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Triglyceride-Rich Lipoproteins Modulate the Distribution and Extravasation of Ly6C/Gr1(low) Monocytes.

Saja MF, Baudino L, Jackson WD, Cook HT, Malik TH, Fossati-Jimack L, Ruseva M, Pickering MC, Woollard KJ, Botto M - Cell Rep (2015)

Bottom Line: Here, we report that in the presence of elevated levels of triglyceride-rich lipoproteins, induced by administration of poloxamer 407, the blood numbers of non-classical Ly6C/Gr1(low) monocytes drop, while the number of bone marrow progenitors remains similar.We observed an increased crawling and retention of the Gr1(low) monocytes at the endothelial interface and a marked accumulation of CD68(+) macrophages in several organs.The behavior of these cells in response to dyslipidemia highlights the significant impact that high levels of triglyceride-rich lipoproteins may have on innate immune cells.

View Article: PubMed Central - PubMed

Affiliation: Centre for Complement and Inflammation Research, Division of Immunology and Inflammation, Department of Medicine, Imperial College London, Du Cane Road, London W12 ONN, UK.

No MeSH data available.


Related in: MedlinePlus

Tracing Monocyte Subset Migration by Adoptive Transfer(A) Gr1lowGFPhigh or Gr1highGFPlow blood monocytes were sorted from CD45.2 Cx3cr1gfp/gfp mice. 0.1 × 106 Gr1lowGFPhigh or Gr1highGFPlow sorted monocytes were injected intravenously into CD45.1.B6 mice. At 16 hr, mice were injected with CD11b antibody to exclude blood contamination. Mice were perfused with PBS, and organs (liver, heart, kidney, and spleen) were analyzed for monocyte migration. Dot plot overlays display total cells (gray) and CD45.2+CD11b−GFP+ cells (red).(B) Quantitative representation of (A). Data are from two independent experiments (n = 4); values represent the mean ± SE of number of cells per gram of organ.(C) B6 mice were treated with P-407 for 21 days or for 14 days followed by 7-day treatment with PBS. Mice treated with PBS for 21 days were used as controls. Data are expressed as percentage of Gr1low and Gr1high blood monocytes. Values represent mean ± SE, n = 4 mice per group. Significant p values are indicated (∗∗∗p < 0.001; ns, nonsignificant; unpaired t test).See also Figure S5.
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fig5: Tracing Monocyte Subset Migration by Adoptive Transfer(A) Gr1lowGFPhigh or Gr1highGFPlow blood monocytes were sorted from CD45.2 Cx3cr1gfp/gfp mice. 0.1 × 106 Gr1lowGFPhigh or Gr1highGFPlow sorted monocytes were injected intravenously into CD45.1.B6 mice. At 16 hr, mice were injected with CD11b antibody to exclude blood contamination. Mice were perfused with PBS, and organs (liver, heart, kidney, and spleen) were analyzed for monocyte migration. Dot plot overlays display total cells (gray) and CD45.2+CD11b−GFP+ cells (red).(B) Quantitative representation of (A). Data are from two independent experiments (n = 4); values represent the mean ± SE of number of cells per gram of organ.(C) B6 mice were treated with P-407 for 21 days or for 14 days followed by 7-day treatment with PBS. Mice treated with PBS for 21 days were used as controls. Data are expressed as percentage of Gr1low and Gr1high blood monocytes. Values represent mean ± SE, n = 4 mice per group. Significant p values are indicated (∗∗∗p < 0.001; ns, nonsignificant; unpaired t test).See also Figure S5.

Mentions: To formally demonstrate that Gr1low monocytes were indeed trafficking into the organs in the P-407-treated mice, we performed BM transplant and adoptive transfer experiments using the Cx3cr1gfp/gfp mice. Two months after the engraftment of the Cx3cr1gfp/gfp BM cells into B6 recipients, we detected a large number of GFP+ cells in all the organs prior to any P-407 intervention (Figure S4D), probably as a result of the damage caused by irradiation and repopulation of tissue resident macrophages from BM progenitors (Hashimoto et al., 2013), and thus, we abandoned this approach. We next adoptively transferred Gr1lowGFPhigh or Gr1highGFPlow monocytes, isolated from CD45.2Cx3cr1gfp/gfp mice, into CD45.1B6 animals pretreated with either P-407 or PBS for 2 weeks. Recipients were sacrificed 16 hr after the adoptive transfer. To exclude the contamination from circulating monocytes, we also injected an anti-CD11b antibody that labeled blood monocytes immediately prior to the perfusion of the organs. Adoptively transferred Gr1lowGFPhigh monocytes were detected in the liver, spleen, and kidney of P-407-treated animals to a much greater extent than in the PBS-treated recipients (Figures 5A and 5B). There was no obvious recruitment in the heart, possible because of different kinetics of macrophage accumulation (Figure 5B). Of note, we found no increase of Gr1highGFPlow monocytes in the P-407-treated organs (Figures 5A and 5B), corroborating our earlier assumption that it was mainly the Gr1low subpopulation that had extravasated in the tissues in response to the hyper-TGRL environment. Furthermore, Gr1lowGFPhigh monocytes isolated from P-407-treated CD45.2Cx3cr1gfp/gfp mice did not extravasate when adoptively transferred into PBS-treated recipients (Figure S5A). The monocyte expression of CD11b, CCR2, CD68, LFA-1, and CCR5 (Figures S5B–S5F) did not change in response to the P-407 treatment, demonstrating that neither the P-407-induced hyper-TGRL environment nor the compound itself had altered the phenotype of the monocytes. To determine if the TGRL-induced drop in the number of Gr1low monocytes was a reversible process, we treated mice with P-407 for 2 weeks and then stopped the treatment. On stopping the P-407 administration, lipid levels returned to normal by 72 hr (see Figure S1) and the Gr1low fraction returned to pre-treatment levels by 2 weeks (Figure 5C).


Triglyceride-Rich Lipoproteins Modulate the Distribution and Extravasation of Ly6C/Gr1(low) Monocytes.

Saja MF, Baudino L, Jackson WD, Cook HT, Malik TH, Fossati-Jimack L, Ruseva M, Pickering MC, Woollard KJ, Botto M - Cell Rep (2015)

Tracing Monocyte Subset Migration by Adoptive Transfer(A) Gr1lowGFPhigh or Gr1highGFPlow blood monocytes were sorted from CD45.2 Cx3cr1gfp/gfp mice. 0.1 × 106 Gr1lowGFPhigh or Gr1highGFPlow sorted monocytes were injected intravenously into CD45.1.B6 mice. At 16 hr, mice were injected with CD11b antibody to exclude blood contamination. Mice were perfused with PBS, and organs (liver, heart, kidney, and spleen) were analyzed for monocyte migration. Dot plot overlays display total cells (gray) and CD45.2+CD11b−GFP+ cells (red).(B) Quantitative representation of (A). Data are from two independent experiments (n = 4); values represent the mean ± SE of number of cells per gram of organ.(C) B6 mice were treated with P-407 for 21 days or for 14 days followed by 7-day treatment with PBS. Mice treated with PBS for 21 days were used as controls. Data are expressed as percentage of Gr1low and Gr1high blood monocytes. Values represent mean ± SE, n = 4 mice per group. Significant p values are indicated (∗∗∗p < 0.001; ns, nonsignificant; unpaired t test).See also Figure S5.
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Related In: Results  -  Collection

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fig5: Tracing Monocyte Subset Migration by Adoptive Transfer(A) Gr1lowGFPhigh or Gr1highGFPlow blood monocytes were sorted from CD45.2 Cx3cr1gfp/gfp mice. 0.1 × 106 Gr1lowGFPhigh or Gr1highGFPlow sorted monocytes were injected intravenously into CD45.1.B6 mice. At 16 hr, mice were injected with CD11b antibody to exclude blood contamination. Mice were perfused with PBS, and organs (liver, heart, kidney, and spleen) were analyzed for monocyte migration. Dot plot overlays display total cells (gray) and CD45.2+CD11b−GFP+ cells (red).(B) Quantitative representation of (A). Data are from two independent experiments (n = 4); values represent the mean ± SE of number of cells per gram of organ.(C) B6 mice were treated with P-407 for 21 days or for 14 days followed by 7-day treatment with PBS. Mice treated with PBS for 21 days were used as controls. Data are expressed as percentage of Gr1low and Gr1high blood monocytes. Values represent mean ± SE, n = 4 mice per group. Significant p values are indicated (∗∗∗p < 0.001; ns, nonsignificant; unpaired t test).See also Figure S5.
Mentions: To formally demonstrate that Gr1low monocytes were indeed trafficking into the organs in the P-407-treated mice, we performed BM transplant and adoptive transfer experiments using the Cx3cr1gfp/gfp mice. Two months after the engraftment of the Cx3cr1gfp/gfp BM cells into B6 recipients, we detected a large number of GFP+ cells in all the organs prior to any P-407 intervention (Figure S4D), probably as a result of the damage caused by irradiation and repopulation of tissue resident macrophages from BM progenitors (Hashimoto et al., 2013), and thus, we abandoned this approach. We next adoptively transferred Gr1lowGFPhigh or Gr1highGFPlow monocytes, isolated from CD45.2Cx3cr1gfp/gfp mice, into CD45.1B6 animals pretreated with either P-407 or PBS for 2 weeks. Recipients were sacrificed 16 hr after the adoptive transfer. To exclude the contamination from circulating monocytes, we also injected an anti-CD11b antibody that labeled blood monocytes immediately prior to the perfusion of the organs. Adoptively transferred Gr1lowGFPhigh monocytes were detected in the liver, spleen, and kidney of P-407-treated animals to a much greater extent than in the PBS-treated recipients (Figures 5A and 5B). There was no obvious recruitment in the heart, possible because of different kinetics of macrophage accumulation (Figure 5B). Of note, we found no increase of Gr1highGFPlow monocytes in the P-407-treated organs (Figures 5A and 5B), corroborating our earlier assumption that it was mainly the Gr1low subpopulation that had extravasated in the tissues in response to the hyper-TGRL environment. Furthermore, Gr1lowGFPhigh monocytes isolated from P-407-treated CD45.2Cx3cr1gfp/gfp mice did not extravasate when adoptively transferred into PBS-treated recipients (Figure S5A). The monocyte expression of CD11b, CCR2, CD68, LFA-1, and CCR5 (Figures S5B–S5F) did not change in response to the P-407 treatment, demonstrating that neither the P-407-induced hyper-TGRL environment nor the compound itself had altered the phenotype of the monocytes. To determine if the TGRL-induced drop in the number of Gr1low monocytes was a reversible process, we treated mice with P-407 for 2 weeks and then stopped the treatment. On stopping the P-407 administration, lipid levels returned to normal by 72 hr (see Figure S1) and the Gr1low fraction returned to pre-treatment levels by 2 weeks (Figure 5C).

Bottom Line: Here, we report that in the presence of elevated levels of triglyceride-rich lipoproteins, induced by administration of poloxamer 407, the blood numbers of non-classical Ly6C/Gr1(low) monocytes drop, while the number of bone marrow progenitors remains similar.We observed an increased crawling and retention of the Gr1(low) monocytes at the endothelial interface and a marked accumulation of CD68(+) macrophages in several organs.The behavior of these cells in response to dyslipidemia highlights the significant impact that high levels of triglyceride-rich lipoproteins may have on innate immune cells.

View Article: PubMed Central - PubMed

Affiliation: Centre for Complement and Inflammation Research, Division of Immunology and Inflammation, Department of Medicine, Imperial College London, Du Cane Road, London W12 ONN, UK.

No MeSH data available.


Related in: MedlinePlus