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Gut Bacteria Dramatically Boosts Cancer Immunotherapy

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Science has confirmed that a balanced gut—where good bacteria outnumber bad—is often linked to a stronger immune system. Now, researchers in the lab of Thomas Gajewski, professor of pathology and medicine at the University of Chicago (UC), have discovered that good bacteria can also dramatically amplify the effects of cancer immunotherapy treatments. Their results are published in the November issue of the journal Science.

When the researchers introduced a particular strain of bacteria into the digestive tracts of mice with melanoma, they were startled to find it boosted the animals’ immune systems so effectively, the tumor-reducing effects were comparable to anti-cancer drugs known as checkpoint inhibitors, which keep the immune system from becoming overactive.

These inhibitors, however, which can be dramatically effective at reducing tumors when they do work, only do so in a third or fewer patients who use them.

The researchers already knew that gut bacteria had been shown to effect systemic immunity, but they came to their exciting discovery of its effect in cancer treatment by accident. Mice purchased from Jackson Laboratory (JAX) had a more notably robust immune response to small tumors implanted under their skin. Mice from Taconic Biosciences (TAC), however, showed weak immune response. When researchers put the mice from both sources together for three weeks, these discrepancies disappeared. They suspected that the mice shared microbes that enhanced their immunity.

“Gut bacteria influence the differentiation and function of systemic T cell subsets so that they respond faster and more efficiently to stimuli,” says lead author Ayelet Sivan, a Ph.D. student in Gajewski’s lab who designed and executed the experiments.

To test their theory that the microbes were responsible for the improved immune response, they transferred fecal matter from JAX mice to the stomachs of TAC mice, with positive results. The treated TAC mice had stronger immune responses and slower tumor growth.

When they compared the bacterial transfer effects with the effects of a checkpoint inhibitor drug, they found that the bacteria treatment was just as effective.

As soon as five days following the start of fecal transfer, Sivan says, “We saw that there was a delay in tumor outgrowth and that there was a boost in tumor specific immune responses.”

In their search for which specific bacteria made the difference, one genus stood out from over 254 strains: Bifidobacterium. Once identified, they treated the TAC lower-immunity mice with Bifidobacterium directly, without fecal transfer, and still, the immune boosting, tumor-fighting results remained high. 

As for how this occurred, the researchers suspect that Bifidobacterium, which appear to have colonized a compartment in the mouse intestines, interacted with roaming dendritic cells, which hunt for threats and present them to T cells. In response, the T cells attacked the tumors.

Sivan tells mental_floss that their study focused specifically on melanoma cancer because “it is well established that immunotherapies can be effective in melanoma, and that the immune response plays an important role in the control of melanoma growth and treatment.” But future research will look at other cancers that benefit from immunotherapies, as well as other bacteria strains. “There are many open questions as to the mechanism and signals through which Bifidobacterium leads to improved antitumor immunity, which may lead to novel therapies that may eventually replace the use of the bug itself,” she says.

They are eager to get to the stage where the bacteria can be tested for efficacy in humans and will continue to research other bacteria strains and their effect on antitumor immune responses. 

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The Surprising Link Between Language and Depression
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Skim through the poems of Sylvia Plath, the lyrics of Kurt Cobain, or posts on an internet forum dedicated to depression, and you'll probably start to see some commonalities. That's because there's a particular way that people with clinical depression communicate, whether they're speaking or writing, and psychologists believe they now understand the link between the two.

According to a recent study published in Clinical Psychological Science, there are certain "markers" in a person's parlance that may point to symptoms of clinical depression. Researchers used automated text analysis methods to comb through large quantities of posts in 63 internet forums with more than 6400 members, searching for certain words and phrases. They also noted average sentence length, grammatical patterns, and other factors.

What researchers found was that a person's use (or overuse) of first-person pronouns can provide some insight into the state of their mental health. People with clinical depression tend to use more first-person singular pronouns, such as "I" and "me," and fewer third-person pronouns, like "they," "he," or "she." As Mohammed Al-Mosaiwi, a Ph.D. candidate in psychology at the University of Reading and the head of the study, writes in a post for IFL Science:

"This pattern of pronoun use suggests people with depression are more focused on themselves, and less connected with others. Researchers have reported that pronouns are actually more reliable in identifying depression than negative emotion words."

What remains unclear, though, is whether people who are more focused on themselves tend to depression, or if depression turns a person's focus on themselves. Perhaps unsurprisingly, people with depression also use more negative descriptors, like "lonely" and "miserable."

But, Al-Mosaiwi notes, it's hardly the most important clue when using language to assess clinical depression. Far better indicators, he says, are the presence of "absolutist words" in a person's speech or writing, such as "always," "constantly," and "completely." When overused, they tend to indicate that someone has a "black-and-white view of the world," Al-Mosaiwi says. An analysis of posts on different internet forums found that absolutist words were 50 percent more prevalent on anxiety and depression forums, and 80 percent more prevalent on suicidal ideation forums.

Researchers hope these types of classifications, supported by computerized methods, will prove more and more beneficial in a clinical setting.

[h/t IFL Science]

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Just 5 Alcoholic Drinks a Week Could Shorten Your Lifespan
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Wine lovers were elated when a scientific study last year suggested that drinking a glass of wine a day could help them live longer. Now a new study, published in The Lancet, finds that having more than 100 grams of alcohol a week (the amount in about five glasses of wine or pints of beer) could be detrimental to your health.

Researchers from the University of Cambridge and the British Heart Foundation studied the health data of nearly 600,000 drinkers in 19 countries and found that five to 10 alcoholic drinks a week (yes, red wine included) could shave six months off the life of a 40-year-old.

The penalty is even more severe for those who have 10 to 15 drinks a week (shortening a person’s life by one to two years), and those who imbibe more than 18 drinks a week could lose four to five years of their lives. In other words, your lifespan could be shortened by half an hour for every drink over the daily recommended limit, according to The Guardian, making it just as risky as smoking.

"The paper estimates a 40-year-old drinking four units a day above the guidelines [the equivalent of drinking three glasses of wine in a night] has roughly two years' lower life expectancy, which is around a 20th of their remaining life," David Spiegelhalter, a statistician at the University of Cambridge who was not involved with the study, tells The Guardian. "This works out at about an hour per day. So it's as if each unit above guidelines is taking, on average, about 15 minutes of life, about the same as a cigarette."

[h/t The Guardian]

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