Influence of sublingual immunotherapy on the expression of Mac-1 integrin in neutrophils from asthmatic children

Allergens Induce the Release of Lactoferrin by Neutrophils from Asthmatic Patients

Background

Despite the evidence that Lactoferrin (Lf) is involved in allergic asthma processes, it is unknown whether neutrophils can be one of the main cellular sources of this key inflammatory mediator directly in response of an IgE mediated stimulus. The present study was undertaken to analyze this question.

Methods

Neutrophils from healthy subjects (n = 34) and neutrophils from allergic asthmatic patients (n = 102) were challenged in vitro with specific allergens to which the patients were sensitized, PAF, or agonist mAbs against IgE-receptors, and the levels of Lf were measured in the culture supernatant. The levels of serum IgE together with the severity of symptoms were also analyzed.

Results

Lf was released into the culture supernatant of neutrophils from allergic asthmatic patients in response to allergens and PAF. This response was highly allergen-specific, and did not happen in neutrophils from healthy donors. Allergen effect was mimicked by Abs against FcεRI and galectin-3 but not by FcεRII. The levels of released Lf correlated well with the levels of serum specific IgE and severity of asthma symptoms. These observations represent a novel view of neutrophils as an important source of Lf in allergic asthma. Importantly, the levels of released Lf by neutrophils could therefore be used to evaluate disease severity in allergic asthmatic patients.

Neutrophils from allergic asthmatic patients produce and release metalloproteinase-9 upon direct exposure to allergens

BACKGROUND

Asthma is characterized by airway inflammation and remodelling in which matrix metalloproteinases (MMPs) play an important role. MMP-9 is the major MMP found in the bronchoalveolar lavage fluids and bronchial biopsies from patients with allergic asthma after allergen challenge, where it correlates with the count of neutrophils and macrophages. However, the cellular sources of MMP-9 in this inflammatory condition have not yet been clearly identified. This work was undertaken to analyse whether neutrophils may be a source of MMP-9 in the allergic asthma condition upon allergen challenge.

METHODS

Neutrophils from allergic asthmatic patients were in vitro stimulated, and the levels of MMP-9 release were measured in the cell culture supernatants using enzyme-linked immunosorbent assay (ELISA) and zymography.

RESULTS

We show that MMP-9 is released by neutrophils, but not by eosinophils from allergic asthmatic patients in response to allergens to which the patients were sensitized. Neutrophils also released MMP-9 in response to anti-IgE Abs, and agonist Abs against FcεRI, FcεRII/CD23 and galectin-3. Inhibitors of transcription and translation, actinomycin D and cycloheximide, partially cancelled this process, suggesting that MMP-9 is also de novo synthesized in response to stimuli. We also show evidence that the MAPKs, p38 and extracellular signal-regulated kinase, as well as the transcription factor NF-κB, are involved, as specific chemical inhibitors of these cell-signalling pathways abolished the anti-IgE/allergen-dependent MMP-9 release.

CONCLUSIONS

These data demonstrate that the exposure of neutrophils to allergens leads to generation of MMP-9, which may then lead to remodelling in asthma.

Allergen immunotherapy decreases LPS-induced NF-κB activation in neutrophils from allergic patients

BACKGROUND

Allergen-specific immunotherapy (IT) is widely used to treat allergic diseases. The molecular mechanisms have not been clarified yet completely. The present work was undertaken to analyze the effect of IT in the activation of NF-κB.

METHODS

Neutrophils from 15 pollen-allergic IT-treated patients, 10 untreated pollen-allergic patients, and 10 healthy donors were in vitro stimulated with LPS. NF-κB activation (p65/p52) was measured in their nuclear extracts by enzyme-linked immunosorbent assay (ELISA). IκBα phosphorylation, NF-κB-repressing factor (NRF) activation, and thromboxane A2 (TXA2 ) and Interleukin-8 (IL-8) release were measured by ELISA.

RESULTS

There was a positive correlation between the score of symptoms and NF-κB activation in human neutrophils. IT significantly decreased NF-κB activation levels in neutrophils compared with neutrophils from untreated patients. IκBα phosphorylation and NRF activation levels were, respectively, significantly lower and higher in neutrophils from IT-treated patients than from untreated patients. IL-8 and TXA2 release were significantly lower in neutrophils from IT-treated patients than from untreated patients.

CONCLUSIONS

IT positive effects are at least in part mediated by the negative regulation of NF-κB activation in human neutrophils. These observations represent a novel view of neutrophils as possible cell target to treat IgE-dependent diseases through NF-κB downmodulation.