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H A Chapman

Publications and source records attributed to H A Chapman.

At least 19 recordsLinked to original sources
PubMed2004

Familial aggregation of FEF(25-75) and FEF(25-75)/FVC in families with severe, early onset COPD.

BACKGROUND: The Boston Early-Onset COPD study showed that current or ex-smoking first degree relatives of severe early onset COPD probands have significantly lower forced expiratory volume in 1 second (FEV(1)) and FEV(1)/forced vital capacity (FVC) values than current or ex-smoking control subjects, which suggests the existence of genetic risk factors for the development of COPD in response to cigarette smoking. We hypothesised that first degree relatives of early onset COPD probands may also have lower values of spirometric parameters such as forced expiratory flow at the mid-portion of forced vital capacity (FEF(25-75)) and FEF(25-75)/FVC. METHODS: Using generalised estimating equations, FEF(25-75) and FEF(25-75)/FVC were analysed in 333 first degree relatives of probands with severe early onset COPD and 83 population based controls; analyses were also performed on data stratified by smoking status. Narrow sense heritability estimates were calculated using a variance component approach. RESULTS: Significantly lower FEF(25-75) and FEF(25-75)/FVC were observed in smoking (FEF(25-75): beta -0.788 l/s (95% CI -1.118 to -0.457), FEF(25-75)/FVC: beta -20.4% (95% CI -29.3 to -11.6, p<0.0001 for both phenotypes) and non-smoking (FEF(25-75): beta -0.357 l/s (95% CI -0.673 to -0.041, p = 0.0271), FEF(25-75)/FVC: beta -9.5% (95% CI -17.1 to -1.9, p = 0.0145)) first degree relatives of early onset COPD probands. Narrow sense heritability estimates for FEF(25-75) (h(2) = 0.38) and FEF(25-75)/FVC (h(2) = 0.45) were similar to those for FEV(1) and FEV(1)/FVC. CONCLUSION: Lower values of FEF(25-75) and FEF(25-75)/FVC in non-smoking first degree relatives of early onset COPD probands than in controls suggest a genetic susceptibility to develop obstructive lung disease, independent of smoking, which is magnified by exposure to deleterious environments as suggested by the further decrements in FEF(25-75) and FEF(25-75)/FVC seen in smoking first degree relatives. FEF(25-75) and FEF(25-75)/FVC have high heritability and are important intermediate phenotypes for inclusion in genetic epidemiological studies of COPD.

Adolescent↗
PubMed2003

Deficiency of the cysteine protease cathepsin S impairs microvessel growth.

During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S-deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S-deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

Animals↗
PubMed2001

Expression of cathepsins B and S in the progression of prostate carcinoma.

Cathepsins B and S (CatB, CatS) are lysosomal cysteine proteases which, among other functions, appear to play a role in cancer progression in different tumor models due to their matrix-degrading properties. To investigate their possible involvement in the development of prostate carcinoma, we immunohistochemically analyzed CatB and CatS in 38 primary human prostatic adenocarcinomas, as well as concomitant high-grade prostatic intra-epithelial neoplasia, nodular hyperplasia and normal tissue. CatB expression was observed in 28 (74%) and CatS in 32 (84%) carcinomas, being concomitant in 24 cases (63%). High-grade intra-epithelial neoplasia expressed CatB in 20/23 cases (87%), and a similar result was obtained for CatS, with expression of both coinciding in 18 cases (78%). In non-neoplastic tissue, strong expression of both proteases was observed in macrophages, inflamed glands and transitional metaplasia, whereas atrophic glands and basal cells of normal glands displayed intense CatB positivity. We conclude that CatB and CatS are often expressed together in neoplastic prostatic cells from pre-invasive to invasive and clinically detectable stages, suggesting a putative role in local invasion, though other functions cannot be ruled out.

Adenocarcinoma↗
PubMed2001

Regulation of CD1 function and NK1.1(+) T cell selection and maturation by cathepsin S.

NK1.1(+) T cells develop and function through interactions with cell surface CD1 complexes. In I-A(b) mice lacking the invariant chain (Ii) processing enzyme, cathepsin S, NK1.1(+) T cell selection and function are impaired. In vitro, thymic dendritic cells (DCs) from cathepsin S(-/-) mice exhibit defective presentation of the CD1-restricted antigen, alpha-galactosylceramide (alpha-GalCer). CD1 dysfunction is secondary to defective trafficking of CD1, which colocalizes with Ii fragments and accumulates within endocytic compartments of cathepsin S(-/-) DCs. I-A(k), cathepsin S(-/-) mice do not accumulate class II-associated Ii fragments and accordingly do not display CD1 abnormalities. Thus, function of CD1 is critically linked to processing of Ii, revealing MHC class II haplotype and cathepsin S activity as regulators of NK T cells.

Animals↗
PubMed2001

Urokinase receptors promote beta1 integrin function through interactions with integrin alpha3beta1.

The urokinase receptor (uPAR) is linked to cellular migration through its capacity to promote pericellular proteolysis, regulate integrin function, and mediate cell signaling in response to urokinase (uPA) binding. The mechanisms for these activities remain incompletely defined, although uPAR was recently identified as a cis-acting ligand for the beta2 integrin CD11b/CD18 (Mac-1). Here we show that a major beta1 integrin partner for uPAR/uPA signaling is alpha3. In uPAR-transfected 293 cells uPAR complexed (>90%) with alpha3beta1 and antibodies to alpha3 blocked uPAR-dependent vitronectin (Vn) adhesion. Soluble uPAR bound to recombinant alpha3beta1 in a uPA-dependent manner (K(d) < 20 nM) and binding was blocked by a 17-mer alpha3beta1 integrin peptide (alpha325) homologous to the CD11b uPAR-binding site. uPAR colocalized with alpha3beta1 in MDA-MB-231 cells and uPA (1 nM) enhanced spreading and focal adhesion kinase phosphorylation on fibronectin (Fn) or collagen type I (Col) in a pertussis toxin- and alpha325-sensitive manner. A critical role of alpha3beta1 in uPA signaling was verified by studies of epithelial cells from alpha3-deficient mice. Thus, uPAR preferentially complexes with alpha3beta1, promoting direct (Vn) and indirect (Fn, Col) pathways of cell adhesion, the latter a heterotrimeric G protein-dependent mechanism of signaling between alpha3beta1 and other beta1 integrins.

Binding Sites↗
PubMed2001

Protease crosstalk with integrins: the urokinase receptor paradigm.

Migratory cells use both adhesion receptors and proteolytic enzymes to regulate their interaction with and response to extracellular matrices. Cooperation between integrins and proteases operates at several levels: integrin signaling induces proteases, proteases co-localize with integrins, and proteases regulate the interface between integrins and the intracellular cytoskeleton. One protease system intimately connected to integrins is the urokinase/urokinase receptor(uPAR)/plasmin system. Recent studies indicate urokinase promotes the ligand-like binding of its receptor to a set of beta1 and beta2 integrins, this binding in turn affecting integrin signaling and cell migration. The glycolipid anchor of uPAR associates with cholesterol-rich membrane rafts. Binding of uPAR to integrins may enrich integrin clusters with signaling molecules such as src-family kinases that localize to rafts and are important to integrin function. Signals derived from integrin/uPAR complexes promote the function of other integrins. Thus the urokinase/plasmin system coordinates with integrins to regulate cell: matrix interactions.

Endopeptidases↗
PubMed2000

Interferon gamma induction of pulmonary emphysema in the adult murine lung.

Chronic inflammation containing CD8(+) lymphocytes, neutrophils, and macrophages, and pulmonary emphysema coexist in lungs from patients with chronic obstructive pulmonary disease. Although this inflammatory response is believed to cause the remodeling that is seen in these tissues, the mechanism(s) by which inflammation causes emphysema have not been defined. Here we demonstrate that interferon gamma (IFN-gamma), a prominent product of CD8(+) cells, causes emphysema with alveolar enlargement, enhanced lung volumes, enhanced pulmonary compliance, and macrophage- and neutrophil-rich inflammation when inducibly targeted, in a transgenic fashion, to the adult murine lung. Prominent protease and antiprotease alterations were also noted in these mice. They included the induction and activation of matrix metalloproteinase (MMP)-12 and cathepsins B, H, D, S, and L, the elaboration of MMP-9, and the selective inhibition of secretory leukocyte proteinase inhibitor. IFN-gamma causes emphysema and alterations in pulmonary protease/antiprotease balance when expressed in pulmonary tissues.

Animals↗
PubMed2000

Importance of lysosomal cysteine proteases in lung disease.

The human lysosomal cysteine proteases are a family of 11 proteases whose members include cathepsins B, C, H, L, and S. The biology of these proteases was largely ignored for decades because of their lysosomal location and the belief that their function was limited to the terminal degradation of proteins. In the past 10 years, this view has changed as these proteases have been found to have specific functions within cells. This review highlights some of these functions, specifically their roles in matrix remodeling and in regulating the immune response, and their relationship to lung diseases.

Animals↗
PubMed2000

Simple modifications of the serpin reactive site loop convert SCCA2 into a cysteine proteinase inhibitor: a critical role for the P3' proline in facilitating RSL cleavage.

The human squamous cell carcinoma antigens (SCCA) 1 and 2 are members of the serpin family that are 92% identical in their amino acid sequence. Despite this similarity, they inhibit distinct classes of proteinases. SCCA1 neutralizes the papain-like cysteine proteinases, cathepsins (cat) S, L, and K; and SCCA2 inhibits the chymotrypsin-like serine proteinases, catG and human mast cell chymase. SCCA2 also can inhibit catS, as well as other papain-like cysteine proteinases, albeit at a rate 50-fold less than that of SCCA1. Analysis of the mechanism of inhibition by SCCA1 revealed that the reactive site loop (RSL) is important for cysteine proteinase inhibition. The inhibition of catS by a mutant SCCA2 containing the RSL of SCCA1 is comparable to that of wild-type SCCA1. This finding suggested that there were no motifs outside and only eight residues within the RSL that were directing catS-specific inhibition. The purpose of this study was to determine which of these residues might account for the marked difference in the ability of SCCA1 and SCCA2 to inhibit papain-like cysteine proteinases. SCCA2 molecules containing different RSL mutations showed that no single amino acid substitution could convert SCCA2 into a more potent cysteine proteinase inhibitor. Rather, different combinations of mutations led to incremental increases in catS inhibitory activity with residues in four positions (P1, P3', P4', and P11') accounting for 80% of the difference in activity between SCCA1 and SCCA2. Interestingly, the RSL cleavage site differed between wild-type SCCA2 and this mutant. Moreover, these data established the importance of a Pro residue in the P3' position for efficient inhibition of catS by both wild-type SCCA1 and mutated SCCA2. Molecular modeling studies suggested that this residue might facilitate positioning of the RSL within the active site of the cysteine proteinase.

Amino Acid Sequence↗
PubMed2000

Identification of a urokinase receptor-integrin interaction site. Promiscuous regulator of integrin function.

Adhesion and signaling by integrins require their dynamic association with nonintegrin membrane proteins. One such protein, the glycolipid-anchored urokinase receptor (uPAR), associates with and modifies the function of the beta(2)-integrin Mac-1 (CD11b/CD18). In this study, a critical non-I-domain binding site for uPAR on CD11b (M25; residues 424-440) is identified by homology with a phage display peptide known to bind uPAR. Recombinant soluble uPAR and cells expressing uPAR bound to immobilized M25, binding being promoted by urokinase and blocked by soluble M25, but not a scrambled control or homologous peptides from other beta(2)-associated alpha-chains. Mac-1, but not a mutated Mac-1 in which M25 was replaced with the homologous sequence of CD11c, co-precipitated with uPAR. In the beta-propeller model of alpha-chain folding, M25 spans an exposed loop on the ligand-binding, upper surface of alphaM, identifying uPAR as an atypical alphaM ligand. Although not blocking ligand binding to Mac-1, M25 (25-100 microM) inhibited leukocyte adhesion to fibrinogen, vitronectin, and cytokine-stimulated endothelial cells. M25 also blocked the association of uPAR with beta(1)-integrins and impaired beta(1)-integrin-dependent spreading and migration of human vascular smooth muscle cells on fibronectin and collagen. These observations indicate that uPAR associates with integrins directly and that disruption of this association broadly impairs integrin function, suggesting a novel strategy for regulation of integrins in the settings of inflammation and tumor progression.

Amino Acid Sequence↗
PubMed2000

Role for cathepsin F in invariant chain processing and major histocompatibility complex class II peptide loading by macrophages.

The major histocompatibility complex (MHC) class II-associated invariant chain (Ii) regulates intracellular trafficking and peptide loading of MHC class II molecules. Such loading occurs after endosomal degradation of the invariant chain to a approximately 3-kD peptide termed CLIP (class II-associated invariant chain peptide). Cathepsins L and S have both been implicated in degradation of Ii to CLIP in thymus and peripheral lymphoid organs, respectively. However, macrophages from mice deficient in both cathepsins S and L can process Ii and load peptides onto MHC class II dimers normally. Both processes are blocked by a cysteine protease inhibitor, indicating the involvement of an additional Ii-processing enzyme(s). Comparison of cysteine proteases expressed by macrophages with those found in splenocytes and dendritic cells revealed two enzymes expressed exclusively in macrophages, cathepsins Z and F. Recombinant cathepsin Z did not generate CLIP from Ii-MHC class II complexes, whereas cathepsin F was as efficient as cathepsin S in CLIP generation. Inhibition of cathepsin F activity and MHC class II peptide loading by macrophages exhibited similar specificity and activity profiles. These experiments show that cathepsin F, in a subset of antigen presenting cells (APCs), can efficiently degrade Ii. Different APCs can thus use distinct proteases to mediate MHC class II maturation and peptide loading.

Animals↗
PubMed2000

Early endosomal maturation of MHC class II molecules independently of cysteine proteases and H-2DM.

Major histocompatibility complex (MHC) class II molecules bind and present to CD4(+) T cells peptides derived from endocytosed antigens. Class II molecules associate in the endoplasmic reticulum with invariant chain (Ii), which (i) mediates the delivery of the class II-Ii complexes into the endocytic compartments where the antigenic peptides are generated; and (ii) blocks the peptide-binding site of the class II molecules until they reach their destination. Once there, Ii must be removed to allow peptide binding. The bulk of Ii-class II complexes reach late endocytic compartments where Ii is eliminated in a reaction in which the cysteine protease cathepsin S and the accessory molecule H-2DM play an essential role. Here, we here show that Ii is also eliminated in early endosomal compartments without the intervention of cysteine proteases or H-2DM. The Ii-free class II molecules generated by this alternative mechanism first bind high molecular weight polypeptides and then mature into peptide-loaded complexes.

Animals↗
PubMed2000

Cathepsins and compartmentalization in antigen presentation.

Intracellular trafficking and cell surface expression of MHC class II molecules is a tightly regulated process and is to a large extent, determined by the fate of the class II chaperone, the invariant chain. Inhibition of endosomal proteases critical to invariant chain proteolysis reveals marked shunting of class II complexes to lysosomal compartments. Regulation of endosomal protease activity by expression of cystatin C directs class II cell surface expression during maturation of dendritic cells. These studies highlight the taut interactions between class-II-invariant-chain complexes and endosomal proteases during MHC class II maturation.

Antigen Presentation↗
PubMed2000

Gender-related differences in severe, early-onset chronic obstructive pulmonary disease.

Men have higher prevalence rates of chronic obstructive pulmonary disease (COPD) than women, which has been attributed to the historically higher rates of cigarette smoking in males. However, the increased rates of cigarette smoking in females within the last several decades have been associated with steadily increasing rates of COPD in women. As part of a study of the genetics of severe, early-onset COPD, we assembled a group of 84 probands with severe, early-onset COPD (without severe alpha(1)-antitrypsin deficiency) and 348 of their first-degree relatives. We found a markedly elevated prevalence (71.4%) of females among the early-onset COPD probands. Among the entire group of first-degree relatives of early-onset COPD probands, univariate analysis demonstrated similar spirometric values and bronchodilator responsiveness in males and females; however, among current or ex-smokers, female first-degree relatives had significantly lower FEV(1)/ FVC (81.4 +/- 17.2% in females versus 87.0 +/- 12.9% in males, p = 0.009) and significantly greater bronchodilator responsiveness (expressed as percentage of baseline FEV(1)) (7.7 +/- 9.4% pred in females versus 4.1 +/- 6.4% pred in males, p = 0.002). Female smoking first-degree relatives were significantly more likely to demonstrate profound reductions in FEV(1) (< 40% pred) than male smoking first-degree relatives (p = 0. 03). Multivariate analysis, performed with generalized estimating equations, demonstrated that current or ex-smoking female first-degree relatives had significantly greater risk of FEV(1) < 80% pred (OR 1.91, 95% CI 1.03- 3.54), FEV(1) < 40% pred (OR 3.56, 95% CI 1.08-11.71), and bronchodilator response greater than 10% of baseline FEV(1) (OR 4.74, 95% CI 1.91-11.75). These results suggest that women may be more susceptible to the development of severe COPD.

Adult↗
PubMed2000

Nonproteolytic role for the urokinase receptor in cellular migration in vivo.

The urokinase receptor (uPAR) binds and localizes urokinase activity at cellular surfaces, facilitating fibrinolysis and cellular migration at sites of tissue injury. uPAR also participates in cellular signaling and regulates integrin-dependent adhesion and migration in vitro. We now report evidence that uPAR occupancy regulates cellular migration in vivo in the absence of functional urokinase. Recombinant murine KC (1.5 microg), a potent neutrophil chemoattractant, was delivered to the lungs of wild-type, urokinase-deficient or uPAR-deficient mice 18 h after intraperitoneal injection of 200 microg human immunoglobulin G (IgG) or a fusion protein composed of an amino-terminal receptor-binding fragment of urokinase and a human IgG Fc fragment (GFD-Fc). Whole lung lavage for recovery of leukocytes was performed 4 h later. KC treatment resulted in a 100-fold increase in lavage neutrophils. GFD-Fc injection resulted in >50% reduction in neutrophil influx in both wild-type and urokinase-deficient animals but had no effect on uPAR -/- mice. A concomitant reduction in alveolar protein leakage but no change in numbers of circulating neutrophils accompanied this attenuated inflammatory response. The reduction in neutrophil influx induced by GFD-Fc is thus related to uPAR occupancy and yet not due to disruption of uPAR-mediated proteolysis. These observations verify that protease-independent functions of uPAR operate in vivo and identify uPAR as a potential target for regulation of inflammatory processes characterized by neutrophil-mediated injury.

Administration, Intranasal↗
PubMed2000

Inducible targeting of IL-13 to the adult lung causes matrix metalloproteinase- and cathepsin-dependent emphysema.

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop significant COPD, and patients with asthma or asthma-like airway hyperresponsiveness or eosinophilia experience accelerated loss of lung function after cigarette smoke exposure. Pulmonary inflammation is a characteristic feature of lungs from patients with COPD. Surprisingly, the mediators of this inflammation and their contributions to the pathogenesis and varied natural history of COPD are not well defined. Here we show that IL-13, a critical cytokine in asthma, causes emphysema with enhanced lung volumes and compliance, mucus metaplasia, and inflammation, when inducibly overexpressed in the adult murine lung. MMP-2, -9, -12, -13, and -14 and cathepsins B, S, L, H, and K were induced by IL-13 in this setting. In addition, treatment with MMP or cysteine proteinase antagonists significantly decreased the emphysema and inflammation, but not the mucus in these animals. These studies demonstrate that IL-13 is a potent stimulator of MMP and cathepsin-based proteolytic pathways in the lung. They also demonstrate that IL-13 causes emphysema via a MMP- and cathepsin-dependent mechanism(s) and highlight common mechanisms that may underlie COPD and asthma.

Animals↗
PubMed1999

Cathepsin S controls the trafficking and maturation of MHC class II molecules in dendritic cells.

Before a class II molecule can be loaded with antigenic material and reach the surface to engage CD4+ T cells, its chaperone, the class II-associated invariant chain (Ii), is degraded in a stepwise fashion by proteases in endocytic compartments. We have dissected the role of cathepsin S (CatS) in the trafficking and maturation of class II molecules by combining the use of dendritic cells (DC) from CatS(-/-) mice with a new active site-directed probe for direct visualization of active CatS. Our data demonstrate that CatS is active along the entire endocytic route, and that cleavage of the lysosomal sorting signal of Ii by CatS can occur there in mature DC. Genetic disruption of CatS dramatically reduces the flow of class II molecules to the cell surface. In CatS(-/-) DC, the bulk of major histocompatibility complex (MHC) class II molecules is retained in late endocytic compartments, although paradoxically, surface expression of class II is largely unaffected. The greatly diminished but continuous flow of class II molecules to the cell surface, in conjunction with their long half-life, can account for the latter observation. We conclude that in DC, CatS is a major determinant in the regulation of intracellular trafficking of MHC class II molecules.

Animals↗