Scientists at the University of Wisconsin–Madison have uncovered a possible way to protect key cells in the pancreas that are targeted during the development of Type 1 diabetes.

The researchers found that deleting a single stress-response gene in insulin-producing cells protects mice that are genetically predisposed to Type 1 diabetes from developing the disease. The findings suggest a new path to reduce stress inside those cells and alter how the immune system responds, potentially opening new avenues for early intervention or prevention.

Type 1 diabetes occurs when immune cells destroy pancreatic beta cells, leaving the body unable to produce enough insulin to regulate blood sugar. To date, most treatments have focused on suppressing immune activity.

“Historically, because it’s an autoimmune disease, scientists and clinicians have focused on preventing the immune attack,” says Feyza Engin, a professor in the UW–Madison Department of Biomolecular Chemistry who led the research, which was recently published in Nature Communications. “We looked at it from another angle and asked: Why are beta cells specifically targeted?”

The new research centers on a protein called XBP1. It’s part of a cellular stress response system that helps cells cope with inflammation, environmental toxins and the buildup of misfolded proteins. Earlier work from Engin’s lab showed that deleting a related stress sensor, Ire1α, in beta cells also prevented diabetes in mice. The new study builds on that foundation.

Using a mouse model that spontaneously develops Type 1 diabetes, Engin and her colleagues deleted the Xbp1 gene specifically in beta cells before immune assault. Although the mice initially showed elevated blood glucose, they later returned to normal glucose levels and remained healthy for as long as a year.

“What was really interesting is that early on they show hyperglycemia, but then they recover from it,” Engin says. “They actually go from diabetes back to normal blood glucose levels.”

An analysis revealed that beta cells lacking the Xbp1 gene temporarily lost features that mark them as mature insulin-producing cells. During this phase, immune cells were less likely to recognize and attack them. Over time, the beta cells regained their identity, inflammation decreased and insulin production recovered.

“They’re losing their beta cell identity and look nothing like a typical beta cell,” Engin says. “That’s why immune cells don’t recognize them.”

Importantly, the protective effect occurred without any changes to another stress-related process involving Ire1α, helping to clarify how different components of cells’ stress response influence the disease.

To better understand those differences, the team compared beta cells lacking Xbp1 with those missing Ire1α under identical environmental conditions — an important part of Type 1 diabetes research, where environmental conditions like housing and diet can affect disease rates in mice. Using single-cell sequencing from these mouse models and gene regulatory network analysis performed by UW–Madison collaborator Sushmita Roy’s lab, the team identified both shared stress pathways and ones involving only Xbp1.

“We found unique gene regulatory networks specific to Xbp1 that was never discovered before,” Roy says.

The findings add to evidence that beta cells play an active role in Type 1 diabetes rather than serving as passive targets.

“Our findings further support that beta cells are actually not victims,” Engin says. “They actively participate in their own destruction.”

While the study was conducted in mice, Engin says the work is designed with human disease in mind. People at high risk for Type 1 diabetes can often be identified years before symptoms appear through blood tests.

“If you identify these people who will develop diabetes at that stage, can we interfere?” she said. “Can we inhibit XBP1 and prevent or delay their diabetes?”

The lab is now actively pursuing those questions in further studies, Engin says, both in mice and in lab-grown human pancreatic cells.

This research was supported by the National Institutes of Health (T32 GM007215; DK130919; DK128136; 3-SRA-2023-1315-S-B; 3-SRA-2025-1654-S-B; and R01 GM144708), Greater Milwaukee Foundation and the University of Wisconsin Stem Cell and Regenerative Medicine Center.

Research at the University of Wisconsin–Madison drives innovation, saves lives, creates jobs, supports small businesses, and fuels the industries that keep America competitive and secure. It makes the U.S.—and Wisconsin—stronger. Federal funding for research is a high-return investment that’s worth fighting for.

Learn more about the impact of UW–Madison’s federally funded research and how you can help.

Quanyin Hu poses in his lab.

Using a newly discovered byproduct of dying cancer cells, University of Wisconsin–Madison researchers are developing personalized vaccines that could help keep aggressive tumors from recurring.

Led by Quanyin Hu, a professor in the UW–Madison School of Pharmacy, the research team has already found success slowing the recurrence of tumors in mouse models of triple negative breast cancer and melanoma. Currently, the long-term prognosis for human patients with these cancers is relatively poor. That’s in part because the diseases have a tendency to recur after the initial treatments to remove the tumors.

The personalized vaccine approach is an extension of the team’s recent discovery of pyroptotic vesicles, which are tiny sacs filled with the remnants of cancer cells when they undergo programmed cell death.

Crucially, the remnants in these microscopic sacs include antigens specific to the tumor, along with other molecular bits that can help direct immune cells to find and suppress cancer cells that might remain after a tumor is surgically removed.

In their study, recently published in the journal Nature Nanotechnology, Hu and his colleagues engineered these sacs to carry an immune stimulating drug. They then embedded these engineered vesicles into a hydrogel that can be implanted into the space left behind after surgical removal of a tumor.

This image shows the formation of pyroptotic vesicles, which look like small bubbles, in cancer cells as they undergo programmed cell death. A team of researchers led by UW–Madison pharmacy professor Quanyin Hu have developed a method for harnessing these vesicles to deliver vaccines against tumors with a high rate of recurrence. Image courtesy of Quanyin Hu

Using a melanoma mouse model and two different types of mouse models for triple negative breast cancers, including one with a human-derived tumor, the researchers compared their new approach with other cancer vaccine methods being studied. The mice that received the hydrogel laden with their engineered sacs survived significantly longer than others.

“Compared to the other approaches, ours shows a much stronger immune response,” says Hu. “We were one of the first groups to identify these pyrotopic vesicles and the first to show their effectiveness in helping prevent cancer recurrence, and we are very excited about their potential.”

Hu says the approach could theoretically apply to any cancer that tends to recur, such as pancreatic cancer and glioblastoma, the most common and extremely aggressive brain tumor. This potential is because the engineered sacs contain molecular information that is unique to an individual’s cancer cells, meaning the immune response they create is uniquely positioned to attack those cells.

Another advantage of this approach is the localized nature of the treatment. Most cancer vaccines under development carry the risk for severe side effects because of how they’re given — through systemic injections. Hu says that applying the engineered vesicles directly to the site of the removed tumor greatly reduces the risk of systemic side effects.

While the approach will require more testing in mice and other animal models before it can be tested in humans, Hu is bullish about its potential. Several of the mice that received the highest doses of the experimental treatment remained cancer free throughout the course of the study.

“That’s really exciting because we demonstrated that we could essentially cure these mice with no tumor recurrence,” Hu says.

This research was supported in part by the National Institutes of Health (R01EB035992 and R01CA288851), the American Cancer Society (RSG-23-1140821-01-ET) and the METAVIVOR Foundation.

Research at the University of Wisconsin–Madison drives innovation, saves lives, creates jobs, supports small businesses, and fuels the industries that keep America competitive and secure. It makes the U.S. — and Wisconsin — stronger. Federal funding for research is a high-return investment that’s worth fighting for. Learn more about the impact of UW–Madison’s federally funded research and how you can help protect it.

If the drug proves viable to treat epilepsy in humans, it would be the first to provide lasting relief from seizures even after patients stopped taking it. iStock/cagkansayin

A drug typically prescribed for arthritis halts brain-damaging seizures in mice that have a condition like epilepsy, according to researchers at the University of Wisconsin–Madison.

The drug, called tofacitinib, also restores short-term and working memory lost to epilepsy in the mice and reduces inflammation in the brain caused by the disease. If the drug proves viable for human patients, it would be the first to provide lasting relief from seizures even after they stopped taking it.

“It ticks all the boxes of everything we’ve been looking for,” says Avtar Roopra, a neuroscience professor in the UW–Madison School of Medicine and Public Health and senior author of the study, which was published last week in the journal Science Translational Medicine.

Epilepsy is one of the most common neurological diseases, afflicting more than 50 million people around the world. While there are many known causes, the disease often appears after an injury to the brain, like a physical impact or a stroke.

Some days, months or even years after the injury, the brain loses the ability to calm its own activity. Normally balanced electrical activity through the brain goes haywire.

“The system revs up until all the neurons are firing all the time, synchronously,” says Roopra. “That’s a seizure that can cause massive cell death.”

And the seizures repeat, often at random intervals, forever. Some drugs have been useful in addressing seizure symptoms, protecting patients from some of the rampant inflammation and memory loss, but one-third of epilepsy patients do not respond to any known drugs, according to Olivia Hoffman, lead author of the study and a postdoctoral researcher in Roopra’s lab. The only way to stop the most damaging seizures has been to remove a piece of the brain where disruptive activity starts.

On their way to identifying tofacitinib’s potential in epilepsy, Hoffman and co-authors used relatively new data science methods to sift through the way thousands of genes were expressed in millions of cells in the brains of mice with and without epilepsy. They found a protein called STAT3, key to a cell signaling pathway called JAK, at the center of activity in the seizure-affected mouse brains.

“When we did a similar analysis of data from brain tissue removed from humans with epilepsy, we found that was also driven by STAT3,” Hoffman says.

“[The discovery] ticks all the boxes of everything we’ve been looking for,” says Avtar Roopra (right), seated with research collaborator Olivia Hoffman.

Meanwhile, Hoffman had unearthed a study of tens of thousands of arthritis patients in Taiwan aimed at describing other diseases associated with arthritis. It turns out, epilepsy was much more common among those arthritis patients than people without arthritis — but surprisingly less common than normal for the arthritis patients who had been taking anti-inflammatory drugs for more than five-and-a-half years.

“If you’ve had rheumatoid arthritis for that long, your doctor has probably put you on what’s called a JAK-inhibitor, a drug that’s targeting this signaling pathway we’re thinking is really important in epilepsy,” Hoffman says.

The UW researchers ran a trial with their mice, dosing them with the JAK-inhibitor tofacitinib following the administration of a brain-damaging drug that puts them on the road to repeated seizures. Nothing happened. The mice still developed epilepsy like human patients.

Remember, though, that epilepsy doesn’t often present right after a brain-damaging event. It can take years. In the lab mice, there’s usually a lull of weeks of relatively normal time between the brain damage and what the researchers call “reignition” of seizures. If it’s not really epilepsy until reignition, what if they tried the drug then? They devised a 10-day course of tofacitinib to start when the mouse brains fell out of their lull and back into the chaos of seizures.

“Honestly, I didn’t think it was going to work,” Hoffman says. “But we believe that initial event sort of primes this pathway in the brain for trouble. And when we stepped in at that reignition point, the animals responded.”

The drug worked better than they could have imagined. After treatment, the mice stayed seizure-free for two months, according to the paper. Collaborators at Tufts University and Emory University tried the drug with their own mouse models of slightly different versions of epilepsy and got the same, seizure-free results.

Roopra’s lab has since followed mice that were seizure-free for four and five months. And their working memory returned.

“These animals are having many seizures a day. They cannot navigate mazes. Behaviorally, they are bereft. They can’t behave like normal mice, just like humans who have chronic epilepsy have deficits in learning and memory and problems with everyday tasks,” Roopra says. “We gave them that drug, and the seizures disappear. But their cognition also comes back online, which is astounding. The drug appears to be working on multiple brain systems simultaneously to bring everything under control, as compared to other drugs, which only try to force one component back into control.”

Because tofacitinib is already FDA-approved as safe for human use for arthritis, the path from animal studies to human trials may be shorter than it would be for a brand-new drug. Roopra’s epilepsy research has long been funded by the National Institutes of Health as well as key early support from Madison-based Lily’s Fund for Epilepsy Research and CURE Epilepsy.

The next steps toward human patients largely await NIH review of new studies, which have been paused indefinitely amid changes at the agency.

For now, the researchers are focused on trying to identify which types of brain cells are shifted back to healthy behavior by tofacitinib and on animal studies of even more of the many types of epilepsy. Hoffman and Roopra have also filed for a patent on the use of the drug in epilepsy.

This research was funded in part by grants from the National Institutes of Health (R01NS108756, R21NS093364, R01NS112308, NS112350, R01NS105628, R01NS102937 and R21NS120868).

Heart muscle cells grown from human induced pluripotent stem cells (in green) have successfully integrated into rhesus macaque heart muscle in this microscope image of heart tissue from a new study by UW–Madison and Mayo Clinic researchers. Photo courtesy Emborg Lab / UW–Madison

Heart muscle cells grown from stem cells show promise in monkeys with a heart problem that typically results from a heart defect sometimes present at birth in humans, according to new research from the University of Wisconsin–Madison and Mayo Clinic.

Heart disease, the No. 1 killer of Americans, can affect people at any time across their lifespans — even from birth, when heart conditions are known as congenital heart defects. Regenerating tissue to support healthy heart function could keep many of those hearts beating stronger and longer, and this is where stem cell research is stepping in.

A research team led by Marina Emborg, professor of medical physics in the UW–Madison School of Medicine and Public Health, and Timothy Nelson, physician scientist at the Mayo Clinic in Rochester, Minnesota, reported recently in the journal Cell Transplantation that heart muscle cells grown from induced pluripotent stem cells can integrate into the hearts of monkeys with a state of pressure overload.

Also referred to as right ventricular dysfunction, pressure overload often affects children with congenital heart defects. Patients experience chest discomfort, breathlessness, palpitations and body swelling, and can develop a weakened heart. The condition can be fatal if left untreated.

Nearly all single ventricle congenital heart defects, particularly those in the right ventricle, eventually lead to heart failure. Surgery to correct the defect is a temporary solution, according to the researchers. Eventually, patients may require a heart transplant. However, the availability of donor hearts — complicated by the young age at which most patients require a transplant — is extremely limited.

In their new study, the researchers focused on grafts of stem cell-derived cardiomyocytes as a possible complementary treatment to traditional surgical repair of cardiac defects. Their goal was to directly support ventricular function and overall healing.

“There is a great need for alternative treatments of this condition,” says Jodi Scholz, the study’s lead author and chair of Comparative Medicine at Mayo Clinic. “Stem cell treatments could someday delay or even prevent the need for heart transplants.”

The researchers transplanted clinical-grade human induced pluripotent stem cells — cells collected from human donors, coaxed back into a stem cell state and then developed into cell types compatible with heart muscle — into rhesus macaque monkeys with surgically induced right ventricular pressure overload. The cells successfully integrated into the organization of the surrounding host myocardium, the muscular layer of the heart. The animals’ hearts and overall health were closely monitored throughout the process. The authors noted that episodes of ventricular tachycardia (an increased heart rate) occurred in five out of 16 animals receiving transplanted cells, with two monkeys presenting incessant tachycardia. These episodes resolved within 19 days.

“We delivered the cells to support existing cardiac tissue,” Emborg says. “Our goal with this particular study, as a precursor to human studies, was to make sure that the transplanted cells were safe and would successfully integrate with the organization of the surrounding tissue. We leveraged my team’s experience with stem cells and cardiac evaluation in Parkinson’s disease to assess this innovative therapeutic approach.”

The research proved the feasibility and safety of using stem cells in the first nonhuman primate model of right ventricular pressure overload. Macaques, in particular, have been critical to advancing stem cell therapies for heart disease, kidney disease, Parkinson’s disease, eye diseases and more.

“The demonstration of successful integration and maturation of the cells into a compromised heart is a promising step towards the clinical application for congenital heart defects,” Emborg says.

The research was supported by the Todd and Karen Wanek Family Program for Hypoplastic Left Heart Syndrome and National Institutes of Health Grant P51OD011106 to the Wisconsin National Primate Research Center.

Ting Fu

Inflammation in the gut can trigger a doom loop of sorts. The condition messes with the sensitive relationships between food, digestive acids, microbes and the immune system in ways that can promote further inflammation and, sometimes, the eventual growth of tumors.

Scientists at the University of Wisconsin–Madison have identified a promising new target for treatments that could help the millions of people worldwide who suffer from inflammatory bowel disease and related colorectal cancers.

An essential regulator of gut health

Under the guidance of Ting Fu, an assistant professor in the UW–Madison School of Pharmacy, researchers uncovered a previously unknown function of a protein that is central to gut health and implicated in the development of colitis, a severe and chronic form of IBD. A debilitating condition in and of itself, colitis is also linked to an increased risk for colorectal cancer. The team’s findings suggest that the protein is a promising target for future colitis treatments.

The protein is called the farnesoid X receptor, or FXR. It helps control the production of bile acids that digest fats. Working in tandem, FXR and bile acids play several critical roles in maintaining a healthy gut. Together, they help balance gut bacteria, promote a healthy intestinal lining, and influence immune cells called macrophages that patrol the digestive system and ward off pathogens that sneak in with the food we eat.

“This balance can be thrown off when FXR isn’t functioning properly,” says Xingchen Dong, a postdoctoral researcher in Fu’s lab and the study’s lead author.

Dong, Fu and their colleagues studied mice with chronic gastrointestinal inflammation that led to the growth of tumors in their colons. This mimicked the effects of colitis-associated colon cancer in humans. They found that FXR was not functioning properly in these mice, messing with the signals the protein sends to manage bile acids.

At the same time, they noted shifts in the chemistry of bile acids within the animals’ gastrointestinal tracts. These changes affected both “host” bile acids, produced by the mice themselves, and microbial bile acids, which are the product of gut microbes metabolizing host bile acids.

In a cascade of negative effects, the altered bile acids prompted changes in the behavior of gut macrophages, leading to a large increase in certain proteins called cytokines that promote inflammation. This observation provided compelling new evidence for how FXR dysfunction changes the behavior of gut macrophages, initiating the inflammation doom loop that can cause colitis and eventually lead to aggressive cancers.

From a scientific perspective, “it is exciting to see that gut macrophages have the capability to sense both host and microbial bile acids and exhibit diverse responses to various bile acids, which leads to changes in their state or activity,” says Fu.

This image shows the effect of pro-inflammatory cytokines on the growth of a mouse intestinal organoid. Intestinal stem cells (red) are indicative of inflammation and Ki67 proteins (green) are associated with tumors. Photo courtesy of Ting Fu

A promising treatment for colitis and associated cancers

FXR dysfunction is implicated in a number of gastrointestinal diseases, and Fu’s team investigated whether existing drugs aimed at activating FXR — called FXR agonists — might prove effective treatments for colitis and associated colon cancers.

Mice treated with either of two FXR agonists — fexaramine D or FDA-approved obeticholic acid — saw marked improvement in FXR functioning, with a stream of other positive effects, including rebalanced bile acids, improved macrophage function and reduced intestinal inflammation.

Colorectal tumors in the treated mice were also “profoundly reduced” in both number and size, according to Fu. The median survival time of mice with colitis-associated cancer was twice as long in animals treated with the compounds compared to those that received no treatment. The findings were published Jan. 23 in the journal JCI Insight.

“This study shows that FXR plays a crucial role in regulating how macrophages behave in the gut,” says Fu. “This could be really important for developing new treatments for IBD and colitis-associated cancers.”

Fu intends to continue exploring compounds that promote FXR function as potential treatments for colitis and related cancers, though any treatment strategies for human patients based on this research will require further exploration and confirmation.

This work was funded by UW–Madison startup grants (AAI3795, AAI3894), UW Carbone Cancer Center startup support (AAI5122), UW Center for Human Genomics & Precision Medicine startup support (AAI5319), fall competition support from Wisconsin Alumni Research Foundation (AAL8735), as well as American Cancer Society institutional grant (AAH4826), and American Cancer Society – Coaches vs. Cancer – Bo Ryan-Jay Holliday Families FundResearch Scholar Grants (RSG-23-1150338-01) and the Margaret Q. Landenberger Research Foundation.

“We like to say a calorie is not just a calorie,” says Dudley Lamming, a professor and metabolism researcher at the University of Wisconsin School of Medicine and Public Health. “Different components of your diet have value and impact beyond their function as a calorie, and we’ve been digging in on one component that many people may be eating too much of.”

Lamming is the lead author of a new study in mice, published recently in the journal Cell Metabolism, showing that cutting down the amount of a single amino acid called isoleucine can, among other benefits, extend their lifespan, make them leaner and less frail as they age and reduce cancer and prostate problems, all while the mice ate more calories.

Amino acids are the molecular building blocks of proteins, and Lamming and his colleagues are interested in their connection to healthy aging.

In earlier research, data from UW–Madison’s Survey of the Health of Wisconsin showed the scientists that Wisconsinites with higher body mass index measurements (higher is more overweight or obese) tend to consume more isoleucine, an essential amino acid everyone needs to eat. Isoleucine is plentiful in foods including eggs, dairy, soy protein and many kinds of meat.

To better understand its health effects, Lamming and collaborators from across disciplines at UW–Madison fed genetically diverse mice either a balanced control diet, a version of the balanced diet that was low in a group of about 20 amino acids, or a diet formulated to cut out two-thirds of the diet’s isoleucine. The mice, which began the study at about 6 months of age (equivalent to a 30-year-old person) got to eat as much as they wanted.

“Very quickly, we saw the mice on the reduced isoleucine diet lose adiposity — their bodies got leaner, they lost fat,” says Lamming, while the bodies of the mice on the low-amino-acid diet also got leaner to start, but eventually regained weight and fat.

Mice on the low-isoleucine diet lived longer — on average 33% longer for males and 7% longer for females. And, based on 26 measures of health, including assessments ranging from muscle strength and endurance to tail use and even hair loss, the low-isoleucine mice were in much better shape during their extended lives.

“Previous research has shown lifespan increase with low-calorie and low-protein or low-amino-acid diets starting in very young mice,” says Lamming, whose work is supported by the National Institutes of Health. “We started with mice that were already getting older. It’s interesting and encouraging to think a dietary change could still make such a big difference in lifespan and what we call ‘healthspan,’ even when it started closer to mid-life.”

The mice on the low-isoleucine diets chowed down, eating significantly more calories than their study counterparts — probably to try to make up for getting less isoleucine, according to Lamming. But they also burned far more calories, losing and then maintaining leaner body weights simply through adjustments in metabolism, not by getting more exercise.

At the same time, Lamming says, they maintained steadier blood sugar levels and male mice experienced less age-related prostate enlargement. And while cancer is the leading cause of death for the diverse strain of mice in the study, the low-isoleucine males were less likely to develop a tumor.

Dietary amino acids are linked to a gene called mTOR that appears to be a lever on the aging process in mice and other animals as well as to a hormone that manages the body’s response to cold and has been considered a potential diabetes drug candidate for human patients. But the mechanism behind the stark benefits of low-isoleucine intake is not well understood. Lamming thinks the new study’s results may help future research pick apart causes.

“That we see less benefit for female mice than male mice is something we may be able to use to get to that mechanism,” he says.

While the results are promising, humans do need isoleucine to live. And winnowing a significant amount of isoleucine out of a diet that hasn’t been preformulated by a mouse chow company is not an easy task.

“We can’t just switch everyone to a low-isoleucine diet,” Lamming says. “But narrowing these benefits down to a single amino acid gets us closer to understanding the biological processes and maybe potential interventions for humans, like an isoleucine-blocking drug.”

The Survey of the Health of Wisconsin showed that people vary in isoleucine intake, with leaner participants tending to eat a diet lower in isoleucine. Other data from Lamming’s lab suggest that overweight and obese Americans may be eating significantly more isoleucine than they need.

“It could be that by choosing healthier foods and healthier eating in general, we might be able to lower isoleucine enough to make a difference,” Lamming says.

This research was funded in part by grants from the National Institutes of Health (AG056771, AG062328, AG081482, AG084156, DK125859, F31AG066311, R01AG062328-03S1, F31AG081115, F31AG082504, T32AG000213, F32AG077916, RF1AG056771-06S1, K01AG059899, R01DK133479, P30DK020579, K12HD101368, R01AA029124, P30 CA014520, P50DE026787, U54DK104310, R01DK131175 and P30CA014520) and the U.S. Department of Veterans Affairs (I01-BX004031).

The study also found that changes discovered in the modified mouse beta cells are also present in human beta cells that manage to survive the widespread beta-cell death that characterizes Type 1 diabetes.

This gives the researchers hope that their findings, published today in the journal Cell Metabolism, may point to a potential new treatment that could be administered very early in the development of diabetes. Type 1 diabetes afflicts as many as 20 million people around the world, contributing to glaucoma, nerve damage, high blood pressure and stroke. In the United States, it shortens life expectancy by more than a decade.

Feyza Engin

“When we eat, our beta cells produce about 1 million molecules of insulin every minute to help maintain normal blood glucose levels,” says Feyza Engin, a UW–Madison professor of biomolecular chemistry and senior author of the new study. “That is a big and stressful job, especially for a part of these beta cells called the endoplasmic reticulum.”

The endoplasmic reticulum is like the cell’s warehouse staff. It folds the insulin protein molecules that a beta cell produces, packing them for shipping to other parts of the body. If something goes wrong with the protein folding process, the shipping process backs up or even stops, stressing the endoplasmic reticulum. A stress-response gene called Atf6 perks up when a cell is struggling with unfolded proteins. But if Atf6 can’t resolve the protein-folding problem, prolonged stress will eventually kill the cell.

Engin’s lab bred a line of diabetes-predisposed mice without the Atf6 gene in their beta cells. Instead of meeting their typical fate, those mice were protected from diabetes. Analysis of the genes expressed by their beta cells suggested the cells entered a state called senescence far ahead of schedule.

Senescence is a period of the cell’s life cycle in which it stops dividing and halts other normal cellular business. Senescing cells can cause problems for neighboring cells by releasing inflammatory messaging molecules that trigger an immune system response.

“We removed — knocked-out — the Atf6 gene in the beta cells in the pancreas of our mouse model of Type 1 diabetes, and they did not become diabetic,” Engin says. “Instead of dying off, these cells unexpectedly appear to go into an early senescence state that initiated a beneficial immune response and helped the cells survive an autoimmune attack.”

DNA damage, stress and aging can kick off senescence, which can draw an immune system response that cleans up the senescent cells. If the immune system fails to clear these cells, they accumulate and cause chronic inflammation and disease.

“The beta cells without Atf6 exhibit transient senescence and start releasing this group of proteins, including leukemia inhibitory factor, or LIF, that recruits protective immune cells called M2 macrophages,” Engin says.

Macrophages are white blood cells that eat things — pathogens, foreign bodies, dead cells — that don’t belong in the body. In the pancreases of the Atf6-knockout mice, the M2 macrophages appeared to work around the altered beta cells, relieving inflammation and helping to reduce the accumulation of other, detrimental senescent cells. This led to healthier tissue and improved beta cell health and function, staving off Type 1 diabetes.

Even more exciting, Engin says, is how closely the new study’s results in mice appear to be reflected in human cells.

With a blood test, doctors can identify people who are at high-risk of developing Type 1 diabetes months in advance of the death of their beta cells.

“That may be a perfect timeframe for a treatment based on pharmacological inhibition of Atf6 or induction of LIF and other secreted proteins,” says Engin, whose work is funded by the National Institutes of Health. “If we can get there in time to protect these cells with transient senescence, the onset of diabetes might be prevented.”

While nearly all beta cells die off in diabetes, a few — though too few to be effective insulin suppliers — do survive. To see whether their mouse findings could be applicable in humans, Engin’s lab, with collaborators at Case Western Reserve University, Université Libre de Bruxelle and the University of Manitoba, studied beta cell samples taken from diabetes patients.

“In those surviving beta cells, we found reduced Atf6 activity and an early senescence gene expression pattern, suggesting this same process that kept our mice from becoming diabetic may have worked to protect these residual beta cells in humans,” Engin says.

The researchers hope to build on those findings by delving further into the role and potential benefits of senescence in Type 1 diabetes and other diseases.

This research was supported by grants from the National Institutes of Health (T32 GM007215, DK053307, DK060596, U01 DK127786, DK126444, DK133881-01, DK130919, DK128136), Juvenile Diabetes Research Foundation, Children’s Hospital Research Institute of Manitoba, Canadian Institutes of Health Research, Belgium’s Fund for Scientific Research, Dutch Diabetes Research Foundation and the Greater Milwaukee Foundation.

This schematic shows a two-step drug delivery approach to treating cancer tumors developed by UW–Madison researchers. On the left, engineered proteins (shown as red) initiate clotting at the site of a tumor before nanoparticles coated with a blood platelet membrane and loaded with an anti-cancer drug are injected and attracted to the clots within the tumor. Image by Quanyin Hu

University of Wisconsin–Madison researchers have developed a new method for targeting tumors with cancer drugs by exploiting the clotting propensity of blood platelets.

The new approach, first described March 29 in the journal Science Advances, adds to a growing set of innovative drug delivery techniques under development in the lab of Quanyin Hu, a professor in the UW–Madison School of Pharmacy.

One of Hu’s research goals is to improve the effectiveness and safety of cancer immunotherapies. Such treatments have shown promise by bolstering the ability of the immune system to combat cancer cells, but they come with their own set of challenges. One significant obstacle is that the drugs can target normal cells in addition to tumors. This can make the treatments less effective and sometimes lead to serious side effects.

Quanyin Hu

To better target the therapeutics at tumors, Hu and his colleagues considered a mechanism that results in a very specific biological chain reaction — the cellular signals that trigger blood to clot.

“This whole study is purely inspired by nature and the natural features of platelets to participate in clot formation,” says Hu.

First, the researchers used an engineered protein designed to locate and bind to tumor blood vessels and then initiate thrombosis, or clotting, within tumors. They found that in mice that received the engineered proteins via intravenous injections, the proteins led to clot formation almost exclusively within tumors, with only very limited thrombosis occurring elsewhere.

The clot formation is not the therapy itself, but rather creates conditions for efficient, targeted drug delivery to the clot-filled tumor, which Hu describes as a “cellular hive.”

“Once we have this clot formation at the tumor site, we have this so-called cellular hive that can attract these therapeutic drones,” Hu says.

In this case, the drones are blood platelets engineered with immunotherapeutics on their surfaces which the researchers inject once clotting has begun.

In their studies using mice, Hu and his colleagues found that the engineered platelets efficiently delivered a common immunotherapy drug known as an immune checkpoint inhibitor to the tumor sites. The checkpoint inhibitors encourage immune cells known as T cells to eradicate cancer cells.

Mouse models with colorectal tumors that received the treatment saw their tumors shrink and lived longer than mice that received a traditional immunotherapy treatment. Notably, one-third of the mice that received the treatment became completely tumor free.

The researchers then tested the delivery method with blood platelet derivatives — nanoparticles coated with a platelet membrane and loaded with a chemotherapy drug — on mouse models with human breast cancer tumors. Similarly, they found that the chemotherapy drugs were efficiently delivered to tumor sites while avoiding normal cells. The findings open the possibility to more effective and versatile cancer treatments with multiple types of drugs and fewer unintended side effects.

Before the delivery system can go to clinical trials, more testing is required to ensure its safety, especially with respect to clot formation. While their studies in mice have thus far shown that the system creates clots only in tumor sites, a more comprehensive safety evaluation is the next step, Hu says. That process will likely take a couple years.

An allogenic (from a donor) bone marrow transplant is a common treatment for blood cancers and other diseases of the immune system. During the transplant, the patient’s immune cells are replaced with the donor’s healthy cells. While the donor cells can help cure the patient’s blood cancer, they can also cause GVHD — in which donor T cells, a specialized immune cell in the blood, attack the patient’s healthy cells. This causes complications similar to an autoimmune disease that can be lethal.

Nicholas Hess

“Graft versus host disease is one of the most common complications after an allogeneic hematopoietic cell transplantation procedure, and the field knows quite well that the T cells from the donor are the ones mediating the disease,” says the study’s lead author Nicholas Hess, a scientist at UW–Madison’s Carbone Cancer Center. “Before this study, there was no finite T cell population that we’ve been able to identify as the cause of GVHD, so all our treatment regimens generally impacted the entire T cell population. But targeting all the T cells is not ideal, as they don’t just cause this detrimental disease, they also have a beneficial impact on the ability to prevent relapses.”

Today in Science Advances, Hess and collaborators including Stem Cell and Regenerative Medicine Center members Christian Capitini, professor of pediatrics, and Peiman Hematti, professor of medicine, published their findings, identifying cells called CD4/CD8 double positive T cells (DPT) causing GVHD in immunodeficient mice. To further confirm their findings, the researchers directly investigated human patient samples.

“We looked at over 400 clinical samples from 35 patients as a part of this study and found double positive T cells to be predictive of GVHD. We also found four other biomarkers which are predictive of not just GVHD, but also relapse in general,” says Hess. “Based on that, our next step is to merge the biomarkers into a machine learning algorithm that can output a risk prediction model. Clinicians could then use this model to understand a patient’s risk of relapse and GVHD.”

A team of physicians and scientists at UW–Madison is working on ways to address the problematic cells in patients while leaving healthy and helpful T cells to flourish. Hess says that while the team is very confident the double positive T cells are directly involved in GVHD, the key step in bringing this discovery to the clinic will be developing a targeted depletion strategy and this prediction model.

“When we can gain confidence in this biomarker research and our ability to identify patients at risk, then we will potentially be able to treat them before they have all the detrimental effects of this disease,” Hess says.

The study won a Best Abstracts Award from the American Society for Transplantation and Cellular Therapy and was presented at the American Association of Immunologists (AAI) and ECOG-ACRIN conferences, creating excitement based on the findings’ potential impact beyond blood cancer and transplantation.

“I’ve learned that DPTs have been found in a variety of chronic human inflammatory diseases, which goes to show that this is not a specific thing to graft-versus-host disease. It’s probably a wider phenomenon that these human T cells are doing that we’ve never really appreciated before,” says Hess. “It’s very exciting because it gives us something to study further. I’ve always been interested in taking something you discover in the lab and translating it to the clinic. I think it’s what gets me up every day. It is kind of the ultimate goal in my life to be able to say I participated in something that helped patients in some way.”

This research was supported by grants from the National Institutes of Health (T32-AI125231, T32-HL07899, UL1-TR002373, R21-AI116007, R01-AI136500 and R01-CA215461), National Science Foundation (EEC-1648035), St. Baldrick’s Foundation, the MACC Fund and the American Association for Cancer Research.