I have recently diagnosed a rare histotype of CJD in which I noted clearly many cortical PrP intra-glial inclusions. As far as I know, published data only describe these findings in experimental prion disease performed in sheeps...
Adriano Aguzzi has shown (among others) that glia cells can replicate prions. Hence I wouldn't be surprised to also see it in a CJD patient (even if it is a rare case). The fact that an experimental transmission model has also shown this type of deposit just strengthens this interpretation.
What type of staining did you use to find those intra-glial inclusions? Depending on the type of procedure / conditions it'll also tell you something about the state of PrP in those inclusions.
Many thanks for your answer.
We use Anti-Prion Protein 109-112, clone 3F4. (MILLIPORE), following the manufacture instructions.
3F4 is a very good antibody and it is widely used. Hence, most reviewers will have heard of it or used it themselves.
I guess your samples are fixed (formaldehyde or glutaraldehyde?). Do you use an epitope recovery method (e.g. hydrolytic autoclaving)?
Yes, our samples are always fixed in formaldehyde and then, we also use the Heat Induced Epitope Retrieval (HIER) technique with a Citrate Buffer Method. However, in this case we clearly observed intra-glial PrP deposits in the cortex in association with plaque-type and granular-type extracellular deposits. I will continue reviewing the literature. Many thanks for your help.
Alright, it is good that you use the epitope retrieval method. Strictly speaking 3F4 does NOT recognize PrPSc, but only PrPC and other misfolded forms of PrP. Of course, after fixation and antigen retrieval a fair amount of the PrPSc became unfolded and accessible to 3F4.
Disease assocaited intraglial PrP accumulations are found in all of the animal TSE (CWD, BSE ,Scrapie) and in their corresponding mouse models. I have no direct experience of CJD but I would be surprised if there are not some intraglial diease associated PrP accumulations in this prion disease also.
These intracellular PrP deposits (in animal TSEs) are N terminally truncated and are found in lysosomes. Extracellular amyloid and membrane PrPd (the plaque type and ganular accumulations you describe) are mostly full length diesase assocated protein. Hence most intracellular depostis are in the process of being digested. Have you tried labelling with N terminal antibodies (such as 12B2) to see if the intracelluar deposits remain or are lost when compared with the magnitude of plaque labelling?
That said, as Holger has written , there is plenty of evidence from a number of studies (including that of Bruce Chesebro's TG3 model in which PrP is expressed only on astrocytes,) that glial cells can replicate prions also.
As far as I know, there is no evidence of intracellular inclusions for PrP in human brains with CJD published in referents neuropathological textbooks and english literature. We are double checking PrP immunohistochemistry in this brain. Many thanks for your answer.
I do not find strange PrP observed in glia and this does not surprise me much But I appreciate that question because it makes me think. On Monday I'll see a new case of prion disease and I'll answer with more data.
Many thanks dear Teresa for your answer. We are looking forward to hearing from you every data you can add. We are deeply studying the brain, and we also pretend to present the case on the next Iberian Congress of Prions, that will take place in Zaragoza. We are also aware that Dr.Martin Jeffrey will be there so, we hope to discuss this finding there.
After more than 4 years developing further analyses on brain tissue using different methods, we have eventually published the case report:
Neuropathology. 2018 Aug 19. doi: 10.1111/neup.12505. [Epub ahead of print] Sporadic Creutzfeldt-Jakob disease with glial PrPRes nuclear and perinuclear immunoreactivity.
Fernández-Vega I, Díaz-Lucena D, Azkune Calle I, Geijo M, Juste RA, Llorens F, Vicente Etxenausia I, Santos-Juanes J, Zarranz Imirizaldu JJ, Ferrer I
I am very pleased to Dr. Isidro Ferrer and it´s laboratory team for helping me with this interesting case.
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