Browsing by Author "Weichenmeier, Ingrid"

BACKGROUND: Clara cell protein (CC16), the main secretory product of bronchiolar Clara cells, plays an important protective role in the respiratory tract against oxidative stress and inflammation. The purpose of the study was to investigate the role of elemental carbon ultrafine particles (EC-UFP)-induced oxidative stress on Clara cells and CC16 in a mouse model of allergic lung inflammation. METHODS: Ovalbumin (OVA)-sensitized mice were exposed to EC-UFP (507 microg/m(3) for 24 h) or filtered air immediately prior to allergen challenge and systemically treated with N-acetylcysteine (NAC) or vehicle prior and during EC-UFP inhalation. CC16 was measured up to one week after allergen challenge in bronchoalveolar lavage fluid (BALF) and in serum. The relative expression of CC16 and TNF-alpha mRNA were measured in lung homogenates. A morphometrical analysis of mucus hypersecretion and electron microscopy served to investigate goblet cell metaplasia and Clara cell morphological alterations. RESULTS: In non sensitized mice EC-UFP inhalation caused alterations in CC16 concentration, both at protein and mRNA level, and induced Clara cell hyperplasia. In sensitized mice, inhalation of EC-UFP prior to OVA challenge caused most significant alterations of BALF and serum CC16 concentration, BALF total protein and TNF-alpha relative expression compared to relevant controls; their Clara cells displayed the strongest morphological alterations and strongest goblet cell metaplasia occurred in the small airways. NAC strongly reduced both functional and morphological alterations of Clara cells. CONCLUSION: Our findings demonstrate that oxidative stress plays an important role in EC-UFP-induced augmentation of functional and morphological alterations of Clara cells in allergic lung inflammation.

Background: Silica (SiO2) nanoparticles (NPs) are widely used in diverse industrial and biomedical applications. Their applicability depends on surface modifications, which can limit potential health problems. Objective: To assess the potential impact of SiO2 NP exposure and NPs chemical modifications in allergic airway inflammation. Methods: Mice were sensitized by five repetitive intraperitoneal injections of ovalburnin/aluminum hydroxide (1 mu g) over 42 days, then intratracheally instilled with plain or modified SiO2 NPs (50 mu g/mouse), and subsequently aerosol challenged for 20 minutes with ovalbumin. One or 5 days later, allergic inflammation was evaluated by cell differentiation of broncho-alveolar lavage fluid, lung function and gene expression and histopathology, as well as electron and confocal microscopy of pulmonary tissue. Results: Plain SiO2 NPs induced proinflammatory and immunomodulatory effects in vivo, highlighted by enhanced infiltration of inflammatory cells in the broncho-alveolar lavage fluid, induction of a pulmonary T helper type 2 (Th2) cytokine pattern, differentiation of type 2 macrophages, and by morphological changes in the lung of sensitized mice. These effects were dramatically attenuated using surface-functionalized NPs with amino and phosphate groups, but not with polyethylene glycol. The role of macrophages in taking up SiO2 NPs was confirmed by flow cytometry, confocal microscopy, and gene expression analysis. Conclusion: Our data suggest that amino and phosphate surface modifications, but not polyethylene glycol (PEG), mitigate the proinflammatory and immunomodulatory effect of SiO2 NPs in allergic airway inflammation, paving the way for new strategies in the production of nanomaterialswith lower health impact for humans.