March 19, 2013
Genetically Altered Tomatoes Help Promote Good Cholesterol
Lee Rannals for redOrbit.com — Your Universe Online
The authors said this is one of the first examples of a peptide that acts like the main protein in good cholesterol, and it can be delivered simply by eating the fruit. A peptide is a chemical compound containing two or more amino acids coupled by a peptide bond, which is a special link in which a nitrogen atom of one amino acid binds to the carboxyl carbon atom of another.
"There was no need to isolate or purify the peptide – it was fully active after the plant was eaten," said senior author Dr. Alan M. Fogelman, executive chair of the department of medicine and director of the atherosclerosis research unit at the David Geffen School of Medicine at UCLA.
Once the tomatoes were eaten, researchers found the peptide was active in the small intestine, but not in the blood. This suggests targeting the small intestine may be a new strategy to prevent diet-induced atherosclerosis, which is a disease of the arteries that leads to heart attacks and strokes.
The team genetically engineered tomatoes to produce a small peptide that mimics the action of the chief protein in high-density lipoprotein, or apoA-1. Scientists then fed the genetically engineered tomatoes to mice that lacked the ability to remove low-density lipoprotein from their blood. They found mice that ate the peptide-enhanced tomatoes had significantly lower levels of inflammation, higher levels of good cholesterol, and decreased lysophosphatidic acid, which accelerates plaque build-up in the arteries.
After the mice finished eating, the team observed the intact peptide was found in the small intestine, which suggests the peptide acted in the small intestine and was then degraded to natural amino acids before being absorbed into the blood.
"It seems likely that the mechanism of action of the peptide-enhanced tomatoes involves altering lipid metabolism in the intestine, which positively impacts cholesterol," said the study's corresponding author, Srinavasa T. Reddy, a UCLA professor of medicine and of molecular and medical pharmacology.
Previous studies suggested a large number of conditions with an inflammatory component might benefit from treatment with an apoA-1 mimetic peptide, including Alzheimer's disease. With many chronic diseases, inflammation becomes an abnormal, ongoing process with long-lasting harmful effects. Fogelman said if the work in the animal trial is applied to humans, consuming food genetically altered to contain apoA-1 related peptides could improve these conditions.
"This is one of the first examples in translational research using an edible plant as a delivery vehicle for a new approach to cholesterol," said Judith Gasson, a professor of medicine and biological chemistry, director of UCLA's Jonsson Comprehensive Cancer Center and senior associate dean for research at the Geffen School of Medicine. "We will be closely watching this novel research to see if these early studies lead to human trials."
Genetically altering food has been a popular focus for scientists in recent years. In 2011, scientists in China wrote in the Proceedings of the National Academy of Sciences about how they genetically modified grains of rice to help burn victims and patients who suffered severe blood loss. The scientists said their genetically altered rice could help reduce the need for hospitals to obtain plasma through donations.