Researchers identify cell group key to Lyme disease arthritisDecember 04, 2008A research team led by the La Jolla Institute for Allergy & Immunology and Albany Medical College has illuminated the important role of natural killer (NK) T cells in Lyme disease, demonstrating that the once little understood white blood cells are central to clearing the bacterial infection and reducing the intensity and duration of arthritis associated with Lyme disease. "Our findings are that the NK T cells are critical to preventing the chronic inflammatory infection that causes Lyme arthritis and they participate in clearing the bacteria which cause it," said Mitchell Kronenberg, Ph.D., the La Jolla Institute's president & scientific director and co-senior author on the study, which used a mouse model of Lyme disease. Lyme disease is caused by Borrelia burgdorferi, a bacterium transmitted to humans by the bite of infected deer ticks. Typical symptoms include fever, headache, fatigue, and sometimes skin rashes. If left untreated, it can spread to the joints, the heart and the nervous system, and it can lead to serious health problems. Lyme disease currently is the most common vector (insect)-borne disease in the United States. "What this study demonstrates is that NK T cells are an important part of our defense against Lyme disease," said Timothy J. Sellati, Ph.D., an associate professor at Albany Medical College and co-senior author on the study. "This offers the possibility that we can exploit that knowledge therapeutically and potentially develop immunological agents that can trigger more NK T cells to aide in fighting this disease." Sellati added that "NK T cells alone cannot clear Lyme disease, but are a key part of a collective immune defense." The study's findings are outlined in a paper, "NKT cells prevent chronic joint inflammation after infection with Borrelia burgdorferi," published this week in the online version of the journal Proceedings of the National Academy of Sciences. In an earlier study published in Nature Immunology, Kronenberg, Sellati and co-workers had shown that a glycolipid, a type of fat, found in the membrane of Borrelia burgdorferi triggered an immune response from the NK T cells. "We had found that if you gave that lipid to mice or humans, it would activate NK T cells," Kronenberg said. While this suggested the cells might play a significant role in Lyme disease, "we were missing in vivo (in the body) evidence showing that the NK T cells were activated following infection and were important for killing and clearing the Lyme disease bacteria," he said, noting that the latest study demonstrates this in an animal model. Sellati said the finding is particularly important because it opens new lines of investigation as to the causes of chronic Lyme disease. "That's what's so exciting when you identify a new cell type as playing a central role in preventing the disease process," he said. "So in those individuals who have a more severe form of the disease, you can study their NK T cells and see if there's some deficiency that prevents those NK T cells from killing and clearing the bacteria." In their studies, the researchers worked to model the natural route of Lyme disease infection as closely as possible. "The way people typically get Lyme disease is that they're out hiking and they get bitten by a deer tick," said Kronenberg. "So what we did in the lab was to get ticks infected with Borrelia burgdorferi from collaborators at the University of Connecticut Health Science Center and then used those ticks to infect mice in a confined and controlled environment." The researchers used one group of mice genetically engineered not to have NK T cells, while the control group had the cells. "The mice that didn't have NK T cells were not as capable of clearing the (Lyme disease) bacteria," Kronenberg said. "And they developed a chronic arthritis, while the control mice did not." He said the results were quite marked. "You could see under the microscope more numerous inflammatory cells in the joints of the mice that lacked the NK T cells weeks after infection." Discovered in the 1990s, NK T cells are disease-fighting white blood cells of the immune system whose inner workings are still being defined. While most T cells respond to foreign proteins to protect the body, NK T cells are unique in that they respond to glycolipids, which are natural biochemicals made of linked fat and sugar. Prized for initiating a fast and vigorous immune response, NK T cells are emerging as a subject of significant scientific interest because of their potential for fighting bacterial infections and cancer. Kronenberg and Sellati have been among the nation's leaders in studying these cells. Kronenberg's laboratory was among the first to identify bacteria which naturally induce an immune response from the NK T cells. Thus far, he has identified two such bacteria- Borrelia burgdorferi and Sphingomonas species, a fairly benign bacteria found throughout the environment. However, he believes many other types of bacteria may also trigger the NK T cells. "This is an exciting possibility that needs to be further explored as it could lead to the development of treatments for many bacterial diseases." La Jolla Institute for Allergy and Immunology |
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| Related Lyme Disease Current Events and Lyme Disease News Articles On the Trail of a Vaccine for Lyme Disease: Yale Researchers Target Tick Saliva A protein found in the saliva of ticks helps protect mice from developing Lyme disease, Yale researchers have discovered. The findings, published in the November 19 issue of Cell Host & Microbe, may spur development of a new vaccine against infection from Lyme disease, which is spread through tick bites. Researchers to probe whether Lyme disease will follow spread of ticks across U.S. Potentially debilitating Lyme disease doesn't afflict people everywhere that the ticks harboring it are found. At least not yet. A five-university consortium led by a Michigan State University researcher wants to find out why. Inflammatory disease treatments will improve through the use of lipidomics According to the National Center for Chronic Disease Prevention and Health Promotion, 46 million Americans have arthritis. UI chemists' DNA biosynthesis discovery could lead to better antibiotics Combating several human pathogens, including some biological warfare agents, may one day become a bit easier thanks to research reported by a University of Iowa chemist and his colleagues in the April 16 issue of the journal Nature. Scientists discover new chemical reaction for DNA production in bacteria and viruses A team of researchers has discovered a new chemical reaction for producing one of the four nucleotides, or building blocks, needed to build DNA. Eugene-Springfield face Upper Willamette climate threats Effects of climate change projected this century for Oregon's Upper Willamette River Basin, including Eugene-Springfield, will threaten water supplies, buildings, transportation systems, human health, forests, and fish and wildlife, according to a report produced by the University of Oregon's Climate Leadership Initiative and the National Center for Conservation Science & Policy. A Natural, Alternative Insect Repellent to Deet Isolongifolenone, a natural compound found in the Tauroniro tree (Humiria balsamifera) of South America, has been found to effectively deter biting of mosquitoes and to repel ticks, both of which are known spreaders of diseases such as malaria, West Nile virus, and Lyme disease. Grazing animals help spread plant disease Researchers have discovered that grazing animals such as deer and rabbits are actually helping to spread plant disease - quadrupling its prevalence in some cases - and encouraging an invasion of annual grasses that threaten more than 20 million acres of native grasslands in California. New CU-Boulder study shows diversity decreases chances of parasitic disease A new University of Colorado at Boulder study showing that American toads who pal around with gray tree frogs reduce their chances of parasitic infections known to cause limb malformations has strong implications for the benefits of biodiversity on emerging wildlife diseases. Study: Bird diversity lessens human exposure to West Nile Virus A study by biologists at Washington University in St. Louis shows that the more diverse a bird population is in an area, the less chance humans have of exposure to West Nile Virus (WNV). More Lyme Disease Current Events and Lyme Disease News Articles |
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