Towards an artificial human lung: modelling organ-like complexity to aid mechanistic understanding.

Respiratory diseases account for over 5 million deaths yearly and are a huge burden to healthcare systems worldwide. Murine models have been of paramount importance to decode human lung biology in vivo, but their genetic, anatomical, physiological and immunological differences with humans significantly hamper successful translation of research into clinical practice. Thus, to clearly understand human lung physiology, development, homeostasis and mechanistic dysregulation that may lead to disease, it is essential to develop models that accurately recreate the extraordinary complexity of the human pulmonary architecture and biology. Recent advances in micro-engineering technology and tissue engineering have allowed the development of more sophisticated models intending to bridge the gap between the native lung and its replicates in vitro Alongside advanced culture techniques, remarkable technological growth in downstream analyses has significantly increased the predictive power of human biology-based in vitro models by allowing capture and quantification of complex signals. Refined integrated multi-omics readouts could lead to an acceleration of the translational pipeline from in vitro experimental settings to drug development and clinical testing in the future. This review highlights the range and complexity of state-of-the-art lung models for different areas of the respiratory system, from nasal to large airways, small airways and alveoli, with consideration of various aspects of disease states and their potential applications, including pre-clinical drug testing. We explore how development of optimised physiologically relevant in vitro human lung models could accelerate the identification of novel therapeutics with increased potential to translate successfully from the bench to the patient's bedside.

Clinical evaluation of type 2 disease status in a real-world population of difficult to manage asthma using historic electronic healthcare records of blood eosinophil counts.

BACKGROUND: Blood eosinophil measurement is essential for the phenotypic characterization of patients with difficult asthma and in determining eligibility for anti-IL-5/IL-5Rα biological therapies. However, assessing such measures over limited time spans may not reveal the true underlying eosinophilic phenotype, as treatment, including daily oral corticosteroid therapy, suppresses eosinophilic inflammation and asthma is intrinsically variable. METHODS: We interrogated the electronic healthcare records of patients in the Wessex AsThma CoHort of difficult asthma (WATCH) study (UK). In 501 patients being evaluated in this tertiary care centre for difficult to control asthma, all requested full blood count test results in a 10-year retrospective period from the index WATCH assessment were investigated (n = 11,176). RESULTS: In 235 biological therapy-naïve participants who had 10 or more measures in this time period, 40.3% were eosinophilic (blood eosinophils ≥300 cells/µl) at WATCH enrolment whilst an additional 43.1%, though not eosinophilic at enrolment, demonstrated eosinophilia at least once in the preceding decade. Persistent eosinophilia was associated with worse post-bronchodilator airway obstruction and higher Fractional exhaled Nitric Oxide (FeNO). In contrast, the 16.6% of patients who never demonstrated eosinophilia at this blood eosinophil threshold showed preserved lung function and lower markers of Type 2 inflammation. CONCLUSIONS: This highlights the central role that type 2 inflammation, as indicated by blood eosinophilia, has in difficult asthma and suggests that longitudinal electronic healthcare record analysis can be an important tool in clinical asthma phenotyping, providing insight that may help understand disease progression and better guide more specific treatment approaches.

Involvement of the epidermal growth factor receptor in IL-13-mediated corticosteroid-resistant airway inflammation.

BACKGROUND: Effective treatment for severe asthma is a significant unmet need. While eosinophilic inflammation caused by type 2 cytokines is responsive to corticosteroid and biologic therapies, many severe asthmatics exhibit corticosteroid-unresponsive mixed granulocytic inflammation. OBJECTIVE: Here, we tested the hypothesis that the pro-allergic cytokine, IL-13, can drive both corticosteroid-sensitive and corticosteroid-resistant responses. RESULTS: By integration of in vivo and in vitro models of IL-13-driven inflammation, we identify a role for the epidermal growth factor receptor (EGFR/ERBB1) as a mediator of corticosteroid-unresponsive inflammation and bronchial hyperresponsiveness driven by IL-13. Topological data analysis using human epithelial transcriptomic data from the U-BIOPRED cohort identified severe asthma groups with features consistent with the presence of IL-13 and EGFR/ERBB activation, with involvement of distinct EGFR ligands. Our data suggest that IL-13 may play a dual role in severe asthma: on the one hand driving pathologic corticosteroid-refractory mixed granulocytic inflammation, but on the other hand underpinning beneficial epithelial repair responses, which may confound responses in clinical trials. CONCLUSION AND CLINICAL RELEVANCE: Detailed dissection of those molecular pathways that are downstream of IL-13 and utilize the ERBB receptor and ligand family to drive corticosteroid-refractory inflammation should enhance the development of new treatments that target this sub-phenotype(s) of severe asthma, where there is an unmet need.

Protocol for the Wessex AsThma CoHort of difficult asthma (WATCH): a pragmatic real-life longitudinal study of difficult asthma in the clinic.

BACKGROUND: Asthma is now widely recognised to be a heterogeneous disease. The last two decades have seen the identification of a number of biological targets and development of various novel therapies. Despite this, asthma still represents a significant health and economic burden worldwide. Why some individuals should continue to suffer remains unclear. METHODS: The Wessex Asthma Cohort of Difficult Asthma (WATCH) is an ongoing 'real-life', prospective study of patients in the University Hospital Southampton Foundation Trust (UHSFT) Difficult Asthma service. Research data capture is aligned with the extensive clinical characterisation required of a commissioned National Health Service (NHS) Specialist Centre for Severe Asthma. Data acquisition includes detailed clinical, health and disease-related questionnaires, anthropometry, allergy and lung function testing, radiological imaging (in a small subset) and collection of biological samples (blood, urine and sputum). Prospective data are captured in parallel to clinical follow up appointments, with data entered into a bespoke database. DISCUSSION: The pragmatic ongoing nature of the WATCH study allows comprehensive assessment of the real world clinical spectrum seen in a Specialist Asthma Centre and allows a longitudinal perspective of deeply phenotyped patients. It is anticipated that the WATCH cohort would act as a vehicle for potential collaborative asthma studies and will build upon our understanding of mechanisms underlying difficult asthma.

Sox17 is required for normal pulmonary vascular morphogenesis.

The SRY-box containing transcription factor Sox17 is required for endoderm formation and vascular morphogenesis during embryonic development. In the lung, Sox17 is expressed in mesenchymal progenitors of the embryonic pulmonary vasculature and is restricted to vascular endothelial cells in the mature lung. Conditional deletion of Sox17 in splanchnic mesenchyme-derivatives using Dermo1-Cre resulted in substantial loss of Sox17 from developing pulmonary vascular endothelial cells and caused pulmonary vascular abnormalities before birth, including pulmonary vein varices, enlarged arteries, and decreased perfusion of the microvasculature. While survival of Dermo1-Cre;Sox17Δ/Δ mice (herein termed Sox17Δ/Δ) was unaffected at E18.5, most Sox17Δ/Δ mice died by 3 weeks of age. After birth, the density of the pulmonary microvasculature was decreased in association with alveolar simplification, biventricular cardiac hypertrophy, and valvular regurgitation. The severity of the postnatal cardiac phenotype was correlated with the severity of pulmonary vasculature abnormalities. Sox17 is required for normal formation of the pulmonary vasculature and postnatal cardiovascular homeostasis.

Compartment-specific expression of collagens and their processing enzymes in intrapulmonary arteries of IPAH patients.

Alterations in extracellular matrix (ECM) have been implicated in the pathophysiology of pulmonary hypertension. Here, we have undertaken a compartment-specific study to elucidate the expression profile of collagens and their processing enzymes in donor and idiopathic pulmonary arterial hypertension (IPAH) pulmonary arteries. Predominant intimal, but also medial and perivascular, remodeling and reduced lumen diameter were detected in IPAH pulmonary arteries. Two-photon microscopy demonstrated accumulation of collagen fibers. Quantification of collagen in pulmonary arteries revealed collagen accumulation mainly in the intima of IPAH pulmonary arteries compared with donors. Laser capture-microdissected pulmonary artery profiles (intima+media and perivascular tissue) were analyzed by real-time PCR for ECM gene expression. In the intima+media of IPAH vessels, collagens (COL4A5, COL14A1, and COL18A1), matrix metalloproteinase (MMP) 19, and a disintegrin and metalloprotease (ADAM) 33 were higher expressed, whereas MMP10, ADAM17, TIMP1, and TIMP3 were less abundant. Localization of COLXVIII, its cleavage product endostatin, and MMP10, ADAM33, and TIMP1 was confirmed in pulmonary arteries by immunohistochemistry. ELISA for collagen XVIII/endostatin demonstrated significantly elevated plasma levels in IPAH patients compared with donors, whereas circulating MMP10, ADAM33, and TIMP1 levels were similar between the two groups. Endostatin levels were correlated with pulmonary arterial wedge pressure, and established prognostic markers of IPAH, right atrial pressure, cardiac index, 6-min walking distance, NH2-terminal pro-brain natriuretic peptide, and uric acid. Expression of unstudied collagens, MMPs, ADAMs, and TIMPs were found to be significantly altered in IPAH intima+media. Elevated levels of circulating collagen XVIII/endostatin are associated with markers of a poor prognosis.

Foxa3 induces goblet cell metaplasia and inhibits innate antiviral immunity.

RATIONALE: Goblet cell metaplasia accompanies common pulmonary disorders that are prone to recurrent viral infections. Mechanisms regulating both goblet cell metaplasia and susceptibility to viral infection associated with chronic lung diseases are incompletely understood. OBJECTIVES: We sought to identify the role of the transcription factor FOXA3 in regulation of goblet cell metaplasia and pulmonary innate immunity. METHODS: FOXA3 was identified in airways from patients with asthma and chronic obstructive pulmonary disease. We produced transgenic mice conditionally expressing Foxa3 in airway epithelial cells and developed human bronchial epithelial cells expressing Foxa3. Foxa3-regulated genes were identified by immunostaining, Western blotting, and RNA analysis. Direct binding of FOXA3 to target genes was identified by chromatin immunoprecipitation sequencing correlated with RNA sequencing. MEASUREMENTS AND MAIN RESULTS: FOXA3 was highly expressed in airway goblet cells from patients with asthma and chronic obstructive pulmonary disease. FOXA3 was induced by either IL-13 or rhinovirus. Foxa3 induced goblet cell metaplasia and enhanced expression of a network of genes mediating mucus production. Paradoxically, FOXA3 inhibited rhinovirus-induced IFN production, IRF-3 phosphorylation, and IKKε expression and inhibited viral clearance and expression of genes required for antiviral defenses, including MDA5, RIG-I, TLR3, IRF7/9, and nuclear factor-κB. CONCLUSIONS: FOXA3 induces goblet cell metaplasia in response to infection or Th2 stimulation. Suppression of IFN signaling by FOXA3 provides a plausible mechanism that may serve to limit ongoing Th1 inflammation during the resolution of acute viral infection; however, inhibition of innate immunity by FOXA3 may contribute to susceptibility to viral infections associated with chronic lung disorders accompanied by chronic goblet cell metaplasia.

SAM-pointed domain ETS factor mediates epithelial cell-intrinsic innate immune signaling during airway mucous metaplasia.

Airway mucus plays a critical role in clearing inhaled toxins, particles, and pathogens. Diverse toxic, inflammatory, and infectious insults induce airway mucus secretion and goblet cell metaplasia to preserve airway sterility and homeostasis. However, goblet cell metaplasia, mucus hypersecretion, and airway obstruction are integral features of inflammatory lung diseases, including asthma, chronic obstructive lung disease, and cystic fibrosis, which cause an immense burden of morbidity and mortality. These chronic lung diseases are united by susceptibility to microbial colonization and recurrent airway infections. Whether these twinned phenomena (mucous metaplasia, compromised host defenses) are causally related has been unclear. Here, we demonstrate that SAM pointed domain ETS factor (SPDEF) was induced by rhinoviral infection of primary human airway cells and that cytoplasmic activities of SPDEF, a transcriptional regulator of airway goblet cell metaplasia, inhibited Toll-like receptor (TLR) activation of epithelial cells. SPDEF bound to and inhibited activities of TLR signaling adapters, MyD88 and TRIF, inhibiting MyD88-induced cytokine production and TRIF-induced interferon ß production. Conditional expression of SPDEF in airway epithelial cells in vivo inhibited LPS-induced neutrophilic infiltration and bacterial clearance. SPDEF-mediated inhibition of both TLR and type I interferon signaling likely protects the lung against inflammatory damage when inciting stimuli are not eradicated. Present findings provide, at least in part, a molecular explanation for increased susceptibility to infection in lung diseases associated with mucous metaplasia and a mechanism by which patients with florid mucous metaplasia may tolerate microbial burdens that are usually associated with fulminant inflammatory disease in normal hosts.

Associations of Breathing Pattern Disorder and Nijmegen Score With Clinical Outcomes in Difficult-to-Treat Asthma.

BACKGROUND: Breathing pattern disorder (BPD) reflects altered biomechanical patterns of breathing that drive breathing difficulty and commonly accompanies difficult-to-treat asthma. Diagnosis of BPD has no gold standard, but Nijmegen Questionnaire (NQ) >23 is commonly used. OBJECTIVES: We sought to advance clinical characterization of BPD and better understand the clinical utility of NQ in difficult asthma in patients from the Wessex AsThma CoHort of difficult asthma (WATCH) study. METHODS: Associations between demographic and clinical factors in difficult asthma and BPD, ascertained by clinical diagnosis (yes/no, n = 476), by NQ scores (≤23: normal [no suggestion of BPD] and >23: abnormal [suggested BPD], n = 372), as well as the continuous raw NQ scores were assessed in univariate models to identify significant risk factors associated with the 3 BPD outcomes. For the clinician-diagnosed and NQ-based BPD, associations of continuous factors were assessed using the independent samples t test or the Mann-Whitney U test as appropriate for the data distribution or by the Spearman correlation test. Dichotomous associations were evaluated using χ2 tests. Multivariable logistic (dichotomous outcomes) and linear regression models (continuous outcomes) were developed to identify predictive factors associated with clinician-diagnosed and NQ-based BPD, dichotomous and continuous. Patients with data on NQ scores were grouped into NQ quartiles (low, moderate, high, and very high). The patterns of association of the quartiles with 4 health-related questionnaire outcomes were assessed using linear regression analyses. RESULTS: Multivariable regression identified that clinically diagnosed BPD was associated with female sex (odds ratio [OR]: 1.85; 95% confidence interval [CI]: 1.07, 3.20), comorbidities (rhinitis [OR: 2.46; 95% CI: 1.45, 4.17], gastroesophageal reflux disease [GORD] [OR: 2.77; 95% CI: 1.58, 4.84], inducible laryngeal obstruction [OR: 4.37; 95% CI: 2.01, 9.50], and any psychological comorbidity [OR: 1.86; 95% CI: 1.13, 3.07]), and health care usage (exacerbations [OR: 1.07; 95% CI: 1.003, 1.14] and previous intensive care unit (ICU) admissions [OR: 2.03; 95% CI: 1.18, 3.47]). Abnormal NQ-based BPD diagnosis was associated with history of eczema (OR: 1.83; 95% CI: 1.07, 3.14), GORD (OR: 1.94; 95% CI: 1.15, 3.27), or any psychological comorbidity (OR: 4.29; 95% CI: 2.64, 6.95) at multivariable regression. Differences between clinical and NQ-based BPD traits were also found with 42% discordance in BPD state between these definitions. Multivariable linear regression analysis with NQ as a continuous outcome showed positive association with worse asthma outcomes (admission to ICU, P = .037), different phenotypic traits (female sex, P = .001; ever smoker, P = .025), and greater multimorbidity (GORD, P = .002; sleep apnea, P = .04; and any psychological comorbidity, P < .0001). CONCLUSION: BPD is associated with worse health outcomes and negative health impacts in difficult asthma within a multimorbidity disease model. It therefore merits better recognition and prompt treatment. Clinical diagnosis and NQ offer different perspectives on BPD, so this goal may be best addressed by considering clinical features alongside the magnitude of NQ.

Comprehensive Characterization of Difficult-to-Treat Asthma Reveals Near Absence of T2-Low Status.

BACKGROUND: Asthma is conventionally stratified as type 2 inflammation (T2)-high or T2-low disease. Identifying T2 status has therapeutic implications for patient management, but a real-world understanding of this T2 paradigm in difficult-to-treat and severe asthma remains limited. OBJECTIVES: To identify the prevalence of T2-high status in difficult-to-treat asthma patients using a multicomponent definition and compare clinical and pathophysiologic characteristics between patients classified as T2-high and T2-low. METHODS: We evaluated 388 biologic-naive patients from the Wessex Asthma Cohort of difficult asthma (WATCH) study in the United Kingdom. Type 2-high asthma was defined as 20 parts per billion or greater FeNO , 150 cells/µL or greater peripheral blood eosinophils, the need for maintenance oral corticosteroids, and/or clinically allergy-driven asthma. RESULTS: This multicomponent assessment identified T2-high asthma in 93% of patients (360 of 388). Body mass index, inhaled corticosteroid dose, asthma exacerbations, and common comorbidities did not differ by T2 status. Significantly worse airflow limitation was found in T2-high compared with T2-low patients (FEV1/FVC 65.9% vs 74.6%). Moreover, 75% of patients defined as having T2-low asthma had raised peripheral blood eosinophils within the preceding 10 years, which left only seven patients (1.8%) who had never had T2 signals. Incorporation of sputum eosinophilia 2% or greater into the multicomponent definition in a subset of 117 patients with induced sputum data similarly found that 96% (112 of 117) met criteria for T2-high asthma, 50% of whom (56 of 112) had sputum eosinophils 2% or greater. CONCLUSIONS: Almost all patients with difficult-to-treat asthma have T2-high disease; less than 2% of patients never display T2-defining criteria. This highlights a need to assess T2 status comprehensively in clinical practice before labeling a patient with difficult-to-treat asthma as T2-low.

How Does Mild Asthma Differ Phenotypically from Difficult-to-Treat Asthma?

Background: Despite most of the asthma population having mild disease, the mild asthma phenotype is poorly understood. Here, we aim to address this gap in knowledge by extensively characterising the mild asthma phenotype and comparing this with difficult-to-treat asthma. Methods: We assessed two real-world adult cohorts from the South of England using an identical methodology: the Wessex AsThma CoHort of difficult asthma (WATCH) (n=498) and a mild asthma cohort from the comparator arm of the Epigenetics Of Severe Asthma (EOSA) study (n=67). Data acquisition included detailed clinical, health and disease-related questionnaires, anthropometry, allergy and lung function testing, plus biological samples (blood and sputum) in a subset. Results: Mild asthma is predominantly early-onset and is associated with type-2 (T2) inflammation (atopy, raised fractional exhaled nitric oxide (FeNO), blood/sputum eosinophilia) plus preserved lung function. A high prevalence of comorbidities and multimorbidity was observed in mild asthma, particularly depression (58.2%) and anxiety (56.7%). In comparison to difficult asthma, mild disease showed similar female predominance (>60%), T2-high inflammation and atopy prevalence, but lower peripheral blood/airway neutrophil counts and preserved lung function. Mild asthma was also associated with a greater prevalence of current smokers (20.9%). A multi-component T2-high inflammatory measure was comparable between the cohorts; T2-high status 88.1% in mild asthma and 93.5% in difficult asthma. Conclusion: Phenotypic characterisation of mild asthma identified early-onset disease with high prevalence of current smokers, T2-high inflammation and significant multimorbidity burden. Early comprehensive assessment of mild asthma patients could help prevent potential later progression to more complex severe disease.

COVID-19 vaccination acceptance, safety and side-effects in European patients with severe asthma.

Background: Vaccination is vital for achieving population immunity to severe acute respiratory syndrome coronavirus 2, but vaccination hesitancy presents a threat to achieving widespread immunity. Vaccine acceptance in chronic potentially immunosuppressed patients is largely unclear, especially in patients with asthma. The aim of this study was to investigate the vaccination experience in people with severe asthma. Methods: Questionnaires about vaccination beliefs (including the Vaccination Attitudes Examination (VAX) scale, a measure of vaccination hesitancy-related beliefs), vaccination side-effects, asthma control and overall safety perceptions following coronavirus disease 2019 (COVID-19) vaccination were sent to patients with severe asthma in 12 European countries between May and June 2021. Results: 660 participants returned completed questionnaires (87.4% response rate). Of these, 88% stated that they had been, or intended to be, vaccinated, 9.5% were undecided/hesitant and 3% had refused vaccination. Patients who hesitated or refused vaccination had more negative beliefs towards vaccination. Most patients reported mild (48.2%) or no side-effects (43.8%). Patients reporting severe side-effects (5.7%) had more negative beliefs. Most patients (88.8%) reported no change in asthma symptoms after vaccination, while 2.4% reported an improvement, 5.3% a slight deterioration and 1.2% a considerable deterioration. Almost all vaccinated (98%) patients would recommend vaccination to other severe asthma patients. Conclusions: Uptake of vaccination in patients with severe asthma in Europe was high, with a small minority refusing vaccination. Beliefs predicted vaccination behaviour and side-effects. Vaccination had little impact on asthma control. Our findings in people with severe asthma support the broad message that COVID-19 vaccination is safe and well tolerated.

Regulation of a disintegrin and metalloprotease-33 expression by transforming growth factor-ß.

The asthma susceptibility gene, a disintegrin and metalloprotease-33 (ADAM33), is selectively expressed in mesenchymal cells, and the activity of soluble ADAM33 has been linked to angiogenesis and airway remodeling. Transforming growth factor (TGF)-ß is a profibrogenic growth factor, the expression of which is increased in asthma, and recent studies show that it enhances shedding of soluble ADAM33. In this study, we hypothesized that TGF-ß also affects ADAM33 expression in bronchial fibroblasts in asthma. Primary fibroblasts were grown from bronchial biopsies from donors with and those without asthma, and treated with TGF-ß(2) to induce myofibroblast differentiation. ADAM33 expression was assessed using quantitative RT-PCR and Western blotting. To examine the mechanisms whereby TGF-ß(2) affected ADAM33 expression, quantitative methylation-sensitive PCR, chromatin immunoprecipitation, and nuclear accessibility assays were conducted on the ADAM33 promoter. We found that TGF-ß(2) caused a time- and concentration-dependent reduction in ADAM33 mRNA expression in normal and asthmatic fibroblasts, affecting levels of splice variants similarly. TGF-ß(2) also induced ADAM33 protein turnover and appearance of a cell-associated C-terminal fragment. TGF-ß(2) down-regulated ADAM33 mRNA expression by causing chromatin condensation around the ADAM33 promoter with deacetylation of histone H3, demethylation of H3 on lysine-4, and hypermethylation of H3 on lysine-9. However, the methylation status of the ADAM33 promoter did not change. Together, these data suggest that TGF-ß(2) suppresses expression of ADAM33 mRNA in normal or asthmatic fibroblasts. This occurs by altering chromatin structure, rather than by gene silencing through DNA methylation as in epithelial cells. This may provide a mechanism for fine regulation of levels of ADAM33 expression in fibroblasts, and may self-limit TGF-ß(2)-induced ectodomain shedding of ADAM33.

Spiruchostatin A inhibits proliferation and differentiation of fibroblasts from patients with pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disorder characterized by the proliferation of interstitial fibroblasts and the deposition of extracellular matrix causing impaired gas exchange. Spiruchostatin A (SpA) is a histone deacetylase inhibitor (HDI) with selectivity toward Class I enzymes, which distinguishes it from other nonspecific HDIs that are reported to inhibit (myo)fibroblast proliferation and differentiation. Because the selectivity of HDIs may be important clinically, we postulated that SpA inhibits the proliferation and differentiation of IPF fibroblasts. Primary fibroblasts were grown from lung biopsy explants obtained from patients with IPF or from normal control subjects, using two-dimensional or three-dimensional culture models. The effect of SpA on fibroproliferation in serum-containing medium ± transforming growth factor (TGF)-ß(1) was quantified by methylene blue binding. The acetylation of histone H3, the expression of the cell-cycle inhibitor p21(waf1), and the myofibroblast markers α-smooth muscle actin (α-SMA) and collagens I and III were determined by Western blotting, quantitative RT-PCR, immunofluorescent staining, or colorimetry. SpA inhibited the proliferation of IPF or normal fibroblasts in a time-dependent and concentration-dependent manner (concentration required to achieve 50% inhibition = 3.8 ± 0.4 nM versus 7.8 ± 0.2 nM, respectively; P < 0.05), with little cytotoxicity. Western blot analyses revealed that SpA caused a concentration-dependent increase in histone H3 acetylation, paralleling its antiproliferative effect. SpA also increased p21(waf1) expression, suggesting that direct cell-cycle regulation was the mechanism of inhibiting proliferation. Although treatment with TGF-ß(1) induced myofibroblast differentiation associated with increased expression of α-SMA, collagen I and collagen III and soluble collagen release, these responses were potently inhibited by SpA. These data support the concept that bicyclic tetrapeptide HDIs merit further investigation as potential treatments for IPF.

Kruppel-like factor 5 is required for formation and differentiation of the bladder urothelium.

Kruppel-like transcription factor 5 (Klf5) was detected in the developing and mature murine bladder urothelium. Herein we report a critical role of KLF5 in the formation and terminal differentiation of the urothelium. The Shh(GfpCre) transgene was used to delete the Klf5(floxed) alleles from bladder epithelial cells causing prenatal hydronephrosis, hydroureter, and vesicoureteric reflux. The bladder urothelium failed to stratify and did not express terminal differentiation markers characteristic of basal, intermediate, and umbrella cells including keratins 20, 14, and 5, and the uroplakins. The effects of Klf5 deletion were unique to the developing bladder epithelium since maturation of the epithelium comprising the bladder neck and urethra was unaffected by the lack of KLF5. mRNA analysis identified reductions in Pparγ, Grhl3, Elf3, and Ovol1expression in Klf5 deficient fetal bladders supporting their participation in a transcriptional network regulating bladder urothelial differentiation. KLF5 regulated expression of the mGrhl3 promoter in transient transfection assays. The absence of urothelial Klf5 altered epithelial-mesenchymal signaling leading to the formation of an ectopic alpha smooth muscle actin positive layer of cells subjacent to the epithelium and a thinner detrusor muscle that was not attributable to disruption of SHH signaling, a known mediator of detrusor morphogenesis. Deletion of Klf5 from the developing bladder urothelium blocked epithelial cell differentiation, impaired bladder morphogenesis and function causing hydroureter and hydronephrosis at birth.

A disintegrin and metalloprotease (ADAM) 33 protein in patients with pulmonary sarcoidosis.

BACKGROUND AND OBJECTIVE: A disintegrin and metalloproteinase (ADAM) 33 is a susceptibility gene associated with inflammatory lung and skin diseases. It is selectively expressed in mesenchymal cells, and its metalloprotease activity has been linked to angiogenesis and tissue remodelling. A soluble form of ADAM33 (sADAM33) has been identified in the bronchoalveolar lavage fluid (BALF) of asthmatic patients, and its levels inversely correlate with lung function. Because of its association with inflammatory lung diseases, it was hypothesized that sADAM33 is elevated in BALF of patients with pulmonary sarcoidosis. METHODS: After removal of Ig using Protein A/G and enrichment using Concanavalin A beads, sADAM33 was identified in BALF by Western blotting. A fluorescence resonance energy transfer peptide cleavage assay was used to assess ADAM33-like activity in BALF. RESULTS: sADAM33 protein in BALF was detected as a 25 kDa fragment, and levels were significantly increased in samples from sarcoid patients when compared to healthy controls (P < 0.05). Levels of sADAM33 were inversely correlated with lung function (FVC%) (P < 0.05) and DL(CO) % predicted (P < 0.01). No difference in sADAM33 enzymatic activity was observed between healthy and sarcoid BALF samples. CONCLUSIONS: Release of sADAM33 is increased in sarcoid and may be associated with abnormal lung function. sADAM33 may be a biomarker of lung tissue inflammation and remodelling in sarcoid.

Resistin-like molecule-ß is induced following bronchoconstriction of asthmatic airways.

BACKGROUND AND OBJECTIVE: Resistin-like molecule-ß (RELM-ß) is a necessary and sufficient stimulus for airway remodelling in animal models of asthma, but until recently, its role in human disease had not been investigated. The hypothesis that RELM-ß expression would increase with increasing asthma severity and further increase following acute bronchoconstrictor challenges has been examined. METHODS: Bronchial biopsies from healthy subjects and patients with mild and severe asthma were immunostained for RELM-ß, as were airway biopsies obtained in mild asthmatics before and 4 days after repeated inhalation challenges with either allergen, methacholine or methacholine preceded by salbutamol as a control. Bronchial brushings were also evaluated for RELM-ß mRNA. RESULTS: RELM-ß immunoreactivity, which co-localized to airway epithelial cells, increased with disease severity; healthy volunteers, median per cent epithelial area 1.98%, mild asthma 3.49% and severe asthma 5.89% (P < 0.001 between groups). RELM-ß immunoreactivity significantly and inversely correlated in asthma with forced expiratory volume in 1 s % predicted (P = 0.005). Acute changes in immunoexpression were evident after repeated inhalation challenge with allergen (2.15 % to 4.35 % (P = 0.01)) and methacholine (4.21 % to 6.16 % (P = 0.01)) but did not change in the salbutamol/methacholine challenge group. These changes correlated with change in basement membrane thickness (r = 0.38, P = 0.02). Epithelial RELM-ß gene expression was not altered in asthma. CONCLUSIONS: RELM-ß may play an important role not only in animal models of airway remodelling, but also in human airway pathology.