Differences in Potency of CXC Chemokine Ligand 8-, CC Chemokine Ligand 11-, and C5a-Induced Modulation of Integrin Function on Human Eosinophils

Ulfman, Laurien H.; Alblas, Jacqueline; Aalst, Corneli W. van; Zwaginga, Jaap Jan; Koenderman, Leo

doi:10.4049/jimmunol.175.9.6092

Cited by 19 publications

(16 citation statements)

References 50 publications

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“…11). ␣ M ␤ 2 is believed to be important for eosinophil migration (22,51,53,(93)(94)(95). Thus, the scenario has migrating eosinophils using activated ␣ M ␤ 2 and possibly other integrins to interact with multiple substrates (22,36,92), including VCAM-1, ICAM-1, and extracellular matrix proteins, on endothelial cells, in connective tissue, and on epithelium of the bronchial wall.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…Because the GTPase Rap1 has been shown to play a role in several cases of agonist-induced integrin activation (4,20,21,36), we tested the hypothesis that Rap1 may also regulate basal ␣ 4 -integrin function in resting eosinophils. Active GTP-bound Rap1 was readily precipitated from lysates of resting eosinophils (Fig.…”

Section: Activation Of Rap1 In Resting Eosinophils Correlates With Bamentioning

confidence: 99%

“…Mononuclear cells were removed by centrifugation over isotonic Ficoll (1.077 g/ml). After lysis of erythrocytes with an isotonic icecold NH 4 Cl solution, granulocytes were washed and resuspended in isolation buffer. Eosinophils were purified from granulocytes by negative immunomagnetic selection using anti-CD16-conjugated microbeads (MACS; Miltenyi Biotec) (23) and anti-CD3 and -CD14-conjugated microbeads were additionally added to avoid mononuclear cell contamination.…”

Section: Isolation Of Eosinophilsmentioning

confidence: 99%

“…Subsequently, firm adhesion is initiated by activation of the cells through chemoattractants which signal via G protein-coupled receptors. These processes result in different states of integrin activation depending on the chemoattractant present (4). Activated integrins bind to vascular adhesion molecules of the Ig superfamily which eventually results in firm adhesion.…”

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confidence: 99%

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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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“…Since C5a can affect regulation of the ROCK pathway, surface expression of integrin and cadherin family members, and, independent from these functions, can act as a pro-survival factor (Morris et al 2011;Liu et al 2011;Strainic et al 2008;Ulfman et al 2005), we next examined whether C5a could have a similar function in hPSC. We therefore treated H9 hESC with 1nM C5a, or vehicle alone, 1 hour prior to enzymatic single cell dissociation and quantified cell survival of these single cell dissociated cultures after 16 hours.…”

Section: C5a Increases Single Cell Survival Dissociation Of Hpscs Tomentioning

confidence: 99%

Exploring the role of C5a-C5aR1 signalling in development through pluripotent stem cell modelling

Hawksworth¹

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The complement system has been traditionally described as a powerful controller of innate immunity.With activation through the recognition of pathogenic surfaces, spontaneous hydrolysis, or extrinsic cleavage, a cleavage cascade is initiated culminating in the formation of the active complement fragments C3a, C3b, C5a, and C5b. These fragments direct immune cells to sites of inflammation, as well as tagging pathogens for destruction and directly lysing foreign cells. It is now clear however, that this complex family of proteins possesses a wide range of functions outside of immune regulation. From fertilisation and morphogenesis, to the control of foetal and adult stem cell populations, studies have described novel actions of complement factors. This thesis is focussed on the central complement receptor, C5aR1. Traditionally described as a potent activating and chemotactic receptor for immune cells, C5aR1 has been shown to function in a number of nonimmune cell populations. Of note, our laboratory has previously described a role for C5aR1 in neural tube closure, with loss of C5aR1 signalling associated with increased neural tube defects under folate deficient conditions. However, a mechanistic role of C5aR1 at this stage of development was not described.In this thesis, pluripotent stem cells were utilised as an in vitro model of human development to interrogate the expression and function of C5aR1 at a number of developmental stages. Specifically, in pluripotent stem cells representative of the blastocyst inner cell mass, in neural rosettes representative of the developing ventricular zone, and in matured post-mitotic cortical neurons. This builds on previous work by our laboratory, which had identified C5aR1 actions in the mouse ventricular zone, analogous to late neural rosette cultures, and had shown a neurotoxic effect of C5aR1 in post-mitotic mouse neurons.C5aR1 was found to be expressed in pluripotent stem cells, with a role in promoting maintenance of pluripotency in the absence of FGF2 signalling. Additionally, C5aR1 was found to be apically expressed in human neural rosettes, with signalling promoting proliferation and maintenance of cell polarity. This work correlated well with mouse studies performed outside of this thesis, to show that in vivo, loss of C5aR1 in this neural progenitor population resulted in behavioural deficits and microstructural brain changes. Lastly, we determined the mRNA expression of C5aR1 in human postmitotic cortical neurons. However, in contrast to previous mouse studies, exogenous C5a, alone or in the presence of secondary stressors, had little effect on the survival of these cells.Overall, the results presented in this thesis have further expanded our knowledge of C5a-C5aR1 signalling in development, describing novel roles for this signalling pathway. The use of pluripotent stem cells allowed for the exploration of C5aR1 actions in human development that would otherwise be limited to animal models. Additionally, it allowed for the correlation of previous animal resu...

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Differences in Potency of CXC Chemokine Ligand 8-, CC Chemokine Ligand 11-, and C5a-Induced Modulation of Integrin Function on Human Eosinophils

Cited by 19 publications

References 50 publications

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

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

Exploring the role of C5a-C5aR1 signalling in development through pluripotent stem cell modelling

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