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  • [♪ INTRO]

  • Measles, mumps, and polio, these are things we can prevent with a vaccine.

  • But scientists are looking to add a surprising entry to that list: Type 1 diabetes.

  • Which, unlike the others, is not an infectious disease.

  • You can't share a sugar-free soda with your diabetic friend

  • and suddenly lose your ability to produce insulin.

  • It just doesn't work like that.

  • And usually, infectious diseases are the ones we can target with vaccines.

  • So how would a diabetes vaccine even work?

  • Well, type 1 diabetes, or T1D for short, is a chronic, irreversible condition,

  • typically diagnosed in children,

  • where certain people's bodies do not make the insulin they need

  • to control sugar in their bloodstream.

  • And that's different from type 2 diabetes, where patients' bodies typically become resistant to insulin

  • so it can't effectively manage blood sugar levels.

  • In type 1, they just don't make it in the first place.

  • Their immune system has turned on the rest of their body

  • and destroyed the cells in their pancreas responsible for making insulin.

  • For a long time, the trigger for this destruction has been a big question mark.

  • In recent years, scientists have identified genetic risk factors that increase a person's risk for T1D.

  • But these factors can't cause the disease alone.

  • Nor can they explain all the weird things public health scientists have found when studying T1D.

  • Like the fact that there are certain times of year

  • where more people get diagnosed with this chronic disease than other times,

  • not something usually chalked up to genetics.

  • So, with genetic factors failing to explain the full picture,

  • scientists have looked to the environment for additional causes.

  • They have investigated links to vitamin deficiency, potential dietary causes, and even pancreatic toxins.

  • But one of the most compelling explanations has to do with viruses.

  • Specifically that a class of viruses called enteroviruses,

  • which typically infect your GI tract, could induce T1D.

  • It's thought that they could somehow cause an immune response

  • that makes the body destroy those insulin-producing cells.

  • And this could be the key to a T1D vaccine.

  • Because while T1D is not infectious, viruses are.

  • And if these viruses induce T1D, it could open the door to using vaccines to grant immunity to those viruses,

  • which in turn, could prevent the development of T1D.

  • Over the last fifty years, several studies have been able to show a causal connection

  • between enteroviral infections and the induction of T1D, at least in mice.

  • But this connection has been much harder to show in humans,

  • partly because human subjects are just more difficult to study.

  • In order to prove that enteroviruses cause T1D,

  • you have to demonstrate that a group of infants who were genetically predisposed to T1D

  • were also infected with enterovirus.

  • That's before they were diagnosed with T1D.

  • And of course we can't infect human babies with viruses.

  • So, instead you have to wait until the babies naturally get infected,

  • which is difficult because most enteroviruses don't cause symptoms.

  • Parents don't generally show up at the doctor when their baby doesn't seem sick.

  • Neither do doctors usually think to look for a virus that's not doing anything.

  • Instead, you have to routinely collect samples from babies' poop and check them for enterovirus genes.

  • But, as researchers soon discovered, enterovirus genes can't always be found during an infection.

  • You need to check a bunch of times to catch them.

  • So in 2017, after a couple successful studies, several more failed ones, and a whole lot of baby poop,

  • the largest study to date settled the score with two important findings.

  • First, it showed that babies who are genetically susceptible to T1D

  • also have higher rates of enterovirus infection.

  • And second, it found that months after those infections,

  • the T1D-predisposed babies started producing certain auto-immune cells

  • which are known to attack the pancreas and cause T1D.

  • That's a pretty strong case.

  • And now that a strong connection has been shown in multiple studies,

  • it opens the door to vaccine research to prevent these infections.

  • That research has already begun.

  • One vaccine being studied in mice targets a specific enterovirus called CVB.

  • In a small study published in 2018, researchers administered the vaccine

  • to 7 mice carrying the genetic risk factors for T1D.

  • And all seven were protected from developing it.

  • News reports have claimed this CVB vaccine is set to enter human clinical trials soon,

  • but it could be years before they start the study or have results.

  • But that said, a group of scientists in Finland had the idea to try a shortcut.

  • See, polio is an enterovirus, and we already have a vaccine for it that we know is safe and effective.

  • They published a study in 2018 which looked at whether the poliovirus vaccine could prevent T1D,

  • but unfortunately, they found it had no protective effect.

  • So thus far, we don't have an anti-diabetes vaccine that works in humans.

  • But the CVB vaccine could work out,

  • and maybe someday we'll be able to look at type 1 diabetes as a disease of the past.

  • Thanks for watching this episode of SciShow.

  • And we want to thank all of our patrons for making this and every other episode that we make possible.

  • The fact that you guys help us make free videos for everyone is just super extra rad.

  • If you're interested in joining this cool group of people, head over to patreon.com/scishow.

  • [♪ OUTRO]

[♪ INTRO]

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ワクチンは1型糖尿病を予防できるのか? (Could a Vaccine Prevent Type 1 Diabetes?)

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    林宜悉 に公開 2021 年 01 月 14 日
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