Saliva is often something people take for granted.
It helps break down food, maintain teeth and keep the oral cavity feeling comfortable. But head and neck cancer patients lose those benefits when chemotherapy treatments damage their salivary glands.
Olga Baker set out to research tissue regeneration for these cancer patients by collaborating with the Michael Petris and Gary Weisman labs after setting up shop four months ago as a new principal investigator at Bond Life Sciences Center.
Together, the Petris and Baker labs are looking at the role of copper in salivary gland damage.
“Nobody has asked what happens to copper metabolism during and after head and neck radiation,” Baker said. “Is copper related to the fibrosis that is developing in those patients, so they don’t make saliva? We don’t know. So, we are answering different questions…. We don’t have any data yet, but what we have is immunofluorescence studies showing that those copper transporters are present in salivary glands from mice and humans.”
If the two labs can learn how copper connects to salivary gland tissue regeneration, Baker can get a step closer to helping patients.
The Baker and Petris labs just published a paper with help from the Proteomics Center and the MU Molecular Interactions Core in the journal of Dental Research. Post doctorate Harim Tavares from the Baker lab is the leading author.
The study used synthetic networks of crosslinked polymer chains that can take in large amounts of water called, smart hydrogels. The smart hydrogels were used in the same mouse model as the cell sheets and promoted tissue regeneration on mouse salivary glands. The paper explored how different materials like smart hydrogels can improve tissue regeneration.
Baker’s other focus takes on cancer and tissue regeneration from a different angle in her collaboration with the Weisman lab.
“Dr. Weisman’s group has studied the mechanisms of salivary gland dysfunction for over 30 years, so between these two groups the tools are in place to provide a translational approach to understand and treat salivary gland disorders,” said Jean Camden, a senior research associate in the Weisman lab.
The two labs just submitted a paper on mouse submandibular glands and cell sheets, which are plastic-like sheets where cells grow and detach once it reaches a certain temperature. Kihoon Nam from the Baker lab is the corresponding author. The study transplanted submandibular gland cell sheets into a wounded mouse to see if cells could be transferred.
“We believe that is a good proof of concept for future use in radiation studies,” Baker said.
The Baker lab uses cell sheets with the Weisman lab to study the role of the P2Y2 receptor in salivary gland regeneration. P2Y2 is a plasma membrane receptor that binds the molecules outside of cells and serves as signals to trigger an action.
The Weisman lab previously showed that P2Y2 receptor activation encourages salivary gland cells to migrate together and form a unit capable of secreting saliva.
“At this time, we don’t know what the role of P2Y2R is in the cell sheets,” Camden said. “That is an aim we proposed in a recent TRIUMPH proposal.”
The TRIUMPH initiative — The Translational Research Informing Useful and Meaningful Precision Health initiative — is a pilot grant funding opportunity through the Missouri School of Medicine.
As if two collaborations weren’t enough, Baker is also working on saliva substitutes. The lab just submitted a grant to fund the project.
“If we get the money, we will be able to make a far better saliva substitute as compared to the Biotine, or Aquoral, or Oasis,” Baker said. “Those are the three leading brands. So, hopefully, we can make something better here at MU and commercialize the product.”
Vaccine development remains a central goal to get the current COVID-19 pandemic under control. While vaccines are highly vital in the fight against the current pandemic, what if scientists could prevent the virus from entering cells altogether? Researchers at Bond Life Sciences Center are working to do just that and, so far, they’re the only ones at Mizzou on the case.
For the Gary Weisman lab, that starts with their study of a family of purinergic receptors which are found on the plasma membrane of cells. Molecules outside the cell bind to receptors and serve as signals to trigger an action, whether it’s transporting something into a cell, alerting its defenses or initiating programmed cell death. The specific receptors they study sound off one of the first alarms to alert host immune cells when a cell is damaged.
Weisman, Bond LSC principal investigator and Curators’ Distinguished Professor of biochemistry, noticed that the spike protein in the virus that causes COVID-19, SARS-CoV-2, shares an amino acid sequence — arginylglycylaspartic acid or RGD — with one of the receptors his lab studies named, P2Y2.
“So, we had this one niche that no one I think has followed,” Weisman said. “Even though people understand RGD sequences are important for protein to protein interactions, and possibly viral entry, no one has looked at this with respect to coronaviruses.”
While ACE2, a plasma membrane receptor, serves as the primary cell-surface receptor for SARS-CoV-2 binding, a potential role for the RGD sequence in the spike protein is to bind to alternate receptors and subsequently enhance viral infectivity.
“We postulated that if there was a way to use our receptor, it might be to block the entry of the virus,” Weisman said. “The virus can’t replicate on its own. It has to get inside the cell to be replicated, so if we prevent the entry, we can potentially stop the infections.”
They found plasma membrane receptors like ACE2 and P2Y2 all share this sequence that binds to other cell-surface receptors called, integrins. The lab is currently exploring ways to block these pathways without blocking other functions.
Few other labs have made this connection because RGD is not known to be present on many of the membrane receptors. In addition, the Weisman lab already has the supplies and connections to study these receptors.
“We, as the lab, have been studying this receptor and this family of receptors for so long that if there is a lab that has the tools and the knowledge to answer this question, I definitely think that is us,” said Kevin Muñoz Forti, Ph.D. candidate for the department of biochemistry.
The lab partners with Kamal Singh, assistant director of the Molecular Interactions Core at Mizzou and associate research professor in the department of veterinary pathobiology, who works with viruses in a way that won’t infect workers.
Singh achieves this by using look-alikes, or pseudovrises, of the spike protein on SARS-CoV-2. To the cell, this mimics the outer shell of SARS-CoV-2, but is not contagious.
Even though the Centers for Disease Control and Prevention and Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, expect a vaccine soon, this work is for the long run.
“I can guarantee you this isn’t the last coronavirus that will come up,” Singh said. “There will be many because it has been kind of periodic lately. Coronaviruses have been emerging, so the research done in collaboration with Gary’s lab will definitely be available for… future coronaviruses.”
Coronaviruses are a family of viruses which may cause respiratory illness in humans. The most recent diseases, before COVID-19, caused by previous coronaviruses were Severe Acute Respiratory Syndrome (SARS) from 2002 and Middle East Respiratory Syndrome (MERS) from 2012. Severe Acute Respiratory Syndrome Coronavirus 2 is the virus that causes COVID-19.
“This is the virus that causes COVID-19 or SARS-CoV2,” said Lucas Woods, Weisman research lab manager. “If this type of research were to have been investigated during the first coronavirus epidemic, there might have been some type of lead on the type of work we’re doing… so, absolutely this work will be useful after a vaccine or treatment is available.”
Looking ahead, the study has two years of funding from the American Lung Association in addition to grants from the National Institutes of Health. The Weisman lab hopes to eventually make it to clinical trials, but the road from basic research to clinical trials is long and arduous.
“What’s on our side, at least for the future, is that with some of these pathways we’re looking at, there are already available drugs that target these particular pathways,” Woods said.
These pathway-blocking drugs aren’t approved for humans yet, but this research could facilitate clinical scientists to test the safety of these or related drugs in humans.
The Weisman lab’s research of P2 receptors can be applied to many systems in the body and other diseases. This also allows for more ways to receive grants to fund studies longer. Along with the COVID-19 studies, they study P2 receptors in diseases that affect salivary glands.
Cheikh Seye, Mizzou professor of biochemistry, studies vascular diseases that relate to the receptors studied by the Weisman lab. Seye understands that one of the complications of COVID-19 in humans is vascular related.
“I mean there’s a lot of interaction between the vasculature and other systems, so it doesn’t stay with the salivary gland,” Seye said. “It’s all interconnected, so that’s why we need to have a multi-dimensional approach.”
In addition, the lab has found commonalities between oral and lung epithelial tissue that may contribute to COVID-19.
While this study has quite a bit of potential, it’s a long way away from seeing practical results.
“All the people in the lab have confidence because they have been successful on their own doing this before,” Weisman said. “So, it’s just another challenge, but we know how to get the answers, we have the tools and we’re optimistic that we’ll find out something.”
Researchers working on this study include Gary Weisman, Kamal Singh, Lucas Woods, Cheikh Seye, Jean Camden and Kevin Muñoz Forti.
Olga Baker, professor of Otolaryngology, will join Bond LSC June 1, 2020, as our newest principal investigator with a focus on inflammation. | photo by Roger Meissen, Bond LSC
By Lauren Hines | Bond LSC
Olga Baker is the type of person who acts when she sees a problem.
In her home country of Venezuela, Baker worked as a dentist who was part of a team that treated head and neck cancer patients.
“They told me how much they suffered as I used to do their cavities and fix their teeth,” Baker said. “That’s how I became so motivated, because I saw their suffering myself.”
These patients stopped producing saliva due to radiation from their head and neck cancer treatments that destroyed their salivary glands.
“Because they look okay everybody thinks they’re normal and they’re healthy,” Baker said. “Nobody knows the suffering that is ongoing inside them, so this brings a lot of psychological burden for these patients.
That motivated Baker to enroll in a biochemistry Ph.D. program at the Central University of Venezuela which she completed in 2003.
Ever since, Baker has been studying salivary glands, tissue regeneration and Sjögren’s syndrome at multiple universities
That passion led Baker to Mizzou initially as a post-doctoral fellow in 2003.
Baker moved from her post-doctoral fellowship to become a senior researcher at Mizzou but left in 2009 for the State University of New York Buffalo to accept an assistant professor position as an independent investigator to gain more experience. In 2014, she then moved to the University of Utah School of Dentistry as a tenured associate professor.
Baker officially returns to Mizzou on June 1 as a full professor in the departments of otolaryngology-head and neck surgery and biochemistry to collaborate with former colleagues as LSC’s newest principal investigator
“I later on decided that it would be nice to be close to home because my husband is from Missouri,” Baker said. “So, working with many people who helped me to be here, I applied to MU and made my decision to come back after seeing all the possible scientific collaboration with great colleagues.”
This time around, Baker will have her own lab to find ways to treat salivary gland hypofunction and to develop the products that sprung from prior work at the University of Utah where Baker created her own business
She aims to further create and distribute saliva substitutes in her business venture using proteins in saliva called mucins. Baker isolates mucins from plants and animals to be used as a mouth spray to moisturize people’s oral cavity who otherwise can’t produce saliva.
“So then with that they can eat better, they can talk better, and that lasts long in their mouth,” Baker said.
Baker plans to bring it to market while working at Mizzou.
Due to having so much expertise in the salivary field, she’s also studying how to prevent COVID-19 from infecting patients through saliva
“COVID-19 is found in saliva, and that’s very important because we could find ways to prevent transmission if you block the entry into saliva. So that’s a new area of interest for my lab.
Baker will be opening her lab on the fifth floor working on inflammation. She plans on being part of the inflammation group at the LSC with Michael Petris and her former colleague Gary Weisman
“I think it will be very rewarding for us at Bond LSC if she locates a lab there because there are people ready to work in her area of research with her,” said Weisman, Curator’s Distinguished Professor of biochemistry.
Baker and Weisman plan on further studying Sjögren’s syndrome, an autoimmune disease that also causes dry mouth, dry eyes and a number of other systemic symptoms.
When Baker isn’t fighting for a cure, she enjoys her other passion — singing and dancing.
She was a lead singer of a band called, Peña Flamenca, who used to play in the Music Café (now known as Café Berlin) and also appeared on a TV show, Pepper and Friends, as part of Hispanic Heritage Month.
Even though she isn’t part of a band anymore, she still dances.
“I really enjoy that part of my life, being a singer and dancing and bringing joy to people,” Baker said.
Baker’s mission is to solve the oral health problems she encountered, and her journey isn’t over yet.
#IAmScience because I get to spend the rest of my career being curious and creative, answering challenging questions, and making my small contribution to our collective body of knowledge.
What does competitive swimming and cancer research have in common? For Kimberly Jasmer, the intense world of competitive swimming has guided her towards obtaining her Ph.D. and studying cancer at the University of Missouri.
Learning to swim was imperative for a girl growing up on the coast in North Bend, Oregon, and she fell in love with the water. That love led to a competitive swimming career that began at the age of nine and continued for 16 years, through the third year of her Ph.D. program at MU.
But Jasmer was set on conducting cancer research since high school after her grandmother contracted breast cancer twice throughout her life.
While an undergraduate at the University of Washington in Seattle, Jasmer visited MU for a swim meet. The trip also presented her with the opportunity to speak with Steve Alexander from the Division of Biological Sciences.
“I came out here for a swim meet and set up an appointment with Dr. Alexander and he was very confused why this random swimmer from Washington wanted to meet with him. We ended up having a really great conversation and I applied to graduate school here,” said Jasmer. “Mizzou provided me the ability to do the research I was interested in and also continue my swimming career and it was one of the few places that I could do both of those things.”
Now, 10 years later after starting her program at MU, Jasmer has earned her Ph.D. in Biological Sciences and is three years into her post-doc in the Petris and Weisman labs.
During her time at MU, her research has evolved, but it always ties back to cancer research in some way. For her Ph.D., Jasmer studied a specific enzyme, Heme oxygenase 1, in the body that has the capability to promote tumor growth including melanoma if overproduced.
“Heme oxygenase 1 is considered a protective enzyme but too much can promote cancer,” said Jasmer. “You need enough to protect yourself from DNA damage caused by oxidative stress but not so much that it can lead to other unintended consequences, such as melanoma.”
After, she began her post-doc in the Weisman lab researching Sjögren’s syndrome — an autoimmune disease affecting the salivary and lacrimal glands ability to produce saliva and tears that carries with it an increased risk of developing lymphoma — she has honed in on looking for drugs that inhibit inflammation in the salivary glands to improve saliva flow and minimize the risk of lymphoma development.
Looking to the future, Jasmer has applied for a National Institutes of Health (NIH) grant that would extend her post-doc for one to two years and provide funding for the first three years of a faculty position. The grant would allow Jasmer to begin her own research on finding a radioprotective therapy, which would shield patients with head and neck cancers from the unintended consequences of radiotherapy. This research is connected to her current work on Sjögren’s syndrome because radiation can cause the inability to salivate and produce tears.
This research hits close to home because her uncle suffered from a tumor in his nasal cavity. The radiation he received caused him to lose the ability to produce tears and taste most foods. “I’ve seen the effects of radiation firsthand, and it’s hard for him that he can’t taste anything anymore,” Jasmer said.
Jasmer’s focus and intensity extends to all the goals throughout her life. In her swimming career, Jasmer made it to the national championships and qualified as an All-American for three years swimming at the college level. Additionally, she qualified for the 2008 and 2012 Olympic trials in Omaha, Nebraska.
Although she didn’t qualify for the Olympic team in 2008, she was determined to make a comeback in 2012. Before the 2012 trials, she tore her labrum but was able to recover within a year and qualified again. While not making it past the trials for the second time, Jasmer was proud of all she was able to accomplish within her swimming career.
After her second round at the Olympic trials, she decided to take a step back from swimming. After her time on the MU swim team, she hadn’t returned to the Mizzou swim deck since 2012 until last week.
“Before, swimming reminded me of the disappointment because my career hadn’t turned out as I planned,” said Jasmer. “Now it takes me back to the happy enjoyment of being in the water. When I went swimming last week, it reminded me of what I loved, which is being in the water.”
Now, as a mom, Jasmer hopes her daughter finds passion in an activity as much as she found in swimming.
“I took her to mommy-and-me swim lessons this past spring. I want her to know how to swim and be safe, but I don’t know that I care if she swims or not,” said Jasmer. “My parents had no knowledge of swimming and I think it was fun for them to learn a completely whole new world. So, if she decides that she wants to do an activity that I know nothing about, I just hope she finds something that she’s passionate about.”
Aside from swimming and research, Jasmer serves as the chair of the MU post-doc association board.
“I’m passionate about helping other people develop their own transferable skills they’ll need for their career because it’s easy to just end up doing research and not develop the rest of the skill set needed,” said Jasmer.
She also loves exercising through CrossFit and lifting weights as well as spending her time outdoors, hiking, camping and going on float trips with her friends. She has even taken her daughter Sofie hiking with her in Whistler.
Bond LSC scientist internationally recognized for work on salivary glands and autoimmune disorders
By Phillip Sitter | Bond LSC
You might not think too highly of spit, but you would quickly regret not having any.
People with Sjögren’s syndrome suffer chronic dry mouth and eyes from an overzealous immune system that attacks salivary and tear ducts, causing serious health issues.
Gary Weisman’s research might hold the key to understanding and managing this immune response, leading to effective treatment or even prevention of this ailment.
For this, the International Association of Dental Research, or IADR, awarded him the 2016 Distinguished Scientist Award for Salivary Research. Weisman accepted the award in June at the opening ceremonies of the IADR conference in Seoul, Republic of Korea.
“We want the good, but not the bad,” said Weisman, a Bond Life Sciences Center investigator, of what we ideally want from our immune system’s functions.
Mice with un-checked autoimmune disease of their salivary glands have their glands destroyed. The disease can spread to other secretory organs next. An over-reactive immune system on a civil war-path can extend its damage to cause pancreatic failure and death.
The destruction wrought by Sjögren’s syndrome is self-inflicted, caused by an overreaction of our bodies’ defenses against infection and injury. This is what an autoimmune disease is.
But, our bodies’ immune cellular response team is complicated. Weisman said dozens of different cell types have been isolated and identified as part of the immune system, and he likens the immune system to fire, police and construction services in human society all working together.
While firefighters are meant to prevent further damage from an inferno, sometimes our bodies’ first responders start doing the equivalent of using dynamite to stop the spread of a fire.
In chronic inflammation, that autoimmune response can mean a burning, throbbing, constant pain. The key to a healthy immune response is balance. The balance has to be between containment and repair of damage caused by infection or injury and damage caused by chronic inflammation if that emergency response continues unabated.
Weisman has spent almost 30 years studying how to prevent our bodies’ immune system from over-reacting to threats and causing further harm.
Earlier in his career, Weisman studied how extracellular ATP plays a critical role in immune responses, and how too much of it can cause the over-reaction that leads to tissue destruction in autoimmune diseases. ATP, or adenosine 5’-triphosphate, is the main molecule used for energy in cellular activities inside cells. Weisman was one of the first scientists to study how damaged cells release ATP as a distress signal.
The released ATP signals receptors that “send out the alarm to the fire station” — the body’s immune cells, he said.
Once he understood this, Weisman began to manipulate the actions of released ATP to see how that would affect an immune response.
Mice with salivary gland autoimmune disease got healthy when the released ATP was prevented from activating their receptors on the surface of cells. Preventing the ATP receptors from being activated slowed down and even stopped the advance of autimmune disease.
Conversely, if you prevent the activation of the ATP receptors in lab mice with Alzheimer’s disease they die much more rapidly from the disease, Weisman said, suggesting that activation of immune cells by ATP is beneficial in slowing the progression of this disease.
Alzheimer’s disease and autoimmune diseases such as Sjögren’s syndrome are only some of the inflammatory diseases that Weisman has studied. With each of these diseases, the role of ATP receptors has to be investigated individually, suggesting that Weisman’s work may extend beyond salivary glands and the brain to other parts of the body.
“Our [ATP] receptor is also involved in heart disease,” Weisman said, and he added that other diseases like cystic fibrosis, cancer, lupus and arthritis have inflammatory components, too.
For now, we all fight a losing battle when it comes to our bodies’ management of the immune system. As we and our immune system age, it has the potential to destroy more than it protects and “eventually you could slip over to the dark side and die,” Weisman said.
In the meantime, Weisman said that a better understanding of the immune system could lead to more effective, targeted treatments of chronic inflammation and other autoimmune disorders. This could provide a new approach to control undesirable activation of the immune system beyond the use of with anti-histamines, anti-cytokines and ibuprofen.
Weisman is a Curator’s Distinguished Professor of Biochemistry. He began his salivary gland research at MU 27 years ago with Professor John Turner, before Turner’s retirement. Since then, his research has been continuously funded by the National Institutes of Health, where one of his recent grants was well scored and will likely be extended for another five years.
Jean Camden and Luke Woods have an ant’s-eye view of Alzheimer’s disease.
Both are bench scientists in the laboratory of Gary Weisman, a professor of biochemistry at the Bond Life Sciences Center. Jean has spent the past 12 of her 35 years at the University of Missouri in the Weisman lab, running experiments, managing the lab and working with students. Luke joined the Weisman lab six years ago, doing what he call’s the dirty work of science: “Gary does the writing and the NIH stuff, but down in the trenches — that’s me and Jean.”
Q: What does your lab do, and how does it involve Alzheimer’s?
Luke: We primarily have two projects. One, which has been a very longstanding project, is focused on salivary glands and salivary gland inflammation. The other is the Alzheimer’s project. The link between them is a particular type of cell surface receptor called a nucleotide receptor — more specifically, a P2 nucleotide receptor called P2Y2. These P2 receptors function in a lot of different ways, but the link is with inflammation: We look at P2 receptors in salivary gland inflammation and in Alzheimer’s disease, which has a very large inflammation component that often gets glossed over. In a lot of Alzheimer’s articles that the public reads, you hear about amyloid beta plaques and tau tangles and neurodegeneration, but a large component of that is inflammation, where some of the resident non-neurons in the brain start responding like there’s inflammation in the brain, and it actually kills neurons. That’s been the focus in Gary’s lab for the past 30-plus years.
JEAN: The P2 receptors — especially the P2X7 and P2Y2 which we focus on — Gary during his postdoctoral work started studying these receptors without really knowing that they existed. At the time, he just knew that there was a pore formed in cells caused by the addition of the nucleotide ATP which eventually leads to apoptosis (cell death). Eventually, we cloned the human P2Y2 receptor gene with another group in North Carolina, so we call it “our receptor.” It only appears in cells under inflammatory conditions, such as Alzheimer’s disease, salivary gland autoimmune disease and cardiovascular disease. Any time you have tissue damage, it looks like the P2Y2 receptor is up-regulated. And then once the damage is healed, the receptor goes away.
Inflammation is good — we want inflammation, that’s how we heal — it’s the chronic inflammation that’s bad. But we really don’t know how these receptors work and what their role is during chronic inflammation. Do we want to activate them, or do we want to inhibit them?
LUKE: Scientists have investigated P2X7 receptor antagonists in the treatment of Crohn’s disease and rheumatoid arthritis — there are several clinical trials that have been focused on these receptors, evaluating whether you want to block or activate them. If you block them, you prevent the acute inflammatory responses that are good for wound healing; if you activate them, you may extend those responses past the healing phase into a chronic inflammatory phase that can be quite damaging. So unraveling that fine line of what you want to be doing to these receptors in disease settings is sort of what we do here.
Q: When I think of Alzheimer’s, I think of a shriveled, shrunken brain, but I associate inflammation with swelling. Why the difference?
LUKE: I think the distinction is acute versus chronic inflammation. With acute inflammation, you get swelling. The body has different types of immune responses: acute responders like neutrophils and macrophages are immune cells that act quickly. They come in, for example, if you have a scratch, and there can be swelling. Along with macrophages neutrophils can protect cells from bacteria. The macrophages can also clean up damaged tissue and then the repair cells go to work. Cells come in that lay down a new matrix, whereas undamaged cells then migrate onto the matrix and regenerate. Well, what happens after you’re done repairing is that there are signals that tell the inflammation to stop. In chronic inflammation, that’s where you have continued cell death, and the tissue would then shrivel up. The shriveled brain that you’re referring to is during chronic inflammation, and that’s an end-of-life case, after a very long bout with Alzheimer’s.
JEAN: What we think of as inflammation is often a cut or a wound. It’s only been in recent years that Alzheimer’s disease has been considered an inflammatory disease. We have a phenomenal immune system, but when it goes awry, you have problems. In the other disease we look at — an autoimmune disease — your immune system starts to attack your own body. It’s hard to treat and understand the underlying mechanism.
Q: So how are you trying to unravel the role of inflammation in Alzheimer’s?
JEAN: To study Alzheimer’s, we have an Alzheimer’s mouse model. It overexpresses a gene for the amyloid precursor protein that enables the brain to accumulate high amounts of beta-amyloid plaques that you always hear about. So we’re using this mouse model that we’ve crossed with a mouse that does not express any P2Y2 receptor, so it’s called a knockout mouse. The P2Y2 receptor knockout mouse by itself is fine, and the Alzheimer’s mouse does develop Ab plaques, but it lives to approximately 6 months old before it will develop behavioral defects. The interesting thing is that when we cross the P2Y2 receptor knockout mouse with the Alzheimer’s mouse, the offspring that are Alzheimer’s mice without P2Y2 receptors prematurely die. So at least in this Alzheimer’s mouse model, it looks like the presence of the P2Y2 receptor is protective, because without it, the Alzheimer’s mice die much earlier. But we don’t really know which cell type is most important: Is it the P2Y2 receptor up-regulated on neurons that acts to repair them —which we’ve already shown happens — or is it the P2Y2 receptor on microglia (an immune cell of the brain), or is it the P2Y2 receptor on blood vessels in the brain that help recruit immune cells from the cardiovascular system to help with repair?
So we’re using this mouse model to investigate the role of the P2Y2 receptor, plus we also use cell lines because we can easily control the environment for these cell lines in culture. We isolate primary neurons, we can prepare primary microglial cells or we can purchase cell lines that comprise blood vessels. We can then utilize these tools to investigate cell signaling mechanisms for the P2Y2 receptor in individual cell types.
LUKE: One of the findings that we have found interesting in these primary cells is when you take them fresh out of the mouse, put them in a dish and then treat them as you wish. We’ve shown that if you activate the P2Y2 receptor in primary microglia from the mouse, they will actually engulf and chew up beta-amyloid. And so one of the things we think might be happening in this Alzheimer’s mouse model is that P2Y2 receptor activation in these microglial immune cells in the brain is working to break down those beta-amyloid plaques. And when you lose the P2Y2 receptor in that mouse model, those plaques develop quicker because the immune cells are no longer offering protection by chewing up that beta-amyloid. That’s one of the hypotheses we’re exploring right now.
Q: So you’d bet that these receptors are actually protective against Alzheimer’s?
JEAN: Yes. Going back to the human — it’s hard to get human tissues, especially brain tissues, but there is one published study that has shown that in Alzheimer’s patients who have passed away the P2Y2 receptor is down-regulated, meaning there’s not much left. Which would make sense. If it’s down-regulated, the plaques aren’t able to be chewed up, per se, by these microglia. There’s a correlation between low levels of P2Y2 receptors and Alzheimer’s disease that is apparent at the end of life.
LUKE: It’s very difficult to do some of these studies in humans because most of the available Alzheimer’s tissues are from end of life cases where you can only look at the end result of the disease without looking at the progression of the disease. Obviously you can’t take brain tissue from a living person, so the ability to study live cells from Alzheimer’s patients is limited. We rely very heavily on mouse models.
Q: What have been the biggest shifts in our understanding of Alzheimer’s in recent years?
LUKE: Maybe one shift — I may not be the best expert to speak about it — is the idea that the beta-amyloid plaques are the cause of disease. It is now being mostly recognized that they’re really the tombstones of the disease. They’re not the initial cause, but rather the end result of the disease. For a long time investigators were focused on trying to prevent the buildup of beta-amyloid because that was one aspect of Alzheimer’s disease that you could see and measure. Now the thinking is that maybe the beta-amyloid does not contribute as much to disease progression as originally thought, and rather is the end result of a complicated mechanism that is actually causing the neurodegeneration.
JEAN: There’s still debate on what causes Alzheimer’s disease. There is a small percentage of patients where it’s actually related to a genetic alteration in the amyloid precursor protein gene.
LUKE: Another link has been with the ApoE (apolipoprotein E) gene, which makes a lipoprotein and cholesterol transporter. We inherit 1 copy of the ApoE gene from each of our parents and it has been shown that individuals who have at least 1 copy of a particular variant of the gene called ApoE4 are at increased risk of developing Alzheimer’s disease.
Q: From the perspective of a lab scientist, why do you care about Alzheimer’s?
JEAN: We care about any disease, really, and if we can show that our receptors have anything to do with any disease, we’d be proud to have a role in that.
LUKE: We don’t do much clinical science here, it’s mostly basic science. We contribute to the basic understanding of the disease so that drug companies and medicinal chemists who develop drugs for clinical use in Alzheimer’s patients can say, “Hey, this group’s research found a new mechanism related to Alzheimer’s disease, so let’s target this pathway to treat the disease.” It’s always nice to contribute to that sort of ground-level science.
JEAN: That would be the ideal, to show that whether you have to activate or inhibit the P2Y2 receptor, it does something to improve the clinical outcome in Alzheimer’s patients. A better understanding of Alzheimer’s and other diseases is what’s needed — we’re just working to provide a piece of the puzzle.
Q: How has being down in the trenches changed your perspective on research and Alzheimer’sin general?
JEAN: We’re the ones who are hoping to clarify the direction for science to go. We do the experiments and we are the first ones to see the data. We collect the data that becomes the cornerstone for deciding the direction our research goes. I think Gary would agree with that — he depends on us a lot to collect the data and we depend on him to help determine which scientific findings to chase and which ones not to chase.
I’ve been doing this for 35 years, and I really do enjoy the science. I’ve seen the science of these nucleotide receptors come a long way. These receptors have in common their use of extracellular nucleotides, particularly ATP (or adenosine triphosphate, more commonly known as the intracellular high energy molecule of all cells). And this ATP, is at a high concentration inside cells, so when it is released by cell damage, it can easily activate nucleotide receptors on nearby cells. It was Dr. Geoffrey Burnstock, now considered to be the grandfather of nucleotide receptors, who claimed a long time ago that there are receptors on the outside of cells that respond to ATP. Everybody kind of laughed at him, “Yeah, sure, right. There’s no way: ATP belongs inside the cell.” So for me personally, to come in on the ground level for these receptors and find a role for them in a variety of diseases has been exciting for me.
LUKE: ATP is the energy currency inside of all cells, so it’s use outside cells would be like tossing money out the window. Why would they want ATP outside the cell? It didn’t make any sense at the time, but looking back I think it does. What happens if you damage or rupture a bunch of cells during an injury? You get the release of a high concentration of ATP that neighboring cells recognize as a danger signal telling them that an injury has occurred. In that sense, ATP makes the perfect signaling molecule to tell other cells that an injury has occurred and they need to start the repair work by recruiting immune cells to the damaged tissue.
Q: Where would you like to be in five years with this research?
JEAN: I talked about determining how the P2Y2 receptor in this mouse model was protective. It would be nice to find out which cell type on which the P2Y2 receptor is expressed in contributes most to neuroprotection. Our hypothesis would be that the microglial cells are very important, since they gobble up beta-amyloid, but other cell types including neurons and endothelial cells are likely involved. We’re also anxious to look at other inflammatory diseases to see if the P2Y2 receptor plays a similar role there.
LUKE: From somebody who does a lot of bench work, something I would like to see is a really good tool, a specific agonist or antagonist of the P2Y2 receptor that could be used in the clinic. There are a few suitable compounds available that we use to investigate the P2X7 receptor— I’ve told you that some have been tested in clinical trials — but the P2Y2 receptor has been sort of an enigma, due to the lack of selective inhibitors and agonists that are specific enough for clinical use. I’d like to see the development of a specific agonist or antagonist that could eventually be used to treat inflammatory diseases. There’s no reliable drug that is currently suitable to investigate the P2Y2 receptor in animals or humans, so clearly more work is needed there.
This interview has been edited for length and clarity.
By Paige Blankenbuehler | MU Bond Life Sciences Center
There’s a criminal on the loose, striking every day. Millions fall victim, but there’s still no way to stop it. And, in all likelihood, you have been hurt by it.
If inflammation is an unsolved criminal case of the last three decades, then Gary Weisman has been the detective. He’s certain there’s an accomplice — perhaps many — that may be triggering the discomfort.
The Bond Life Sciences Center investigator is slowly revealing what makes inflammation tick and what makes it strike. Each epiphany brings another question. He’s certain there’s a way to prevent negative effects of unsolved inflammation.
Weisman has dedicated his career to understanding the micro-processes behind inflammation. He’s become so specialized that his techniques can be as hard to crack as the case itself.
“I would not ask anyone to explain what I do,” Weisman says. Nonetheless, he’s been able to divide the process of inflammation into two categories: components that repair the body and components that lead to its destruction. This will help find inflammation’s many accomplices to figure out why humans work, and what their bodies do when they don’t work so well.
“I am interested in the meaning of life,” Weisman says. “Life has become simpler for me because the scientific method carries everywhere. I’ve become aware of how simple we are as a machine.”
Criminal or just misunderstood?
Most criminals adopt patterns, but inflammation stands as a signpost for mysterious, underlying problems.
Its effects are usually localized: an arm, a joint, the brain or a gland. You feel a temperature spike then the skin reddens in a part of your body. Later still, the skin tightens and pain comes at a snail’s pace.
Not even cells are safe. Inflammation even strikes on the molecular level.
But really, inflammation can be a good thing. It’s part of the immune system’s bag of tricks to signal the body to bring in reinforcements to fight off the invasion. Normally, inflammation corrects a physical problem, but if it is not successful in repairing a problem, inflammation can become chronic and accelerate tissue destruction.
Just like in an episode of CSI, Weisman puts the pieces of the inflammation puzzle together in his office by applying the expertise of Laurie Erb, Jean Camden and Lucas Woods — all donned in white lab coats, eyes pressed to the microscope examining evidence and building molecular evidence in the case.
The MU associate professor of biochemistry and his team have become a sort of grant-wielding wizards to sustain his pursuit of inflammation triggers. National Institutes of Health grant awards have sustained his lab for decades. The funding has come from varied sources such as the MU Food for the 21st Century Program, the Bond LSC, the Bright Focus Foundation, the American Heart Association and the Cystic Fibrosis Foundation. In recent years, research funding for Alzheimer’s disease and Sjogren’s syndrome (a disease of the salivary gland that causes dryness) have contributed, too.
But the funding source doesn’t matter because inflammation is the tie that binds.
Advancements, like recent mapping of the human genome, have moved his work forward to understand inflammation’s complexity. Each experiment he completes fills in another blank slate in the “human owner’s manual.”
“As humans, we’re so intent on the fact that we’re superior to all, but really we’re not,” Weisman says. “With the Human Genome project, we’ve come to understand that all living things have similar designs … we are on the verge of finding revolutionary solutions to preventing or reversing human diseases.”
A receptor all our own
One specific player in the body’s immune system has kept Weisman’s attention for most of his career. The P2Y2 protein is a nucleotide receptor, and his lab team members affectionately refer to it as “our receptor.”
Nucleotide receptors are regulatory molecules in red blood cells. What they regulate is nuanced, mostly undetermined and of great interest to scientists. Answering that question has become Weisman’s wheelhouse.
The body manufactures 15 different types of nucleotide receptors, all similar in construction, but each are believed to have subtly different functional roles. It’s as if Weisman and his lab is on the case of a highly organized crime ring.
“Our receptor is mainly present when inflammation occurs, and we’re trying to figure out its role in a variety of diseases,” Weisman says.
The P2Y2 receptor has been observed in Alzheimer’s patients, along with a plaque build-up in the brain, and the receptor was suspected of playing a role in the disease’s progression.
Weisman and his colleagues found that the deletion of the P2Y2 receptor in a mouse model of Alzheimer’s disease accelerates progression of plaque build-up, neurological symptoms and death. This suggests that the receptor has anti-inflammatory effects rather than being “guilty by association” with the tissue-destructive aspects of inflammation.
“It’s like I have this 30,000-piece jigsaw puzzle in front of me that I have to put together,” Weisman says. “What’s the difference between you and me? As a machine, surprisingly very little.”
This simplicity drives Weisman to continue solving the mysteries of inflammation and search for its underlying chemical processes. By understanding the body’s chemical reactions, he believes treatments can be developed to focus the immune system on repairing damaged tissues.
Through studying his receptor, Weisman is breaking up inflammation’s crime ring.