Interleukin-3 promotes expansion of hemopoietic-derived CD45+ angiogenic cells and their arterial commitment via STAT5 activation

Abstract

IntroductionIn the past, it has been assumed that new blood vessels originate from sprouting cells and cooption of neighboring preexisting vessels. 1 It has recently been proposed, however, that both vascular healing and tumor angiogenesis are also supported by mobilization and recruitment of other cells, including the bone marrow (BM)-derived cells denoted as endothelial progenitor cells (EPCs). 2,3 The existence of a BM reservoir of EPCs has attracted interest, especially as target for therapeutic intervention, both in chronic inflammatory diseases and cancer. However, a consensus on the identity and biologic activity of EPCs is still controversial. In general, 2 types of EPCs have been described to date: early and late EPCs. 4 Although they share common features, they have distinct features with respect to morphology, proliferative potential, and in vitro functional characteristics. [5][6][7][8][9][10] Because early EPCs do not adopt a typical endothelial phenotype in vitro and enhance neovascularization in an indirect paracrine fashion in vivo, they have been redefined as circulating angiogenic cells (CAC). 4 More recently, it has been reported that CD45 ϩ CAC retain some myeloid progenitor activity and are unable to originate perfused vessels in vivo. 10 Thus, the best way to distinguish between EPCs and hemopoietic-derived CAC seems by their function rather than by their phenotype.The positive contribution of hemopoietic-derived cells in inflammatory and tumor neoangiogenesis has been extensively demonstrated. [11][12][13] The release of angiogenic mediators, including IL-3, by activated T cells has been reported to contribute to this process. [14][15][16][17][18] Early in vivo and in vitro studies have implicated interleukin (IL) in the survival, proliferation, and differentiation of hemopoietic progenitor/stem cells (HSC) as well as of mature cells. 19,20 However, a clinical study revealed that administration of IL-3 also increased BM vascularization, 21 and it has recently been demonstrated that IL-3 is involved in inflammatory and tumor angiogenesis. 22,23 IL-3 exerts its biologic effects by activating the signal transducer and activator of transcription 5 (STAT5) signaling pathway, both in hemopoietic 24 and vascular tissues 22 as revealed by the intrinsic defective IL-3 responsiveness of STAT5-deficient HSC 25 and endothelial cells (EC). 26 The 2 highly homologous proteins STAT5A and STAT5B, 27 activated by Janus tyrosine kinase 2 (JAK2) 28 or c-Src kinases, 29 act as signaling components between the plasma membrane and the nucleus, and as transcriptional factors, by regulating the expression of genes involved in different cell functions including proliferation, survival, and differentiation. 27 During development, specification of EC into arterial or venous cells represents the main determinant of vascular diversity. Physiologic parameters were considered the main factors in establishing arterial and venous identity. 30 However, more recently, it has been shown that the membrane ligand EphrinB2 and ...

Inhibition of β1 integrin and IL-3Rβ common subunit interaction hinders tumour angiogenesis

“…Consistently, data reported in Figure 3b show that these events correlated with inhibition of EPC cell-cycle progression, without affecting cell adhesion ( Figure 3c). Besides affecting EPC expansion, IL-3 also induces their arterial differentiation (Zeoli et al, 2008). Indeed, IL-3-cultured EPCs acquired arterial commitment (EphrinB1, EphrinB2 and Notch4 expression), but failed to undergo venous (negative EphB4 expression) or lymphatic (negative vascular endothelial growth factor receptor-3 (VEGFR3) and lymphatic vessel endothelial hyaluronan receptor-1 expression) specification ( Figure 3d) (Gro¨ger et al, 2004;Ma¨kinen et al, 2005).…”

“…To date, there is no conclusive data available on the role of integrins in regulating adult vasculogenic process. To address this issue, a vasculogenic assay was performed as described previously (Zeoli et al, 2008;Togliatto et al, 2010). Severe combined immune deficiency (SCID) mice were injected s.c. with Matrigel containing EPCs, IL-3 and soluble Fc1.3, Fc1.4, Fc4 or the Fc portion of human IgG, as control.…”

“…EPCs were isolated from peripheral blood mononuclear cells, recovered from eight normal subjects (five males and three females; age, 40.0±2) and cultured as described previously (Zeoli et al, 2008), in the presence or in the absence of the indicated Fc fusion proteins. In selected experiments, EPCs were also cultured with or without the indicated Fc fragments in the presence of VEGF (10 ng/ml).…”

“…In vivo vasculogenesis and angiogenesis To evaluate the in vivo vasculogenic process (Zeoli et al, 2008), SCID mice (Charles River Laboratories Italia Srl, Calco (LC), Italy) (four mice for each experimental group) were injected s.c. with growth factor-reduced Matrigel containing 50 ng/ml IL-3 and 2 Â 10 6 CSFE-labelled EPCs (CSFE, fluorescent dye carboxyfluorescein diacetate succinimidyl ester; Invitrogen Srl, San Giuliano Milanese (MI), Italy), with or without 100 mg/ml IL-3Rbc/b1 integrin complex: a novel antiangiogenetic target B Uberti et al of Fc1.3, Fc1.4 or Fc4. Fifty mg/ml of IgG-Fc fragment was used as a control.…”

“…Among the integrins involved in these processes, the a5b1 has attracted considerable interest (Silva et al, 2008). Indeed, for triggering IL-3-mediated expansion and arterial specification of both circulating and bone marrow-derived EPCs, matrix ligand occupancy of a5b1 integrins is essential (Zeoli et al, 2008). Some signalling enzymes are regulated by both integrins and growth factor/cytokine receptors, providing key nodal points at which the two system can interplay (Giancotti and Tarone, 2003).…”