Friday, 25 June 2010

Hidden uses of Aspergillus

This recent story written by the prominent restaurateur Raymond Blanc raises the issue of genetically modified food (GM) and its implications for vegetarians, food allergies & intolerances. Raymond Blanc's restaurant Le Manoir is very famous and highly professional in all aspects of preparing food but they feel that they have been caught out by insufficient GM food labelling.
They had a guest who insisted that a particular cheese could not be suitable for a vegetarian, whereas a member of staff at Le Manoir was under the impression that it was. Le Manoir was at fault as animal rennet is used to make many types of cheese and for that guest that constituted an animal food which he could not eat.

Le Manoir now set about sourcing cheese that was suitable for vegetarian use and came across a dilemma. Rennet is now produced by several organisms including Aspergillus niger that have had the gene for rennet introduced into them by genetic manipulation.

Quite apart from the debate of whether or not we should be eating GM food and whether or not those foods are appropriate in a high class restaurant that insists on the finest sourced ingredients, this means that we can now have rennet - in some ways an animal protein - produced by micro-organisms that are certainly not animal in origin.

Should a vegetarian accept these proteins as non-animal? They have never been near an animal but the DNA sequence originates in an animal. Perhaps individuals should be able to make that choice themselves? - but here there is a second point. Food that has been produced using a GM product does not have to be labelled GM, so no-one, restaurateur, customer or consumer knows that they are there and thus cannot make that decision for themselves.

There are now many more examples of  foods or food constituents being made using Aspergillus. There is some evidence that foods can cause allergic reactions, even in parts of the body remote from the digestive system - in fact there are examples of  a food made from a fungus (Quorn) that can cause repiratory problems and include cross reactivity to Aspergillus. This raises the possibility that such foods could adversly effect the allergies of patients suffering from a wide range of allergies, including allergy to Aspergillus e.g. ABPA, sinusitis.

If some foods can contain Aspergillus or other microorganism without our knowledge then perhaps the labeling regulations need to be rethought-out.

Friday, 18 June 2010

Air Conditioning in Cars Can Remove Moulds

We had warned some time ago that the air conditioning units fitted in cars were a potential source of mould spores to the unaware car driver and that the only reliable advice for people who are sensitive to mould spores is not  to use the air conditioning in their cars at all. This warning was based on data in a manufacturers advice note that recommended that air conditioning units in cars should be left on or at least run once per week to prevent the build up of mould contamination in the air filters that form part of the air conditioning system.

There was an accompanying paper that went into some detail on mould contamination from air conditioning units in the house and car which generally supported the advice given above. It also mentioned that antifungals are being applied to some new air con filters which might account for some of their efficiency at removing mould spores from the air, but this seemed to have a useful life of 2 years.

Another research paper has just been published  on this subject and once again it has been shown that the air conditioning filtration material can provide a good environment for moulds to grow in if left with no airflow - so it is recommended not to leave the unit switched off.
However they also showed that once switched on a clean set of filters can be very effective - the number of spores in the air drops 75% within 10 minutes which is a very similar result to the earlier paper.

Guidelines to avoid mould buildup in your car air conditioning
  1. Keep it switched on
  2. Ensure it is maintained regularly
  3. Ensure the filtration material is renewed regularly
  4. If you haven't used your car for a week or more run the air conditioning at full airflow setting for 10 mins before getting into the car

    Friday, 11 June 2010

    Which genes are switched on when an Aspergillus spore is detected by lung cells

    Aspergillus spores are a major part of the process by which the fungus gets into our lungs. They are extremely small and very easily blown into the air and inhaled. If they end up in the lungs of someone who is immunocompromised or allergic they can then cause health problems, sometimes very serious health problems.

    For the rest of us there is no problem. Our lung surfaces are covered with epithelial cells and single celled macrophages and  which actively pursue and engulf spores, completely destroying them and removing them from our bodies. In order to work out what is going wrong when spores manage to stay and infect we need to understand the normal working mechanism.

    Our cells normally keep most of our genes switched off until they are needed. It would be a huge waste of energy & resources to leave everything switched on all the time - rather like someone leaving all the lights on in their home 24 hours a day - think of the electricity bill! This means that when there is a change in the environment of a cell - for example when a spore lands on a lung epithelial cell lining the airways - several genes are switched on and it will be those genes that play an important part of the process of preventing infection.

    The first step is to find out which genes are switched on (or off) when spores land on lung tissue. This is achieved in this paper by introducing jellyfish genes (GFP) into the fungi that produce the spores. This makes them easy to spot using a fluorescent light and a cell sorting machine (FACS) as they glow green.
    The spores were then incubated with lung epithelial cells, sorting out which cells had stuck to a spore using the FACS machine, giving us a sample containing only cells with attached spores.

    Using this incredible technology, it is now possible to find out which genes have been switched on in the cells that bound spores by the use of whole genome microarrays - this technology makes it possible to identify which genes are switched on and by how much.

    The paper identifies 889 genes that are switched on or off, many of which are for cell processes that are expected and already known about (inflammation,  cell repair, cell cycle) but with more work some may be found that are more specific to the process of killing spores and thus teach us something new about the processes involved.

    Carrying out the same process using cells taken from susceptible people could for example show us which genes are not working properly and give us a strong clue as to why those people are more vulnerable to infection.

    Friday, 4 June 2010

    Influenza H1N1 (Swine flu) is a risk factor for Invasive Aspergillosis

    We have found a report of 2 patients suffering from the latest pandemic flu virus (H1N1) in 2009 who went on to develop invasive aspergillosis.
    Both patients were well and had normal immune systems as far as is known, so would not normally have been at risk from invasive aspergillosis.

    However, influenza is known to cause problems with the infected persons' immune system and can cause disruption of the tiny hairs on the surface of our lungs (cilia) that normally push infecting objects like mould spores out of our lungs. These patients can be thus primed for infection, but this isn't thought to be enough to render them at risk from invasive aspergillosis, there has to be a second wave of attack to allow aspergillus to penetrate our immune systems.

    In both cases mentioned in the paper the patient was suffering breathing difficulties and was given steroid therapy to enable stabilization of their breathing. Unfortunately this also renders the patient a little more susceptible to infection as steroids can inhibit the immune system, and this may well have contributed to the outcome.

    Influenza is not therefore the cause of invasive aspergillosis in these cases but if the patient is also receiving steroids then the authors of the paper conclude that the patient should be treated as at risk from invasive aspergillosis.

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