Rising Research—Trained to Fight

By Leanne Low, Ph.D., Visiting Postdoctoral Research Fellow in the Laboratory of Malaria and Vector Research

Apollo Stacy, Ph.D. headshot

Apollo Stacy, Ph.D.


Apollo Stacy, Ph.D.


The “Rising Research” series aims to elevate the research conducted by NIAID intramural research fellows by featuring their work and stepping behind the bench to get to know the early-stage scientists who drive the research. The first article in the series summarizes the recent Cell paper by Apollo Stacy, Ph.D.

Apollo is an NIAID postdoctoral research fellow in the NIAID Laboratory of Host Immunity and Microbiome and a recipient of the Postdoctoral Research Associate Training (PRAT) Fellowship. His recent research paper published in Cell improves our understanding of the role the microbiota has in our resistance to infectious invaders.

“Don’t hide in the lab, especially at the NIH; there are so many different resources and so many different people who really want to help you...push your PI to push you to think about your future.” — Apollo Stacy, Ph.D.

Our body is host to trillions of microorganisms, a dynamic collection of bacteria and viruses known as our microbiota. We commonly think bacteria and viruses cause disease, not help defend against them, but in fact this defense phenomenon is known as “colonization resistance.” Apollo Stacy, Ph.D., a fourth year NIAID postdoctoral fellow, and his colleagues demonstrate that the microbiota can “remember” pathogens that they have previously been exposed to — dubbed “metaorganism memory” or “microbiota training” — which makes the microbiota even more equipped to fight new pathogens.

“We can give the microbiota certain things that enhance their training,” says Apollo. One of those enhancers, called taurine, is made naturally by the liver and is present in our bile acids. Taurine may sound familiar, as it is present in many energy drinks. In mice, microbes that thrive on taurine were enriched after infection. Apollo further explained, “we’re able to co-opt [taurine] into a metabolite-based therapy, where we don’t require the initial infection, but we can just give mice that nutrient.” Taurine-fed mice showed enhanced resistance to pathogens similar to mice that had received an initial infection instead. In addition, the enriched taurine-using microbes converted taurine into hydrogen sulfide, a “bad bacteria” fighting agent. Subsequently, when faced with a new infection, the trained microbiota knew what to do and used the available taurine. 

In future work, this model could be used to find other training agents that can help our microbiota fight infection and ultimately reduce or replace our reliance on antibiotics, which harm our microbiota and become less effective as bacteria develop resistance. Further studies on the human microbiota could prove this model as an effective way to understand our microbiota and its adaptive nature. “What we’ve thought about in the future is taking fecal samples from human donors and trying to recapitulate our findings in a test tube with some actual human microbiota,” stated Apollo.

Apollo credits much of his research success to his principal investigator, Yasmine Belkaid, Ph.D. “Yasmine has created an environment within her lab to promote the success of her postdocs and her trainees. She has a lot of standing collaborations with investigators across NIH, not just within NIAID, that I was able to benefit from, which was fantastic.” In addition to a great lab environment, which Stacy also emphasized as having people with diverse skill sets, he outlined the many seminars offered by Scientific Interest Groups, core facilities, and the NIH Office of Training and Education (OITE) as being helpful towards increasing his knowledge and facilitating his research. 

When asked to give advice to other postdocs, Apollo strongly suggested the following: “Don’t hide in the lab, especially at the NIH; there are so many different resources and so many different people who really want to help you…push your PI to push you to think about your future.” 

See A Stacy et al. Infection trains the host for microbiota-enhanced resistance to pathogens. Cell (2021), DOI: 10.1016/j.cell.2020.12.011 (2021)
Learn more about postdoctoral research training opportunities at NIAID.
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