Research Round Up

A Sunny Outlook on Rheumatoid Arthritis

Elizabeth Arkema, MD

A study has found that regular exposure to sunlight-specifically ultraviolet B (UVB)-may reduce the risk of developing rheumatoid arthritis.

Researchers looked at data from more than 135,000 nurses who participated in Nurses Health Study (NHS) and Nurses Health Study II. UVB levels were quantified using an assessment known as UV-B flux, which is a composite measure of UVB radiation based on latitude, altitude and cloud cover. Exposure was estimated based on state of residence.

There were 1,314 women who developed rheumatoid arthritis over the study period. Among nurses in the first NHS cohort, higher cumulative exposure to UVB was associated with a reduced risk of developing the disease. Those with the highest levels of exposure were 21 percent less likely to develop rheumatoid arthritis than those with the least.

However, no such association for UVB exposure was found among women in NHS II, who were younger than those in the first NHS.
 
"Differences in sun protective behaviors, such as greater use of sun block in younger generations may explain the disparate results," said Elizabeth Arkema, MD, BWH Division of Rheumatology, Immunology and Allergy, lead study author.

Although the findings add to the growing evidence that UVB exposure is associated with decreased risk of rheumatoid arthritis, the researchers note that further studies need to be done to understand the mechanisms behind this.

The study was published online on February 4, 2013, in Annals of the Rheumatic Diseases.

The Sound of Weight Gain

Amir Lahav, ScD, PhD

A research team led by Amir Lahav, ScD, PhD, BWH Department of Newborn Medicine, has found that exposure to biological maternal sounds while in an incubator may improve weight gain in very low-birth-weight infants (infants weighing less than 1,500 grams [3.3 pounds]).

The researchers compared a prospective treatment  group of 16 very low-birth-weight infants to a retrospective control group of 16 infants matched for sex, birth-weight, gestational age, fluid and caloric intake, and scores for neonatal acute physiology and illness severity.

Infants in the prospective treatment group received daily exposure to recorded maternal sounds during their entire stay in the neonatal intensive care unit. These sounds included the mother's speaking, reading and singing voice mixed with the biological recording of her heartbeat.

Emily Zimmerman, PhD, a postdoctoral fellow in the Lahav lab and first study author, observed that babies who were exposed to maternal sounds had a significantly faster rate of weight gain during the neonatal period (the first 28 days of life).

Very low-birth-weight infants receiving biological maternal sounds gained an average of 2.16 grams per kilogram more per day compared to their control counterparts who received routine exposure to hospital sounds (13.13 grams/kilogram/day vs. 10.97 grams/kilogram/day, respectively).

"It is possible that the soothing effects of the mother's voice led to an overall reduction in stress, anxiety, and restless states, which in turn, allowed the infant to preserve more energy and improve weight gain." said Lahav. Lahav notes that these promising results require further evidence from larger randomized studies.

The study was published online on February 4, 2013, in the American Journal of Perinatology.

Insights into the Human Immune Response to the Unimaginable

James Lederer, PhD

A research team led by James Lederer, PhD, BWH Department of Surgery, senior study author, developed a mouse model that closely mirrors how the human immune system would respond if exposed to radiation and injury from a radionuclear event.

They found that the immune system's response to radiation plus trauma injury differs significantly from radiation or trauma injury alone. According to the researchers, this is an important problem to address because history shows that a radionuclear explosion will cause both traumatic injuries and radiation exposures. 

Importantly, the research team developed this model in outbred mice rather than more commonly used inbred mice to better represent the human response to these complex injuries.  They found that mice that were exposed to radiation plus trauma had lower injury survival, as well as lower bacterial sepsis survival rates compared to mice with single injuries.

Moreover, radiation exposure caused dose-dependent losses of immune cells, but they found that B and T cells were more sensitive to radiation, while macrophages, dendritic cells and natural killer cells were more resistant. However, radiation alone and radiation with trauma did induce unique increases in the percentages of CD4+ regulatory T cells, as well as a subset of macrophages known as GR-1+ macrophages. Furthermore, mice exposed to radiation plus injury developed a sustained pro-inflammatory immune system phenotype for up to 28 days after injuries, especially in mice exposed to low radiation doses. 

"Although we do not want to believe that this type of a disaster will ever happen, we used this model and the information gained to develop treatments that could be given after a radionuclear event to protect people in harm's way," said Lederer. "Our ongoing research shows that it is possible to partially restore immunity by giving mice immune stimulants that target immune cell populations that survive these complex injuries.  Although it is not a happy topic, we can't ignore the possibility of a nuclear event. We need to be prepared and we hope that our research work will help."  

The study was published in the January 2013 issue of Radiation Research.