What You Need to Know

Discover how iron could be influencing your allergic reactions and learn what you can do about it.

Scientists have uncovered an unexpected role for iron in triggering allergic airway inflammation, revealing a previously unknown biological pathway that could pave the way for new treatments for asthma and other allergic diseases. ()

The study, published in the journal Cell, found that common environmental allergens such as pollen, house dust mites, and fungal proteins increase iron levels inside airway cells, setting off a chain of molecular events that leads to inflammation—the hallmark of asthma.

Researchers say blocking this iron-driven pathway significantly reduced airway inflammation in animal studies, raising hopes that therapies targeting iron metabolism could help prevent asthma attacks.

How Allergens Trigger Airway Inflammation

Asthma is a chronic inflammatory disease that causes the airways to become swollen and narrowed, making breathing difficult. Symptoms include wheezing, coughing, chest tightness, and shortness of breath.

When allergens enter the lungs, they first come into contact with airway epithelial cells, which form the protective lining of the respiratory tract. These cells release alarm signals that alert the immune system to potential danger.

One of the most important of these alarm molecules is interleukin-33 (IL-33). Once released, IL-33 activates specialized immune cells called type 2 innate lymphoid cells (ILC2s), triggering inflammation, mucus production, eosinophil infiltration, and tissue damage—all key features of allergic asthma. Although previous studies had shown that a protein called Gasdermin D (GSDMD) helps release IL-33, scientists had not understood how allergens activated this protein.

Researchers Identify Iron as the Missing Link

The new study, led by Prof. Sun Bing from the Center for Excellence in Molecular Cell Science at the Chinese Academy of Sciences and Prof. Liu Xing from the Shanghai Institute of Materia Medica, identified iron as the missing trigger.

The researchers discovered that exposure to allergens rapidly increased the amount of free iron inside airway epithelial cells. Rather than activating GSDMD through the conventional inflammatory pathways, the excess iron directly triggered the protein through an entirely different mechanism. The activated GSDMD then promoted the release of IL-33, initiating the inflammatory response that underlies asthma.

How Iron Activates the Asthma Pathway

To understand the mechanism, researchers used mouse models exposed to papain, an enzyme that mimics allergen exposure, and house dust mites, one of the most common asthma triggers. They observed that lung iron levels rose rapidly after allergen exposure, occurring alongside increased IL-33 release.

Further experiments showed that allergens activate a receptor called Protease-Activated Receptor 1 (PAR1) on the surface of airway cells. Activation of PAR1 initiates a process known as ferritinophagy, in which stored iron is released from ferritin, increasing the amount of free iron available inside the cell.

The researchers found that an iron-transport protein called PCBP2 then delivers this iron directly to GSDMD. Instead of relying on the usual inflammation-related enzymes, the iron triggers a localized chemical reaction that produces highly reactive molecules known as hydroxyl radicals. These molecules activate GSDMD, allowing it to release IL-33 and amplify allergic inflammation.

Blocking Iron Reduced Asthma Symptoms

One of the study’s most significant findings was that reducing iron levels dramatically weakened the inflammatory response. Researchers treated mice with deferiprone (DFP), an iron-chelating drug that removes excess iron from cells.

The treatment significantly reduced several hallmarks of allergic asthma, including:

• Airway inflammation
• Eosinophil infiltration
• Levels of inflammatory proteins IL-5 and IL-13
• Excess mucus production

In contrast, giving mice additional iron made allergic inflammation worse. However, this worsening effect disappeared in mice genetically engineered to lack GSDMD, confirming that iron promotes inflammation primarily through the newly identified iron-GSDMD pathway.

A New Target for Asthma Treatment

The researchers say the discovery identifies an entirely new biological pathway—the iron-GSDMD-IL-33 axis—that drives allergic airway inflammation. They believe several points in this pathway could become future treatment targets, including:

• Blocking the PAR1 receptor that senses allergens
• Preventing the release of free iron from cells
• Targeting the PCBP2 iron transport protein
• Using iron-chelating therapies to reduce excess iron in airway cells
• Developing drugs that interrupt the local iron-driven chemical reactions responsible for activating GSDMD

Unlike many current asthma medications that suppress inflammation after it has already begun, these approaches could potentially stop the inflammatory process much earlier.

What the Findings Mean for People With Asthma

The researchers caution that the findings do not mean people with asthma should reduce their dietary iron or stop taking prescribed iron supplements. Iron remains an essential mineral that supports oxygen transport, energy production, immune function, and many other vital processes.

Instead, the study highlights how local iron metabolism inside airway cells, rather than overall iron intake, influences allergic inflammation. Any future treatments would aim to precisely target iron activity within the lungs without affecting the body’s normal iron levels.

Study Opens New Directions for Future Research

The researchers say the discovery expands scientific understanding of both asthma and iron biology by showing that iron is not simply a nutrient but also an important regulator of immune responses.

The findings suggest that the newly identified iron-GSDMD-IL-33 pathway could play a central role not only in asthma but also in other allergic diseases driven by type 2 immune responses.

Although further studies in humans are needed before new therapies become available, the research provides a promising foundation for developing more targeted treatments that interrupt allergic inflammation at its earliest stages, potentially offering better disease control for millions of people living with asthma.

References:

1. Iron drives protease-independent cleavage of gasdermin D in allergic airway diseases – (https://linkinghub.elsevier.com/retrieve/pii/S0092867426006537)

Source-Medindia