Recent studies demonstrated that primary immune responses can be induced within the brain depending on vessel-associated cells expressing markers of dendritic cells (DC). Using mice transcribing the green fluorescent protein (GFP) under the promoter of the DC marker CD11c, we determined the distribution, phenotype, and source of CD11c+ cells in non-diseased brains. Predilection areas of multiple sclerosis (MS) lesions (periventricular area, adjacent fibre tracts, and optical nerve) were preferentially populated by CD11c+ cells. Most CD11c+ cells were located within the juxtavascular parenchyma rather than the perivascular spaces. Virtually all CD11c+ cells co-expressed ionized calcium-binding adaptor molecule 1 (IBA-1), CD11b, while detectable levels of major histocompatibility complex II (MHC-II) in non-diseased mice was restricted to CD11c+ cells of the choroid plexus. Cellular processes project into the glia limitans which may allow transport and/or presentation of intraparenchymal antigens to extravasated T cells in perivascular spaces. In chimeric mice bearing CD11c-GFP bone marrow, fluorescent cells appeared in the CNS between 8 and 12 weeks after transplantation. In organotypic slice cultures from CD11c-GFP mice, the number of fluorescent cells strongly increased within 72 h. Strikingly, using anti-CD209, an established marker for human DC, a similar population was detected in human brains. Thus, we show for the first time that CD11c+ cells can not only be recruited from the blood into the parenchyma, but also develop from an intraneural precursor in situ. Dysbalance in their recruitment/development may be an initial step in the pathogenesis of chronic (autoimmune) neuroinflammatory diseases such as MS.
"In previous studies Greter et al . demonstrated the exis - tence of vessel - associated CD11c - positive cells , which appeared to be located in pv spaces ( Greter et al . , 2005 ) . Fur - thermore , using fluorescence and electron microscopy our group identified an intraparenchymal population of CD11c - positive cells ( Prodinger et al . , 2011 ) , which express the mac - rophage marker IBA - 1 and CD11b . In continuation of our previous work , the current study demonstrates that cells expressing a microglial phenotype ( CD45 int , CD11b ) contain a distinct subpopulation expressing CD11c . This is in line with previous studies confirming the existence of CD11c - positive cell"
"More interestingly, they also described a population of cells expressing the DC marker CD209 within the CNS parenchyma in close vicinity to blood vessels. Closer analysis revealed that these cells interdigitated with astroglial endfeet and integrated into the glia limitans, where they were presumably poised for interacting with cells in the perivascular space (Prodinger et al., 2011). Indeed, these cells may play an important role as tissue APCs during neuroinflammation; however, their relatively limited abundance together with data showing that MHCII expression on infiltrating cells is required for EAE (Greter et al., 2005) suggests that other APCs strongly contribute to T cell restimulation. "
[Show abstract][Hide abstract] ABSTRACT: Evidence from experimental autoimmune encephalomyelitis (EAE) suggests that CNS-infiltrating dendritic cells (DCs) are crucial for restimulation of coinfiltrating T cells. Here we systematically quantified and visualized the distribution and interaction of CNS DCs and T cells during EAE. We report marked periventricular accumulation of DCs and myelin-specific T cells during EAE disease onset prior to accumulation in the spinal cord, indicating that the choroid plexus-CSF axis is a CNS entry portal. Moreover, despite emphasis on spinal cord inflammation in EAE and in correspondence with MS pathology, inflammatory lesions containing interacting DCs and T cells are present in specific brain regions.
Journal of Neuroimmunology 09/2014; 277(1-2). DOI:10.1016/j.jneuroim.2014.09.016 · 2.47 Impact Factor
"We and others have previously reported that pFTY720 promotes remyelination and attenuates demyelination in organotypic slice cultures, which contain immune cells –. In these studies LPC was used to induce demyelination, however, a concern using this agent is that the mechanism by which LPC induces demyelination, in vitro or in vivo, is not fully clear. "
[Show abstract][Hide abstract] ABSTRACT: The family of sphingosine-1-phosphate receptors (S1PRs) is G-protein-coupled, comprised of subtypes S1PR1-S1PR5 and activated by the endogenous ligand S1P. The phosphorylated version of Fingolimod (pFTY720), an oral therapy for multiple sclerosis (MS), induces S1PR1 internalisation in T cells, subsequent insensitivity to S1P gradients and sequestering of these cells within lymphoid organs, thus limiting immune response. S1PRs are also expressed in neuronal and glial cells where pFTY720 is suggested to directly protect against lysolecithin-induced deficits in myelination state in organotypic cerebellar slices. Of note, the effect of pFTY720 on immune cells already migrated into the CNS, prior to treatment, has not been well established. We have previously found that organotypic slice cultures do contain immune cells, which, in principle, could also be regulated by pFTY720 to maintain levels of myelin. Here, a mouse organotypic cerebellar slice and splenocyte co-culture model was thus used to investigate the effects of pFTY720 on splenocyte-induced demyelination. Spleen cells isolated from myelin oligodendrocyte glycoprotein immunised mice (MOG-splenocytes) or from 2D2 transgenic mice (2D2-splenocytes) both induced demyelination when co-cultured with mouse organotypic cerebellar slices, to a similar extent as lysolecithin. As expected, in vivo treatment of MOG-immunised mice with FTY720 inhibited demyelination induced by MOG-splenocytes. Importantly, in vitro treatment of MOG- and 2D2-splenocytes with pFTY720 also attenuated demyelination caused by these cells. In addition, while in vitro treatment of 2D2-splenocytes with pFTY720 did not alter cell phenotype, pFTY720 inhibited the release of the pro-inflammatory cytokines such as interferon gamma (IFNγ) and interleukin 6 (IL6) from these cells. This work suggests that treatment of splenocytes by pFTY720 attenuates demyelination and reduces pro-inflammatory cytokine release, which likely contributes to enhanced myelination state induced by pFTY720 in organotypic cerebellar slices.
PLoS ONE 06/2014; 9(6):e99444. DOI:10.1371/journal.pone.0099444 · 3.23 Impact Factor
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