High-Dimensional Analysis of Type 2 Lymphocyte Dynamics During Mepolizumab Treatment in Severe Asthma

Background Although the type 2 biologics mepolizumab and dupilumab show clinical efficacy in severe asthma, their influence on circulating lymphocytes is largely unknown. Here, we studied their impact on type 2 lymphocytes in severe asthma. Methods We performed high-parameter flow cytometry analysis of peripheral blood mononuclear cells from 40 patients with severe asthma before, and after 4 and 12 months of mepolizumab (n = 33) or dupilumab (n = 7) treatment, focusing on type 2 lymphocytes. Additionally, we performed single-cell RNA sequencing (scRNA-seq) (n = 3) and stimulation experiments of type 2 lymphocytes (n = 3) to explore transcriptional and functional changes associated with mepolizumab treatment. Results Mepolizumab treatment increased circulating type 2 innate lymphoid cell (ILC2), type 2 T helper (Th2) and type 2 cytotoxic (Tc2) cell frequencies, skewing ILC2 towards a CD117low signature with high CD62L expression, and Th2/Tc2 cells towards a CD45RA−CD62L+ central memory phenotype. Dupilumab-treated patients also showed increased frequencies of total ILC2 and CD117low ILC2. Mepolizumab treatment reduced the expression of tissue homing receptors CXCR4 in ILC2, and GPR183 in ILC2, Th2, and Tc2 cells while enhancing their type 2 cytokine producing capability in response to alarmins. Conclusion Mepolizumab increases the frequencies of circulating ILC2, Th2, and Tc2 cells, with reduced tissue homing receptor expression but increased type 2 cytokine production potential. This reveals a potentially new mechanism for how mepolizumab reduces airway inflammation by re-directing trafficking of inflammatory type 2 lymphocytes away from airway-homing, with implications for the possibility of achieving biologics-free remission in asthma. Biobanked PBMCs from 3 severe asthma patients at baseline and after 1 year of mepolizumab treatment were thawed and FACS-sorted for ILC2, Th2 and Tc2 cells. Subsequently, single cell RNA-sequencing was performed. *** Due to patient confidentiality concerns, Swedish law does not allow the raw data to be hosted outside of Sweden; contact submitter for more details. *** Flow cytometry data referred to in the abstract is available at: https://doi.org/10.5281/zenodo.15921459 *************************************************************** Due to patient-privacy concerns, raw data files cannot be made available. ***************************************************************