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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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Longitudinal MR imaging and quantification of contrast-labeled B cells prior to and following B cell depletion therapy.A, Representative axial T2*-weighted images of mice either pre-injection (day 0) or on the indicated days following injection of contrast labeled B cells. Hypointensity of the spleen was noted in animals of the groups given SPIO-loaded B cells (block ended arrow: groups i and ii). Isointense signal was observed on all pre-contrast images and in animals injected with NIR815-labeled B cells (groups iii and iv). Either PBS or anti-CD79 was administered to each group after imaging on day 1. B, Relative signal intensity (rSI; calculated as the ratio of signal in the spleen to paraspinal muscle) is plotted, normalized to pre-contrast images. For SPIO-labeled B cell groups (i and ii, ▪) a rapid and pronounced decrease in rSI was observed. There was also only limited difference between the normalized rSI of PBS (i, solid line) and anti-CD79 (ii, dashed line) administered groups following treatment. There was no significant change in spleen signal for groups devoid of SPIO, after B cell injection (iii and iv, ○). A gradual decrease in normalized rSI was seen in the anti-CD79 treated group (iv, dashed line). C, Although SPIO-labeled B cells were not depleted following the administration of anti-CD79 antibodies as detected by MR, the number of peripheral B cells were reduced compared to PBS-treated controls. A similar depletion profile was seen for the NIR-only labeled B cell groups.
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pone-0010655-g002: Longitudinal MR imaging and quantification of contrast-labeled B cells prior to and following B cell depletion therapy.A, Representative axial T2*-weighted images of mice either pre-injection (day 0) or on the indicated days following injection of contrast labeled B cells. Hypointensity of the spleen was noted in animals of the groups given SPIO-loaded B cells (block ended arrow: groups i and ii). Isointense signal was observed on all pre-contrast images and in animals injected with NIR815-labeled B cells (groups iii and iv). Either PBS or anti-CD79 was administered to each group after imaging on day 1. B, Relative signal intensity (rSI; calculated as the ratio of signal in the spleen to paraspinal muscle) is plotted, normalized to pre-contrast images. For SPIO-labeled B cell groups (i and ii, ▪) a rapid and pronounced decrease in rSI was observed. There was also only limited difference between the normalized rSI of PBS (i, solid line) and anti-CD79 (ii, dashed line) administered groups following treatment. There was no significant change in spleen signal for groups devoid of SPIO, after B cell injection (iii and iv, ○). A gradual decrease in normalized rSI was seen in the anti-CD79 treated group (iv, dashed line). C, Although SPIO-labeled B cells were not depleted following the administration of anti-CD79 antibodies as detected by MR, the number of peripheral B cells were reduced compared to PBS-treated controls. A similar depletion profile was seen for the NIR-only labeled B cell groups.

Mentions: MR imaging was used longitudinally to monitor the trafficking and biodistribution of B cells labeled with both SPIO and NIR815 or NIR815 only (i.e. SPIO-free). One day following the administration of SPIO-labeled B cells, the spleen appeared darker on T2*-weighted images (Fig. 2A, row i). This hypointensity is consistent with the accumulation of SPIO. The spleen remained hypointense for several days, but gradually returned to near baseline over the course of two weeks. Animals that were treated with anti-CD79 antibody one day following the administration of SPIO-labeled B cells (Fig. 2A, row ii) exhibited a similar pattern of contrast enhancement as the control (PBS-treated) animals over the course of the study.


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)

Longitudinal MR imaging and quantification of contrast-labeled B cells prior to and following B cell depletion therapy.A, Representative axial T2*-weighted images of mice either pre-injection (day 0) or on the indicated days following injection of contrast labeled B cells. Hypointensity of the spleen was noted in animals of the groups given SPIO-loaded B cells (block ended arrow: groups i and ii). Isointense signal was observed on all pre-contrast images and in animals injected with NIR815-labeled B cells (groups iii and iv). Either PBS or anti-CD79 was administered to each group after imaging on day 1. B, Relative signal intensity (rSI; calculated as the ratio of signal in the spleen to paraspinal muscle) is plotted, normalized to pre-contrast images. For SPIO-labeled B cell groups (i and ii, ▪) a rapid and pronounced decrease in rSI was observed. There was also only limited difference between the normalized rSI of PBS (i, solid line) and anti-CD79 (ii, dashed line) administered groups following treatment. There was no significant change in spleen signal for groups devoid of SPIO, after B cell injection (iii and iv, ○). A gradual decrease in normalized rSI was seen in the anti-CD79 treated group (iv, dashed line). C, Although SPIO-labeled B cells were not depleted following the administration of anti-CD79 antibodies as detected by MR, the number of peripheral B cells were reduced compared to PBS-treated controls. A similar depletion profile was seen for the NIR-only labeled B cell groups.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2871797&req=5

pone-0010655-g002: Longitudinal MR imaging and quantification of contrast-labeled B cells prior to and following B cell depletion therapy.A, Representative axial T2*-weighted images of mice either pre-injection (day 0) or on the indicated days following injection of contrast labeled B cells. Hypointensity of the spleen was noted in animals of the groups given SPIO-loaded B cells (block ended arrow: groups i and ii). Isointense signal was observed on all pre-contrast images and in animals injected with NIR815-labeled B cells (groups iii and iv). Either PBS or anti-CD79 was administered to each group after imaging on day 1. B, Relative signal intensity (rSI; calculated as the ratio of signal in the spleen to paraspinal muscle) is plotted, normalized to pre-contrast images. For SPIO-labeled B cell groups (i and ii, ▪) a rapid and pronounced decrease in rSI was observed. There was also only limited difference between the normalized rSI of PBS (i, solid line) and anti-CD79 (ii, dashed line) administered groups following treatment. There was no significant change in spleen signal for groups devoid of SPIO, after B cell injection (iii and iv, ○). A gradual decrease in normalized rSI was seen in the anti-CD79 treated group (iv, dashed line). C, Although SPIO-labeled B cells were not depleted following the administration of anti-CD79 antibodies as detected by MR, the number of peripheral B cells were reduced compared to PBS-treated controls. A similar depletion profile was seen for the NIR-only labeled B cell groups.
Mentions: MR imaging was used longitudinally to monitor the trafficking and biodistribution of B cells labeled with both SPIO and NIR815 or NIR815 only (i.e. SPIO-free). One day following the administration of SPIO-labeled B cells, the spleen appeared darker on T2*-weighted images (Fig. 2A, row i). This hypointensity is consistent with the accumulation of SPIO. The spleen remained hypointense for several days, but gradually returned to near baseline over the course of two weeks. Animals that were treated with anti-CD79 antibody one day following the administration of SPIO-labeled B cells (Fig. 2A, row ii) exhibited a similar pattern of contrast enhancement as the control (PBS-treated) animals over the course of the study.

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