Could lettuce cure diabetes? U. Central Florida prof working on veggie drug

By Whitney Hamrick

Central Florida Future (U. Central Florida)
08/24/2007

(U-WIRE) OVIEDO, Fla. -- A University of Central Florida professor has developed a therapy, through genetically altered lettuce, that alleviated diabetes in lab mice after 8 weeks of treatment.

The National Institutes of Health provided $2 million for the diabetes study conducted by Professor Henry Daniell of the biological science department.

According to the American Diabetes Association, diabetes is the fifth deadliest disease in the U.S., contributing to 224,092 deaths in 2002. Seven percent of the population, 20.8 million, has diabetes. Every day, 4,110 people are diagnosed with diabetes.

There are two types of diabetes.

"Type 1 diabetics produce no insulin," said Michael Deichen, medical director of UCF Health Services and a specialist in diabetes, in an e-mail. "Typically, a Type 1 diabetic is diagnosed in childhood and has a lifelong need to take insulin shots.

"Type 2 diabetics have less effective insulin. Type 2 diabetics are usually diagnosed in mid-life and have a tendency to be obese.

"Diabetes is an autoimmune disease where autoantigens attack the insulin proteins. If you stop it from the attack, the body will cure itself."

Therein lies the challenge: if you know what it is and know it can be cured, what do you do next?

According to Daniell, previous studies have been conducted involving insulin capsules that failed because the body continues to attack the insulin. This is the same reason why people on insulin therapies must inject themselves daily: because the capsules would do little to relieve the problem.

Taking the theory behind the insulin capsules, Daniell sought inspiration in a previous study he conducted to produce an inexpensive anthrax inoculation through genetically altered tobacco leaves.

Nixing the tobacco leaves due to their stigma with cigarettes, Daniell used lettuce leaves instead.

"We eat lettuce as a fiber so we cannot digest the plant's cell walls," Daniell said to explain his choice in vegetables.

He noted that everyone eats lettuce and has minimal risk of allergy, making it widely susceptible for successful intake as well as easy and inexpensive mass production. That allows the medication cost to go way down.

Daniell said that while pharmaceutical companies are looking for profit, they have done a lot of good in regard to drug therapies.

Diabetics were dying sooner 20 or 30 years ago, but people with the insulin replacement therapy can live longer lives, he said. "The primary motivation for me has been to find a new platform that dramatically reduces the cost of medicine, not only in the U.S. but all over the world. I have worked on developing this new platform for 20 years."

While diabetics in the U.S. struggle to pay for their medication and materials, Daniell said it is the financial burdens of those who make less than $2 a day that are the driving force behind his research.

"My mom has diabetes," said Ali Ahmed, a 17-year-old pre-med biology major who heard about Daniell's study in class. "I think it would be great if it gets approved by the [Food and Drug Administration].

Most of Ahmed's family members on his mother's side have Type 2 diabetes. Five of his uncles in Pakistan have it, and because they are being forced to retire by the Pakistani government, they can't afford the medication.

"Diabetes is mostly prevalent in India and Pakistan with people who typically can't afford the medication," Ahmed said. "If they can make it cheaply and mass produce it, it would be better for them as well as for people in the U.S."

According to studies conducted by the World Health Organization and several European universities, there are currently 31.7 million diabetics in India as of 2004. If the disease keeps up its current trend, by 2030 there will be 79.4 million infected.

With his motivations set, Daniell began testing his theory.

Through a lab machine called a gene gun, the insulin gene is placed into the lettuce's cells. The lettuce is grown in the lab, freeze-dried and then converted to a powder.

The waxy coating of the cell walls protects the insulin so that it can slowly release as bacteria in the intestines breakdown the cells. Then the insulin makes its way into the bloodstream.

To do this, Daniell removed the toxin from the cholera virus and attached the carrier protein receptors the virus uses to enter the bloodstream to the insulin genes in the plant's cells.

Presumed to be a dead organ, this therapy process stimulates the pancreatic islets' remaining stem cells into rehabilitating its insulin-producing beta cells, allowing the organ to heal itself and function normally. Thus, diabetes is alleviated, at least in mice.

There are four phases in human clinical trials that must succeed in order for a new drug to be approved by the FDA.

The first phase assembles 25 to 50 people who start the treatment. The second phase deals with dosage. The third phase looks for potential side effects. In the fourth phase, the drug is read as a product to be approved.

"A cure or significant improvement in the treatment of diabetes would be a very significant landmark for the overall status of American health," Deichen said.

Several hundred people sent e-mails to Daniell, offering to volunteer for the human clinical trials.

http://www.uwire.com/content//topnews082407003.html

Lettuce and Diabetes

by Gretchen Becker
Thursday, August 2, 2007

Can insulin produced in lettuce cure type 1 diabetes some day? Possibly. In mice, it seems to modulate the immune attack on the beta cells that is the hallmark of type 1 diabetes. But the pathway is complex.

Therapeutic insulin is usually injected. This is for two reasons. First, most proteins are partically digested in the stomach. The very acid stomach first denatures the proteins. This means that the very specific folding of a protein that gives it specificity is destroyed, and the protein goes from a compact structure to a long chain of amino acids (the building blocks of proteins).

Then the digestive enzyme pepsin, which works best in an acid environment like the stomach, begins to chop the long chain into smaller bits. Hence, no more insulin.

The second reason is that in a healthy person, the gut easily absorbs small molecules like glucose or individual amino acids. It doesn't usually absorb a lot of proteins in their intact form. So even if insulin were able to make it through the stomach, it wouldn't be absorbed very well.

Inhaled insulin was developed as one way to get around these two problems. There's no acid in the lungs, and they are able to absorb some of the inhaled insulin intact. Insulin sprays in which the insulin is absorbed through the skin of the mouth are another approach.

Now researchers at the University of Central Florida, led by Henry Daniell, are working at an ingenious method to allow insulin -- as well as various vaccines -- to be delivered orally to the gut, where the insulin can act as an immunomodulator, a substance that modulates your immune system response.

First, they're producing the proteins in genetically modified plants. They've used tobacco and, more recently, lettuce to produce human proinsulin (the compound that is broken down in the beta cells into insulin and C-peptide).

Other researchers have produced insulin in other plants, for example, safflower. But by inserting the insulin gene in the plant chloroplasts -- the tiny organs in plant cells that take energy from the sun and use it to make carbohydrates -- Daniell's group has gotten high yields of proinsulin without the danger that the altered genes will spread through pollen. This is because chloroplasts are inherited only through maternal cells, not through pollen (male cells).

Next, by grinding up the plant tissue and feeding the ground up tissue to mice, they've managed to bypass the protein destruction that usually occurs in the stomach. In essence, the plant cells with their cellulose walls are encapsulating the proinsulin and protecting it. Once in the intestine, the plant cells are slowly digested and the proinsulin complex is released.

That leaves the last problem: the fact that intestinal cells don't take up intact proteins very well. To solve this problem, they've complexed the proinsulin with something called cholera toxin B. This is a nontoxic part (the B subunit) of cholera toxin that stimulates intestinal cells to take up proteins.

For the cholera bacterium, it's a trick to get the intestinal cells to take up the intact cholera toxin. For the researchers, it's a trick to get the intestinal cells to take up intact proinsulin.

This system stimulates uptake by cells of the intestinal immune system as well. In NOD (nonobese diabetic -- a standard rodent model of type 1 diabetes) mice, the uptake by the immune cells resulted in a significant increase in compounds that suppress immune responses. The result was a reduction in the immune system attack on the beta cells. It is immunological attack on the beta cells that causes their destruction and is the cause of type 1 diabetes.

In the mice, eventually the beta cells recovered, and their blood glucose levels returned to normal.

Daniell said that after the proinsulin complex is taken up into the interstitial fluid, it does not get transformed into insulin and C-peptide, so there's no danger that eating a lot of the complex would have an effect on blood glucose levels.

The researchers are hoping that this technique, using insulin from modified lettuce plants, can be used to stop beta cell destruction in people who are in the very early stages of type 1 diabetes, when they still have many beta cells left. It might even work in those who have already been diagnosed with type 1 diabetes.

Like much research in mice, however, this treatment is not something that is going to be available tomorrow. Cures in mice don't always translate into human cures. But, like the Toronto work last fall that showed that type 1 diabetes could be cured in mice by manipulating the nerves to the beta cells, this research is a fascinating new approach to the complex problem of diabetes.

"This is a totally new approach. It has great promise," said Daniell. He said that human clinical trials of the lettuce system are in the works.

http://www.healthcentral.com/diabetes/c/5068/11951/lettuce-diabetes/pf/