Kinetics of TH2 biomarkers in sputum of asthmatics following inhaled allergen

Abstract

BackgroundAllergen-induced late airway response offers important pharmacodynamic targets, including T helper 2 (TH2) biomarkers. However, detection of inflammatory markers has been limited in dithiothreitol-processed sputum.ObjectivesTo test whether allergen-induced TH2 inflammatory markers can be reproducibly quantified by sensitive detection techniques in ultracentrifuged sputum and the effect of fluticasone (FP) on these endpoints.MethodsThirteen allergic asthmatics with dual allergen-induced airway responses, documented during a single-blind placebo run-in period, participated in a double-blind, two-period crossover study. Each period consisted of three consecutive days, separated by ≥3 weeks. Following randomization, subjects inhaled FP (500 µg bid, five doses total) or placebo. On Day 2 in each study period, allergen challenge was performed and airway response measured by forced expiratory volume in 1 sec (FEV1) until 7 h post-challenge. Sputum was induced 24 h pre-allergen and 7 and 24 h post-allergen. Sputum samples were split into two portions: TH2 biomarkers were quantified by Meso Scale multiplex platform following ultracentrifugation, and cell differentials were counted on Giemsa–May-Grünwald-stained cytospins. Allergen-induced changes in inflammatory endpoints were compared between FP and placebo using a mixed model ANCOVA.ResultsInhaled allergen induced dual airway responses in all subjects during both placebo periods with reproducible late asthmatic response (LAR) and increased sputum inflammatory biomarkers (IL-2, IL-4, IL-13, and eotaxin-1) and eosinophil counts. FP effectively blunted both the LAR and the inflammatory biomarkers.ConclusionsCombining novel, sensitive quantification methods with ultracentrifugation allows reproducible quantification of sputum biomarkers following allergen challenge, reversed by FP. This approach allows non-invasive identification of pharmacodynamic targets for anti-asthma therapies.

Proteomic analysis of serum and sputum analytes distinguishes controlled and poorly controlled asthmatics

“…IL‐8 was also expressed at higher concentration in sputum compared to serum, and was further elevated in sputum of poorly controlled compared to controlled asthmatics. Consistent with this, others have reported elevated sputum IL‐8 in asthmatics, including those with chronic refractory asthma, severe eosinophilic asthma, and following inhaled allergen challenge . CCL28 and TFF3, which are markers of mucosal epithelial damage, were also at higher concentration in sputum compared to serum.…”

Erythropoietin exerts direct immunomodulatory effects on the cytokine production by activated human T-lymphocytes

“…Indeed, Epo has been demonstrated to up-regulate antibody (Ab) production [5], facilitate the generation of antigen-specific CD8 + cytotoxic T cells (CTLs) and sustain functional activity of CD4 + Т-helper (Th) cells in patients with chronic renal failure undergoing hemodialysis treatment [6]. Epo-mediated effects are considered to be associated with the up-regulation of dendritic cell differentiation activity and the enhancement of their antigen presentation capacity [4], as well as with the direct anti-apoptotic impact of Epo on T-cells [7] and the stimulation of T-cell-dependent IL-2 production [8]. On the other hand, there is evidence to suggest that Epo possesses intrinsic immunosuppressive activity.…”

Small airway involvement in the late allergic response in asthma

“…We cannot, however, rule out the effect of maintenance therapy on baseline parameters in our study as the majority of the dual responders were on maintenance therapy with low‐dosed ICS. Following allergen challenge, only incomplete bronchoprotection was achieved, while mainly high doses of ICS have been shown to fully protect against the LAR . In addition, all subjects on maintenance ICS treatment were prescribed dry powder inhalers, primarily targeting large airways .…”

“…Following allergen challenge, only incomplete bronchoprotection was achieved, while mainly high doses of ICS have been shown to fully protect against the LAR. 4 In addition, all subjects on maintenance ICS treatment were prescribed dry F I G U R E 3 Impulse oscillometry. R5 (A), R20 (B), X5 (C) and F res (D) in single and dual responders after the allergen challenge.…”

“…3 Subjects with both an EAR and a LAR are called dual responders. During the LAR, there is a T-helper 2-cell response within the airways, characterized by the presence of inflammatory cells and mediators [4][5][6] for at least 24 hours post-challenge, and an allergen-induced bronchial hyperreactivity that can last for several weeks. 2 While the EAR is thought to affect mainly large airways, the LAR is believed to involve the small airways as well.…”