Wednesday, 12 July 2017

Imaging B cells

James ML, Hoehne A, Mayer AT, Lechtenberg K, Moreno M, Gowrishankar G, Ilovich O, Natarajan A, Johnson EM, Nguyen J, Quach L, Han M, Buckwalter M, Chandra S, Gambhir SS. Imaging B cells in a mouse model of multiple sclerosis using 64Cu-Rituximab-PET. J Nucl Med. 2017 Jul 7. pii: jnumed.117.189597. doi: 10.2967/jnumed.117.189597. [Epub ahead of print]

B lymphocytes are a key pathological feature of multiple sclerosis (MS), and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to non-invasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here we evaluated 64Cu-Rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using positron emission tomography (PET). 
Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of Myelin Oligodendrocyte Glycoprotein fragment 1-125 (MOG1-125) emulsified in complete Freund's adjuvant. Control mice received complete Freund's adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19h following 64Cu- (Radioactive copper sixty four) Rituximab administration. Mice were perfused and sacrificed after final PET scan, and radioactivity in dissected tissues was measured with a gamma-counter. CNS tissues from these mice were immunostained to quantify B cells or further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice compared to controls at all evaluated time points (e.g., 1h post-injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 %ID/g, p<0.05). 64Cu-Rituximab-PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice compared to 1.25±0.08 and 2.24±0.11%ID/g for controls, p<0.05 for all regions except striatum and thalamus at 1h post-injection. Similarly, ex vivo bio-distribution results revealed notably higher 64Cu-Rituximab uptake in brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased 64Cu-Rituximab uptake in CNS tissues corresponded with elevated B cells. 
Conclusion: B cells can be detected in the CNS of EAE mice using 64Cu-Rituximab-PET. Results from these studies warrant further investigation of 64Cu-Rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.
                         Note the red in the spinal cord (White Arrow)

As we enter the age of the B cells, we would like to assess the effects of treatments on B cells. This is a study in mice and uses a radioactive version of rituximab to do this. In EAE they can pick up B cells in mice with EAE. This was easy peasey, but can this approach be used in humans.

In the animals, they are giving their imaging agents at a time when they will get into the CNS. The question is what happens when there are no focal lesions one images the penetration of antibody will not be great. It's a start.

14 comments:

  1. You know (i know ) that rituxan does not penetrate well in the cns

    So how its possible that those red dost apear in the spinal cord? Are they debrys from dying b cells killed by anti cd20?
    If rituxan would penetrate more we should see more vivid spots?
    Also if you took the same aproach but targeting T cell (i know you dont like it) could we see the same paterns in the cns?

    Thanks
    Luis

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    1. I agree about penetration in humans but in the way used in the mice the whole spinal cord behaves like a lesion and it is easy to get significant amounts of antibody into the spinal cord irrespective of the specificity.

      But is not being used how it would be in humans.

      Could it be dead b cells yes, could it be debris eaten by macrophages. I would say less too.

      Should it be red dots I would say it should be but the technology can't pick up single cells but if you do histology you get B cell rich lesions.

      Who T cell imaging be better. It should be as there are more T cells than b cells in the cord.EAE is a t cell disease.

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  2. In case you did not see MD-- “B-cells from patients with multiple sclerosis induce cell death via apoptosis in neurons in vitro,” was published in the Journal of Neuroimmunology.

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    1. Thanks I'll have a look it would be good to link b cells to oligodendrocyte other than via antibodies.

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  3. Not the original, just summary and comments from authors:

    https://multiplesclerosisnewstoday.com/2017/07/10/ms-study-links-toxic-b-cell-secretions-to-neuron-cell-deaths/

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  4. Thank you for all you do. I read this today in the NYT, could something like this work for those of us with MS?

    A Food and Drug Administration panel opened a new era in medicine on Wednesday, unanimously recommending that the agency approve the first-ever treatment that genetically alters a patient’s own cells to fight cancer, transforming them into what scientists call “a living drug” that powerfully bolsters the immune system to shut down the disease.

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    1. yes it could happen, the mantra in the accademic work has been personalised medicine but this form of bespoke treatment will be expensive, just like prof penders treatment would be if it were being sold.

      The problem is if the people get it wrong and you have craeated something that can't be stopped.

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  5. I read part of the paper and wondered if, for example, and for a reason not yet known, a virus could hide in oligodendrocyte progenitor cells, and perhaps secrete some substance, a protein, that would cause the OPCs to stop migrating to where they would have been recruited and this would cause them not to mature into oligodendrocytes proper?
    That is, the virus might not even cause the disease but could worsen the disease, the demyelination in those who were infected with it, since it would prevent the maturing of the OPCs?

    Thoughts...

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    1. @Cinara and MD. Thought you may be interested:

      https://medicalxpress.com/news/2017-07-hidden-herpes-virus-key-role.html

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    2. Thanks, HHV-6 was come in an out of fashion.

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    3. Thank you!!!

      I'll read this paper o//

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