Green Tea Component Could Help Fight HIV Infection
A chemical that occurs naturally in green tea appears to prevent HIV-1 (the virus associated with AIDS) from infecting cells in the immune system and could prove a valuable part of treatment for the disease, said researchers from Baylor College of Medicine and Texas Children’s Hospital in a report that appears in the current issue of the Journal of Allergy and Clinical Immunology.
In previous studies, Dr. Christina Nance, assistant professor of pediatrics at BCM, and Dr. William T. Shearer, professor of pediatrics at BCM, had demonstrated that epigallocatechin gallate or EGCG, found in green tea, blocks the ability of HIV-1 to attach to a cellular entry molecule called gp120. This inhibits the virus’ ability to infect cells.
Paramount from global aspect
"Now we have shown that EGCG can inhibit infection not only in a specific strain of HIV-1 but in multiple subtypes and strains," Nance said. "This is paramount from a global aspect. Most initial studies with HIV-1 in the Americas are based on subtype B." However, most of the world is infected with other strains.
"Previously, we had shown how it worked," she said. "This is definitive proof that the compound inhibits actual HIV infection in lymphocytes or T-cells.
In fact, she said, they are planning a study of the compound in people in the near future.
In this study, they exposed immune cells from the blood of people who did not have HIV/AIDS to the virus in the laboratory. They then incubated these HIV-infected immune cells with EGCG. They found that the compound blocked the ability of the virus to infect other cells. Molecular components of the compound called pryogallol and galloyl appear to be responsible for the prevention of the gp120 protein from attaching to the CD4 molecule found on T-cells, a key component of the immune systems.
This effect occurs at concentrations that would be non-toxic to people, said Nance.
"Thus, EGCG may represent a potential low-cost inhibitor of global HIV-1 infection that could be used at least as adjunctive anti-HIV therapy," said Nance and Shearer in their report.
Next phase of testing
Previous drugs developed to block the entry of HIV-1 into cells proved ineffective because the virus mutated.
"Once HIV is exposed to drug, it finds a way around it," said Nance. She said she hopes that EGCG, derived from a natural product, will be less likely to generate such mutations. Currently, she is doing tests to determine whether EGCG will generate such resistant mutations.
That preliminary work could help clear the way for early patient studies, she said. BCM has received a grant from the National Institutes of Health to being a phase 1 trial to study the safety of the compound in HIV-1-infected people.
Dr. Edward B. Siwak, assistant professor of molecular virology and microbiology at BCM, also took part in this research.
Funding for this work came from the National Institutes of Health and the Baylor Center for AIDS Research.
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