Über das Restitutionsvermögen der Blätter von Bryophyllum calycinum Salisb

Ohne ZusammenfassungMit 2 Textabbildungen.     

The Neck Region of the C-type Lectin DC-SIGN Regulates Its Surface Spatiotemporal Organization and Virus-binding Capacity on Antigen-presenting Cells

The C-type lectin DC-SIGN expressed on dendritic cells (DCs) facilitates capture and internalization of a plethora of different pathogens. Although it is known that DC-SIGN organizes in nanoclusters at the surface of DCs, the molecular mechanisms responsible for this well defined nanopatterning and role in viral binding remain enigmatic. By combining biochemical and advanced biophysical techniques, including optical superresolution and single particle tracking, we demonstrate that DC-SIGN intrinsic nanoclustering strictly depends on its molecular structure. DC-SIGN nanoclusters exhibited free, Brownian diffusion on the cell membrane. Truncation of the extracellular neck region, known to abrogate tetramerization, significantly reduced nanoclustering and concomitantly increased lateral diffusion. Importantly, DC-SIGN nanocluster dissolution exclusively compromised binding to nanoscale size pathogens. Monte Carlo simulations revealed that heterogeneity on nanocluster density and spatial distribution confers broader binding capabilities to DC-SIGN. As such, our results underscore a direct relationship between spatial nanopatterning, driven by intermolecular interactions between the neck regions, and receptor diffusion to provide DC-SIGN with the exquisite ability to dock pathogens at the virus length scale. Insight into how virus receptors are organized prior to virus binding and how they assemble into functional platforms for virus docking is helpful to develop novel strategies to prevent virus entry and infection.     

The role of tetraspanins in the pathogenesis of infectious diseases

Tetraspanin proteins on host cells are involved in the pathogenesis of infectious diseases at different stages. In this review, we will focus on tetraspanins expressed in the immune system and the role they play in the defense to viral, bacterial, parasitic and fungal infections.     

Transarterial chemoembolisation (TACE) using irinotecan-loaded beads for the treatment of unresectable metastases to the liver in patients with colorectal cancer: an interim report

Background

Following failure of standard systemic chemotherapy, the role of hepatic transarterial therapy for colorectal hepatic metastasis continues to evolve as the experience with this technique matures. The aim of this study to gain a better understanding of the value of drug eluting bead therapy when administered to patients with unresectable colorectal hepatic metastasis.

Methods

This was an open-label, multi-center, single arm study, of unresectable colorectal hepatic metastasis patients who had failed standard therapy from 10/2006-10/2008. Patients received repeat embolizations with Irinotecan loaded beads(max 100 mg per embolization) per treating physician's discretion.

Results

Fifty-five patients underwent 99 treatments using Irinotecan drug eluting beads. The median number of total treatments per patient was 2(range of 1-5). Median length of hospital stay was 23 hours(range 23 hours - 10 days). There were 30(30%) sessions associated with adverse reactions during or after the treatment. The median disease free and overall survival from the time of first treatment was 247 days and 343 days. Six patients(10%) were downstaged from their original disease status. Of these, four were treated with surgery and two with RFA. Neither number of liver lesions, size of liver lesions or extent of liver replacement(<= 25% vs >25%) were predictors of overall survival. Only the presence of extrahepatic disease(p = 0,001), extent of prior chemotherapy (failed 1^st and 2^nd line vs > 2 line failure)(p = 0,007) were predictors of overall survival in multivariate analysis.

Conclusion

Chemoembolization using Irinotecan loaded beads was safe and effective in the treatment of patients as demonstrated by a minimal complication rate and acceptable tumor response.     

A critical role for prostaglandin E2 in podosome dissolution and induction of high-speed migration during dendritic cell maturation

Dendritic cells (DCs) are professional APCs of the immune system that play a key role in regulating T cell-based immunity. The capacity of DCs to activate T cells depends on their maturation state as well as their ability to migrate to the T cell areas of draining lymph nodes. In this study, we investigated the effects of DC maturation stimuli on the actin cytoskeleton and beta(1) integrin-dependent adhesion and migration. Podosomes, specialized adhesion structures found in immature monocyte-derived DCs as well as myeloid DCs, rapidly dissolve in response to maturation stimuli such as TNF-alpha and PGE(2), whereas the TLR agonist LPS induces podosome dissolution only after a long lag time. We demonstrate that LPS-mediated podosome disassembly as well as the onset of high-speed DC migration are dependent on the production of PGs by the DCs. Moreover, both of these processes are inhibited by Ab-induced activation of beta(1) integrins. Together, these results show that maturation-induced podosome dissolution and loss of alpha(5)beta(1) integrin activity allow human DCs to undergo the transition from an adhesive to a highly migratory phenotype.     

KIM127, an Antibody that Promotes Adhesion, Maps to a Region of CD18 that Includes Cysteine-Rich Repeats

A series of fusion proteins have been generated between human and mouse CD18. These proteins have been used to carry out preliminary mapping studies on a number of anti-CD18 antibodies including KIM127 an antibody that promotes CD18-dependent adhesion. This antibody maps to a region of the CD18 molecule between amino acids 406 and 570 in a region containing cysteine-rich repeats.     

Amplified centrosomes may underlie aggressive disease course in pancreatic ductal adenocarcinoma

Centrosome amplification (CA), the presence of centrosomes that are abnormally numerous or enlarged, is a well-established driver of tumor initiation and progression associated with poor prognosis across a diversity of malignancies. Pancreatic ductal adenocarcinoma (PDAC) carries one of the most dismal prognoses of all cancer types. A majority of these tumors are characterized by numerical and structural centrosomal aberrations, but it is unknown how CA contributes to the disease and patient outcomes. In this study, we sought to determine whether CA was associated with worse clinical outcomes, poor prognostic indicators, markers of epithelial-mesenchymal transition (EMT), and ethnicity in PDAC. We also evaluated whether CA could precipitate more aggressive phenotypes in a panel of cultured PDAC cell lines. Using publicly available microarray data, we found that increased expression of genes whose dysregulation promotes CA was associated with worse overall survival and increased EMT marker expression in PDAC. Quantitative analysis of centrosomal profiles in PDAC cell lines and tissue sections uncovered varying levels of CA, and the expression of CA markers was associated with the expression of EMT markers. We induced CA in PDAC cells and found that CA empowered them with enhanced invasive and migratory capabilities. In addition, we discovered that PDACs from African American (AA) patients exhibited a greater extent of both numerical and structural CA than PDACs from European American (EA) patients. Taken together, these findings suggest that CA may fuel a more aggressive disease course in PDAC patients.     

Wild-type and modified gp100 peptide-pulsed dendritic cell vaccination of advanced melanoma patients can lead to long-term clinical responses independent of the peptide used

Dendritic cell (DC)-based immunotherapy is explored worldwide in cancer patients. Several strategies have been employed to load DC with antigen, including peptide loading. To increase immunogenicity of peptides, major histocompatibility complex (MHC) class I binding affinity and stability of peptide-MHC complexes at the cell surface may be improved by modification of the amino acid sequence. In this study, we compared the capacity of DC loaded with wild-type versus modified gp100 peptides with higher binding affinities to induce an immune and clinical response in advanced melanoma patients. Metastatic HLA-A2.1(+) melanoma patients were vaccinated intravenously (on average 25?×?10(6) DC) and intradermally (on average 11?×?10(6) DC) with mature DC loaded with keyhole limpet hemocyanin (KLH) together with tyrosinase peptide and either wild-type (15 patients) or modified (12 patients) gp100 peptides. All vaccinated patients showed a pronounced proliferative T cell or humoral response against KLH. Gp100-specific T cell responses were monitored in post-treatment delayed type hypersensitivity (DTH) skin biopsies by tetramer and functional analysis. Antigen-specific T cells were found in 2 of 15 patients vaccinated with wild-type gp100-loaded DC, versus 1 of 12 patients vaccinated with modified peptide-loaded DC. These three patients also had the best clinical response, with long-term (>8?years) complete responses in two patients, one in each group. We conclude that vaccination with peptide-loaded DC can result in long-term clinical responses in a minority of metastatic melanoma patients, and that the use of modified as compared to wild-type gp100 peptides for DC loading does not result in a relevant enhanced immune responses.     

Myosin II and mechanotransduction: a balancing act

Adherent cells respond to mechanical properties of the surrounding extracellular matrix. Mechanical forces, sensed at specialized cell-matrix adhesion sites, promote actomyosin-based contraction within the cell. By manipulating matrix rigidity and adhesion strength, new roles for actomyosin contractility in the regulation of basic cellular functions, including cell proliferation, migration and stem cell differentiation, have recently been discovered. These investigations demonstrate that a balance of forces between cell adhesion on the outside and myosin II-based contractility on the inside of the cell controls many aspects of cell behavior. Disturbing this balance contributes to the pathogenesis of various human diseases. Therefore, elaborate signaling networks have evolved that modulate myosin II activity to maintain tensional homeostasis. These include signaling pathways that regulate myosin light chain phosphorylation as well as myosin II heavy chain interactions.     

Bacteria–bacteria interactions within the microbiota of the ancestral metazoan Hydra contribute to fungal resistance

Epithelial surfaces of most animals are colonized by diverse microbial communities. Although it is generally agreed that commensal bacteria can serve beneficial functions, the processes involved are poorly understood. Here we report that in the basal metazoan Hydra, ectodermal epithelial cells are covered with a multilayered glycocalyx that provides a habitat for a distinctive microbial community. Removing this epithelial microbiota results in lethal infection by the filamentous fungus Fusarium sp. Restoring the complex microbiota in gnotobiotic polyps prevents pathogen infection. Although mono-associations with distinct members of the microbiota fail to provide full protection, additive and synergistic interactions of commensal bacteria are contributing to full fungal resistance. Our results highlight the importance of resident microbiota diversity as a protective factor against pathogen infections. Besides revealing insights into the in vivo function of commensal microbes in Hydra, our findings indicate that interactions among commensal bacteria are essential to inhibit pathogen infection.