How Gut Bacteria May Affect The Outcome Of Cancer Immunotherapy

In the ongoing development of cancer immunotherapy, as well as our still developing understanding of the human immune system, there’s always been a bit of massive elephant in the room. The thing about human bodies is that they’re not just human cells, but also consist of trillions of bacteria that mostly live in the intestines. What effect these bacteria have on the immune system’s functioning and from there on immunotherapies was recently investigated by [Tariq A. Najar] et al., with an article published in Nature.

The relevant topic here is that of antigenic mimicry, involving microbial antigens that resemble self-antigens. Since these self-antigens are a crucial aspect of both autoimmune diseases and cancer immunotherapy there is considerable room for interaction with their microbial mimics. Correspondingly these mimics can have considerable negative as well as positive implications, ranging from potentially triggering an autoimmune condition to hindering or boosting cancer immunotherapy.

In this study mice were used to investigate the effect of such microbial interference, in particular focusing on immune checkpoint blockade (ICB), which refers to negative feedback responses within the immune system that some cancers use to protect themselves. In some immunotherapy patients ICB inhibiting using e.g. anti programmed cell death protein (anti-PD-1) treatment does not provoke a response for some reason.

For the study mice had tumors implanted and the effect of a particular microbe (segmented filamentous bacteria, SFB) on it studied, with the presence of it markedly improving the response to anti-PD-1 treatment due to anti-gens expressed by SFB despite the large gut-skin distance. Whether in humans similar mechanisms play a similarly strong role remains to be investigated, but it offers renewed hope that cancer immunotherapies like CAR T-cell immunotherapy will one day make cancer an easily curable condition.

Bacteria Marching To The Beat Of A Tiny Drum

Traditionally, identifying a bacterium requires peering through a microscope. Researchers from TU Delft want to trade your eyes for your ears when identifying bacteria. This is possible because they’ve crafted nanoscale drums that convert bacteria’s movement into sound.

The technique originated when Delft researchers noticed something odd. If a living bacterium were on a graphene sheet, it would beat a distinctive pattern that you can detect with a laser. Each drumhead consists of two graphene sheets laid over an 8-micrometer-wide cavity. The sheets are less than a nanometer thick.

The sounds are due to the subtle motion of the tiny lifeform. Scientists have known about these motions, but previously had to measure them en masse. The tiny drums can respond to a single organism, typically about 1 to 10 micrometers in size.

Graphene makes this sensor possible because it is thin enough to behave like a drum with such a tiny force, yet also strong enough to support the bacterium. At first, the technique was simply to determine if antibiotics were killing the bacteria. However, they found that specific bacteria produced audio with unique spectrograms.

It is foolproof, but machine language models can identify among three common bacteria with nearly 90% accuracy. The next step is to reduce the high-tech research setup to something practical for a hospital or doctor’s office. Early prototypes are now in use in two hospitals.

We’ve seen the benefits of automated microscopes that can detect a particular disease. This technology, refined, could go even further.

Fighting Food Poisoning With A Patch

Food poisoning is never a fun experience. Sometimes, if you’re lucky, you’ll bite into something bad and realize soon enough to spit it out. Other times, you’ll only realize your mistake much later. Once the tainted food gets far enough into the digestive system, it’s too late. Your only option is to strap in for the ride as the body voids the toxins or pathogens by every means available, perhaps for several consecutive days.

Proper food storage and preparation are the key ways we avoid food poisoning today. However, a new development could give us a further tool in the fight—with scientists finding a way to actively hunt down and destroy angry little pathogens before they can spoil a good meal.

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Hackaday Links: May 18, 2025

Say what you want about the wisdom of keeping a 50-year-old space mission going, but the dozen or so people still tasked with keeping the Voyager mission running are some major studs. That’s our conclusion anyway, after reading about the latest heroics that revived a set of thrusters on Voyager 1 that had been offline for over twenty years. The engineering aspects of this feat are interesting enough, but we’re more interested in the social engineering aspects of this exploit, which The Register goes into a bit. First of all, even though both Voyagers are long past their best-by dates, they are our only interstellar assets, and likely will be for centuries to come, or perhaps forever. Sure, the rigors of space travel and the ravages of time have slowly chipped away at what these machines can so, but while they’re still operating, they’re irreplaceable assets.

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Where No E. Coli Has Gone Before

While we’re still waiting for ET to give us a ring, many worlds might not have life that’s discovered the joys of radio yet. Scientists ran a two-pronged study to see how bacteria might fare on other worlds.

We currently define the Habitable Zone (HZ) of a planet by the likelihood that particular planet can host liquid water due to its peculiar blend of atmosphere and distance from its star. While this doesn’t guarantee the presence of life, its a good first place to start. Trying to expand on this, the scientists used a climate model to refine the boundaries of the HZ for atmosphere’s dominated by H2 and COgases.

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Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Bacterium Demonstrates Extreme Radiation Resistance Courtesy Of An Antioxidant

Extremophile lifeforms on Earth are capable of rather astounding feats, with the secret behind the extreme radiation resistance of one of them now finally teased out by researchers. As one of the most impressive extremophiles, Deinococcus radiodurans is able to endure ionizing radiation levels thousands of times higher than what would decisively kill a multicellular organism like us humans. The trick is the antioxidant which this bacterium synthesizes from multiple metabolites that combine with manganese. An artificial version of this antioxidant has now been created that replicates the protective effect.

The ternary complex dubbed MDP consists of manganese ions, phosphate and a small peptide, which so far has seen application in creating vaccines for chlamydia. As noted in a 2023 study in Radiation Medicine and Protection by [Feng Liu] et al. however, the D. radiodurans bacterium has more survival mechanisms than just this antioxidant. Although much of the ionizing radiation is neutralized this way, it can not be fully prevented. This is where the highly effective DNA repair mechanism comes into play, along with a range of other adaptations.

The upshot of this is the synthesis of a very effective and useful antioxidant, but as alluded to in the press releases, just injecting humans with MDP will not instantly give them the same super powers as our D. radiodurans buddy.

Featured image: Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Life Found On Ryugu Asteroid Sample, But It Looks Very Familiar

Samples taken from the space-returned piece of asteroid Ryugu were collected and prepared under strict anti-contamination controls. Inside the cleanest of clean rooms, a tiny particle was collected from the returned sample with sterilized tools in a nitrogen atmosphere and stored in airtight containers before being embedded in an epoxy block for scanning electron microscopy.

It’s hard to imagine what more one could do, but despite all the precautions taken, the samples were rapidly colonized by terrestrial microorganisms. Only the upper few microns of the sample surface, but it happened. That’s what the images above show.

The surface of Ryugu from Rover 1B’s camera. Source: JAXA

Obtaining a sample from asteroid Ryugu was a triumph. Could this organic matter have come from the asteroid itself? In a word, no. Researchers have concluded the microorganisms are almost certainly terrestrial bacteria that contaminated the sample during collection, despite the precautions taken.

You can read the study to get all the details, but it seems that microorganisms — our world’s greatest colonizers — can circumvent contamination controls. No surprise, in a way. Every corner of our world is absolutely awash in microbial life. Opening samples on Earth comes with challenges.

As for off-Earth, robots may be doing the exploration but despite NASA assembling landers in clean room environments we may have already inadvertently exported terrestrial microbes to the Moon, and Mars. The search for life to which we are not related is one of science and humanity’s greatest quests, but it seems life found on a space-returned samples will end up looking awfully familiar until we step up our game.