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ABSTRACT 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 CD117 low 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 CD117 low 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.
Wirth et al. (Thu,) studied this question.