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RGS1 regulates myeloid cell accumulation in atherosclerosis and aortic aneurysm rupture through altered chemokine signalling.

Patel J, McNeill E, Douglas G, Hale AB, de Bono J, Lee R, Iqbal AJ, Regan-Komito D, Stylianou E, Greaves DR, Channon KM - Nat Commun (2015)

Bottom Line: Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation.Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling.Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK [2] Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.

ABSTRACT
Chemokine signalling drives monocyte recruitment in atherosclerosis and aortic aneurysms. The mechanisms that lead to retention and accumulation of macrophages in the vascular wall remain unclear. Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation. Here we show that Rgs1 is upregulated in atherosclerotic plaque and aortic aneurysms. Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling. In early atherosclerotic lesions, Rgs1 regulates macrophage accumulation and is required for the formation and rupture of Angiotensin II-induced aortic aneurysms, through effects on leukocyte retention. Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.

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RGS1 promotes leukocyte accumulation in the aortic wall during Ang II-induced vascular inflammation.Flow cytometric analysis of bead-labelled aortic leukocytes in ApoE−/− and Rgs1−/−ApoE−/− mice that received Ang II infusion at 0.8 mg kg−1 per day for 5 days following fluorescent bead labelling of circulating inflammatory monocytes. (a) Representative dot plots shown for gated aortic cells of each positive population from ApoE−/− and Rgs1−/−ApoE−/− mice with representative percentages. Labels on both axes are on a log scale. (b) Quantification of the number of bead-labelled CD45+ cells in aortas of Ang II-infused mice at days 3 and 5. (c) Immunofluorescence microscopy of abdominal aortas from ApoE−/− mice at day 5 after Ang II infusion and bead labelling stained for Ly6C and 7/4 (red), 4′,6-diamidino-2-phenylindole (blue). Arrows indicate the presence of cells containing fluorescent beads (green) on the luminal side (L) of the aorta or within the internal elastic laminar (green autofluorescence). Adv, adventitia. **P<0.01 calculated using the Student’s t-test (n=5–7 per group. Data in b are expressed as mean±s.e.m.).
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f6: RGS1 promotes leukocyte accumulation in the aortic wall during Ang II-induced vascular inflammation.Flow cytometric analysis of bead-labelled aortic leukocytes in ApoE−/− and Rgs1−/−ApoE−/− mice that received Ang II infusion at 0.8 mg kg−1 per day for 5 days following fluorescent bead labelling of circulating inflammatory monocytes. (a) Representative dot plots shown for gated aortic cells of each positive population from ApoE−/− and Rgs1−/−ApoE−/− mice with representative percentages. Labels on both axes are on a log scale. (b) Quantification of the number of bead-labelled CD45+ cells in aortas of Ang II-infused mice at days 3 and 5. (c) Immunofluorescence microscopy of abdominal aortas from ApoE−/− mice at day 5 after Ang II infusion and bead labelling stained for Ly6C and 7/4 (red), 4′,6-diamidino-2-phenylindole (blue). Arrows indicate the presence of cells containing fluorescent beads (green) on the luminal side (L) of the aorta or within the internal elastic laminar (green autofluorescence). Adv, adventitia. **P<0.01 calculated using the Student’s t-test (n=5–7 per group. Data in b are expressed as mean±s.e.m.).

Mentions: To specifically address the role of Rgs1 in the accumulation or emigration of monocyte-derived cells in the aortic wall during aneurysm development, we used a pulse-chase approach to track bead-labelled monocytes in aortas following Ang II infusion. Inflammatory 7/4hi monocytes were labelled in vivo with fluorescent latex microbeads and administered intravenously (i.v.) at the time of osmotic mini pump implantation2324. Aortic cell numbers were quantified by flow cytometry at days 3 and 5 after bead injection (Fig. 6a). At 3 days post Ang II infusion, the time of peak monocyte recruitment from the bloodstream, bead-positive leukocyte content in aortas was similar between ApoE−/− and Rgs1−/−ApoE−/− mice, implying that monocyte recruitment was similar between the groups (Fig. 6b). However, by day 5 after the initiation of Ang II infusion, bead-positive CD45+ cells were significantly higher in ApoE−/− aortas compared with Rgs1−/−ApoE−/− mice, suggesting that RGS1 promotes the accumulation of ApoE−/− monocytes in aortic tissue, rather than emigration. Importantly, these findings likely underestimate the magnitude of accumulation of bead-labelled monocytes, since we found several ApoE−/− mice with aneurysms at the time of harvest, which were excluded from the analysis because of the confounding effect of blood cells trapped in aneurysms, to the flow cytometric analysis of aortic cells. Bead-labelled monocytes localized to areas of the subintimal space of the vessel wall and were 7/4 and Ly6C positive (Fig. 6c). In contrast to the difference in bead-labelled cells in the aortic wall, there was no difference in the number of circulating bead-labelled inflammatory monocytes between ApoE−/− and Rgs1−/−ApoE−/− mice at day 3 or 5 (Supplementary Fig. 9). Together these data suggest that RGS1 is a mediator of inflammatory monocyte accumulation in aortic aneurysms.


RGS1 regulates myeloid cell accumulation in atherosclerosis and aortic aneurysm rupture through altered chemokine signalling.

Patel J, McNeill E, Douglas G, Hale AB, de Bono J, Lee R, Iqbal AJ, Regan-Komito D, Stylianou E, Greaves DR, Channon KM - Nat Commun (2015)

RGS1 promotes leukocyte accumulation in the aortic wall during Ang II-induced vascular inflammation.Flow cytometric analysis of bead-labelled aortic leukocytes in ApoE−/− and Rgs1−/−ApoE−/− mice that received Ang II infusion at 0.8 mg kg−1 per day for 5 days following fluorescent bead labelling of circulating inflammatory monocytes. (a) Representative dot plots shown for gated aortic cells of each positive population from ApoE−/− and Rgs1−/−ApoE−/− mice with representative percentages. Labels on both axes are on a log scale. (b) Quantification of the number of bead-labelled CD45+ cells in aortas of Ang II-infused mice at days 3 and 5. (c) Immunofluorescence microscopy of abdominal aortas from ApoE−/− mice at day 5 after Ang II infusion and bead labelling stained for Ly6C and 7/4 (red), 4′,6-diamidino-2-phenylindole (blue). Arrows indicate the presence of cells containing fluorescent beads (green) on the luminal side (L) of the aorta or within the internal elastic laminar (green autofluorescence). Adv, adventitia. **P<0.01 calculated using the Student’s t-test (n=5–7 per group. Data in b are expressed as mean±s.e.m.).
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f6: RGS1 promotes leukocyte accumulation in the aortic wall during Ang II-induced vascular inflammation.Flow cytometric analysis of bead-labelled aortic leukocytes in ApoE−/− and Rgs1−/−ApoE−/− mice that received Ang II infusion at 0.8 mg kg−1 per day for 5 days following fluorescent bead labelling of circulating inflammatory monocytes. (a) Representative dot plots shown for gated aortic cells of each positive population from ApoE−/− and Rgs1−/−ApoE−/− mice with representative percentages. Labels on both axes are on a log scale. (b) Quantification of the number of bead-labelled CD45+ cells in aortas of Ang II-infused mice at days 3 and 5. (c) Immunofluorescence microscopy of abdominal aortas from ApoE−/− mice at day 5 after Ang II infusion and bead labelling stained for Ly6C and 7/4 (red), 4′,6-diamidino-2-phenylindole (blue). Arrows indicate the presence of cells containing fluorescent beads (green) on the luminal side (L) of the aorta or within the internal elastic laminar (green autofluorescence). Adv, adventitia. **P<0.01 calculated using the Student’s t-test (n=5–7 per group. Data in b are expressed as mean±s.e.m.).
Mentions: To specifically address the role of Rgs1 in the accumulation or emigration of monocyte-derived cells in the aortic wall during aneurysm development, we used a pulse-chase approach to track bead-labelled monocytes in aortas following Ang II infusion. Inflammatory 7/4hi monocytes were labelled in vivo with fluorescent latex microbeads and administered intravenously (i.v.) at the time of osmotic mini pump implantation2324. Aortic cell numbers were quantified by flow cytometry at days 3 and 5 after bead injection (Fig. 6a). At 3 days post Ang II infusion, the time of peak monocyte recruitment from the bloodstream, bead-positive leukocyte content in aortas was similar between ApoE−/− and Rgs1−/−ApoE−/− mice, implying that monocyte recruitment was similar between the groups (Fig. 6b). However, by day 5 after the initiation of Ang II infusion, bead-positive CD45+ cells were significantly higher in ApoE−/− aortas compared with Rgs1−/−ApoE−/− mice, suggesting that RGS1 promotes the accumulation of ApoE−/− monocytes in aortic tissue, rather than emigration. Importantly, these findings likely underestimate the magnitude of accumulation of bead-labelled monocytes, since we found several ApoE−/− mice with aneurysms at the time of harvest, which were excluded from the analysis because of the confounding effect of blood cells trapped in aneurysms, to the flow cytometric analysis of aortic cells. Bead-labelled monocytes localized to areas of the subintimal space of the vessel wall and were 7/4 and Ly6C positive (Fig. 6c). In contrast to the difference in bead-labelled cells in the aortic wall, there was no difference in the number of circulating bead-labelled inflammatory monocytes between ApoE−/− and Rgs1−/−ApoE−/− mice at day 3 or 5 (Supplementary Fig. 9). Together these data suggest that RGS1 is a mediator of inflammatory monocyte accumulation in aortic aneurysms.

Bottom Line: Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation.Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling.Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK [2] Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.

ABSTRACT
Chemokine signalling drives monocyte recruitment in atherosclerosis and aortic aneurysms. The mechanisms that lead to retention and accumulation of macrophages in the vascular wall remain unclear. Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation. Here we show that Rgs1 is upregulated in atherosclerotic plaque and aortic aneurysms. Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling. In early atherosclerotic lesions, Rgs1 regulates macrophage accumulation and is required for the formation and rupture of Angiotensin II-induced aortic aneurysms, through effects on leukocyte retention. Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.

Show MeSH
Related in: MedlinePlus