Hirohisa Takano

Recent epidemiological studies have suggested a positive link between atopy morbidity and exposure to phthalate esters, which are environmental chemicals mainly involved in house dust. Nevertheless, experimental studies applying several allergic in vivo models (in addition to epidemiological studies) are needed to prove the precise correlation between phthalates and facilitation of the allergic response/pathophysiology. Among the phthalate esters, di-(2-ethylhexyl) phthalate (DEHP) has been widely used in flexible polyvinyl chloride products, including vinyl flooring and wall covering, and has been widely suggested to have immunomodulating potential. In the present study, we examined the effects of airway exposure to DEHP on allergen (ovalbumin: OVA)-induced rhinitis in mice. The repeated administration of OVA via an intranasal route induced nasal inflammation characterized by the infiltration of granulocytes (neutrophils and eosinophils) into the nasal cavity. In this experimental setting, DEHP did not exaggerate OVA-related inflammatory pathology. However, local (nasal) IL-13 levels were significantly higher in mice treated with allergen plus DEHP than with allergen alone. Taken together, phthalate esters including DEHP have the potential to exacerbate the allergic milieu in the nasal system, as well as dermal and respiratory systems.

Nano-sized particles are diffusing in the environment with the development of nanotechnology. Polystyrene (PS) nanoparticles are modified industrial products and pharmaceutical agents, however, adverse effects of PS nanoparticles remain to be elucidated. In the present study, we investigated the effects of PS nanoparticles with different sizes on the atopic dermatitis (AD)-like skin lesions in NC/Nga mice assumed to show the skin barrier defect/dysfunction in the presence or absence of mite allergen. Male NC/Nga mice were injected intradermally with three different-sized PS nanoparticles (25, 50, or 100 nm) and/or mite allergen into their right ears. We evaluated clinical scores, ear thickening, histological findings and the local protein expression of inflammatory molecules in the ear and Ig production in serum. PS nanoparticles aggravated AD-like skin lesions related to mite allergen, which was paralleled by the local protein levels of interleukin-4, CCL2/monocyte chemotactic protein-1, CCL3/macrophage inflammatory protein-1 alpha, and CCL4/macrophage inflammatory protein-1 beta. In contrast, PS nanoparticles decreased interferon-γ expression. Furthermore, exposure to PS nanoparticles induced ear swelling and CC-chemokine expression in the absence of allergen. These effects were greater with the smaller PS nanoparticles than with the larger ones regarding overall trend. These results suggest that exposure to PS nanoparticles under skin barrier defect/dysfunction can exacerbate AD-like skin lesions related to mite allergen in a size-dependent manner. The enhancing effects may be accounted for by T helper 2-biased immune responses. Furthermore, PS nanoparticles can evoke skin inflammation via the overexpression of CC-chemokines even in the absence of allergen in atopic subjects.

Although fungi have been implicated as initiating/deteriorating factors for allergic asthma, their contributing components have not been fully elucidated. We previously isolated soluble β-glucan from Candida albicans (CSBG) (Ohno et al., 2007). In the present study, the effects of CSBG exposure on airway immunopathology in the presence or absence of other immunogenic allergen was investigated in vivo, and their cellular mechanisms were analyzed both in vivo and in vitro. In vivo, ICR mice were divided into 4 experimental groups: vehicle, CSBG (25 μg/animal), ovalbumin (OVA: 2 μg/animal), and CSBG + OVA were repeatedly administered intratracheally. The bronchoalveolar lavage cellular profile, lung histology, levels of cytokines and chemokines in the lung homogenates, the expression pattern of antigen-presenting cell (APC)-related molecules in the lung digests, and serum immunoglobulin values were studied. In vitro, the impacts of CSBG (0–12.5 μg/ml) on the phenotype and function of immune cells such as splenocytes and bone marrow-derived dendritic cells (BMDCs) were evaluated in terms of cell proliferation, the surface expression of APC-related molecules, and OVA-mediated T-cell proliferating activity. In vivo, repeated pulmonary exposure to CSBG induced neutrophilic airway inflammation in the absence of OVA, and markedly exacerbated OVA-related eosinophilic airway inflammation with mucus metaplasia in mice, which was concomitant with the amplified lung expression of Th2 cytokines and IL-17A and chemokines related to allergic response. Exposure to CSBG plus OVA increased the number of cells bearing MHC class II with or without CD80 in the lung compared to that of others. In vitro, CSBG significantly augmented splenocyte proliferation in the presence or absence of OVA. Further, CSBG increased the expression of APC-related molecules such as CD80, CD86, and DEC205 on BMDCs and amplified OVA-mediated T-cell proliferation through BMDCs. CSBG potentiates allergic airway inflammation with maladaptive Th immunity, and this potentiation was associated with the enhanced activation of APCs including DC.

The concentration of airborne particulate matters (PM) is related to daily hospital admissions for several pulmonary disorders such as bronchial asthma, acute and chronic bronchiolitis, and pneumonia. Especially, PM with a mass median aerodynamic diameter < or 2.5 μm (PM2.5) is recognized to be more closely associated with respiratory effects and subsequent mortality than that of mass median aerodynamic diameter < or 10 μm (PM10). However, there has been insufficient experimental evidence and their underlying mechanisms to support these epidemiological investigations. In this review, we introduce the adverse effects of PM, particularly, diesel exhaust particles, the main constituents of PM, on several pulmonary diseases, showing our in vivo evidence. Further, we also focus on the effects of nanoparticles, particles less than 100 nm in mass median aerodynamic diameter, on respiratory tract and disorders.

Although diesel exhaust particles (DEP) exacerbate murine allergic asthma, the mechanisms remain unclarified. This study elucidated the effects of pulmonary exposure to DEP on extrathoracic allergen-induced CD4 polarization using an ex vivo system in asthmatic mice. Mice were divided into 4 groups, and vehicle, DEP, ovalbumin (OVA), or DEP + OVA was intratracheally instilled biweekly 5 times. Twenty-four h after the last intratracheal instillation, the spleen was removed. Mononuclear cells were isolated from the spleen and stimulated in vitro with OVA; thereafter, the number of separated CD4⁺ cells was counted. The number of separated CD4⁺ cells was significantly greater in the OVA or the DEP + OVA group than in the vehicle group. Furthermore, the number was significantly greater in the DEP + OVA than in the DEP or the OVA group. Taken together, in vivo DEP exposure amplified extrathoracic CD4 polarization in asthmatic subjects.

The integration of knowledge concerning the regulation of metallothionein (MT) with research on its proposed functions is necessary to clarify how MT affects cellular processes. MT expression is induced/enhanced in various tissues by a number of physiological mediators through several response elements in the MT gene promoter. The cellular accumulation of MT depends on the availability of cellular zinc derived from the diet. MT modulates: 1) the binding and exchange/ transport of heavy metals such as zinc, cadmium, or copper under physiological conditions and cytoprotection from their toxicities, and 2) the release of gaseous mediators such as hydroxyl radicals or nitric oxide. In addition, MT reportedly affects a number of cellular processes, such as gene expression, apoptosis, proliferation, and differentiation. Given the genetic approach, the apparently healthy status of MT-deficient mice argues against an essential biological role for MT; however, the molecule may be critical in cells/tissues/organs in times of stress, since MT expression is also evoked/enhanced by various stresses. In particular, because metallothionein (MT) is induced by inflammatory stress, its roles in inflammation are implied. Also, MT expression in the lung can be enhanced by inflammatory stimuli, suggesting that its expression correlates with inflammatory lung diseases. In this paper, we review the role of MT of various inflammatory conditions in the lung.