There are two illnesses we suffer from, for which there is no known sure-fire cure- the common cold and asthma. About the common cold, the Dutch say that if you try and treat it, if takes a week to go away and if you leave alone, if goes away in seven days. How we wish this be true of asthma as well!
We now know that the common cold is viral in origin. Fortunately, the immune system of the body fights the virus and clears it in a week. But with asthma it is a different story.
It is a chronic lung disease that inflames and narrows the airways, causing wheezing, shortness of breath and cough. While a variety of treatment modes are attempted, it does not go away and recurs often.
What causes asthma is still a puzzle. But some leads have appeared in recent years that seem to link it to bacteria. Not bacteria that come from the environment to infect us- there is no one “asthma microbe” but a population balance.
What do we mean by this? A recent commentary by Jennifer Couzin-Frankel in the 26 November 2010 issue of Science titled “Bacteria and asthma: untangling the links” summarizes our current knowledge on asthma.
There are some tantalizing clues. The first is this. Children living in farms, urban slums and similar environs are less prone to asthma than those in relatively more hygienic ones. This is somewhat similar to what we notice when our relatives from the US or Europe come visiting. Their children fall sick sooner than our “raised in India” ones. Note too that while “swine flu or HIV was a major epidemic in the West and Japan, we Indians were not affected so badly. (And just look at the rag- picking children in the city. It would be interesting to study how many of them fall sick or suffer from asthma).
This difference goes by what public health people call as the Hygiene Hypothesis. People (and animals) continually exposed to germs build immunity to fight infection while those with a relatively germ- free lifestyle fall sick sooner.
The second is more interesting. Babies born via Caesarian section appear to get asthma more likely than those born by the natural (vaginal) route. The former arrive in the world through a more “sterile” path than the latter.
Ongoing research in Holland suggests that children born by C-section had nearly double the risk than those by natural birth. Likewise was the risk higher in children who had been given antibiotics. The microbial flora in the lungs and guts seem involved in the ‘protection'.
The third clue described by Couzin-Frankel is an experiment done at Michigan. Mice infected in the laboratory with germs in their lungs and intestines appear to get asthma less often than those who were treated likewise but plus an antibiotic drug. Dr Gary Huffnagle, who did this experiment remarks: “The animals are perfectly healthy until we hit them with an antibiotic”.
It is only during the last decade or so that we have come to realize that human body is a veritable zoo-a rich and vast ecosystem where microbes thrive. We are examples of biodiversity in action — not with animals and plants within us, but microbes of all types, sizes and shapes. Without bacteria in our belly, we cannot digest a variety of food. Look how we run to the bathroom after we take antibiotics for infection.
Our body is a township housing microbes that colonize just about every part — stomach, lung, skin ….. And these are bacteria, fungi, viruses- each living off us, propagating and populating. Not all of them are bad; as with the Lactobacilli (which help us digest some types of food), many are called “probiotics”. And over generations, we have learnt and adapted to live and let live. Some of them may well have co-evolved with us.
Biologists call this world of microbes within us as the “microbiome”. While physicists are fond of the suffix “on” -proton, hadron, boson; and chemists “ane, ene, one”- butane, benzene, ketone; biologists are in love with “ome” — genome, proteome and now microbiome.
And as with any vast community of various types of individuals or groups, it is the mutual interaction among and between them that determines health and harmony or “hungama” and “hell break loose”. And the hosts, namely us, have learnt to live with them, control them and keep their numbers optimum (that is what immunity does), and use them just as they use us.
You disturb one colony at one site, the effect may be felt at another part of the body (recall the statement: “a butterfly flexing its wings in the Amazon leading to a tsunami in Sumatra”).
It is the result of this interplay and balance of power that counts — the coalition dharma. Not very different from politicians, is it?
This then might offer a lead to understanding asthma. As Dr. Huffnagle says: “It's really coming down to the bacterial community structure — who's there, and in what numbers, and where”. People with asthma have a different balance of microbes than those that do not. But then, this is no comfort to the asthmatics; what they want is to restore the healthy balance. How this can be done is the challenge to the life scientist.