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DOI: 10.1055/s-0036-1584617
Glycolipids of house dust mites – studying the impact of allergen-lipid association
Introduction: House dust mites (HDM) are important inductors of allergic asthma. HDM and its fecal pellets consist of glycoproteins and a wide range of chemically distinct substances, including lipids, which potentially initiate and/or modulate allergic reactions. Lipids can protect allergens from degradation and enhance their cellular uptake. Several major allergens from different sources bear hydrophobic domains, thus enabling them to interact with lipids.
Methods: In order to examine the role of HDM-derived lipids on the initiation of immune responses, lipid-containing molecules were obtained from Dermatophagoides pteronyssinus (D p) bodies (Greer®) and from D p culture medium (Allergopharma) utilizing chloroform/methanol/water extraction. The organic compounds were further fractionated on silica gel and by HPLC; and chemically characterized by HPTLC, GC and GC/MS. The total organic fraction and the subsequent lipid-containing fractions were tested for biological activity on human PBMC cultures based on the analysis of surface activation markers by Flow cytometry.
Results: With regard to polarity and chemical composition, the analysis of HDM bodies and their feces revealed the presence of a broad spectrum of lipid-containing molecules. Additionally, we developed a multiparametric panel for flow cytometry that allows the detection and analysis of innate-like lipid-reactive lymphocytes (NKT cells, gamma/delta T cells and delta/alpha/beta T cells) present on human PBMC. Ex vivo, HDM-derived lipids demonstrated their capacity to activate innate lipid-reactive lymphocytes, evidenced by their surface up-regulation of the activation markers CD25 and CD69.
Discussion: The full chemical characterization of HDM-derived lipids, and the further analysis of the effectors responses (cytokine release, co-stimulatory signals) induced on innate-like lipid-reactive lymphocytes, together with the co-administration of known HDM allergens with isolated lipids, may provide the rational base to understand the structure-function relationship behind the influence of lipids (as adjuvants) on the modulation of type 2 (allergic) responses towards allergens.