Topic: Biology

Scientists at UC San Francisco have discovered a biological pathway that links the gut's immune response to the brain during parasitic infections. This explains why appetite often disappears when you're sick.

Imagine having a severe stomach illness and suddenly losing your appetite, even after the worst symptoms fade away. This is not just a common experience for people who have had a stomach infection, but also for millions of people worldwide who live with long-term parasitic worm infections. Despite how common it is, scientists have struggled to pinpoint exactly what causes this loss of appetite. Researchers at UC San Francisco have now identified the biological pathway that links the gut's immune response to the brain during a parasitic infection. Their work shows how signals from the immune system can actively reduce the desire to eat.

The study focused on two uncommon cell types found in the gut. Tuft cells act as detectors that sense parasites and initiate immune defenses. Enterochromaffin (EC) cells release chemical signals that stimulate nerve pathways connected to the brain. These EC cells are known to produce sensations such as nausea, pain, and general gut discomfort, but it was unclear whether they directly interact with tuft cells.

The researchers found that tuft cells release acetylcholine, a signaling molecule typically associated with nerve cells, in two separate phases. This helps explain why appetite loss often appears later rather than immediately after infection. At first, tuft cells release a short burst of acetylcholine. As the immune response builds and tuft cells increase in number, they begin producing a slower, sustained release of the same signal.

This discovery may also help explain a range of digestive issues, including food intolerances and irritable bowel syndrome.

Why It Matters

Understanding how our gut responds to infections can lead to new treatments for digestive disorders. This research has implications for millions of people worldwide who live with long-term parasitic worm infections.

Key Facts

• Scientists at UC San Francisco have identified a biological pathway that links the gut's immune response to the brain during parasitic infections.
• Tuft cells in the gut release acetylcholine, a signaling molecule typically associated with nerve cells, in two separate phases.
• The prolonged release of acetylcholine is strong enough to activate EC cells and send signals to the brain.
• This discovery may help explain a range of digestive issues, including food intolerances and irritable bowel syndrome.
• The study was published in Nature on March 25, 2026.

Key Terms

Parasitic infections

Infections caused by parasites such as worms

Implications

Understanding how our gut responds to infections can lead to new treatments for digestive disorders. This research has implications for millions of people worldwide who live with long-term parasitic worm infections.