Laboratory
Study Helps Explain Why People with HIV Are More Susceptible to Tuberculosis
 | A
laboratory study reported in the July 2009 issue of the Journal of Leukocyte
Biology sheds new light on how HIV-related changes in cytokine levels and
immune cells in the lungs render HIV positive individuals more susceptible to
tuberculosis, a combination with high mortality in resource-limited countries. |
Below
is a press release from the journal describing the findings. Harvard
scientists solve mystery about why HIV patients are more susceptible to TB infection
New
research published in the Journal of Leukocyte Biology describe how HIV switches
off the immune response to mycobacterium tuberculosis
A team of Harvard scientists
has taken an important first step toward the development of new treatments to
help people with HIV battle Mycobacterium tuberculosis (TB) infection. In their
report, appearing in the July 2009 print issue of the Journal of Leukocyte
Biology (http://www.jleukbio.org)
they describe how HIV interferes with the cellular and molecular mechanisms used
by the lungs to fight TB infection. This information is crucial for researchers
developing treatments to help people with HIV prevent or recover from TB infection.
"HIV/TB
co-infection is a critical global health problem, especially in developing countries,"
said Naimish Patel, MD, lead researcher on the study and Instructor of Medicine
at Beth Israel Deaconess Medical Center and Harvard Medical School. "We hope
that these findings will lead to further studies and possible new therapies for
treating or preventing tuberculosis in HIV disease."
Patel and colleagues
made their discovery by extracting immune cells called "alveolar macrophages"
from the lungs of otherwise healthy, asymptomatic HIV-positive patients as well
as from people who did not have HIV. In people who are HIV-positive, the macrophages
have a decreased response to the TB bacterium when compared to people who did
not have HIV. To learn why, the scientists examined lung specimens from the HIV-positive
patients and found increased levels of a molecule called IL-10, which elevated
the amount of a protein called "BCL-3" in alveolar macrophages and that
reduced their ability to ward off TB infection.
"HIV and TB represent
two of the most significant health challenges in human history and the combination
of the two infections is particularly devastating because HIV dramatically increases
the severity of TB infection," said John Wherry, PhD, Deputy Editor of the
Journal of Leukocyte Biology, "There are still many unknowns about how HIV
reduces the ability of the body to combat other infections. This study sheds light
on co-infection with HIV and TB, which up to this point, has perplexed scientists
and physicians alike."
7/10/09 Reference
NR
Patel, K Swan, X Li, and others. Impaired M. tuberculosis-mediated apoptosis in
alveolar macrophages from HIV+ persons: potential role of IL-10 and BCL-3. Journal
of Leukocyte Biology 86 (1): 53-60.
July 2009. (Abstract).
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