11 research outputs found
Dendritic cells in asthma: a function beyond sensitization
The aim of this thesis is to characterize the involvement of dendritic cells in the induction and
maintenance of the secondary immune response leading to an eosinophilic airway inflammation as seen in asthma. Special attention was attributed to the mechanisms by which
these cells accumulate in the airways of challenged mice, to their interaction with primed
CD4+ T cells as well as to their functional contribution to primed T cell activation. These
questions were addressed in a well-established murine model of eosinophilic airway
inflammation Balb/c mice were sensitized to OVA by an intratracheal injection of OVA-pulsed bone
marrow-derived DCs. Ten days post-sensitization, mice were challenged with an aerosol of
the same antigen resulting in an eosinophilic airway inflammation as shown by histological
analysis of lungs revealing peribronchial and perivascular inflammatory infiltrates and goblet
cell hyperplasia, increased numbers of eosinophils in bronchoalveolar lavage fluid and Th2
cytokine production by draining lymph nodes of the lung. To determine the role of the dendritic cell in the secondary immune
response to inhaled allergen the following research questions were
addressed in this thesis using a murine model for asthma:
- Does the number of dendritic cells in the airways increase during a
secondary immune response? (Chapter 4)
- Is an intratracheal injection of antigen pulsed dendritic cells sufficient
to induce a secondary immune response in already sensitized mice?
(Chapter 5 en 6)
- Does depletion of dendritic cells in sensitized mice before and during
challenge inhibit the development of an eosinophilic airway
inflammation? (Chapter 5)
- Does the capacity of dendritic cells to provide CDS0/86 costimulation
contribute to the function of dendritic cells in the secondary immune
response? (Chapter 6)
- Do eosinophils play a role as antigen presenting cells during the
secondary immune response? (Chapter 7
Airway eosinophils accumulate in the mediastinal lymph nodes but lack antigen-presenting potential for naive T cells
Asthma is characterized by infiltration of the airway wall with
eosinophils. Although eosinophils are considered to be effector cells,
recent studies have reported their ability to activate primed Th2 cells.
In this study, we investigated whether eosinophils are capable of
presenting Ag to unprimed T cells in draining lymph nodes (DLN) of the
lung and compared this capacity with professional dendritic cells (DC).
During development of eosinophilic airway inflammation in OVA-sensitized
and challenged mice, CCR3(+) eosinophils accumulated in the DLN. To study
their function, eosinophils were isolated from the bronchoalveolar lavage
fluid of mice by sorting on CCR3(+)B220(-)CD3(-)CD11c(dim) low
autofluorescent cells, avoiding contamination with other APCs, and were
intratracheally injected into mice that previously received CFSE-labeled
OVA TCR-transgenic T cells. Eosinophils did not induce divisions of T
cells in the DLN, whereas DC induced on average 3.7 divisions in 45.7% of
T cells. To circumvent the need for Ag processing or migration in vivo,
eosinophils were pulsed with OVA peptide and were still not able to induce
T cell priming in vitro, whereas DC induced vigorous proliferation. This
lack of Ag-presenting ability was explained by the very weak expression of
MHC class II on fresh eosinophils, despite expression of the costimulatory
molecules CD80 and ICAM-1. This investigation does not support any role
for airway eosinophils as APCs to naive T cells, despite their migration
to the DLN at times of allergen exposure. DC are clearly superior in
activating T cells in the DLN of the lung
Effects of endocrine disrupting chemicals on in vitro global DNA methylation and adipocyte differentation
Recent studies suggest that endocrine disrupting chemicals (EDCs) may form a risk factor for obesity by altering energy metabolism through epigenetic gene regulation. The goal of this study is to investigate the effects of a range of EDCs with putative obesogenic properties on global DNA methylation and adipocyte differentiation in vitro. Murine N2A and human SK-N-AS neuroblastoma cells and murine preadipocyte fibroblasts (3T3-L1) were exposed to tributyltin (TBT), diethylstilbestrol (DES), bisphenol A (BPA), 2,3,7,8-tetrachlorodibenzo-[. p]-dioxin (TCDD), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), hexachlorobenzene (HCB), hexabromocyclododecane (HBCD), 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) , perfluorinated octyl acid (PFOA) and perfluorinated octyl sulfonate (PFOS). A modest decrease in global DNA methylation was observed in N2A cells exposed to 10. μM DES, BPA, TCDD, BDE-47, PCB-153 and 1. μM HCB, but no changes were found in the human SK-N-AS cells. We reveal for the first time that BDE-47 increases adipocyte differentiation in a dose-dependent manner (2.5-25. μM). Adipocyte differentiation was also enhanced by TBT (≥10. nM) and BPA (<10. μM) and inhibited by TCDD (≥0.1. nM). The other chemicals showed either modest or no effects on adipocyte differentiation at the concentrations tested (PFOA, PFOS and HBCD at 10. μM; PCB-153, 3.4. μM and HCB, 1. μM). This study demonstrates that selected EDCs can induce functional changes in murine adipocyte differentiation in vitro which are accompanied by decreased global DNA methylation. © 2013 Elsevier Ltd
Supplementary Material for: Birch Pollen Immunotherapy in Mice: Inhibition of Th2 Inflammation Is Not Sufficient to Decrease Airway Hyper-Reactivity
<b><i>Background:</i></b> Suppression of Th2 cytokine production by allergen-specific Th2 cells is considered to be critical for the suppression of allergic symptoms by subcutaneous immunotherapy. The aim of this study was to develop a mouse model for birch pollen (BP) immunotherapy to elucidate the underlying mechanisms that contribute to the improvement of clinical symptoms. <b><i>Methods:</i></b> Mice with BP-induced allergic airway inflammation received weekly subcutaneous immunotherapy (SCIT) injections with BP extract (BPE) adsorbed to alum. The effect of an increasing dose of BPE adsorbed to a fixed concentration of alum on the suppression of airway inflammation and airway hyper-responsiveness (AHR) was determined. After 2, 4, 6 or 8 immunotherapy injections, the mice were rechallenged with the same allergen and all hallmarks of allergic asthma were evaluated. <b><i>Results:</i></b> Suppression of the immunological parameters by immunotherapy was dependent on the BPE dose. Two injections were sufficient to suppress IL-4, IL-5, IL-13, IL-10 and IFN-G production, eosinophil recruitment and peribronchial inflammatory infiltrates. BP-specific immunoglobulins were upregulated, but this was not sufficient to reduce AHR. Eight injections were needed to suppress AHR. The gradual reduction in AHR was inversely associated with the increase of BP IgG2a. <b><i>Conclusions:</i></b> BP SCIT induces an early suppression of Th2-mediated eosinophilic airway inflammation, but AHR is only effectively reduced after continued SCIT conceivably by allowing IgG2a antibody titres to build up. i 2014 S. Karger AG, Base
Allergen-induced accumulation of airway dendritic cells is supported by an increase in CD31(hi)Ly-6C(neg) bone marrow precursors in a mouse model of asthma
Airway dendritic cells (DCs) are held responsible for inducing
sensitization to inhaled antigen, leading to eosinophilic airway
inflammation, typical of asthma. However, less information is available
about the role of these cells in ongoing inflammation. In a mouse model of
asthma, sensitization to ovalbumin (OVA) was induced by intratracheal
injection of myeloid OVA-pulsed DCs. Upon OVA aerosol challenge and
induction of eosinophilic airway inflammation in sensitized mice, there
was a time-dependent and almost 100-fold increase in the number of
MHCII(+) CD11b(+) CD11c(+) endogenous airway DCs as well as CD11b(+) blood
DCs. The mechanism of this increase was studied. Adoptive transfer
experiments demonstrated that accumulation of airway DCs was not due to
reduced migration to the mediastinal lymph nodes. Rather, the massive
increase in airway and lymph node DCs was supported by an almost 3-fold
expansion of myeloid CD31(hi)Ly-6C(neg) hematopoietic precursor cells in
the bone marrow (BM). There was no change in any of the other 5
populations revealed by CD31/Ly-6C staining. When these CD31(hi)Ly-6C(neg)
BM precursors were sorted and grown in granulocyte
macrophage-colony-stimulating factor, they differentiated into MHCII(+)
CD11c(+) DCs. The same CD31(hi)Ly-6C(neg) precursors also expressed the
eotaxin receptor CCR3 and differentiated into eosinophils when grown in
interleukin 5. Serum levels of eotaxin were doubled in mice with
inflammation. These findings in an animal model of asthma suggest that the
BM increases its output of myeloid precursors to meet the enhanced demand
for DCs and eosinophils in inflamed airways
Eosinophils: Biological properties and role in health and disease
Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of diverse inflammatory responses, as well as modulators of innate and adaptive immunity. In this review, the biology of eosinophils is summarized, focusing on transcriptional regulation of eosinophil differentiation, characterization of the growing properties of eosinophil granule proteins, surface proteins and pleiotropic mediators, and molecular mechanisms of eosinophil degranulation. New views on the role of eosinophils in homeostatic function are examined, including developmental biology and innate and adaptive immunity (as well as their interaction with mast cells and T cells) and their proposed role in disease processes including infections, asthma, and gastrointestinal disorders. Finally, strategies for targeted therapeutic intervention in eosinophil-mediated mucosal diseases are conceptualized