While we were discussing the paper mentioning pannocytes in class, I realized I had no clue what those cells were. Here are some facts about these cell types based on an article I skimmed:
- These cells are found at the sites of RA cartilage injury but not in osteoarthritis cartilage.
- Morphologically, they are rhomboid in shape while fibroblasts are bipolar and chondrocytes are spherical.
- Chondrocytes are short lived (6-8 divisions) but pannocytes have a much longer life span (25 divisions)
- Both pannocytes and chondrocytes can produce collagenase and stromelysin, both of which are proteases that destroy the extracellular matrix. The kicker: pannocytes live much longer than chondrocytes...
For further info see: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1857892/pdf/amjpathol00027-0336.pdf
-Vinoo
I was right there with you, in class, clueless as to what a pannocyte was. All of these facts are really interesting, and definitely things I was no aware of before.
ReplyDeleteI had a question about one of your points, that you may or may not have read. You shared with us that pannocytes are found at the site of RA cartilage injury but not at osteoarthritis cartilage. Did you read or do you think there is any particular reason for this?
Great facts!
-Heidi
While the paper did not discuss why pannocytes were only found in RA cartilage but I'd imagine it has something to do with the nature of the disease. Completely speculating, but these cell types might only be seen in RA tissue as RA is caused by an autoimmune problem, and these abnormal cells are the somehow involved in the immune response. On the other hand, since OA is mainly due to mechanical issues leading to joint degradation, abnormal cells wouldn't have to present for this problem to arise.
ReplyDeleteI ask that question in class and also did some researchon them. I found this really great paper discussing the nature of pannocytes and it goes a little further into their actions then the various google links. If you are interested you should check it out.
ReplyDelete"Pannocytes under the influence of locally produced cytokines and growth factors, proliferate and express a broad array of proteinases, such as collagenase and stromelysin, that are thought to be directly responsible for the tissue destruction.3 6 Simultaneously, chondrocytes digest the matrix in which they are normally embedded and osteoclasts destroy bone (Zvaifler et al.)" They go on to discuss the various mechanisms of pannocytes in RA. I'm not sure if this article was the first to do so but it aimed to prove that pannocytes did indeed exist seperate from other destructive cells in the synovial fluid during RA.
Zvaifler, N. J., Van, T., Alsalameh, S., Kempis, J. ., Firestein, G. S., & Lotz, M. (January 01, 1997). Pannocytes: Distinctive Cells Found in Rheumatoid Arthritis Articular Cartilage Erosions. The American Journal of Pathology, 150, 3, 1125.
I too was curious about what pannocytes were, and this article really helped illuminate some of the questions I had. Thank you for posting and sharing these interesting facts! The other fact that I found interesting from reading this article was pannocytes only express the mRNA for type I collagen genes but fail to make NO, suggesting that they could be linked to fibroblast like synoviocytes, or since they grow rapidly and have a prolonged life span that they represent chondrocytes at very early stage of development, or that they are chondrocytes that have differentiated. However the paper concludes that pannocytes can clearly be distinguished from FLS and chondrocytes even though they do share some common features. I guess more research is still need to determine what exactly pannocytes are…
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