inductions. In addition, TLR3 signaling activated epidermal growth factor receptor (EGFR) through inductions of the expression of EGFR ligands (transforming growth factor-alpha and amphiregulin), which in turn activated EGFR-ERK signaling and mucin expression through an autocrine/paracrine loop. This novel coupling of antiviral defense machinery (i.e., TLR3) and major epithelial proliferation/repair pathway (i.e., EGFR) might play an important role in viral-induced airway remodeling and airway disease exacerbation.

Effect of proteolytic activity ofEpicoccum purpurascensmajor allergen, Epi p 1 in allergic inflammation

Enzymes play an important role in inducing airway inflammation, but knowledge is limited to few proteins. This study was carried out to assess the role of Epi p 1, a serine protease of Epicoccum purpurascens, in inducing allergy and inflammation in a murine model. Balb/c mice were sensitized with Epi p 1 active protease (EAP) or Epicoccum extract. Subsequently, Epi p 1 sensitized mice were boosted on day 14 with EAP or inactivated protease (EIAP). Three intranasal challenges were given and mice were killed to obtain blood, bronchoalveolar lavage fluid (BALF), spleen and lung tissues. Cellular airways infiltration, immunoglobulin E (Ig)E titres and cytokine levels in BALF and splenocyte culture supernatant were compared. Mice immunized with EAP had higher Epi p 1-specific serum IgE and IgG1 than EIAP immunized mice (P < 0.01). There was a twofold difference in the number of eosinophils in BALF of EAP mice and EIAP mice (P < 0.01). A similar trend was recorded for eosinophil peroxidase activity (P < 0.05), indicating the role of proteolytic activity in inducing inflammation. Further, lung histology revealed increased leucocyte infiltration and airway narrowing, with higher inflammation scores in the EAP group than in the EIAP group. The lungs of EAP mice showed increased mucus and goblet cell metaplasia. Interleukin (IL)-4 and IL-5 levels were higher in BALF and splenocyte culture supernatant of EAP mice than in EIAP mice (P < 0.05), indicating a T helper 2 response. Proteolytic activity of Epi p 1 plays an important role in inducing allergic inflammation. The enzymatically inactive form may be investigated for immunotherapy.

Regulation of mucous cell metaplasia in bronchial asthma.

Mucous cell metaplasia (MCM), defined by the appearance of mucous cells in airways where mucous cells were not present, is a consistent pathologic characteristic in the peripheral airways of bronchial asthma. Under mild inflammatory conditions MCM occurs as a result of pre-existing airway epithelial cells (AECs) starting to express mucin genes and differentiating into mucous cells. Under extensive inflammatory responses, AECs proliferate, and the development of MCM involves the differentiation of pre-existing and proliferating cells into mucous cells. Epithelial cell numbers per mm basal lamina are increased by approximately 30%. IL-13 is the central cytokine that is responsible for MCM in asthma through GABA-R- and STAT6-mediated mechanisms involving the calcium-activated chloride channel CLCA. IL-13 is also responsible for the proliferation of AECs by causing cells to produce TGFalpha that acts on the epidermal growth factor (EGF) receptor. Normally, resolution of MCM involves two distinct mechanisms. 1) Some of the metaplastic mucous cells stop the synthesis of mucus and dedifferentiate into Clara or serous cells to reconstitute the epithelium. 2) When proliferation of epithelial cells had occurred, approximately 30% of metaplastic cells are eliminated during the resolution process. Thus, a safe approach to reducing IL-13-induced MCM would involve blocking mucous synthesis and storage, blocking secretion of stored mucus, and eliminating hyperplastic mucous cells. Understanding the molecular mechanisms of each of these processes is necessary for developing effective therapies for reducing mucous hypersecretion in asthma and leading to a repaired epithelium.

Interleukin-10 is an Essential Modulator of Mucoid Metaplasia in a Mouse Otitis Media Model

Inflammatory cytokines are involved in the development of mucous cell metaplasia and hyperplasia (MCM) in otitis media (OM). However, which cytokines play an essential role in the MCM of OM is not clear at the moment. In this study, we hypothesized that interleukin-10 (IL-10) played an indispensable role in the MCM of bacterial OM, and we used IL-10 knockout mice to test this hypothesis. In wild-type mice, both Streptococcus pneumoniae and Haemophilus influenzae triggered the development of MCM in the middle ear mucosa. In IL-10 knockout mice, the number of goblet cells and mucin-producing cells in the middle ear was significantly reduced after bacterial middle ear infection compared with that in wild-type mice. We conclude that IL-10 plays an essential role in the MCM of bacterial OM. Interleukin-10 is a potential target for the treatment of MCM in OM.

Toll like receptor-2 modulates both innate and adaptive immune responses during chronic fungal asthma in mice

We investigated the effect of TLR2 gene deletion in a murine model of chronic fungal asthma. TLR2 wildtype (TLR2(+/+)) and TLR2 deficient (TLR2(-/-)) mice were sensitized to soluble A. fumigatus antigens and challenged with live A. fumigatus conidia, and the extent of allergic airways disease was analyzed in both groups of mice at 3, 7, 14, and 30 days after conidia. At day 7 post-conidia, TLR2(-/-) mice exhibited significantly lower airway hyperresponsiveness, airway inflammation, and whole lung Th2 cytokine levels compared with the TLR2(+ / +) group. TLR2 deletion also significantly reduced mucus cell metaplasia and peribronchial fibrosis at day 30 after conidia. However, fungal material persisted in the TLR2(-/-) group, and at day 30 after conidia TLR2(-/-) mice exhibited enhanced airway neutrophil recruitment and airway hyperresponsiveness. Thus, during chronic fungal asthma in mice, TLR2 is a major contributor to the maintenance of the adaptive Th2-cytokine driven and anti-fungal innate responses.

Maintenance of Airway Hyperresponsiveness in Chronic Asthma May Be Mediated by Th2-Independent Mechanisms

CD4+, Th2-mediated inflammation is an important component of airway hyperresponsiveness (AHR) in allergic airway disease. IL-4 specifically interacts with the Type 1 IL-4 receptor comprised of IL-4Rα and the common γ chain, whereas IL-4 and IL-13 mediate their effects through a common receptor complex made up of IL-4Rα and IL- 13Rα1 (i.e. the Type II IL-4 receptor). In this study, we examined the effects of impaired Th2 signaling on AHR using IL4Rα-/- mice in a murine model of allergic asthma. IL-4Rα-/- mice and control BALB/c (IL-4Rα+/+) mice were sensitized to and challenged with Aspergillus fumigatus. Airway disease was assessed at days 14, 28, 51, and 57 after intratracheal conidia challenge. AHR was evaluated by plethysmography after intravenous methacholine. Whole lung levels of cytokines and chemokines, and serum immunoglobulins were measured by specific ELISA. Paraffin-embedded lung sections were stained for histology. Bronchoalveolar lavage (BAL) fluid was cytospun for differential cell counts. While AHR was significantly reduced in IL-4Rα-/- mice (p&lt;0.01) at days 14 and 28 after conidia challenge, it was increased when compared to controls at later time points (days 51 and 57) even though Th2 cytokines were significantly decreased at day 57, and total IgE and IgG1 levels were markedly decreased throughout the study (p&lt;0.0001). Goblet cell metaplasia was also evident at days 51 and 57 in the knockout groups. These results demonstrate that airway hyperresponsiveness and mucus cell metaplasia in a model of allergic asthma can develop in the absence of a predominant Th2 signaling pathway, suggesting that Th2-independent mechanisms may arbitrate chronic stages of airway disease due to A. fumigatus.

Nonredundant Functions of αβ and γδ T Cells in Acrolein-Induced Pulmonary Pathology

Acrolein exposure represents a significant human health hazard. Repeated acrolein exposure causes the accumulation of monocytes/macrophages and lymphocytes, mucous cell metaplasia, and epithelial injury. Currently, the mechanisms that control these events are unclear, and the relative contribution of T-cell subsets to pulmonary pathologies following repeated exposures to irritants is unknown. To examine whether lymphocyte subpopulations regulate inflammation and epithelial cell pathology, we utilized a mouse model of pulmonary pathology induced by repeated acrolein exposures. The role of lymphocyte subsets was examined by utilizing transgenic mice genetically deficient in either alphabeta T cells or gammadelta T cells, and changes in cellular, molecular, and pathologic outcomes associated with repeated inhalation exposure to 2.0 and 0.5 ppm acrolein were measured. To examine the potential functions of lymphocyte subsets, we purified these cells from the lungs of mice repeatedly exposed to 2.0 ppm acrolein, isolated and amplified messenger RNA, and performed microarray analysis. Our data demonstrate that alphabeta T cells are required for macrophage accumulation, whereas gammadelta T cells are critical regulators of epithelial cell homeostasis, as identified by epithelial cell injury and apoptosis, following repeated acrolein exposure. This is supported by microarray analyses that indicated the T-cell subsets are unique in their gene expression profiles following acrolein exposures. Microarray analyses identified several genes that may contribute to phenotypes mediated by T-cell subpopulations including those involved in cytokine receptor signaling, chemotaxis, growth factor production, lymphocyte activation, and apoptosis. These data provide strong evidence that T-cell subpopulations in the lung are major determinants of pulmonary pathology and highlight the advantages of dissecting their effector functions in response to toxicant exposures.

Expression of the proapoptotic protein Bax is reduced in bronchial mucous cells of asthmatic subjects.

The present studies were designed to determine whether our findings in mice showing that the Bcl-2-associated protein X (Bax), which plays a role in the resolution of allergen-induced mucous cell metaplasia, can be applied to asthma in humans. Immunostaining of autopsy tissues from mild and severe asthmatic subjects showed a significant reduction in the percentage of Bax-positive mucous cells compared with those from nonasthmatic controls. To exclude the possibility that postmortem changes may have affected Bax expression, Bax mRNA levels in airway epithelial cells obtained from nonsmoking asthmatic subjects were compared with those from nonasthmatic controls. Because the number of cells obtained by bronchial brushings is limited, we developed a robust preamplification procedure of cDNA before quantitative real-time PCR to allow detection of 100 gene targets from limited sample size, even when it was prepared from partially degraded RNA. cDNA was prepared by reverse transcription from RNA isolated from bronchial epithelial cells obtained by bronchial brushings from well-characterized subjects without lung disease and from subjects with mild asthma. Quantitative analysis showed that Bax mRNA levels were significantly reduced in samples obtained from asthma patients compared with nonasthma controls. Furthermore, Bax mRNA levels were reduced when primary airway epithelial cells from 10 individuals were treated in culture with the T helper 2 cytokine IL-13. These studies show that Bax expression is reduced in airway epithelial cells of even mild asthmatic subjects and suggest that restoring Bax expression may provide a clinical approach for restoring the normal numbers of epithelial cells and reduced mucous hypersecretion in asthma.

Involvement of the p38 MAPK pathway in IL‐13‐induced mucous cell metaplasia in mouse tracheal epithelial cells

IL-13 has been shown to play a pivotal role in mucous cell metaplasia, which is an important feature of the pathogenesis of asthma. However, the signalling pathways evoked by IL-13 in airway epithelial cells remain unclear. This study investigated the signalling mechanism of IL-13-induced mucous cell metaplasia in primary cultures of mouse tracheal epithelial cells (mTEC). mTEC were cultured in an air-liquid interface system in the presence or absence of IL-13. Goblet cell hyperplasia was evaluated quantitatively by immunofluorescent staining for MUC5AC, which is a major component of airway mucins. Western blotting was used to assess activation of the signalling molecules, signal transducer and activator of transcription 6 (STAT6), p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2. MUC5AC gene expression was measured by RT-PCR. IL-13 induced mucous cell metaplasia for 7-14 days in mTEC. IL-13 phosphorylated STAT6 within 20 min, whereas it induced delayed phosphorylation of p38 MAPK 36-48 h after stimulation. In contrast, ERK1/2 was constantly activated and was not enhanced by IL-13. An inhibitor of p38 MAPK (SB202190) suppressed mucous cell differentiation in a concentration-dependent manner. In STAT6 knockout mice, IL-13 failed to induce mucous cell metaplasia and activate p38 MAPK. Cycloheximide also diminished activation of p38 MAPK and induction of MUC5AC mRNA expression by IL-13. The p38 MAPK pathway is involved in IL-13-induced mucous cell metaplasia and MUC5AC mRNA regulation in mTEC. In addition, p38 MAPK phosphorylation may require STAT6-dependent de novo protein synthesis induced by IL-13.

EDITORIAL

We start this issue with the first of a set of two ‘Year-in-Review’ papers, highlighting important findings in respiratory medicine from articles published in Respirology in 2007. The first paper by Professor Bardin and Professor Ruffin reviews the clinical science publications in Respirology in 2007. The second ‘Year-in-Review’ paper, which will appear in the next issue, will review the respiratory science publications reported in the Journal in 2007. This issue features the last review in the Presidents' Series by the immediate past-President of the American College of Chest Physicians, Professor Mark Rosen. In his review ‘Pulmonary Complications of HIV Infection’, Professor Rosen discusses the incidence of different pulmonary disorders associated with HIV infection, and their diagnosis and treatment. Professor Rosen is Chief of the Divisions of Pulmonary, Critical Care and Sleep Medicine at North Shore University Hospital and Long Island Jewish Medical Center. His research interests include pulmonary disease and critical care in patients with HIV infection, respiratory failure and medical ethics. He has published extensively on the subject of pulmonary disease in patients with HIV infection and is co-editor of the textbook ‘HIV and the Lung’. I highly recommend this paper to you as it is a comprehensive review of the topic and should be of great interest. We regret to announce the cancellation of the Presidents' Review by Dr Nan Zhong from the APSR owing to unforeseen circumstances. Our next Presidents' Series with reviews by the new Presidents of the major respiratory societies will commence in a later issue this year. Three highlights in this issue are articles studying the role of mitogen-activated protein kinase pathways in airway epithelial cells. The first of these articles ‘Involvement of the p38 MAPK pathway in IL-13-induced mucous cell metaplasia in mouse tracheal epithelial cells’ by Dr Fujisawa et al. (pp. 191–202), demonstrates that the p38 MAPK pathway is involved in IL-13-induced mucous cell metaplasia and MUC5AC mRNA regulation in mouse tracheal epithelial cells and that phosphorylation of p38 MAPK may require STAT6-dependent de novo protein synthesis induced by IL-13. The same study also shows that the ERK1/2 pathway is not directly activated by IL-13. The article ‘Analysis of gene expression in human bronchial epithelial cells upon influenza virus infection and regulation by p38 MAP kinase and JNK’ by Dr Hayashi et al. (pp. 203–214) reports on the role of p38 MAPK in gene expression in human bronchial epithelial cells following influenza virus infection. In ‘Erythromycin attenuates MUC5AC synthesis and secretion in cultured human tracheal cells infected with RV14’ (pp. 215–220), Dr Inoue et al. examine the inhibitory effect of erythromycin on RV14-induced p44/42 MAPK activation and MUC5AC protein production and hypersecretion in human tracheal cells, suggesting a link between the two. Another highlight in this issue is the article by Dr Long et al. entitled ‘Rapid non-genomic effects of glucocorticoids on oxidative stress in a guinea pig model of asthma’ (pp. 227–232). In this study, the authors identify a rapid non-genomic mechanism whereby glucocorticoids reduce oxidative stress in ‘asthmatic’ guinea pigs. These findings may contribute to future developments in the clinical treatment of asthma. The article by Dr Bu et al.‘Effects of independent lung ventilation and lateral position on cytokine markers of inflammation after unilateral lung acid injury in dogs’ (pp. 233–239) compared the effects of different mechanical ventilation settings and lateral body position on inflammatory markers in an animal model of unilateral lung acid injury. Their results suggest that the release of pro-inflammatory cytokines in the injured lung is attenuated by independent lung ventilation and lateral positioning. Early initiation of this type of mechanical ventilation may be of benefit in patients with severe unilateral lung injury. Finally, the Short Communication by Dr Koh et al.‘Vascular endothelial growth factor in epithelial lining fluid of patients with acute respiratory distress syndrome’ (pp. 281–284) demonstrates that elevated levels of vascular endothelial growth factor in lung epithelial lining fluid may predict a better outcome in patients with acute lung injury and acute respiratory distress syndrome. Professor Chong-Kin Liam from the University of Malaya, Malaysia has decided to retire early from his role as Associate Editor of Respirology. Professor Liam joined the Journal in April 2006. His contribution over the past year and a half has been greatly appreciated and we are very grateful for his assistance. Professor Liam will continue to be involved with Respirology as an Editorial Board member. I hope you enjoy this issue of Respirology.

Signaling pathways regulating the airway phenotype of mice exhibiting airway surface dehydration

Overexpression of the epithelial Na+ channel βsubunit (gene Scnn1b) in mouse airways results in airway surface dehydration, neonatal mortality, mucous cell metaplasia and airway inflammation. Crossbreeding Scnn1b‐Tg mice with gene‐deficient mice enables quick and efficient determination of specific pathways relevant to the development of lung pathology. We bred Scnn1b‐Tg mice with mice deficient in: 1) IL‐4 receptor alpha chain (IL‐4Rα), shared by IL‐4 and IL‐13 receptors; 2) TNFα; 3) TNFα receptor 1 (TNFαR1), and evaluated inflammatory infiltrate, cytokine profile, lung pathology, and airway bioelectrics. In Scnn1b‐Tg mice, absence of IL‐4Rα improved neonatal survival and was associated with decreased mucous cells and eosinophilic infiltrate at day 10. However, absence of IL‐4Rα did not affect the chronic inflammatory infiltrate and lung pathology in adult Scnn1b‐Tg mice. Although TNFα was increased in Scnn1b airways, absence of TNFα or TNFαR1 did not ameliorate the lung phenotype of Scnn1b‐Tg mice nor modify airways bioelectrics. To assess the contribution of IL‐1β and TLR pathways, we are currently breeding the Scnn1b‐Tg mice with mice deficient in the adaptor molecule MyD88. These results indicate that multiple pathways contribute to airway inflammation and remodeling in the setting of surface dehydration and mucus stasis.Funded by CFF grants LIVRAG04I0 and RANDEL07P0, and NIH P50 HL060280 to R.C.B

Dipeptidyl Peptidase I-Dependent Neutrophil Recruitment Modulates the Inflammatory Response to Sendai Virus Infection

The role of innate immunity in the pathogenesis of asthma is unclear. Although increased presence of neutrophils is associated with persistent asthma and asthma exacerbations, how neutrophils participate in the pathogenesis of asthma remains controversial. In this study, we show that the absence of dipeptidyl peptidase I (DPPI), a lysosomal cysteine protease found in neutrophils, dampens the acute inflammatory response and the subsequent mucous cell metaplasia that accompanies the asthma phenotype induced by Sendai virus infection. This attenuated phenotype is accompanied by a significant decrease in the accumulation of neutrophils and the local production of CXCL2, TNF, IL-1beta, and IL-6 in the lung of infected DPPI-/- mice. Adoptive transfer of DPPI-sufficient neutrophils into DPPI-/- mice restored the levels of CXCL2 and enhanced cytokine production on day 4 postinfection and subsequent mucous cell metaplasia on day 21 postinfection. These results indicate that DPPI and neutrophils play a critical role in Sendai virus-induced asthma phenotype as a result of a DPPI-dependent neutrophil recruitment and cytokine response.

Anti-Tumor Necrosis Factor-Alpha Treatment Reduces Airway Mucus Cell Metaplasia in a Murine Model of Allergic Asthma

Anti-Tumor Necrosis Factor-Alpha Treatment Reduces Airway Mucus Cell Metaplasia in a Murine Model of Allergic Asthma

Targeted deletion of cannabinoid receptors CB1 and CB2 produced enhanced inflammatory responses to influenza A/PR/8/34 in the absence and presence of Δ9-tetrahydrocannabinol

AbstractWe have previously reported that Δ-9-tetrahydrocannabinol (Δ9-THC)-treated mice challenged with influenza virus A/PR/8/34 (PR8) developed increased viral hemagglutinin 1 (H1) mRNA levels and decreased monocyte and lymphocyte recruitment to the pulmonary airways when compared with mice challenged with PR8 alone. The objective of the present study was to examine the role of cannabinoid (CB1/CB2) receptors in mediating the effects of Δ9-THC on immune and epithelial cell responses to PR8. In the current study, Δ9-THC-treated CB1/CB2 receptor null (CB1−/−/CB2−/−) and wild-type mice infected with PR8 had marked increases in viral H1 mRNA when compared with CB1−/−/CB2−/− and wild-type mice challenged with PR8 alone. However, the magnitude of the H1 mRNA levels was greatly reduced in CB1−/−/CB2−/− mice as compared with wild-type mice. In addition, Δ9-THC-treated CB1−/−/CB2−/− mice infected with PR8 had increased CD4+ T cells and IFN-γ in bronchoalveolar lavage fluid with greater pulmonary inflammation when compared with Δ9-THC-treated wild-type mice infected with PR8. Δ9-THC treatment of CB1−/−/CB2−/− mice in the presence or absence of PR8 challenge also developed greater amounts of mucous cell metaplasia in the affected bronchiolar epithelium. Collectively, the immune and airway epithelial cell responses to PR8 challenge in Δ9-THC-treated CB1−/−/CB2−/− and wild-type mice indicated the involvement of CB1/CB2 receptor-dependent and -independent mechanisms.

A Molecular Signature of Gastric Metaplasia Arising in Response to Acute Parietal Cell Loss

Loss of gastric parietal cells is a critical precursor to gastric metaplasia and neoplasia. However, the origin of metaplasia remains obscure. Acute parietal cell loss in gastrin-deficient mice treated with DMP-777 leads to the rapid emergence of spasmolytic polypeptide/trefoil factor family 2 (TFF2)-expressing metaplasia (SPEM) from the bases of fundic glands. We now sought to characterize more definitively the pathway for emergence of SPEM. Emerging SPEM lineages in gastrin-deficient mice treated with DMP-777 were examined for immunolocalization of TFF2, intrinsic factor, and Mist1, and morphologically with electron microscopy. Emerging SPEM was isolated with laser-capture microdissection and RNA was analyzed using gene microarrays. Immunohistochemistry in mouse and human samples was used to confirm up-regulated transcripts. DMP-777-induced SPEM was immunoreactive for TFF2 and the differentiated chief cell markers, Mist1 and intrinsic factor, suggesting that SPEM derived from transdifferentiation of chief cells. Microarray analysis of microdissected SPEM lineages induced by DMP-777 showed up-regulation of transcripts associated with G1/S cell-cycle transition including minichromosome maintenance deficient proteins, as well as a number of secreted factors, including human epididymis 4 (HE4). HE4, which was absent in the normal stomach, was expressed in SPEM of human and mouse and in intestinal metaplasia and gastric cancer in human beings. Although traditionally metaplasia was thought to originate from normal mucosal progenitor cells, these studies indicate that SPEM evolves through either transdifferentiation of chief cells or activation of a basal cryptic progenitor. In addition, induction of metaplasia elicits the expression of secreted factors, such as HE4, relevant to gastric preneoplasia.

Induction of high-affinity IgE receptor on lung dendritic cells during viral infection leads to mucous cell metaplasia

Induction of high-affinity IgE receptor on lung dendritic cells during viral infection leads to mucous cell metaplasia

γ‐Tocopherol prevents airway eosinophilia and mucous cell hyperplasia in experimentally induced allergic rhinitis and asthma

Traditional therapies for asthma and allergic rhinitis (AR) such as corticosteroids and antihistamines are not without limitations and side effects. The use of complementary and alternative approaches to treat allergic airways disease, including the use of herbal and dietary supplements, is increasing but their efficacy and safety are relatively understudied. Previously, we have demonstrated that gamma-tocopherol (gammaT), the primary form of dietary vitamin E, is more effective than alpha-tocopherol, the primary form found in supplements and tissue, in reducing systemic inflammation induced by non-immunogenic stimuli. We used allergic Brown Norway rats to test the hypothesis that a dietary supplement with gammaT would protect from adverse nasal and pulmonary responses to airway allergen provocation. Ovalbumin (OVA)-sensitized Brown Norway rats were treated orally with gammaT before intranasal provocation with OVA. Twenty-four hours after two challenges, histopathological changes in the nose, sinus and pulmonary airways were compared with gene expression and cytokine production in bronchoalveolar lavage fluid and plasma. We found that acute dosing for 4 days with gammaT was sufficient to provide broad protection from inflammatory cell recruitment and epithelial cell alterations induced by allergen challenge. Eosinophil infiltration into airspaces and tissues of the lung, nose, sinus and nasolacrimal duct was blocked in allergic rats treated with gammaT. Pulmonary production of soluble mediators PGE(2), LTB(4) and cysteinyl leukotrienes, and nasal expression of IL-4, -5, -13 and IFN-gamma were also inhibited by gammaT. Mucous cell metaplasia, the increase in the number of goblet cells and amounts of intraepithelial mucus storage, was induced by allergen in both pulmonary and nasal airways and decreased by treatment with gammaT. Acute treatment with gammaT inhibits important inflammatory pathways that underlie the pathogenesis of both AR and asthma. Supplementation with gammaT may be a novel complementary therapy for allergic airways disease.