Eosinophil subtypes in asthmatic patients treated with mepolizumab, omalizumab, and dupilumab

Introduction Two eosinophil subtypes, resident (rEos) and inflammatory (iEos), have been identified, first in mouse and later in asthmatic patients. The effects of different biologics on these subpopulations remain unclear. This study evaluates the impact of mepolizumab, dupilumab, and omalizumab on the proportion of rEos and iEos in asthmatic patients over 52 weeks. Methods We conducted a prospective study with one-year follow-up of 82 patients with severe asthma: 28 were not receiving biologic therapy, 24 were treated with mepolizumab, 20 with dupilumab, and 10 with omalizumab. Clinical variables included ACT, exacerbation history, and lung function. Blood samples underwent flow cytometry to classify eosinophils into (Siglec-8+CD62L lo+CD11b hi) for iEos and (Siglec-8+CD62L hi+CD11b lo) for rEos. IL-5 receptor expression and levels of free IL-5 and eotaxin I/II were also assessed. Results Mepolizumab significantly reduced eosinophil concentrations compared to other groups (p<0.001). Patients without biologics had a high iEos proportion (23.4±13.7%), comparable to the omalizumab and dupilumab groups (31.3±12.8% and 27.6±10.1%). Mepolizumab-treated patients had markedly lower iEos proportions (2.4±4.0%, p<0.001). Stratifying iEos by quartiles, there was a significant relation between the highest quartile and lower FEV1% (−15.6%, 5.5–25.7 IC) and a higher exacerbation rate (OR 2.24, 1.02–4.91 IC). After one year, iEos proportions correlated with higher systemic steroid use in mepolizumab and dupilumab groups. At one-year follow-up, IL-5 levels were higher in omalizumab and dupilumab groups but lower in mepolizumab (p<0.01). Conclusion Biological therapies differentially affect eosinophil subtypes, correlating with lung function and steroid use. Monitoring iEos and rEos may serve as a marker of asthma control.