Limits...
Human antimicrobial peptide LL-37 is present in atherosclerotic plaques and induces death of vascular smooth muscle cells: a laboratory study.

Ciornei CD, Tapper H, Bjartell A, Sternby NH, Bodelsson M - BMC Cardiovasc Disord (2006)

Bottom Line: The direct effects of LL-37 on cultured vascular smooth muscle cells and isolated neutrophil granulocytes were investigated with morphological, biochemical and flow cytometry analysis.Neutrophil granulocytes were resistant to these effects of LL-37.The findings suggest a role for LL-37 as a mediator of immune cell-induced death of vascular smooth muscle cells in atherosclerosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Sciences, Division of Anaesthesiology and Intensive Care, Lund University, Lund, Sweden. cristina.ciornei@med.lu.se <cristina.ciornei@med.lu.se>

ABSTRACT

Background: Death of smooth muscle cells in the atherosclerotic plaques makes the plaques more prone to rupture, which can initiate an acute ischemic event. The development of atherosclerosis includes the migration of immune cells e.g. monocytes/macrophages and T lymphocytes into the lesions. Immune cells can release antimicrobial peptides. One of these, human cathelicidin antimicrobial peptide hCAP-18, is cleaved by proteinase 3 generating a 4.5 kDa C-terminal fragment named LL-37, which has been shown to be cytotoxic. The aim of the study was to explore a potential role of LL-37 in the pathophysiology of atherosclerosis.

Methods: We investigated the presence of LL-37 in human atherosclerotic lesions obtained at autopsy using immunohistochemistry. The direct effects of LL-37 on cultured vascular smooth muscle cells and isolated neutrophil granulocytes were investigated with morphological, biochemical and flow cytometry analysis.

Results: The neointima of atherosclerotic plaques was found to contain LL-37-like immunoreactivity, mainly in macrophages. In cultured smooth muscle cells, LL-37 at 30 mug/ml caused cell shrinkage, membrane blebbing, nuclear condensation, DNA fragmentation and an increase in caspase-3 activity as studied by microscopy, ELISA and enzyme activity assay, respectively. Flow cytometry demonstrated that LL-37 in a subset of the cells caused a small but rapidly developing increase in membrane permeability to propidium iodide, followed by a gradual development of FITC-annexin V binding. Another cell population stained heavily with both propidium iodide and FITC-annexin V. Neutrophil granulocytes were resistant to these effects of LL-37.

Conclusion: This study shows that LL-37 is present in atherosclerotic lesions and that it induces death of vascular smooth muscle cells. In a subset of cells, the changes indicate the development of apoptosis triggered by an initial mild perturbation of plasma membrane integrity. The findings suggest a role for LL-37 as a mediator of immune cell-induced death of vascular smooth muscle cells in atherosclerosis.

Show MeSH

Related in: MedlinePlus

Release of LDH from cultured vascular smooth muscle cells. Cells were incubated for 1, 3 or 7 hours without (Control, ○) or with LL-37 at 10 (●) or 30 (■) μg/ml. The release of LDH was significantly increased from cells incubated for 1, 3 and 7 hours with LL-37 at 30 μg/ml (n = 7, *P < 0.05, One way repeated measures ANOVA followed by Holm-Sidak test). Values are means ± S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1764755&req=5

Figure 5: Release of LDH from cultured vascular smooth muscle cells. Cells were incubated for 1, 3 or 7 hours without (Control, ○) or with LL-37 at 10 (●) or 30 (■) μg/ml. The release of LDH was significantly increased from cells incubated for 1, 3 and 7 hours with LL-37 at 30 μg/ml (n = 7, *P < 0.05, One way repeated measures ANOVA followed by Holm-Sidak test). Values are means ± S.E.M.

Mentions: Fig. 5 shows that the release of LDH activity from the vascular smooth muscle cells into the cell culture medium was significantly higher from cells incubated with LL-37 (30 μg/ml), as compared to controls (P < 0.05). The LDH increase, observed already after incubation with LL-37 for one h, suggests a loss of cell membrane integrity.


Human antimicrobial peptide LL-37 is present in atherosclerotic plaques and induces death of vascular smooth muscle cells: a laboratory study.

Ciornei CD, Tapper H, Bjartell A, Sternby NH, Bodelsson M - BMC Cardiovasc Disord (2006)

Release of LDH from cultured vascular smooth muscle cells. Cells were incubated for 1, 3 or 7 hours without (Control, ○) or with LL-37 at 10 (●) or 30 (■) μg/ml. The release of LDH was significantly increased from cells incubated for 1, 3 and 7 hours with LL-37 at 30 μg/ml (n = 7, *P < 0.05, One way repeated measures ANOVA followed by Holm-Sidak test). Values are means ± S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1764755&req=5

Figure 5: Release of LDH from cultured vascular smooth muscle cells. Cells were incubated for 1, 3 or 7 hours without (Control, ○) or with LL-37 at 10 (●) or 30 (■) μg/ml. The release of LDH was significantly increased from cells incubated for 1, 3 and 7 hours with LL-37 at 30 μg/ml (n = 7, *P < 0.05, One way repeated measures ANOVA followed by Holm-Sidak test). Values are means ± S.E.M.
Mentions: Fig. 5 shows that the release of LDH activity from the vascular smooth muscle cells into the cell culture medium was significantly higher from cells incubated with LL-37 (30 μg/ml), as compared to controls (P < 0.05). The LDH increase, observed already after incubation with LL-37 for one h, suggests a loss of cell membrane integrity.

Bottom Line: The direct effects of LL-37 on cultured vascular smooth muscle cells and isolated neutrophil granulocytes were investigated with morphological, biochemical and flow cytometry analysis.Neutrophil granulocytes were resistant to these effects of LL-37.The findings suggest a role for LL-37 as a mediator of immune cell-induced death of vascular smooth muscle cells in atherosclerosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Sciences, Division of Anaesthesiology and Intensive Care, Lund University, Lund, Sweden. cristina.ciornei@med.lu.se <cristina.ciornei@med.lu.se>

ABSTRACT

Background: Death of smooth muscle cells in the atherosclerotic plaques makes the plaques more prone to rupture, which can initiate an acute ischemic event. The development of atherosclerosis includes the migration of immune cells e.g. monocytes/macrophages and T lymphocytes into the lesions. Immune cells can release antimicrobial peptides. One of these, human cathelicidin antimicrobial peptide hCAP-18, is cleaved by proteinase 3 generating a 4.5 kDa C-terminal fragment named LL-37, which has been shown to be cytotoxic. The aim of the study was to explore a potential role of LL-37 in the pathophysiology of atherosclerosis.

Methods: We investigated the presence of LL-37 in human atherosclerotic lesions obtained at autopsy using immunohistochemistry. The direct effects of LL-37 on cultured vascular smooth muscle cells and isolated neutrophil granulocytes were investigated with morphological, biochemical and flow cytometry analysis.

Results: The neointima of atherosclerotic plaques was found to contain LL-37-like immunoreactivity, mainly in macrophages. In cultured smooth muscle cells, LL-37 at 30 mug/ml caused cell shrinkage, membrane blebbing, nuclear condensation, DNA fragmentation and an increase in caspase-3 activity as studied by microscopy, ELISA and enzyme activity assay, respectively. Flow cytometry demonstrated that LL-37 in a subset of the cells caused a small but rapidly developing increase in membrane permeability to propidium iodide, followed by a gradual development of FITC-annexin V binding. Another cell population stained heavily with both propidium iodide and FITC-annexin V. Neutrophil granulocytes were resistant to these effects of LL-37.

Conclusion: This study shows that LL-37 is present in atherosclerotic lesions and that it induces death of vascular smooth muscle cells. In a subset of cells, the changes indicate the development of apoptosis triggered by an initial mild perturbation of plasma membrane integrity. The findings suggest a role for LL-37 as a mediator of immune cell-induced death of vascular smooth muscle cells in atherosclerosis.

Show MeSH
Related in: MedlinePlus