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Biomedical subjects

D J Erle

Publications and source records attributed to D J Erle.

At least 19 recordsLinked to original sources
PubMed2005

Tissue-selective mast cell reconstitution and differential lung gene expression in mast cell-deficient Kit(W-sh)/Kit(W-sh) sash mice.

BACKGROUND: Mast cell-deficient Kit(W)/Kit(W-v) mice are an important resource for studying mast cell functions in vivo. However, because they are compound heterozygotes in a mixed genetic background and are infertile, they cannot be crossed easily with other mice. OBJECTIVE: To overcome this limitation, we explored the use of Kit(W-sh)/Kit(W-sh) mice for studying mast cell biology in vivo. RESULTS: These mice are in a C57BL/6 background, are fertile and can be bred directly with other genetically modified mice. Ten-week-old Kit(W-sh)/Kit(W-sh) are profoundly mast cell-deficient. No mast cells are detected in any major organ, including the lung. Gene microarrays detect differential expression of just seven of 16,463 genes in lungs of Kit(W-sh)/Kit(W-sh) mice compared with wild-type mice, indicating that resting mast cells regulate expression of a small set of genes in the normal lung. Injecting 10(7) bone marrow-derived mast cells (BMMC) into tail veins of Kit(W-sh)/Kit(W-sh) mice reconstitutes mast cell populations in lung, stomach, liver, inguinal lymph nodes, and spleen, but not in the tongue, trachea or skin. Injection of BMMC into ear dermis or peritoneum reconstitutes mast cells locally in these tissues. When splenectomized Kit(W-sh)/Kit(W-sh) mice are intravenously injected with BMMC, mast cells circulate longer and are found more often in the liver and inguinal lymph nodes, indicating that the spleen acts as a reservoir for mast cells following injection and limits migration to some tissues. CONCLUSION: In summary, these findings show that mast cell-deficient Kit(W-sh)/Kit(W-sh) mice possess unique attributes that favour their use for studying mast cell functions in vivo.

Animals↗
PubMed2001

Preferential production of interferon-gamma by CD4+ T cells expressing the homing receptor integrin alpha4/beta7.

Recent studies indicate that T helper type 1 (Th1) and 2 (Th2) lymphocytes differ in their expression of molecules that control T-cell migration, including adhesion molecules and chemokine receptors. We investigated the relationship between cytokine production and expression of the homing receptor integrin alpha4/beta7 on T cells. We began by analysing cytokine production by human CD4+ CD45RA- memory/effector T cells following brief (4 hr) stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. alpha4/ beta7high CD4+ T cells were more likely to produce the Th1 cytokine interferon-gamma (IFN-gamma) than were alpha4/beta7- CD4+ T cells in all six subjects studied. In contrast, production of the Th2 cytokine interleukin-4 (IL-4) was similar on alpha4/ beta7high and alpha4/beta7- CD4+ T cells. In addition, we found that human CD4+ CD45RA- T cells that adhered to the alpha4/beta7 ligand mucosal addressin cell adhesion molecule-1 (MAdCAM-1) had a greater capacity to produce IFN-gamma than did non-adherent cells, suggesting that the association between alpha4/beta7 expression and IFN-gamma production has functional significance. These results suggested that primary activation under Th1-promoting conditions might favour expression of alpha4/beta7. We directly examined this possibility, and found that naïve murine CD4+ T cells activated under Th1-promoting conditions expressed higher levels of alpha4/beta7 compared to cells activated under Th2-promoting conditions. The association between alpha4/beta7 expression and IFN-gamma production by CD4+ T cells may help to determine the cytokine balance when MAdCAM-1 is expressed at sites of inflammation in the intestine or elsewhere.

Adult↗
PubMed2001

Interleukin-13 induces dramatically different transcriptional programs in three human airway cell types.

Interleukin (IL)-13, a cytokine released by T lymphocytes during immediate hypersensitivity responses, is a central mediator of asthma. Because IL-13 induces phenotypic features of asthma in mice deficient in T and B lymphocytes, it is likely that this cytokine contributes to the development of asthma by acting directly on resident airway cells. To analyze the global effects of IL-13 on gene expression in airway cells that could contribute to the phenotypic features of asthma, we used Genechip HuGene FL arrays (Affymetrix, Santa Clara, CA) that contain probes for approximately 6,500 human genes. Despite activating a common signaling pathway, IL-13 induced dramatically different patterns of gene expression in primary cultures of airway epithelial cells, airway smooth muscle cells, and lung fibroblasts, with little overlap among cell types. The most prominent effects of IL-13 were on airway smooth muscle, but several genes induced in airway epithelial cells and fibroblasts are also candidates that may contribute to phenotypic features of asthma. These results suggest that the in vivo response to IL-13 in the airways likely results from a combination of distinct effects on each of several resident airway cell types.

Cells, Cultured↗
PubMed2000

Effect of serial-day exposure to nitrogen dioxide on airway and blood leukocytes and lymphocyte subsets.

Nitrogen dioxide (NO2) is a free radical-producing oxidant gas. Inhalation of NO2 could cause airway inflammation, and decrease immune function. This experiment tested the hypothesis that exposure to NO2 would: 1) increase leukocytes in bronchoalveolar lavage (BAL); and 2) change the distribution of lymphocyte subsets and activation in BAL and peripheral blood (PB). Using a counter-balanced, repeated-measures design, 15 healthy volunteers were exposed to filtered air (FA) or 2.0 parts per million NO2 for 4 h x day(-1) (4 x 30 min of exercise), for three consecutive days. Bronchoscopy was performed 18 h following each exposure set, and PB was drawn pre-exposure and pre-bronchoscopy. Flow cytometry was used to enumerate lymphocyte subsets and activation makers in BAL and PB. In the bronchial fraction, there was an increase in the percentage of neutrophils following NO2 exposure compared to FA (median (interquartile range): 10.6 (4.8-17.2)% versus 5.3 (2.5-8.3)%; p=0.005). In the BAL, there was a decrease in the percentage of T-helper cells following NO2 exposure compared to FA (55.9 (40.8-62.7)% versus 61.6 (52.6-65.2)%; p=0.022). For PB, there were no between-condition differences in any leukocyte or lymphocyte subsets, or activation. In conclusion exposure to nitrogen dioxide results in bronchial inflammation and a minimal change in bronchoalveolar lavage T-helper cells, and no changes in peripheral blood cells.

Adult↗
PubMed1998

Secondary lymphoid-tissue chemokine (SLC) stimulates integrin alpha 4 beta 7-mediated adhesion of lymphocytes to mucosal addressin cell adhesion molecule-1 (MAdCAM-1) under flow.

The attachment of leukocytes to the endothelium is a multistep process that depends upon a very rapid increase in the adhesive activity of leukocyte integrins. A pertussis toxin-sensitive pathway stimulates integrin-dependent lymphocyte adhesion to Peyer's patch high endothelial venules in vivo, but the factors responsible for activating this pathway have not been identified previously. We now report that secondary lymphoid-tissue chemokine (SLC) (also known as 6Ckine, Exodus-2, and thymus-derived chemotactic agent 4), a recently described CC chemokine that is expressed in Peyer's patches and lymph nodes, rapidly activates integrin-mediated lymphocyte adhesion. Immobilized SLC increased the adhesion of HUT-78 T cells and human PBLs to mucosal addressin cell adhesion molecule-1, a protein that is expressed on Peyer's patch and mesenteric lymph node high endothelial venules. This effect of SLC was seen in both static and flow chamber adhesion assays, was mediated by integrin alpha 4 beta 7, and was inhibited by pertussis toxin. The other CC chemokines tested did not increase adhesion to mucosal addressin cell adhesion molecule-1. SLC had a greater effect on naive CD4+ T cells than on memory CD4+ T cells; CD8+ T cells, B cells, and NK cells were also responsive to SLC. SLC is likely to play an important role in regulating the recruitment of lymphocytes to Peyer's patches and lymph nodes.

Cell Adhesion↗
PubMed1998

Integrin beta cytoplasmic domains differentially bind to cytoskeletal proteins.

Integrin cytoplasmic domains connect these receptors to the cytoskeleton. Furthermore, integrin-cytoskeletal interactions involve ligand binding (occupancy) to the integrin extracellular domain and clustering of the integrin. To construct mimics of the cytoplasmic face of an occupied and clustered integrin, we fused the cytoplasmic domains of integrin beta subunits to an N-terminal sequence containing four heptad repeat sequences. The heptad repeats form coiled coil dimers in which the cytoplasmic domains are parallel dimerized and held in an appropriate vertical stagger. In these mimics we found 1) that both conformation and protein binding properties are altered by insertion of Gly spacers C-terminal to the heptad repeat sequences; 2) that the cytoskeletal proteins talin and filamin are among the polypeptides that bind to the integrin beta1A tail. Filamin, but not talin binding, is enhanced by the insertion of Gly spacers; 3) binding of both cytoskeletal proteins to beta1A is direct and specific, since it occurs with purified talin and filamin and is inhibited in a point mutant (beta1A(Y788A)) or in splice variants (beta1B, beta1C) known to disrupt cytoskeletal associations of beta1 integrins; 4) that the muscle-specific splice variant, beta1D, binds talin more tightly than beta1A and is therefore predicted to form more stable cytoskeletal associations; and 5) that the beta7 cytoplasmic domain binds filamin better than beta1A. The structural specificity of these associations suggests that these mimics offer a useful approach for the analysis of the interactions and structure of the integrin cytoplasmic face.

Amino Acid Sequence↗
PubMed1997

Presentation of integrins on leukocyte microvilli: a role for the extracellular domain in determining membrane localization.

Adhesion of blood leukocytes to the endothelium involves multiple steps including initial attachment (tethering), rolling, and firm arrest. Presentation of adhesion molecules on leukocyte microvilli can substantially enhance tethering. Localization of L-selectin to microvilli and of CD44 to the planar cell body have been shown to depend upon their transmembrane and cytoplasmic domains. We investigated the role of leukocyte integrin transmembrane and cytoplasmic domains in initiating adhesion under flow and in microvillous localization. Integrins alpha4beta7, alphaLbeta2, and alphaMbeta2 were heterologously expressed in K562 cells. alpha4beta7 initiated adhesion under flow and localized to microvilli, whereas beta2 integrins did not initiate adhesion and localized to the cell body. Chimeric integrins were produced by replacing the alpha4beta7 cytoplasmic and/or transmembrane domains with the homologous domains of alphaLbeta2 or alphaMbeta2. Unexpectedly, these chimeras efficiently mediated adhesion to the alpha4beta7 ligand mucosal addressin cell adhesion molecule-1 under flow and localized to microvilli. Therefore, differences between the transmembrane and cytoplasmic domains of alpha4 and beta2 integrins do not account for differences in ability to support attachment under flow or in membrane localization. Integrins alpha4beta1, alpha5beta1, alpha6Abeta1, alphavbeta3, and alphaEbeta7 also localized to microvilli. Transmembrane proteins known or suspected to associate with extracellular domains of microvillous integrins, including tetraspans and CD47, were concentrated on microvilli as well. These findings suggest that interactions between the extracellular domains of integrins and associated proteins could direct the assembly of multimolecular complexes on leukocyte microvilli.

Cell Adhesion↗
PubMed1997

Structure-function analysis of the integrin beta 7 subunit: identification of domains involved in adhesion to MAdCAM-1.

Beta 7 integrins serve special roles in mucosal immunity. Alpha 4 beta 7-mediated adhesion to mucosal addressin cell adhesion molecule-1 (MAdCAM-1) directs lymphocyte homing to the gut, and alpha E beta 7 mediates binding of lymphocytes to E-cadherin on epithelial cells. Since alpha 4 beta 7 mediates adhesion to MAdCAM-1 but alpha 4 beta 1 does not, we used beta 7/beta 1 chimeras to directly assess the importance of specific regions of beta 7 in MAdCAM-1 binding. We found a region of beta 7 (residues 46-386) that accounts for specificity of alpha 4 beta 7 binding to MAdCAM-1. We also used human/mouse and human/rat chimeric beta 7 subunits to map epitopes recognized by fifteen anti-beta 7 mAbs. Six of seven Abs that block adhesion to MAdCAM-1 and E-cadherin (Fib 21, 22, 27, 30, 504; Act-1) mapped to amino acid residues 176-250. Residues 176-250 lie within the region of beta 7 that specifies MAdCAM-1 binding and also within a region that has a predicted structure homologous to the metal ion-dependent adhesion site (MIDAS) domains of the integrin subunits alpha L and alpha M. Three new Abs that recognize beta 7 in the presence of Mn2+, but not Ca2+, and promote adhesion to MAdCAM-1, mapped to amino acids 46-149. One blocking and five other Abs mapped to other regions (amino acids 387-725). We conclude that a MIDAS-like domain serves a critical role in beta 7 integrin-mediated adhesion.

Animals↗
PubMed1996

Differential expression of homing molecules on recirculating lymphocytes from sheep gut, peripheral, and lung lymph.

The adhesion molecules integrin alpha 4 beta 7 and L-selectin have been hypothesized to help direct selective migration (homing) of lymphocytes to the gut and peripheral lymph nodes, respectively. An important prediction of current models is that lymphocytes selectively recirculating through an organ will preferentially express adhesion receptors for organ-specific endothelial ligands. To test this prediction, we directly examined the expression of cell adhesion molecules on lymphocytes recirculating through the gut, the periphery, and the lung. Integrin beta 7 was highly expressed on CD4+CD45R- "memory/effector" T cells recirculating through the gut (mesenteric efferent and lower thoracic duct lymph). In contrast, cells recirculating through the periphery (prescapular efferent lymph) and the lung (caudal mediastinal efferent lymph) had much less beta 7 expression. A similar pattern of organ-specific beta 7 expression was seen on B cells. Beta 7 expression corresponded with adhesion to the gut mucosal addressin, MAdCAM-1, in vitro. The peripheral lymph node homing receptor, L-selectin, was expressed at higher levels on CD4+CD45R- T cells from peripheral lymph than on cells from gut or lung lymph. These results provide additional strong support for alpha 4 beta 7 and L-selectin involvement in lymphocyte homing to the gut and to peripheral lymph nodes, respectively. Lymphocytes emigrating from the lung expressed low levels of both homing receptors and likely utilize molecules other than alpha 4 beta 7 and L-selectin for migration to the lung and associated lymphoid tissue.

Animals↗
PubMed1996

Interleukin 4, but not interleukin 5 or eosinophils, is required in a murine model of acute airway hyperreactivity.

Reversible airway hyperreactivity underlies the pathophysiology of asthma, yet the precise mediators of the response remain unclear. Human studies have correlated aberrant activation of T helper (Th) 2-like effector systems in the airways with disease. A murine model of airway hyperreactivity in response to acetylcholine was established using mice immunized with ovalbumin and challenged with aerosolized antigen. No airway hyperractivity occurred in severe combined immunodeficient mice. Identically immunized BALB/c mice developed an influx of cells, with a predominance of eosinophils and CD4+ T cells, into the lungs and bronchoalveolar lavage fluid at the time that substantial changes in airway pressure and resistance were quantitated. Challenged animals developed marked increases in Th2 cytokine production, eosinophil influx, and serum immunoglobulin E levels. Neutralization of interleukin (IL) 4 using monoclonal antibodies administered during the period of systemic immunization abrogated airway hyperractivity but had little effect on the influx of eosinophils. Administration of anti-IL-4 only during the period of the aerosol challenge did not affect the subsequent response to acetylcholine. Finally, administration of anti-IL-5 antibodies at levels that suppressed eosinophils to < 1% of recruited cells had no effect on the subsequent airway responses. BALB/c mice had significantly greater airway responses than C57BL/6 mice, consistent with enhanced IL-4 responses to antigen in BALB/c mice. Taken together, these data implicate IL-4 generated during the period of lymphocyte priming with antigen in establishing the cascade of responses required to generate airway hyperractivity to inhaled antigen. No role for IL-5 or eosinophils could be demonstrated.

Acetylcholine↗
PubMed1996

Inactivation of the integrin beta 6 subunit gene reveals a role of epithelial integrins in regulating inflammation in the lung and skin.

The integrin alpha v beta 6 is only expressed in epithelial cells. In healthy adult epithelia, this receptor is barely detectable, but expression is rapidly induced following epithelial injury. Mice homozygous for a null mutation in the gene encoding the beta 6 subunit had juvenile baldness associated with infiltration of macrophages into the skin, and accumulated activated lymphocytes around conducting airways in the lungs. Beta 6-/- mice also demonstrated airway hyperresponsiveness to acetylcholine, a hallmark feature of asthma. These results suggest that the epithelial integrin alpha v beta 6 participates in the modulation of epithelial inflammation. Genetic or acquired alterations in this integrin could thus contribute to the development of inflammatory diseases of epithelial organs, such as the lungs and skin.

Alopecia↗
PubMed1994

Expression and function of the MAdCAM-1 receptor, integrin alpha 4 beta 7, on human leukocytes.

Recirculation of mouse lymphocytes to the gut involves binding of the lymphocyte integrin alpha 4 beta 7 to the mucosal vascular addressin, MAdCAM-1. In humans, indirect evidence suggests that CD4+ T cells that express high levels of alpha 4 beta 7 migrate selectively to the gut. We now report that human adult blood CD8+ T cells and B cells, like CD4+ T cells, have heterogeneous expression of alpha 4 beta 7. In contrast, NK cells, eosinophils, and newborn blood T and B cells have relatively homogeneous expression of alpha 4 beta 7. CD4+ and CD8+ T cell expression of alpha 4 beta 7 was related to age, CD45RA expression, and integrin beta 1 (CD29) expression, suggesting that alpha 4 beta 7 expression changes after primary activation of CD4+ and CD8+ T cells in vivo. To directly determine whether human alpha 4 beta 7 mediates adhesion to MAdCAM-1, we performed in vitro adhesion assays with two alpha 4 beta 7+ human lymphoma cell lines. The results indicate that human alpha 4 beta 7 is a receptor for MAdCAM-1, whereas alpha 4 beta 1 is not. Adhesion of HUT 78 cells to MAdCAM-1 required Mn2+, whereas adhesion of RPMI 8866 cells did not, suggesting that alpha 4 beta 7 may have at least two distinct functional states. The ability of lymphocytes to bind to MAdCAM-1 and recirculate to mucosal organs is likely to be influenced both by the level of alpha 4 beta 7 expression and by the functional state of the alpha 4 beta 7 molecule.

Adult↗
PubMed1994

Lung epithelial lining fluid T cell subsets defined by distinct patterns of beta 7 and beta 1 integrin expression.

Integrins are heterodimeric cell-surface glycoproteins that mediate cell-cell and cell-matrix adhesion. We previously identified cDNA encoding a novel integrin beta subunit, beta 7, from bronchoalveolar lavage fluid (BALF) leukocytes. The beta 7 subunit protein is now known to associate with at least two integrin alpha subunits on lymphocytes. One beta 7 integrin, alpha 4 beta 7, mediates lymphocyte adhesion to endothelium and to fibronectin. The other known beta 7 integrin, alpha E beta 7, has recently been shown to mediate lymphocyte-epithelial cell adhesion in vitro. We used flow microfluorometry to analyze the expression of alpha 4 beta 7, alpha E beta 7, and other integrins on blood T cells and epithelial lining fluid T cells obtained from five healthy adult volunteers by bronchoalveolar lavage. alpha 4 beta 7 was the predominant beta 7 integrin on blood T cells, whereas alpha E beta 7 was predominant on BALF T cells. BALF T cells could be divided into alpha E beta 7- and alpha E beta 7+ subsets. Between 29 and 61% (mean 42%) of CD3+ T cells were alpha E beta 7+ alpha E beta 7 was more likely to be present on CD8+ T cells (mean 69% alpha E beta 7+) than on CD4+ T cells (mean 29% alpha E beta 7+). The alpha E beta 7- and alpha E beta 7+ BALF T cell subsets were also found to differ in their expression of other integrins.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Selective expression of integrin alpha 4 beta 7 on a subset of human CD4+ memory T cells with Hallmarks of gut-trophism.

Human memory CD4+ T lymphocytes are heterogenous in expression of integrins; one subset has the unexpected phenotype beta 1 low alpha 4 high. We demonstrate that this subset is unique among CD4+ cells in expression of high levels of alpha 4 beta 7, detected by a distinctive mAb Act-1. alpha 4 beta 7 is involved in binding to both fibronectin and vascular cell adhesion molecule-1; Act-1 blocks cell binding to the former and augments binding to the latter. Act-1 expression marks a subset of memory cells that, unlike the predominant circulating memory cell, has up-regulated beta 7 rather than beta 1. Their phenotype is distinct from that described for skin-homing T cells and is fully consistent with that described for gut-homing T cells. Differential adhesion capacity of this subset is verified by selective binding to FN and vascular cell adhesion molecule-1 in a beta 1-independent fashion. Thus, alpha 4 beta 7 detected on this subset of circulating normal T cells fits the expectations for a gut-homing receptor.

Antibodies, Monoclonal↗