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Osteopontin expression in the brain triggers localized inflammation and cell death when immune cells are activated by pertussis toxin.

Marcondes MC, Ojakian R, Bortell N, Flynn C, Conti B, Fox HS - Mediators Inflamm. (2014)

Bottom Line: Interestingly, inflammatory infiltrate was only found when the OPN-vector was combined with a peripheral treatment with pertussis toxin (Ptx), which activated peripheral cells to express the OPN receptor CD44v6.In Ptx-treated OPN KOs, apoptotic TUNEL+ cells surrounding the OPN expression site increased, compared to β-gal.Together, these results show that local OPN expression combined with a peripheral inflammatory stimulus, such as Ptx, may be implicated in the development of brain inflammation and induction of cell death, by driving a molecular pattern characteristic of cytotoxicity.

View Article: PubMed Central - PubMed

Affiliation: Molecular and Cellular Neuroscience Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

ABSTRACT
Upregulation of osteopontin (OPN) is a characteristic of central nervous system pathologies. However, the role of OPN in inflammation is still controversial, since it can both prevent cell death and induce the migration of potentially damaging inflammatory cells. To understand the role of OPN in inflammation and cell survival, we expressed OPN, utilizing an adenoviral vector, in the caudoputamen of mice deficient in OPN, using beta-galactosidase- (β-gal-) expressing vector as control. The tissue pathology and the expression of proinflammatory genes were compared in both treatments. Interestingly, inflammatory infiltrate was only found when the OPN-vector was combined with a peripheral treatment with pertussis toxin (Ptx), which activated peripheral cells to express the OPN receptor CD44v6. Relative to β-gal, OPN increased the levels of inflammatory markers, including IL13Rα1, CXCR3, and CD40L. In Ptx-treated OPN KOs, apoptotic TUNEL+ cells surrounding the OPN expression site increased, compared to β-gal. Together, these results show that local OPN expression combined with a peripheral inflammatory stimulus, such as Ptx, may be implicated in the development of brain inflammation and induction of cell death, by driving a molecular pattern characteristic of cytotoxicity. These are characteristics of inflammatory pathologies of the CNS in which OPN upregulation is a hallmark.

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Number of TUNEL-positive cells in brain sections after the injection adenoviral vector constructs. The number of TUNEL-labelled apoptotic cells was counted under microscope in 5 sections from each of 6 animals/group, 21 days after the injection of β-gal or OPN constructs. The total number of TUNEL+ cells/lobe was estimated by applying the Abercrombie correction factor. (a) Total number of TUNEL+ cells in the brain lobe injected with the adenoviral vector bearing β-gal or OPN gene, in OPN−/− animals that were previously treated or not with i.p. Ptx. (b) Percentage of TUNEL+ cells identified within the focal lesion. *P < 0.05, ANOVA followed by Bonferroni's post hoc test, to include contralateral lobe putamen sections. (c) Representative section of the brain of OPN + Ptx animal, at the injection site, showing the lesion perimeter (dotted line) and TUNEL+ cells (black arrows) both within and outside the lesion limits.
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fig3: Number of TUNEL-positive cells in brain sections after the injection adenoviral vector constructs. The number of TUNEL-labelled apoptotic cells was counted under microscope in 5 sections from each of 6 animals/group, 21 days after the injection of β-gal or OPN constructs. The total number of TUNEL+ cells/lobe was estimated by applying the Abercrombie correction factor. (a) Total number of TUNEL+ cells in the brain lobe injected with the adenoviral vector bearing β-gal or OPN gene, in OPN−/− animals that were previously treated or not with i.p. Ptx. (b) Percentage of TUNEL+ cells identified within the focal lesion. *P < 0.05, ANOVA followed by Bonferroni's post hoc test, to include contralateral lobe putamen sections. (c) Representative section of the brain of OPN + Ptx animal, at the injection site, showing the lesion perimeter (dotted line) and TUNEL+ cells (black arrows) both within and outside the lesion limits.

Mentions: Since both the molecular profile induced by OPN and the inflammation induced locally by the peripheral treatment with Ptx can be associated with neuronal damage and cell death, we next examined whether there were differences in the number of apoptotic cell bodies in the brain surrounding the vector injection site, as well as outside of the defined lesion perimeter (Figure 3(c)). In animals that received β-gal, either with or without Ptx treatment, apoptosis was not detectable near the infection site (Figures 3(a) and 3(b)). In contrast, OPN-injected animals had an increase in TUNEL+ cells by the lesion, especially upon peripheral stimulation with Ptx (Figures 3(a) and 3(b)). The identification of the dying cells was compromised by the strong background of picnotic bodies (not shown), interestingly, though, about 50% of the TUNEL+ cells were concentrated within the lesion perimeter (Figure 3(b)), suggesting that they could be either neurons or inflammatory cells. Figure 3(c) shows a representative section of a Ptx-stimulated, OPN-encoding virus injected brain, demonstrating the lesion perimeter and the presence of TUNEL+ cells.


Osteopontin expression in the brain triggers localized inflammation and cell death when immune cells are activated by pertussis toxin.

Marcondes MC, Ojakian R, Bortell N, Flynn C, Conti B, Fox HS - Mediators Inflamm. (2014)

Number of TUNEL-positive cells in brain sections after the injection adenoviral vector constructs. The number of TUNEL-labelled apoptotic cells was counted under microscope in 5 sections from each of 6 animals/group, 21 days after the injection of β-gal or OPN constructs. The total number of TUNEL+ cells/lobe was estimated by applying the Abercrombie correction factor. (a) Total number of TUNEL+ cells in the brain lobe injected with the adenoviral vector bearing β-gal or OPN gene, in OPN−/− animals that were previously treated or not with i.p. Ptx. (b) Percentage of TUNEL+ cells identified within the focal lesion. *P < 0.05, ANOVA followed by Bonferroni's post hoc test, to include contralateral lobe putamen sections. (c) Representative section of the brain of OPN + Ptx animal, at the injection site, showing the lesion perimeter (dotted line) and TUNEL+ cells (black arrows) both within and outside the lesion limits.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4265371&req=5

fig3: Number of TUNEL-positive cells in brain sections after the injection adenoviral vector constructs. The number of TUNEL-labelled apoptotic cells was counted under microscope in 5 sections from each of 6 animals/group, 21 days after the injection of β-gal or OPN constructs. The total number of TUNEL+ cells/lobe was estimated by applying the Abercrombie correction factor. (a) Total number of TUNEL+ cells in the brain lobe injected with the adenoviral vector bearing β-gal or OPN gene, in OPN−/− animals that were previously treated or not with i.p. Ptx. (b) Percentage of TUNEL+ cells identified within the focal lesion. *P < 0.05, ANOVA followed by Bonferroni's post hoc test, to include contralateral lobe putamen sections. (c) Representative section of the brain of OPN + Ptx animal, at the injection site, showing the lesion perimeter (dotted line) and TUNEL+ cells (black arrows) both within and outside the lesion limits.
Mentions: Since both the molecular profile induced by OPN and the inflammation induced locally by the peripheral treatment with Ptx can be associated with neuronal damage and cell death, we next examined whether there were differences in the number of apoptotic cell bodies in the brain surrounding the vector injection site, as well as outside of the defined lesion perimeter (Figure 3(c)). In animals that received β-gal, either with or without Ptx treatment, apoptosis was not detectable near the infection site (Figures 3(a) and 3(b)). In contrast, OPN-injected animals had an increase in TUNEL+ cells by the lesion, especially upon peripheral stimulation with Ptx (Figures 3(a) and 3(b)). The identification of the dying cells was compromised by the strong background of picnotic bodies (not shown), interestingly, though, about 50% of the TUNEL+ cells were concentrated within the lesion perimeter (Figure 3(b)), suggesting that they could be either neurons or inflammatory cells. Figure 3(c) shows a representative section of a Ptx-stimulated, OPN-encoding virus injected brain, demonstrating the lesion perimeter and the presence of TUNEL+ cells.

Bottom Line: Interestingly, inflammatory infiltrate was only found when the OPN-vector was combined with a peripheral treatment with pertussis toxin (Ptx), which activated peripheral cells to express the OPN receptor CD44v6.In Ptx-treated OPN KOs, apoptotic TUNEL+ cells surrounding the OPN expression site increased, compared to β-gal.Together, these results show that local OPN expression combined with a peripheral inflammatory stimulus, such as Ptx, may be implicated in the development of brain inflammation and induction of cell death, by driving a molecular pattern characteristic of cytotoxicity.

View Article: PubMed Central - PubMed

Affiliation: Molecular and Cellular Neuroscience Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

ABSTRACT
Upregulation of osteopontin (OPN) is a characteristic of central nervous system pathologies. However, the role of OPN in inflammation is still controversial, since it can both prevent cell death and induce the migration of potentially damaging inflammatory cells. To understand the role of OPN in inflammation and cell survival, we expressed OPN, utilizing an adenoviral vector, in the caudoputamen of mice deficient in OPN, using beta-galactosidase- (β-gal-) expressing vector as control. The tissue pathology and the expression of proinflammatory genes were compared in both treatments. Interestingly, inflammatory infiltrate was only found when the OPN-vector was combined with a peripheral treatment with pertussis toxin (Ptx), which activated peripheral cells to express the OPN receptor CD44v6. Relative to β-gal, OPN increased the levels of inflammatory markers, including IL13Rα1, CXCR3, and CD40L. In Ptx-treated OPN KOs, apoptotic TUNEL+ cells surrounding the OPN expression site increased, compared to β-gal. Together, these results show that local OPN expression combined with a peripheral inflammatory stimulus, such as Ptx, may be implicated in the development of brain inflammation and induction of cell death, by driving a molecular pattern characteristic of cytotoxicity. These are characteristics of inflammatory pathologies of the CNS in which OPN upregulation is a hallmark.

Show MeSH
Related in: MedlinePlus