Microbiology

Why an overactive immune system attacks the bodies of people with lupus but still leaves them vulnerable to infection

by

no photo placeholder image

Why an overactive immune system attacks the bodies of people with lupus but still leaves them vulnerable to infection

Profile
Andrew Monteith, University of Tennessee

Despite having an overactive immune system, people with lupus may still struggle to fight bacterial infections. My team and I found that this paradox may be because chronic inflammation pushes their immune cells toward the wrong kind of response.

To understand why an overactive immune system can still fail to control bacterial infection, we focused on neutrophils, which are white blood cells that are among the first to respond when bacteria enter the body. Neutrophils can release webs of DNA and antimicrobial proteins called neutrophil extracellular traps, or NETs, that can trap bacteria, limiting their spread and killing them.

Scientists often discuss these traps as if they are all the same, but the body can produce NETs through different pathways, and they do not all work equally well.

For example, healthy neutrophils responding to infection from Staphylococcus aureus can sense lactate, a chemical byproduct made by the bacteria. That signal helps trigger neutrophils to release a type of NET that serves as a trap rich in antibacterial proteins, but also kills the neutrophil.

In lupus, my team and I found that inflammatory molecules interfere with this antibacterial response in mice. These signals reduced levels of a protein needed to sense bacterial lactate. At the same time, another inflammatory molecule pushed neutrophils toward another form of NET it could release more quickly, sparing the neutrophil but less effective at killing bacteria.

The result is not an immune system that is weak, but an immune response that is highly active but misdirected.

Why it matters

Lupus is usually described as an autoimmune disease in which the immune system attacks the body’s own tissues. But serious infections are also a major concern for people with lupus. Some of that risk comes from medications that suppress the immune system, but the disease itself can also alter how immune cells function.

Our findings help explain why more inflammation does not necessarily mean better protection from infection. The type and timing of the immune response matter.

We also found that treatments currently used for lupus can correct specific defects in these neutrophil pathways. Our results do not show that people taking standard lupus treatments will have fewer infections, but they do suggest that existing therapies can correct immune defects that may contribute to susceptibility to infection.

What still isn’t known

The immune system is more complicated than one cell type or one response. Although we found that standard lupus treatments reduced the number of bacteria in several organs in lupus-prone mice, they did not significantly improve survival compared with untreated mice. Other immune cells, tissue damage and additional features of lupus likely contribute to poor outcomes during infection.

There is also an ongoing debate about what neutrophil extracellular traps actually do in lupus. Some studies have found that disrupting pathways required for NETs to form does not necessarily improve lupus, challenging the idea that simply making more NETs drives the disease.

Lupus can cause physically and emotionally painful symptoms.

Our findings suggest that what kind of NET neutrophils make and under what circumstances may be more important questions for lupus. During infection, lupus neutrophils may produce a type of NET that is less effective at killing bacteria while still releasing inflammatory material. That combination of poor infection control together with an inappropriate inflammatory response might exacerbate lupus.

What’s next

My team and I are now focused on understanding how different types of NETs affect autoimmune disease and infection. Rather than treating all NETs as the same response, we want to define how different NETs are generated, what they contain and whether particular kinds are protective or harmful in different contexts.

Understanding how lupus changes the type of NET response produced during infection may help explain why disease activity, infection risk and treatment response vary among patients.

The Research Brief is a short take about interesting academic work.The Conversation

Andrew Monteith, Assistant Professor of Microbiology, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Buchan Heads Microbiology Department

by

no photo placeholder image

Buchan Heads Microbiology Department

Profile
Alison Buchan.

Professor Alison Buchan is focused on continuing research excellence and preparing the next generation of scientists as she leads the department.

The new head of the Department of Microbiology at the University of Tennessee, Knoxville, has more than a decade of experience in leadership with the department. 

Alison Buchan, Carolyn W. Fite Professor and David and Sandra White Professor, joined UT in 2005 as an assistant professor and became associate head of the microbiology department in 2012.

“It is both an honor and a tremendous responsibility to serve as department head,” she said. “Having spent my entire faculty career at UT, I’ve had the opportunity to watch this department grow and evolve, and I’m excited to help guide its next chapter.”

“UT microbiology uniquely bridges environmental, medical, and applied microbiology, studying microbes from Earth’s most diverse environments to their roles in climate, health, disease, and biotechnology,” Buchan said. “My goal is to build on our long tradition of research excellence while continuing to foster a collaborative, supportive environment where faculty, staff, and students can thrive.”

In 2024, Buchan was elected a Fellow of the American Association for the Advancement of Science (AAAS), a recognition by her peers of extraordinary achievements. Her studies into the physiology and ecology of marine microbes provides insights that could lead to solutions for dealing with issues ranging from antibiotic resistance to breaking down plastic and other waste in the environment.

Buchan also is an elected fellow of the American Society of Microbiology and her honors include an SEC Faculty Achievement Award.

“I’m proud of the collaborative nature of my research program,” Buchan said. “Over the past two decades, my laboratory has worked to understand how marine bacteria and the viruses that infect them shape ocean ecosystems and global biogeochemical cycles.”

“Equally important to me has been mentoring the next generation of scientists,” she said.

Buchan took her first microbiology course as a second-year student and was enthralled, particularly when working in the lab. “What captivated me then (and still does today) is that these microscopic organisms have an enormous influence on the world around us. They drive the Earth’s nutrient cycles, shape the health of ecosystems, influence the wellbeing of plants, animals, and humans, and ultimately make life on our planet possible. I’m still amazed by the remarkable abilities and influence of what is often called the ‘unseen majority.’”

She also saw as an undergraduate student the value of faculty mentors. “My professor invited me to help prepare materials for the teaching laboratory the following year, and soon after, he asked if I’d like to join his research group studying microbes in nearby rivers and streams,” she said. “That experience completely changed the direction of my career.”

Today she values the collaboration and community in UT’s Department of Microbiology. “As department head, I hope to build on that culture while continuing to support innovative research, outstanding teaching, and for students to gain hands-on experience and develop career-ready skills,” Buchan said.

“Microbiology has never been more relevant: from human health to agriculture to climate and environmental sustainability,” she said. “I’m excited about the role our department can play in addressing these challenges while preparing the next generation of scientists.”

by Amy Beth Miller

Wilhelm Named Distinguished Professor

by

no photo placeholder image

Wilhelm Named Distinguished Professor

Profile

Steven Wilhelm, the Kenneth and Blaire Mossman Professor in the UT Department of Microbiology, has been named Distinguished Professor by the Provost. 

Wilhelm’s work in the field of microbiology centers on how microbial communities within the environment interact and how the environment shapes those communities. In the lab, they use tools like DNA and RNA sequencing, metabolomics, and quantitative analyses of DNA/RNA of amplified samples to study microorganisms, such as bacteria and algae. The Wilhelm lab gives graduate students hands-on opportunities in the laboratory and in the field, helping them to be a part of groundbreaking research on the microbiology of lakes and oceans. Currently, the Wilhelm lab is concentrating specifically on virus ecology, toxic cyanobacterial blooms, and developing molecular tools for microbial ecology.

Wilhelm has been awarded numerous recognitions for his work. In 2021, he won the John H Martin Award from the Association for the Sciences of Limnology and Oceanography (ASLO) for his research on the viral shunt. He is also a fellow of the American Academy of Microbiology, a Sustaining Fellow of ASLO, and a Fellow of the Royal Society of Canada.

In 2026 Wilhelm, along with former student Brittany Zepernick (PhD, ‘23) and their collaborator Professor Mike Mckay (U Windsor) were name laureates of the Daylight Academy, receiving the 2026 Daylight Award for their work on how a changing climate influences light usage by Great Lakes algae in the winter.

The honorable title of Distinguished Professor is named by the Provost, recognizing faculty who have contributed to considerable advancement in their fields. These faculty members have cultivated new, transformative knowledge in their area of study, establishing themselves in excellence even internationally. This title recognizes Wilhelm for his achievements as he continues to produce innovative and pioneering research on how microbial communities interact and shape the planet.

by Sloan Docekal

Steven Wilhelm in ‘The Conversation:’ Viruses aren’t all bad: In the ocean, some help fuel the food web – a new study shows how

by

no photo placeholder image

Steven Wilhelm in ‘The Conversation:’ Viruses aren’t all bad: In the ocean, some help fuel the food web – a new study shows how

Profile
A research ship sails in the Atlantic Ocean, where scientists are studying the roles of marine viruses. SW Wilhelm
Steven Wilhelm, University of Tennessee and Joshua Weitz, University of Maryland

Virus. The word evokes images of illness and fears of outbreaks. Yet, in the oceans, not all viruses are bad news.

Some play a helpful, even critical, role in sustaining marine life.

In a new study, we and an international team of scientists examined the behavior of marine viruses in a large band of oxygen-rich water just under the surface of the Atlantic Ocean. What we discovered there – and its role in the food web – shows marine viruses in a new light.

Studying something so tiny

Viruses are incredibly small, typically no more than tens of nanometers in diameter, nearly a hundred times smaller than a bacterium and more than a thousand times smaller than the width of a strand of hair.

In fact, viruses are so small that they cannot be seen using conventional microscopes.

Decades ago, scientists thought that marine viruses were neither abundant nor ecologically relevant, despite the clear relevance of viruses to humans, plants and animals.

Then, advances in the use of transmission electron microscopes in the late 1980s changed everything. Scientists were able to examine sea water at a very high magnification and saw tiny, circular objects containing DNA. These were viruses, and there were tens of millions of them per milliliter of water – tens of thousands of times greater than had been estimated in the past.

A theory for how viruses feed the marine world

Most marine viruses infect the cells of microorganisms – the bacteria and algae that serve as the base of the ocean food web and are responsible for about half the oxygen generated on the planet.

By the late 1990s, scientists realized that virus activity was likely shaping how carbon and nutrients cycled through ocean systems. We hypothesized, in what’s known as the viral shunt model, that the marine viruses break open the cells of microorganisms and release their carbon and nutrients into the water.

This process could increase the amount of nutrients reaching marine phytoplankton. Phytoplankton provide food for krill and fish, which in turn feed larger marine life across the oceans. That would mean viruses are essential to a food web that drives a vast global fisheries and aquaculture industry producing nearly 200 million metric tons of seafood.

Watching viruses in action

In the new study in the journal Nature Communications led by biologists Naomi Gilbert and Daniel Muratore, our international team demonstrated the viral shunt in action.

The team took samples from a meters-thick band of oxygen that spreads for hundreds of miles across the subtropical Atlantic Ocean. In this region, part of the Sargasso Sea, single-celled cyanobacteria known as Prochlorococcus dominate marine photosynthesis with nearly 50,000 to upwards of 100,000 cells in every milliliter of seawater. These Prochlorococcus can be infected by viruses.

What are Prochlorococcus? Science Magazine.

By sequencing community RNA – molecules that carry genetic instructions within cells – our team was able to look at what nearly all viruses and their hosts were trying to do at once.

We found that the rate of virus infection in this oxygen-rich band of the ocean is about four times higher than in other parts of the surrounding ocean, where cyanobacteria don’t reproduce as quickly. And we observed viruses causing massive infections in Prochlorococcus.

The viruses were attacking cells and spilling organic matter, which bacteria were taking up and using to fuel new growth. The bacteria respired away the carbon and released nitrogen as ammonium. And this nitrogen appears to have been stimulating photosynthesis and the growth of more Prochlorococcus cells, resulting in greater production that generated the ribbon of oxygen.

The viral infection was having an ecosystem-scale impact.

Scientists aboard a research vessel prepare a large device with many tubes for collecting samples once lowered into the ocean.
Scientists aboard a National Science Foundation research expedition in the open Atlantic in 2019 prepare equipment to collect water samples at different depths to analyze the activity of marine viruses. SW Wilhelm

Understanding the microscopic world matters

Viruses can cause acute, chronic and catastrophic effects on human and animal health. But this new research, made possible by an open-ocean expedition supported by the National Science Foundation, adds to a growing range of studies that demonstrate that viruses are central players in how ecosystems function, including by playing a role in storing carbon in the deep oceans.

We are living on a changing planet. Monitoring and responding to changes in the environment require an understanding of the microbes and mechanisms that drive global processes.

This new study is a reminder of how important it is to explore the microscopic world further – including the life of viruses that shape the fate of microbes and how the Earth system works.The Conversation

Steven Wilhelm, Professor of Microbiology, University of Tennessee and Joshua Weitz, Professor of Biology, University of Maryland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Graduate Student Sarina Mitchell Wins Smokey’s Choice Award

by

no photo placeholder image

Graduate Student Sarina Mitchell Wins Smokey’s Choice Award

Profile

Microbiology graduate student Sarina Mitchell attended the Lab Safety Culture Awards Dinner on December 11, 2025 and was awarded the Smokey’s Choice Award for demonstrating excellent safety culture while working in her lab. The award was selected by the voting team of the Lab Safety Culture Awards subcommittee.