FeaturesOct/Nov 2008 Issue

Research Roundup: Alzheimer’s Disease

Alzheimer’s Disease

Tomato, Tom-ah-to
Researchers in Korea have created an oral vaccine against Alzheimer’s disease using tomatoes.

Alzheimer’s disease is believed to be caused by an accumulation of plaque in the brain, namely beta-amyloid, a toxic protein substance that kills nerve cells, leading to dementia. One strategy scientists are examining is a vaccine that would trigger the human immune system to stop or slow the production of beta-amyloid, thereby protecting the brain and nervous system from Alzheimer’s.

Since beta-amyloid is toxic to animal cells, the researchers turned their attention to creating a plant-based vaccine. Tomatoes were chosen because they can be eaten raw (heat can destroy proteins that trigger an immune response). The scientists created the vaccine by inserting the beta-amyloid gene into the tomato. They then fed it to the mice once a week for three weeks. Several weeks later, the mice received a booster. Blood analysis revealed that the mice had a strong immune response after the booster.

Although the vaccine didn’t reduce the amount of plaque already present in the mice, the work, which is in very early stages, shows that transgenic tomatoes may lay the foundation for future Alzheimer’s immunization. Currently the researchers, whose findings are published in Biotechnology Letters, are working to increase the potency of the vaccine.   

Treating Egg Allergy
One in 17 children under the age of three has a food allergy, with egg among the most common allergens, according to the American Academy of Allergy, Asthma and Immunology. Egg allergy is one that many children outgrow by the time they are 6 years old; avoiding egg is currently the only treatment.

Now an early study conducted by researchers in Greece and published in the Journal of Allergy and Clinical Immunology suggests that exposure to heat-treated egg, such as in baked goods like cake, may enable children with egg allergy to tolerate it.

In the study, about 100 egg-allergic children received cake containing an increasing amount of egg protein over a period of several months. About 90 percent were able to ingest ever-higher amounts of egg protein over time without negative results. Six months later, those who had been receiving the cake underwent a challenge test to whole egg. Less than 5 percent had a reaction.

Researchers are now running a controlled study and recommend additional larger trials to more fully evaluate their work. In the meantime, they caution that allergic reactions can occur even to heat-treated egg.

Parents of allergic children should not introduce egg in any form without consulting their doctor.

Over-Medicating Asthma
Researchers from Johns Hopkins University recently published the results of a survey on asthma treatment that they conducted with some 500 pediatricians. The survey was part of a project to develop an asthma assessment tool for doctors in order to learn more about what information pediatricians use to make decisions about treatment.

National guidelines recommend that doctors assess symptom frequency to decide whether to step up or step down treatment, with the goal to control asthma with the least amount of medication. But the survey found that doctors use additional information — such as the patient’s hospitalization history, whether symptoms bother parents and whether symptoms worsen or improve — to guide their decision-making. Each doctor evaluates and weighs these factors differently.

Although reducing asthma medications when indicated is an important goal, the authors write, “pediatricians in our study appeared far less willing to step down therapy, even when these same dimensions of asthma health indicated controlled asthma.”
Several studies suggest that many patients with well-controlled asthma can have their asthma therapy safely reduced.

Stepping down treatment can lower the risk of adverse side effects and better define disease severity and responsiveness to treatment, the authors say. “Pediatricians should be sensitive to minimizing exposures to therapies that are not needed, particularly given parental concerns about side-effects from inhaled steroid therapies.”

“Asthma medications can have serious, albeit infrequent, side effects and while under-treatment is undeniably a big problem, not stepping down treatment when a child is doing well may be, too,” says lead investigator Sande Okelo, M.D., an asthma specialist at Hopkins Children’s Center, in a press release.

Effective tools and strategies for pediatric asthma management should underscore the importance of stepping down therapy, according to the child’s overall asthma status, the authors add. And since the disease can change so much, asthmatic children should have follow-up exams every three to six month, even when they don’t have symptoms.

Fish Oil during Pregnancy
Research published in the American Journal of Clinical Nutrition suggests that fish oil may play a role in reducing the risk of asthma. The work was begun in 1990 when more than 500 pregnant women in Denmark, who were participating in a study, were randomly assigned to one of three groups: one that took olive oil capsules during their third trimester; one, fish oil capsules; and one that took no oil supplement.

Sixteen years later, researchers looked at records from a national health registry that tracks hospital visits and found that the kids born to moms who’d taken the fish oil supplements were estimated to have a 63 percent lower risk of developing asthma and other atopic diseases and an 87 percent lower risk of developing allergic asthma than the children from the olive oil group. This follow-up study was funded by the European Union through its Early Nutrition Programming Project.

The researchers don’t know the precise mechanisms at work but they believe that asthma “may be rooted in the intrauterine environment.” Critical aspects of immune system development occur in utero and fish oil may have a positive effect on this development. Fish oil was also associated with longer gestation in this study.

Other maternal and birth-related factors have been linked to a child’s risk of asthma, including maternal smoking, certain infections, antibiotic use during pregnancy, low birth weight, pre-term delivery and cesarean section.

This is not the first study to look at the effects of fish oil on asthma development but, for different reasons, earlier findings haven’t been this conclusive. This study further supports the hypothesis that fish oil taken during the third trimester may reduce asthma risk in children. But “clearly, there is a need for both large [randomized controlled trials] with long follow-ups, as well as mechanistic studies to examine this further,” the authors write. Other research is required to determine the effects of fish oil taken at different times during pregnancy.

Sjurdur Olsen, M.D., who leads the Maternal Nutrition Group at the Statens Serum Institut in Copenhagen and serves as adjunct professor of nutrition at Harvard, emphasizes that “our results need to be confirmed in other randomized trials before changing any dietary recommendations for pregnant women.” LW

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