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Fishy tales

Published on 01 November 2011
Source: Arthritis Today

Dr Chissy Hammond

Dr Chrissy Hammond from Bristol University and fishy friends

Zebrafish could hold the key to unlocking the genetic basis of osteoarthritis, while omega-3 oil fish oil has been shown to reduce the symptoms of osteoarthritis. Jane Tadman reports.

Zebrafish – a new approach to osteoarthritis research?

The humble zebrafish could hold the key to helping scientists track down the genes that cause osteoarthritis.

By identifying the genetic mutations that cause skeletal problems in zebrafish, Dr Chrissy Hammond from the Bristol University is hoping to understand the changes that underlie the progression of osteoarthritis in human cartilage and bone.

Zebrafish have been widely used in laboratory investigations to understand human disease since the 1970s. Like humans, the zebrafish has a backbone, and the genes that control the development of its skeleton are very similar to those in humans. These features make the zebrafish a very useful model for studying human diseases of the bones and joints, including osteoarthritis.

Dr Hammond has now been awarded a career development fellowship from Arthritis Research UK of almost £400,000 over five years to pursue this unusual line of work.

“Genetic mapping”

Based at the university department of biochemistry, physiology and pharmacology, she is carrying out a large-scale screening of thousands of zebrafish in a process called “genetic mapping”, looking for genes that may be linked to osteoarthritis. Working with zebrafish will give Dr Hammond a unique opportunity to understand how genetic mutations can cause defects during the development of the bones and joints in “real time” in a living organism – important clues to help us to understand how osteoarthritis develops.

The next step is to look at ways to reverse the defects caused by the genetic mutations by administering a number of experimental drug compounds to the zebrafish. As most of these drugs dissolve in water, a huge number of possible drugs can be screened in this way, quickly and at low cost.

This is the early, first stage of investigation, and any genetic mutations that look promising will be tested in animals that are more closely related to humans, such as rodents. “We’re trying to target research that gives better guidance on possible candidate genes, and what may work and what is not likely to work,” adds Dr Hammond, who did her PhD investigating the way that zebrafishs’ muscles develop.

Zebrafish are see-through

“Not only are zebrafish easy to grow and maintain, they are an ideal system for studying bone development and disease as they are see-through; you can see what’s going on in their skeleton as the cartilage and bone develops. I can actually watch what the cells are doing in the living fish.”

A single zebrafish can lay 200 embryos a week, and Dr Hammond has worked with thousands in the course of her work.

While the research will not yield immediate clinical benefits, it has the potential to identify new targets for drugs to treat osteoarthritis, and to decrease the length of time it takes for drugs to be tested and brought to the clinic. Watch this space!

Omega-3 fish oil – new research shows it can prevent or slow progression of osteoarthritis

New research has shown for the first time that omega-3 in fish oil could “substantially and significantly” reduce the signs and symptoms of osteoarthritis.

According to the study published in the journal Osteoarthritis and Cartilage, omega-3-rich diets fed to guinea pigs, which naturally develop osteoarthritis, reduced disease by 50 per cent compared to a standard diet.

The research is a major step forward in showing that omega-3 fatty acids - either sourced from fish oil or flax oil – may help to slow down the progression of osteoarthritis, or even prevent it occurring, confirming anecdotal reports and ‘old wives’ tales’ about the benefits of fish oil for joint health.

“This current research…is exciting.”

The charity’s medical research director Professor Alan Silman said: “The possibility that omega-3 fatty acids could prevent osteoarthritis from developing has been a tantalising one. Some limited, previous research in dogs has suggested that we were a long way away from understanding the potential use in humans. However, this current research in guinea pigs is exciting as it brings us closer to understanding how omega-3 might fundamentally interfere with the osteoarthritis process, and that it could potentially be taken as a treatment.”

Lead researcher Dr John Tarlton, from the Matrix Biology Research group at Bristol University’s Veterinary School, said classic early signs of the condition, such as the degradation of collagen in cartilage and the loss of molecules that give it shock-absorbing properties, were both reduced with omega-3.

“Furthermore, there was strong evidence that omega-3 influences the biochemistry of the disease, and therefore not only helps prevent disease, but also slows its progression, potentially controlling established osteoarthritis,” he said.

Dr Tarlton added: “The only way of being certain that the effects of omega-3 are as applicable to humans as demonstrated in guinea pigs is to apply omega-3 to humans.

“All of the evidence supports the use of omega-3 in human disease.”

However, osteoarthritis in guinea pigs is perhaps the most appropriate model for spontaneous, naturally occurring osteoarthritis, and all of the evidence supports the use of omega-3 in human disease.”

On the back of the results of his study, Dr Tarlton said that following government guidelines on dietary intake of omega-3 fatty acids could be effective in reducing the burden of osteoarthritis. Fish oil is far more effective than the flax oil based supplement, but for vegetarians flax oil remains a viable alternative.

“Most diets in the developed world are lacking in omega-3, with modern diets having up to 30 times too much omega-6 and too little omega-3. Taking omega-3 will help redress this imbalance and may positively contribute to a range of other health problems such as heart disease and colitis.”

Further studies were needed to determine the influence of omega-3 fatty acids on established disease in guinea pigs, and to confirm the effects in human osteoarthritis, said Dr Tarlton.

Editor’s note: The total intake of omega-3 recommended by the government is 2 g a day. Most of this amount is found in an individual’s normal diet. Someone with a good diet, for example, might not need to take extra supplements as the actual amount of supplementation depends on the quality of their diet. Normal supplementation capsules are either 450 mg or 1,000 mg of fish oil.

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