Fabrication of porous scaffolds by three‐dimensional plotting of a pasty calcium phosphate bone cement under mild conditions

The major advantage of hydroxyapatite (HA)‐forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate‐based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three‐dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste‐like CPC (P‐CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P‐CPC showed good processability in the 3D plotting process and allowed the fabrication of stable 3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P‐CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post‐processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient‐specific requirements by simultaneous plotting of biological components. Copyright © 2012 John Wiley & Sons, Ltd.     

Seroepidemiological study in a Puumala virus outbreak area in South-East Germany

Puumala virus (PUUV) is the cause of the majority of haemorrhagic fever with renal syndrome cases in Germany. In 2004, a nephropathia epidemica outbreak was recorded in Lower Bavaria, South-East Germany. For a seroepidemiological study in this region including the resident population at four locations (n = 178) and soldiers from one location (n = 208) indirect immunoglobulin M (IgM) and immunoglobulin G (IgG) enzyme-linked immunosorbent assays (ELISAs) and immunoblot tests based on a yeast-expressed PUUV nucleocapsid protein were established. The validation using human serum panels originating from Germany revealed a diagnostic sensitivity and specificity of 98/100% for the IgM ELISA, 99/99% for the IgG ELISA, 99/100% for the IgM immunoblot test and 100/96% for the IgG immunoblot test. Using the novel IgG assays as well as a commercial IgG ELISA and an immunofluorescence assay for the resident population an average prevalence of 6.7% (12 of 178) with a range of 0% (0 of 21) to 11.9% (7 of 59) was observed. Positive serological results were equally distributed between males and females with an average age of 63 for males and 52 for females. The seroprevalence in the soldier group was found to be about 1% with one positive male of 203 (age 46 years) and one positive female of five (age 47 years). In conclusion, the PUUV seroprevalence in the residents of the outbreak region in Lower Bavaria was found to be up to fivefold higher than the average hantavirus seroprevalence of the German population.     

IL-22 and IL-20 are key mediators of the epidermal alterations in psoriasis while IL-17 and IFN-γ are not

Psoriasis is a common chronic skin disease with a largely unknown pathogenesis. We demonstrate here that transgenic over-expression of interleukin (IL)-22 in mice resulted in neonatal mortality and psoriasis-like skin alterations including acanthosis and hypogranularity. This cutaneous phenotype may be caused by the direct influence of IL-22 on keratinocytes, since this cytokine did not affect skin fibroblasts, endothelial cells, melanocytes, or adipocytes. The comparison of cytokines with hypothesized roles in psoriasis pathogenesis determined that neither interferon (IFN)-γ nor IL-17, but only IL-22 and, with lower potency, IL-20 caused psoriasis-like morphological changes in a three-dimensional human epidermis model. These changes were associated with inhibited keratinocyte terminal differentiation and with STAT3 upregulation. The IL-22 effect on differentiation-regulating genes was STAT3-dependent. In contrast to IL-22 and IL-20, IFN-γ and IL-17 strongly induced T-cell and neutrophilic granulocyte-attracting chemokines, respectively. Tumor necrosis factor-α potently induced diverse chemokines and additionally enhanced the expression of IL-22 receptor pathway elements and amplified some IL-22 effects. This study suggests that different cytokines are players in the psoriasis pathogenesis although only the IL-10 family members IL-22 and IL-20 directly cause the characteristic epidermal alterations. Kerstin Wolk and Harald S. Haugen equally contributed to this work.     

Acute and long-term humoral immunity following active immunization of rabbits with inacctivated spores of various Encephalitozoon species

Microsporidia of the genus Encephalitozoon are increasingly being reported as a cause of severe, often disseminated infections, mainly in patients with acquired immunodeficiency syndrome (AIDS). Immunological identification of each of the three recognized species (E. cuniculi, E. hellem, and E. intestinalis) requires the availability of specific immune sera. All sera available thus far have been generated by direct inoculation of rabbits with virulent microsporidian spores. This study demonstrates for the first time that subcutaneous immunization with inactivated spores of E. cuniculi, E. hellem, or E. intestinalis is capable of generating highly active rabbit hyperimmune sera to the homologous antigens, with maximal titers being 1:5,120, 1:1,280, and 1:2,560, respectively, as determined by the indirect immunofluorescence technique (IIF). Broad cross-reactivity of the rabbit antisera with all heterologous Encephalitozoon antigens was determined by IIF and immunogold electron microscopy; however, only the E. hellem immune serum strongly cross-reacted with spores of Enterocytozoon bieneusi. During the 35-month follow-up period the antibody titers to the homologous antigens declined to 1:640, 1:160, and 1:320, respectively. The observed decay curves for antibody titers against E. cuniculi, E. hellem, and E. intestinalis were fitted using mathematical modeling, resulting in a predicted duration for specific immune responses of about 7 years on average. Knowledge of the magnitude and duration of specific immune responses is a prerequisite for further evaluation of the concept of using inactivated microsporidian spores in the quest for vaccines against microsporidian infections. Received: 10 April 2000 / Accepted: 18 July 2000     

Autotrophy as a predominant mode of carbon fixation in anaerobic methane-oxidizing microbial communities

The methane-rich, hydrothermally heated sediments of the Guaymas Basin are inhabited by thermophilic microorganisms, including anaerobic methane-oxidizing archaea (mainly ANME-1) and sulfate-reducing bacteria (e.g., HotSeep-1 cluster). We studied the microbial carbon flow in ANME-1/ HotSeep-1 enrichments in stable-isotope–probing experiments with and without methane. The relative incorporation of ¹³C from either dissolved inorganic carbon or methane into lipids revealed that methane-oxidizing archaea assimilated primarily inorganic carbon. This assimilation is strongly accelerated in the presence of methane. Experiments with simultaneous amendments of both ¹³C-labeled dissolved inorganic carbon and deuterated water provided further insights into production rates of individual lipids derived from members of the methane-oxidizing community as well as their carbon sources used for lipid biosynthesis. In the presence of methane, all prominent lipids carried a dual isotopic signal indicative of their origin from primarily autotrophic microbes. In the absence of methane, archaeal lipid production ceased and bacterial lipid production dropped by 90%; the lipids produced by the residual fraction of the metabolically active bacterial community predominantly carried a heterotrophic signal. Collectively our results strongly suggest that the studied ANME-1 archaea oxidize methane but assimilate inorganic carbon and should thus be classified as methane-oxidizing chemoorganoautotrophs.     

Long-lived plasma cells in immunity and immunopathology

Following tetanus vaccination, a wave of antibody-secreting cells appear in the peripheral blood composed of vaccine-specific, migratory plasmablasts and plasma cells secreting antibodies specific for other antigens. The latter probably were tissue resident plasma cells formed in earlier immune responses that are mobilized due to competition with the newly formed tetanus-specific plasmablasts. Newly formed plasma cells secreting antibodies specific for a particular antigen/vaccine are accommodated in the bone marrow likely at the global expense of the pre-existing long-lived plasma cell population providing humoral memory for other antigens. Plasmablasts but not mature plasma cells are attracted by the ligands for the chemokine receptors CXCR4 and CXCR3. While CXCR4 and its cognate ligand is important for plasma cell homing to the bone marrow, CXCR3 and its ligand IP10 are likely to be involved in attracting them to inflamed tissue. In NZB/W mice, a model for systemic lupus, long-lived autoreactive plasma cells are present not only in bone marrow, but also in inflamed tissues and spleen. Autoreactive plasma cells in the spleen are present long before the onset of the disease, suggesting that these cells contribute to induction of immunopathology.