Papers of the Month
By Sara Mishamandani Amolegbe
B vitamins may protect against epigenetic effects of air pollution
Taking B vitamins may help lessen the effects of fine particles, a common air pollutant, according to a new study published by NIEHS-funded researchers. The team demonstrated that B vitamin supplements prevented epigenetic changes, which affect the function of DNA without altering the original sequence of amino acids.
Ten healthy adult volunteers were exposed to clean air and given a placebo to check baseline responses. They were then given a placebo for 4 weeks and exposed for 2 hours to air containing particulate matter less than 2.5 micrometers in diameter (PM2.5). The experiment was repeated in the same individuals, with each volunteer taking a daily B vitamin supplement for 4 weeks before another exposure to PM2.5.
Without supplementation, researchers found that PM2.5 induced epigenetic changes in genes involved in inflammation and metabolism. According to the authors, B vitamin supplementation almost completely prevented these changes.
This pilot intervention trial highlights how vitamin B supplementation may reduce the adverse effects of PM2.5. It also provides insight into the role of epigenetic modifications associated with the health effects of air pollution.
Zhong J, Karlsson O, Wang G, Li J, Guo Y, Lin X, Zemplenyi M, Sanchez-Guerra M, Trevisi L, Urch B, Speck M, Liang L, Coull BA, Koutrakis P, Silverman F, Gold DR, Wu T, Baccarelli AA. 2017. B vitamins attenuate the epigenetic effects of ambient fine particles in a pilot human intervention trial. Proc Natl Acad Sci U S A 114(13):3503–3508. (Story)
New marker to identify aflatoxin B1 exposure
NIEHS grantees developed a way to determine whether liver cells have been exposed to aflatoxin B1 (AFB1), a fungal product that is a known liver carcinogen. Their new powerful DNA sequencing technique has the potential to identify mutations associated with AFB1 exposure long before cancer develops.
Mice exposed to aflatoxin 4 days after birth eventually developed liver cancer. The researchers sequenced DNA from the mice tumors and from liver cells before the tumors developed. Using a new genome sequencing technique, they identified patterns in DNA mutations associated with the AFB1 exposure. These mutation patterns emerged as soon as 10 weeks after exposure, before any signs of tumors.
The researchers compared the mutational profile of the aflatoxin-exposed mice to genetic sequences found in liver tumors in patients from around the world. They found that the signature of the mouse cells closely matched the signatures of 13 patients believed to have been exposed to aflatoxin through their diet.
According to the authors, this technique has promise for predicting whether someone exposed to AFB1 has a high risk of developing liver cancer, providing a potential opportunity for early detection and management.
Chawanthayatham S, Valentine CC 3rd, Fedeles BI, Fox EJ, Loebd LA, Levine SS, Slocum SL, Wogan GN, Croy RG, Essigmann JM. 2017. Mutational spectra of aflatoxin B1 in vivo establish biomarkers of exposure for human hepatocellular carcinoma. Proc Natl Acad Sci U S A 114(15):E3101–E3109.
3-D model simulates female reproductive tract and menstrual cycle
A new miniature 3-D model of the female reproductive tract and menstrual cycle can be used to study the effects of chemicals and drugs on the female reproductive system. NIEHS grantees developed the model, which fits in the palm of the hand and mimics a normal 28-day hormone cycle.
The new device, termed EVATAR, involves human tissue and 3-D models of the ovaries, fallopian tubes, uterus, cervix, vagina, and liver. A fluid and pumping method simulates the flow of blood between each of the organ systems. The organ models communicate with each other via secreted substances, such as hormones, replicating how organs work together in the body. EVATAR can be used to test secretion of hormones and interactions between organs during month-long experiments.
According to the authors, EVATAR will also help scientists understand endometriosis, fibroids, cancer, infertility, and other hormone-related diseases of the female reproductive tract. Because human tissue is integrated into the model, the system could potentially offer reproductive models to test individual differences in responses to drug treatments and susceptibility to chemicals.
Xiao S, Coppeta JR, Rogers HB, Isenberg BC, Zhu J, Olalekan SA, McKinnon KE, Dokic D, Rashedi AS, Haisenleder DJ, Malpani SS, Arnold-Murray CA, Chen K, Jiang M, Bai L, Nguyen CT, Zhang J, Laronda MM, Hope TJ, Maniar KP, Pavone ME, Avram MJ, Sefton EC, Getsios S, Burdette JE, Kim JJ, Borenstein JT, Woodruff TK.. 2017. A microfluidic culture model of the human reproductive tract and 28-day menstrual cycle. Nat Commun 8:14584. (Story)
Pest management education may reduce asthma symptoms
Teaching families how to reduce allergens shed by mice in their home is an effective way to reduce asthma symptoms in children and adolescents, according to NIEHS-funded researchers. In a new study, researchers compared professional pest management plus education with pest management education alone in households in Baltimore and Boston. Both groups experienced significant reductions in mice allergens and asthma symptoms, with no significant difference between the two approaches.
According to the authors, previous studies have shown that mouse proteins found primarily in urine can trigger allergic symptoms and are often present in low-income and urban neighborhoods in the United States. To determine whether pest management interventions reduce mouse allergens and asthma symptoms, researchers conducted a study of 361 children and adolescents with asthma and allergies to mice. Approximately half of the participants received professional pest management. Both groups received pest management education, written materials, and a demonstration of how to set traps and seal holes that could serve as entry points for mice.
About 40 percent of the households had a decrease in allergen levels of at least 90 percent. Both groups saw substantial improvements in asthma with reductions in mouse allergens. According to the team’s estimations, a 90 percent decrease in bedroom floor mouse allergens reduced maximum symptoms by 14 days per year.
Matsui EC, Perzanowski M, Peng RD, Wise RA, Balcer-Whaley S, Newman M, Cunningham A, Divjan A, Bollinger ME, Zhai S, Chew G, Miller RL, Phipatanakul W. 2017. Effect of an integrated pest management intervention on asthma symptoms among mouse-sensitized children and adolescents with asthma: a randomized clinical trial. JAMA 317(10):1027–1036.