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oxLDL downregulates the dendritic cell homing factors CCR7 and CCL21.

Nickel T, Pfeiler S, Summo C, Kopp R, Meimarakis G, Sicic Z, Lambert M, Lackermair K, David R, Beiras-Fernandez A, Kaczmarek I, Weis M - Mediators Inflamm. (2012)

Bottom Line: CCL21- and CCR7-mRNA levels were significantly downregulated in atherosclerotic plaques versus non-atherosclerotic controls [90% for CCL21 and 81% for CCR7 (P < 0.01)].In vitro, oxLDL reduced CCR7 mRNA levels on DCs by 30% and protein levels by 46%.Furthermore, mRNA expression of CCL21 was significantly reduced by 50% (P < 0.05) and protein expression by 24% in HMECs by oxLDL (P < 0.05).

View Article: PubMed Central - PubMed

Affiliation: Medizinische Klinik und Poliklinik I, Campus Grosshadern, Ludwig-Maximilians University, 81377 Munich, Germany. tsnickel@web.de

ABSTRACT

Introduction: Dendritic cells (DCs) and oxLDL play an important role in the atherosclerotic process with DCs accumulating in the plaques during plaque progression. Our aim was to investigate the role of oxLDL in the modulation of the DC homing-receptor CCR7 and endothelial-ligand CCL21.

Methods and results: The expression of the DC homing-receptor CCR7 and its endothelial-ligand CCL21 was examined on atherosclerotic carotic plaques of 47 patients via qRT-PCR and immunofluorescence. In vitro, we studied the expression of CCR7 on DCs and CCL21 on human microvascular endothelial cells (HMECs) in response to oxLDL. CCL21- and CCR7-mRNA levels were significantly downregulated in atherosclerotic plaques versus non-atherosclerotic controls [90% for CCL21 and 81% for CCR7 (P < 0.01)]. In vitro, oxLDL reduced CCR7 mRNA levels on DCs by 30% and protein levels by 46%. Furthermore, mRNA expression of CCL21 was significantly reduced by 50% (P < 0.05) and protein expression by 24% in HMECs by oxLDL (P < 0.05).

Conclusions: The accumulation of DCs in atherosclerotic plaques appears to be related to a downregulation of chemokines and their ligands, which are known to regulate DC migration. oxLDL induces an in vitro downregulation of CCR7 and CCL21, which may play a role in the reduction of DC migration from the plaques.

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Protein expression of CCL21 and CCR7 on carotid plaque and aortic tissue. (a) Analysis of the CCL21 expressing structures in human aortic tissue. In the upper part the blue staining represents the cell nuclei (DAPI) and the red staining represents CCL21, positive structures (α-CCL21/6Ckine-Alexa488, pseudocolored). Scale bar 10 μm. To examine the vessel wall as CCL21 expressing structures (lower part) in human aorta tissue endothelial cells were stained with a PECAM-1 antibody (green, α-PECAM-1-Cy3, pseudocolored). The red staining represents CCL21 (α-CCL21/6Ckine-Atto594). The merged picture shows a co-localization of CCL21 and PECAM-1 in the vessel wall of the human aorta. Scale bar 50 μm. (b) The representative pictures show differences in the expression level of CCL21 (red, α-CCL21/6Ckine-Atto594) in aorta and carotid plaque tissue. A decreased CCL21-protein expression in carotid plaque compared to aorta tissue was shown by immunofluorescence microscopy. CCL21 is primarily expressed by the vasa vasorum of the vessel. Scale bar 50 μm. (c) A decreased CCR7 expression (green, α-CCR7-FITC) on CD4 positive cells (red, α-CD4-Atto594) was detectable in plaque tissue compared to aorta tissue. Arrows indicate the cells. Scale bar 20 μm. (d) Also a decreased CCR7 expression (green, α-CCR7-FITC) on CD83, positive cells (red, α-CD83-Atto5994) in aorta and plaque tissue is shown in the representative pictures. Arrows indicate the cells. Scale bar 20 μm.
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fig2: Protein expression of CCL21 and CCR7 on carotid plaque and aortic tissue. (a) Analysis of the CCL21 expressing structures in human aortic tissue. In the upper part the blue staining represents the cell nuclei (DAPI) and the red staining represents CCL21, positive structures (α-CCL21/6Ckine-Alexa488, pseudocolored). Scale bar 10 μm. To examine the vessel wall as CCL21 expressing structures (lower part) in human aorta tissue endothelial cells were stained with a PECAM-1 antibody (green, α-PECAM-1-Cy3, pseudocolored). The red staining represents CCL21 (α-CCL21/6Ckine-Atto594). The merged picture shows a co-localization of CCL21 and PECAM-1 in the vessel wall of the human aorta. Scale bar 50 μm. (b) The representative pictures show differences in the expression level of CCL21 (red, α-CCL21/6Ckine-Atto594) in aorta and carotid plaque tissue. A decreased CCL21-protein expression in carotid plaque compared to aorta tissue was shown by immunofluorescence microscopy. CCL21 is primarily expressed by the vasa vasorum of the vessel. Scale bar 50 μm. (c) A decreased CCR7 expression (green, α-CCR7-FITC) on CD4 positive cells (red, α-CD4-Atto594) was detectable in plaque tissue compared to aorta tissue. Arrows indicate the cells. Scale bar 20 μm. (d) Also a decreased CCR7 expression (green, α-CCR7-FITC) on CD83, positive cells (red, α-CD83-Atto5994) in aorta and plaque tissue is shown in the representative pictures. Arrows indicate the cells. Scale bar 20 μm.

Mentions: To analyze the location of CCL21 expressing cells, we stained the endothelial cells (α-PECAM-1-Cy3) in the aortic tissue section. This revealed a colocalization of the CCL21 and the vascular wall of the vasa vasorum (Figure 2(a)).


oxLDL downregulates the dendritic cell homing factors CCR7 and CCL21.

Nickel T, Pfeiler S, Summo C, Kopp R, Meimarakis G, Sicic Z, Lambert M, Lackermair K, David R, Beiras-Fernandez A, Kaczmarek I, Weis M - Mediators Inflamm. (2012)

Protein expression of CCL21 and CCR7 on carotid plaque and aortic tissue. (a) Analysis of the CCL21 expressing structures in human aortic tissue. In the upper part the blue staining represents the cell nuclei (DAPI) and the red staining represents CCL21, positive structures (α-CCL21/6Ckine-Alexa488, pseudocolored). Scale bar 10 μm. To examine the vessel wall as CCL21 expressing structures (lower part) in human aorta tissue endothelial cells were stained with a PECAM-1 antibody (green, α-PECAM-1-Cy3, pseudocolored). The red staining represents CCL21 (α-CCL21/6Ckine-Atto594). The merged picture shows a co-localization of CCL21 and PECAM-1 in the vessel wall of the human aorta. Scale bar 50 μm. (b) The representative pictures show differences in the expression level of CCL21 (red, α-CCL21/6Ckine-Atto594) in aorta and carotid plaque tissue. A decreased CCL21-protein expression in carotid plaque compared to aorta tissue was shown by immunofluorescence microscopy. CCL21 is primarily expressed by the vasa vasorum of the vessel. Scale bar 50 μm. (c) A decreased CCR7 expression (green, α-CCR7-FITC) on CD4 positive cells (red, α-CD4-Atto594) was detectable in plaque tissue compared to aorta tissue. Arrows indicate the cells. Scale bar 20 μm. (d) Also a decreased CCR7 expression (green, α-CCR7-FITC) on CD83, positive cells (red, α-CD83-Atto5994) in aorta and plaque tissue is shown in the representative pictures. Arrows indicate the cells. Scale bar 20 μm.
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fig2: Protein expression of CCL21 and CCR7 on carotid plaque and aortic tissue. (a) Analysis of the CCL21 expressing structures in human aortic tissue. In the upper part the blue staining represents the cell nuclei (DAPI) and the red staining represents CCL21, positive structures (α-CCL21/6Ckine-Alexa488, pseudocolored). Scale bar 10 μm. To examine the vessel wall as CCL21 expressing structures (lower part) in human aorta tissue endothelial cells were stained with a PECAM-1 antibody (green, α-PECAM-1-Cy3, pseudocolored). The red staining represents CCL21 (α-CCL21/6Ckine-Atto594). The merged picture shows a co-localization of CCL21 and PECAM-1 in the vessel wall of the human aorta. Scale bar 50 μm. (b) The representative pictures show differences in the expression level of CCL21 (red, α-CCL21/6Ckine-Atto594) in aorta and carotid plaque tissue. A decreased CCL21-protein expression in carotid plaque compared to aorta tissue was shown by immunofluorescence microscopy. CCL21 is primarily expressed by the vasa vasorum of the vessel. Scale bar 50 μm. (c) A decreased CCR7 expression (green, α-CCR7-FITC) on CD4 positive cells (red, α-CD4-Atto594) was detectable in plaque tissue compared to aorta tissue. Arrows indicate the cells. Scale bar 20 μm. (d) Also a decreased CCR7 expression (green, α-CCR7-FITC) on CD83, positive cells (red, α-CD83-Atto5994) in aorta and plaque tissue is shown in the representative pictures. Arrows indicate the cells. Scale bar 20 μm.
Mentions: To analyze the location of CCL21 expressing cells, we stained the endothelial cells (α-PECAM-1-Cy3) in the aortic tissue section. This revealed a colocalization of the CCL21 and the vascular wall of the vasa vasorum (Figure 2(a)).

Bottom Line: CCL21- and CCR7-mRNA levels were significantly downregulated in atherosclerotic plaques versus non-atherosclerotic controls [90% for CCL21 and 81% for CCR7 (P < 0.01)].In vitro, oxLDL reduced CCR7 mRNA levels on DCs by 30% and protein levels by 46%.Furthermore, mRNA expression of CCL21 was significantly reduced by 50% (P < 0.05) and protein expression by 24% in HMECs by oxLDL (P < 0.05).

View Article: PubMed Central - PubMed

Affiliation: Medizinische Klinik und Poliklinik I, Campus Grosshadern, Ludwig-Maximilians University, 81377 Munich, Germany. tsnickel@web.de

ABSTRACT

Introduction: Dendritic cells (DCs) and oxLDL play an important role in the atherosclerotic process with DCs accumulating in the plaques during plaque progression. Our aim was to investigate the role of oxLDL in the modulation of the DC homing-receptor CCR7 and endothelial-ligand CCL21.

Methods and results: The expression of the DC homing-receptor CCR7 and its endothelial-ligand CCL21 was examined on atherosclerotic carotic plaques of 47 patients via qRT-PCR and immunofluorescence. In vitro, we studied the expression of CCR7 on DCs and CCL21 on human microvascular endothelial cells (HMECs) in response to oxLDL. CCL21- and CCR7-mRNA levels were significantly downregulated in atherosclerotic plaques versus non-atherosclerotic controls [90% for CCL21 and 81% for CCR7 (P < 0.01)]. In vitro, oxLDL reduced CCR7 mRNA levels on DCs by 30% and protein levels by 46%. Furthermore, mRNA expression of CCL21 was significantly reduced by 50% (P < 0.05) and protein expression by 24% in HMECs by oxLDL (P < 0.05).

Conclusions: The accumulation of DCs in atherosclerotic plaques appears to be related to a downregulation of chemokines and their ligands, which are known to regulate DC migration. oxLDL induces an in vitro downregulation of CCR7 and CCL21, which may play a role in the reduction of DC migration from the plaques.

Show MeSH
Related in: MedlinePlus