Crisaborole reverses dysregulation of the mild to moderate atopic dermatitis proteome toward nonlesional and normal skin.

BACKGROUND: Safe and effective long-term topical treatments for atopic dermatitis (AD) remain limited. OBJECTIVE: In this phase 2a, single-center, intrapatient, and vehicle-controlled study, we examine the mechanism of action of crisaborole 2% ointment, a topical nonsteroidal PDE4 (phosphodiesterase-4) inhibitor, in a proteomic analysis of 40 adults with mild to moderate AD and 20 healthy subjects. METHODS: Within the AD cohort, 2 target lesions were randomized in an intrapatient (1:1) manner to double-blind crisaborole/vehicle applied twice daily for 14 days. Punch biopsy specimens were collected for biomarker analysis at baseline from all participants, then from AD patients only at day 8 (optional) and day 15. RESULTS: Compared to the vehicle, crisaborole significantly reversed dysregulation of the overall lesional proteome and of key markers and pathways (eg, Th2, Th17/Th22, and T-cell activation) associated with AD pathogenesis toward both nonlesional and normal skin. Significant clinical correlations were observed with markers associated with nociception and Th2, Th17, and neutrophilic activation. LIMITATIONS: Study limitations include predominance of white patients in the cohort, relatively short treatment time, and regimented administration of crisaborole. CONCLUSION: Our results demonstrate crisaborole-induced normalization of the AD proteome toward a nonlesional molecular phenotype and further support topical PDE4 inhibition in the treatment of mild to moderate AD.

IL-13 Controls IL-33 Activity through Modulation of ST2.

IL-33 is a multifunctional cytokine that mediates local inflammation upon tissue damage. IL-33 is known to act on multiple cell types including group 2 innate lymphoid cells (ILC2s), Th2 cells, and mast cells to drive production of Th2 cytokines including IL-5 and IL-13. IL-33 signaling activity through transmembrane ST2L can be inhibited by soluble ST2 (sST2), which acts as a decoy receptor. Previous findings suggested that modulation of IL-13 levels in mice lacking decoy IL-13Rα2, or mice lacking IL-13, impacted responsiveness to IL-33. In this study, we used Il13 -/- mice to investigate whether IL-13 regulates IL-33 activity by modulating the transmembrane and soluble forms of ST2. In Il13 -/- mice, the effects of IL-33 administration were exacerbated relative to wild type (WT). Il13 -/- mice administered IL-33 i.p. had heightened splenomegaly, more immune cells in the peritoneum including an expanded ST2L+ ILC2 population, increased eosinophilia in the spleen and peritoneum, and reduced sST2 in the circulation and peritoneum. In the spleen, lung, and liver of mice given IL-33, gene expression of both isoforms of ST2 was increased in Il13 -/- mice relative to WT. We confirmed fibroblasts to be an IL-13-responsive cell type that can regulate IL-33 activity through production of sST2. This study elucidates the important regulatory activity that IL-13 exerts on IL-33 through induction of IL-33 decoy receptor sST2 and through modulation of ST2L+ ILC2s.

Suppression of immunoglobulin E-mediated allergic responses by regulator of G protein signaling 13.

Mast cells elicit allergic responses through degranulation and release of proinflammatory mediators after antigen crosslinking of the immunoglobulin E receptor FcepsilonRI. Proteins of the 'regulator of G protein signaling' (RGS) family negatively control signaling mediated by G protein-coupled receptors through GTPase-accelerating protein activity. Here we show that RGS13 inhibited allergic responses by physically interacting with the regulatory p85alpha subunit of phosphatidylinositol-3-OH kinase in mast cells and disrupting its association with an FcepsilonRI-activated scaffolding complex. Rgs13-/- mice had enhanced immunoglobulin E-mediated mast cell degranulation and anaphylaxis. Thus, RGS13 inhibits the assembly of immune receptor-induced signalosomes in mast cells. Abnormal RGS13 expression or function may contribute to disorders of amplified mast cell activity, such as idiopathic anaphylaxis.

Modulation of the IL-33/IL-13 Axis in Obesity by IL-13Rα2.

In obesity, IL-13 overcomes insulin resistance by promoting anti-inflammatory macrophage differentiation in adipose tissue. Endogenous IL-13 levels can be modulated by the IL-13 decoy receptor, IL-13Rα2, which inactivates and depletes the cytokine. In this study, we show that IL-13Rα2 is markedly elevated in adipose tissues of obese mice. Mice deficient in IL-13Rα2 had high expression of IL-13 response markers in adipose tissue, consistent with increased IL-13 activity at baseline. Moreover, exposure to the type 2 cytokine-inducing alarmin, IL-33, enhanced serum and tissue IL-13 concentrations and elevated tissue eosinophils, macrophages, and type 2 innate lymphoid cells. IL-33 also reduced body weight, fat mass, and fasting blood glucose levels. Strikingly, however, the IL-33-induced protection was greater in IL-13Rα2-deficient mice compared with wild-type littermates, and these changes were largely attenuated in mice lacking IL-13. Although IL-33 administration improved the metabolic profile in the context of a high fat diet, it also resulted in diarrhea and perianal irritation, which was enhanced in the IL-13Rα2-deficient mice. Weight loss in this group was associated with reduced food intake, which was likely related to the gastrointestinal effects. These findings outline both potentially advantageous and deleterious effects of a type 2-skewed immune response under conditions of metabolic stress, and identify IL-13Rα2 as a critical checkpoint in adipose tissues that limits the protective effects of the IL-33/IL-13 axis in obesity.

Alternative splicing of interleukin-33 and type 2 inflammation in asthma.

Type 2 inflammation occurs in a large subgroup of asthmatics, and novel cytokine-directed therapies are being developed to treat this population. In mouse models, interleukin-33 (IL-33) activates lung resident innate lymphoid type 2 cells (ILC2s) to initiate airway type 2 inflammation. In human asthma, which is chronic and difficult to model, the role of IL-33 and the target cells responsible for persistent type 2 inflammation remain undefined. Full-length IL-33 is a nuclear protein and may function as an "alarmin" during cell death, a process that is uncommon in chronic stable asthma. We demonstrate a previously unidentified mechanism of IL-33 activity that involves alternative transcript splicing, which may operate in stable asthma. In human airway epithelial cells, alternative splicing of the IL-33 transcript is consistently present, and the deletion of exons 3 and 4 (Δ exon 3,4) confers cytoplasmic localization and facilitates extracellular secretion, while retaining signaling capacity. In nonexacerbating asthmatics, the expression of Δ exon 3,4 is strongly associated with airway type 2 inflammation, whereas full-length IL-33 is not. To further define the extracellular role of IL-33 in stable asthma, we sought to determine the cellular targets of its activity. Comprehensive flow cytometry and RNA sequencing of sputum cells suggest basophils and mast cells, not ILC2s, are the cellular sources of type 2 cytokines in chronic asthma. We conclude that IL-33 isoforms activate basophils and mast cells to drive type 2 inflammation in chronic stable asthma, and novel IL-33 inhibitors will need to block all biologically active isoforms.

Low sputum MMP-9/TIMP ratio is associated with airway narrowing in smokers with asthma.

Asthmatic smokers have poor symptom control and accelerated decline in lung function. A reduced ratio of matrix metalloproteinase (MMP)-9/tissue inhibitors of metalloproteinases (TIMPs) in nonsmokers with asthma has been implicated in airway remodelling. We tested the hypothesis that sputum MMP-9 activity/TIMPs ratios are reduced in smokers compared with never-smokers with asthma and are associated with reduced lung function and altered computed tomography (CT) measures of airway wall dimensions. Lung function, airway dimensions by CT, and induced sputum concentrations (and activity) of MMP-9 and TIMP-1 and -2 were measured in 81 asthmatics and 43 healthy subjects (smokers and never-smokers). Respiratory epithelial MMP9 and TIMP mRNA was quantified in 31 severe asthmatics and 32 healthy controls. Sputum MMP-9 activity/TIMP-1 and TIMP-2 ratios, and nasal epithelial MMP9/TIMP1 and MMP9/TIMP2 expression ratios were reduced in smokers with asthma compared with never-smokers with asthma. Low sputum ratios in asthmatic smokers were associated with reduced post-bronchodilator forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity ratio and segmental airway lumen area. The association of a low sputum MMP-9 activity/TIMP-1 ratio with persistent airflow obstruction and reduced CT airway lumen area in smokers with asthma may indicate that an imbalance of MMP-9 and TIMPs contributes to structural changes to the airways in this group.

Sputum matrix metalloproteinase-12 in patients with chronic obstructive pulmonary disease and asthma: relationship to disease severity.

BACKGROUND: Matrix metalloproteinase (MMP)-12 has been implicated in the pathogenesis of both chronic obstructive pulmonary disease (COPD) and asthma. The influence of disease severity on sputum MMP-12 concentrations and activity is not known. OBJECTIVES: We sought to examine the relationship between disease severity assessed by means of lung function and computed tomography (CT) and induced sputum MMP-12 concentrations and activity in patients with asthma and COPD. METHODS: In 208 subjects (109 asthmatic patients, smokers and never smokers, mild, moderate, and severe; 53 patients with COPD, smokers and exsmokers, mild, moderate, and severe; and 46 healthy control subjects, smokers and never smokers), we measured induced sputum MMP-12 concentrations (ELISA) and enzyme activity (fluorescence resonance energy transfer), sputum cell MMP12 mRNA expression (quantitative PCR [qPCR]), diffusing capacity for carbon monoxide (Dlco), and CT assessment of emphysema (percentage of low-attenuation areas at less -950 Hounsfield units). RESULTS: Sputum MMP-12 concentrations are greater in patients with COPD and smokers with asthma than in healthy nonsmokers (P = .003 and P = .035, respectively) but similar to those seen in healthy smokers. In patients with COPD, disease severity, when measured by means of CT-assessed emphysema, but not by means of spirometry or Dlco values, is directly associated with sputum MMP-12 concentrations and activity. In the asthma groups there is no significant association between disease severity and sputum MMP-12 concentrations or activity. CONCLUSIONS: Sputum MMP-12 concentrations and activity in patients with COPD are directly associated with the extent of emphysema measured by means of CT. This finding supports a role for MMP-12 in the pathogenesis of COPD and might suggest that blocking MMP-12 activity in patients with COPD could prevent the further development of emphysema.

Acidic mammalian chitinase is not a critical target for allergic airway disease.

The expression of acidic mammalian chitinase (AMCase) is associated with Th2-driven respiratory disorders. To investigate the potentially pathological role of AMCase in allergic airway disease (AAD), we sensitized and challenged mice with ovalbumin or a combination of house dust mite (HDM) plus cockroach allergen. These mice were treated or not treated with small molecule inhibitors of AMCase, which significantly reduced allergen-induced chitinolytic activity in the airways, but exerted no apparent effect on pulmonary inflammation per se. Transgenic and AMCase-deficient mice were also submitted to protocols of allergen sensitization and challenge, yet we found little or no difference in the pattern of AAD between mutant mice and wild-type (WT) control mice. In a separate model, where mice were challenged only with intratracheal instillations of HDM without adjuvant, total bronchoalveolar lavage (BAL) cellularity, inflammatory infiltrates in lung tissues, and lung mechanics remained comparable between AMCase-deficient mice and WT control mice. However BAL neutrophil and lymphocyte counts were significantly increased in AMCase-deficient mice, whereas concentrations in BAL of IL-13 were significantly decreased compared with WT control mice. These results indicate that, although exposure to allergen stimulates the expression of AMCase and increased chitinolytic activity in murine airways, the overexpression or inhibition of AMCase exerts only a subtle impact on AAD. Conversely, the increased numbers of neutrophils and lymphocytes in BAL and the decreased concentrations of IL-13 in AMCase-deficient mice challenged intratracheally with HDM indicate that AMCase contributes to the Th1/Th2 balance in the lungs. This finding may be of particular relevance to patients with asthma and increased airway neutrophilia.

Smoke exposure of human macrophages reduces HDAC3 activity, resulting in enhanced inflammatory cytokine production.

Chronic obstructive pulmonary disease (COPD) is a debilitating condition resulting from exposure to pollutants such as cigarette smoke. Pulmonary macrophages secrete a plethora of inflammatory mediators that are increased in the lungs of COPD patients, but whether this phenotype results directly from smoke exposure remains unknown. Using an in vitro model for alveolar macrophages (AM) derived from human peripheral blood monocytes with granulocyte-macrophage stimulating factor (GM-MØ), we analyzed the mechanistic connection between cigarette smoke exposure and histone deacetylase (HDAC) regulation, hypothesized to be a contributing factor in COPD pathophysiology. Here we show that acute smoke exposure inhibits HDAC enzymatic activity in GM-MØ. Analysis of mRNA and total cellular proteins for expression of class I (1, 2, 3 and 8), class II (4, 5, 6, 7, 9, 10), and class IV (11) HDAC revealed no effect of smoke exposure, whereas nuclear HDAC3 protein content was reduced. To better understand the physiological significance of reduced HDAC3 activity, we utilized siRNA to knockdown HDAC1, 2 and 3 individually. Interestingly, siRNA-mediated reduction of HDAC3 resulted in increased production of IL8 and IL1ß in response to LPS stimulation, while HDAC2 knockdown had no effect on either cytokine. Lower nuclear content of HDAC3 in the context of equivalent total HDAC protein levels following smoke exposure may reflect increased nuclear export of HDAC3, allowing increased nuclear factor kappa b (NF-κB ) driven cytokine expression that can contribute to inflammation.

Complement C3a, CpG oligos, and DNA/C3a complex stimulate IFN-α production in a receptor for advanced glycation end product-dependent manner.

The receptor for advanced glycation end products (RAGE) is a multiligand transmembrane receptor implicated in a number of diseases including autoimmune diseases. To further understand the pathogenic mechanism of RAGE in these diseases, we searched for additional ligands. We discovered that C3a bound to RAGE with an EC(50) of 1.9 nM in an ELISA, and the binding was increased both in magnitude (by >2-fold) and in affinity (EC(50) 70 pM) in the presence of human stimulatory unmethylated cytosine-guanine-rich DNA A (hCpGAs). Surface plasmon resonance and fluorescence anisotropy analyses demonstrated that hCpGAs could bind directly to RAGE and C3a and form a ternary complex. In human PBMCs, C3a increased IFN-α production in response to low levels of hCpGAs, and this synergy was blocked by soluble RAGE or by an Ab directed against RAGE. IFN-α production was reduced in response to mouse CpGAs and C3a in RAGE(-/-) mouse bone marrow cells compared wild-type mice. Taken together, these data demonstrate that RAGE is a receptor for C3a and CpGA. Through direct interaction, C3a and CpGA synergize to increase IFN-α production in a RAGE-dependent manner and stimulate an innate immune response. These findings indicate a potential role of RAGE in autoimmune diseases that show accumulation of immunostimulatory DNA and C3a.

Discovery and multi-parametric optimization of a high-affinity antibody against interleukin-25 with neutralizing activity in a mouse model of skin inflammation.

Background: Interleukin (IL)25 has been implicated in tissue homeostasis at barrier surfaces and the initiation of type two inflammatory signaling in response to infection and cell injury across multiple organs. We sought to discover and engineer a high affinity neutralizing antibody and evaluate the antibody functional activity in vitro and in vivo. Methods: In this study, we generated a novel anti-IL25 antibody (22C7) and investigated the antibody's therapeutic potential for targeting IL25 in inflammation. Results: A novel anti-IL25 antibody (22C7) was generated with equivalent in vitro affinity and potency against the human and mouse orthologs of the cytokine. This translated into in vivo potency in an IL25-induced air pouch model where 22C7 inhibited the recruitment of monocytes, macrophages, neutrophils and eosinophils. Furthermore, 22C7 significantly reduced ear swelling, acanthosis and disease severity in the Aldara mouse model of psoriasiform skin inflammation. Given the therapeutic potential of IL25 targeting in inflammatory conditions, 22C7 was further engineered to generate a highly developable, fully human antibody while maintaining the affinity and potency of the parental molecule. Conclusions: The generation of 22C7, an anti-IL25 antibody with efficacy in a preclinical model of skin inflammation, raises the therapeutic potential for 22C7 use in the spectrum of IL25-mediated diseases.

Mast cell-dependent contraction of human airway smooth muscle cell-containing collagen gels: influence of cytokines, matrix metalloproteases, and serine proteases.

In asthma, mast cells infiltrate the airway smooth muscle cell layer and secrete proinflammatory and profibrotic agents that contribute to airway remodeling. To study the effects of mast cell activation on smooth muscle cell-dependent matrix contraction, we developed coculture systems of human airway smooth muscle cells (HASM) with primary human mast cells derived from circulating progenitors or with the HMC-1 human mast cell line. Activation of primary human mast cells by IgE receptor cross-linking or activation of HMC-1 cells with C5a stimulated contraction of HASM-embedded collagen gels. Contractile activity could be transferred with conditioned medium from activated mast cells, implicating involvement of soluble factors. Cytokines and proteases are among the agents released by activated mast cells that may promote a contractile response. Both IL-13 and IL-6 enhanced contraction in this model and the activity of IL-13 was ablated under conditions leading to expression of the inhibitory receptor IL-13Ralpha2 on HASM. In addition to cytokines, matrix metalloproteinases (MMPs), and serine proteases induced matrix contraction. Inhibitor studies suggested that, although IL-13 could contribute to contraction driven by mast cell activation, MMPs were critical mediators of the response. Both MMP-1 and MMP-2 were strongly expressed in this system. Serine proteases also contributed to contraction induced by mast cell-activating agents and IL-13, most likely by mediating the proteolytic activation of MMPs. Hypercontractility is a hallmark of smooth muscle cells in the asthmatic lung. Our findings define novel mechanisms whereby mast cells may modulate HASM-driven contractile responses.

A fluorescent assay suitable for inhibitor screening and vanin tissue quantification.

Vanin-1 is a pantetheinase that catalyzes the hydrolysis of pantetheine to produce pantothenic acid (vitamin B5) and cysteamine. Reported here is a highly sensitive fluorescent assay using a novel fluorescently labeled pantothenate derivative. The assay has been used for characterization of a soluble version of human vanin-1 recombinant protein, identification and characterization of hits from high-throughput screening (HTS), and quantification of vanin pantothenase activity in cell lines and tissues. Under optimized assay conditions, we quantified vanin pantothenase activity in tissue lysate and found low activity in lung and liver but high activity in kidney. We demonstrated that the purified recombinant vanin-1 consisting of the extracellular portion without the glycosylphosphatidylinositol (GPI) linker was highly active with an apparent K(m) of 28 microM for pantothenate-7-amino-4-methylcoumarin (pantothenate-AMC), which was converted to pantothenic acid and AMC based on liquid chromatography-mass spectrometry (LC-MS) analysis. The assay also performed well in a 384-well microplate format under initial rate conditions (10% conversion) with a signal-to-background ratio (S/B) of 7 and a Z factor of 0.75. Preliminary screening of a library of 1280 pharmaceutically active compounds identified inhibitors with novel chemical scaffolds. This assay will be a powerful tool for target validation and drug lead identification and characterization.

RGS13 controls g protein-coupled receptor-evoked responses of human mast cells.

IgE-mediated mast cell degranulation and release of vasoactive mediators induced by allergens elicits allergic responses. Although G protein-coupled receptor (GPCR)-induced signals may amplify IgE-dependent degranulation, how GPCR signaling in mast cells is regulated remains incompletely defined. We investigated the role of regulator of G protein signaling (RGS) proteins in the modulation of these pathways in human mast cells. Several RGS proteins were expressed in mast cells including RGS13, which we previously showed inhibited IgE-mediated mast cell degranulation and anaphylaxis in mice. To characterize how RGS13 affects GPCR-mediated functions of human mast cells, we analyzed human mast cell lines (HMC-1 and LAD2) depleted of RGS13 by specific small interfering RNA or short hairpin RNA and HMC-1 cells overexpressing RGS13. Transient RGS13 knockdown in LAD2 cells lead to increased degranulation to sphingosine-1-phosphate but not to IgE-Ag or C3a. Relative to control cells, HMC-1 cells stably expressing RGS13-targeted short hairpin RNA had greater Ca(2+) mobilization in response to several natural GPCR ligands such as adenosine, C5a, sphingosine-1-phosphate, and CXCL12 than wild-type cells. Akt phosphorylation, chemotaxis, and cytokine (IL-8) secretion induced by CXCL12 were also greater in short hairpin RGS13-HMC-1 cells compared with control. RGS13 overexpression inhibited CXCL12-evoked Ca(2+) mobilization, Akt phosphorylation and chemotaxis. These results suggest that RGS13 restricts certain GPCR-mediated biological responses of human mast cells.

Human alveolar macrophage gene responses to Mycobacterium tuberculosis strains H37Ra and H37Rv.

H37Rv and H37Ra have been widely used as models of virulent and avirulent strains, respectively, of Mycobacterium tuberculosis. Since the sequencing of H37Rv, microarrays have been used to investigate gene expression of M. tuberculosis strains under various conditions, and to compare gene expression of specific isolates of the organism. Because differences in the virulence of these organisms could also be manifest via their differential induction of host genes, we used Affymetrix Human Genome Arrays U133A and U133B to evaluate human alveolar macrophage (AM) responses to infection with H37Rv and H37Ra. H37Rv altered expression of far more genes than did H37Ra. Moreover, the genes induced by H37Rv to a greater extent than by H37Ra were predominantly associated with the development of effective immunity. H37Rv markedly increased expression of IL-23 p19, whereas neither organism significantly induced IL-12 p35 expression. Quantitative PCR confirmed that H37Rv induced significantly more AM p19 expression than did H37Ra. After low-level infection of both AM and peripheral blood monocytes (MN) with H37Rv, neither cell type produced IL-12 (by ELISA). In contrast, AM displayed significant IL-23 production in response to H37Rv, whereas MN did not. Our findings thus suggest an important role for IL-23 in human host responses to pulmonary infection with M. tuberculosis, and are consistent with epidemiologic and genetic studies that imply that H37Rv may not have unusual capacity to cause human disease.

In vitro modeling of human alveolar macrophage smoke exposure: enhanced inflammation and impaired function.

Pulmonary macrophages (MØs) are essential for clearance of inhaled particles, innate immunity, and lung tissue maintenance. However, the products of activated MØs have also been implicated in inflammation and tissue destruction, including in chronic obstructive pulmonary disease (COPD). Primary human alveolar macrophages (AMs) are available in limited numbers via bronchoalveolar lavage (BAL) or sputum induction, and BAL macrophages are not commonly available to all researchers. A readily available, plentiful, but representative surrogate for AMs would advance understanding of the contribution of macrophages to lung pathophysiology. Herein the authors describe a method for the in vitro derivation of AM-like cells using primary human peripheral blood monocytes differentiated in suspension with granulocyte-macrophage colony-stimulating factor (GM-CSF). The method produces a cell population with a consistent and stable phenotype. Flow cytometry reveals that GM-CSF-derived macrophages (GM-MØs) express lineage markers, immunoglobulin gamma (Fc gamma) receptors, adhesion molecules, antigen presentation coreceptors, and scavenger receptors akin to AMs. Functionally, cigarette smoke activates extracellular signal-related kinase (ERK) and p38 mitogen-activated protein (MAP) kinase, enhances interleukin 8 (IL8) production from GM-MØs and inhibits phagocytosis, phenotypes previously described for smokers' AMs. Global transcriptional profiling revealed significant overlap in regulated genes between smokers' AMs and GM-MØs treated with cigarette smoke preparations in vitro.

IL1RL1 asthma risk variants regulate airway type 2 inflammation.

Genome-wide association studies of asthma have identified genetic variants in the IL1RL1 gene, but the molecular mechanisms conferring risk are unknown. IL1RL1 encodes the ST2 receptor (ST2L) for IL-33 and an inhibitory decoy receptor (sST2). IL-33 promotes type 2 inflammation, which is present in some but not all asthmatics. We find that two single nucleotide polymorphisms (SNPs) in IL1RL1 - rs1420101 and rs11685480 - are strongly associated with plasma sST2 levels, though neither is an expression quantitative trait locus (eQTL) in whole blood. Rather, rs1420101 and rs11685480 mark eQTLs in airway epithelial cells and distal lung parenchyma, respectively. We find that the genetically determined plasma sST2 reservoir, derived from the lung, neutralizes IL-33 activity, and these eQTL SNPs additively increase the risk of airway type 2 inflammation among asthmatics. These risk variants define a population of asthmatics at risk of IL-33-driven type 2 inflammation.

Developing predictive assays: the phenotypic screening "rule of 3".

Phenotypic drug discovery approaches can positively affect the translation of preclinical findings to patients. However, not all phenotypic assays are created equal. A critical question then follows: What are the characteristics of the optimal assays? We analyze this question and propose three specific criteria related to the disease relevance of the assay-system, stimulus, and end point-to help design the most predictive phenotypic assays.

Sputum matrix metalloproteinase-9 is associated with the degree of emphysema on computed tomography in COPD.

BACKGROUND: Matrix-metalloproteinase (MMP)-9 has been implicated in the pathogenesis of COPD, although its link to disease severity is unclear. The purpose of the study was to examine the relationship between disease severity assessed by lung function and computed tomography (CT) and sputum MMP-9 expression, concentration and activity in patients with COPD. FINDINGS: In 53 COPD subjects, smokers and ex-smokers; 46 healthy controls, smokers and never smokers, we measured sputum MMP-9 concentrations (ELISA) and enzyme activity (FRET), sputum MMP-9 mRNA expression, spirometry, diffusing capacity for carbon monoxide (DLco) and CT assessment of emphysema (% low attenuation areas below-950 Hounsfield units). Sputum MMP-9 concentrations and mRNA expression in COPD subjects were significantly greater than in healthy never-smokers (p = 0.007 and p = 0.001 respectively) and similar to those in healthy smokers. Disease severity when assessed by the extent of emphysema measured by CT, but not by spirometry or DLco values, was directly associated with sputum MMP-9 concentrations [r = 0.442 (0.171, 0.634), p = 0.020], and MMP-9 activity [r = 0.447 (0.219, 0.643), p = 0.010]. In moderate to severe COPD, increased MMP-9 mRNA expression levels were associated with reduced post-bronchodilator FEV1 [r = -0.530 (-0.686, -0.327), p < 0.001], FEV1/FVC ratio [r = -0.551 (-0.701, -0.354), p < 0.001] and reduced DLco [r = -0.399 (-539, -0.102), p = 0.048]. CONCLUSIONS: Sputum MMP-9 concentrations in COPD are directly associated with the extent of emphysema measured by CT and MMP-9 expression levels are inversely associated with DLco. These findings support a role for MMP-9 in the pathogenesis of COPD.

Identification of a chemical probe for bromo and extra C-terminal bromodomain inhibition through optimization of a fragment-derived hit.

The posttranslational modification of chromatin through acetylation at selected histone lysine residues is governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). The significance of this subset of the epigenetic code is interrogated and interpreted by an acetyllysine-specific protein-protein interaction with bromodomain reader modules. Selective inhibition of the bromo and extra C-terminal domain (BET) family of bromodomains with a small molecule is feasible, and this may represent an opportunity for disease intervention through the recently disclosed antiproliferative and anti-inflammatory properties of such inhibitors. Herein, we describe the discovery and structure-activity relationship (SAR) of a novel, small-molecule chemical probe for BET family inhibition that was identified through the application of structure-based fragment assessment and optimization techniques. This has yielded a potent, selective compound with cell-based activity (PFI-1) that may further add to the understanding of BET family function within the bromodomains.