Study Reveals Persistent Inflammatory Cells in Severe Asthma Patients Post-Treatment

A recent study conducted by researchers at Karolinska Institutet in Sweden has uncovered significant findings regarding the effects of biological drugs on patients with severe asthma. The study, published in the journal *Allergy* on June 26, 2025, indicates that certain inflammatory immune cells persist in the bloodstream even after treatment with biologics, such as mepolizumab and dupilumab, which are commonly prescribed to manage severe asthma symptoms.

According to Dr. Valentyna Yasinska, a consultant in pulmonary medicine at Karolinska University Hospital and a doctoral student at the Karolinska Institutet's Department of Medicine, biological drugs have been instrumental in improving the quality of life for many asthma patients. However, this new research suggests that the underlying inflammatory processes may not be fully addressed by current therapeutic strategies. "They help most patients to keep their symptoms under control, but exactly how these drugs affect the immune system has so far remained unknown," Dr. Yasinska stated.

The study, titled "High-Dimensional Analysis of Type 2 Lymphocyte Dynamics During Mepolizumab or Dupilumab Treatment in Severe Asthma," involved the analysis of blood samples from 40 patients before and during treatment. The findings revealed that instead of decreasing, certain types of immune cells associated with asthma inflammation actually increased during treatment. Dr. Jenny Mjösberg, Professor of Tissue Immunology at the same institution, emphasized the implications of these findings: "This suggests that biologics might not attack the root of the problem, no matter how much they help asthma patients during treatment. Continued treatment might be necessary to keep the disease under control."

The researchers utilized advanced techniques, including flow cytometry and single-cell sequencing, to investigate the properties and functions of the immune cells involved. "We were surprised to find that blood levels of inflammatory cells increased rather than decreased," noted Lorenz Wirth, another doctoral student involved in the study. He further explained that this observation could elucidate why airway inflammation often resurfaces when treatment is reduced or stopped.

Historically, biologics have been prescribed for less than a decade, and there is limited understanding of their long-term effects on immune cell dynamics. The next phase of research aims to analyze samples from patients with an extended treatment history and to examine lung tissue to assess how immune cells behave in the airways.

In light of these findings, experts are calling for a reevaluation of treatment protocols for severe asthma. Dr. Yasinska advocates for ongoing research to develop a more comprehensive understanding of the immunological impacts of biologics. "It is important that we understand the long-term immunological effects of these drugs," she asserted.

The persistence of inflammatory cells could have broader implications for asthma management strategies and may necessitate an adjustment in how clinicians approach treatment. As the field of asthma therapy continues to evolve, these findings highlight the importance of ongoing research to optimize care for patients suffering from this chronic condition. The study serves as a reminder that while biological treatments have brought relief to many, a deeper understanding of their mechanisms is crucial for effective management of severe asthma.