Cytokine trafficking of IL-9 and IL-13 through TfnRc+ vesicles in activated human eosinophils

Abstract

Eosinophils are granulocytes that are elevated in lung mucosa in approximately half of patients with allergic asthma. These highly granulated cells can synthesize and secrete many cytokines, including IL-9 and IL-13. We hypothesized that IL-9 and IL-13 are found as preformed mediators in crystalloid granules and secreted using distinct trafficking pathways. Human eosinophils were purified from peripheral venous blood, adhered to coverslips, and stimulated with platelet activating factor (PAF). Cells were immunolabeled with antibodies to IL-9 or IL-13 and colocalized with markers for secretory organelles, using CD63 for crystalloid granules and transferrin receptor (TfnRc) for vesicles. Fixed cells were imaged using super-resolution microscopy and quantified by colocalization using Pearson's correlation coefficient. IL-9 immunofluorescence increased in a time-dependent manner to PAF, whereas colocalization of IL-9 and CD63 significantly increased from 0.52 to 0.67 after 5 min PAF. Colocalization of IL-9 with TfnRc significantly increased at 60 min of stimulation with PAF (0.54 at 0 min to 0.60 at 60 min). IL-13 showed lower colocalization with CD63 (0.55) than TfnRc (0.63) in unstimulated cells. Upon PAF stimulation, IL-13 intensity transiently decreased at 5 and 60 min, whereas colocalization of IL-13 with CD63 decreased throughout stimulation to 0.43. While colocalization of IL-13 with TfnRc transiently increased to 0.66 at 5 min PAF, it returned to near baseline levels (0.64) after 15 min PAF. Our results suggest that IL-9 and IL-13 are stored in crystalloid granules as well as endosomal structures, and that IL-9 is primarily trafficked to the cell surface via TfnRc + endosome-like vesicles.

Therapeutic Effect of Renifolin F on Airway Allergy in an Ovalbumin-Induced Asthma Mouse Model In Vivo

“…Therefore, Renifolin F may reduce the levels of total IgE and allergen-specific IgE in serum by inhibiting IL-4 and IL-5. As the main product of Th9 cells, IL-9 is a pleiotropic cytokine and can stimulate the proliferation of activated T cells, promote the proliferation and differentiation of mast cells, increase the production of IgE by B cells, upregulate high-affinity IgE receptors and induce the production of IL-6 [34,35]. Activated IL-13 and IL-9 can promote allergen-induced airway hyperresponsiveness [36][37][38].…”

Eosinophils from A to Z

“…CCL, C-C motif chemokine ligand; CXCL, C-X-C motif chemokine ligand; ECP, eosinophil cationic protein; EDN, eosinophil-derived neurotoxin; EPX, eosinophil peroxidase; FGF, fibroblast growth factor; IL, interleukin; M1, classically-activated macrophages; M2, alternatively-activated macrophages; MBP, major basic protein; MMP, matrix metalloproteinase; PDGF, platelet-derived growth factor; TNFα, tumor necrosis factor α; T reg, regulatory T cells; VEGF, vascular endothelial growth factor. • Mast cells and hematopoietic progenitors proliferation and differentiation • Th2 immune response [190,191] IL-10…”

“…• Secretory granules • B cell IgE production • Myeloid DCs proliferation • Th1 and Th2 immune response control [165,192,193] IL-11 Unknown • B cell differentiation • Inhibition of Th1 differentiation [194,195] IL-12 [126,184,191,197] IL-16 Unknown • CD4 + T cells, eosinophils, monocytes, and DCs recruitment [198] IL-25/IL-17E Unknown • Eosinophil activation • Th2 differentiation by promoting eosinophil antigen uptake (E) Lipid mediators…”

The Enigma of Eosinophil Degranulation

“…A network of cytokines and chemokines has been shown to orchestrate inflammatory processes of allergic reactions through the regulation of IgE responses, bone marrow progenitor cell differentiation and the expression of adhesion molecules [9]. Specifically, several Th2 cytokines, including IL-4 and IL-5, are known to be involved in eosinophilic inflammatory diseases especially asthma [169]. IL-5 and eotaxin-3 have been found to work synergistically in chronic subdural hematomas (CSDH).…”