Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

La Jolla Institute identifies molecular switch enabling immune cells to better fight disease

21.01.2013
Finding on killer cells opens new avenue for combating AIDS, cancer and other diseases

A research team led by the La Jolla Institute for Allergy & Immunology has discovered the mechanism that enables CD4 helper T cells to assume the more aggressive role of killer T cells in mounting an immune attack against viruses, cancerous tumors and other damaged or infected cells.

The finding, made in collaboration with researchers from the RIKEN Institute in Japan, could enable the development of more potent drugs for AIDS, cancer and many other diseases based on using this mechanism to trigger larger armies of killer T cells against infected or damaged cells.

CD4 helper T cells, which normally assist other cells of the immune system during an infection, and CD8 killer T cells, which directly attack and eliminate infected cells, are two of the body's most important immune cells for defending against diseases. Earlier research studies have shown that helper T cells can become killer cells in some instances. However, the specific mechanism of action that allowed this to occur was not known until now.

"We have identified the molecular switch that enables CD4 T cells to override their programming as helper cells and transform into cytolytic (killer) cells," said La Jolla Institute scientist and study co-leader Hilde Cheroutre, Ph.D. "Our team also showed that these transformed helper T cells represent a separate and distinct population of cells. They are not a subset of TH-1 helper cells as previously thought."

Jay A. Berzofsky, M.D., Ph.D., chief of the Vaccine Branch at the National Cancer Institute's Center for Cancer Research, called the finding "a major advance" that provides new understanding about the cell's lineage and basic mechanisms. Dr. Berzofsky was among the researchers whose work in the 1980s first demonstrated that helper cells could convert to killer cells. "Understanding how these cells derive and what causes them to switch from helper T cells to cytolytic T cells is an important step to learning how to manipulate them in disease," he said, noting it could lead to novel approaches "either to turn these cells off in autoimmune disease or turn them on in infectious diseases."

He added that the finding could also have important implications in cancer. "We need all of the cytolytic machinery that we can get to try to destroy cancers," he said. "If we can learn to turn them on, I think it's reasonable to believe that these cytolytic T cells can play an important role in controlling cancer."

The findings were published today in Nature Immunology in a paper entitled "Transcriptional reprogramming of mature CD4 helper T cells generates distinct MHC class II-restricted cytotoxic T lymphocytes." Dr. Cheroutre is co-senior author on the study together with Dr. Ichiro Taniuchi of the RIKEN Research Center for Allergy and Immunology in Yokohama, Kanagawa, Japan. First authors on the paper are: Mohammad Mushtaq Husain, Ph.D., of the La Jolla Institute; Daniel Mucida, Ph.D., formerly of the La Jolla Institute, now at Rockefeller University; Femke van Wijk, Ph.D., formerly of the La Jolla Institute, now at the University Medical Center Utrecht, The Netherlands, and Sawako Muroi, of the RIKEN Institute.

Mitchell Kronenberg, Ph.D., La Jolla Institute president & chief scientific officer, said the study reflects the very successful collaboration between the La Jolla Institute and RIKEN in Japan, which have joined efforts on a number of projects over the years.

In the study, the researchers found that a certain transcription factor, which are molecules in the cell nucleus that control the activity of cells, continually suppresses the killer T cell lineage in helper T cells. Using mice, the team showed that turning off this transcription factor (ThPOK) enabled the helper cells in the body's peripheral areas, like the blood, spleen and the intestine, to override their original programming and to become killer T cells. "While our work focused on the intestines, we found that helper T cells in all tissues of the body have the potential to become killer cells in response to recognition of viral, tumor or other antigens in the context of cytokines such as IL-15," said Dr. Cheroutre.

Jonathan Braun, M.D., chair of the Department of Pathology and Laboratory Medicine at UCLA's David Geffen School of Medicine, praised the study as laying the groundwork for using T helper cells in a much more aggressive manner. "Helper T cells are mainly understood for their role in regulating other immune cells," he said. "This work reveals how they themselves can be triggered to become the action cells in the immune response. This opens new possibilities for how to manipulate them therapeutically in disease."

Dr. Cheroutre said the transformation of CD 4 helper T cells into killer cells already occurs in the body naturally. "Our finding could help to explain a number of occurrences that we haven't really understood up to this point, such as why some people can be chronically infected with HIV without developing AIDS." In these instances, Dr. Cheroutre is convinced that CD4 helper T cells must be taking over the role of killer cells after the CD8 T cells become exhausted. "It's like the helper cells can come in as reinforcements to keep the virus under control. If we can develop ways to artificially trigger that process, we may be able to significantly help people with HIV and other chronic infections."

While scientists would want to trigger a larger army of virus-specific killer cells in the case of infections, the opposite would be true in inflammation-fueled autoimmune diseases, like rheumatoid arthritis or multiple sclerosis, said Dr. Cheroutre. "The CD4 T cells are the bad wolves in inflammatory diseases because they often trigger more pro-inflammatory cells which worsen these conditions," she said. "With this knowledge, we may be able to prevent that by coaxing the CD4 killer cells to become regulatory cells instead, which is another one of their potential functions. In regulatory mode, the CD4 T cells suppress the immune system. This suppression reduces inflammatory cells, which is what we want to do in autoimmune diseases."

However in cancer, the CD4 T cell's regulatory function becomes problematic because they inhibit the killer T cells from destroying cancerous cells. This is because of their built-in mechanism to keep T cells from attacking the body's own cells, said Dr. Cheroutre. "Cancer cells develop from our own cells and only look a little different from healthy cells," she explained. "The killer T cells can sense that they are different and decide to eliminate them. However, the CD4 regulatory T cells frequently suppress the killer T cells and prevent them from destroying the cancerous cells. This is often how cancer cells can escape the immune system's normal action of stamping out bad cells."

Dr. Cheroutre said she believes it may be possible, using the newly discovered mechanism, to turn the CD4 regulatory T cells into killer cells that would aid, rather than block, the immune system's attack on cancerous cells.

About La Jolla Institute

Founded in 1988, the La Jolla Institute for Allergy & Immunology is a biomedical research nonprofit focused on improving human health through increased understanding of the immune system. Its scientists carry out research seeking new knowledge leading to the prevention of disease through vaccines and the treatment and cure of infectious diseases, cancer, inflammatory and autoimmune diseases such as rheumatoid arthritis, type 1 (juvenile) diabetes, Crohn's disease and asthma. La Jolla Institute's research staff includes more than 150 Ph.D.s and M.D.s. To learn more about the Institute's work, visit www.liai.org.

Bonnie Ward | EurekAlert!
Further information:
http://www.liai.org

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>