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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

EPR detection of neutrophil degranulation in the presence of nitroxide-labeled elastin (1 mM equivalent nitroxide concentration).(a) EPR signal from 11×104 resting (black circles) or activated (red squares) neutrophils in 0.5 ml versus incubation time at 37°C. (b) EPR signal at five hours incubation at 37°C versus the number of resting (black circles) or activated (red squares) neutrophils.
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pone-0057946-g004: EPR detection of neutrophil degranulation in the presence of nitroxide-labeled elastin (1 mM equivalent nitroxide concentration).(a) EPR signal from 11×104 resting (black circles) or activated (red squares) neutrophils in 0.5 ml versus incubation time at 37°C. (b) EPR signal at five hours incubation at 37°C versus the number of resting (black circles) or activated (red squares) neutrophils.

Mentions: To mimic a situation of inflammation human neutrophils were purified and incubated with the nitroxide-labeled elastin substrate. Degranulation was induced by adding A23187 calcium ionophore. The generated EPR signal intensities were compared to those from samples without ionophore. In figure 4a the EPR signal intensity clearly discriminates the samples with induced neutrophil degranulation from the samples with resting neutrophils at all times of observation. At each time point a faint signal increase without ionophore could be observed. This can easily be explained by some spontaneous cell death over time which triggers the release of granules. As seen in figure 4b at a given time of observation the EPR signal is strongly correlated to the number of neutrophils per well. Again, in the samples without ionophore spontaneous cell death generates a detectable signal however easily discriminated from the one in induced samples.


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)

EPR detection of neutrophil degranulation in the presence of nitroxide-labeled elastin (1 mM equivalent nitroxide concentration).(a) EPR signal from 11×104 resting (black circles) or activated (red squares) neutrophils in 0.5 ml versus incubation time at 37°C. (b) EPR signal at five hours incubation at 37°C versus the number of resting (black circles) or activated (red squares) neutrophils.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0057946-g004: EPR detection of neutrophil degranulation in the presence of nitroxide-labeled elastin (1 mM equivalent nitroxide concentration).(a) EPR signal from 11×104 resting (black circles) or activated (red squares) neutrophils in 0.5 ml versus incubation time at 37°C. (b) EPR signal at five hours incubation at 37°C versus the number of resting (black circles) or activated (red squares) neutrophils.
Mentions: To mimic a situation of inflammation human neutrophils were purified and incubated with the nitroxide-labeled elastin substrate. Degranulation was induced by adding A23187 calcium ionophore. The generated EPR signal intensities were compared to those from samples without ionophore. In figure 4a the EPR signal intensity clearly discriminates the samples with induced neutrophil degranulation from the samples with resting neutrophils at all times of observation. At each time point a faint signal increase without ionophore could be observed. This can easily be explained by some spontaneous cell death over time which triggers the release of granules. As seen in figure 4b at a given time of observation the EPR signal is strongly correlated to the number of neutrophils per well. Again, in the samples without ionophore spontaneous cell death generates a detectable signal however easily discriminated from the one in induced samples.

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