Role of duodenal iron transporters and hepcidin in patients with alcoholic liver disease

Patients with alcoholic liver disease (ALD) often display disturbed iron indices. Hepcidin, a key regulator of iron metabolism, has been shown to be down‐regulated by alcohol in cell lines and animal models. This down‐regulation led to increased duodenal iron transport and absorption in animals. In this study, we investigated gene expression of duodenal iron transport molecules and hepcidin in three groups of patients with ALD (with anaemia, with iron overload and without iron overload) and controls. Expression of DMT1, FPN1, DCYTB, HEPH, HFE and TFR1 was measured in duodenal biopsies by using real‐time PCR and Western blot. Serum hepcidin levels were measured by using ELISA. Serum hepcidin was decreased in patients with ALD. At the mRNA level, expressions of DMT1, FPN1 and TFR1 genes were significantly increased in ALD. This pattern was even more pronounced in the subgroups of patients without iron overload and with anaemia. Protein expression of FPN1 paralleled the increase at the mRNA level in the group of patients with ALD. Serum ferritin was negatively correlated with DMT1 mRNA. The down‐regulation of hepcidin expression leading to up‐regulation of iron transporters expression in the duodenum seems to explain iron metabolism disturbances in ALD. Alcohol consumption very probably causes suppression of hepcidin expression in patients with ALD.     

New 4-deoxy-(1→3)-β-d-glucan-based oligosaccharides and their immunostimulating potential

(1→3)-β-d-Glucans are well-established natural biological immunomodulators. However, problems inherited with the natural origin of these polysaccharides bring about significant setbacks, including batch-to-batch heterogeneity and significant differences based on the source and isolation techniques. In this study, we tried to overcome these problems by preparation of a quantitatively new set of oligo-(1→3)-β-d-glucan-based synthetic immunomodulators. Some of these non-natural oligosaccharides showed biological activities, such as stimulation of phagocytosis, modulation of gene expression, and anti-cancer activity, which were superior to natural glucans.     

A molecular umbrella approach to the intracellular delivery of small interfering RNA

A series of diwalled and tetrawalled molecular umbrellas have been synthesized using cholic acid, spermidine, and lysine as starting materials. Coupling of these molecular umbrellas to an octaarginine peptide afforded agents that were capable of promoting the transport of small interfering RNA to HeLa cells, as judged by the knockdown of enhanced green fluorescent protein expression. The efficiency of this knockdown was found to increase with an increasing number of facially amphiphilic walls present, and also when a cleavable disulfide linker was replaced with a noncleavable, maleimido moiety; i.e., a group that is not susceptible to thiolate-disulfide interchange. The knockdown efficiency that was observed for one tetrawalled molecular umbrella-octaargine conjugate was comparable to that observed with a commercially available transfection agent, Lipofectamine 2000, but the conjugate showed less cytotoxicity.     

Orally administered marine (1-->3)-beta-D-glucan Phycarine stimulates both humoral and cellular immunity

(1-->3)-beta-D-Glucans represent highly conserved structural components of cell walls in yeast, fungi, or seaweed. However, it is still unknown how they mediate their effects. The aim of this study was to evaluate both intraperitoneal and oral application of seaweed-derived (1-->3)-beta-D-glucan Phycarine. Phycarine showed significant stimulation of phagocytosis by peripheral blood cells. In addition, the efficiency of chemotherapy of Lewis lung carcinoma with cyclophosphamide was potentiated by Phycarine administration. Phycarine also strongly shortened the recovery of leucopenia caused either by chemotherapy or irradiation. Besides the role in stimulation of cellular immunity, we also found a significant increase of antibody formation. Using a suckling rat model for evaluation of the absorption and tissues distribution of enterally administered (125)I-Phycarine, we found that the majority of Phycarine was detected in the stomach and duodenum 5 min after the administration. This amount sharply decreased during first 30 min. A significant amount of Phycarine entered proximal intestine in a shortly after the gavage. Its transit through proximal intestine was decreasing with time and simultaneously increasing in the ileum. Systemic blood levels were very low (less than 0.5%). Taken together, these observations suggest that Phycarine is similarly effective both after i.p. and oral application, has very strong stimulating effects on three types of experimentally induced leucopenia and stimulates both humoral and cellular branch of immune reactions. The majority of Phycarine can be detected throughout the gastrointestinal tract, supporting the feasibility of enteral administration of Phycarine in the treatment of gastrointestinal diseases.     

Modulation of cell adhesion, proliferation and differentiation on materials designed for body implants

The interaction of cells and tissues with artificial materials designed for applications in biotechnologies and in medicine is governed by the physical and chemical properties of the material surface. There is optimal cell adhesion to moderately hydrophilic and positively charged substrates, due to the adsorption of cell adhesion-mediating molecules (e.g. vitronectin, fibronectin) in an advantageous geometrical conformation, which makes specific sites on these molecules (e.g. specific amino acid sequences) accessible to cell adhesion receptors (e.g. integrins). Highly hydrophilic surfaces prevent the adsorption of proteins, or these molecules are bound very weakly. On highly hydrophobic materials, however, proteins are adsorbed in rigid and denatured forms, hampering cell adhesion. The wettability of the material surface, particularly in synthetic polymers, can be effectively regulated by physical treatments, e.g. by irradiation with ions, plasma or UV light. The irradiation-activated material surface can be functionalized by various biomolecules and nanoparticles, and this further enhances its attractiveness for cells and its effectiveness in regulating cell functions. Another important factor for cell-material interaction is surface roughness and surface topography. Nanostructured substrates (i.e. substrates with irregularities smaller than 100nm), are generally considered to be beneficial for cell adhesion and growth, while microstructured substrates behave more controversially (e.g. they can hamper cell spreading and proliferation but they enhance cell differentiation, particularly in osteogenic cells). A factor which has been relatively less investigated, but which is essential for cell-material interaction, is material deformability. Highly soft and deformable substrates cannot resist the tractional forces generated by cells during cell adhesion, and cells are not able to attach, spread and survive on such materials. Local variation in the physical and chemical properties of the material surface can be advantageously used for constructing patterned surfaces. Micropatterned surfaces enable regionally selective cell adhesion and directed growth, which can be utilized in tissue engineering, in constructing microarrays and in biosensorics. Nanopatterned surfaces are an effective tool for manipulating the type, number, spacing and distribution of ligands for cell adhesion receptors on the material surface. As a consequence, these surfaces are able to control the size, shape, distribution and maturity of focal adhesion plaques on cells, and thus cell adhesion, proliferation, differentiation and other cell functions.