http://www.yale.edu/opa/newsr/06-09-25-05.all.html


Bacterial Protein Shows Promise for Treating Intestinal Parasites

New Haven, Conn.—Scientists at the University of California, San Diego (UCSD) and Yale University have discovered that a natural protein produced by Bacillus thuringiensis, the bacterium sprayed on crops by organic farmers to reduce insect damage, is highly effective at treating hookworm infections in laboratory animals.

Their discovery, detailed in this week’s early online edition of the Proceedings of the National Academy of Sciences, could pave the way for the development of more effective treatments for hookworm and other soil-transmitted nematode infections, which are a major global health problem in developing countries. Many of the nearly two billion people worldwide infected with these intestinal parasites are children, who are at particular risk for anemia, malnutrition, and growth delay.

The UCSD-Yale team found that a protein produced by the bacterium Bacillus thuringiensis, or Bt, whengiven orally to laboratory animals infected with hookworm was as effective as mebendazole in eliminating the parasites, curing anemia, and restoring weight gain in the hamsters. Mebendazole is one of the drugs currently recommended to treat infections in humans. The scientists also discovered that this protein, called Cry5B, targets both developing, or larval, stages and adult parasites, and impairs egg excretion by female worms.

Hookworms cause anemia and weight loss by attaching to the intestine and feeding on their host’s blood and nutrients. The researchers report that this naturally-produced protein has the potential to substantially improve this global health problem because it is safe to humans and other vertebrates and can be produced inexpensively in large quantities.

“Our ability to control parasitic nematode infections with chemotherapy on a global scale is dependent on the availability of medicines that are safe, effective, and inexpensive to manufacture,” said Michael Cappello, one of two principal authors of the study and a professor of pediatrics and epidemiology & public health at Yale School of Medicine. “We believe that Bt crystal proteins not only meet, but exceed these essential criteria.”

This discovery is particularly relevant in light of concerns about the potential resistance in human intestinal nematodes to currently available medications. “There are few new agents under development for the treatment of hookworm and other intestinal parasite infections,” said Raffi Aroian, an associate professor at UCSD and co-principal author of the study. “Crystal toxins are safe to humans, mammals and other vertebrates. And it might be possible to improve the efficacy of current treatments by giving mebendazole and Cry5B simultaneously.”

Other authors of the study are Richard Bungiro and Lisa Harrison at Yale School of Medicine and Larry Bischof, Joel Griffitts and Brad Barrows at UCSD.

Aroian and his UCSD colleagues discovered five years ago that the roundworm C. elegans and other nematodes are susceptible to the effects of Cry5B, then known primarily as an insecticide. The toxin forms tiny holes in the membranes of the cells of nematodes and insects. However, since the toxin cannot bind to the cells of mammals or other vertebrates, they do not hurt humans.

“Crystal proteins had been used for decades by organic farmers who sprayed their crops with Bt to kill insects,” said Aroian. “Until now, however, no one has used a purified Cry protein to treat a parasitic nematode.”

At a meeting of the Burroughs-Wellcome Fund, Aroian met Cappello, a Pediatric Infectious Diseases specialist who studies hookworm. They decided to collaborate on a project to see if crystal proteins could be effective against hookworm infections. Three years ago, Aroian and his colleagues purified Cry5B toxin and sent it to Cappello at Yale Medical School, who then tested the compound in a laboratory model of hookworm infection.

“It worked on the first day,” said Aroian. “Laboratory animals treated with Cry5B survived a lethal hookworm infection, and showed no side effects from the medication.”

Colleagues in Cappello’s lab then demonstrated that Cry5B was comparable to mebendazole for treating hookworm infection in laboratory animals. Additional studies also determined stages in the life cycle of the parasite that were most susceptible to Cry5B and what concentrations that were most effective.

“These experiments confirmed that the mechanism of action of Cry5B in Ancylostoma hookworms appears to be identical to that for other nematodes, including C. elegans,” said Cappello. “This suggests that crystal proteins will likely have activity against a broad range of parasitic worms, and could be used to treat children who are often infected with multiple intestinal parasites. Studies are underway to fully define the spectrum of activity of Cry5B as part of its preclinical development as a human therapeutic.”


Same article, but with before an after images from UCSD.


http://www-biology.ucsd.edu/news/article_092506.html



"A purified Bacillus thuringiensis crystal protein with therapeutic activity against the hookworm parasite Ancylostoma ceylanicum":


http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=170...


Yale University School of Medicine
New Haven, CT 06520, USA.

Crystal (Cry) proteins produced by the soil bacterium Bacillus thuringiensis (Bt) are harmless to vertebrates, but they are highly toxic to insects and nematodes. Their value in controlling insects that destroy crops and transmit human diseases is well established. Although it has recently been demonstrated that a few individual Bt Cry proteins, such as Cry5B, are toxic to a wide range of free-living nematodes, the potential activity of purified Cry proteins against parasitic nematodes remains largely unknown. We report here studies aimed at characterizing in vitro and in vivo anthelminthic activities of purified recombinant Cry5B against the hookworm parasite Ancylostoma ceylanicum, a bloodfeeding gastrointestinal nematode for which humans are permissive hosts. By using in vitro larval development assays, Cry5B was found to be highly toxic to early stage hookworm larvae. Exposure of adult A. ceylanicum to Cry5B was also associated with significant toxicity, including a substantial reduction in egg excretion by adult female worms. To demonstrate therapeutic efficacy in vivo, hamsters infected with A. ceylanicum were treated with three daily oral doses of purified Cry5B, the benzimidazole anthelminthic mebendazole, or buffer. Compared with control (buffer-treated) animals, infected hamsters that received Cry5B showed statistically significant improvements in growth and blood hemoglobin levels as well as reduced worm burdens that were comparable to the mebendazole-treated animals. These data demonstrate that Cry5B is highly active in vitro and in vivo against a globally significant nematode parasite and that Cry5B warrants further clinical development for human and veterinary use.


Three short articles seemingly related in the big picture of things (imo):

Advances
Health and Science news from Yale


http://www.medicineatyale.org/v3i1_jan_feb_2007/advances.html#top_of_page


In bacteria vs. worm, children are winners

If the bacterium Bacillus thuringiensis (Bt) did battle against the parasitic hookworm Ancylostoma ceylanicum, who would prevail? According to new research, the biggest victors may be the nearly 1 billion people infected by hookworms worldwide—especially children, who risk anemia, malnutrition and growth delay.

Bt-produced substances known as crystal proteins are commonly used on crops to control insects and worms. Michael Cappello, M.D., professor of pediatrics, microbial pathogenesis and public health, and colleagues at the University of California, San Diego, found that a Bt crystal protein known as Cry5B might also be an effective treatment for parasitic worm infections.

In the October 10 issue of the Proceedings of the National Academy of Sciences, Cappello and colleagues report that Cry5B inhibits hookworm growth in laboratory dishes and in infected hamsters. In the hamsters, Cry5B was as potent as a conventional anti-parasite medication in reversing weight loss and anemia, and no toxic effects were evident.

Ruling the fate of a cellular blank slate

Stem cells make identical copies of themselves and can differentiate into many of the myriad cell types that form the body’s tissues and organs. To maximize these cells’ therapeutic versatility, they must be maintained in an undifferentiated state.

Some researchers have suggested that oxygen levels are low within the stem cell niche—the microenvironment within tissues that determines whether stem cells regenerate or differentiate. Seeking a method to preserve stem cells in their blank slate form, Zhong Yun, Ph.D., assistant professor of therapeutic radiology, and colleagues took a cue from nature, mimicking those low-oxygen conditions for cells in the lab.
As reported in the October 13 issue of The Journal of Biological Chemistry, under these conditions stem cell-like fat precursor cells remained in an undifferentiated state. And when the team upped the oxygen level, the precursor cells could again be converted into fat cells.

“Once we know how the microenvironment regulates the functions of stem and progenitor cells,” says Yun, “we can potentially protect them from premature differentiation or find ways to mobilize these cells for tissue repair and regeneration.”

How the stressed become depressed

Some individuals persevere in hardship; others crumple like paper dolls. Mental fortitude in the face of stress has been linked to variations in a gene that regulates the neurotransmitter serotonin: individuals with a short version of the gene have a greater propensity to fall into Depression under stress, while those with the longer version are more resilient.

To gain a glimpse of how these genetic differences might interact with stress to produce depression, R. Todd Constable, Ph.D., professor of diagnostic radiology and biomedical engineering, and colleagues in New York and Germany used brain imaging while individuals carrying short or long forms of the gene looked at images of faces.

Other work had suggested that short-gene carriers who had experienced life stress would show an elevated response to sad or fearful faces in brain areas involved in Depression and coping.

But in the October 24 issue of Proceedings of the National Academy of Sciences, Constable and colleagues reported less activation in short-gene carriers under these conditions and greater activation at rest. This pattern may reflect “a chronic state of vigilance, threat, or rumination” in short-gene carriers that makes them more vulnerable to Depression under stress.

The immune system in a sticky situation

Neutrophils, critical cells of the early immune response, travel quickly through the bloodstream to sites of infection to engulf and kill bacteria. If genetic defects slow down this neutrophil migration, more severe infections may result.

School of Medicine researchers have now identified a key gene that regulates neutrophil movement through the body, which may clarify why some individuals are more susceptible to infection and inflammation.
A team led by Richard A. Flavell, Ph.D., Sterling Professor and chair of Immunobiology and Howard Hughes investigator, reports in the October 6 issue of Science that mice lacking the gene Myo1f have neutrophils that adhere more readily to their surroundings and are therefore markedly slower in reaching sites of infection.
Myo1f, not previously known to play a role in immunity, limits the number of proteins known as integrins on the cell surface. In the gene’s absence, more integrins are released, making neutrophils more sluggish. “Without Myo1f, immune cells get too sticky and cannot move fast,” says first author Sang-won V. Kim, Ph.D., now at Memorial Sloan-Kettering Cancer Center. “So the host becomes vulnerable to acute infection.”