Delta-like ligand 4 regulates central nervous system T cell accumulation during experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is a CD4(+) T cell-mediated inflammatory demyelinating disease of the CNS that serves as a model for multiple sclerosis. Notch receptor signaling in T lymphocytes has been shown to regulate thymic selection and peripheral differentiation. In the current study, we hypothesized that Notch ligand-receptor interaction affects EAE development by regulating encephalitogenic T cell trafficking. We demonstrate that CNS-infiltrating myeloid dendritic cells, macrophages, and resident microglia expressed Delta-like ligand 4 (DLL4) after EAE induction. Treatment of mice with a DLL4-specific blocking Ab significantly inhibited the development of clinical disease induced by active priming. Furthermore, the treatment resulted in decreased CNS accumulation of mononuclear cells in the CNS. Anti-DLL4 treatment did not significantly alter development of effector cytokine expression by Ag-specific T cells. In contrast, anti-DLL4 treatment reduced T cell mRNA and functional cell surface expression of the chemokine receptors CCR2 and CCR6. Adoptive transfer of Ag-specific T cells to mice treated with anti-DLL4 resulted in decreased clinical severity and diminished Ag-specific CD4(+) T cell accumulation in the CNS. These results suggest a role for DLL4 regulation of EAE pathogenesis through modulation of T cell chemokine receptor expression and migration to the CNS.

Clinical support for the off-shift nurse and the graduate nurse: the clinical rock stars.

Turnover of medical-surgical nurses can be distressing and costly Establishment of the clinical resource specialist role can provide a valuable resource to off-shift RNs and have a positive impact on job satisfaction.

Molecular mechanisms of environmental enrichment: impairments in Akt/GSK3ß, neurotrophin-3 and CREB signaling.

Experience of mice in a complex environment enhances neurogenesis and synaptic plasticity in the hippocampus of wild type and transgenic mice harboring familial Alzheimer's disease (FAD)-linked APPswe/PS1ΔE9. In FAD mice, this experience also reduces levels of tau hyperphosphorylation and oligomeric ß-amyloid. Although environmental enrichment has significant effects on brain plasticity and neuropathology, the molecular mechanisms underlying these effects are unknown. Here we show that environmental enrichment upregulates the Akt pathway, leading to the downregulation of glycogen synthase kinase 3ß (GSK3ß), in wild type but not FAD mice. Several neurotrophic signaling pathways are activated in the hippocampus of both wild type and FAD mice, including brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF), and this increase is accompanied by the upregulation of the BDNF receptor, tyrosine kinase B (TrkB). Interestingly, neurotrophin-3 (NT-3) is upregulated in the brains of wild type mice but not FAD mice, while insulin growth factor-1 (IGF-1) is upregulated exclusively in the brains of FAD mice. Upregulation of neurotrophins is accompanied by the increase of N-Methyl-D-aspartic acid (NMDA) receptors in the hippocampus following environmental enrichment. Most importantly, we observed a significant increase in levels of cAMP response element- binding (CREB) transcripts in the hippocampus of wild type and FAD mice following environmental enrichment. However, CREB phosphorylation, a critical step for the initiation of learning and memory-required gene transcription, takes place in the hippocampus of wild type but not of FAD mice. These results suggest that experience of wild type mice in a complex environmental upregulates critical signaling that play a major role in learning and memory in the hippocampus. However, in FAD mice, some of these pathways are impaired and cannot be rescued by environmental enrichment.

CCL22 regulates experimental autoimmune encephalomyelitis by controlling inflammatory macrophage accumulation and effector function.

EAE is a demyelinating disease of the CNS and serves as a mouse model of MS. Expression of CCL22 in the draining LNs and spinal cord correlated with the onset of clinical EAE development and remained elevated. Administration of anti-CCL22 at the time of autoantigen immunization delayed the initiation of clinical disease and dampened the severity of peak initial disease and relapses. Reduced EAE severity correlated with the reduction of pathology and leukocytes in the CNS, particularly, activated CD11b+Ly6C(hi) macrophages. There were no differences in effector T cell-proliferative responses or effector T cell IFN-γ or IL-17 responses. However, treatment at the onset of disease did not reduce disease progression. Treatment of adoptive T cell transfer recipient mice with anti-CCL22 resulted in decreased clinical disease development accompanied by a decrease in CNS accumulation of CD11b+Ly6C(hi) macrophages. Neutralization of CCL22 resulted in a macrophage population whose effector cytokine expression consisted of decreased TNF and increased IL-10, a phenotype more consistent with M2 macrophages. This was corroborated by in vitro cultures of macrophages with CCL22. These results suggest that CCL22 functions to regulate development of EAE through macrophage chemoattraction and effector function.