Mast Cell-Specific Expression of Human Siglec-8 in Conditional Knock-in Mice.

Sialic acid-binding Ig-like lectin 8 (Siglec-8) is expressed on the surface of human eosinophils, mast cells, and basophils-cells that participate in allergic and other diseases. Ligation of Siglec-8 by specific glycan ligands or antibodies triggers eosinophil death and inhibits mast cell degranulation; consequences that could be leveraged as treatment. However, Siglec-8 is not expressed in murine and most other species, thus limiting preclinical studies in vivo.

CD8 T cells in innate immune responses: using STAT4-dependent but antigen-independent pathways to gamma interferon during viral infection.

The cytokine gamma interferon (IFN-γ), with antimicrobial and immunoregulatory functions, can be produced by T cells following stimulation through their T cell receptors (TCRs) for antigen. The innate cytokines type 1 IFNs and interleukin-12 (IL-12) can also stimulate IFN-γ production by natural killer (NK) but not naive T cells. High basal expression of signal transducer and activator of transcription 4 (STAT4), used by type 1 IFN and IL-12 to induce IFN-γ as well as CD25, contributes to the NK cell responses.

Acidic mammalian chitinase is not a critical target for allergic airway disease.

The expression of acidic mammalian chitinase (AMCase) is associated with Th2-driven respiratory disorders. To investigate the potentially pathological role of AMCase in allergic airway disease (AAD), we sensitized and challenged mice with ovalbumin or a combination of house dust mite (HDM) plus cockroach allergen. These mice were treated or not treated with small molecule inhibitors of AMCase, which significantly reduced allergen-induced chitinolytic activity in the airways, but exerted no apparent effect on pulmonary inflammation per se.

Type 1 interferon induction of natural killer cell gamma interferon production for defense during lymphocytic choriomeningitis virus infection.

Unlabelled: Natural killer (NK) cells are equipped to innately produce the cytokine gamma interferon (IFN-γ) in part because they basally express high levels of the signal transducer and activator of transcription 4 (STAT4). Type 1 interferons (IFNs) have the potential to activate STAT4 and promote IFN-γ expression, but concurrent induction of elevated STAT1 negatively regulates access to the pathway. As a consequence, it has been difficult to detect type 1 IFN stimulation of NK cell IFN-γ during viral infections in the presence of STAT1 and to understand the evolutionary advantage for maintaining the pathway.

Stem cell continuum: directed differentiation hotspots.

Objective: The purpose of this study was to evaluate the technique of stem cell-directed differentiation in the context of cell-cycle position. The hypothesis was that stem cells would have different sensitivities to an identical inductive signal through cell-cycle transit and that this would affect the outcome of its progeny.

Materials And Methods: Differentiation of murine marrow lineage(negative)rhodamine-123(low-)Hoechst-33342(low) (LRH) stem cells was determined at different points in cell cycle under stimulation by thrombopoietin, flt3 ligand, and steel factor.

Bone marrow production of lung cells: the impact of G-CSF, cardiotoxin, graded doses of irradiation, and subpopulation phenotype.

Objective: Previous studies have demonstrated the production of various types of lung cells from marrow cells under diverse experimental conditions. Our aim was to identify some of the variables that influence conversion in the lung.

Methods: In separate experiments, mice received various doses of total-body irradiation followed by transplantation with whole bone marrow or various subpopulations of marrow cells (Lin(-/+), c-kit(-/+), Sca-1(-/+)) from GFP(+) (C57BL/6-TgN[ACTbEGFP]1Osb) mice.

The stem cell continuum.

Hematopoietic stem cells have been felt to exist in a hierarchical structure with a relatively fixed phenotype at each stage of differentiation. Recent studies on the phenotype of the marrow hematopoietic stem cell indicate that it is not a fixed entity, but rather that it fluctuates and shows marked heterogeneity. Past studies have shown that stem cell engraftment characteristics, adhesion protein, and gene expression varies with the phase of the cell cycle.

Critical variables in the conversion of marrow cells to skeletal muscle.

We have studied conversion of marrow cells to skeletal muscle in cardiotoxin-injured anterior tibialis muscle in a green fluorescent protein (GFP) to C57BL/6 transplantation model and ascertained that total body irradiation (TBI) with establishment of chimerism is a critical factor. Local irradiation has little effect in lower doses and was detrimental at higher doses. Whole body (1000 cGy) with shielding of the leg or a combination of 500 cGy TBI and 500 cGy local radiations was found to give the best results.

Robust conversion of marrow cells to skeletal muscle with formation of marrow-derived muscle cell colonies: a multifactorial process.

Objective: Murine marrow cells are capable of repopulating skeletal muscle fibers. A point of concern has been the "robustness" of such conversions. We have investigated the impact of type of cell delivery, muscle injury, nature of delivered cell, and stem cell mobilizations on marrow-to-muscle conversion.

Homing and conversion of murine hematopoietic stem cells to lung.

The hematopoietic stem cell population, lineage negative-Sca positive (HSC), displays a homing defect into bone marrow (BM) after 48-h exposure to interleukin (IL)-3, IL-6, IL-11, and steel factor [J. Hematother. Stem Cell Res.

Differentiation hotspots: the deterioration of hierarchy and stochasm.

The conception of the present-day model of hematopoiesis was begun by the work of Professor Ernst Neumann in the 19th century when he established that immature blood cells in the bone marrow migrate out into the blood vessels. Here was the birth of the hierarchical model of hematopoiesis. Jumping 135 years into the present day, recent data suggests that the stem cell regulation is not based on the classic hierarchical model, but instead more on a functional continuum.

Stem cell plasticity: an overview.

The capacity of adult bone marrow cells to convert to cells of other tissues, referred to by many as stem cell plasticity, was the focus of the meeting in Providence entitled "Challenges in the Era of Stem Cell Plasticity". The meeting provided a showcase for the many impressive positive results on tissue restoration including the capacity of purified marrow stem cells to restore heart, skin, and liver function in impaired mice or humans. This area of research has become a center of controversy, although it is not clear why.

A method for clonal analysis of epidermal growth factor-responsive neural progenitors.

Epidermal growth factor (EGF) responsive neural progenitors are defined by clonal growth from single cells. In previous studies we were unable to obtain clones at single cell densities using trypsinized cells and trituration alone always gave cellular aggregates. Here we report on single cell derived clones using a technique involving trituration of EGF responsive neurospheres, cell filtration, and single cell sorting using a MoFlo high speed fluorescence activated cell sorter.