Role of the microbiota in asthma
A selection of talks on Immunology & Inflammation
Lymphocyte homing: getting lymphocytes to the right place at the right time
- Prof. Ann Ager
- Cardiff University, UK
Hi, I'm Brett Finlay. The talk today is about the Role of the Microbiota in Asthma. And I'm situated in the University of British Columbia, in Vancouver, BC.
So there's a lot of discussion about why diseases, characteristic of Western nations, are increasing. And one of the concepts that's being kicked around is something called the hygiene hypothesis, and this suggests that, perhaps, we're actually living too cleanly in our childhood now and we're not exposed to many microbes we normally would have been exposed to early in life. And there's lack of exposure early in life might mean that later in life, we actually react to these things in various autoimmune type responses. So we know that infectious disease rates have absolutely plummeted in developed countries over the last 50 years. This is due to the advent of vaccines, antibiotics, and also our quest to clean up our world. We sterilize water, we ensure food is safe, and we really have done everything in our control to get rid of microbes, and as a result, we have succeeded in really decreasing infectious disease rates. However, in those same 50 years, we've seen a massive spike in what we call Western lifestyle diseases. These are obesity, type-1 diabetes, asthma, et cetera. And this has corresponded precisely with the decreased infectious diseases. And this has led to the current concept that, well, maybe in our quest to get rid of these infections, we've actually cleaned up our world too much, and as a result, we're actually... Microbes might have something to do with playing a role in how these diseases may actually develop.
So Martin Blaser has championed a term he calls the "disappearing microbe" hypothesis, that is, that we are killing off all our microbes that are normally beneficial, and each generation, we have less and less microbes. So, you know, the average child gets 10-12 courses of antibiotics before they get to school, and we also know that antibiotics have a drastic effect on the microbes in and on us. So on the graph shown on this is just really a characterization of the microbiota in three different mice, an untreated mouse, a streptomycin-treated mouse, and a metronidazole-treated mouse. Streptomycin and Metronidazole are two antibiotics that obviously kill different microbes. But the take home message here is that by using these antibiotics, we're affecting many, many microbes and entire microbial composition that is the microbiota found in these animals. So the idea is that as we clean our world up, we use all these antibiotics and we try and get rid off all these microbes that maybe we actually can't even go back to have the microbes that our great, great grandfathers and grandparents actually had. So maybe, this is causing these microbes to disappear, and maybe this is also compounding these Western lifestyle type diseases.