Selene Meza-Perez, M.D.

Selene Meza-Perez, Ph.D., instructor in the Division of Immunology and Rheumatology at the UAB Heersink School of Medicine, has been named the latest recipient of the school's Featured Discovery award. This recognition celebrates notable research contributions made by faculty and highlights the impact of their scientific advancements.

The study, titled “Proteobacteria impair anti-tumor immunity in the omentum by consuming arginine,” was recently published in Cell Host & Microbe and explores the complex relationship between gut bacteria and immune responses, particularly how certain bacteria can hinder the body’s natural ability to fight tumors.

“Nobody was studying how nutrients consumed by gut bacteria were impacting immune responses, much less in the omentum,” said Meza-Perez. “Although it was challenging, I applied this new idea to the research model I was developing.”

The study reveals how specific types of bacteria, such as Proteobacteria, consume a vital nutrient called arginine, a compound necessary for activating immune cells that could otherwise target and eliminate tumors. Here’s how it works:

The gut microbiota, bacteria that reside in the intestines, produce various metabolites that affect the body’s immune system. When Proteobacteria are present, they consume arginine in the omentum, a layer of fat near the stomach, which weakens the immune system’s response against tumors in that area. In mice with normal levels of these bacteria, tumors grew unchecked due to an increase in regulatory T cells (Tregs), which suppress the immune response.

However, in mice treated with antibiotics or raised in a germ-free environment (lacking Proteobacteria), immune cells called CD8+ T cells were more effective in fighting tumors. Without the Proteobacteria to consume arginine, higher levels of this nutrient were available, which in turn reduced the suppressive power of Tregs, allowing the CD8+ T cells to attack and shrink the tumors.

The study also demonstrated that adding arginine supplements had a similar effect, enhancing CD8+ T cell function and reducing tumor growth.

Meza-Perez’s findings suggest that targeting arginine consumption by Proteobacteria could be a promising approach to boost the immune system’s ability to fight cancer, especially in visceral adipose tissue.

The Heersink communications team met with Meza-Perez to gain insights into the study and help raise awareness about both the research and the Heersink School of Medicine. 

Q: What compelled you to pursue this research?

I have always been interested in the influence of microbiome on the immune system; thus, I wanted to apply it to the omentum because it is linked to gut circulation and is important for cancer metastasis still is not a common tissue to study much less under microbiota approach.

Q: What was your most unexpected finding?

Different bacteria produce similar outcomes using distinctive immune cell mechanisms. For example, we saw tumor rejection using two different antibiotic treatments that affect two different immune cells.

Q: How do you feel your research will impact the science community?

I think it will give a new perspective on how microbiota controls the immune system. We (all scientists) sometimes tend to focus too much on a single idea for too long. In this case, the assumption that only microbiota produced metabolites have an effect, but to produce, you need to consume, and that gap hasn’t been fully explored.

Q: What is your research’s relevance to human disease?

I would say the relevance lies in the fact that we can now look beyond bacteria composition in cancer outcomes and in something more targeted and comprehensive. Linking gut bacteria, metabolites, and immune cell signatures can aid the regular screening for diagnosis and therapy in cancer patients with metastasis to the omentum.

Q: When did you know you had an important discovery?

When I found that I had the same results on Tregs and tumor outcome using different tumor models and different treatments and that this effect happens only in the omentum and not in other adipose tissue or systemically.