(8 Total References)
Genetically Modified Organisms
Ricki Helm, PhD
...Ricki HelmDr. Helm received his PhD from the Department of Immunology, University of Manitoba, Winnipeg, Manitoba, and held postdoctoral positions in the Department of Biochemistry, Oklahoma State University, Stillwater, Oklahoma, and the Department of Anatomy and Cell Biology, University of Miami, Miami, Florida.
Subsequently, as a Research Associate in the Department of Immunology, Mayo Clinic, Rochester, MN, research interests involved allergen characterization and standardization with responsibilities to the NIAID/NIH/WHO
Subcommittee on Allergen Standardization.Dr. Helm
then accepted an Assistant Professorship in the Division of Allergy/Immunology, Department of Pediatrics, University of Arkansas for Medical Sciences
, Little Rock, Arkansas to continue studies on inhalant and food allergens, specifically addressing mechanisms of IgE-mediated.A recent transfer to the Department of Microbiology/Immunology and the Arkansas Children's Nutrition Center
has led to investigations into pediatric gastrointestinal immune development and maturation.His
research/academic career includes eighty-one peer-reviewed journal publications, sixteen book chapters and two patents involving peanut allergens.
Soy allergies affect fewer than 1 percent of American children, though the allergies are more prevalent in Asian countries, where soy is a staple, said Dr. Ricki M. Helm, an allergy specialist at the Arkansas Children's Hospital in Little Rock.
Nonallergenic crops could be used for special products, like soy formula for babies allergic to soy.If enough nonallergenic crops are grown, the overall level of allergens in the food supply may fall enough to limit the risks of accidental exposure.
"The ultimate goal is to make foods more safe so ingestion of hidden allergens will not cause anaphylactic or dangerous food reactions," said Dr. Helm
, who is working on the less allergenic soybean with scientists from the Department of Agriculture
and from Pioneer Hi-Bred and its parent company, DuPont
Allergies occur when the body reacts to particular proteins.Genetic engineering can be used to remove, or knock out, the genes responsible for producing the allergenic proteins.One way to do this is by putting in a backward copy of the gene in question, so it cancels out the plant's own gene.Or, just putting in an extra normal copy of the gene sometimes prompts the plant to shut down both the implanted gene and its own.
To create the less allergenic soybean, the scientists removed a protein, P34, that accounts for about 65 percent of the soybeans' allergenicity.
But P34 is only one of three major allergens in soy, so eliminating it means the soy will be "marginally more safe but not completely safe," Dr. Helm
said.The next step will be to eliminate the other two allergens.
One big question is whether removal of the genes will hinder the plant's ability to grow or change the characteristics of the soy.If it does, "you have a hypoallergenic seed but have no use for it," Dr. Helm
But so far, they have not been able to get the plants to produce the altered proteins, said Dr. Helm
, who is involved in the project.
Scientists at the University of California at Berkeley
have tried to make a less allergenic wheat by inserting a gene to increase production of an enzyme that breaks down certain sulfur bonds that are present in many allergens.With the bonds broken, the proteins would be more easily destroyed by stomach acids before they can provoke allergic reactions.
Personal Submission before the Committee on
Ricki M. Helm, an immunologist at Arkansas Children's Hospital Research Institute, said that swine have many advantages as an animal model for allergens.Like humans, swine develop the allergic symptoms, such as rhinitis, runny noses, and diarrhea, to food and environmental allergens.With skin tests, pigs show positive responses to allergen extracts.Also, their anatomy, physiology, and nutritional requirements are very similar to humans, and their immune systems mature in much the same way as human immune systems.
IN SWINE TESTS that Helm
conducted for peanut allergy, piglets were sensitized to peanuts by giving them large doses soon after birth.Later they were exposed to high levels of peanuts, and many exhibited allergic symptoms, such as rashes and puffiness around the eyes.No animal was allowed to go into anaphylactic shock.The research on peanut allergies in swine may help in understanding and preventing peanut allergies in children, he
said.It also shows that swine may be useful for testing the allergenic potential of transgenic food.
Speakers at the meeting disagreed about whether political leaders and the public would ever condone studies conducted on people to see whether they respond to potential food allergens.
Science-based Approaches to Assessing Allergenicity of New Proteins in Genetically Engineered Foods
Since the publication of the Astwood et al. paper in 1996, there have been a number of scientific meetings, symposia and papers that have further discussed protocols (or the need for them) for testing digestive stability; these are reviewed by Dr. Ricki Helm, of the Arkansas Children's Hospital Reseach Institute, in his paper "Stability of Known Allergens (Digestive and Heat Stability)" written for the FAO/WHO expert consultation.
The paper by Dr. Helm (Helm, 2001) served as a starting point for discussion of the Joint FAO/WHO Expert Consultation on Allergenicity of Foods Derived from Biotechnology.
The final report of the Expert Consultation recommended a slightly modified version of Dr. Helm's
protocol (for example, rather than test the protein at a range of pHs to simulate the stomach at various times after feeding, the FAO/WHO Expert Consultation recommends testing only at pH 2.0), but it contained far more specific details about what the protocol should contain.
One significant extension of Dr. Helm's
protocol that the FAO/WHO Expert Consultation
included was the notion that "the expressed protein should be assessed in its principle edible form under identical pepsin degradation conditions to those used to examine the expressed protein" (FAO/WHO, 2001: 12).
Furthermore, as Dr. Helm
pointed out in his
paper for the FAO/WHO Expert Consultation
, recent industry and scientific thinking in this area concur: "The working committee on the 'Characteristics of Protein Food Allergens' held by ISLI/HESI following the symposium established the following criteria be taken into consideration. . . . 3-Deliver: Consideration should be given to how the material will be introduced into the diet.
Assessment of allergenicity should be based on the matrix/matrices that the novel protein would be introduced into the diet" (Helm, 2001: 6).
Finally, if a significant portion of the expressed protein does survive digestion in SGF, we recommend that it be tested further in SIF, using the protocol laid out by Dr. Helm
Both allergy scientists as well as the Environmental Protection Agency
(EPA) consider stability of a protein to heat to be a characteristic property of food allergens (Sampson, 1999; EPA
, 2001; Helm
, 2001; and Taylor and Hefle
In contrast to the EPA's lack of a consistent protocol, Dr. Helm
has developed a science-based protocol as part of the paper on the topic that he
wrote for the 2001 FAO/WHO Expert Consultation
: "Heat Stability: The definition of heat stability should be standardized using the following criteria.
1-Heat treatment of the novel protein, native and recombinant, should be for 5 minutes at 90°C.
2-Assessment of stability by a combination of molecular sieving using HPLC and standardized SDS-PAGE analysis (both native and denaturing/reducing gels).
See SDS-PAGE protocol below" [see the section on digestive stability, above for this protocol] (Helm, 2001: 8-9).
We urge that the FDA
require data on heat stability and use the science-based protocol as outline by Dr. Helm
Helm, R.M. 2001.
Topic 5: Stability of Known Allergens (Digestive and Heat Stability).
Working Paper Biotech 01/07 for the Joint FAO/WHO Expert Consultation
on Allergenicity of Foods Derived from Biotechnology, January 22-25, 2001.
Genetically Modified Organisms
Ricki M. Helm, PhDUniversity of Arkansas for Medical SciencesArkansas Childrens Hospital Research Institute