Healthcare (Commonwealth Union) – Many organisms instinctively avoid the scent of harmful pathogens. However, a recent study from the University of California, Berkeley, reveals that the nematode C. elegans also responds to the odor of pathogenic bacteria by preparing its intestinal cells to resist a possible infection.
Just as in humans, the intestines of nematodes are vulnerable to disease-causing bacteria. To defend against these threats, the nematode destroys iron-rich organelles known as mitochondria, which are responsible for generating cellular energy. This action helps safeguard iron, a crucial element for many cellular processes, including the production of ATP (adenosine triphosphate), the body’s main energy source.
The discovery that C. elegans can activate this protective response to microbial odors suggests that other organisms, including mammals, might also have the ability to respond defensively to pathogen scents. Andrew Dillin, the study’s lead author and a professor of molecular and cell biology at UC Berkeley, who is also an investigator at the Howard Hughes Medical Institute (HHMI), pointed out the potential implications.
The lead author asked the question as if there is an actual scent emitted by pathogens that we can detect to aid in fighting off infections. He answered it by stating that they are exploring this in mice. If they can prove that humans can sense pathogens through smell and subsequently protect themselves, it could lead to innovations like a pathogen-deterrent perfume in the future.
So far, this response has only been observed in C. elegans. The discovery was unexpected according to the researchers, given that this nematode is one of the most extensively studied laboratory organisms, with every cell tracked from embryo to death.
Julian Dishart, the study’s lead author and recent UC Berkeley Ph.D. graduate, pointed out that what is new here is that C. elegans seems to prepare for a pathogen even before encountering it. There’s also evidence suggesting that this mitochondrial response might be part of a broader immune reaction triggered just by detecting bacterial odors. Since olfaction is a conserved process in animals for regulating physiology and metabolism, it is quite plausible that smell could have a similar effect in mammals as it does in C. elegans.
This research appeared on the 21st of June in the journal Science Advances.
Dillin is at the forefront of research into how stress affects the nervous system and prompts protective mechanisms in cells. Specifically, he explores how stress triggers the activation of a group of genes that help stabilize proteins produced in the endoplasmic reticulum. This activation, known as the unfolded protein response (UPR), functions as a sort of “first aid kit” for mitochondria.
Mitochondria, which are essential for generating energy by processing nutrients, also play crucial roles in signaling, cell death, and growth.
Dillin has demonstrated that disruptions in the UPR system can contribute to diseases and aging. He has also found that stress experienced by mitochondria in one cell can be transmitted to the mitochondria in other cells throughout the body.
Yet, one crucial aspect remains unresolved: if the nervous system can relay stress through a network of neurons to cells responsible for protein production and metabolism, what environmental factors trigger the nervous system in the first place?
“Our nervous system evolved to pick up on cues from the environment and create homeostasis for the entire organism,” says Dillin. “Julian actually figured out that smell neurons are picking up environmental cues and which types of odorants from the pathogens turn on this response.”
Prior research from Dillin’s lab highlighted the role of smell in mammalian metabolism. They discovered that mice deprived of their sense of smell gained less weight despite consuming the same amount of food as their normal counterparts. Dillin and Dishart hypothesize that the aroma of food might initiate a protective response similar to how the body responds to pathogens, preparing the gut to handle the potential impacts of ingesting foreign substances and converting the food into energy.
