上次在某个帖子里提到一个观点: “还是听那个PI说,有人把免疫系统分为两大分支,一支负责监视寄生虫病原体什么的 ,另一支和过敏啥的相关;这两分支相互平衡。最近有报道有人在过敏还是哮喘患者体 内注射寄生虫(其中包括他/她自己,这让我想起了Marshall和Morris),来加强前一 个分支抑制后一个分支,结果治好了过敏还是哮喘。。。下一步他/她要做大规模的试 验。。。这个只是听说而已,等他回来了,还需要查证查证。” 那个PI回来了,问他要消息来源,他说只是听到新闻,不知道是不是正式的文章发表。 于是自己查了一查,他说的那个目前还没找到,但找到几个有意思的报道。 先贴个这个:What Do Worms Have to Do With Asthma? http://news.sciencemag.org/sciencenow/2011/02/what-do-worms-hav WASHINGTON, D.C.—Parasites get a bad rap for a good reason. They cause a litany of diseases with a terrifying host of symptoms. But mounting evidence suggests that they can also prevent disease. And now there’s genetic evidence to suggest that’s true. New research presented here yesterday at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW) finds that a gene associated with increased risk of asthma is also linked to resistance against a parasitic worm. Scientists have long suspected that allergies and asthma—common in the developed world and relatively rare in poor countries—are the result of lack of exposure to microbes. This 2-decade-old idea, called the hygiene hypothesis, suggests that lack of exposure to dangerous parasites in childhood makes the adaptive arm of the immune system more likely to overreact when it comes into contact with benign allergens. Kathleen Barnes, an anthropologist and genetics expert at Johns Hopkins University in Baltimore, Maryland, and her colleagues have been studying the relationship between asthma and one particular parasitic worm, Schistosoma mansoni, in Conde, a cluster of rural fishing villages on the coast of Brazil. The worm is common in the region, and up to 85% of residents are exposed to it. Previous studies have shown that, in areas like Conde, where parasitic worms are endemic, individuals who produce the most worm-specific antibodies—in particular, an antibody called IgE, which triggers inflammation—tend to be the most resistant to worm infection. According to Barnes’s research, that resistance appears to be about 30% heritable. The researchers noted that after they administered medication to rid Conde’ s residents of worms, the incidence of asthma and allergy symptoms increased . So Barnes hypothesized that the mutations that help individuals fend off parasitic worms might be the same mutations that make them susceptible to asthma and allergies. If an individual produces a lot of IgE in response to a worm, he or she might also produce a lot of IgE in response to an allergen. The team collected blood and stool samples from 850 people in Conde. They tested their blood for antibodies to the worm to gauge their immune response and searched their stool for worm eggs to determine how heavily they were infected. The researchers decided to focus on genes that have been linked to asthma risk. They were particularly interested in IL-33, a gene linked to inflammation that is overexpressed in the lung tissue of asthmatics compared with people without the disease. “IL-33 stands as one of the strongest candidate genes for asthma to date,” Barnes says. Barnes and colleagues selected 23 genetic markers throughout the gene and tested whether any of them were associated with worm resistance in the residents of Conde. Five of them did show a strong association, and those happened to be the exact same markers that are associated with asthma. “And what we’re most excited about is that the relationship is inverse,” Barnes says. “So a [gene variant] that conferred risk to asthma confers protection against [worm infection].” The researchers posit that natural selection might favor mutations that protect against worm infection and that those same mutations might inadvertently increase the risk of other diseases, such as asthma. The researchers haven’t yet found the exact mutation responsible for the worm resistance and asthma susceptibility. To find that, they’ll have to “drill down deeper,” Barnes says. She speculates that the culprit may be a mutation located in a genome region that regulates activity of the IL-33 gene. Jennifer Ingram, a cell biologist who studies asthma at Duke University in Durham, North Carolina, says the finding that deworming medication increased the incidence of asthma symptoms is “striking.” She adds that Barnes’s work is important because it points the field toward molecular mechanisms that might contribute to asthma. David Van Sickle, a medical anthropologist at the University of Wisconsin, Madison, who presented during the same session as Barnes, points out that the global prevalence estimates for asthma are based largely on asking people whether a physician has ever told them they have asthma. But diagnoses vary from culture to culture. Van Sickle found, for example, that physicians in India are much less likely than doctors in Wisconsin to diagnose a person who has clear symptoms of asthma with the disease. So the true prevalence of asthma in India or other countries could be higher or lower than current estimates. Changes in the prevalence of asthma wouldn’t necessarily nullify the hygiene hypothesis, he says, but they could complicate the picture. Still, he says Barnes's work is “elegant.” 再贴个这个:Eat Your Worms: The Upside Of Parasites http://www.npr.org/2010/12/02/131753267/eat-your-worms-the-upsi For years evidence has been mounting that intestinal parasites can actually be a good thing for people with inflammatory bowel disease because certain parasitic worms seem to help the intestine heal. Now scientists think they've found at least one reason why this is so, thanks to a man who has spent years treating his own bowel disease with worms. Years ago, that man placed a call to P'ng Loke, a parasitologist who was then working at the University of California, San Francisco. "He had moved into the Bay Area and basically was looking for someone who works on worms, and so he called me and convinced me to have lunch with him, " Loke recalls. Over lunch, the man told Loke a remarkable story about how he'd recovered from ulcerative colitis, a bowel disease in which the immune system appears to attack the lining of the colon, causing devastating ulcers. And for this man, Loke says, the usual treatments, including steroids, hadn't helped. "So he was being faced with the options of really severe immune suppressants or a colectomy," the removal of his colon, Loke says. But this man was a young entrepreneur with his own ideas. He'd run across the work of scientist Joel Weinstock who is now at Tufts Medical Center in Boston. Weinstock had done something that seemed bizarre: He had started using parasitic worms to treat people with ulcerative colitis. Radiolab Could parasites be the shadowy hands that pull the strings of life? Radiolab uncovers a world full of parasites and explores nature's moochers, with tales of lethargic farmers, zombie cockroaches and even mind-controlled humans (kinda, maybe). And we examine claims that some parasites may actually be good for you. Listen To Radiolab's "Parasites" "So people would swallow microscopic eggs, and the eggs then hatch within the GI tract, and that living agent that comes out is capable to interact with the host's immune system," Weinstock says. Weinstock thought these parasites might help because in places where they are common, inflammatory bowel disease is rare. His hunch turned out to be correct: The people in his study got better. Worms A Key Factor In Healing Loke says that was good enough for the entrepreneur in San Francisco, who started looking for his own source of parasitic worm eggs. "He managed to find a parasitologist in Thailand who was willing to help him obtain these eggs, and then he infected himself," Loke says. And he too got better and was feeling fine by the time he had lunch with Loke. But he wanted scientists to figure out why the cure had worked. So he offered to let researchers study his intestine over the next few years. During that time, the worms began to die off and the man's disease came back . So he took another dose of worm eggs and got better again. Through it all, Loke and his colleagues were collecting blood and tissue samples from the man. An illustration of the life cycle of Trichuris trichiura Enlarge Public Health Image Libarary/CDC A diagram of the life cycle of the Trichuris trichiura parasite. Enlarge the image for a more detailed description. An illustration of the life cycle of Trichuris trichiura Public Health Image Libarary/CDC Infections of Trichuris trichiura, commonly called human whipworm, are more frequent in areas with poor sanitation and tropical weather. This illustration, from the CDC's Division of Parasitic Diseases and Malaria, explains the life cycle of the parasite. (1) Eggs are passed with the stool. (2) In soil, the eggs divide into two cells, then further divide (3) until they become embryonated (4) and are capable of infecting. Eggs are infective between two weeks and a month and can be ingested via soil-contaminated hands or food. They hatch in the small intestine (5), and adult worms attach themselves to the walls of the colon (6), where they can live for about a year. Female worms shed 3,000 to 20,000 eggs per day. "What we found was that after worm infection, the regions of the colon that were previously not making mucus, were now making mucus again," he says. That's a key factor in healing, and it looked like the mucus came back because the worms were causing the body to produce a substance called IL-22. Weinstock says that makes sense. "This is a molecule that promotes epithelial growth and healing and perhaps does other things to the immune system that would be potentially beneficial, " he says. Weinstock says other studies suggest parasites can regulate the immune system in ways that prevent it from going wild and attacking healthy tissue, and he says it's likely that human evolution took that into account. "Humans have had parasites ever since we evolved from living in caves or swinging from trees or however it used to be, and disrupting these relationships probably had consequences," he says. Weinstock says drug companies are now trying to create parasites that would actually be approved by the FDA for treating inflammatory bowel disease. The research appears in the journal Science Translational Medicine. 今天比较无聊,发个帖子抛砖引玉。^_^