T-cell activation and bacterial infection in skin wounds of recessive dystrophic epidermolysis bullosa patients.

Recessive dystrophic epidermolysis bullosa (RDEB) patients develop poorly healing skin wounds that are frequently colonized with microbiota. Because T cells play an important role in clearing such pathogens, we aimed to define the status of adaptive T cell-mediated immunity in RDEB wounds. Using a non-invasive approach for sampling of wound-associated constituents, we evaluated microbial contaminants in cellular fraction and exudates obtained from RDED wounds.

Intracellular escape strategies of Staphylococcus aureus in persistent cutaneous infections.

Pathogenic invasion of Staphylococcus aureus is a major concern in patients with chronic skin diseases like atopic dermatitis (AD), epidermolysis bullosa (EB), or chronic diabetic foot and venous leg ulcers, and can result in persistent and life-threatening chronic non-healing wounds. Staphylococcus aureus is generally recognized as extracellular pathogens. However, S.

Aberrant recruitment of leukocytes defines poor wound healing in patients with recessive dystrophic epidermolysis bullosa.

Background: Poorly healing wounds are one of the major complications in patients suffering from recessive dystrophic epidermolysis bullosa (RDEB). At present, there are no effective means to analyze changes in cellular and molecular networks occurring during RDEB wound progression to predict wound outcome and design betted wound management approaches.

Objectives: To better define mechanisms influencing RDEB wound progression by evaluating changes in molecular and cellular networks.

Spine Patterning Is Guided by Segmentation of the Notochord Sheath.

The spine is a segmented axial structure made of alternating vertebral bodies (centra) and intervertebral discs (IVDs) assembled around the notochord. Here, we show that, prior to centra formation, the outer epithelial cell layer of the zebrafish notochord, the sheath, segments into alternating domains corresponding to the prospective centra and IVD areas. This process occurs sequentially in an anteroposterior direction via the activation of Notch signaling in alternating segments of the sheath, which transition from cartilaginous to mineralizing domains.

defines a wound-specific sheath cell subpopulation associated with notochord repair.

Regenerative therapy for degenerative spine disorders requires the identification of cells that can slow down and possibly reverse degenerative processes. Here, we identify an unanticipated wound-specific notochord sheath cell subpopulation that expresses Wilms Tumor (WT) 1b following injury in zebrafish. We show that localized damage leads to Wt1b expression in sheath cells, and that cells migrate into the wound to form a stopper-like structure, likely to maintain structural integrity.

High-Density Lipoproteins Exert Pro-inflammatory Effects on Macrophages via Passive Cholesterol Depletion and PKC-NF-κB/STAT1-IRF1 Signaling.

Membrane cholesterol modulates a variety of cell signaling pathways and functions. While cholesterol depletion by high-density lipoproteins (HDLs) has potent anti-inflammatory effects in various cell types, its effects on inflammatory responses in macrophages remain elusive. Here we show overt pro-inflammatory effects of HDL-mediated passive cholesterol depletion and lipid raft disruption in murine and human primary macrophages in vitro.

The contribution of NF-κB signalling to immune regulation and tolerance.

Background: Immune regulation is necessary to control inflammatory responses and to prevent autoimmune diseases. Therefore, mechanisms of central and peripheral tolerance have evolved to ensure that T cells recognize antigens as self- or non-self-antigens. The thymus is crucially important for central tolerance induction to self-antigens via negative selection of T cells.

Deficiency in macrophage-stimulating protein results in spontaneous intestinal inflammation and increased susceptibility toward epithelial damage in zebrafish.

Several genome-wide association studies have identified the genes encoding for macrophage-stimulating protein (MSP) and its receptor RON (Recepteur d'Origine Nantais) as possible susceptibility factors in inflammatory bowel disease. While it has been shown that the MSP-RON signaling pathway is involved in tissue injury responses, current mouse models for MSP and RON deficiency have not clearly demonstrated a role of MSP-RON signaling in the context of intestinal inflammation. In this study, we report that the recently identified zebrafish Msp mutant (msp(t34230)) develops spontaneous intestinal inflammation over time.

Zebrafish enpp1 mutants exhibit pathological mineralization, mimicking features of generalized arterial calcification of infancy (GACI) and pseudoxanthoma elasticum (PXE).

In recent years it has become clear that, mechanistically, biomineralization is a process that has to be actively inhibited as a default state. This inhibition must be released in a rigidly controlled manner in order for mineralization to occur in skeletal elements and teeth. A central aspect of this concept is the tightly controlled balance between phosphate, a constituent of the biomineral hydroxyapatite, and pyrophosphate, a physiochemical inhibitor of mineralization.

Mature osteoblasts dedifferentiate in response to traumatic bone injury in the zebrafish fin and skull.

Zebrafish have an unlimited capacity to regenerate bone after fin amputation. In this process, mature osteoblasts dedifferentiate to osteogenic precursor cells and thus represent an important source of newly forming bone. By contrast, differentiated osteoblasts do not appear to contribute to repair of bone injuries in mammals; rather, osteoblasts form anew from mesenchymal stem cells.

Proteomics analysis of the zebrafish skeletal extracellular matrix.

The extracellular matrix of the immature and mature skeleton is key to the development and function of the skeletal system. Notwithstanding its importance, it has been technically challenging to obtain a comprehensive picture of the changes in skeletal composition throughout the development of bone and cartilage. In this study, we analyzed the extracellular protein composition of the zebrafish skeleton using a mass spectrometry-based approach, resulting in the identification of 262 extracellular proteins, including most of the bone and cartilage specific proteins previously reported in mammalian species.

Entpd5 is essential for skeletal mineralization and regulates phosphate homeostasis in zebrafish.

Bone mineralization is an essential step during the embryonic development of vertebrates, and bone serves vital functions in human physiology. To systematically identify unique gene functions essential for osteogenesis, we performed a forward genetic screen in zebrafish and isolated a mutant, no bone (nob), that does not form any mineralized bone. Positional cloning of nob identified the causative gene to encode ectonucleoside triphosphate/diphosphohydrolase 5 (entpd5); analysis of its expression pattern demonstrates that entpd5 is specifically expressed in osteoblasts.

Macrophage-stimulating protein and calcium homeostasis in zebrafish.

To systematically identify novel gene functions essential for osteogenesis and skeletal mineralization, we performed a forward genetic mutagenesis screen in zebrafish and isolated a mutant that showed delayed skeletal mineralization. Analysis of the mutant phenotype in an osterix:nuclear-GFP transgenic background demonstrated that mutants contain osterix-expressing osteoblasts comparable to wild-type embryos. Positional cloning revealed a premature stop mutation in the macrophage-stimulating protein (msp) gene, predicted to result in a biologically inactive protein.

Trpv5/6 is vital for epithelial calcium uptake and bone formation.

Calcium is an essential ion serving a multitude of physiological roles. Aside from its role as a second messenger, it is an essential component of the vertebrate bone matrix. Efficient uptake and storage of calcium are therefore indispensable for all vertebrates.

Soluble factors released by ATDC5 cells affect the formation of calcium phosphate crystals.

During biomineralization the organism controls the nature, orientation, size and shape of the mineral phase. The aim of this study was to investigate whether proteins or vesicles that are constitutively released by growing ATDC5 cells have the ability to affect the formation of the calcium phosphate crystal. Therefore, subconfluent cultured ATDC5 cells were incubated for 1 h in medium without serum.

What triggers cell-mediated mineralization?

Mineralization is an essential requirement for normal skeletal development, but under certain pathological conditions organs like articular cartilage and cardiovascular tissue are prone to unwanted mineralization. Recent findings suggest that the mechanisms regulating skeletal mineralization may be similar to those regulating pathological mineralization. In general, three forms of cell-mediated mineralization are recognized in an organism: intramembranous ossification, endochondral ossification and pathological mineralization.

Iron ions derived from the nitric oxide donor sodium nitroprusside inhibit mineralization.

Sodium nitroprusside (SNP) is a nitric oxide (NO) donor drug, which is therapeutically used as a vasodilating drug in heart transplantations. In our previous study it was found that SNP at a concentration of 100 microM inhibited mineralization in a cell culture system, indicating that the beneficial effects of this drug may also include inhibition of vascular calcification. The aim of this study was to investigate which bioactive compounds generated from SNP inhibit mineralization.