Oligomerization and Nitration of the Grass Pollen Allergen Phl p 5 by Ozone, Nitrogen Dioxide, and Peroxynitrite: Reaction Products, Kinetics, and Health Effects.

The allergenic and inflammatory potential of proteins can be enhanced by chemical modification upon exposure to atmospheric or physiological oxidants. The molecular mechanisms and kinetics of such modifications, however, have not yet been fully resolved. We investigated the oligomerization and nitration of the grass pollen allergen Phl p 5 by ozone (O3), nitrogen dioxide (NO2), and peroxynitrite (ONOO-). Within several hours of exposure to atmospherically relevant concentration levels of O3 and NO2, up to 50% of Phl p 5 were converted into protein oligomers, likely by formation of dityrosine cross-links. Assuming that tyrosine residues are the preferential site of nitration, up to 10% of the 12 tyrosine residues per protein monomer were nitrated. For the reaction with peroxynitrite, the largest oligomer mass fractions (up to 50%) were found for equimolar concentrations of peroxynitrite over tyrosine residues. With excess peroxynitrite, the nitration degrees increased up to 40% whereas the oligomer mass fractions decreased to 20%. Our results suggest that protein oligomerization and nitration are competing processes, which is consistent with a two-step mechanism involving a reactive oxygen intermediate (ROI), as observed for other proteins. The modified proteins can promote pro-inflammatory cellular signaling that may contribute to chronic inflammation and allergies in response to air pollution.

Cinnamon extract inhibits allergen-specific immune responses in human and murine allergy models.

BACKGROUND: Ceylon cinnamon has been shown to possess anti-inflammatory properties in many diseases including allergic inflammation. OBJECTIVE: The aim of this study was to analyse in more detail the effects of cinnamon extract (CE) and its major compounds p-cymene and trans-cinnamaldehyde (CA) on allergen-specific immune responses in vitro and in vivo. METHODS: Therefore, monocyte-derived mature dendritic cells (DC) from grass or birch pollen allergic donors were pulsed with the respective allergen in the presence or absence of CE, p-cymene, CA or the solvent ethanol and co-cultured with autologous CD4+ T cells. Furthermore, basophil activation test was performed with or without CE or ethanol treatment. For the in vivo experiments, BALB/c mice were immunized with ovalbumin (OVA) and orally treated with CE or ethanol. RESULTS: Addition of CE, p-cymene or CA, but not ethanol significantly inhibited DC maturation and subsequent allergen-specific T cell proliferation as well as Th1 and Th2 cytokine production. Sulphidoleukotriene release and CD63 expression by basophils were also significantly diminished after addition of CE. In vivo, treatment of OVA-sensitized mice with CE led to a significant shift from OVA-specific IgE towards IgG2a production and to a strong inhibition of OVA-specific proliferation. Moreover, airway inflammation as well as anaphylaxis after intranasal or systemic allergen challenge was significantly reduced in CE-treated mice. Furthermore, topical application of CE prevented calcipotriol-induced atopic dermatitis-like inflammation in these mice. CONCLUSIONS AND CLINICAL RELEVANCE: Taken together, our data indicate that the anti-inflammatory effect of cinnamon might be exploited for treatment of allergic inflammation, which needs to be further investigated.

Anti-inflammatory effects of cinnamon extract and identification of active compounds influencing the TLR2 and TLR4 signaling pathways.

PURPOSE: Inflammatory processes are involved in many diseases. The bark of Cinnamomum verum and its extracts are well known for anti-inflammatory effects, but the underlying active compounds and chemical mechanisms are not yet fully identified. The objective of this study was to elucidate how cinnamon extract, specifically active compounds, and their combinations influence the signaling pathways of inflammation, especially through toll-like receptors TLR2 and TLR4. METHODS: Bioassay-guided fractionation was performed for standard ethanolic cinnamon extract using high performance liquid chromatography followed by compound identification in the determined active fractions by high-resolution mass spectrometry and gas chromatography-mass spectrometry. THP-1 monocytes were pre-incubated with cinnamon extract, cinnamon fractions or its compounds and stimulated with lipopolysaccharides (LPS), followed by determination of interleukin 8 (IL-8) secretion, and phosphorylation of protein kinase B (Akt), nuclear factor (NF)-κB inhibitor alpha (IκBα) and p38. Furthermore, testing was performed in stimulated HEK-TLR2 and HEK-TLR4 reporter cells for direct receptor agonistic effects. RESULTS: Among the identified compounds, trans-cinnamaldehyde and p-cymene significantly reduced the LPS-dependent IL-8 secretion in THP-1 monocytes. Synergistic anti-inflammatory effects were observed for combinations of trans-cinnamaldehyde with p-cymene, cinnamyl alcohol or cinnamic acid. Moreover, cinnamon extract as well as trans-cinnamaldehyde and p-cymene mitigated the phosphorylation of Akt and IκBα. CONCLUSIONS: Trans-cinnamaldehyde and p-cymene contribute to the strong anti-inflammatory effects of cinnamon extract. Furthermore, our experiments indicate that also synergistic effects among compounds that do not exhibit anti-inflammatory effects themselves might be present to positively influence the beneficial effects of cinnamon bark extract.

Screening of herbal extracts for TLR2- and TLR4-dependent anti-inflammatory effects.

Herbal extracts represent an ample source of natural compounds, with potential to be used in improving human health. There is a growing interest in using natural extracts as possible new treatment strategies for inflammatory diseases. We therefore aimed at identifying herbal extracts that affect inflammatory signaling pathways through toll-like receptors (TLRs), TLR2 and TLR4. Ninety-nine ethanolic extracts were screened in THP-1 monocytes and HeLa-TLR4 transfected reporter cells for their effects on stimulated TLR2 and TLR4 signaling pathways. The 28 identified anti-inflammatory extracts were tested in comparative assays of stimulated HEK-TLR2 and HEK-TLR4 transfected reporter cells to differentiate between direct TLR4 antagonistic effects and interference with downstream signaling cascades. Furthermore, the ten most effective anti-inflammatory extracts were tested on their ability to inhibit nuclear factor-κB (NF-κB) translocation in HeLa-TLR4 transfected reporter cell lines and for their ability to repolarize M1-type macrophages. Ethanolic extracts which showed the highest anti-inflammatory potential, up to a complete inhibition of pro-inflammatory cytokine production were Castanea sativa leaves, Cinchona pubescens bark, Cinnamomum verum bark, Salix alba bark, Rheum palmatum root, Alchemilla vulgaris plant, Humulus lupulus cones, Vaccinium myrtillus berries, Curcuma longa root and Arctostaphylos uva-ursi leaves. Moreover, all tested extracts mitigated not only TLR4, but also TLR2 signaling pathways. Seven of them additionally inhibited translocation of NF-κB into the nucleus. Two of the extracts showed impact on repolarization of pro-inflammatory M1-type to anti-inflammatory M2-type macrophages. Several promising anti-inflammatory herbal extracts were identified in this study, including extracts with previously unknown influence on key TLR signaling pathways and macrophage repolarization, serving as a basis for novel lead compound identification.

Molecular mechanisms underpinning laser printer and photocopier induced symptoms, including chronic fatigue syndrome and respiratory tract hyperresponsiveness: pharmacological treatment with cinnamon and hydrogen.

Emissions of laser printers and photocopiers (LP&P) may be associated with health problems. The aim of this review is to describe the clinical picture that is triggered by exposure to LP&P and the molecular mechanisms underpinning the symptoms. Exposure to LP&P to vulnerable subjects may cause a symptom complex consisting of 1) irritation and hyperresponsiveness of the upper and lower respiratory tract; and 2) chronic fatigue (syndrome, CFS). Symptoms occur within hours after L&P exposure and may last for some days or become chronic with exacerbations following LP&P exposure. Substances that can be found in toners or are generated during the printing process are Silica nanoparticles, Titanium Dioxide nanoparticles, Carbon Black, metals, ozone, volatile organic compounds (VOC), etc. The latter may generate oxidative and nitrosative stress (O&NS), damage-associated molecular patterns molecules, pulmonary and systemic inflammation, and modulate Toll Like Receptor 4 (TRL4)­related mechanisms. It is concluded that LP&P emissions may cause activation of the TLR4 Radical Cycle and thus be associated with the onset of chronic inflammatory and O&NS illnesses, such as CFS, in some vulnerable individuals. Cinnamon, an antagonist of the TLR4 complex, and Hydrogen, a potent antiinflammatory and oxygen radical scavenger, may have efficacy treating LP&P-induced illness.