The Temporal and Spatial Distribution of Macrophage Subpopulations During Arteriogenesis

Abstract

Chronic arterial occlusion leads to growth of collaterals - a process termed arteriogenesis, in which macrophages play a prominent role in remodelling and growth. However, a detailed analysis which of distinct macrophage subpopulations involved in arteriogenesis has never been performed. In the present study the temporal and spatial distribution of macrophage subtypes during arteriogenesis in a rat model with chronically elevated fluid shear stress (FSS) is investigated. Local macrophage subpopulations were histologically immuno-phenotyped using CD68 (a ubiquitous macrophage marker) and CD163, a specific M2 macrophage marker. Without occlusion few M2-macrophages reside in the perivascular space. Early after occlusion (12h) the number of M2 macrophages increases strongly and M1 macrophages begin emerging into the collateral. After 3 days they appear in the perivascular space. Both macrophage subtypes increase until 28d after treatment, whereas M2 macrophages dominate at the site of collateral growth. The local distribution of the subpopulations changes during the arteriogenic process. Whereas M1 macrophages are detected directly adjacent to the media, M2 macrophages are present in the most outer perivascular region of the growing collateral vessel. Systemic alterations of blood leucocytes in mice after femoral artery ligature (FAL) were investigated by FACS analysis of serial blood samples. During collateral remodelling histological changes were not reflected in circulating monocytes in the peripheral blood. The activation state of macrophages in mice with FAL was modulated by injections of either dexamethasone or the interleukins IL10 or IL3/IL14. The arteriogenic response was assessed by hind limb perfusion with laser Doppler measurements after 3, 7 and 14d. Suppressing inflammatory monocyte subtypes (M1) with dexamethasone led to impaired perfusion recovery after FAL in mice, whereas IL10 or IL4/IL13 application significantly increased perfusion recovery. This investigation demonstrates that a forced shift towards M2 macrophages improves the arteriogenic response. The distinct early increase and spatial distribution of M2 macrophages support the idea that this subtype plays a predominant role during collateral remodelling.

Temporal and spatial distribution of macrophage phenotype markers in the foreign body response to glutaraldehyde-crosslinked gelatin hydrogels

“…This latter study also reported increasing levels of an M2 marker, Chi313 , which is in agreement with our study in which we found increasing levels of the M2 markers Arg1 and CD163. Thus, although we and others found a lack of correlation between iNOS (M1) expression and fibrous capsule thickness, it is likely that macrophages with a predominantly M1 phenotype still contribute to the foreign body response, since persistent levels of M1 macrophages were observed over time, whereas they typically diminish over time in normal wound healing [7, 51]. In addition, both M1 and M2 macrophages secrete factors implicated in the formation of the fibrous capsule, including M1-secreted tumor necrosis factor-α (TNFα) [52] as well as M2-secreted platelet derived growth factor (PDGF) and transforming growth factor-β (TGF-β) [10, 20, 53].…”

Temporal remodeling of pial collaterals and functional deficits in a murine model of ischemic stroke

“…The contribution of peripheral-derived immune cells during collateral remodeling has recently been demonstrated (la Sala et al, 2012; Troidl et al, 2013). For example, pharmacological monocyte depletion and athymic nude mice that lack T cells display impaired arteriogenesis (Couffinhal et al, 1999; Heil et al, 2002).…”

GM-CSF Treated F4/80+ BMCs Improve Murine Hind Limb Ischemia Similar to M-CSF Differentiated Macrophages

“…Jetten et al also demonstrated that local delivery of 5×10 5 polarized M1 Mø cells (induced by lipopolysaccharide and interferon-gamma) or M2 (induced by IL-4 and IL-10) Mø subsets improved reperfusion recovery in a mouse hind limb ischemia model at day 14, although they did not examine the mechanism involved [29], [30]. Moreover, Troidl et al demonstrated that a forced shift toward M1 and M2 (by intravenous injections of IL-10 or IL-4/IL-13) macrophages improved the arteriogenic response [31]. Thus, the selective methods of culturing and treating M1Mø cells similar to M2Mø cells could be used clinically to help resolve the large number of cells required for BMCs therapy of CLI.…”