May 13, 2015

A May 12 article about the work of nutrition researcher Dr. Melinda Beck, written for Endeavors magazine by Susan Hardy, is excerpted below. The complete article is available on Endeavors’ website.

Dr. Melinda Beck

Dr. Melinda Beck

The 2014–2015 flu season was a tough one, says Melinda Beck, PhD, professor and associate chair of the nutrition department at UNC’s Gillings School of Global Public Health.

Beck studies the relationship between nutrition and immunology.

When people get the flu despite being vaccinated, it often is because viruses mutate quickly. We can’t control the flu’s super-fast evolution. But Beck’s lab found evidence that we can control how well our bodies make use of the vaccine—by controlling our weight.

At UNC’s Family Medicine Center, when patients come in for a flu shot, Beck’s study coordinator asks them to participate in a study and give two blood samples, the first before the shot and the second, 30 days later.

At 30 days out, blood from normal-weight people and obese people looks about the same, Beck said. Human antibodies respond to the inactivated flu virus in the vaccine, preparing to fight it off if it turns up again in live form.

But the following year, when a patient arrives for his or her next flu shot, the lab draws blood one more time. This is when the differences really show up.

Dr. Justin Milner

Dr. Justin Milner

Justin Milner, PhD, formerly a nutrition doctoral student working with Beck at the Gillings School, and the lab found that people with a normal body-mass index still have antibodies against the previous year’s flu – not enough to provide good protection for the next flu season, but some. In people with obesity, those antibodies have declined, Beck said.

Overall, people who received the flu vaccine in 2014 lowered their chances of getting influenza by only about 23 percent, according to the Centers for Disease Control and Prevention. That number might turn out to be even lower for people who are obese, according to research from Beck’s lab.

“If you’re obese and you’re vaccinated in September, maybe your antibodies have started dropping by the time you see flu in March,” Beck said. “So maybe you need to be vaccinated closer to when flu is actually circulating. Or maybe you need a stronger vaccine.”

If the virus makes it past the antibodies, the body has another line of defense. T cells kill any cells in the body infected by the virus. The flu vaccine primes these T cells to recognize flu and fight when it appears. But when you’re obese, there are problems with your T cells too, Beck said.

Back in the 2009 H1N1 pandemic, researchers noticed that obese people were more likely than normal-weight people to die—not just from H1N1, but from any type of flu. Most people survive even severe flu, as long as they get medical care – but most of us don’t head for the hospital as soon as we start feeling sick.

What if a person could tell early whether the flu warrants a hospital visit?

Milner found that just 24 hours after infection with flu, T cells from obese mice react differently than T cells from normal-weight mice. This leads Beck to imagine a drugstore test, similar to a home pregnancy test, that one could take as soon as flu is suspected. The test might measure certain activity of T cells and advise a person to go to the emergency department if the T cells don’t seem to be working well.

First, Beck’s lab has to determine what’s going on with T cells in obesity.

“When T cells are resting and floating around your body, they use fatty acids as a fuel source,” she said. “When you’re revving up to fight infection, they use glucose as fuel.”

One of her theories is that obesity interferes with immune cells’ ability to make the switch from running on fatty acids to glucose.

As the number of people with obesity increases, we need to know a lot more about obesity and the immune system, Beck said. It’s not just about the flu—she expects a wave of new research showing that as we get larger, we’re making it harder for our immune systems to fight off all types of disease.

Read the original article here.

Gillings School alumnus Dr. Justin Milner is now a postdoctoral fellow at the University of California in San Diego. His research won a 2015 Graduate Education Advancement Board Impact Award for valuable discoveries of direct benefit to North Carolina.


Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or dpesci@unc.edu
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