PARADIGM SHIFT: THE ECONOMIST GIVES MICROBES A THUMBS UP!
23 August 2012
In a cover story of its latest edition (August 18, 2012), The Economist talks of a scientific ‘revolution’ in the making due to the drastically changing view of the microbe-human being dynamic.
The story follows research in microbiology over the last couple of decades that has steadily unearthed a wealth of information on how the simple view of human beings as helpless host and microbes as parasitical or pathogenic invaders is being turned ‘inside out’.
By Satya Sivaraman
According to the traditional view (still prevalent in many microbiology textbooks) the human body is a pristine collection of 10 trillion cells, which are themselves the products of 23,000 genes. The emerging idea at the frontiers of science however is that humans are not single organisms, but super-organisms made up of lots of smaller organisms working together. Every human being, carries on and within him/her over 100 trillion bacteria of several hundred species bearing 3 million non-human genes.
Such an understanding was in fact advocated by early pioneers in research on antibiotics like Rene Dubos who compared the human body to soil that contains multitude forms of life and pointed out that ‘infection’ is a normal state of the human being and nothing special on its own. This view had few takers for a long time within both medical research, clinical practice or in public perception, which saw most bacteria as nothing more than a threat to human health.
All that has changed in the last couple of decades thanks to a handful of researchers who maintained there was more to bacteria than just disease. The term "microbiome", now used to describe this ecosystem of bacteria, was coined by the late Joshua Lederberg, who argued that microorganisms inhabiting the human body should be included as part of the human genome, because of their influence on human physiology. One of the leading proponents of this ecosystem approach to bacteria in the human body Stanley Falkow of Stanford University, said in a recent interview to ReAct that he considered bacteria an ‘extension’ of the human body and like any other human organ (www.microbiana.org).
This new understanding of the deeper connections between microbes and components of the human body matters is critical as it points to the fact that both medical researchers and practicing clinicians may have been looking in the wrong place for explanations of various diseases. It also suggests a whole new avenue for treatment. As the leader (editorial) in The Economist puts it ‘if an upset microbiome causes illness, settling it down might effect a cure’.
The Economist article focuses on the medical benefits of this new view of the human-microbe equation and refers to new possibilities of managing the microbiome to solve a long list of ailments such as diabetes, atherosclerosis and heart disease; multiple sclerosis; asthma and eczema; liver disease; numerous diseases of the intestines, including bowel cancer; and autism.
For it turns out that the different species of bacteria that are part of the human body provide people more than 10% of their daily calories by helping break down plant carbohydrates that human enzymes are unable to. Even Mother’s milk contains carbohydrates called glycans, which human enzymes cannot digest, but bacterial ones can.
The microbiome also makes vitamins, such as B2, B12 and folic acid and that too in quantities appropriate to each body’s requirement. The microbiome also helps maintain the human immune system against newer and most hostile species of bacteria entering the body.
The Economist cites the example of some doctors who are now taking the microbiome approach to treating deadly infections such as that caused by Clostridium difficile, which kills 14,000 people a year in America alone. Their experiments have shown it can be eliminated by introducing, as an enema, the faeces of a healthy individual.
The other shift in clinical treatment due to the understanding of the microbiome could come from taking into consideration for gene therapy the millions of genes represented by the bacteria in the human body instead of just the 23,000 human ones.
Yet another promising line of treatment referred by The Economist is the deployment of antibiotics- not to blindly kill all bacteria as currently— but to manipulate so that good bugs spread at the expense of bad ones. Such an approach could also have the major benefit of avoiding resistance to antibiotics, a phenomenon that in thelong run threatens to disrupt much of modern medicine itself.
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