Parasitic worms may prevent Crohns disease by altering bacterial balance

first_img Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe The parasitic worms that lurk in some people’s intestines may be revolting, but they seem to forestall Crohn’s disease and other types of inflammatory bowel disease (IBD). A new study might explain how, revealing that the worms enable beneficial microbes in the intestines to outcompete bacteria that promote inflammation. The results could lead to new ways of treating gut diseases by mimicking the effects of the parasites.“It’s a beautifully done paper,” says immunologist Joel Weinstock of Tufts University in Boston, who wasn’t connected to the work. “It had not been previously shown that one of the mechanisms [of IBD] is through changes in the intestinal flora.”In people with IBD, inflammation in the digestive tract results in symptoms such as diarrhea and bleeding and can sometimes lead to intestinal obstructions or other severe complications. Because parasitic worms, or helminths, can be harmful, they appear to be unlikely allies against these diseases. “They are called parasites for a reason,” says immunologist Ken Cadwell of the New York University School of Medicine in New York City, a co-author on the new study. However, IBD is rare in parts of the world where helminths are prevalent, and it is surging in more developed countries, where few people now carry the intestinal intruders. That difference suggests, researchers say, that they are protective. Click to view the privacy policy. Required fields are indicated by an asterisk (*) Sign up for our daily newsletter Get more great content like this delivered right to you! Countrycenter_img Email To determine how the worms could be our frenemies, Cadwell and colleagues tested mice with the same genetic defect found in many people with Crohn’s disease. Mucus-secreting cells in the intestines malfunction in the animals, reducing the amount of mucus that protects the gut lining from harmful bacteria. Researchers have also detected a change in the rodents’ microbiome, the natural microbial community in their guts. The abundance of one microbe, an inflammation-inducing bacterium in the Bacteroides group, soars in the mice with the genetic defect.The researchers found that feeding the rodents one type of intestinal worm restored their mucus-producing cells to normal. At the same time, levels of two inflammation indicators declined in the animals’ intestines. In addition, the bacterial lineup in the rodents’ guts shifted, the team reports online today in Science. Bacteroides’s numbers plunged, whereas the prevalence of species in a different microbial group, the Clostridiales, increased. A second species of worm also triggers similar changes in the mice’s intestines, the team confirmed.To check whether helminths cause the same effects in people, the scientists compared two populations in Malaysia: urbanites living in Kuala Lumpur, who harbor few intestinal parasites, and members of an indigenous group, the Orang Asli, who live in a rural area where the worms are rife. A type of Bacteroides, the proinflammatory microbes, predominated in the residents of Kuala Lumpur. It was rarer among the Orang Asli, where a member of the Clostridiales group was plentiful. Treating the Orang Asli with drugs to kill their intestinal worms reversed this pattern, favoring Bacteroides species over Clostridiales species, the team documented.Cadwell and colleagues also asked whether Clostridiales and Bacteroides microbes were at odds in other people. They analyzed two sets of data on the frequencies of different intestinal microbes, which include results for healthy U.S. residents and kids in North America who have IBD. They saw the same relationship—when Clostridiales species are up, Bacteroides varieties are down, and vice versa.The study’s findings suggest that parasitic worms deliver their benefits indirectly through their impact on the microbial mixture in the intestines. Worms are “having an anti-inflammatory effect by kicking out something that is inflammatory,” Cadwell says. Members of the Clostridiales group may get a boost when worms are around, he says, because the intestines produce more mucus, which the bacteria feast on.“This is a good proof of concept,” says immunologist Gabriel Nunez of the University of Michigan, Ann Arbor, who wasn’t connected to the research. It supports “the principle that some of these diseases may be related to changes in the microbiome.” But he cautions that researchers still need direct evidence that Bacteroides species are responsible for Crohn’s disease.Turning the results into a treatment for IBD could be difficult. Two recent clinical trials of helminth treatment for Crohn’s disease, in which participants drank a solution containing the worms’ eggs, stopped early because the results were disappointing. These studies may not be the last word, however. Cadwell says that worm therapy might work in the roughly 30% of Crohn’s patients who have the same genetic flaw as the mice. And Weinstock notes that if researchers can determine how the parasites trigger the shift in microbe composition, “we may be able to bypass the worms and develop a small molecule drug to get the effect in a safe way.”last_img read more