Project description:Theiler’s murine encephalomyelitis virus (TMEV) induces different diseases in the central nervous system (CNS) and heart, depending on the mouse strains and time course, where cytokines play a key role for viral clearance and immune-mediated pathology (immunopathology). In SJL/J mice, TMEV infection causes chronic TMEV-induced demyelinating disease (TMEV-IDD) in the spinal cord around 1 month post infection (p.i.). Unlike other immunopathology models, both pro-inflammatory and anti-inflammatory cytokines can play dual roles in TMEV-IDD. Pro-inflammatory cytokines play a beneficial role in viral clearance while they also play a detrimental role in immune-mediated demyelination. Anti-inflammatory cytokines suppress not only protective anti-viral immune responses but also detrimental autoreactive immune responses. On the other hand, in C3H mice, TMEV infection induces a non-CNS disease, myocarditis, with three phases: phase I, viral pathology with interferon and chemokine responses; phase II, immunopathology mediated by acquired immune responses; and phase III, cardiac fibrosis. Although the precise mechanism how a single virus, TMEV, induces the distinct diseases in different organs is unclear, principal component analysis (PCA) of transcriptome data allows us to identify the key factors contributing to distinct immunopathology. The PCA demonstrated that in vitro infection of a cardiomyocyte cell line could reproduce the transcriptome profile of phase I in TMEV-induced myocarditis; distinct interferon/chemokine-related responses were induced in vitro in infected cardiomyocytes, but not in infected neuronal cells. In addition, the PCA of in vivo CNS transcriptome data showed that decreased lymphatic marker expression was associated with inflammation in TMEV infection. Here, dysfunction of lymphatic vessels may contribute to immunopathology by delaying clearance of cytokines and immune cells from the inflammatory site, although this might confine the virus at the site, preventing virus spread via lymphatic vessels. On the other hand, in the heart, dysfunction of lymphatics was associated with reduced lymphatic muscle contractility by pro-inflammatory cytokines. Therefore, TMEV infection could induce different cytokine expressions as well as lymphatic vessel dysfunction by the distinct mechanism between the CNS and heart, which might contribute to organ-specific immunopathology.

Project description:The lymphatic vascular system plays important roles in the maintenance of interstitial fluid pressure, the afferent immune response and the absorption of dietary lipids. However, the molecular mechanisms that control lymphatic vessel network maturation and function remain largely unknown. To identify novel players in lymphatic vessel function, we isolated pure populations of lymphatic and blood vascular endothelial cells from mouse intestine using fluorescence-activated high-speed cell sorting and performed transcriptional profiling. We found that the axonal guidance molecules semaphorin 3A (Sema3A) and Sema3D were specifically expressed by lymphatic vessels. Quantitative PCR of ex vivo isolated cells and immunohistochemical analysis confirmed these results. Importantly, we found that the semaphorin receptor neuropilin-1 (Nrp-1) is expressed on the valves of collecting lymphatic vessels. Treatment of mice in utero (E12.5-E16.5) with an antibody that blocks Sema3A binding to Nrp-1, but not with an antibody that blocks VEGFA binding to Nrp-1, resulted in abnormal development of collecting lymphatic vessels and valves, and aberrant smooth muscle cell coverage. Conversely, Sema3A-deficient mice displayed branching defects of collecting lymphatic vessels as well as impaired valve development. Together, these results reveal an unanticipated role of Sema3A/Nrp-1 signaling in the maturation of the lymphatic vascular network. Colon single-cell suspensions were prepared by a fast protocol that minimizes the RNA degradation. Fluorescence-activated cell sorting (FACS) was used to sort blood vascular endothelial cells (BEC) and lymphatic endothelial cells (LEC). 4 animal-matched pairs of LEC and BEC were chosen based on the quality of extracted and amplified material to provide homogenous groups of biological replicates. This gave 8 samples to analyze. Samples present LEC and BEC isolated from 4 healthy normal mice. The 4 mice used present the 4 biological replicates.

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The axillary lymphoid organ - an external, experimentally accessible immune organ in the zebrafish

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