A newly discovered family of lipid molecules called pseudo leukotrienes were found to be significantly elevated in patients with severe asthma.

By Alex Perkins


RT’s Three Key Takeaways:

  1. Discovery of Pseudo Leukotrienes: Researchers identified a new family of radical-induced lipid molecules, called pseudo leukotrienes, that were significantly elevated in patients with severe asthma.
  2. Hidden Inflammatory Mechanism: These molecules activate the same inflammatory pathways as classical leukotrienes and may help explain persistent inflammation and variable responses to existing treatments.
  3. Potential Biomarker and Target: Detectable in urine, pseudo leukotrienes could serve as novel biomarkers for disease severity and treatment monitoring while highlighting oxidative stress as a key driver of severe asthma.


Severe asthma was shown to involve a previously unrecognized wave of inflammatory lipid mediators, offering a potential new biomarker for assessing disease severity and treatment response, according to a study in the Journal of Allergy and Clinical Immunology.

Researchers identified a family of cysteinyl leukotriene-like molecules, termed pseudo leukotrienes, generated through radical-induced lipid oxidation. These compounds were found at markedly higher levels in patients with severe asthma and were shown to activate inflammatory signaling pathways long associated with asthma pathology. 

Although cysteinyl leukotrienes have long been implicated in airway inflammation and bronchoconstriction, their precise sources and mechanisms of action have remained incompletely understood. 

In this study, investigators analyzed urine samples from human participants and lung tissue from mouse models using liquid chromatography–tandem mass spectrometry. Mean urinary concentrations of two pseudo leukotrienes were elevated four- to five-fold in individuals with severe asthma compared with controls (P=0.004 and P=0.0015). When combined, these markers significantly improved discrimination between controls and patients with moderate or severe disease. 

Parallel animal experiments showed that pulmonary pseudo leukotriene concentrations doubled following allergen exposure. In cultured human bronchial epithelial cells, these molecules triggered phosphorylation of extracellular signal-regulated kinase and protein kinase B, key components of inflammatory signaling. These effects were inhibited by cysteinyl leukotriene receptor antagonists, indicating that pseudo leukotrienes act through the same receptor pathways as classical leukotrienes. 

The findings suggested that severe asthma biomarkers derived from lipid oxidation may account for inflammatory activity previously attributed solely to enzymatically produced leukotrienes, potentially explaining the variable clinical efficacy of leukotriene receptor antagonists. 

Clinical Implications 

Rather than simply expanding the list of inflammatory mediators in asthma, the study established pseudo leukotrienes as a previously unrecognized mechanistic link between radical-driven lipid biochemistry and cysteinyl leukotriene receptor–dependent inflammation.  

The authors described these molecules as “unknown unknowns” that may have confounded previous disease models. Because pseudo leukotrienes were detectable in human urine and shared biological activity with classical leukotrienes, they may represent a dominant driver of inflammation in severe disease.  

The work also reframed the asthmatic airway as an environment that favors radical chemistry, characterized by elevated reactive oxygen species, depleted antioxidant proteins, and reduced airway glutathione. Monitoring urinary pseudo leukotrienes could therefore support earlier disease detection, assessment of therapeutic efficacy, and preventative correction of impaired antioxidant defenses before asthma progresses. 

Reference 

Liu SY et al. Radical-induced lipid oxidation produces a torrent of leukotriene-like agonists in severe asthma. J Allergy Clin Immunol. 2026;157(1):99-109.

This article was originally published by EMJ and was made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.