Microbial Gut Bacteria and our Immune System Part 6

Here is the write up from Part 6 of the meeting with Les.

–Diet
–Gut Bacteria
– immune system
– the hygiene hypothesis(if you haven’t heard of this yet, you will be fascinated)

Les:
… There isn’t a direct comparison, for example that if you eat this food, its going to have a direct affect on how our immune system acts. But we know very clearly that our diet affects the microbes in our gut. And there’s also very clear evidence now that the microbes in our gut affect our immune system. So even though we can’t provide the direct links to say: this food will cause this bacteria to grow and will have this specific affect, there’s enough examples of this type of thing going on that we have to say “Diet can affect the gut microbes and that can affect the immune system”. And that’s a message that many physicians simply are unaware of.

Adam: Is that idea or that fact relatively new? Or is that something that has been studies for years and years and years?

Les:
The first sorta hints of this do go back decades, but just in the last few years there’s been a real resurgence in this topic and part of it is we have had advances in our scientific technology. We are able to study these bacterial communities more easily. Also, advances that allow us to study the body’s immune system more easily. So we scientists sometimes can be pretty stubborn to let go of old ideas. That can be a good thing, you don’t want to be seduced by every fad that comes along. But, often times if you can’t show a scientist a mechanism as to why something happens, it tends to be taken a little less seriously. It has only been in the last few years that there have been studies that are starting to demonstrate at a mechanistic level(by mechanistic level I mean we know which gene in a bacterium encodes a certain protein, and we know what that protein does. It may be an enzyme that makes a certain small molecule that’s present on the surface of a bacterium, and we know that this one molecule by itself can interact with the immune system of the host and cause a definite effect. We know the genes that are involved, the microbe, the proteins, the molecules, we know what molecule on the surface of our immune system is the one that latches onto this chemical messenger, and we can track the series of messages that happen in the human immune system that ultimately lead to a certain reaction.
We know at the molecular level every step in the chain. And now we’ve got a clear mechanism. And what we know, a few specific examples of this specific things, its almost certainly just the tip of the iceberg. There’s going to be a HUGE amount, many many more interactions that we don’t know about yet. But it means that all of a sudden, a scientist who’s up on this literature should not be dismissing the potential to say that we control or we can influence the activity of our immune system by what we eat. Because there is clear potential for it to happen, and there’s obviously clear stories which suggest that it is happening. We are at the stage to say there is something going on here, we don’t know what it is, but there’s something.

Adam: How about this, with regards to what you do here, is there a lot of studies that you know about throughout the world that are related to IBD, colitis and diet? Is there a lot of stuff going on in the world, is it a priority?

Les:
So I’m not a physician, I’m not an expert on inflammatory bowel diseases. Scientists, the way we tend to work is we tend to carve out a niche. So I’m less aware of whats happening in research on IBD because its not the specific thing I research. I’m somewhat aware because other studies on the gut microbe I pay attention to it. It’s certainly getting some attention. The fact that Crohn’s Disease and Ulcerative Colitis have increased dramatically in the last decades, its seen a part of the increase in a whole host of immune regulated type disorders, because there’s been MS, Lupus, Rhuematoid arthritis, ashma, allergies, all of these are seen as developed world diseases. Ashma is almost unheard of in hunter gatherer societies, or subsistence based agricultural societies. It’s a disease of more developed cultures. The same for Crohn’s and Ulcerative Colitis. And so people have noticed this phenomenon. There’s been a huge increase in certain parts of the world, and they are trying to figure out why. Some interaction with the human microbiota is seen as a hypothesis, that the reason potentially. Why children that grow up on farms are less likely to have allergies like asthma, or kids that are less exposed to antibiotics, again less likely to have exzema or psoriasis or allergies. Maybe because the normal interactions that happen with our microbiota and our human body are things that actually turn down some of the inflammatory responses. We start living in a hyper clean enviornment, I’m not even talking about the “finatics” who are trying to sterilize their homes , but simply just living in the city away from farms and farm animals may be enough and then beyond that maybe you get these people that are nuts about getting traclosan and antibacterial products everywhere in the home. They may be setting themselves up and their kids up for some of these diseases of a mis-regulated immune system. Because our immune system normally regulates itself while in communication with these microbes, its part of our gut and other places in our body. It’s got a name, it’s called the Hygiene Hypothesis, that in affect taking away our normal microbial interactions has led to an increase in all these spectrum of immune dis-regulation diseases.

I hope you all enjoyed learning about gut bacteria, we’ve all go it,

Adam Scheuer