 |
|
Researchers use chemical from medicinal plants to fight HIV
November 10, 2008TAT2, used in Chinese herbal therapy, prolongs killer T-cells' ability to divide
Like other kinds of cells, immune cells lose the ability to divide as they age because a part of their chromosomes known as a telomere becomes progressively shorter with cell division. As a result, the cell changes in many ways, and its disease fighting ability is compromised.
But a new UCLA AIDS Institute study has found that a chemical from the Astragalus root, frequently used in Chinese herbal therapy, can prevent or slow this progressive telomere shortening, which could make it a key weapon in the fight against HIV.
"This has the potential to be either added to or possibly even replace the HAART (highly active antiretroviral therapy), which is not tolerated well by some patients and is also costly," said study co-author Rita Effros, a professor of pathology and laboratory medicine at the David Geffen School of Medicine at UCLA and member of the UCLA AIDS Institute.
The study, to be published in the Nov. 15 print edition of the Journal of Immunology, is available online at http://www.jimmunol.org/cgi/content/full/181/10/7400
A telomere is a region at the end of every cell chromosome that contains repeated DNA sequences but no genes; telomeres act to protect the ends of the chromosomes and prevent them from fusing together - rather like the plastic tips that keep shoelaces from unraveling. Each time a cell divides, the telomeres get shorter, eventually causing the cell to reach a stage called replicative senescence, when it can no longer divide. This seems to indicate that the cell has reached an end stage, but, in fact, the cell has changed into one with new genetic and functional characteristics.
A great deal of cell division must take place within the immune system for the system to function properly. For example, the so-called "killer" CD8 T-cells that help fight infection have unique receptors for particular antigens. When a virus enters the body, the killer T-cells whose receptors recognize that virus create, through division, versions of themselves that fight the invader.
Generally, the telomeres in cells are sufficiently long that they can divide many times without a problem. Moreover, when fighting infections, T-cells can turn on an enzyme called telomerase, which can prevent the telomeres from shortening.
"The problem is that when we're dealing with a virus that can't be totally eliminated from the body, such as HIV, the T-cells fighting that virus can't keep their telomerase turned on forever," Effros said. "They turn off, and telomeres get shorter and they enter this stage of replicative senescence."
Previous studies have shown that injecting the telomerase gene into T-cells can keep the telomeres from shortening, enabling them to maintain their HIV-fighting function for much longer. This gene-therapy approach, however, is not a practical way to treat the millions of people living with HIV.
For the present study, rather than utilizing gene therapy, the researchers used a chemical called TAT2, which was originally identified from plants used in traditional Chinese therapy and which enhances telomerase activity in other cell types.
They tested TAT2 in several ways. First, they exposed the CD8 T-cells from HIV-infected persons to TAT2 to see if the chemical not only slowed the shortening of the telomeres but improved the cells' production of soluble factors called chemokines and cytokines, which had been previously shown to inhibit HIV replication. It did.
They then took blood samples from HIV-infected individuals and separated out the CD8 T-cells and the CD4 T-cells - those infected with HIV. They treated the CD8 T-cells with TAT2 and combined them with the CD4 T-cells in the dish-and found that the treated CD8 cells inhibited production of HIV by the CD4 cells.
"The ability to enhance telomerase activity and antiviral functions of CD8 T-lymphocytes suggests that this strategy could be useful in treating HIV disease, as well as immunodeficiency and increased susceptibility to other viral infections associated with chronic diseases or aging," the researchers write.
University of California - Los Angeles
"This has the potential to be either added to or possibly even replace the HAART (highly active antiretroviral therapy), which is not tolerated well by some patients and is also costly," said study co-author Rita Effros, a professor of pathology and laboratory medicine at the David Geffen School of Medicine at UCLA and member of the UCLA AIDS Institute.
The study, to be published in the Nov. 15 print edition of the Journal of Immunology, is available online at http://www.jimmunol.org/cgi/content/full/181/10/7400
A telomere is a region at the end of every cell chromosome that contains repeated DNA sequences but no genes; telomeres act to protect the ends of the chromosomes and prevent them from fusing together - rather like the plastic tips that keep shoelaces from unraveling. Each time a cell divides, the telomeres get shorter, eventually causing the cell to reach a stage called replicative senescence, when it can no longer divide. This seems to indicate that the cell has reached an end stage, but, in fact, the cell has changed into one with new genetic and functional characteristics.
A great deal of cell division must take place within the immune system for the system to function properly. For example, the so-called "killer" CD8 T-cells that help fight infection have unique receptors for particular antigens. When a virus enters the body, the killer T-cells whose receptors recognize that virus create, through division, versions of themselves that fight the invader.
Generally, the telomeres in cells are sufficiently long that they can divide many times without a problem. Moreover, when fighting infections, T-cells can turn on an enzyme called telomerase, which can prevent the telomeres from shortening.
"The problem is that when we're dealing with a virus that can't be totally eliminated from the body, such as HIV, the T-cells fighting that virus can't keep their telomerase turned on forever," Effros said. "They turn off, and telomeres get shorter and they enter this stage of replicative senescence."
Previous studies have shown that injecting the telomerase gene into T-cells can keep the telomeres from shortening, enabling them to maintain their HIV-fighting function for much longer. This gene-therapy approach, however, is not a practical way to treat the millions of people living with HIV.
For the present study, rather than utilizing gene therapy, the researchers used a chemical called TAT2, which was originally identified from plants used in traditional Chinese therapy and which enhances telomerase activity in other cell types.
They tested TAT2 in several ways. First, they exposed the CD8 T-cells from HIV-infected persons to TAT2 to see if the chemical not only slowed the shortening of the telomeres but improved the cells' production of soluble factors called chemokines and cytokines, which had been previously shown to inhibit HIV replication. It did.
They then took blood samples from HIV-infected individuals and separated out the CD8 T-cells and the CD4 T-cells - those infected with HIV. They treated the CD8 T-cells with TAT2 and combined them with the CD4 T-cells in the dish-and found that the treated CD8 cells inhibited production of HIV by the CD4 cells.
"The ability to enhance telomerase activity and antiviral functions of CD8 T-lymphocytes suggests that this strategy could be useful in treating HIV disease, as well as immunodeficiency and increased susceptibility to other viral infections associated with chronic diseases or aging," the researchers write.
University of California - Los Angeles
HIV Current Events and HIV News RSSMany pregnant women avoid HIV screening in Africa
'Prevention is the best cure' is a common expression, but what happens if preventative measures are not used? A large proportion of pregnant Ugandan women are going out of their way not to be HIV tested, increasing the risk of mother-to-child transmission.
An atomic-level look at an HIV accomplice
Since the discovery in 2007 that a component of human semen called SEVI boosts infectivity of the virus that causes AIDS, researchers have been trying to learn more about SEVI and how it works, in hopes of thwarting its infection-promoting activity.
New findings suggest strategy to help generate HIV-neutralizing antibodies
New discoveries about anti-HIV antibodies may bring researchers a step closer to creating an effective HIV vaccine, according to a new paper co-authored by scientists at the Vaccine Research Center of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.
Research calls for better assessment of tests for tuberculosis, HIV/AIDS and malaria
A rapid and accurate diagnosis is the first step towards treatment in the fight against infectious disease.
No-entry zones for AIDS virus
The AIDS virus inserts its genetic material into the genome of the infected cell. Scientists of the German Cancer Research Center have now shown for the first time that the virus almost entirely spares particular sites in the human genetic material in this process. This finding may be useful for developing new, specific AIDS drugs.
Hoping for a fluorescent basket case
Although recent advances have raised hopes that a protective vaccine can be developed, acquired immunodeficiency syndrome (AIDS) remains a major public health problem.
Scientists explain binding action of 2 key HIV antibodies; could lead to new vaccine design
A very close and detailed study of how the most robust antibodies work to block the HIV virus as it seeks entry into healthy cells has revealed a new direction for researchers hoping to design an effective vaccine.
U.S. and European Experts Applaud Creation of New Transatlantic Task Force on Global Antibiotic Resistance Threat
Experts on both sides of the Atlantic applaud President Barack Obama and Swedish Prime Minister Fredrik Reinfeldt, representing the European Union (EU) Presidency, for establishing a transatlantic task force to address antibiotic resistance, an urgent and growing problem that threatens patient safety and public health worldwide.
1930s drug slows tumor growth
Drugs sometimes have beneficial side effects. A glaucoma treatment causes luscious eyelashes. A blood pressure drug also aids those with a rare genetic disease.
Indiana U. at APHA: Studies about why men and women use lubricants during sex
An Indiana University study involving 2,453 women ages 18 to 68 found that lubricant use during sexual activity alone or with a partner contributed to higher ratings of pleasurable and satisfying sex.
More HIV Current Events and HIV News Articles
 |
100 Questions and Answers About HIV and AIDS by Joel Gallant (Author) |
 |
The First Year: HIV: An Essential Guide for the Newly Diagnosed (First Year, The) by Brett Grodeck (Author), M.D. Daniel S. Berger (Foreword) This supportive resource explores the next generation of HIV/AIDS drugs and also includes new research on HIV and crystal meth, as well as new insights for the hardest hit population — African Americans. |
 |
Living with HIV: A Patient's Guide by Mark Cichocki (Author) This helpful guide offers a wealth of information for individuals who have been diagnosed with HIV and for people caring for HIV positive friends and loved ones. It covers the entire HIV lifespan, from prevention to diagnosis and beyond. Valuable tips help the reader make the best decision when choosing a doctor, finding and adhering to the right medication regimen, and, if necessary, making end-of-life plans. All aspects of HIV/AIDS are discussed, including opportunistic and associated infections, dental care, exercise and nutrition, substance use and abuse, and emotional treatment. |
 |
HIV Essentials 2010 by Paul E. Sax (Author), Calvin J. Cohen (Author), Daniel R. Kuritzkes (Author) HIV Essentials 2010 incorporates the latest clinical guidelines into a step-by-step guide to the diagnosis, evaluation, management and prevention of HIV infection and its complications. Topics include: HIV diagnosis, evaluation, treatment and prevention; Opportunistic infections and other HIV Complications; Treatment of HIV and pregnancy; Antiretroviral drug summaries; Post-exposure Prophylaxis; New section to each drug summary called "How Supplied" describes the commercially available dosage forms for all the ARV's |
 |
Home Access HIV - 1 Express Test System - 1 ea by Home Access Next Day Results* Contains one single-use sample collection kit |
 |
The Naked Truth: Young, Beautiful, and (HIV) Positive by Marvelyn Brown (Author), Courtney Martin (Author) The surprisingly hopeful story of how a straight, nonpromiscuous, everyday girl contracted HIV and how she manages to stay upbeat, inspired, and more positive about life than ever before At nineteen years of age, Marvelyn Brown was lying in a stark white hospital bed at Tennessee Christian Medical Center, feeling hopeless. A former top track and basketball athlete, she was in the best shape of her life, but she was battling a sudden illness in the intensive care unit. Doctors had no idea what was going on. It never occurred to Brown that she might be HIV positive. Having unprotected sex with her Prince Charming had set into swift motion a set of circumstances that not only landed her in the fight of her life, but also alienated her from her community. Rather than give... |
 |
HIV and the Pathogenesis of AIDS, 3rd Edition by Jay A. Levy (Author) The new edition of HIV and the Pathogenesis of AIDS provides a state-of-the-art review of the current research, explains the history of the disease, and examines how scientists, clinicians, and public health workers have responded to the challenges presented by HIV/AIDS in the 25 years since its recognition. Many exciting developments in the field have deepened scientific understanding of HIV/AIDS and have provided novel approaches for prevention and treatment. The book explores potential approaches for therapy and a vaccine for the prevention of HIV infection and AIDS is discussed. Thoroughly updated and revised, the third edition continues to provide a comprehensive analysis of the subject that is unmatched in the field. Figures and tables illustrate and emphasize key points and... |
 |
Absolutely Positive Directed By: Peter Adair Also With: Janet Cole (Cinematographer), Peter Adair (Cinematographer), Peter Adair (Writer) Ten years following its ground-breaking debut at Sundance, the landmark film that first humanized the face of AIDS is now available in this special 10th Anniversary Edition. Simultaneously heart-wrenching and life affirming, ABSOLUTELY POSITIVE is an hon |
 |
HIV/AIDS: A Very Short Introduction (Very Short Introductions) by Alan Whiteside (Author) HIV/AIDS is without doubt the worst epidemic to hit humankind since the Black Death. As of 2004 an estimated 40 million people were living with the disease, and about 20 million had died. Despite rapid scientific advances there is still no cure and the drugs are expensive and toxic. In the developing world, especially in parts of Africa, life expectancy has plummeted to below 35 years, causing a serious decline in economic growth, a sharp increase in orphans, and the imminent collapse of health care systems. The news is not all bleak though. There have been unprecedented breakthroughs in understanding diseases and developing drugs. Because the disease is so closely linked to sexual activity and drug use, the need to understand and change behavior has caused us to reassess what it means... |
 |
Home Access HIV - 1 Test System - 1 ea by Home Access Please note: Due to packaging updates, the image shown may temporarily appear different |
| © 2009 BrightSurf.com |