Scientists Solve a 30-Year Mystery About How the Body Controls Inflammation

For decades, one of the more frustrating puzzles in inflammation research was a molecule that researchers could clearly observe doing important things in the body, but whose origins they could not fully trace. The molecule, called 5-oxo-eicosatetraenoic acid (5-oxoETE), is known to be a potent attractor of white blood cells, particularly neutrophils and eosinophils. When tissue is damaged, 5-oxoETE levels rise sharply, and immune cells follow the signal toward the injury site. Scientists could detect it, measure its effects, and block its receptor in experiments. What they could not reliably explain, until now, was which enzyme was responsible for producing it. That gap has been open since the molecule was first characterized in the early 1990s, more than 30 years ago.

A team at Memorial Sloan Kettering Cancer Center has closed it. Their study, published in Nature on October 7, 2026, identifies DHRS7 as an orphan short-chain fatty acid dehydrogenase and reductase enzyme that serves as the central switch in 5-oxoETE signaling. The finding is significant not only because it names the enzyme but because of what the discovery reveals about how the body decides when inflammation is needed and when it is not. The source news release and the paper itself were covered widely in science media through early November 2026 as one of the more consequential basic-science inflammation findings in recent years.

A 30-Year Gap in the Inflammation Circuit

The story of 5-oxoETE starts with how the body senses damage. When cells are stressed or injured, they ramp up oxidative activity as part of a defensive response. This oxidative shift changes the chemical environment inside cells, and cells in that environment begin producing pro-inflammatory signals. 5-oxoETE is one of those signals, produced from arachidonic acid, a fatty acid found in cell membranes. White blood cells carry a receptor called OXER1 that binds 5-oxoETE and responds by migrating toward the signal source. This makes 5-oxoETE a recruiting molecule, a molecular call to arms that tells immune cells where to go.

The long-standing puzzle was about the enzyme responsible for synthesizing 5-oxoETE from its precursor. A well-understood enzymatic step converts arachidonic acid into a compound called 5-HETE, and from there a second enzymatic step was believed to generate 5-oxoETE. That second enzyme was identified more than 30 years ago as a dehydrogenase, but which gene encoded it remained unknown. Researchers looked for the gene through the 1990s and 2000s without a definitive answer. It had become what scientists sometimes call an orphan enzyme pathway: the biochemistry was understood, but the genetic identity was missing, leaving a gap in the molecular picture of how inflammatory signaling is initiated.

The MSK team closed the gap using zebrafish and human cells. Zebrafish are a standard laboratory model for studying inflammation because their skin wounds and gut lining can be observed in real time under a microscope, and their immune system shares the core features of the human one. By systematically testing candidate genes in both models, the team identified DHRS7 as the missing dehydrogenase. When they suppressed DHRS7 in zebrafish wounds, the sharp rise in 5-oxoETE that normally follows injury was blunted. When they introduced DHRS7 into cells lacking the enzyme, 5-oxoETE production resumed. The identification was confirmed in human intestinal cell lines as well, strengthening the case that the discovery applies beyond the fish model.

Not Just an Alarm: The Dual Role of 5-oxoETE

What makes the Nature paper particularly notable is its finding that 5-oxoETE plays a protective role in addition to its inflammatory one. The conventional picture of inflammation-signaling lipids treats them as triggers: they go up, they recruit immune cells, the immune cells do their job, and then other mediators bring the response down. The MSK team found something more complex. When DHRS7 is active, it uses the NADP to NADPH ratio inside the cell as a sensor. At wound sites, where oxidative stress is high and the NADP form dominates, DHRS7 drives 5-oxoETE production, which calls in white blood cells. But in undamaged tissue, where NADPH levels are higher, the same enzyme runs in the opposite direction, consuming 5-oxoETE and keeping its levels low. The enzyme is both the maker and the eraser of the signal, depending on what the cell's internal chemistry is telling it about the surrounding conditions.

This dual function means 5-oxoETE is not simply a switch that turns inflammation on. It is part of a feedback system that reads oxidative state to calibrate how much inflammatory recruitment is appropriate. At genuine injury sites, the signal amplifies and brings in immune cells. In tissue that is not actually damaged, the signal stays quenched. This is a more sophisticated architecture than a simple on and off mechanism, and it helps explain a question that has long interested inflammation researchers: how does the immune system know the difference between damaged tissue that needs attention and healthy tissue that does not?

The team also found that 5-oxoETE supports the structural resilience of epithelial tissue, the cells that line the gut, lungs, and skin. When zebrafish were engineered to lack OXER1, the receptor that 5-oxoETE signals through, those animals developed spontaneous intestinal inflammation even without any infection or injury. Their gut lining showed higher rates of cell death, disrupted barrier function, and signs of microbial infiltration. Mechanistically, the team traced this back to a family of enzymes called NUDIX hydrolases. These enzymes protect the nucleotide building blocks inside cells from oxidative damage, and 5-oxoETE appears to induce their expression. Without that induction, oxidized nucleotides accumulate and cells become more prone to apoptosis, the programmed cell death that breaks down the gut barrier.

What This Means for Chronic Inflammation

The significance of the finding extends beyond explaining normal wound-healing biology. One of the central questions in chronic inflammatory disease is why the immune system stays activated long after a triggering event is gone, or why some people develop persistent low-grade inflammation without an obvious acute injury at all. The DHRS7-5-oxoETE pathway offers a potential partial answer: if the enzyme's ability to quench unnecessary inflammation is compromised, or if the redox balance that it reads is persistently shifted toward the oxidative end, the system might keep generating pro-inflammatory signals even in tissue that is not genuinely damaged.

This is consistent with what is already known about chronic inflammatory conditions and oxidative stress. Metabolic disorders like obesity and type 2 diabetes, cardiovascular disease, and several autoimmune conditions are all characterized by both elevated oxidative stress markers and persistent activation of inflammatory pathways. If DHRS7 serves as a bridge between oxidative state and inflammatory recruitment, then states of chronic oxidative stress could keep 5-oxoETE levels elevated for the same reason a wound site keeps them elevated: the NADP to NADPH ratio is shifted, and DHRS7 keeps generating the signal that calls in immune cells. The system built to respond to genuine damage would then be running chronically in a tissue environment that resembles damage from the inside without a wound on the outside.

The MSK researchers are careful to frame their findings as mechanistic rather than immediately therapeutic. Zebrafish experiments and human cell cultures are early steps, and the gap from identifying a pathway to developing drugs that target it safely is large. OXER1 antagonists and DHRS7 inhibitors are conceivable targets, but they would need to be tested for whether blocking the pathway interferes with normal wound healing and infection defense, since the same system is essential for recruiting white blood cells when they are genuinely needed. That protective role is precisely what makes the pathway interesting from a drug-targeting standpoint: a compound that blocks 5-oxoETE signaling entirely might protect tissue from one type of damage while leaving it vulnerable to another.

Why This Matters for Understanding Your Own Inflammation

Basic-science discoveries like this one take years to translate into clinical tools, but they clarify the biology that makes tracking inflammation useful in the first place. The DHRS7 finding reinforces a picture of inflammation that researchers have been building for decades: the same molecular machinery that protects you from infection can, under different conditions, become a source of persistent low-grade tissue damage. What determines which outcome you get is the balance between pro-inflammatory signaling and the feedback mechanisms that contain and resolve it. When that balance is maintained, inflammation does its job and stops. When it is not, the result is elevated circulating markers like C-reactive protein, IL-6, and others that reflect ongoing immune activity even without an acute infection or injury.

CRP is the most commonly used general-purpose signal of this kind. It is produced by the liver in response to cytokines released during inflammation, and its level in blood, or in saliva with current consumer testing methods, reflects the aggregate output of inflammatory signaling happening across the body. A reading that stays elevated over weeks or months, rather than spiking briefly in response to a cold or minor injury and then returning to baseline, is a signal worth paying attention to and worth discussing with a healthcare provider. It does not by itself tell you which molecular pathway is out of balance, but it confirms that some imbalance exists. Discoveries like the DHRS7-5-oxoETE finding contribute to the science underlying why that signal matters, and they point toward future tests that might eventually identify the specific circuits involved.

For now, the most practical takeaway is a conceptual one. Inflammation is not a simple on or off state. It is a tightly regulated system with multiple feedback loops, and the DHRS7 finding adds detail to one of those loops that was previously uncharacterized. Understanding that the body has these built-in control mechanisms, and that they depend on biochemical states like the NADPH to NADP ratio that are themselves influenced by diet, sleep, exercise, and metabolic health, reinforces why lifestyle factors matter for inflammatory tone. The same conditions that chronically shift the redox balance inside cells are the ones associated with elevated CRP in population studies. The molecular plumbing that the MSK team has now mapped is part of the same system that those markers measure at the aggregate level.

Sources

• Ma Y, Lengyel M, Hui KL, et al. 5-oxoETE links redox control of epithelial damage detection and resilience. Nature, 2026. pubmed.ncbi.nlm.nih.gov/42844471
• Kalyvianaki K, Salampasi EM, Katsoulieris EN, et al. 5-Oxo-ETE/OXER1: A Link between Tumor Cells and Macrophages Leading to Regulation of Migration. Molecules, 2024. pubmed.ncbi.nlm.nih.gov/38202807
• Kalyvianaki K, Drosou I, Notas G, et al. Enhanced OXER1 expression is indispensable for human cancer cell migration. Biochemical and Biophysical Research Communications, 2021. pubmed.ncbi.nlm.nih.gov/34775286
• Memorial Sloan Kettering Cancer Center. Of Mice and Zebrafish: How MSK Scientists Solved a Decades-Old Mystery and Uncovered New Insights About Inflammation. MSK News, 2026. mskcc.org

Frequently Asked Questions

What is 5-oxoETE and what does it do?

5-oxoETE (5-oxo-eicosatetraenoic acid) is a lipid molecule derived from arachidonic acid in cell membranes. It acts as a pro-inflammatory signal, binding to a receptor called OXER1 on white blood cells such as neutrophils and eosinophils and attracting them toward sites of tissue damage. A 2026 Nature study from Memorial Sloan Kettering Cancer Center also found that 5-oxoETE supports the structural resilience of epithelial tissue, meaning it plays a dual role as both an alarm signal and a tissue protector.

What did scientists discover about inflammation in October 2026?

Researchers at Memorial Sloan Kettering Cancer Center published a study in Nature identifying DHRS7, an enzyme that had gone uncharacterized for more than 30 years, as the molecular switch behind 5-oxoETE signaling. The team showed that DHRS7 generates 5-oxoETE in cells under oxidative stress, such as at wound sites, and consumes it in healthy, undamaged tissue. This dual function helps the body calibrate inflammatory responses to match actual tissue damage rather than generating inflammation continuously.

What does this discovery mean for people with chronic inflammation?

The finding suggests that chronic oxidative stress, the kind associated with metabolic conditions, poor sleep, and certain dietary patterns, may keep the DHRS7-5-oxoETE pathway running in a state that resembles an ongoing wound signal even without acute injury. This provides a molecular framework for understanding why chronic low-grade inflammation develops and why it tends to cluster with conditions that elevate oxidative stress markers. It is mechanistic science that is not yet translatable into specific treatments, but it adds precision to the broader picture of how inflammation becomes self-sustaining.

Can tracking CRP at home help monitor inflammation from these kinds of pathways?

CRP is a downstream marker of inflammation, produced by the liver in response to cytokines generated across many inflammatory pathways including, ultimately, those involving 5-oxoETE and similar signals. At-home CRP testing does not identify which specific pathway is active, but it reflects the aggregate level of inflammatory activity in the body. A persistently elevated reading over weeks or months is a general wellness signal worth discussing with a healthcare provider, and tracking it over time helps you see whether lifestyle changes are shifting your baseline in a healthier direction. Sensa is a general wellness product and not a medical diagnostic tool.