Transcriptomics Reveal the Survival Strategies of Enterococcus mundtii in the Gut of Spodoptera littoralis.

The complex interaction between a higher organism and its resident gut flora is a subject of immense interest in the field of symbiosis. Many insects harbor a complex community of microorganisms in their gut. Larvae of Spodoptera littoralis, a lepidopteran pest, house a bacterial community that varies both spatially (along the length of the gut) and temporally (during the insect's life cycle). To monitor the rapid adaptation of microbes to conditions in the gut, a GFP-tagged reporter strain of E. mundtii, a major player in the gut community, was constructed. After early-instar S. littoralis larvae were fed with the tagged microbes, these were recovered from the larval fore- and hindgut by flow cytometry. The fluorescent reporter confirmed the persistence of E. mundtii in the gut. RNA-sequencing of the sorted bacteria highlighted various strategies of the symbiont's survival, including upregulated pathways for tolerating alkaline stress, forming biofilms and two-component signaling systems for quorum sensing, and resisting oxidative stress. Although these symbionts depend on the host for amino acid and fatty acids, differential regulation among various metabolic pathways points to an enriched lysine synthesis pathway of E. mundtii in the hindgut of the larvae.

Effect of skilled reaching training and enriched environment on generation of oligodendrocytes in the adult sensorimotor cortex and corpus callosum.

BACKGROUND: Increased motor activity or social interactions through enriched environment are strong stimulators of grey and white matter plasticity in the adult rodent brain. In the present study we evaluated whether specific reaching training of the dominant forelimb (RT) and stimulation of unspecific motor activity through enriched environment (EE) influence the generation of distinct oligodendrocyte subpopulations in the sensorimotor cortex and corpus callosum of the adult rat brain. Animals were placed in three different housing conditions: one group was transferred to an EE, a second group received daily RT, whereas a third group remained in the standard cage. Bromodeoxyuridine (BrdU) was applied at days 2-6 after start of experiments and animals were allowed to survive for 10 and 42 days. RESULTS: Enriched environment and daily reaching training of the dominant forelimb significantly increased the number of newly differentiated GSTπ+ oligodendrocytes at day 10 and newly differentiated CNPase+ oligodendrocytes in the sensorimotor cortex at day 42. The myelin level as measured by CNPase expression was increased in the frontal cortex at day 42. Distribution of newly differentiated NG2+ subpopulations changed between 10 and 42 days with an increase of GSTπ+ subtypes and a decrease of NG2+ cells in the sensorimotor cortex and corpus callosum. Analysis of neuronal marker doublecortin (DCX) showed that more than half of NG2+ cells express DCX in the cortex. The number of new DCX+NG2+ cells was reduced by EE at day 10. CONCLUSIONS: Our results indicate for the first time that specific and unspecific motor training conditions differentially alter the process of differentiation from oligodendrocyte subpopulations, in particular NG2+DCX+ cells, in the sensorimotor cortex and corpus callosum.

Caspase-3 and caspase-6 cleave STAT1 in leukemic cells.

Signal Transducer and Activator of Transcription-1 (STAT1) is phosphorylated upon interferon (IFN) stimulation, which can restrict cell proliferation and survival. Nevertheless, in some cancers STAT1 can act in an anti-apoptotic manner. Moreover, certain malignancies are characterized by the overexpression and constitutive activation of STAT1. Here, we demonstrate that the treatment of transformed hematopoietic cells with epigenetic drugs belonging to the class of histone deacetylase inhibitors (HDACi) leads to the cleavage of STAT1 at multiple sites by caspase-3 and caspase-6. This process does not occur in solid tumor cells, normal hematopoietic cells, and leukemic cells that underwent granulocytic or monocytic differentiation. STAT1 cleavage was studied under cell free conditions with purified STAT1 and a set of candidate caspases as well as with mass spectrometry. These assays indicate that unmodified STAT1 is cleaved at multiple sites by caspase-3 and caspase-6. Our study shows that STAT1 is targeted by caspases in malignant undifferentiated hematopoietic cells. This observation may provide an explanation for the selective toxicity of HDACi against rapidly proliferating leukemic cells.

Immunopathogenesis of dilated cardiomyopathy. Evidence for the role of TH2-type CD4+T lymphocytes and association with myocardial HLA-DR expression.

BACKGROUND: An immunological pathogenesis underlying dilated cardiomyopathy and myocarditis has been suggested on the basis of the subtype of lymphocyte infiltrates and the degree of HLA expression in cardiac tissue. In the present study, we investigated the relation between the peripheral CD4+T-cell subset and the degree of HLA expression in the heart. METHODS: Fifty-four patients with heart insufficiency included in the study were biopsied after coronary heart disease had been excluded. Immunohistological staining of the left ventricular tissue were performed employing anti-CD3, -CD4, -CD8, -CD14, and HLA-DR monoclonal antibodies. Intracellular expression of IL-2, IL-4, IL-5, IFN-gamma, and TNF-alpha in peripheral CD4+T lymphocytes was determined using flow cytometry. The severity of heart insufficiency was determined by measurement of brain natriuretic peptide (BNP) and the NYHA class. On the basis of HLA expression in the heart, the patients were divided into three groups: Group I (mild-to-none), Group II (moderate), and Group III (strong-to-very strong). RESULTS: Of the 54 patients included in this study, 33 (61%) patients were diagnosed as having idiopathic dilated cardiomyopathy and 10 (18.5%) borderline or healing myocarditis according to the Dallas criteria. Both patient groups were found in all three HLA-DR groups. There was no difference in BNP level or NYHA class between the three groups. However, a significant difference in the proportion of CD4+T lymphocytes producing IL-2 (39.2 versus 21.8%), IFN-gamma (19.5 versus 7.8%), and TNF-alpha (35.8 versus 16.1%) between Groups I and III could be detected, whereas the distribution of IL-4 and IL-5 producing CD4+T lymphocytes was similar. The myocardium of Group III patients exhibited a significant higher number of CD3+T cells (11.4 versus 4.3 per mm2) and CD4+T cells (4.7 versus 0.8 per mm2) compared to Group I patients, while no difference existed with respect to CD8+T cells. CONCLUSION: High myocardial expression of the HLA-DR antigen is associated with an increase of peripheral-blood CD4+T lymphocytes expressing cytokines of the TH2 subset. The degree of HLA-DR expression is not associated with the degree of heart insufficiency or underlying diagnosis, but correlates with an increase of activated T cells in the myocardium. The data suggest that CD4+T lymphocytes infiltrating cardiac tissue may play a pathogenic role in dilated cardiomyopathy.