PHD2 regulates arteriogenic macrophages through TIE2 signalling

• DOI: 10.1002/emmm.201302695
• Publication Date: 2013-04-25T07:40:40Z
• Authors: Alexander Hamm; Lorenzo Veschini; Yukiji Takeda; Sandra Costa; Estelle Delamarre; Mario Leonardo Sq...; Anne‐Theres Henze; Mathias Wenes; Jens Serneels; Ferdinando Pucci; Carmen Roncal; Andrey Anisimov; Kari Alitalo; Michele De Palma; Massimiliano Mazzone
• Keywords: Medicine (General); QH426-470; Ischaemia; INHIBITS TUMOR-GROWTH; Mice; Ischemia; Arteriogenesis; Ischaemia; Macrophages; PHD2; TIE2; Angiopoietin-1; Angiopoietin-2; Animals; Down-Regulation; Gene Silencing; Humans; Hypoxia-Inducible Factor-Proline Dioxygenases; Ischemia; Macrophages; Mice; Mice, Inbred BALB C; MicroRNAs; Phenotype; Procollagen-Proline Dioxygenase; Receptor, TIE-2; Signal Transduction; Non-U.S. Gov't; Inbred BALB C; IN-VIVO; Research Articles; Mice, Inbred BALB C; 0303 health sciences; Receptor, TIE-2; ISCHEMIA; macrophages; 3. Good health; TIE2; Phenotype; arteriogenesis; ischaemia; Receptor; COLLATERAL CIRCULATION; Signal Transduction; Procollagen-Proline Dioxygenase; 610; Down-Regulation; Research Support; Arteriogenesis; Hypoxia-Inducible Factor-Proline Dioxygenases; Angiopoietin-2; 03 medical and health sciences; R5-920; INFLAMMATION; Journal Article; Genetics; Angiopoietin-1; PHD2; Animals; Humans; Gene Silencing; TIE-2; Science & Technology; FEMORAL-ARTERY OCCLUSION; Macrophages; ENDOTHELIAL-CELLS; TIE2-EXPRESSING MONOCYTES; Biomedicine; MicroRNAs; ANGIOPOIETIN-2; THERAPEUTIC ANGIOGENESIS

Occlusion of the main arterial route redirects blood flow to the collateral circulation. We previously reported that macrophages genetically modified to express low levels of prolyl hydroxylase domain protein 2 (PHD2) display an arteriogenic phenotype, which promotes the formation of collateral vessels and protects the skeletal muscle from ischaemic necrosis. However, the molecular mechanisms underlying this process are unknown. Here, we demonstrate that femoral artery occlusion induces a switch in macrophage phenotype through angiopoietin-1 (ANG1)-mediated Phd2 repression. ANG blockade by a soluble trap prevented the downregulation of Phd2 expression in macrophages and their phenotypic switch, thus inhibiting collateral growth. ANG1-dependent Phd2 repression initiated a feed-forward loop mediated by the induction of the ANG receptor TIE2 in macrophages. Gene silencing and cell depletion strategies demonstrate that TIE2 induction in macrophages is required to promote their proarteriogenic functions, enabling collateral vessel formation following arterial obstruction. These results indicate an indispensable role for TIE2 in sustaining in situ programming of macrophages to a proarteriogenic, M2-like phenotype, suggesting possible new venues for the treatment of ischaemic disorders.