Oct. 27, 2011 Medical researchers at the University of Alberta have discovered a potential new drug target for multiple sclerosis that could prevent the physical disability associated with the disease.
In the first phase of MS, those with the condition have inflammation of their brain cells, resulting in continuous cycles of inflammation attacks and recovery periods. In the second phase of the disease, the inflammation isn't as severe, but this is the stage where physical disability sets in due to the effects of substantial brain cells being killed in the first phase of the disease.
When immune cells become active due to inflammation, they can pass the blood brain barrier and enter the central nervous system. Some of these activated immune cells secrete a molecule, known as granzyme B, which can get inside neurons and wreak havoc, ultimately causing brain cell death. Granzyme B is found in MS brain lesions, especially in the early stages of inflammation. This molecule can get into brain cells through a "gatekeeper," known as receptor M6PR.
Researchers with the Faculty of Medicine & Dentistry discovered in lab experiments that if they prevent this granzyme B from entering neurons, "we can also prevent the killing of neurons," says principal investigator Fabrizio Giuliani, whose work was recently published in the peer-reviewed publication The Journal of Immunology.
"It is this loss of brain cells in the long term which induces disability in those with MS," he says. "This is a new drug target for MS that is specific for the neurodegenerative processes following inflammation. A new drug treatment should address this long-term loss of brain cells."
Giuliani, a researcher in the Division of Neurology and a practising neurologist, noted this latest research builds on previous findings by his colleagues within the faculty. Medical researcher and co-author Chris Bleackley made an earlier discovery about how granzyme B enters target cells through the receptor M6PR, while another faculty researcher discovered that the M6PR receptor is found mostly in neurons.
"We were just connecting the dots and said, 'OK, if this receptor is expressed in neurons specifically and not expressed in other cells, is it possible that this is the mechanism that allows this granzyme B to get into human neurons and start killing brain cells?' What we found is yes, this 'death' receptor allows this specific molecule to get in and that if you block the receptor, you also block the neurotoxic effect in neurons. This is an excellent example about collaboration with other researchers and translational research."
Many existing MS treatments primarily target brain inflammation, which is very effective in the first phase of the disease but not as helpful once patients reach the second phase. Giuliani says what is needed are new medications that can either repair inflamed brain cells or prevent brain degeneration in the first place. He says this new drug target could do just that, by preventing brain cell death in the early stages of the disease.
With this new drug target, Giuliani adds that only a specific function of a cell would be blocked, not multiple functions of a cell. Many medications on the market block multiple functions of a specific type of cell. "We are blocking a specific function, not multiple pathways and eventually this strategy could reduce the side effects of new drugs."
Giuliani and his fellow researchers are continuing their research in this area.
This research was supported through funding by the MS Society of Canada, the Canadian Institutes of Health Research, Alberta Innovates-Health Solutions and the University of Alberta Hospital Foundation.
Julia Daniluck, an Edmontonian who has MS, said the research findings were encouraging. Daniluk was diagnosed with MS nine years ago when she was just 19-years-old. She was having mobility issues after returning home from her job as a dancer on a cruise ship. When she went to the doctor and underwent various tests, she was diagnosed with MS. She is now studying marketing through the University of Lethbridge and is engaged to be married. Just this last weekend, a fundraising team she organized raised $100,000 for the MS Society.
"To me, I know that there's still so many unknowns about MS and this is just one more piece of the puzzle for us to truly gain an understanding about the cause of MS and the progression and why things happen the way they do…
"For the future, you have to start somewhere to make these discoveries. The amount of work these researchers put into making these discoveries is just amazing."
Darrel Gregory, a spokesperson for the MS Society of Canada -- Alberta & NWT Division -- said the organization was excited about Giuliani's discovery. In Alberta, more than 11,000 people have MS. Across the country, between 55,000 -- 75,000 people live with the disease.
"It means a great deal to us because I think it offers hope to everybody who lives with MS; hope for a potential treatment and possibly a cure at one point. I think that if we can lessen the physical disability that people live with, it will go a long way to helping improve quality of life for people who live with MS."
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The above story is based on materials provided by University of Alberta Faculty of Medicine & Dentistry. The original article was written by Raquel Maurier.
- Y. Haile, K. C. Simmen, D. Pasichnyk, N. Touret, T. Simmen, J.-Q. Lu, R. C. Bleackley, F. Giuliani. Granule-Derived Granzyme B Mediates the Vulnerability of Human Neurons to T Cell-Induced Neurotoxicity. The Journal of Immunology, 2011; 187 (9): 4861 DOI: 10.4049/jimmunol.1100943
Note: If no author is given, the source is cited instead.