Showing papers by "Annika Scheynius published in 2010"

Exosomes from human macrophages and dendritic cells contain enzymes for leukotriene biosynthesis and promote granulocyte migration

Abstract: Background Leukotrienes (LTs) are potent proinflammatory lipid mediators with key roles in the pathogenesis of asthma and inflammation. Recently, nanovesicles (exosomes), released from macrophages and dendritic cells (DCs), have become increasingly appreciated as messengers in immunity. Objective We investigated whether exosomes from human macrophages, DCs, and plasma contain enzymes for LT biosynthesis and studied potential roles for exosomes in transcellular LT metabolism and granulocyte chemotaxis. Methods The presence of LT pathway enzymes and LT biosynthesis in exosomes and cells was analyzed by Western blot, immunoelectron microscopy, and enzyme activity assays. Surface marker expression was evaluated by flow cytometry, and granulocyte migration was assessed in a multiwell chemotaxis system. Results Exosomes from macrophages and DCs contain functional enzymes for LT biosynthesis. After incubation of intact cells with the LT biosynthesis intermediate LTA 4 , LTB 4 was the major product of macrophages, whereas DCs primarily formed LTC 4 . However, in exosomes from both cell types, LTC 4 was the predominant LTA 4 metabolite. Exosomal LTC 4 formation (per milligram protein) exceeded that of cells. In macrophages and DCs, TGF-β1 upregulated LTA 4 hydrolase along with increased LTB 4 formation also in the exosomes. Moreover, TGF-β1 modified the expression of surface marker proteins on cells and exosomes and reduced the exosome yield from macrophages. On Ca 2+ -ionophore and arachidonic acid stimulation, exosomes produced chemotactic eicosanoids and induced granulocyte migration. Interestingly, active LTA 4 hydrolase and LTC 4 synthase were present also in exosomes from human plasma. Conclusion Our findings indicate that exosomes can contribute to inflammation by participation in LT biosynthesis and granulocyte recruitment.

Lifestyle and parental allergen sensitization are reflected in the intrauterine environment at gene expression level

Abstract: To cite this article: Joerink M, Oortveld MAW, Stenius F, Rindsjo E, Alm J, Scheynius A. Lifestyle and parental allergen sensitization are reflected in the intrauterine environment at gene expression level. Allergy 2010; 65: 1282–1289. Abstract Background: Environmental factors, including the intrauterine environment, can influence the risk of allergy development. In the present study, we investigated whether lifestyle and parental allergen sensitization status are reflected at gene expression level in the intrauterine environment. Methods: mRNA expression of 17 genes was determined by means of quantitative real-time PCR in term placenta of 36 families participating in the ALADDIN study (Assessment of Lifestyle and Allergic Disease During Infancy). Data were analysed using a linear regression model to estimate the influence of lifestyle and parental allergen sensitization on the relative mRNA expression levels. Immunohistochemistry on placenta biopsies was used to verify protein expression. Results: Significant differences in mRNA expression levels were detected at the foetal side of the placenta, where CD14 was expressed at higher levels in placentas from families living on a farm compared to not living on a farm, and IL-12(p40) was expressed at lower levels when the father was sensitized compared to nonsensitized. At the maternal side of the placenta, higher expression of STAT4 and lower expression of GATA3 were detected in families with sensitized compared to nonsensitized mothers, and IL-12(p40) was lower expressed when the families were living on a farm compared to not living on a farm. Immunohistochemistry performed for STAT4 and GATA3 showed that protein and mRNA levels correlated well. Conclusion: Living on a farm and parental allergen sensitization are reflected in the intrauterine environment at the gene expression level.

Malassezia Yeasts in Seborrheic and Atopic Eczemas

Abstract: Malassezia yeasts are implicated in the pathogenesis of two common diseases: seborrheic and atopic eczema. Seborrheic eczema (SE) affects areas of the body with an increased density of sebaceous glands (scalp, mid eyebrow, nasolabial folds, sternum and interscapular regions) and body folds). M. globosa and M. restricta are more commonly isolated in lesional skin, but this is also true for the isolation rate from healthy skin. In lesions of SE, a nonimmunogenic irritant reaction is recognized by immunocytochemistry. SE-specific molecular subtypes of M. globosa, M. restricta, and M. furfur have been recognized. Production of potent aryl hydrocarbon receptor ligands by Malassezia yeasts could offer new insight in the pathogenesis of SE through modulation of the immune system. The persistent and recurring nature of SE is highlighted through the existence of multiple, but not yet curative topical and systemic therapies. Atopic eczema (AE) has variable clinical presentation of skin lesions depending on the age of the patient. Three types of AE are recognized: “extrinsic,” “intrinsic,” and one-third group of patients with extrinsic or intrinsic AE showing IgE-mediated sensitization to self-antigens. Malassezia yeasts have been shown to act as allergens in AE, and thirteen allergens have been cloned, characterized, and produced as recombinant proteins from Malassezia species. Some of these recombinant allergens show a high degree of sequence identity to homologous human self antigens. The human proteins are capable of inducing positive skin prick and atopy patch tests in patients sensitized to the Malassezia proteins, indicating a role of IgE-mediated autoreactivity in the pathogenesis of AE in a subset of patients. The recombinant allergens will contribute to improve the diagnosis of sensitization to the yeast in AE patients. A correct patient stratification according to specific sensitization patterns could open novel possibilities for an immunotherapeutic treatment of a subset of AE patients in the future.