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In vivo, multimodal imaging of B cell distribution and response to antibody immunotherapy in mice.

Thorek DL, Tsao PY, Arora V, Zhou L, Eisenberg RA, Tsourkas A - PLoS ONE (2010)

Bottom Line: Cellular imaging of the targeted population in vivo may provide significant insight towards effective therapy and a greater understanding of underlying disease mechanics.These data suggest that in vivo imaging can be used to follow B cell dynamics, but that the labeling method will need to be carefully chosen.SPIO labeling for tracking purposes, generally thought to be benign, appears to interfere with B cell functions and requires further examination.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.

ABSTRACT

Background: B cell depletion immunotherapy has been successfully employed to treat non-Hodgkin's lymphoma. In recent years, increasing attention has been directed towards also using B-cell depletion therapy as a treatment option in autoimmune disorders. However, it appears that the further development of these approaches will depend on a methodology to determine the relation of B-cell depletion to clinical response and how individual patients should be dosed. Thus far, patients have generally been followed by quantification of peripheral blood B cells, but it is not apparent that this measurement accurately reflects systemic B cell dynamics.

Methodology/principal findings: Cellular imaging of the targeted population in vivo may provide significant insight towards effective therapy and a greater understanding of underlying disease mechanics. Superparamagnetic iron oxide (SPIO) nanoparticles in concert with near infrared (NIR) fluorescent dyes were used to label and track primary C57BL/6 B cells. Following antibody mediated B cell depletion (anti-CD79), NIR-only labeled cells were expeditiously cleared from the circulation and spleen. Interestingly, B cells labeled with both SPIO and NIR were not depleted in the spleen.

Conclusions/significance: Whole body fluorescent tracking of B cells enabled noninvasive, longitudinal imaging of both the distribution and subsequent depletion of B lymphocytes in the spleen. Quantification of depletion revealed a greater than 40% decrease in splenic fluorescent signal-to-background ratio in antibody treated versus control mice. These data suggest that in vivo imaging can be used to follow B cell dynamics, but that the labeling method will need to be carefully chosen. SPIO labeling for tracking purposes, generally thought to be benign, appears to interfere with B cell functions and requires further examination.

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Fluorescent images of contrast-labeled B cells in excised organs.A, Representative fluorescent images of the excised heart (H), lung (L), spleen (S), and liver (L) from animals injected with contrast labeled B cells. The B cells were either labeled with SPIO and NIR815 (groups i and ii) or just NIR815 (groups iii and iv), as indicated. Animals were either treated with PBS (groups i and iii) or anti-CD79 antibodies (ii and iv) following imaging on day 1. One animal per group was sacrificed at each time point, immediately following MR and in vivo fluorescent imaging. B and C, The mean fluorescence intensity (MFI) of the spleen, normalized to day 1 values for each group, is plotted for the length of the experiment. A gradual loss of signal from the spleen is seen in all groups, save the rapid decrease following treatment of NIR815-only labeled cells (iv).
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pone-0010655-g004: Fluorescent images of contrast-labeled B cells in excised organs.A, Representative fluorescent images of the excised heart (H), lung (L), spleen (S), and liver (L) from animals injected with contrast labeled B cells. The B cells were either labeled with SPIO and NIR815 (groups i and ii) or just NIR815 (groups iii and iv), as indicated. Animals were either treated with PBS (groups i and iii) or anti-CD79 antibodies (ii and iv) following imaging on day 1. One animal per group was sacrificed at each time point, immediately following MR and in vivo fluorescent imaging. B and C, The mean fluorescence intensity (MFI) of the spleen, normalized to day 1 values for each group, is plotted for the length of the experiment. A gradual loss of signal from the spleen is seen in all groups, save the rapid decrease following treatment of NIR815-only labeled cells (iv).

Mentions: Fluorescent images of the excised liver, lungs, heart and spleen were acquired from a single animal from each group, at each time point (Fig. 4A). The distribution of B cells as determined by ex vivo fluorescence imaging confirmed that homing to the spleen was rapid. One day after B cell injection a strong signal was observed in the spleen. Significantly less fluorescence was observed in the liver and little to no signal was detectable in the heart or lungs. Consistent with live animals imaging studies, SPIO seemed to interfere with the ability to deplete the transferred cells as there was no significant difference between control and treated mice (Fig. 4B). However, in the absence of SPIO, B cell depletion could be readily observed through the loss of NIR815 fluorescence in the spleen. Quantitative analysis revealed a ∼80% reduction in the mean fluorescence intensity (MFI) of NIR815 within the spleen only two days after the administration of anti-CD79 antibodies (Fig. 4C). Mice treated with PBS only exhibited a ∼35% reduction in MFI at the same time point.


In vivo, multimodal imaging of B cell distribution and response to antibody immunotherapy in mice.

Thorek DL, Tsao PY, Arora V, Zhou L, Eisenberg RA, Tsourkas A - PLoS ONE (2010)

Fluorescent images of contrast-labeled B cells in excised organs.A, Representative fluorescent images of the excised heart (H), lung (L), spleen (S), and liver (L) from animals injected with contrast labeled B cells. The B cells were either labeled with SPIO and NIR815 (groups i and ii) or just NIR815 (groups iii and iv), as indicated. Animals were either treated with PBS (groups i and iii) or anti-CD79 antibodies (ii and iv) following imaging on day 1. One animal per group was sacrificed at each time point, immediately following MR and in vivo fluorescent imaging. B and C, The mean fluorescence intensity (MFI) of the spleen, normalized to day 1 values for each group, is plotted for the length of the experiment. A gradual loss of signal from the spleen is seen in all groups, save the rapid decrease following treatment of NIR815-only labeled cells (iv).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2871797&req=5

pone-0010655-g004: Fluorescent images of contrast-labeled B cells in excised organs.A, Representative fluorescent images of the excised heart (H), lung (L), spleen (S), and liver (L) from animals injected with contrast labeled B cells. The B cells were either labeled with SPIO and NIR815 (groups i and ii) or just NIR815 (groups iii and iv), as indicated. Animals were either treated with PBS (groups i and iii) or anti-CD79 antibodies (ii and iv) following imaging on day 1. One animal per group was sacrificed at each time point, immediately following MR and in vivo fluorescent imaging. B and C, The mean fluorescence intensity (MFI) of the spleen, normalized to day 1 values for each group, is plotted for the length of the experiment. A gradual loss of signal from the spleen is seen in all groups, save the rapid decrease following treatment of NIR815-only labeled cells (iv).
Mentions: Fluorescent images of the excised liver, lungs, heart and spleen were acquired from a single animal from each group, at each time point (Fig. 4A). The distribution of B cells as determined by ex vivo fluorescence imaging confirmed that homing to the spleen was rapid. One day after B cell injection a strong signal was observed in the spleen. Significantly less fluorescence was observed in the liver and little to no signal was detectable in the heart or lungs. Consistent with live animals imaging studies, SPIO seemed to interfere with the ability to deplete the transferred cells as there was no significant difference between control and treated mice (Fig. 4B). However, in the absence of SPIO, B cell depletion could be readily observed through the loss of NIR815 fluorescence in the spleen. Quantitative analysis revealed a ∼80% reduction in the mean fluorescence intensity (MFI) of NIR815 within the spleen only two days after the administration of anti-CD79 antibodies (Fig. 4C). Mice treated with PBS only exhibited a ∼35% reduction in MFI at the same time point.

Bottom Line: Cellular imaging of the targeted population in vivo may provide significant insight towards effective therapy and a greater understanding of underlying disease mechanics.These data suggest that in vivo imaging can be used to follow B cell dynamics, but that the labeling method will need to be carefully chosen.SPIO labeling for tracking purposes, generally thought to be benign, appears to interfere with B cell functions and requires further examination.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.

ABSTRACT

Background: B cell depletion immunotherapy has been successfully employed to treat non-Hodgkin's lymphoma. In recent years, increasing attention has been directed towards also using B-cell depletion therapy as a treatment option in autoimmune disorders. However, it appears that the further development of these approaches will depend on a methodology to determine the relation of B-cell depletion to clinical response and how individual patients should be dosed. Thus far, patients have generally been followed by quantification of peripheral blood B cells, but it is not apparent that this measurement accurately reflects systemic B cell dynamics.

Methodology/principal findings: Cellular imaging of the targeted population in vivo may provide significant insight towards effective therapy and a greater understanding of underlying disease mechanics. Superparamagnetic iron oxide (SPIO) nanoparticles in concert with near infrared (NIR) fluorescent dyes were used to label and track primary C57BL/6 B cells. Following antibody mediated B cell depletion (anti-CD79), NIR-only labeled cells were expeditiously cleared from the circulation and spleen. Interestingly, B cells labeled with both SPIO and NIR were not depleted in the spleen.

Conclusions/significance: Whole body fluorescent tracking of B cells enabled noninvasive, longitudinal imaging of both the distribution and subsequent depletion of B lymphocytes in the spleen. Quantification of depletion revealed a greater than 40% decrease in splenic fluorescent signal-to-background ratio in antibody treated versus control mice. These data suggest that in vivo imaging can be used to follow B cell dynamics, but that the labeling method will need to be carefully chosen. SPIO labeling for tracking purposes, generally thought to be benign, appears to interfere with B cell functions and requires further examination.

Show MeSH
Related in: MedlinePlus