Abstract
BackgroundAllergic rhinitis is an inflammatory disease of the upper airway mucosa that also affects leukocytes in bone marrow and peripheral blood. Toll-like receptor 9 (TLR9) is a receptor for unmethylated CpG dinucleotides found in bacterial and viral DNA. The present study was designed to examine the expression of TLR9 in the nasal mucosa and in leukocytes derived from different cellular compartments during symptomatic allergic rhinitis.MethodsThe study was based on 32 patients with seasonal allergic rhinitis and 18 healthy subjects, serving as controls. Nasal biopsies were obtained before and after allergen challenge. Bone marrow, peripheral blood and nasal lavage fluid were sampled outside and during pollen season. The expression of TLR9 in tissues and cells was analyzed using immunohistochemistry and flow cytometry, respectively.ResultsTLR9 was found in several cell types in the nasal mucosa and in different leukocyte subpopulations derived from bone marrow, peripheral blood and nasal lavage fluid. The leukocyte expression was generally higher in bone marrow than in peripheral blood, and not affected by symptomatic allergic rhinitis.ConclusionThe widespread expression of TLR9 in the nasal mucosa along with its rich representation in leukocytes in different compartments, demonstrate the possibility for cells involved in allergic airway inflammation to directly interact with bacterial and viral DNA.
Highlights
Allergic rhinitis is an inflammatory disease of the upper airway mucosa that affects leukocytes in bone marrow and peripheral blood
Ten different Toll-like receptors (TLRs) have been described in humans and Toll-like receptor 9 (TLR9) is the receptor for unmethylated CpG dinucleotides, found in bacterial and viral but not in human DNA [13]
Symptom and rhinoscopy scores Patients challenged with allergen reported augmented nasal symptoms
Summary
Allergic rhinitis is an inflammatory disease of the upper airway mucosa that affects leukocytes in bone marrow and peripheral blood. Toll-like receptor 9 (TLR9) is a receptor for unmethylated CpG dinucleotides found in bacterial and viral DNA. The present study was designed to examine the expression of TLR9 in the nasal mucosa and in leukocytes derived from different cellular compartments during symptomatic allergic rhinitis. Allergic rhinitis is an inflammatory disorder of the mucosa in the upper airways with infiltration of inflammatory cells like neutrophils, eosinophils, basophils and mast cells [1]. Ten different TLRs have been described in humans and TLR9 is the receptor for unmethylated CpG dinucleotides, found in bacterial and viral but not in human DNA [13]. TLR9 has been found on leukocytes like monocytes/ macrophages, B cells and neutrophils as well as in dendritic cells [16,17]
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