Eosinophil β1 integrin activation state correlates with asthma activity in a blind study of inhaled corticosteroid withdrawal

Johansson, Mats W.; Barthel, Steven R.; Swenson, Cheri A.; Evans, Michael D.; Jarjour, Nizar N.; Mosher, Deane F.; Busse, William W.

doi:10.1016/j.jaci.2006.02.032

Cited by 23 publications

(47 citation statements)

References 9 publications

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“…A scenario in which ␣4␤1 on circulating EOS is primarily responsible for arrest on VCAM-1 and extravasation into lung is supported by the findings that ␣4␤1 activation state on EOS in blood, as assessed by reactivity with the activation-sensitive anti-␤1 mAb N29, varies in asthmatic patients, and correlates with decreased lung function in an inhaled corticosteroid withdrawal study and with a measurement of airway inflammation (exhaled nitric oxide) after steroid withdrawal (88). We propose that activation of ␣M␤2 in response to IL-5 is important in subsequent phases in recruitment of already arrested EOS, possibly for de-adhesion from VCAM-1 to allow transmigration, and for transmigration itself through endothelium and tissue through interaction with various extracellular matrix ligands (77).…”

Section: Discussionmentioning

confidence: 93%

Differential Engagement of Modules 1 and 4 of Vascular Cell Adhesion Molecule-1 (CD106) by Integrins α4β1 (CD49d/29) and αMβ2 (CD11b/18) of Eosinophils

Barthel

Annis

Mosher

et al. 2006

Journal of Biological Chemistry

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We have studied adhesion of eosinophils to various forms of vascular cell adhesion molecule 1 (VCAM-1, CD106), an integrin counter-receptor implicated in eosinophil recruitment to the airway in asthma. Full-length 7d-VCAM-1, with seven immunoglobulin-like modules, contains integrin-binding sites in modules 1 and 4. The alternatively spliced six-module protein, 6d-VCAM-1, lacks module 4. In static assays, unactivated purified human blood eosinophils adhered similarly to recombinant soluble human 6d-VCAM-1 and 7d-VCAM-1 coated onto polystyrene microtiter wells. Further experiments, however, revealed differences in recognition of modules 1 and 4. Antibody blocking indicated that eosinophil adhesion to 6d-VCAM-1 or a VCAM-1 construct containing only modules 1-3, 1-3VCAM-1, is mediated by ␣4␤1 (CD49d/29) ,whereas adhesion to a construct containing modules 4 -7, 4 -7VCAM-1, is mediated by both ␣4␤1 and ␣M␤2 (CD11b/18). Inhibitors of phosphoinositide 3-kinase, which block adhesion of eosinophils mediated by ␣M␤2, blocked adhesion to 4 -7VCAM-1 but had no effect on adhesion to 6d-VCAM-1. Consistent with the antibody and pharmacological blocking experiments, eosinophilic leukemic cell lines lacking ␣M␤2 did not adhere to 4 -7VCAM-1 but did adhere to 6d-VCAM-1 or 1-3VCAM-1. Activation of eosinophils by interleukin (IL)-5 enhanced static adhesion to 6d-VCAM-1, 7d-VCAM-1, or 4 -7VCAM-1; IL-5-enhanced adhesion to all 3 constructs was blocked by anti-␣M␤2. Adhesion of unstimulated eosinophils to 7d-VCAM-1 under flow conditions was inhibited by anti-␣4 or anti-␣M. IL-5 treatment decreased eosinophil adhesion to 7d-VCAM-1 under flow, and anti-␣M had the paradoxical effect of increasing adhesion. These results demonstrate that ␣M␤2 modulates ␣4␤1-mediated eosinophil adhesion to VCAM-1 under both static and flow conditions. Vascular cell adhesion molecule 1 (VCAM-1)2 is a multimodular cell-surface glycoprotein up-regulated on human endothelium in response to pro-inflammatory cytokines in the asthmatic lung (1) and has been implicated in recruitment of eosinophils (EOS) from blood to the airway in asthma (2). Heterodimeric integrin receptors interacting with VCAM-1 are important in the rolling, firm adhesion, and movement of EOS (3, 4). These events are regulated by cytokines, which may alter integrin adhesive activity (5, 6). EOS express at least three potential integrin receptors that may be involved in adhesion to VCAM-1: ␣4␤1 (7-9), ␣D␤2 (7), and ␣4␤7 (8 -11).Considerable information is available about features of human VCAM-1 that are important for adhesion. The loop between ␤ strands C and D in the first immunoglobulin (Ig)-like module is accessible on the protein surface and contains the core integrin-recognition sequence Ile 39 -Asp-Ser-Pro-Leu 43 (IDSPL) (11-15). A second IDSPL site is present in the CD loop in module 4 (12, 14). Based on topology of exons within the mammalian genome and the similarity in amino acid sequence, a three-module unit was likely duplicated to generate VCAM-1 modules 1-3 and 4 -6 (16, 17). Modul...

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Section: Discussionmentioning

confidence: 93%

Differential Engagement of Modules 1 and 4 of Vascular Cell Adhesion Molecule-1 (CD106) by Integrins α4β1 (CD49d/29) and αMβ2 (CD11b/18) of Eosinophils

Barthel

Annis

Mosher

et al. 2006

Journal of Biological Chemistry

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“…Because purification of blood eosinophils has been found to cause the activation of ␤ 1 (35), flow cytometry was done on unfractionated blood and BAL cells. Surface expressions of ␣ M , ␣ L , ␣ X , ␣ D , ␣ 4 , ␣ 6 , ␤ 1 , ␤ 2 , ␤ 7 , activated ␤ 1 , and activated ␤ 2 were determined.…”

Section: Flow Cytometry Of Blood and Bal Cell Samplesmentioning

confidence: 99%

“…Data were analyzed using CellQuest and Flow Jo (Tree Star). Eosinophils were gated based both on scattering (high side scatter) and lack of staining with anti-CD14 and anti-CD16 (30,35). Thus, the cells that were analyzed for the PE signal fit two criteria for eosinophils by being gated inside both characteristic regions in a plot of side scatter vs FITC staining and a plot of side vs forward scatter.…”

Section: Flow Cytometry Of Blood and Bal Cell Samplesmentioning

confidence: 99%

Up-Regulation and Activation of Eosinophil Integrins in Blood and Airway after Segmental Lung Antigen Challenge

Johansson¹,

Kelly

Busse

et al. 2008

The Journal of Immunology

117

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We hypothesized that there are clinically relevant differences in eosinophil integrin expression and activation in patients with asthma. To evaluate this, surface densities and activation states of integrins on eosinophils in blood and bronchoalveolar lavage (BAL) of 19 asthmatic subjects were studied before and 48 h after segmental Ag challenge. At 48 h, there was increased expression of αD and the N29 epitope of activated β1 integrins on blood eosinophils and of αM, β2, and the mAb24 epitope of activated β2 integrins on airway eosinophils. Changes correlated with the late-phase fall in forced expiratory volume in 1 s (FEV1) after whole-lung inhalation of the Ag that was subsequently used in segmental challenge and were greater in subjects defined as dual responders. Increased surface densities of αM and β2 and activation of β2 on airway eosinophils correlated with the concentration of IL-5 in BAL fluid. Activation of β1 and β2 on airway eosinophils correlated with eosinophil percentage in BAL. Thus, eosinophils respond to an allergic stimulus by activation of integrins in a sequence that likely promotes eosinophilic inflammation of the airway. Before challenge, β1 and β2 integrins of circulating eosinophils are in low-activation conformations and αDβ2 surface expression is low. After Ag challenge, circulating eosinophils adopt a phenotype with activated β1 integrins and up-regulated αDβ2, changes that are predicted to facilitate eosinophil arrest on VCAM-1 in bronchial vessels. Finally, eosinophils present in IL-5-rich airway fluid have a hyperadhesive phenotype associated with increased surface expression of αMβ2 and activation of β2 integrins.

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“…In some cases, thapsigargin (100 nM) was added during the last 10 min of the incubation to inhibit sarco/endoplasmic reticulum Ca 2ϩ ATPases. thereby depleting intracellular Ca 2ϩ stores (9,26). Cells were washed once with incubation buffer containing EGTA.…”

Section: Depletion Of Intracellular-free Ca 2ϩmentioning

confidence: 99%

“…Both changes in conformation (affinity) as well as in clustering (valency) contribute to ␣ 4 ␤ 1 integrin activity (7,8). Recently, it was shown that an Ab recognizing activated ␤ 1 integrins on peripheral blood eosinophils correlated with disease severity in asthma (9). An important characteristic of ␣ 4 integrins (␣ 4 ␤ 1 and ␣ 4 ␤ 7 ) on lymphocytes, monocytes, as well as on eosinophils, is that they can pre-exist as adhesion receptors with an intermediate ligand-binding capacity, without the apparent need for cellular activation (10 -13).…”

mentioning

confidence: 99%

Homeostatic Intracellular-Free Ca2+ Is Permissive for Rap1-Mediated Constitutive Activation of α4 Integrins on Eosinophils

Ulfman¹,

Kamp²,

Aalst³

et al. 2008

The Journal of Immunology

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Although much progress has been made in understanding the molecular mechanisms underlying agonist-induced “inside-out” activation of integrins, little is known about how basal levels of integrin function are maintained. This is particularly important for nonactivated eosinophils, where intermediate activation of α4β1 integrin supports recruitment to endothelial cells under flow conditions. Depletion of intracellular Ca2+ and pharmacological inhibition of phospholipase C (but not other intracellular signaling molecules, including PI3K, ERK1/2, p38 MAPK, and tyrosine kinase activity) abrogated basal α4 integrin activity in nonactivated eosinophils. Basal α4 integrin activation was associated with activation of the small GTPase Rap1, a known regulator of agonist-induced integrin function. Basal Rap activation was dependent upon phospholipase C, but not intracellular Ca2+. However, depletion of intracellular Ca2+ in CD34+ hematopoietic progenitor cells abolished RapV12-mediated induction of α4 integrin activity. Thus, residual Rap activity or constitutively active Rap activity in Ca2+-depleted cells is not sufficient to induce α4 integrin activation. These data suggest that activation of functional α4 integrin activity in resting eosinophils is mediated by Rap1 provided that the intracellular-free Ca2+ is at a normal homeostatic concentration.

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Eosinophil β1 integrin activation state correlates with asthma activity in a blind study of inhaled corticosteroid withdrawal

Cited by 23 publications

References 9 publications

Differential Engagement of Modules 1 and 4 of Vascular Cell Adhesion Molecule-1 (CD106) by Integrins α4β1 (CD49d/29) and αMβ2 (CD11b/18) of Eosinophils

Differential Engagement of Modules 1 and 4 of Vascular Cell Adhesion Molecule-1 (CD106) by Integrins α4β1 (CD49d/29) and αMβ2 (CD11b/18) of Eosinophils

Up-Regulation and Activation of Eosinophil Integrins in Blood and Airway after Segmental Lung Antigen Challenge

Homeostatic Intracellular-Free Ca2+ Is Permissive for Rap1-Mediated Constitutive Activation of α4 Integrins on Eosinophils

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