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Ramesh Balwani, the former chief operating officer of the failed blood testing start-up, was convicted of 12 counts of fraud in July.Ramesh Balwani, the former chief operating officer of the failed blood testing start-up Theranos, was sentenced on Wednesday to nearly 13 years in prison for defrauding investors and patients about the company’s business and technology.Mr. Balwani, 58, and his convicted co-conspirator, Elizabeth Holmes, 38, the founder of Theranos, had promised that the start-up would revolutionize health care with machines and tests that could detect some illnesses using just a few drops of blood. But those claims were false, and Theranos became a tale of Silicon Valley’s ambition and hype run amok.Mr. Balwani, also known as Sunny, was convicted in July of 10 counts of wire fraud and two counts of conspiracy to commit wire fraud.Judge Edward J. Davila of U.S. District Court for the Northern District of California sentenced Mr. Balwani to 155 months, which is 12 years and 11 months, as well as three years of supervised release. Mr. Balwani must surrender to custody on March 15.His sentence was longer than that of Ms. Holmes, who was found guilty of four counts of fraud in January and sentenced last month to more than 11 years in prison. Mr. Balwani is expected to appeal. His lawyers asked that he be assigned to a minimum-security satellite camp in Lompoc, Calif.While wire fraud carries a maximum sentence of 20 years in prison, prosecutors had asked that Mr. Balwani be sentenced to 15 years and ordered to pay more than $800 million in restitution to investors. His lawyers had asked for just probation.As they did in Ms. Holmes’s case, prosecutors told Judge Davila that a long sentence would discourage Silicon Valley entrepreneurs and start-up founders from stretching the truth. In court filings, they also wrote that a long sentence would “rebuild the trust investors must have when funding innovators.”Elizabeth Holmes’s Epic Rise and FallThe Theranos founder’s story, from a $9 billion valuation to a fraud conviction, has come to symbolize the pitfalls of Silicon Valley’s culture.Con Artist: With Theranos, her blood-testing company, Elizabeth Holmes fooled investors, employees and media outlets. Then she got her comeuppance.The Start-up Playbook: Ms. Holmes wasn’t a creature of Silicon Valley, or so the refrain went. Her trial showed otherwise.Her Conviction: The Theranos founder was found guilty of four of 11 charges of fraud. She was sentenced to more than 11 years in prison.Her Co-conspirator: Ramesh Balwani, a former Theranos executive who helped Holmes cultivate her Steve Jobs-like image, was found guilty of 12 counts of fraud and sentenced to nearly 13 years in prison.Jeffrey Schenk, an assistant U.S. attorney and lead prosecutor, said in court on Wednesday that Mr. Balwani should receive a longer sentence than Ms. Holmes because he oversaw Theranos’s lab, which endangered patients.“Mr. Balwani had significant autonomy in running the lab. He made decisions that directly impacted the information that was communicated to patients,” Mr. Schenk said. The lab, he added, was the source of “some of the greatest harm.”Jeffrey Coopersmith, a lawyer for Mr. Balwani, blamed Ms. Holmes, who was not found guilty of defrauding patients. “She was the C.E.O. She was the face of Theranos,” he said.Mr. Balwani, who appeared in court with his family members, did not read a statement to the judge. No victims spoke.Michael Weinstein, a former federal prosecutor who leads white-collar litigation at the law firm Cole Schotz, said Mr. Balwani faced hurdles because he did not have “some of the same sympathies Ms. Holmes has.” He added that Mr. Balwani “being a little bit older and wiser” meant “the court would expect more from him as an executive.”Before Theranos, Mr. Balwani worked at software companies and helped lead an e-commerce start-up, where he earned a reported $40 million payout at the height of the dot-com boom. He and Ms. Holmes met when he was 37 and she was 18, and they started dating in secret shortly after Ms. Holmes started Theranos in 2003. Mr. Balwani joined the company and invested $4.6 million in it in 2009.After The Wall Street Journal exposed that Theranos’s tests did not work as advertised in 2015, Mr. Balwani left the company in 2016 and split with Ms. Holmes. Theranos shut down in 2018.That year, federal prosecutors charged Mr. Balwani and Ms. Holmes with fraud. Their cases were later separated, and Mr. Balwani went on trial this year.Prosecutors argued at the trial that he had known that Theranos’s technology did not work as promised because he was enmeshed in nearly every part of the business. Apart from leading the company’s lab, he created its financial projections and attended many meetings with investors.Mr. Balwani’s lawyers argued that he had been a true believer in Theranos and its mission. They said Ms. Holmes, not Mr. Balwani, had been in charge.Each defendant was frequently mentioned in the other’s trial, but they did not testify against each other. In her trial, Ms. Holmes accused Mr. Balwani of emotional and sexual abuse, which Mr. Balwani has denied and was not permitted as evidence in his trial.Ultimately, a jury found Mr. Balwani guilty of defrauding Theranos’s investors and patients. After the conviction, he asked for and was denied a new trial.Ms. Holmes, who is set to report to prison in April, signaled her plans to appeal her case in a filing this week. In it, she cited prosecutors’ differing presentations of her relationship with Mr. Balwani. The pair were presented as equals in her trial. But in Mr. Balwani’s trial, her lawyers wrote, “the government took the opposite position and highlighted Mr. Balwani’s age, experience and influence over Ms. Holmes.”Before imposing Mr. Balwani’s sentence, Judge Davila reflected on Mr. Balwani’s educational and business history, saying that the executive’s prior successes made his actions at Theranos “tragic.”“This was a successful business. The idea was strong,” Judge Davila said, referring to Theranos. But when problems at the company arose, he said, Mr. Balwani “chose to go forward with deception.”Erin Griffith

Their older parents need care. Their kids are still under 18. And they probably have a job, too.
They’re the “sandwich generation” — a longtime nickname for the mostly female, mostly middle-aged group of Americans who serve as caregivers for both older and younger family members at once.
A new study estimates there are at least 2.5 million of them, while giving a detailed view into who they are, and which older adults rely on them.
In all, nearly one quarter of adults who provide care for at least one parent over the age of 65 also take care of at least one child under 18, according to the new study from a team based in the University of Michigan Department of Psychiatry.
Writing in the Journal of the American Geriatrics Society, the researchers show how being in the middle of a caregiving sandwich differs from being a caregiver with an older adult, but no minor children, to care for.
Overall, sandwich generation caregivers were twice as likely to report financial difficulty (36% vs. 17%) and more likely to report substantial emotional difficulty (44% vs. 32%) than their peers who only act as caregiver to a parent over 65.

People who take cholesterol-lowering drugs called statins may have a lower risk of having a type of stroke called an intracerebral hemorrhage, according to a new study published in the December 7, 2022, online issue of Neurology®, the medical journal of the American Academy of Neurology. An intracerebral hemorrhage is caused by bleeding in the brain.
“While statins have been shown to reduce the risk of stroke from blood clots, there has been conflicting research on whether statin use increases or decreases the risk of a person having a first intracerebral hemorrhage,” said study author David Gaist, MD, PhD, of the University of Southern Denmark in Odense and a member of the American Academy of Neurology. “For our study, we looked at the lobe and non-lobe areas of the brain to see if location was a factor for statin use and the risk of a first intracerebral hemorrhage. We found that those who used a statin had a lower risk of this type of bleeding stroke in both areas of the brain. The risk was even lower with long-term statin use.”
The lobe area of the brain includes most of the cerebrum, including the frontal, parietal, temporal and occipital lobes. The non-lobe area primarily includes the basal ganglia, thalamus, cerebellum and brainstem.
For the study, researchers looked at health records in Denmark and identified 989 people with an average age of 76 who had an intracerebral hemorrhage in the lobe area of the brain. They were compared to 39,500 people who did not have this type of stroke and were similar in age, sex and other factors.
They also looked at 1,175 people with an average age of 75 who had an intracerebral hemorrhage in the non-lobe parts of the brain. They were compared to 46,755 people who did not have this type of stroke and were similar in age, sex and other factors.
Researchers used prescription data to determine information on statin use.
Of the total participants, 6.8% who had a stroke had been taking statins for five or more years, compared to 8.6% of those who did not have a stroke.
After adjusting for factors like high blood pressure, diabetes, and alcohol use, researchers found that people currently using statins had a 17% lower risk of having a stroke in the lobe areas of the brain and a 16% lower risk of stroke in the non-lobe areas of the brain.
Longer use of statins was associated with a lower risk of stroke in both areas of the brain. When using statins for more than five years, people had a 33% lower risk of having a stroke in the lobe area of the brain and a 38% lower risk of stroke in the non-lobe area of the brain.
“It’s reassuring news for people taking statins that these medications seem to reduce the risk of bleeding stroke as well as the risk of stroke from blood clots,” Gaist added. “However, our research was done in only the Danish population, which is primarily people of European ancestry. More research should be conducted in other populations.”
The study was supported by Novo Nordisk Foundation.
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As a species, humans are constantly interpreting signals to assess social situations and make predictions about what could happen next. Being able to tell if someone else, whether human or animal, is happy with us, about to get aggressive, or even paying attention, can have major evolutionary advantages.
Now, a new article in PLOS ONE led by the DogStudies research group at the Max Planck Institute of Geoanthropology, together with colleagues from Friedrich Schiller University of Jena, the Max Planck Institute for Human Development, Berlin and the University of Leipzig, reveals that while humans are better than chance at assessing interactions between humans, dogs, and monkeys, we struggle to predict aggressive behaviors in both dogs and humans.
To determine how good people are at assessing social situations, researchers showed 92 participants 27 video clips, each showing a non-verbal interaction between a pair of human children, a pair of dogs, or a pair of macaques. The participants were split into two groups, with one group categorizing the interactions as playful, neutral or aggressive, and the other predicting the outcome of each interaction.
Participants performed above chance level at categorizing interactions among all species and predicted accurate outcomes in 50-80% of interactions. However, the accuracy of categorizations and predictions depended on both the species and the social context of the interaction.
Intriguingly, and contrary to the experimenters’ hypotheses, participants were not better at assessing human interactions than those of other species. In addition, they performed especially poorly with aggressive interactions in dogs and in humans.
Given that identifying aggression in dogs and humans could help people avoid injury and even death, researchers expected participants to be best at assessing aggressive situations, but the current study reveals that such assessments are more difficult for people than anticipated.
“It is possible that we are biased to assume good intentions from other humans and from ‘man’s best friend’,” says Theresa Epperlein, first author of the new study. “Perhaps this bias prevents us from recognizing aggressive situations in these species.”
“Our results underscore the fact that social interactions can often be ambiguous,” adds senior author Juliane Bräuer, “and suggest that accurately predicting outcomes may be more advantageous than categorizing emotional contexts.”
While the current study reveals much about how well humans interpret social situations, it raises the question of how exactly we form our assessments and if our skills can improve with training — although previous research has shown that experience doesn’t always lead to better outcomes. To answer these questions, further studies are needed to determine which cues humans rely on while observing interactions, such as vocalizations, facial expressions, or body language, and how those cues are deployed by different species.
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In search of new biomarkers for nutrition and health studies, a research team from the Leibniz Institute for Food Systems Biology at the Technical University of Munich (LSB) has identified and structurally characterized three metabolites that could be considered as specific markers for individual coffee consumption. These are degradation products of a group of substances that are formed in large quantities during coffee roasting but are otherwise rarely found in other foods. This and the fact that the potential biomarkers can be detected in very small amounts of urine make them interesting for future human studies.
According to Statista, coffee is by far the most popular hot beverage in Germany. On average, around 168 liters are consumed per person per year. It is not only a stimulant, but also has positive health properties. For example, numerous observational studies indicate that moderate coffee consumption is associated with a reduced risk of type 2 diabetes or liver disease.
Biomarkers instead of self-reporting
However, with regard to the amounts of coffee drunk, such observational studies rely on participants’ self-reports, which are difficult to verify. “Complementary studies would therefore be desirable in which coffee consumption could be objectively verified using biomarkers in order to determine the health value of coffee even more reliably,” says Roman Lang, who heads the Biosystems Chemistry & Human Metabolism research group at LSB.
Although earlier studies had already pointed to biomarker candidates, research on this had stalled for years. The substances previously detected were metabolic intermediates or breakdown products (metabolites) of various coffee compounds whose urine concentrations correlated strongly with the level of coffee consumption. At the time, however, the researchers had not succeeded in clearly identifying the molecular structure of the metabolites.
Use of high-performance analytical technologies
Therefore, as part of a pilot study, Roman Lang’s team examined the urine samples of six people after they had consumed 400 ml of coffee three hours earlier. With the help of high-performance analytical technologies and self-produced reference substances, the team succeeded in identifying three candidate biomarkers in the urine and, for the first time, in clearly determining their chemical structure. These are a glucuronic acid conjugate of atractyligenin, whose glycosides are present in relatively high concentrations in coffee beverages, and two glucuronic acid derivatives of an atractyligenin oxidation product.
“Our findings help advance biomarker research,” says Roman Lang. Dose-response studies, pharmacokinetics and human studies with much larger numbers of subjects must now follow to test the biomarker suitability of the identified compounds, he adds. Veronika Somoza, director of the Freising-based Leibniz Institute adds, “Food-specific biomarkers are important tools to explore the health effects of food. Therefore, part of our scientific work at LSB is also focused on finding biomarkers for food consumption.”
Function of glucuronic acid conjugates
In human metabolism, glucuronic acid serves in particular the so-called “detoxification” of nonpolar substances. The latter include, for example, ingested drugs or plant substances, but also endogenous steroid hormones. The body converts the substances to glucuronides in the liver by binding them to glucuronic acid. These glucuronic acid conjugates are much more water-soluble than the original substances and can thus be easily excreted in the urine via the kidneys.

Besides the skin, the digestive tract is the tissue that is most exposed to environmental influences such as bacteria and viruses. Therefore, cells that form these barriers to the interior of the body also have special defence mechanisms. A research team led by Professor Dr Thorsten Hoppe has now shown that RNA interference, or RNAi for short, which is known to be a viral defence mechanism, also prevents the overproduction of the body’s own proteins in intestinal cells. The study ‘ER-Associated RNA Silencing Promotes ER Quality Control’ has been published in the journal Nature Cell Biology.
RNAi is able to recognize, bind, and ultimately degrade RNA from viruses. This prevents the production of viral proteins. With the help of green fluorescent proteins and further analyses in the nematode Caenorhabditis elegans, the UoC research team was able to show that RNAi also intervenes in cells during protein production to maintain the protein balance (protein homeostasis) of the intestinal cells. The body’s own protein production starts with the copying of DNA and the creation of the template molecule, also known as the messenger RNA (mRNA), in the cell nucleus. The mRNA is then taken to the endoplasmic reticulum (ER), where a protein is produced from the template molecule. As in a factory, the manufactured proteins are subject to a strict quality control. Deficient proteins are exported from the ER and degraded to avoid cellular waste and extensive negative consequences for the physiology and functionality of the cell as well as the tissue.
‘We observed that the RNAi mechanism specifically degrades messenger RNAs at the ER before the protein is even produced. This serves to protect the ER from being overloaded by too much production,’ said Dr Franziska Ottens, one of the first authors of the study. The scientists thus found a new mechanism to regulate protein production.
The interplay between RNAi and previously known ER quality control systems appears to be important for overall intestinal health. This is shown by the fact that simultaneous failure of both mechanisms impairs the important barrier function of the gut. The study results also suggest a link between ER functionality and quality control, which are important for protection against viral infection. For example, RNA viruses such as SARS-CoV use the ER for replication.
‘We were able to significantly suppress viral loads by specifically overstressing the ER. The interplay of protein homeostasis, RNAi, and viral infection could be an important approach for the prospective research and treatment of viral diseases,’ said doctoral candidate Sotirios Efstathiou, a member of Thorsten Hoppe’s team and another first author of the study.
The research was conducted at the CECAD Cluster of Excellence on Cellular Stress Responses in Aging-Associated Diseases at the University of Cologne. It was funded by the German Research Foundation (DFG) in the framework of the German Excellence Strategy and by the European Research Council. Furthermore, support from the Cologne Graduate School of Aging Research and the Alexander von Humboldt Foundation made the research possible.
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A newly discovered technique, reported in the journal Nanoscale, offers a low-cost way to enhance the effectiveness of existing drugs.
“If you take sand and heat it to 500 degrees Celsius, nothing changes,” said Bradley Smith, the Emil T. Hofman Professor of Science at the University of Notre Dame. So Smith, who is also the director of Notre Dame’s Integrated Imaging Facility, was puzzled when Canjia Zhai and Cassandra Shaffer, two doctoral students in the Department of Chemistry and Biochemistry who were working in his lab, discovered they had changed the structure of particles of silica — the main component of sand — at 80 degrees Celsius, a temperature similar to that of a cup of coffee.
The discovery happened by accident. The particles were microscopically small — a thousandth the diameter of a human hair. But like their larger counterparts marked “silica gel” in packages attached to new articles of clothing, these particles were porous and could retain a chemical. In this case, that chemical was a blue dye used to detect tumors in mice.
The new dye, which had been developed in Smith’s lab, was taking a long time to enter the narrow pores in the particles. So, to make the molecules move more quickly, Shaffer and Zhai warmed the mixture to just under boiling and left it overnight. When they returned the next day, they could see that the particles had turned blue.
To confirm that the dye had fully infused, Shaffer and Zhai enlisted the help of Tatyana Orlova and Maksym Zhukovskyi, microscopy experts at the Notre Dame Integrated Imaging Facility.
Orlova and Zhukovskyi produced high-resolution electron microscopy images that showed that not only had the dye infused, the silica particles themselves had changed shape. The original particles were solitary spheres lightly dotted with pores like the skin of an orange. The new structures were spherical and were composed of smaller dye-filled globules. They also had small openings here and there that revealed a hollow core inside. The overall unit resembled a hollow raspberry.

Cancer, caused by abnormal overgrowth of cells, is the second-leading cause of death in the world. Researchers from the Salk Institute have zeroed in on specific mechanisms that activate oncogenes, which are altered genes that can cause normal cells to become cancer cells.
Cancer can be caused by genetic mutations, yet the impact of specific types such as structural variants that break and rejoin DNA, can vary widely. The findings, published in Nature on December 7, 2022, show that the activity of those mutations depends on the distance between a particular gene and the sequences that regulate the gene, as well as on the level of activity of the regulatory sequences involved.
This work advances the ability to predict and interpret which genetic mutations found in cancer genomes are causing the disease.
“If we can better understand why a person has cancer, and what particular genetic mutations are driving it, we can better assess risk and pursue new treatments,” says Salk physician-scientist Jesse Dixon, senior author of the paper and an assistant professor in the Gene Expression Laboratory.
Most genetic mutations have no impact on a cancer and the molecular incidents that lead to oncogene activation are relatively rare. Dixon’s lab studies how genomes are organized in 3D space and seeks to understand why these changes happen in some, but not the majority, of circumstances. The team also wants to identify factors that might distinguish where and when these events occur.
“A gene is like a light and what regulates it are like the light switches,” says Dixon. “We are seeing that, because of structural variants in cancer genomes, there are a lot of switches that can potentially turn ‘on’ a particular gene.”
Using CRISPR-Cas9 gene editing, the research team introduced genetic mutations by cutting DNA in certain locations of the genome. They found that some of the variants they created had major impacts on the expression of nearby genes, and could ultimately cause cancer, but that most had essentially no impact. Some genes appeared to go haywire when they were brought into environments with novel regulatory sequences, and others were not affected at all. The type of sequence that was introduced appeared to have a huge impact on whether or not the cell became cancerous.
“Our next move is to test whether there are other factors in the genome that contribute to the activation of oncogenes,” says Zhichao Xu, a postdoctoral fellow at Salk and the paper’s co-first author. “We are also excited about a new CRISPR genome editing technology we are developing to make this type of genome engineering work much more efficient.”
Other authors on the study are Sahaana Chandran, Victoria T. Le, Rosalind Bump, Jean Yasis, Sofia Dallarda, Samantha Marcotte, Benjamin Clock, Nicholas Haghani, Chae Yun Cho, Selene Tyndale, Graham McVicker, and Geoffrey M. Wahl of Salk; Dong-Sung Lee of the University of Seoul, South Korea; and Kadir Akdemir and P. Andrew Futreal of the University of Texas MD Anderson Cancer Center.
The research was supported by the National Institutes of Health (DP5OD023071), the Leona M. and Harry B. Helmsley Charitable Trust (2017-PG-MED001), the National Institutes of Health National Cancer Institute (R35 CA197687), and the Breast Cancer Research Foundation.
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Autoimmune diseases are thought to be the result of mistaken identity. Immune cells on patrol, armed and ready to defend the body against invading pathogens, mistake normal human cells for infected cells and turn their weapons on their own healthy tissues. In most cases, though, finding the source of the confusion — the tiny fragment of normal human protein that looks dangerously similar to a protein from a pathogen — has been challenging for scientists. That missing piece of the puzzle has hampered efforts to develop effective diagnostics and specific therapies for many autoimmune conditions.
That finally may be changing. A team involving researchers from Washington University School of Medicine in St. Louis, Stanford University School of Medicine and Oxford University has developed a way to find crucial protein fragments that drive autoimmunity, as well as the immune cells that respond to them. The findings, published Dec. 7 in Nature, open a promising pathway to diagnose and treat autoimmune diseases.
“Of all genes, the HLA genes have the greatest amount of variation across the human population. There are many, many autoimmune diseases that are associated with specific variants of the HLA genes, and in most cases we don’t know why,” said co-senior author Wayne M. Yokoyama, MD, the Sam J. Levin and Audrey Loew Levin Professor of Arthritis Research at Washington University. “This paper outlines a strategy for figuring out why certain HLA variants are linked to certain diseases. It also provides strong evidence that cross-reactivity between human and microbial proteins drives autoimmunity in at least two diseases and probably many others. Now that we understand the underlying drivers, we can start focusing on the approaches that are most likely to yield benefits for patients.”
The autoimmune diseases ankylosing spondylitis, which involves arthritis in the spine and pelvis, and acute anterior uveitis, which is characterized by inflammation in the eye, are both strongly associated with an HLA variant called HLA-B*27. The link between ankylosing spondylitis and HLA-B*27 was discovered 50 years ago — making it one of the first such associations identified between disease and HLA variants — and it remains one of the strongest known associations between any disease and an HLA variant.
The HLA family of proteins is involved in helping immune cells detect invading pathogens and distinguishing between microbial and human proteins, and is highly variable across individuals. HLA proteins function like hands that pick up fragments of whichever proteins are lying about — microbial or human — and show them to immune cells called T cells to figure out if they’re a sign of danger (microbial) or not (human).
T cells don’t recognize protein fragments by themselves; they recognize the fragment plus the hand that holds it. Scientists have long assumed that the combination of this particular hand — HLA-B*27 — plus a bit of an unknown human protein was being misidentified as dangerous in people with either of the two diseases, triggering autoimmune attacks in the eye or the spine. But for decades, they couldn’t find the fragment. Some scientists began to speculate that the misidentification hypothesis was wrong and some other reason accounted for the association between HLA-B*27 and the two diseases.

Diarrhea is no longer the killer it was in the mid-20th century, when an estimated 4.5 million children under age 5 died of it every year. While lifesaving oral rehydration therapy turned the tide, it doesn’t prevent infection. Millions of children in low- and middle-income countries still endure repeated bouts of diarrhea that weaken their bodies and leave them vulnerable to malnutrition and stunted growth, and less able to fight off a wide range of infections.
Researchers at Washington University School of Medicine in St. Louis have determined, in studies of human cells as well as mice, how some types of diarrhea-causing Escherichia coli (E. coli) bacteria damage the intestines to cause malnutrition and stunting. And they’ve shown that vaccinating against a toxin produced by E. coli protects infant mice from intestinal damage.
The findings suggest that a vaccine against this kind of E. colicould boost global efforts to ensure that all children not only make it to age 5, but thrive. The study is available online in Nature Communications.
“Ideally, we’d like to have a vaccine that prevents acute diarrhea, which still kills half a million children a year, and that also protects against long-term effects such as malnutrition, which is perhaps the bigger part of the problem now,” said senior author James M. Fleckenstein, MD, a professor of medicine and of molecular microbiology. “When kids become malnourished, their risk of dying from any cause goes up. The World Health Organization is in the process of deciding how to prioritize vaccines for kids in low- and middle-income countries, and I think these data suggest that vaccinating kids against E. coli diarrhea could be hugely beneficial in places that struggle with this.”
Fleckenstein studies a kind of E. coli known as enterotoxigenic E. coli, or ETEC — so named for the two toxins it produces — and its effects on children who live where the bacteria run rampant. E. coli is a common cause of diarrhea worldwide, but the strains found in the U.S. and other high-income countries typically don’t carry the same toxins as those in low- and middle-income countries. And that may make all the difference.
A 2020 study by Fleckenstein and Alaullah Sheikh, PhD — then a postdoctoral researcher in Fleckenstein’s lab and now an instructor in medicine — indicated that one of ETEC’s two toxins, heat-labile toxin, does more than trigger a case of the runs. The toxin also affects gene expression in the gut, ramping up genes that help the bacteria stick to the gut wall.
As part of the latest study, Fleckenstein and Sheikh discovered that the toxin suppresses a whole suite of genes related to the lining of the intestines, where nutrients are absorbed. The so-called brush border of the intestine is composed of microscopic, finger-like projections called microvilli that are tightly packed over the surface of the intestines like bristles on a brush. When Fleckenstein and Sheikh applied the toxin to clusters of human intestinal cells, the brush border disintegrated.
“Instead of being nice and tight and upright with thousands of microvilli per cell, they are short, floppy and sparse, kind of like if you had plucked out most of the bristles, and what was left was kind of raggedy,” said Sheikh, who led the 2020 and current studies. “That alone would have a negative impact on the body’s ability to absorb nutrients. But on top of that, we found that genes related to absorbing specific vitamins and minerals — notably vitamin B1 and zinc — also were downregulated. That could explain some of the micronutrient deficiencies we see in children repeatedly exposed to these bacteria.”
Children in low- and middle-income countries tend to get diarrhea over and over, and the risk of malnutrition and stunting goes up with each bout. Studying infant mice, the researchers found that a single infection with toxin-producing E. coli was sufficient to damage the brush border, while repeated infections led to extensive intestinal damage and growth lag. Pups infected with a strain of E. coli that lacks the toxin showed no such intestinal damage or stunting.
If the toxin is the problem, an immune response neutralizing the toxin may prevent the long-term effects, Fleckenstein and Sheikh reasoned. To find out, they vaccinated nursing mouse mothers with the toxin. Suckling mice are too young to be immunized themselves, but their vaccinated mothers produce antibodies that pass to the pups through breast milk. The researchers found that the intestines of infant mice from vaccinated mothers appeared healthy, suggesting that vaccination can protect against the intestinal damage leading to malnutrition.
“This is an argument for developing a vaccine for this kind of E. coli,” Fleckenstein said. “There are lifelong consequences of getting infected over and over in childhood. Vaccination combined with efforts to improve sanitation and access to clean water could protect children from the long-term effects and give them a better shot at long and healthy lives.”