Neutrophil Activities in Human Ocular Toxoplasmosis: An In Vitro Study With Human Cells.

Purpose: Retinal damage in ocular toxoplasmosis reflects Toxoplasma gondii-induced cell lysis and reactive inflammation. Human retinal histopathology demonstrates the presence of neutrophils, but activities of this leukocyte subset are unstudied. We conducted in vitro experiments to evaluate roles for neutrophils as retinal taxis for T. gondii and as contributors to the inflammation. Methods: Human neutrophils were isolated from peripheral blood. Migration to disease-relevant chemokines was evaluated in transwells, seeded with human retinal endothelial cells for some assays, using neutrophils infected with GT-1 strain T. gondii tachyzoites. Neutrophils were cocultured with T. gondii-infected ARPE-19 and primary human retinal pigment epithelial cells, and production of reactive oxygen species (ROS) was estimated by dihydroethidium reaction. Proteins produced by T. gondii-infected ARPE-19 cells were profiled by immunoarray, and candidate neutrophil-activating proteins were targeted with specific blocking antibody in coculture assays. Results: Infection with T. gondii arrested neutrophil migration across retinal endothelium regardless of the presence of CXCL8. Migration to CXCL1, CXCL2, and CXCL8 also was significantly inhibited in infected neutrophils. Neutrophils generated more ROS when cocultured with infected versus uninfected ARPE-19 cells and three of four primary retinal pigment epithelial cell isolates. Infected ARPE-19 cells augmented the synthesis of 12 neutrophil-activating proteins also expressed by primary retinal pigment epithelial cells. Antibody blockade of granulocyte-macrophage colony-stimulating factor, interleukin-6 (IL-6) and IL-18 significantly reduced ROS production by neutrophils cocultured with T. gondii-infected ARPE-19 cells. Conclusions: Our findings support involvement of neutrophils in retinal inflammation, but not parasite transport, in the setting of ocular toxoplasmosis.

A genome wide association scan for (1,3;1,4)-ß-glucan content in the grain of contemporary 2-row Spring and Winter barleys.

BACKGROUND: (1,3;1,4)-ß-Glucan is an important component of the cell walls of barley grain as it affects processability during the production of alcoholic beverages and has significant human health benefits when consumed above recommended threshold levels. This leads to diametrically opposed quality requirements for different applications as low levels of (1,3;1,4)-ß-glucan are required for brewing and distilling and high levels for positive impacts on human health. RESULTS: We quantified grain (1,3;1,4)-ß-glucan content in a collection of 399 2-row Spring-type, and 204 2-row Winter-type elite barley cultivars originating mainly from north western Europe. We combined these data with genotypic information derived using a 9 K Illumina iSelect SNP platform and subsequently carried out a Genome Wide Association Scan (GWAS). Statistical analysis accounting for residual genetic structure within the germplasm collection allowed us to identify significant associations between molecular markers and the phenotypic data. By anchoring the regions that contain these associations to the barley genome assembly we catalogued genes underlying the associations. Based on gene annotations and transcript abundance data we identified candidate genes. CONCLUSIONS: We show that a region of the genome on chromosome 2 containing a cluster of CELLULOSE SYNTHASE-LIKE (Csl) genes, including CslF3, CslF4, CslF8, CslF10, CslF12 and CslH, as well as a region on chromosome 1H containing CslF9, are associated with the phenotype in this germplasm. We also observed that several regions identified by GWAS contain glycoside hydrolases that are possibly involved in (1,3;1,4)-ß-glucan breakdown, together with other genes that might participate in (1,3;1,4)-ß-glucan synthesis, re-modelling or regulation. This analysis provides new opportunities for understanding the genes related to the regulation of (1,3;1,4)-ß-glucan content in cereal grains.

L-Proline induces differentiation of ES cells: a novel role for an amino acid in the regulation of pluripotent cells in culture.

The development of cell therapeutics from embryonic stem (ES) cells will require technologies that direct cell differentiation to specific somatic cell lineages in response to defined factors. The initial step in formation of the somatic lineages from ES cells, differentiation to an intermediate, pluripotent primitive ectoderm-like cell, can be achieved in vitro by formation of early primitive ectoderm-like (EPL) cells in response to a biological activity contained within the conditioned medium MEDII. Fractionation of MEDII has identified two activities required for EPL cell formation, an activity with a molecular mass of <3 kDa and a second, much larger species. Here, we have identified the low-molecular-weight activity as l-proline. An inhibitor of l-proline uptake, glycine, prevented the differentiation of ES cells in response to MEDII. Supplementation of the culture medium of ES cells with >100 M l-proline and some l-proline-containing peptides resulted in changes in colony morphology, cell proliferation, gene expression, and differentiation kinetics consistent with differentiation toward a primitive ectoderm-like cell. This activity appeared to be associated with l-proline since other amino acids and analogs of proline did not exhibit an equivalent activity. Activation of the mammalian target of rapamycin (mTOR) signaling pathway was found to be necessary but not sufficient for l-proline activity; addition of other activators of the mTOR signaling pathway failed to alter the ES cell phenotype. This is the first report describing a role for amino acids in the regulation of pluripotency and cell differentiation and identifies a novel role for the imino acid l-proline.

Manipulation of cell:cell contacts and mesoderm suppressing activity direct lineage choice from pluripotent primitive ectoderm-like cells in culture.

In the mammal, the pluripotent cells of embryo differentiate and commit to either the mesoderm/endoderm lineages or the ectoderm lineage during gastrulation. In culture, the ability to direct lineage choice from pluripotent cells into the mesoderm/endoderm or ectoderm lineages will enable the development of technologies for the formation of highly enriched or homogenous populations of cells. Here we show that manipulation of cell:cell contact and a mesoderm suppressing activity in culture affects the outcome of pluripotent cell differentiation and when both variables are manipulated appropriately they can direct differentiation to either the mesoderm or ectoderm lineage. The disruption of cell:cell contacts and removal of a mesoderm suppressor activity results in the differentiation of pluripotent, primitive ectoderm-like cells to the mesoderm lineage, while maintenance of cell:cell contacts and inclusion, within the culture medium, of a mesoderm suppressing activity results in the formation of near homogenous populations of ectoderm. Understanding the contribution of these variables in lineage choice provides a framework for the development of directed differentiation protocols that result in the formation of specific cell populations from pluripotent cells in culture.

Identification of a biological activity that supports maintenance and proliferation of pluripotent cells from the primitive ectoderm of the mouse.

Pluripotent cell development in the mammalian embryo results in the sequential formation of several developmentally distinct populations, inner cell mass, primitive ectoderm, and the primordial germ lineage. Factors within medium conditioned by HepG2 cells (MEDII) have been implicated in the formation and maintenance of primitive ectoderm from inner cell mass cells both in vitro and in vivo. Here we demonstrate that MEDII, but not LIF, is able to support the maintenance and proliferation in culture of pluripotent cells derived from primitive ectoderm formed in vitro or during embryonic development. This distinguishes primitive ectoderm and inner cell mass (ICM) on the basis of cytokine responsiveness and validates the biological activity proposed for factors within MEDII in primitive ectoderm establishment and maintenance. Further, it potentially provides an alternative technology for the isolation of pluripotent cells from the mammalian embryo.