BACKGROUND: Eosinophils develop from CD34(+) progenitors under the influence of IL-5. Atopic asthmatic individuals have increased numbers of mature eosinophils and eosinophil pro-genitors within their bone marrow and bronchial mucosa. We have previously reported that anti-IL-5 monoclonal antibody treatment decreases total bone marrow and bronchial mucosal eosinophil numbers in asthma. OBJECTIVE: Using an anti-IL-5 monoclonal antibody, we examined the role of IL-5 in eosinophil development within the bone marrow and bronchial mucosa in asthma. METHODS:Blood, bone marrow, and airway mucosal biopsy specimens were examined before and after anti-IL-5 (mepolizumab) treatment of asthmatic individuals in a double-blind, placebo-controlled trial. Numbers of mature and immature eosinophils were measured by histologic stain (bone marrow myelocytes, metamyelocytes, and mature eosinophils), flow cytometry (bone marrow and blood CD34(+)/IL-5Ralpha(+) cells), enumeration of bone marrow-derived eosinophil/basophil colony-forming units in methylcellulose culture, and sequential immunohistochemistry and in situ hybridization (bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cells). RESULTS:Mepolizumab decreased mature eosinophil numbers in the bone marrow by 70% (P =.017) in comparison with placebo and decreased numbers of eosinophil myelocytes and metamyelocytes by 37% (P =.006) and 44% (P =.003), respectively. However, mepolizumab had no effect on numbers of blood or bone marrow CD34(+), CD34(+)/IL-5Ralpha(+) cells, or eosinophil/basophil colony-forming units. There was a significant decrease in bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cell numbers in the anti-IL-5 treated group (P =.04). CONCLUSION: These data suggest that anti-IL-5 therapy might induce partial maturational arrest of the eosinophil lineage in the bone marrow. The reduction in airwayCD34(+)/IL-5 mRNA(+) cell numbers suggests that IL-5 might also be required for local tissue eosinophilopoiesis.
RCT Entities:
BACKGROUND: Eosinophils develop from CD34(+) progenitors under the influence of IL-5. Atopic asthmatic individuals have increased numbers of mature eosinophils and eosinophil pro-genitors within their bone marrow and bronchial mucosa. We have previously reported that anti-IL-5 monoclonal antibody treatment decreases total bone marrow and bronchial mucosal eosinophil numbers in asthma. OBJECTIVE: Using an anti-IL-5 monoclonal antibody, we examined the role of IL-5 in eosinophil development within the bone marrow and bronchial mucosa in asthma. METHODS: Blood, bone marrow, and airway mucosal biopsy specimens were examined before and after anti-IL-5 (mepolizumab) treatment of asthmatic individuals in a double-blind, placebo-controlled trial. Numbers of mature and immature eosinophils were measured by histologic stain (bone marrow myelocytes, metamyelocytes, and mature eosinophils), flow cytometry (bone marrow and blood CD34(+)/IL-5Ralpha(+) cells), enumeration of bone marrow-derived eosinophil/basophil colony-forming units in methylcellulose culture, and sequential immunohistochemistry and in situ hybridization (bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cells). RESULTS:Mepolizumab decreased mature eosinophil numbers in the bone marrow by 70% (P =.017) in comparison with placebo and decreased numbers of eosinophil myelocytes and metamyelocytes by 37% (P =.006) and 44% (P =.003), respectively. However, mepolizumab had no effect on numbers of blood or bone marrow CD34(+), CD34(+)/IL-5Ralpha(+) cells, or eosinophil/basophil colony-forming units. There was a significant decrease in bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cell numbers in the anti-IL-5 treated group (P =.04). CONCLUSION: These data suggest that anti-IL-5 therapy might induce partial maturational arrest of the eosinophil lineage in the bone marrow. The reduction in airway CD34(+)/IL-5 mRNA(+) cell numbers suggests that IL-5 might also be required for local tissue eosinophilopoiesis.
Authors: Elizabeth A Kelly; Stephane Esnault; Lin Ying Liu; Michael D Evans; Mats W Johansson; Sameer Mathur; Deane F Mosher; Loren C Denlinger; Nizar N Jarjour Journal: Am J Respir Crit Care Med Date: 2017-12-01 Impact factor: 21.405
Authors: Lennart Greiff; Cecilia Ahlström-Emanuelsson; Ash Bahl; Thomas Bengtsson; Kerstin Dahlström; Jonas Erjefält; Henrik Widegren; Morgan Andersson Journal: Respir Res Date: 2010-02-09