Fighting a lion-sized disease through a lamb
GM1 sheep have proven exceptionally valuable in the fight against Neurologic Diseases
October 20, 2017
Huntington's Disease is a dirty thief. It robs the people it strikes of their minds and bodies in the form of muscle coordination loss, abnormal writhing referred to as chorea, and leads to both cognitive decline and psychiatric problems. For those who are stricken, there appears to be growing hope in a raw material with four legs and covered in wool.
For the past 25 years, Larry and Sue Holler from White, S.D., have maintained a genetic line of sheep that have proven exceptionally valuable in the fight against Huntington's Disease.
"Larry actually worked with this genetic line during his PhD research and then when they quit doing research on them, we saw the value in them and purchased them," she said.
These particular sheep are missing an enzyme causing them to accumulate a molecule called GM 1 ganglioside, a molecule all mammals have that is neuroprotective and neuroregenerative.
At the time the Hollers purchased the flock, there was an Italian company collecting GM 1 ganglioside, which, despite years of effort, has proven difficult to synthesize. It was in use for treating peripheral neuropathy in Europe and in U.S. clinical trials for Parkinson's and spinal cord injury. The notable difference was this Italian company's sourcing was from slaughterhouses in England using bovine brain tissue. Following the Mad Cow Disease, or encephalopathy, outbreak the Food and Drug Administration ended the use of animal tissues without traceability.
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With the door to bovine tissue closed and decades of unsuccessfully attempting to synthesize the complicated molecule, the research came full circle back to animal products. The individuals in the Holler's flock have either been identified as carriers of GM 1 gangliosidosis, making them excellent breeding stock, or have tested positive for gangliosidosis. Lambs that have tested positive for the disease accumulate the GM 1 ganglioside molecule at a rate Holler said is 40 times the rate at which the cattle previously accumulated. These lambs are sent to the Holler's facility and fed to harvest.
"We harvest them at four to six months when we think their GM 1 is probably at its peak," she said. "They go through a butchering process and we keep the set of tissues. Brain and spinal cord are especially rich in ganglioside and we've also found that liver has about the same amount of GM 1 as the brain."
The Hollers are currently working with Travis Hoffman, PhD, at North Dakota State University, and Keith Underwood, PhD, at South Dakota State University looking at any differences in meat quality and safety between the gangliosidosis lambs and normal commodity lambs.
"Preliminary data that Larry did quite a while ago suggests that the molecule accumulates in the nervous tissue and not the meat," he said. This research was funded through the National Sheep Industry Improvement Center. Holler said they anticipate the GM 1 lamb's meat composition will be the same as commodity-type lambs.
The production methods of the GM 1 lambs are the same as a typical flock but it is certainly not a trait herders would desire in their flocks. It is a single point mutation, not typical in most flocks. Outside of the cooperating flocks the Hollers work with, they are unaware of any other affected flocks.
"It is a higher level of sheep production," she said. "Recordkeeping is important. We've also determined these (GM 1) lambs don't compete with other lambs very well. At first, they're like any lamb but as that GM 1 ganglioside accumulates in their brain, it starts to affect them."
Affected lambs don't compete well with other lambs in terms of nursing or at the feed bunk so the GM 1 lambs require extra management to ensure their success. Blood tests can be used to identify GM 1 lambs and they can be segregated at weaning and managed more intensely. GM 1 lambs, she said, present normally at birth until approximately 3 months of age at which point they begin to fall behind their peers. This is the point at which the Hollers receive the GM 1 lambs from the 17 cooperating flocks in the region, allowing them to continue their studies on GM 1 gangliosidosis.
The first research paper on the tie between Huntington's disease and GM 1 ganglioside came out in 2012 with a second paper being released just this month with compelling results in mice.
"They call HD the cruelest disease known to man," she said. "There's no other disease like it. It steals both your mind and your body in a long, awful progression."
In the course of the years of research, several Huntington's families came forward to the Hollers and asked how they could help and The Shepherd's Gift GM 1 for HD nonprofit was formed to secure funding needed to move forward with research.
"One of the family members of the founding board just passed away at 44," she said. "She had been in a nursing home for five years and on disability for eight years."
This particular woman was a social worker, a job Holler said she loved, but her career and life was cut short as a result of Huntington's. Her family continues to work closely with The Shepherd's Gift and the Hollers.
"If we had all the money we needed," she said. "We could probably be in clinical trials at the end of 2018."
As the Hollers and the families behind The Shepherd's Gift continue to raise money through private donations, events like the the Shepherd's Shuffle, a 1 mile walk and 5K race, there are a number of exciting developments. The study now has a dedicated researcher in Sioux Falls at the University Center who is working on pharmaceutical grade GM 1. The group has also recently connected with a researcher at Central Michigan University who was actually funded by the Italian company that originally used bovine GM 1 nearly 30 years ago. He now has ovine GM 1 and is able to continue his work required by the FDA in preparation to move into clinical trials.
As the research moves forward, it is truly lamb producer families helping Huntington's families and working to improve their quality of life and fighting a lion-sized disease through a lamb.
— Spencer Gabel is a freelance writer from Wiggins, Colo., where she and her family raise cattle and show goats. She can be reached at firstname.lastname@example.org or on Facebook at Rachel Spencer Media.
To find out more about The Shepherd’s Gift go to http://www.theshepherdsgift.org.