Viral infections in infants can contribute towards asthma development

A team of researchers at the University of Pittsburgh School of Medicine, have found that viral infections in newborns cripple part of the immune system and increase the risk of asthma later in life. They showed infections by the respiratory syncytial virus (RSV), stripped immune cells of their ability to calm down inflammation in the lung’s airways.

The idea that asthma is linked to viral infection is not new. Numerous epidemiological studies have linked the two in humans. But it has not been clear whether the virus itself causes asthma, or whether children who are more susceptible to viruses and subsequently develop wheezing coughs, are also more susceptible to asthma.

The researchers also go on to say that their findings, published in the Journal Nature Medicine, will help develop ways of preventing asthma. The charity Asthma UK said the study had really exciting potential.

One Swedish study showed showed 39% of infants taken to hospital with RSV, had asthma when they were 18. However only 9% of infants who were not ill developed asthma. How the virus might be able to do this was unknown. However now the team of researchers at the University of Pittsburgh School of Medicine, believe they have an explanation. Their experiments on mice showed the virus impaired the ability of a specific part of the immune system, called regulatory T cells, to calm inflammation.

Tina Hartert of Vanderbilt University in Nashville, Tennessee, says, “The paper is an important step towards identifying a biological mechanism and determining a stage during development, that doctors could focus on to prevent asthma. There are already drugs that can target T regulatory cells and block the allergic response. The researchers hope to test what effect these drugs have in primates that have been infected with RSV.”

“But it remains to be seen whether the results in mice will translate to humans. For instance, mice are not normally susceptible to RSV, so they had to be exposed multiple times to develop an infection. By contrast, a human infant who wheezes after a single infection with RSV is more likely to develop asthma.”

“Additionally, lab mice are genetically identical, whereas humans have a great deal of genetic variation that plays a major role in determining who develops asthma. Pollution, environmental factors and insufficient exposure to bacteria also contribute to the disease.”

The researchers said, “There might be a window in early life when the cells are vulnerable to being crippled.” They think the finding could help scientists devise treatments which prevent some people developing asthma. They go on to say, “We feel that both prophylactic and therapeutic approaches can be developed. This is especially desirable in infants who have a strong family history of asthma.”

In conclusion Malayka Rahman, from Asthma UK said, “This research provides vital information on how viruses interact with our immune cells and why this might lead to an increased risk of asthma. What’s really exciting is the potential of these findings to translate into new treatments for asthma in the future.”

Eating nuts whilst pregnant could stop children developing asthma

Eating nuts during pregnancy can reduce the risk of children developing asthma, according to research carried out by researchers from the Harvard School of Public Health, Bostonand the Statens Serum Institute of Copenhagen, Denmark.

In the study published in the Journal of Allergy and Clinical Immunology, researchers examined the relationship between nut intake during pregnancy, and allergic disease outcomes, in early and later childhood of their offspring. The study was published in the peer reviewed Journal of Allergy and Clinical Immunology.

In the past women had been advised to avoid eating peanuts during pregnancy and while breast feeding, if they or the father had a family history of allergic conditions. Parents were also recommended not to give peanuts to children, until they are at least three years old to avoid sensitisation.

But in 2008 the Food Safety Agency (FSA), recommended the advice be dropped, after increasing expert advice and scientific evidence, that avoiding peanuts in early life was making the allergy problem worse. The advice had been in place since 1998 and was partly blamed for the rise of nut hysteria, with parents and children becoming increasingly worried about exposure to peanuts.
Now the Department of Health says, “Women can choose to eat peanuts or food containing peanuts, as part of a healthy balanced diet, unless mothers are allergic to them, or they have been advised not to by their health professional.”

Between 1996 and 2002, Danish women were enrolled in the study during their first antenatal visit. This study included 61,908 women who had a single baby and who had completed all questionnaires.
A 360 item food frequency questionnaire was given at around 25 weeks of pregnancy. This asked about snack consumption in the past month, separately assessing peanut and pistachio intake and the intake of nuts and almonds. Women were questioned about childhood asthma when the child was 18 months and 7 years old.

At 18 months they were asked whether a diagnosis of childhood asthma had been confirmed by a doctor, whether there were wheeze symptoms, and the number of wheeze episodes since birth. At 7 years of age, asthma cases were defined as those who self-reported doctor diagnosed asthma, plus wheezing symptoms in the past 12 months. The presence of other allergies, such as hay fever, was also reported at 7 years of age.

The researchers then looked at the association between nut consumption and the development of asthma, wheezing, or other allergies. The results were that a total of 61% of women (37,323) reported no peanut and tree nut intake during pregnancy, 3% of women (1,639) consumed peanuts one or more times per week, and 9% consumed tree nuts one or more times per week.

The researchers found a general inverse relationship between peanut or tree nut consumption and asthma at 18 months. There was a trend that consumption of peanuts and tree nuts, once monthly and two to three times monthly, significantly reduced risk of asthma compared to no consumption.
In conclusion the researchers stated that, “the results do not suggest that women should decrease peanut and tree nut intake during pregnancy, and that consumption of peanuts and tree nuts during pregnancy, might even decrease the risk of allergic disease development in children.”

This conclusion was backed up by Malayka Rahman, research analysis and communications officer at Asthma UK, who said, “This study suggests that eating peanuts and tree nuts during pregnancy, might decrease the risk of children developing allergic conditions, including asthma.”