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Overhauser-enhanced MRI of elastase activity from in vitro human neutrophil degranulation.

Parzy E, Bouchaud V, Massot P, Voisin P, Koonjoo N, Moncelet D, Franconi JM, Thiaudière E, Mellet P - PLoS ONE (2013)

Bottom Line: However several diseases would benefit from an imaging technique able to specifically detect biochemical alterations.The sensitivity is sufficient to generate contrasted images of the degranulation of neutrophils induced by a calcium ionophore from 2×10(4) cells per milliliter, well under the physiological neutrophils concentrations.It also provides a long-expected method to monitor anti-protease treatments efficiency and help pharmaceutical research.

View Article: PubMed Central - PubMed

Affiliation: CRMSB, UMR 5536, University Bordeaux Segalen, CNRS, Bordeaux, France.

ABSTRACT

Background: Magnetic resonance imaging can reveal exquisite anatomical details. However several diseases would benefit from an imaging technique able to specifically detect biochemical alterations. In this context protease activity imaging is one of the most promising areas of research.

Methodology/principal findings: We designed an elastase substrate by grafting stable nitroxide free radicals on soluble elastin. This substrate generates a high Overhauser magnetic resonance imaging (OMRI) contrast upon digestion by the target proteases through the modulation of its rotational correlation time. The sensitivity is sufficient to generate contrasted images of the degranulation of neutrophils induced by a calcium ionophore from 2×10(4) cells per milliliter, well under the physiological neutrophils concentrations.

Conclusions/significance: These ex-vivo experiments give evidence that OMRI is suitable for imaging elastase activity from neutrophil degranulation. Provided that a fast protease-substrate is used these results open the door to better diagnoses of a number of important pathologies (cystic fibrosis, inflammation, pancreatitis) by OMRI or Electron Paramagnetic Resonance Imaging in vivo. It also provides a long-expected method to monitor anti-protease treatments efficiency and help pharmaceutical research.

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Related in: MedlinePlus

OMRI signal from increasing concentrations of native (black circles) or HNE-digested (red squares) nitroxide-labeled elastin.Complete elastin digestion was carried out during 24 hours with 50 nM HNE at 37°C.
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pone-0057946-g003: OMRI signal from increasing concentrations of native (black circles) or HNE-digested (red squares) nitroxide-labeled elastin.Complete elastin digestion was carried out during 24 hours with 50 nM HNE at 37°C.

Mentions: The aim of this work is to generate high contrast images in the presence of elastase activity using Overhauser-enhanced MRI. Various concentrations of nitroxide-labeled elastin, corresponding to a range of 0.07 to 0.7 mM nitroxides, were thus incubated for 24 hours in the presence or absence of human neutrophil elastase. Figure 3 shows that HNE produces a 3 to 5.6 times increase of the NMR signal due to the Overhauser effect for the whole range of concentrations. At 0.07 mM nitroxide concentration the signal is readily 3 times higher in the presence of HNE. Thus nitroxide-labeled elastin is able to generate high contrast images in the presence of HNE at low nitroxide concentration.


Overhauser-enhanced MRI of elastase activity from in vitro human neutrophil degranulation.

Parzy E, Bouchaud V, Massot P, Voisin P, Koonjoo N, Moncelet D, Franconi JM, Thiaudière E, Mellet P - PLoS ONE (2013)

OMRI signal from increasing concentrations of native (black circles) or HNE-digested (red squares) nitroxide-labeled elastin.Complete elastin digestion was carried out during 24 hours with 50 nM HNE at 37°C.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585236&req=5

pone-0057946-g003: OMRI signal from increasing concentrations of native (black circles) or HNE-digested (red squares) nitroxide-labeled elastin.Complete elastin digestion was carried out during 24 hours with 50 nM HNE at 37°C.
Mentions: The aim of this work is to generate high contrast images in the presence of elastase activity using Overhauser-enhanced MRI. Various concentrations of nitroxide-labeled elastin, corresponding to a range of 0.07 to 0.7 mM nitroxides, were thus incubated for 24 hours in the presence or absence of human neutrophil elastase. Figure 3 shows that HNE produces a 3 to 5.6 times increase of the NMR signal due to the Overhauser effect for the whole range of concentrations. At 0.07 mM nitroxide concentration the signal is readily 3 times higher in the presence of HNE. Thus nitroxide-labeled elastin is able to generate high contrast images in the presence of HNE at low nitroxide concentration.

Bottom Line: However several diseases would benefit from an imaging technique able to specifically detect biochemical alterations.The sensitivity is sufficient to generate contrasted images of the degranulation of neutrophils induced by a calcium ionophore from 2×10(4) cells per milliliter, well under the physiological neutrophils concentrations.It also provides a long-expected method to monitor anti-protease treatments efficiency and help pharmaceutical research.

View Article: PubMed Central - PubMed

Affiliation: CRMSB, UMR 5536, University Bordeaux Segalen, CNRS, Bordeaux, France.

ABSTRACT

Background: Magnetic resonance imaging can reveal exquisite anatomical details. However several diseases would benefit from an imaging technique able to specifically detect biochemical alterations. In this context protease activity imaging is one of the most promising areas of research.

Methodology/principal findings: We designed an elastase substrate by grafting stable nitroxide free radicals on soluble elastin. This substrate generates a high Overhauser magnetic resonance imaging (OMRI) contrast upon digestion by the target proteases through the modulation of its rotational correlation time. The sensitivity is sufficient to generate contrasted images of the degranulation of neutrophils induced by a calcium ionophore from 2×10(4) cells per milliliter, well under the physiological neutrophils concentrations.

Conclusions/significance: These ex-vivo experiments give evidence that OMRI is suitable for imaging elastase activity from neutrophil degranulation. Provided that a fast protease-substrate is used these results open the door to better diagnoses of a number of important pathologies (cystic fibrosis, inflammation, pancreatitis) by OMRI or Electron Paramagnetic Resonance Imaging in vivo. It also provides a long-expected method to monitor anti-protease treatments efficiency and help pharmaceutical research.

Show MeSH
Related in: MedlinePlus