Red blood cells from patients with sickle cell disease exhibit an increased adherence to cultured endothelium pretreated with tumour necrosis factor (TNF)

136

184

The possible role of physiologic stress hormones in enhancing adhesion of sickle erythrocytes (SS RBCs) to endothelial cells (ECs) in sickle cell disease (SCD) has not been previously explored. We have now found that up-regulation of intracellular cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) by epinephrine significantly increased sickle but not normal erythrocyte adhesion to both primary and immortalized ECs. Inhibition of serine/threonine phosphatases also enhanced sickle erythrocyte adhesion at least partially through a PKA-dependent mechanism. Adhesion was mediated through LW (intercellular adhesion molecule-4 [ICAM-4], CD242) blood group glycoprotein, and immunoprecipitation studies showed that LW on sickle but not on normal erythrocytes undergoes increased PKA-dependent serine phosphorylation as a result of activation. The major counter receptor for LW was identified as the ␣v␤3 integrin on ECs. These data suggest that adrenergic hormones such as epinephrine may initiate or exacerbate vaso-occlusion and thus contribute to the association of vasoocclusive events with physiologic stress. IntroductionIn sickle cell disease (SCD), abnormal adherence of sickle erythrocytes (SS RBCs) to endothelial cells (ECs) has been postulated to be important in the initiation and/or progression of vaso-occlusive crises. [1][2][3] Although many vaso-occlusive episodes are associated with intercurrent illnesses, and thus with release of endotheliumactivating cytokines such as tumor necrosis factor ␣ (TNF-␣), other vaso-occlusive episodes are associated with other types of stressors. We are interested in exploring whether physiologic stress may precipitate vaso-occlusion via activation of red cell adhesion.Human erythrocytes are equipped with a diversity of receptors and effectors that are known to mediate well-characterized signal transduction pathways in nonerythroid cells. 4 Although activation of adhesion receptors via signal transduction is well accepted in nonerythroid cells, until recently, little attention had been paid to the possibility that abnormal SS RBC adhesion might be mediated via signaling mechanisms inducing activation of RBC adhesion receptors. 5,6 Nevertheless, such events could promote, or even initiate, vaso-occlusion.A variety of stimuli, including epinephrine, have been shown to activate the basal cell adhesion molecule-Lutheran (B-CAM/LU) laminin receptor on SS RBCs through a cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) pathway. 7 Epinephrine is a major stress mediator that elevates cAMP in SS RBCs through stimulation of adrenergic receptors. 7 Cyclic AMP mediates at least some of its effects through activation of PKA. Based on these observations, we postulated that activation of SS RBC adhesion via known signaling pathways might lead to upregulation of SS RBC adhesion to endothelium, even in the absence of plasma bridging proteins. Study of up-regulation of cAMPdependent PKA signaling pathway by epinephrine in SS RBCs has now led to the identificatio...

Section: Endothelial Cellsmentioning

confidence: 99%

Epinephrine acts through erythroid signaling pathways to activate sickle cell adhesion to endothelium via LW-αvβ3 interactions

Zennadi

Hines

Castro

et al. 2004

136

184

“…Human umbilical vein endothelial cells (HUVECs) were as described. 31 K562 cells transfected with ␣ L ␤ 2 (KL/4) or ␣ 4 (KA4C6, which expresses a constitutively active form of ␣ 4 ␤ 1 ) were as described. 32 All cells were maintained in Iscoves modified Eagle medium (IMEM), 10% fetal bovine serum.…”

Section: Mammalian Cell Lines Studiedmentioning

confidence: 99%

Intercellular adhesion molecule-4 binds α4β1 and αV-family integrins through novel integrin-binding mechanisms

Spring

Parsons

Ortlepp

et al. 2001

The LW blood group glycoprotein, ICAM-4, is a member of the intercellular adhesion molecule (ICAM) family expressed in erythroid cells. To begin to address the function of this molecule, ligands for ICAM-4 on hemopoietic and nonhemopoietic cell lines were identified. Peptide inhibition studies suggest that adhesion of cell lines to an ICAM-4-Fc construct is mediated by an LDV-inhibitable integrin on hemopoietic cells and an RGD-inhibitable integrin on nonhemopoietic cells. Antibody inhibition studies identified the hemopoietic integrin as ␣ 4 ␤ 1. Antibody inhibition studies on ␣ 4 ␤ 1 -negative, nonhemopoietic cell lines suggested that adhesion of these cells is mediated by ␣ V integrins (notably ␣ V ␤ 1 and ␣ V ␤ 5 ). The structure of ICAM-4 modeled on the crystal structure of ICAM-2 was used to identify surfaceexposed amino acid residues for sitedirected mutagenesis. Neither an unusual LETS nor an LDV motif in the first domain of ICAM-4 was critical for integrin binding. ICAM-4 is the first ICAM family member shown to be a ligand for integrins other than those of the ␤ 2 family, and the data suggest that ICAM-4 has a novel integrin-binding site(s). These findings suggest a role for ICAM-4 in normal erythropoiesis and may also be relevant to the adhesive interactions of sickle cells. ( IntroductionKnowledge of cell-cell and cell-extracellular matrix interactions in bone marrow is essential for an understanding of the formation of blood cells and their migration into the peripheral circulation. Such interactions are also relevant to the biology of diseases like sickle cell disease and malaria where adhesive interactions involving red cells and damaged endothelium are crucial features of the pathology. [1][2][3] These adhesive interactions frequently involve molecules belonging to the immunoglobulin superfamily (IgSF) of proteins and the family of proteins known as integrins. Integrins are heterodimers composed of 2 noncovalently associated transmembrane subunits denoted "␣" and "␤." Eight different ␤ subunits combine in a restricted manner with 18 ␣ subunits to form some 22 different integrins. Beta subunits complex with several different ␣ subunits, while most ␣ subunits (with the exception of ␣ V , ␣ 4 , and ␣ 6 ) combine with only one ␤ subunit. 4 The LW blood group glycoprotein, or ICAM-4, is a member of the IgSF subfamily known as intercellular adhesion molecules (ICAMs). It has 2 predicted IgSF I-set domains, [5][6][7] and within the subfamily it is most similar to ICAM-2. ICAM-4 has been found expressed only on erythroid cells and weakly in placenta. 8,9 ICAM-1, -2, and -3 function in inflammation and immune responses, 10 but no function for ICAM-4 has been defined.The ICAMs are ligands for ␤ 2 integrins, and all family members, including ICAM-4, are reported to bind ␣ L ␤ 2 . [10][11][12][13] ICAM-1 and ICAM-4 are also ligands for ␣ M ␤ 2 , 10,11 while the preferred ligand for ICAM-3 is ␣ D ␤ 2 . 14 Unlike ICAM-1, -2, -3, -5, which have the ␣ L ␤ 2 -binding motif (L/I)ET(P/S)L (Figure 1), ICAM-4 has th...

“…12 Further, elevated blood levels of inflammatory and anti-inflammatory cytokines (ie, interleukin 1 ␤ [IL-1␤], IL-4, IL-6, tumor necrosis factor ␣ [TNF␣]), increased adhesion molecule expression (ie, intercellular adhesion molecule [ICAM], vascular cell adhesion molecule [VCAM], integrins, and P-selectin), and increased inflammatory biomarkers such as Creactive protein and isoprostanes have been described and appear to contribute to the development of chronic organ injury. 6,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Gene expression signatures have been used successfully to characterize tumor phenotype and to predict disease recurrence and mortality in B-cell lymphoma and breast cancer. 29,30 This comprehensive analysis of transcription profiles provides a novel means to enhance knowledge of the pathogenesis and treatment of different diseases.…”

Section: Introductionmentioning

confidence: 99%

Blood mononuclear cell gene expression profiles characterize the oxidant, hemolytic, and inflammatory stress of sickle cell disease

Jison

Munson²,

Barb³

et al. 2004

201

149

In sickle cell disease, deoxygenation of intra-erythrocytic hemoglobin S leads to hemoglobin polymerization, erythrocyte rigidity, hemolysis, and microvascular occlusion. Ischemia-reperfusion injury, plasma hemoglobin-mediated nitric oxide consumption, and free radical generation activate systemic inflammatory responses. To characterize the role of circulating leukocytes in sickle cell pathogenesis we performed global transcriptional analysis of blood mononuclear cells from 27 patients in steady-state sickle cell disease (