Science Concentrates NEUROSCIENCE
Blocking an immune system protein in mice reduces itchiness
POLLUTION
A casual brush with poison ivy can cause agonizing itching for an estimated 10 to 50 million Americans every year. But exactly how the plant inflicts such misery is still somewhat of a mystery. By exposing mice to poison ivy’s oily allergen urushiol, Sven-Eric
Plastics lure seabirds by smell
Poison ivy leaves change color in autumn. Jordt of Duke University and colleagues have now pinpointed a molecular pathway that helps transmit an itch signal through nerve cells. Antihistamines and corticosteroids are commonly prescribed to people with a poison ivy rash. But “the antihistamines just don’t work,” Jordt says, and although steroids help with inflammation, they’re ineffective against itch. “So from all perspectives, it is necessary to revisit the mechanisms and identify a more efficient treatment,” he adds. The researchers looked for genes that were transcribed at higher levels in mice
whose skin was brushed with urushiol compounds compared with nonexposed mice (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1606608113). Unsurprisingly, several genes involved in inflammation were upregulated in the urushiol-exposed mice. But the team focused on one particular gene that codes for the protein interleukin-33, previously associated with itchy skin conditions such as psoriasis. When the researchers gave itchy, urushiol-exposed mice antibodies against IL-33, the mice slowed their scratching considerably. Similarly, an antibody against IL-33’s receptor, ST2, which is located on sensory neurons that connect to the animals’ skin, also reduced scratching. Ethan A. Lerner, a dermatologist studying itch at Massachusetts General Hospital, calls the study “both surprising and not surprising,” because researchers suspected a link such as this one existed even though they didn’t know the specifics. “The immune system and the nervous system are talking to each other all the time,” he says. Unrelated to the Duke group’s work, antibodies against IL-33 and ST2 are the stars of two current clinical trials. AnaptysBio hopes to treat atopic dermatitis, peanut allergies, and asthma after finishing Phase I trials, and Genentech’s Phase II trial focuses on asthma and chronic obstructive pulmonary disorder. Next, Jordt’s team hopes to work with clinicians to see if they can detect IL-33 in humans with poison ivy.—RYAN CROSS
BY THE NUMBERS
9.7 million
Number of barrels of finished motor gasoline consumed per day in the U.S. during June 2016, according to the U.S. Energy Information Administration. This is a new high, surpassing the record 9.6 million barrels per day consumed in the U.S. during July 2007. At the same time, drivers in the U.S. travelled a record 15 billion km in their vehicles per day during the summer of 2016, up 6.4% from the summer of 2007. Taken together, these trends suggest that the new gasoline consumption record would be even higher if not for improved vehicle fuel economy. 8
C&EN | CEN.ACS.ORG | NOVEMBER 14, 2016
When birds eat plastic that pollutes marine environments, they suffer a variety of debilitating health problems. Researchers have wondered why the animals are drawn to feed on ocean plastic, which doesn’t look like standard food. Now a team led by Gabrielle A. Nevitt and Matthew S. Savoca at the University of California, Davis, reports that plastic floating on the ocean surface is easily fouled by dimethyl sulfide-producing algae (Sci. Adv. 2016, DOI: 10.1126/ sciadv.1600395). Birds in the Procellariiformes order, which includes petrels (shown) and albatrosses, use the aroma of dimethyl sulfide as a dinner cue signalS H3C CH3 ing that there’s nutrient-rich Dimethyl sulfide food nearby. So when fouled ocean plastic debris smell of dimethyl sulfide, these birds are drawn to consume it. The team tested 4- to 6-mm-diameter plastic beads made from common plastic polymers—namely high-density polyethylene, low-density polyethylene, and polypropylene. After being stored in ocean water, the plastic debris developed algal films and an aroma of dimethyl sulfide within a month at levels several orders of magnitude higher than the birds’ detection threshold. The results “point to remediation strategies, including increasing antifouling properties of consumer plastics,” note the researchers, especially because other marine organisms also use dimethyl sulfide as a dinner cue.—SARAH EVERTS
CREDIT: ETHAN A. LERNER (LEAVES); J. J. HARRISON (BIRD)
New route for taming poison ivy’s itch
