Pulmonary-intestinal cross-talk in mucosal inflammatory disease

Importance of mast cell Prss31/transmembrane tryptase/tryptase-γ in lung function and experimental chronic obstructive pulmonary disease and colitis

Protease serine member S31 (Prss31)/transmembrane tryptase/tryptase-γ is a mast cell (MC)-restricted protease of unknown function that is retained on the outer leaflet of the plasma membrane when MCs are activated. We determined the nucleotide sequences of the Prss31 gene in different mouse strains and then used a Cre/loxP homologous recombination approach to create a novel Prss31(-/-) C57BL/6 mouse line. The resulting animals exhibited no obvious developmental abnormality, contained normal numbers of granulated MCs in their tissues, and did not compensate for their loss of the membrane tryptase by increasing their expression of other granule proteases. When Prss31-null MCs were activated with a calcium ionophore or by their high affinity IgE receptors, they degranulated in a pattern similar to that of WT MCs. Prss31-null mice had increased baseline airway reactivity to methacholine but markedly reduced experimental chronic obstructive pulmonary disease and colitis, thereby indicating both beneficial and adverse functional roles for the tryptase. In a cigarette smoke-induced model of chronic obstructive pulmonary disease, WT mice had more pulmonary macrophages, higher histopathology scores, and more fibrosis in their small airways than similarly treated Prss31-null mice. In a dextran sodium sulfate-induced acute colitis model, WT mice lost more weight, had higher histopathology scores, and contained more Cxcl-2 and IL-6 mRNA in their colons than similarly treated Prss31-null mice. The accumulated data raise the possibility that inhibitors of this membrane tryptase may provide additional therapeutic benefit in the treatment of humans with these MC-dependent inflammatory diseases.

Animal models of chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a leading global cause of mortality and chronic morbidity. Inhalation of cigarette smoke is the principal risk factor for development of this disease. COPD is a progressive disease that is typically characterised by chronic pulmonary inflammation, mucus hypersecretion, airway remodelling and emphysema that collectively reduce lung function. There are currently no therapies that effectively halt or reverse disease progression. It is hoped that the development of animal models that develop the hallmark features of COPD, in a short time frame, will aid in the identifying and testing of new therapeutic approaches.

AREAS COVERED

The authors review the recent developments in mouse models of chronic cigarette smoke-induced COPD as well as the principal findings. Furthermore, the authors discuss the use of mouse models to understand the pathogenesis and the contribution of infectious exacerbations. They also discuss the investigations of the systemic co-morbidities of COPD (pulmonary hypertension, cachexia and osteoporosis).

EXPERT OPINION

Recent advances in the field mark a point where animal models recapitulate the pathologies of COPD patients in a short time frame. They also reveal novel insights into the pathogenesis and potential treatment of this debilitating disease.

Disturbed intestinal integrity in patients with COPD: effects of activities of daily living

BACKGROUND

COPD is accepted to be a multicomponent disease with various comorbidities. To our knowledge, the contribution of the GI tract to the systemic manifestation of COPD has never been investigated. This metabolically active organ may experience recurring local oxygen deficits during daily life, leading to disturbed intestinal integrity in patients with COPD.

METHODS

Eighteen patients with moderate COPD (mean FEV₁, 55 ± 3% predicted) and 14 matched healthy control subjects were tested on two occasions: a baseline measurement at rest and, on another day, during the performance of activities of daily living (ADLs). To assess enterocyte damage, plasma intestinal fatty acid binding protein (IFABP) levels were determined, whereas urinary excretion of orally ingested sugar probes was measured using liquid chromatography and mass spectrometry to assess GI permeability.

RESULTS

Plasma IFABP concentrations were not different between patients with COPD and healthy control subjects at rest. In contrast, 0- to 3-h urinary lactulose to rhamnose and sucralose to erythritol ratios and 5- to 24-h urinary sucralose to erythritol ratios were significantly higher in patients with COPD compared with control subjects, indicating increased permeability of the small intestine and colon. Furthermore, the performance of ADLs led to significantly increased plasma IFABP concentrations in patients with COPD but not in control subjects. Similarly, the intestinal permeability difference between patients and control subjects was intensified.

CONCLUSIONS

Besides an altered intestinal permeability in patients with COPD when at rest, performing ADLs led to enterocyte damage in addition to intestinal hyperpermeability in patients with COPD but not in control subjects, indicating functional alteration in the GI tract. Hence, intestinal compromise should be considered as a new component of the multisystem disorder COPD.

TRIAL REGISTRY

ISRCTN Register; No.: ISRCTN33686980; URL: www.controlled-trials.com.

Neonatal Fc receptor expression in dendritic cells mediates protective immunity against colorectal cancer

Cancers arising in mucosal tissues account for a disproportionately large fraction of malignancies. Immunoglobulin G (IgG) and the neonatal Fc receptor for IgG (FcRn) have an important function in the mucosal immune system that we have now shown extends to the induction of CD8(+) T cell-mediated antitumor immunity. We demonstrate that FcRn within dendritic cells (DCs) was critical for homeostatic activation of mucosal CD8(+) T cells that drove protection against the development of colorectal cancers and lung metastases. FcRn-mediated tumor protection was driven by DCs activation of endogenous tumor-reactive CD8(+) T cells via the cross-presentation of IgG complexed antigens (IgG IC), as well as the induction of cytotoxicity-promoting cytokine secretion, particularly interleukin-12, both of which were independently triggered by the FcRn-IgG IC interaction in murine and human DCs. FcRn thus has a primary role within mucosal tissues in activating local immune responses that are critical for priming efficient anti-tumor immunosurveillance.

Gut-lung crosstalk in pulmonary involvement with inflammatory bowel diseases

Pulmonary abnormalities, dysfunction or hyper-reactivity occurs in association with inflammatory bowel disease (IBD) more frequently than previously recognized. Emerging evidence suggests that subtle inflammation exists in the airways among IBD patients even in the absence of any bronchopulmonary symptoms, and with normal pulmonary functions. The pulmonary impairment is more pronounced in IBD patients with active disease than in those in remission. A growing number of case reports show that the IBD patients develop rapidly progressive respiratory symptoms after colectomy, with failure to isolate bacterial pathogens on repeated sputum culture, and often request oral corticosteroid therapy. All the above evidence indicates that the inflammatory changes in both the intestine and lung during IBD. Clinical or subclinical pulmonary inflammation accompanies the main inflammation of the bowel. Although there are clinical and epidemiological reports of chronic inflammation of the pulmonary and intestinal mucosa in IBD, the detailed mechanisms of pulmonary-intestinal crosstalk remain unknown. The lung has no anatomical connection with the main inflammatory site of the bowel. Why does the inflammatory process shift from the gastrointestinal tract to the airways? The clinical and subclinical pulmonary abnormalities, dysfunction, or hyper-reactivity among IBD patients need further evaluation. Here, we give an overview of the concordance between chronic inflammatory reactions in the airways and the gastrointestinal tract. A better understanding of the possible mechanism of the crosstalk among the distant organs will be beneficial in identifying therapeutic strategies for mucosal inflammatory diseases such as IBD and allergy.

Inflammatory bowel disease: An archetype disorder of outer environment sensor systems

The pathogenesis of the two inflammatory bowel diseases (IBDs) phenotypes ulcerative colitis (UC) and Crohn's disease (CD) has remained elusive, thus frustrating attempts at defining a cure. IBD often presents as a complex inflammatory process wherein colon lesions (UC) or widespread ulceration and fissure (CD) might be accompanied by ancillary extra-intestinal manifestations involving the eye, skin, joints or liver, but also by full-blown "autoimmune" disorders from psoriasis and multiple sclerosis to rheumatoid arthritis; attempts at unraveling a link or a hierarchical order in these entities have proven almost fruitless. More recently, the input of genetics has suggested that the IBDs might be multi-organ inflammatory processes, elicited by a large number of low-penetrance susceptibility genes, with environmental factors needed to induce full-blown disease. At a noteworthy exception to this rule, the description of the nucleotide-oligomerization domain (NOD) gene mutations in CD came at the beginning of the 2000s: the NOD-LRR are part of a highly conserved microbial sensor system which respond to bacterial peptidoglycans by mounting an inflammatory response. At least in Caucasian patients, the prevalently loss-of-function mutation of NOD permitted to unexpectedly define CD as an immune deficiency state, and upon its recent description in apparently unrelated disorders such as the Blau syndrome (a granulomatous pediatric syndrome), and perhaps in psoriasis and chronic obstructive pulmonary disorders, has contributed to revolutionize our view of IBD and CD in particular. The latter affection, together with psoriasis and chronic pulmonary disease can now be included into a newly identified category named "barrier organ disease", wherein a barrier organ is defined as a large mucosal or epithelial surface with an abundant metagenomic microbial population and an underneath reactive tissue, the whole structure being in contact with the outer environment and capable to react to it. Personalized treatments and empowerment of research across different disease phenotypes should be the advantages of this novel mindset.

Inflammatory bowel disease: An archetype disorder of outer environment sensor systems

The pathogenesis of the two inflammatory bowel diseases (IBDs) phenotypes ulcerative colitis (UC) and Crohn's disease (CD) has remained elusive, thus frustrating attempts at defining a cure. IBD often presents as a complex inflammatory process wherein colon lesions (UC) or widespread ulceration and fissure (CD) might be accompanied by ancillary extra-intestinal manifestations involving the eye, skin, joints or liver, but also by full-blown "autoimmune" disorders from psoriasis and multiple sclerosis to rheumatoid arthritis; attempts at unraveling a link or a hierarchical order in these entities have proven almost fruitless. More recently, the input of genetics has suggested that the IBDs might be multi-organ inflammatory processes, elicited by a large number of low-penetrance susceptibility genes, with environmental factors needed to induce full-blown disease. At a noteworthy exception to this rule, the description of the nucleotide-oligomerization domain (NOD) gene mutations in CD came at the beginning of the 2000s: the NOD-LRR are part of a highly conserved microbial sensor system which respond to bacterial peptidoglycans by mounting an inflammatory response. At least in Caucasian patients, the prevalently loss-of-function mutation of NOD permitted to unexpectedly define CD as an immune deficiency state, and upon its recent description in apparently unrelated disorders such as the Blau syndrome (a granulomatous pediatric syndrome), and perhaps in psoriasis and chronic obstructive pulmonary disorders, has contributed to revolutionize our view of IBD and CD in particular. The latter affection, together with psoriasis and chronic pulmonary disease can now be included into a newly identified category named "barrier organ disease", wherein a barrier organ is defined as a large mucosal or epithelial surface with an abundant metagenomic microbial population and an underneath reactive tissue, the whole structure being in contact with the outer environment and capable to react to it. Personalized treatments and empowerment of research across different disease phenotypes should be the advantages of this novel mindset.

Scrambled and fried: cigarette smoke exposure causes antral follicle destruction and oocyte dysfunction through oxidative stress

Cigarette smoke is a reproductive hazard associated with pre-mature reproductive senescence and reduced clinical pregnancy rates in female smokers. Despite an increased awareness of the adverse effects of cigarette smoke exposure on systemic health, many women remain unaware of the adverse effects of cigarette smoke on female fertility. This issue is compounded by our limited understanding of the molecular mechanisms behind cigarette smoke induced infertility. In this study we used a direct nasal exposure mouse model of cigarette smoke-induced chronic obstructive pulmonary disease to characterise mechanisms of cigarette-smoke induced ovotoxicity. Cigarette smoke exposure caused increased levels of primordial follicle depletion, antral follicle oocyte apoptosis and oxidative stress in exposed ovaries, resulting in fewer follicles available for ovulation. Evidence of oxidative stress also persisted in ovulated oocytes which escaped destruction, with increased levels of mitochondrial ROS and lipid peroxidation resulting in reduced fertilisation potential. Microarray analysis of ovarian tissue correlated these insults with a complex mechanism of ovotoxicity involving genes associated with detoxification, inflammation, follicular activation, immune cell mediated apoptosis and membrane organisation. In particular, the phase I detoxifying enzyme cyp2e1 was found to be significantly up-regulated in developing oocytes; an enzyme known to cause molecular bioactivation resulting in oxidative stress. Our results provide a preliminary model of cigarette smoke induced sub-fertility through cyp2e1 bioactivation and oxidative stress, resulting in developing follicle depletion and oocyte dysfunction.

Probiotics in the management of lung diseases

The physiology and pathology of the respiratory and gastrointestinal tracts are closely related. This similarity between the two organs may underlie why dysfunction in one organ may induce illness in the other. For example, smoking is a major risk factor for COPD and IBD and increases the risk of developing Crohn's disease. Probiotics have been defined as "live microorganisms which, when administered in adequate amounts, confer health benefits on the host." In model systems probiotics regulate innate and inflammatory immune responses. Commonly used probiotics include lactic acid bacteria, particularly Lactobacillus, Bifidobacterium, and Saccharomyces, and these are often used as dietary supplements to provide a health benefit in gastrointestinal diseases including infections, inflammatory bowel disease, and colon cancer. In this respect, probiotics probably act as immunomodulatory agents and activators of host defence pathways which suggest that they could influence disease severity and incidence at sites distal to the gut. There is increasing evidence that orally delivered probiotics are able to regulate immune responses in the respiratory system. This review provides an overview of the possible role of probiotics and their mechanisms of action in the prevention and treatment of respiratory diseases.

Cystic fibrosis transmembrane conductance regulator (CFTR) allelic variants relate to shifts in faecal microbiota of cystic fibrosis patients

Introduction

In this study we investigated the effects of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene variants on the composition of faecal microbiota, in patients affected by Cystic Fibrosis (CF). CFTR mutations (F508del is the most common) lead to a decreased secretion of chloride/water, and to mucus sticky secretions, in pancreas, respiratory and gastrointestinal tracts. Intestinal manifestations are underestimated in CF, leading to ileum meconium at birth, or small bowel bacterial overgrowth in adult age.

Methods

Thirty-six CF patients, fasting and under no-antibiotic treatment, were CFTR genotyped on both alleles. Faecal samples were subjected to molecular microbial profiling through Temporal Temperature Gradient Electrophoresis and species-specific PCR. Ecological parameters and multivariate algorithms were employed to find out if CFTR variants could be related to the microbiota structure.

Results

Patients were classified by two different criteria: 1) presence/absence of F508del mutation; 2) disease severity in heterozygous and homozygous F508del patients. We found that homozygous-F508del and severe CF patients exhibited an enhanced dysbiotic faecal microbiota composition, even within the CF cohort itself, with higher biodiversity and evenness. We also found, by species-specific PCR, that potentially harmful species (Escherichia coli and Eubacterium biforme) were abundant in homozygous-F508del and severe CF patients, while beneficial species (Faecalibacterium prausnitzii, Bifidobacterium spp., and Eubacterium limosum) were reduced.

Conclusions

This is the first report that establishes a link among CFTR variants and shifts in faecal microbiota, opening the way to studies that perceive CF as a ‘systemic disease’, linking the lung and the gut in a joined axis.

Pulmonary-intestinal crosstalk in the pathological process of COPD and IBD: A perspective from the lung and the large intestine being interior-exteriorly related theory

Traditional Chinese medicine theory believes that the lung and intestine are closely related physiologically and pathologically. With the help of this, unexpected clinical efficacy can be achieved in the treatment of lung and intestinal diseases. Chronic obstructive pulmonary disease (COPD) and inflammatory bowel disease (IBD) are chronic inflammatory diseases of mucosal tissues that affect the respiratory and gastrointestinal tracts, respectively. Both COPD and IBD are driven by recurrent cycles of inflammation that lead to tissue damage and remodeling and progressively worsen symptoms. There have been no cures for either disease and both require lifelong health maintenance. Exploration of the correlation in the pathological process between COPD and IBD will help us find new ways of treatment of these two diseases.

Murine models of infectious exacerbations of airway inflammation

Airway inflammation underpins the pathogenesis of the major human chronic respiratory diseases. It is now well recognized that respiratory infections with bacteria and viruses are important in the induction, progression and exacerbation of these diseases. There are no effective therapies that prevent or reverse these events. The development and use of mouse models are proving valuable in understanding the role of infection in disease pathogenesis. They have recently been used to show that infections in early life alter immune responses and lung structure to increase asthma severity, and alter immune responses in later life to induce steroid resistance. Infection following smoke exposure or in experimental chronic obstructive pulmonary disease exacerbates inflammation and remodeling, and worsens cystic fibrosis. Further exploration of these models will facilitate the identification of new therapeutic approaches and the testing of new preventions and treatments.

Influence of age, past smoking, and disease severity on TLR2, neutrophilic inflammation, and MMP-9 levels in COPD

Chronic obstructive pulmonary disease (COPD) is a common and serious respiratory disease, particularly in older individuals, characterised by fixed airway obstruction and persistent airway neutrophilia. The mechanisms that lead to these features are not well established. We investigated the contribution of age, prior smoking, and fixed airflow obstruction on sputum neutrophils, TLR2 expression, and markers of neutrophilic inflammation. Induced sputum from adults with COPD (n = 69) and healthy controls (n = 51) was examined. A sputum portion was dispersed, total, differential cell count and viability recorded, and supernatant assayed for CXCL8, matrix metalloproteinase- (MMP-) 9, neutrophil elastase, and soluble TLR2. Peripheral blood cells (n = 7) were stimulated and TLR2 activation examined. TLR2 levels were increased with ageing, while sputum neutrophils and total sputum MMP-9 levels increased with age, previous smoking, and COPD. In multivariate regression, TLR2 gene expression and MMP-9 levels were significant independent contributors to the proportion of sputum neutrophils after adjustment for age, prior smoking, and the presence of airflow obstruction. TLR2 stimulation led to enhanced release of MMP-9 from peripheral blood granulocytes. TLR2 stimulation activates neutrophils for MMP-9 release. Efforts to understand the mechanisms of TLR2 signalling and subsequent MMP-9 production in COPD may assist in understanding neutrophilic inflammation in COPD.

Lung and intestine: a specific link in an ulcerative colitis rat model

Background. To investigate the link and mechanisms between intestine and lung in the ulcerative colitis (UC) rat model. Materials and Methods. We used the UC rat model by immunological sensitization combined with local 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) in 50% ethanol enema, observed dynamically animal general state and body weight, examined the histological and functional changes in the colon, lung, liver, and kidney tissues, and detected microvascular endothelium response towards inflammation characterized with the expression of iNOS, TXB₂, P-selectin, ICAM-1, and vascular endothelial growth factor A (VEGF-A) in the colon and lung tissue. Results. Pulmonary function results suggested ventilator disorder, and pathological findings showed interstitial pneumonia. There were no significant changes in the liver and kidney function and histopathology. The colon and lung tissue iNOS, TXB₂, P-selectin, ICAM-1, and VEGF-A expression of the model rats was significantly higher than the normal rats at both time points. Conclusions. Our study is the first to demonstrate the close association between the large intestine and lung in the immune-TNBS-ethanol-induced UC rat model. Different organs and tissues with the same embryonic origin may share the same pathological specificities in a disease. The present study provided a new way of thinking for pathological changes in clinical complex diseases manifested with multiorgan damage.

A new short-term mouse model of chronic obstructive pulmonary disease identifies a role for mast cell tryptase in pathogenesis

BACKGROUND

Cigarette smoke-induced chronic obstructive pulmonary disease (COPD) is a life-threatening inflammatory disorder of the lung. The development of effective therapies for COPD has been hampered by the lack of an animal model that mimics the human disease in a short timeframe.

OBJECTIVES

We sought to create an early-onset mouse model of cigarette smoke-induced COPD that develops the hallmark features of the human condition in a short time-frame. We also sought to use this model to better understand pathogenesis and the roles of macrophages and mast cells (MCs) in patients with COPD.

METHODS

Tightly controlled amounts of cigarette smoke were delivered to the airways of mice, and the development of the pathologic features of COPD was assessed. The roles of macrophages and MC tryptase in pathogenesis were evaluated by using depletion and in vitro studies and MC protease 6-deficient mice.

RESULTS

After just 8 weeks of smoke exposure, wild-type mice had chronic inflammation, mucus hypersecretion, airway remodeling, emphysema, and reduced lung function. These characteristic features of COPD were glucocorticoid resistant and did not spontaneously resolve. Systemic effects on skeletal muscle and the heart and increased susceptibility to respiratory tract infections also were observed. Macrophages and tryptase-expressing MCs were required for the development of COPD. Recombinant MC tryptase induced proinflammatory responses from cultured macrophages.

CONCLUSION

A short-term mouse model of cigarette smoke-induced COPD was developed in which the characteristic features of the disease were induced more rapidly than in existing models. The model can be used to better understand COPD pathogenesis, and we show a requirement for macrophages and tryptase-expressing MCs.

Netrin-1 regulates colon-kidney cross talk through suppression of IL-6 function in a mouse model of DSS-colitis

Organ cross talk is increasingly appreciated in human disease, and inflammatory mediators are shown to mediate distant organ injury in many disease models. Colitis and intestinal injury are known to be mediated by infiltrating immune cells and their secreted cytokines. However, its effect on other organs, such as the kidney, has never been studied. In the current study, we examined the effect of dextran sulfate sodium (DSS)-colitis on kidney injury and inflammation. In addition, we hypothesized that netrin-1 could modulate colon-kidney cross talk through regulation of inflammation and apoptosis. Consistent with our hypothesis, DSS-colitis induced acute kidney injury in mice. Epithelial-specific overexpression of netrin-1 suppressed both colitis and colitis-induced acute kidney injury, which was associated with reduced weight loss, neutrophil infiltration into colon mucosa, intestinal permeability, epithelial cell apoptosis, and cytokine and chemokine production in netrin-1 transgenic mice colon and kidney. To determine whether netrin-1-protective effects were mediated through suppression of IL-6, IL-6 knockout mice were treated with DSS and acute kidney injury was determined. IL-6 knockout was resistant to colitis and acute kidney injury. Moreover, administration of IL-6 to netrin-1 transgenic mice did not affect the netrin-1-protective effects on the colon and kidney, suggesting that netrin-1 may reduce both IL-6 production and its activity. The present study identifies previously unrecognized cross talk between the colon and kidney, and netrin-1 may limit distant organ injury by suppressing inflammatory mediators and apoptosis.

Sidestream smoke exposure increases the susceptibility of airway epithelia to adenoviral infection

Background

Although significant epidemiological evidence indicates that cigarette smoke exposure increases the incidence and severity of viral infection, the molecular mechanisms behind the increased susceptibility of the respiratory tract to viral pathogens are unclear. Adenoviruses are non-enveloped DNA viruses and important causative agents of acute respiratory disease. The Coxsackievirus and adenovirus receptor (CAR) is the primary receptor for many adenoviruses. We hypothesized that cigarette smoke exposure increases epithelial susceptibility to adenovirus infection by increasing the abundance of apical CAR.

Methodology and Findings

Cultured human airway epithelial cells (CaLu-3) were used as a model to investigate the effect of sidestream cigarette smoke (SSS), mainstream cigarette smoke (MSS), or control air exposure on the susceptibility of polarized respiratory epithelia to adenoviral infection. Using a Cultex air-liquid interface exposure system, we have discovered novel differences in epithelial susceptibility between SSS and MSS exposures. SSS exposure upregulates an eight-exon isoform of CAR and increases adenoviral entry from the apical surface whilst MSS exposure is similar to control air exposure. Additionally, the level of cellular glycogen synthase kinase 3β (GSK3β) is downregulated by SSS exposure and treatment with a specific GSK3β inhibitor recapitulates the effects of SSS exposure on CAR expression and viral infection.

Conclusions

This is the first time that SSS exposure has been shown to directly enhance the susceptibility of a polarized epithelium to infection by a common respiratory viral pathogen. This work provides a novel understanding of the impact of SSS on the burden of respiratory viral infections and may lead to new strategies to alter viral infections. Moreover, since GSK3β inhibitors are under intense clinical investigation as therapeutics for a diverse range of diseases, studies such as these might provide insight to extend the use of clinically relevant therapeutics and increase the understanding of potential side effects.

TGF-β-responsive myeloid cells suppress type 2 immunity and emphysematous pathology after hookworm infection

Transforming growth factor β (TGF-β) regulates inflammation, immunosuppression, and wound-healing cascades, but it remains unclear whether any of these functions involve regulation of myeloid cell function. The present study demonstrates that selective deletion of TGF-βRII expression in myeloid phagocytes i) impairs macrophage-mediated suppressor activity, ii) increases baseline mRNA expression of proinflammatory chemokines/cytokines in the lung, and iii) enhances type 2 immunity against the hookworm parasite Nippostrongylus brasiliensis. Strikingly, TGF-β-responsive myeloid cells promote repair of hookworm-damaged lung tissue, because LysM(Cre)TGF-βRII(flox/flox) mice develop emphysema more rapidly than wild-type littermate controls. Emphysematous pathology in LysM(Cre)TGF-βRII(flox/flox) mice is characterized by excessive matrix metalloprotease (MMP) activity, reduced lung elasticity, increased total lung capacity, and dysregulated respiration. Thus, TGF-β effects on myeloid cells suppress helminth immunity as a consequence of restoring lung function after infection.