Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

HIV-1 kills immune cells in the gut that may never bounce back

06.12.2006
People with HIV have been living longer, healthier lives since the development of highly active antiretroviral therapy (or HAART) in 1995.

In fact, most patients on the drug regimen do so well that, according to blood tests, their immune cells appear to return to pre-HIV levels. But two new studies from Rockefeller University and the Aaron Diamond AIDS Research Center (ADARC) show that the immune cells in other body tissues may never rebound, suggesting the need for additional ways to monitor immune system health, and the need for hypervigilance as HIV-positive patients live into their forties, fifties, sixties and beyond. The findings are reported in today's issue of PLoS Medicine and online in the Journal of Virology.

Prior research had shown that, just two to four weeks after contracting HIV-1, the lymphoid tissue layer in the mucous membrane of a patient's gastrointestinal (GI) tract can lose up to 60 percent of its CD4 memory T cells -- immune cells responsible for recognizing invaders and priming other cells for attack. Intrigued, Martin Markowitz, an Aaron Diamond Professor at Rockefeller University and a staff scientist at ADARC, wanted to know whether this loss was reversible, and whether giving patients HAART during the early infection period helped restore these cells to the GI lining the way it restored them to the blood itself.

In a paper published today in PLoS Medicine, Markowitz, Rockefeller researcher and clinical scholar Saurabh Mehandru, and their colleagues report on a trial of 40 HIV-1 positive patients who began treatment with HAART shortly after contracting the virus -- during the acute early infection phase -- and who they followed from one to seven years. The researchers found that although the blood population of CD4 T cells rebounded to normal levels, a subset of the GI tract population remained depleted in 70 percent of their subjects.

... more about:
»CD4 »HIV »HIV-1 »Markowitz »T cells »tract

"If we sample the blood, it only has two percent of the total volume of these cells. It doesn't give us the whole picture," Markowitz says. "But if we actually go into tissue, we see something different. What we see there is eye-opening." After three years of intensive drug therapy that suppresses HIV replication very effectively, most patients still had only half the normal number of CD4+ effector memory T cells in their GI tracts.

"Obviously the first question is, why" What's the mechanism"" Markowitz says.

A second paper, published online in the Journal of Virology, makes some headway toward an answer. By examining the viral burden of DNA and RNA in cells from the GI tract, and comparing that to cells from the peripheral blood, Markowitz, Mehandru and their collaborators determined that the mucosal lining of the GI tract carried a disproportionately heavy viral load. That means that the initial loss of CD4 T cells in that area is partially due to virus activity. But the researchers also found evidence suggesting that there are at least two more ways in which the cells were being killed off. Some of the T cells self-destruct (a process called activation-induced cell death or apoptosis), while some appear to be killed by other cytotoxic immune cells.

"These papers speak strongly to HIV pathogenesis, to HIV therapy, and to understanding how the host and virus interact," Markowitz says. However, the short and long term consequences of the persistence of this depletion remain unknown.

In the clinic, if the loss of CD4 T cells in the GI tract translates into increased incidence of colonic polyps or colorectal cancer, routine monitoring practices will have to be re-examined, with HIV-positive patients receiving colonoscopies earlier and perhaps more frequently than current recommendations allow. In the laboratory, these findings should give researchers another angle with which to approach HIV vaccines.

"What good is a vaccine going to be if you get immune responses in peripheral blood but there's nothing in tissue"" Markowitz says. "It's pretty clear that a successful vaccine will need to address issues surrounding mucosal immunity, which is an area that -- relatively speaking -- has been previously ignored."

Kristine Kelly | EurekAlert!
Further information:
http://www.rockefeller.edu

Further reports about: CD4 HIV HIV-1 Markowitz T cells tract

More articles from Life Sciences:

nachricht Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University

nachricht Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>