Illustration symbolizing easier breathing for children with RSV, representing the potential of new CHI3L1-targeted treatments.

RSV & Kids: How a Hidden Protein Could Hold the Key to Easier Breathing

Author's portrait.
Avery Sinclair in Health & Wellness December 2025 • 4 min read.

"New research uncovers the critical role of the CHI3L1 protein in respiratory syncytial virus (RSV) infections, offering hope for targeted treatments and easier breathing for children."


Respiratory syncytial virus (RSV) is a common culprit behind bronchiolitis, affecting countless infants and young children each year. While most kids recover without serious complications, RSV can lead to severe lower respiratory tract infections (LRTIs), sometimes requiring hospitalization. Recurrent wheezing and even the development of asthma can be linked to early RSV infections, making prevention and effective treatment crucial.

Current treatments for RSV primarily focus on supportive care – managing symptoms and ensuring adequate hydration and breathing. However, scientists are digging deeper, searching for ways to target the virus and the body's response to it. Understanding how RSV evades the immune system and triggers inflammation is key to developing more effective therapies.

Now, a new study sheds light on a specific protein, CHI3L1, and its significant role in RSV-induced airway inflammation. This research, exploring the connection between CHI3L1 and RSV in both children and a controlled lab setting, offers a promising avenue for future treatments aimed at easing breathing difficulties in young RSV patients.

CHI3L1: The Unexpected Culprit in RSV Airway Inflammation?

Illustration symbolizing easier breathing for children with RSV, representing the potential of new CHI3L1-targeted treatments.

The recent study pinpoints Chitinase 3-like 1 protein (CHI3L1) as a key player in the inflammatory response triggered by RSV. This protein, also known as YKL-40 in humans and breast regression protein [BRP]-39 in mice, has previously been linked to asthma and other chronic inflammatory conditions. However, its role in viral respiratory infections was largely unexplored until now.

Researchers discovered that CHI3L1 significantly contributes to airway inflammation in RSV infections. This conclusion stemmed from several key findings:

  • Elevated CHI3L1 in Children: Children hospitalized with RSV showed significantly higher levels of YKL-40 (the human version of CHI3L1) in their nasal secretions compared to children without RSV. These levels also correlated with the severity of their respiratory symptoms.
  • BRP-39 and RSV in Mice: In a controlled lab setting, mice infected with RSV experienced increased expression of BRP-39 (the mouse version of CHI3L1) in their lungs. Mice lacking BRP-39 (knockout mice) exhibited less airway inflammation and reduced levels of inflammatory Th2 cytokines compared to normal mice.
  • BRP-39's Role in Macrophages: The study revealed that BRP-39 influences the activation of M2 macrophages, a type of immune cell that can contribute to airway inflammation in RSV infections.
  • Blocking CHI3L1: Treating RSV-infected mice with an antibody that neutralizes CHI3L1 resulted in reduced airway inflammation and decreased production of Th2 cytokines.
These results strongly suggest that CHI3L1 exacerbates airway inflammation during RSV infections. By understanding this mechanism, scientists can explore new therapeutic strategies that target CHI3L1 to reduce inflammation and improve breathing in children with RSV.

Hope for Easier Breathing: The Future of RSV Treatment

This research offers a promising new target for treating RSV-related breathing difficulties in children. By focusing on CHI3L1, scientists can develop therapies that directly address the excessive inflammation triggered by the virus. While more research is needed, the potential for targeted treatments that ease breathing and reduce the severity of RSV infections brings hope to families facing this common childhood illness.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

1

What is RSV and why is it a concern for children?

Respiratory syncytial virus (RSV) is a common respiratory virus that frequently causes bronchiolitis in infants and young children. While most children recover, RSV can lead to severe lower respiratory tract infections (LRTIs) requiring hospitalization. RSV infections can also contribute to recurrent wheezing and potentially asthma, highlighting the importance of prevention and effective treatment.

2

How does the CHI3L1 protein relate to RSV infections and breathing difficulties in children?

The CHI3L1 protein, also known as YKL-40 in humans and BRP-39 in mice, plays a crucial role in RSV-induced airway inflammation. Elevated levels of YKL-40 in the nasal secretions of children hospitalized with RSV correlate with more severe respiratory symptoms. In laboratory settings, the absence of BRP-39 in mice led to reduced airway inflammation and fewer inflammatory responses, indicating that CHI3L1 exacerbates inflammation and contributes to breathing difficulties during RSV infections.

3

What specific findings from the research highlight the role of CHI3L1 in RSV infections?

Key findings include: 1) Children hospitalized with RSV have significantly higher levels of YKL-40 in their nasal secretions, correlating with symptom severity; 2) Mice infected with RSV showed increased BRP-39 expression in their lungs; 3) Mice lacking BRP-39 exhibited less airway inflammation and reduced inflammatory responses; and 4) Blocking CHI3L1 with an antibody in mice reduced airway inflammation and cytokine production. These findings collectively point to CHI3L1's role in worsening airway inflammation during RSV.

4

What are the implications of CHI3L1's role in RSV infections for future treatments?

The discovery of CHI3L1's role provides a promising new target for RSV treatments. Therapies targeting CHI3L1 could directly address the excessive inflammation caused by RSV, potentially easing breathing difficulties and reducing the severity of infections in children. This could involve developing antibodies or other interventions to neutralize CHI3L1's effects, leading to improved outcomes for young patients.

5

Besides CHI3L1, what other aspects of RSV infection were discussed that are important to know?

The article also mentions the importance of understanding the body's immune response, specifically how RSV evades it and triggers inflammation. It highlights the current reliance on supportive care for RSV, such as managing symptoms, hydration, and breathing. The study also identified the involvement of M2 macrophages, a type of immune cell, in contributing to airway inflammation in RSV infections. All these aspects are important for understanding the complexity of the disease and designing effective treatments.

Newsletter Subscribe

Subscribe to get the latest articles and insights directly in your inbox.