Skin Fat Helps Protect Against Infections, Study Finds

Fat cells just under a person's skin may be the first responders to invading bacteria, buying time until the white blood cells arrive at a wound site, according to a new study.

The new findings suggest that the task of fighting infections is not solely the responsibility of the immune system, the researchers said. Moreover, fat cells may fight infections by producing antimicrobial compounds, lab experiments in mice and human fat cells showed.

"That was totally unexpected," study co-author Dr. Richard Gallo, chief of dermatology at the University of California, San Diego School of Medicine, said in a statement. "It was not known that [fat cells] could produce antimicrobials, let alone that they make almost as much" as immune system cells, he said.

In the study, the researchers exposed mice to the bacterium methicillin-resistant Staphylococcus aureus (MRSA), a type of staph bacteria that is found on human skin and is resistant to several antibiotics. MRSA can cause hard-to-treat — and even deadly — infections in people. [6 Superbugs to Watch Out For]

When the skin is cut and exposed to pathogens, the immune systemsends specialized white blood cells, such as neutrophils, to the wound site to kill the bacteria entering the skin. But it takes time for these cells to reach the site of injury.

In the experiments in mice, the researchers found that the layer of fat under the skin at the site of an infection thickened, and that the fat cells produced an antimicrobial compound called cathelicidin. These findings suggest that these fat cells can directly sense the staph bacteria and respond accordingly, the researchers said.

In addition, mice that lacked healthy fat cells under the skin suffered more frequent and severe infections with MRSA, according to the study, published today (Jan. 2) in the journal Science.

However, the findings don't mean that having too much fat in the body will bring better protection against infections. In fact, obesity or insulin resistance could result in having fat cells that don't respond as they should, and may actually lower a person's defense against infections, the researchers said. This could explain the results of previous studies that found that obese people may be at higher risk for skin infections, the researchers said.

Drinking Declines with Age, UK Study Finds

People tend to drink less as they get older, but how much a person's alcohol intake declines over time depends on both their overall health and whether they have a partner, a new report from the U.K. finds.

People in poor health tend to have a steeper drop in their drinking as they age than those in better health, the researchers found. It's likely that older adults with deteriorating health drink less because it's difficult to meet their friends for drinks if they're not feeling well, or because alcohol may interact with medicationsprescribed by their doctors, the researchers said.   

For those who lose their partner, either through a separation or death, the effect on drinking depends on the person's gender: Women who lose their partner show faster decline in their drinking compared with women who don't lose their partner, whereas men who lose their partner show a slower decline in drinking than men who remain partnered up.

The study challenges the assumption that the loss of a partner often leads to alcohol misuse in aging adults, the researchers said. "In particular, our analysis of drinking behaviors demonstrates that change in partnership status for women is associated with a reduction in alcohol consumption," Clare Holdsworth, a professor of social geography at Keele University in England, said in a statement.

In their report, the researchers looked at surveys of more than 4,500 men and women living in the U.K., examining how people's drinking habits changed as they grew older. The study participants were all over age 45 at the start, and every two years, they answered survey questions about their life, including their wealth, health, education levels and life events, such as retirement or the passing of a spouse.

The researchers also found that men who are wealthy, single and educated drink the most of any group. It's possible these men have more disposable income to spend on alcohol, as well as more social engagements, especially because they are single, the researchers said. Men who fit into this group drank, on average, an equivalent of 24 small glasses of wine a week.

In contrast, when the men reached retirement age, those who had poor or deteriorating health or less education tended to drink an equivalent of five small glasses of wine weekly, the researchers said. Similarly, women with lower levels of education and poor health tended to have the lowest alcohol intake throughout the study.

Women over age 50 who lost a partner also drank an average of 16 percent less at the end of the study than they did at the beginning, the researchers found. By comparison, women who stayed in a relationship showed an 11 percent drop in alcohol consumption over the same period.

"Our findings suggest that the group most at risk of heavy drinking in later life are older single men with high levels of education and above-average wealth," Holdsworth said.  

But men in this group might not identify their drinking as problem behavior, making it difficult for health organizations to target them for intervention, she said. "Also this group are less likely to have poor health in the short term, hence the need for intervention might not be apparent."

The study, which started surveying people in 1998 and 2000, found that, on average, men older than 45 drank 14 small glasses of wine a week, whereas women of the same age drank seven small glasses of wine a week. The researchers considered a small glass of wine (11 percent alcohol by volume) to be the equivalent of about a half cup (125 milliliters).

The number of men who said they did not drink grew from 6 percent to 18 percent from the beginning to the end of the study. For women, that percentage grew from 18 percent to 26 percent over the course of 10 years.