TB vaccine could help asthmaFebruary 27, 2002THE protection the BCG vaccine provides against tuberculosis is notoriously poor. But it could hold the key to a vaccine against asthma, which now affects one in seven children in the West. Klaus Joseph Erb`s team at the University of Würzburg in Germany gave mice nasal sprays containing the bacterium used in the BCG vaccine. When they later exposed the mice to the egg-white protein ovalbumin, which usually gives them asthma-like symptoms, their lungs remained healthy. The tests provide further support for the hygiene hypothesis, which blames over-cleanliness for the inexorable rise in asthma and other autoimmune diseases in the West. According to this theory, exposure to common soil bacteria shifts the immune system`s reaction to allergens from the Th2 response that causes the symptoms of allergies to the less harmful Th1 response. (New Scientist, 18 July 1998, p 26).
These soil bacteria are closely related to the TB bug, and observations in Africa have suggested that TB and its relatives can also have a protective effect. So Erb`s team reasoned that BCG, a mild strain of the bacterium that causes TB in cows, might also protect against asthma when sprayed into the lungs. "The biggest surprise was that the mycobacteria didn`t have to be alive to cause the effect," says Erb. Only injections of live BCG can protect people against TB. Crucially, his team also showed that the balance had shifted away from the Th2 response. So-called T helper 2 (Th2) white blood cells had vanished from the mice`s lungs. Also banished were eosinophils, cells that aggravate asthma by releasing histamine. In their place, Erb found high levels of interferon-gamma, a messenger substance that he thinks excludes the Th2 cells. "It could be the signal saying: `Don`t come in`, or `Don`t stay`," he says. But both the live and killed versions of BCG caused lung inflammation in the mice, which would be unacceptable in people. "The last thing you should put into the lung of an asthmatic is something that causes even more inflammation," Erb says. "The trick is to find which components of the vaccines do the trick so you still get the benefits without any side effects." So he and his colleagues are testing fragments of the dead bacteria to see if any of them protect against asthma without causing inflammation. Most promising, he believes, are "CpG motifs"-slugs of bacterial DNA unusually rich in the nucleotide bases guanine and cytosine that provoke a strong immune response. Other groups are also developing asthma vaccines. SR Pharma of London is already carrying out trials with a heat-killed soil bacterium, Mycobacterium vaccae, which is injected into the skin. Initial results suggest it does reduce the severity of asthma and eczema in patients. But a vaccine that can be safely delivered to the lungs might be even more effective. Graham Rook of University College London, a cofounder of SR Pharma, adds that the focus of research is shifting away from simply trying to alter the Th2/Th1 balance. His and other groups are studying regulatory T cells that can completely block both responses. Author: Andy Coghlan More at: Vaccine (vol 20, p 1532) http://www.newscientist.com New Scientist issue 2nd March 2002 PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS STORY AND, IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO : http://www.newscientist.com New Scientist Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Titanium Asteroids Green Tea Acetaminophen Jupiter Sleeping Sickness Water Molecules Mortality Rate Water Weight Management Inflammatory Bowel Disease Seizures Emotions Graphene Bone Density Child Abuse Climate Change Sleep Contraception Cell Membrane Neutron Star Thyroid Cancer Volcanic Eruption Broadband Galaxy Cluster
See More: Science News Tags | |||||||||||||||||||||
|
Related Asthma Current Events and Asthma News Articles ATS, ERS jointly issue asthma assessment guidelines The American Thoracic Society and the European Respiratory Society have released official standards for clinical trials and practice with respect to the assessment of asthma. Study Characterizes Eczema Patients Most at Risk for Dangerous Viral Infections Eczema patients at risk for serious viral infections have more severe disease, are more likely to be allergic to food and other allergens, and have a frequent history of staph infections. Salt block unexpectedly stretches in Sandia experiments To stretch a supply of salt generally means using it sparingly. Pitt Researchers Zero In on Ozone With Fluorescent Solution That Detects Harmful Molecule in the Air and Body Researchers at the University of Pittsburgh have developed a fluorescent substance that glows bright green when exposed to even minute amounts of ozone in the air and in biological samples such as human lung cells. Children susceptible to pesticides longer than expected, study finds Although it is known that infants are more susceptible than adults to the toxic effects of pesticides, this increased vulnerability may extend much longer into childhood than expected. Adults with asthma not getting their flu shots Because of increased risk of complications from influenza, vaccination of adults and children with asthma is recommended by the Advisory Committee on Immunization Practices. Group Health Cooperative shows investing in more primary care pays for itself An evaluation of recent innovations in delivering primary care at a Group Health Cooperative medical center shows significant success and rapid return on investment. Breakthrough in understanding severe asthma has potential for new treatment Scientists from King's College London and Imperial College London believe they have discovered a key element in the development of chronic asthma. Top notch decisions in the developing airways bring insights into lung disease In the normal lung, the airways are lined by a balanced mixture of ciliated, secretory and neuroendocrine cells which perform functions as diverse as air humidification, detoxification, and clearance of environmental particles. Middle-aged women experience more stress but have lower blood pressure Both blood pressure and serum lipid levels have improved in Swedish middle-aged women during the past 30 years. More Asthma Current Events and Asthma News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||