Astragalus extract studied to strengthen immune response to HIV

We’re always fascinated when modern laboratory science identifies mechanisms that help to explain how traditional botanicals work. Here’s an example regarding Astragalus, among the traditional botanicals of Chinese medicine. On this blog you can find several reports of earlier research pointing to this herb’s application to immune support. But according to UCLA investigators who have just published their findings in the Journal of Immunology, an extract of Astragalus also performs a very specific function at the cellular level in support of immune function–and thus may hold special promise for enhancing the effectiveness of HIV treatments.

Here’s a description of the new Astragalus research posted on http://www.aidsmeds.com on Nov. 10, 2008:

When cells reproduce, their DNA gets capped at the ends by long repeated strands of genes called telomeres. Telomeres protect the genes, much like the plastic tips on the ends of shoelaces. Unfortunately, telomeres get shorter every time a cell reproduces, which ultimately causes the cells to become “exhausted” and to stop functioning properly. This occurs naturally as a person ages, but more rapidly in the HIV-fighting CD4 and CD8 cells of people with HIV.

One of the lead researchers in telomeres and HIV, Rita Effros, PhD, and her colleague Steven Russell Fauce, PhD, of the department of pathology at UCLA, had experimented with gene therapy as a way to keep telomeres from shortening. But ultimately the researchers turned to what could potentially be a much less expensive method: an extract from the medicinal plant astragalus.

According to Effros and Fauce, the extract, TAT2, keeps an enzyme called telomerase turned on. CD4s and CD8s can naturally produce telomerase, which helps keep telomeres from shortening, but only for so long. After a cell has divided too many times, the telomerase gene turns off.

In test tube experiments, Effros and Fauce exposed CD4 and CD8 cells collected from HIV-positive patients to TAT2. Not only did the substance slow the shortening of the cells’ telomeres, but it also increased the cells’ production of proteins known to inhibit HIV replication.

While studies of TAT2 have not yet been conducted in people, the authors believe the 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.”

Reference: http://www.aidsmeds.com/articles/hiv_astragalus_telomere_1667_15595.shtml

The story is being widely reported this week, so you’ll find other accounts as well. We also note that Astragalus has been one of the botanicals stocked by HIV/AIDS buyers’ clubs for years, based both on its use for immune support in Traditional Chinese Medicine, and on a recent wave of scientific interest. (Of course we’d like to have more information on the relationship between the extract employed in the UCLA study and the components of the botanical as it is traditionally harvested and crafted for medicinal use.)

For more information, see other entries under “Astragalus” on this blog, or the NYBC entry:

Astragalus

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