Involvement of Dendritic Cells and Th17 Cells in Induced Tertiary Lymphoid Structures in a Chronic Beryllium Disease Mouse Model.

OBJECTIVE: To study airway pathophysiology and the role of dendritic cells (DCs) and IL-17 receptor (IL-17R) signals in a mouse model for CBD. METHODS: Here, we present a CBD mouse model in which mice were exposed to beryllium during three weeks. We also exposed IL-17R-deficient mice and mice in which DCs were depleted. RESULTS: Eight weeks after the initial beryllium exposure, an inflammatory response was detected in the lungs. Mice displayed inflammation of the lower airways that included focal dense infiltrates, granuloma-like foci, and tertiary lymphoid structure (TLS) containing T cells, B cells, and germinal centers. Alveolar cell analysis showed significantly increased numbers of CD4+ T cells expressing IFNγ, IL-17, or both cytokines. The pathogenic role of IL-17R signals was demonstrated in IL-17R-deficient mice, which had strongly reduced lung inflammation and TLS development following beryllium exposure. In CBD mice, pulmonary DC subsets including CD103+ conventional DCs (cDCs), CD11b+ cDCs, and monocyte-derived DCs (moDCs) were also prominently increased. We used diphtheria toxin receptor-mediated targeted cell ablation to conditionally deplete DCs and found that DCs are essential for the maintenance of TLS in CBD. Furthermore, the presence of antinuclear autoantibodies in the serum of CBD mice showed that CBD had characteristics of autoimmune disease. CONCLUSIONS: We generated a translational model of sarcoidosis driven by beryllium and show that DCs and IL-17R signals play a pathophysiological role in CBD development as well as in established CBD in vivo.

An essential role for dendritic cells in human and experimental allergic rhinitis.

BACKGROUND: In allergic rhinitis (AR) CD4(+) T(H)2 lymphocytes control inflammation by secreting T(H)2 cytokines, but little is known about how these cells are activated to cause disease. OBJECTIVE: We sought to study the contribution of antigen-presenting dendritic cells (DCs) in activating T(H)2 cells and controlling allergic inflammation. METHODS: Nasal mucosal biopsy specimens were taken from patients with house dust mite allergy and perennial AR and healthy control subjects. DC numbers were evaluated by using immunohistochemistry. The functional role of DCs was studied in a novel mouse model for AR using BALB/c mice and CD11c-diphtheria toxin (DT) receptor transgenic mice. RESULTS: In symptomatic patients with perennial AR, the number of CD1a(+) and CD11c(+) MHCII(+) DCs was higher in the epithelium and lamina propria of the nasal mucosa compared with that seen in healthy control subjects. In patients with AR, DCs had a more mature (CD86(+)) phenotype and were found in close approximation with T lymphocytes. Similarly, in a mouse model of ovalbumin (OVA)-induced AR, CD11c(+) DCs accumulated in areas of nasal eosinophilic inflammation and clustered with CD4(+) T lymphocytes. CD11c(+) DCs were conditionally depleted during allergen challenge by means of systemic administration of DT to CD11c-diphtheria toxin receptor transgenic mice to address the functional role of DCs in maintaining inflammation. In the absence of CD11c(+) DCs, nasal OVA challenge in OVA-sensitized mice did not induce nasal eosinophilia and did not boost OVA-specific IgE levels or T(H)2 cytokine production in the cervical lymph nodes. Conversely, when OVA-pulsed DCs were administered intranasally to sensitized mice, they strongly enhanced OVA-induced nasal eosinophilia and T(H)2 cytokine production. CONCLUSIONS: These data in human subjects and mice suggest an essential role for nasal DCs in activation of effector T(H)2 function leading to AR. CLINICAL IMPLICATIONS: Nasal DCs play an essential role in AR and therefore constitute a novel target for therapeutic intervention.

Benefit from anti-inflammatory treatment during clinical remission of atopic asthma.

STUDY OBJECTIVES: Subjects with atopic asthma often experience a disappearance of symptoms around puberty. However, airway inflammation and remodeling may persist. It is unknown whether those findings warrant prolonged anti-inflammatory treatment despite the absence of symptoms. In this study, we investigated whether a short course of combined anti-inflammatory treatment would, also in this specific patient population, diminish airway inflammation and/or remodeling. DESIGN: A double-blind, randomized placebo-controlled trial was conducted in 28 asymptomatic subjects with a history of atopic asthma, with established bronchial hyperresponsiveness to methacholine (MCh) as non-invasive indicator of ongoing airway pathology. INTERVENTIONS: Intervention consisted of the salmeterol/fluticasone propionate combination (SFC) product (50/250 microg bid via the Diskus inhaler) or placebo for 3 months. MEASUREMENTS: The change in lung function (FEV1), bronchial response to MCh and adenosine monophosphate (AMP), the fraction of nitric oxide in exhaled air (FENO) and quality of life (QOL) scores were measured. Also, bronchial biopsies were taken and cryo sections immunostained for eosinophils (major basic protein, MBP) and mast cells (tryptase and chymase) before and after treatment. The change in reticular basement membrane (RBM) thickness, one of the parameters of airway remodeling, was also determined. RESULTS: SFC treatment improved hyperresponsiveness to MCh (P = 0.014) as well as AMP (P = 0.011), and reduced FENO (P < 0.001) significantly as compared with placebo. Lung function tended to improve (NS). Furthermore, SFC treatment reduced tryptase in the subepithelium of bronchial biopsy specimens (P = 0.01), and slightly reduced RBM thickness (P = 0.05). However, eosinophils in (sub)epithelium were not significantly affected; neither were chymase levels, blood eosinophils or QOL scores. CONCLUSIONS: We found that 3 months of treatment with fluticasone propionate and salmeterol reduced airway hyperresponsiveness, FENO and tryptase density in the airway mucosa as markers of airway inflammation. MBP density in the airway mucosa and QOL were, however, unchanged. The clinical relevance of these findings, especially with respect to the long-term outcome, has not been determined yet.