When the National Institutes of Health launched its project to discover what bacteria grow in different parts of our bodies, it ignored the lungs, because the prevailing view was that healthy lungs were germ-free.
But there is growing evidence that the lungs also have resident colonies of microbes, and two new research projects at the University of Pittsburgh and other U.S. centers are designed to find out whether they play a role in certain lung ailments.
One project, headed at Pitt by Alison Morris and Elodie Ghedin, is looking at the role of the lung microbiome in people living with HIV infections.
The other, led here by Naftali Kaminski, is analyzing how microbes might affect two rare disorders, sarcoidosis and Alpha1-antitrypsin deficiency.
In the early days of the AIDS epidemic, patients often died of pneumonia caused by a fungus called pneumocystis, Dr. Morris said. Even though drugs enable many HIV patients to live with their disease today, their rate of chronic obstructive pulmonary disease is much higher than in people without HIV.
There is some evidence that pneumocystis is still playing a part in that, she said, along with a bacterial species usually found in the intestine, Trophyrema whipplei. The federally funded research will look at whether patients with lung problems have distinctive bacterial colonies.
Sarcoidosis is a disease that can attack the lungs, heart, brain, eyes and skin. It is rare, but afflicts African-Americans three times as often as Caucasians -- 1 in every 2,800 black people vs. 1 in every 9,500 whites.
Alpha1-antitrypsin deficiency is equally rare, affecting one out of every 5,000 to 7,000 people. In people who don't have the disorder, Alpha1-antitrypsin prevents enzymes called proteases from causing too much damage in our bodies, but in people with the disorder, the proteases keep destroying lung and liver tissue.
Doctors can give people with Alpha1 the correct form of the inhibitory substance, but it doesn't always work well.
The concept behind his study, Dr. Kaminski said, is that "you could explain part of the differences in the diseases by differences in the bacterial colonies in the body."
If that turns out to be true, he said, "it should be relatively easy to treat. The thought is you could replenish patients' microbiomes if you know there is something associated with a more accelerated course of disease."
For Dr. Morris, the research is fascinating because "the microbial cells outnumber human cells 10 to 1, and so it's almost like there's this other organ in the human body and it can impact health in ways we don't even know about right now."health