Study Finds Immune System Proteins Drive Aging Through Cell Death and Inflammation

Some of the most significant threats to human health come from tiny invaders like viruses and bacteria. We rely on the innate immune system, our natural defense present from birth, to protect us, especially in youth. However, research from the Stowers Institute for Medical Research shows that this protective system may contribute to aging-related diseases. The study led by Randal Halfmann and published in eLife, uncovers a shared energy source that powers immune responses to pathogens. This discovery could help address inflammation and diseases linked to aging, such as Alzheimer’s, Parkinson’s, and cancer.

The research reveals a process where proteins assemble into three-dimensional puzzle-like structures inside infected cells. These protein puzzles amplify invasion signals and prompt the cells to self-destruct, causing inflammation that limits the spread of infection. Halfmann describes the immune response as “like the striking of a match to produce a flame,” where immune cells must mount a significant, irreversible reaction when they detect even a tiny stimulus, like a single molecule of viral DNA. Specific proteins within these cells act as “death decision makers,” with their assembly triggering cell death—a process that might explain fundamental aspects of aging.

A distinctive feature of these proteins is a “death fold domain” that tightly assembles in a complex manner, rarely by accident. A bacterial or viral component inside a cell serves as the template to initiate this assembly. Alex Rodríguez Gama, study lead author, explains that the proteins are “overpacked” or “supersaturated” in cells, storing energy like a battery to rapidly respond to threats by activating immune signaling and inflammation.

The research team tested this concept in yeast cells by analyzing over 100 human proteins with death fold domains and identified a subset functioning as energy stores. Rodríguez Gama states, “A microscopic signal can tap into the battery’s energy storage to suddenly form a very stable protein assembly and fight infection.” 

However, this defense mechanism has a cost. The protein assemblies sometimes form spontaneously without an infection signal, due to random molecular changes. Halfmann calls this a “Catch 22,” explaining that as we age, these proteins may trigger cell death and inflammation even in the absence of invaders. This process creates a tradeoff, providing immediate immune protection but potentially reducing longevity.

Inflammation protects us from infection but persistent inflammation contributes to chronic diseases. Rodríguez Gama highlights their findings offer insight into how inflammation begins and progresses with age. Halfmann emphasizes that “inflammation is one of the major features of many of the diseases that are presently incurable—Alzheimer’s, Parkinson’s, most of the diseases associated with aging, and some cancers—but it starts within individual cells.”

Finally, Halfmann suggests that reducing or reshaping these proteins to prevent their assembly may block inflammation and slow disease development. While such intervention might raise infection risk, “perhaps some patients would be willing to accept that risk.”