Today we are lucky enough to have the opportunity to publish a post written by Mike Daniels – one of the researchers behind the recent discovery that a drug used for the treatment of period pain may have a role to play in the treatment of Alzheimer’s disease. We hope you enjoy the opportunity to slip behind the lab bench and see what happens behind the scenes of a big scientific discovery.
My name is Mike Daniels, I am a PhD student working at the University of Manchester. We’ve just published a paper in the journal Nature Communications on how currently available drugs may be used to treat Alzheimer’s disease. The Brain Bank North West got in touch with us and gave us a fantastic opportunity to add our voice to the current media storm surrounding this research. I hope I can give you a detailed look at the ins and outs of this important research and offer some insight into the workings of a big research project.
Our lab group are particularly interested in AD, not just because it affects over 26 million people worldwide without any truly effective treatment but also because our speciality is immunology and research suggests that an overactive immune system may play an important role in AD. One particular part of that immune system recently implicated in AD is something called an inflammasome. The inflammasome is a large bundle of proteins which forms a kind of machine within cells whose job it is to produce proinflammatory cytokines. These cytokines go on to promote inflammation in the brain which can worsen AD.
What’s particularly exciting for us is that this inflammasome appears to be largely redundant in everyday immune functions like fighting bacteria or viruses. This means we should be able to inhibit it in patients without rendering them susceptible to infection.
OK so we have a plan – inhibit the inflammasome complex in the hope of improving outcomes for people living with AD. But how do we do this? We could design new drugs (something our lab is involved in right now) but the process of getting a new drug from bench to clinic can take around 20 years and cost around 1.6 billion dollars. Another quicker, cheaper option is to do something called ‘repurposing’, this basically means taking a drug already approved and on the market and using it to treat a different disease. With this in mind our lab head Dr. David Brough decided to test a number of drugs from a large class called non-steroidal anti-inflammatory drugs (NSAIDs) to see if they could inhibit the inflammasome and thus potentially be used in AD. So, this was the project I was tasked with in my first week of PhD life nearly two years ago.
We began by testing a number of these NSAIDs on immune cells cultured in a petri dish. This gave us the important opportunity to screen a large number of drugs without unnecessary use of animals. When we ran these screens we had a bit of a surprise. The more famous NSAIDs such as ibuprofen (Nurofen) had no effect. However, one drug, mefenamic acid, was able to inhibit the inflammasome and prevent release of inflammatory cytokines in the cells. Mefenamic acid is only available by prescription and is prescribed largely to treat period pain.
So, how does mefenamic acid inhibit the inflammasome?
Research suggests that ion channels on the cell surface play an important role in inflammasome activation and that mefenamic acid may inhibit some types of ion channels. To better understand this we formed a collaboration with a London-based research group led by Dr. Claudia Eder – an expert in electrophysiology (researching ion channels). It was with the help of Dr. Eder’s lab that we identified the target of the drugs as a chloride channel called the volume-regulated anion channel (VRAC).
Now we had the drug and the mechanism but we still don’t know whether this drug would be effective in treating AD. This is where we needed to look at the drugs action in a living system. The first model system we chose was a rat model of amyloid-beta induced memory deficits. Build-up of amyloid-beta is a thought to be a major factor in memory impairment and AD. Indeed, if injected into the brain of rats, amyloid-beta causes permanent memory deficits. As part of a collaboration with Dr. Mike Harte’s lab here at Manchester, we injected a group of rats with either mefenamic acid or a placebo and found that those which received the drug were completely protected from amyloid induced memory deficits.
We then moved to look at the effect of the drug in a genetic mouse model of AD. These mice had been altered to express some of the same genes found in humans with the genetic form of AD and, like human sufferers, these mice develop memory deficits with advancing age. When treated with mefenamic acid at the age of onset, these mice did not develop memory deficits, unlike animals treated with a placebo. We also found that the brains of placebo mice displayed signs of intense inflammation while those of drug treated mice remained completely normal.
So to conclude, AD is a terrible and currently incurable disease which we believe to be partially caused by an overactive immune system – specifically over-activity of a protein complex called an inflammasome. We found that the commercially available drug mefenamic acid was able to inhibit the inflammasome and reduce memory loss in both mouse and rat models of Alzheimer’s-like memory deficits.
But what’s the next step? We are hoping to begin to move mefenamic acid into clinical trials to see if it could really work in humans. Luckily, because the drug is already known and approved we can skip the safety testing stage of the clinical trial process. Unfortunately however, clinical trials remain extremely expensive and, as mefenamic is off patent and can no longer be sold for profit, gaining funding through pharmaceutical companies is nigh-on impossible. This means we are relying on grants from fantastic charities such as Alzheimer’s Society and Alzheimer’s Research UK in order to move this study forward.
A lot of work is needed and it will still be a while before we have results in people currently living with AD, but this remains an exciting step and we can only hope that it will go some way to treating this horrible disease.
Guest post by: Mike Daniels
Mike is currently studying for a PhD in neuroinflammation at the the University of Manchester, UK. His work is based mainly on the role of a huge protein complex called the inflammasome in diseases such as Alzheimer’s, stroke and haemorrhagic fever. When he’s not in the lab he’s usually found up a mountain or out in the countryside somewhere and is always on the lookout for any new science outreach ideas!