On the 26th July 2018, Alan Wooler went to see some of the team at UCL who are doing the vital research into finding a cure for Alpha-1. Alistair Jagger who is a PhD student in Prof Lomas’ team was kind enough to show Alan around the labs and answer a few questions on their work.
How they approach finding a cure
“The way we are approaching our research into the mechanisms responsible for AATD deficiency is to attack it from many different angles. Briefly, we have Professor David Sattelle and Dr Freddie Partridge along with PhD student Anwen Brown who are experts in genetics and they are using the model system C.elegans (a microscopic nematode worm) to look at alpha-1 antitrypsin deficiency in a whole organism. In addition, our resident cell biologist is Dr Riccardo Ronzoni, and he is looking at alpha-1 antitrypsin deficiency in mammalian cells that are grown in a rich medium in plastic vessels. The benefit of that is obviously you’ve got everything in the cell present, but have more control over a variety of process than one does in a whole living organism such as the nematode worm. The cells are cultured in specialised sterile facilities such as the one shown in the picture on the right. Our final angle of attack is to look at the AAT protein itself outside of any organism or cell. This approach is what we call in vitro and allows us to really understand the protein in its simplest form, characterising the very small atomic level features of polymers and differences between M and Z protein. Our structural biology expert is Dr James Irving, helped by myself and another PhD student, Emma Elliston.”
Do you think alpha-1 is a disease or a condition?
Laughing “yes its kind of difficult to define those two. I think it’s a hard one because AAT deficiency is a bit like a double-edged sword. It’s termed alpha-1 deficiency. The deficiency comes from the fact that this mutation causes the protein to aggregate at the site of synthesis in the liver. These aggregates reduce the amount of AAT in the plasma. In healthy individuals, AAT gets out of liver hepatocytes into the blood plasma and it protects your lungs from degradation.
In addition to the plasma deficiency, the aggregates cause the associated liver cirrhosis. It can manifest completely differently in different individuals. Given that both the liver and lung issues cause disruption to bodily structure and function, I personally believe it is a disease rather than a condition”.
The main role of alpha-1 antitrypsin as a proteinase inhibitor. It protects your lungs from degradation by the protease neutrophil elastase which is a natural process. How it does that is alpha-1 antitrypsin is basically bait or what we call the substrate of the protease. The protease binds to alpha-1 antitrypsin and cleaves it. You get a large conformational rearrangement of alpha-1 antitrypsin where the attached protease is flipped from the top of the molecule to the bottom end. This process is irreversible – meaning that the protease can not then go back and break down the lung tissue. In healthy individuals this process is tightly balanced by alpha-1 antitrypsin that is secreted into the plasma so that your lungs remain unharmed.
We think that the Z mutation (among others) is inducing polymerisation by subtly altering the structure of the alpha-1 antitrypsin protein (brings up a slide on the screen).
This is what we call a negative stain electron microscopy image. We’ve taken a cirrhosed liver.This is an example of what liver tissue looks like when we get it. We slice it up and then mash it up. We isolate the protein and the polymers from that and then we use a very high-resolution technique called Electron Microscopy that is great for looking at large protein species and you can see here the chains of polymers. When the protein accumulates in the liver over time as a result of the Z mutation, these are the structures it forms. Because these polymers cannot be secreted into the plasma your lungs are susceptible to attack and prolonged accumulation of protein in these polymers leads to liver damage.
Does everybody produce the same amount of alpha-1 immaterial of their phenotype?
The amount your body actually produces whether you are M S or Z is actually the same but the amount your body retains in the liver is different. With the smaller amount of S that gets stuck, your liver can probably deal with that and it can clear that over time. Your body has amazing mechanisms for maintaining itself at optimum conditions – called ‘proteostasis’ but because there is so much protein accumulation as a result of the Z mutation, it is possible that it overwhelms the body’s regulatory mechanisms in the liver..
My work in particular involves using a very high powered magnetic (a technique called Nuclear Magnetic Resonance) to determine the minute structural and dynamic changes that go on in the M and Z protein and with the milder S mutation. What we hope this will tell us is the reason why the Z mutation causes the protein to polymerise. Using this information in combination with the wealth of data in the group and other groups we hope to be able to be able to design better treatments for AAT deficiency.
(shows picture) This is me on a big magnet (nuclear magnetic resonance) in Birmingham, just opposite the hospital at the University. We get a spectrum like this (shows picture). Each one of these peaks comes from one an amino acid that’s making up the protein. It is essentially like a weather map. Looking at the correlation between protons on the bottom axis and carbons on the right axis can give you structural information about the protein and hint at information of how the protein folds and how the protein behaves once its folded.
Alan giving Alistair a fundraising certificate as he and his friend Chris Waudby recently (13th July) cycled from the center of London to Paris with no support vehicles all to raise funds and awareness of Alpha-1.
The group photo, from left to right:
Prof Elena Miranda (La Sapienza, Rome)
Dr Riccardo Ronzoni (UCL Respiratory)
Julia Faravelli (Pavia, Italy)
Ibrahim Aldobiyan (UCL)
Mandy Wan (UCL)
Dr Freddie Partridge (UCL Respiratory)
Alistair Jagger (UCL Respiratory)
Prof Anna Fra (Brescia, Italy)
Prof David Sattelle (UCL Respiratory)