The blood-brain barrier (BBB) is composed of tightly bound endothelial cells (ECs) and perivascular astrocytes that regulate central nervous system (CNS) homeostasis. We showed that astrocytes ...secrete Sonic hedgehog and that BBB ECs express Hedgehog (Hh) receptors, which together promote BBB formation and integrity during embryonic development and adulthood. Using pharmacological inhibition and genetic inactivation of the Hh signaling pathway in ECs, we also demonstrated a critical role of the Hh pathway in promoting the immune quiescence of BBB ECs by decreasing the expression of proinflammatory mediators and the adhesion and migration of leukocytes, in vivo and in vitro. Overall, the Hh pathway provides a barrier-promoting effect and an endogenous anti-inflammatory balance to CNS-directed immune attacks, as occurs in multiple sclerosis.
Growing evidence supports a role for IL-1 in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE), but how it impacts neuroinflammation is poorly understood. We show that ...susceptibility to EAE requires activation of IL-1R1 on radiation-resistant cells via IL-1β secreted by bone marrow-derived cells. Neutrophils and monocyte-derived macrophages (MDMs) are the main source of IL-1β and produce this cytokine as a result of their transmigration across the inflamed blood-spinal cord barrier. IL-1R1 expression in the spinal cord is found in endothelial cells (ECs) of the pial venous plexus. Accordingly, leukocyte infiltration at EAE onset is restricted to IL-1R1(+) subpial and subarachnoid vessels. In response to IL-1β, primary cultures of central nervous system ECs produce GM-CSF, G-CSF, IL-6, Cxcl1, and Cxcl2. Initiation of EAE or subdural injection of IL-1β induces a similar cytokine/chemokine signature in spinal cord vessels. Furthermore, the transfer of Gr1(+) cells on the spinal cord is sufficient to induce illness in EAE-resistant IL-1β knockout (KO) mice. Notably, transfer of Gr1(+) cells isolated from C57BL/6 mice induce massive recruitment of recipient myeloid cells compared with cells from IL-1β KO donors, and this recruitment translates into more severe paralysis. These findings suggest that an IL-1β-dependent paracrine loop between infiltrated neutrophils/MDMs and ECs drives neuroinflammation.
Women develop certain autoimmune diseases more often than men. It has been hypothesized that this may relate to the development of more robust T-helper (Th)1 responses in women. To test whether women ...exhibit a Th1 bias, we isolated naïve cluster of differentiation (CD)4 ⁺ T cells from peripheral blood of healthy women and men and measured the proliferation and cytokine production by these cells in response to submaximal amounts of anti-CD3 and anti-CD28. We observed that CD4 ⁺ T cells from women produced higher levels of IFNγ as well as tended to proliferate more than male CD4 ⁺ T cells. Intriguingly, male CD4 ⁺ T cells instead had a predilection toward IL-17A production. This sex dichotomy in Th cytokine production was found to be even more striking in the Swiss/Jackson Laboratory (SJL) mouse. Studies in mice and humans indicated that the sexual dimorphism in Th1 and Th17 cytokine production was dependent on the androgen status and the T-cell expression of peroxisome proliferator activated receptor (PPAR)α and PPARγ. Androgens increased PPARα and decreased PPARγ expression by human CD4 ⁺ T cells. PPARα siRNA-mediated knockdown had the effect of increasing IFNγ by male CD4 ⁺ T cells, while transfection of CD4 ⁺ T cells with PPARγ siRNAs increased IL-17A production uniquely by female T cells. Together, our observations indicate that human T cells exhibit a sex difference in the production of IFNγ and IL-17A that may be driven by expressions of PPARα and PPARγ.
Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disorder of the central nervous system (CNS). Current therapies mainly target inflammatory processes during acute stages, but effective ...treatments for progressive MS are limited. In this context, astrocytes have gained increasing attention as they have the capacity to drive, but also suppress tissue-degeneration. Here we show that astrocytes upregulate the immunomodulatory checkpoint molecule PD-L1 during acute autoimmune CNS inflammation in response to aryl hydrocarbon receptor and interferon signaling. Using CRISPR-Cas9 genetic perturbation in combination with small-molecule and antibody-mediated inhibition of PD-L1 and PD-1 both in vivo and in vitro, we demonstrate that astrocytic PD-L1 and its interaction with microglial PD-1 is required for the attenuation of autoimmune CNS inflammation in acute and progressive stages in a mouse model of MS. Our findings suggest the glial PD-L1/PD-1 axis as a potential therapeutic target for both acute and progressive MS stages.
Neuroimmune dysregulation is implicated in neuropsychiatric disorders including schizophrenia. As the blood-brain barrier is the immunological interface between the brain and the periphery, we ...investigated whether this vascular phenotype is intrinsically compromised in the most common genetic risk factor for schizophrenia, the 22q11.2 deletion syndrome (22qDS). Blood-brain barrier like endothelium differentiated from human 22qDS+schizophrenia-induced pluripotent stem cells exhibited impaired barrier integrity, a phenotype substantiated in a mouse model of 22qDS. The proinflammatory intercellular adhesion molecule-1 was upregulated in 22qDS+schizophrenia-induced blood-brain barrier and in 22qDS mice, indicating compromise of the blood-brain barrier immune privilege. This immune imbalance resulted in increased migration/activation of leucocytes crossing the 22qDS+schizophrenia blood-brain barrier. We also found heightened astrocyte activation in murine 22qDS, suggesting that the blood-brain barrier promotes astrocyte-mediated neuroinflammation. Finally, we substantiated these findings in post-mortem 22qDS brain tissue. Overall, the barrier-promoting and immune privilege properties of the 22qDS blood-brain barrier are compromised, and this might increase the risk for neuropsychiatric disease.
Objective
To define changes in phenotype and functional responses of reconstituting T cells in patients with aggressive multiple sclerosis (MS) treated with ablative chemotherapy and autologous ...hematopoietic stem cell transplantation (HSCT).
Methods
Clinical and brain magnetic resonance imaging measures of disease activity were monitored serially in patients participating in the Canadian MS HSCT Study. Reconstitution kinetics of immune‐cell subsets were determined by flow cytometry, whereas thymic function was assessed using T‐cell receptor excision circle analyses as well as flow cytometry measurements of CD31+ recent thymic emigrants (RTEs). Functional assays were performed to track central nervous system–autoreactive antigen‐specific T‐cell responses, and the relative capacity to generate Th1, Th17, or Th1/17 T‐cell responses.
Results
Complete abrogation of new clinical relapses and new focal inflammatory brain lesions throughout the 2 years of immune monitoring following treatment was associated with sustained decrease in naive T cells, in spite of restoration of both thymic function and release of RTEs during reconstitution. Re‐emergence as well as in vivo expansion of autoreactive T cells to multiple myelin targets was evident in all patients studied. The reconstituted myelin‐specific T cells exhibited the same Th1 and Th2 responses as preablation myelin‐reactive T cells. In contrast, the post‐therapy T‐cell repertoire exhibited a significantly diminished capacity for Th17 responses.
Interpretation
Our results indicate that diminished Th17 and Th1/17 responses, rather than Th1 responses, are particularly relevant to the abrogation of new relapsing disease activity observed in this cohort of patients with aggressive MS following chemoablation and HSCT. ANN NEUROL 2013;73:341–354
Trafficking of antigen-presenting cells into the CNS is essential for lymphocyte reactivation within the CNS compartment. Although perivascular dendritic cells found in inflammatory lesions are ...reported to polarize naive CD4+ T lymphocytes into interleukin-17-secreting-cells, the origin of those antigen-presenting cells remains controversial. We demonstrate that a subset of CD14+ monocytes migrate across the inflamed human blood–brain barrier (BBB) and differentiate into CD83+CD209+ dendritic cells under the influence of BBB-secreted transforming growth factor-β and granulocyte-macrophage colony-stimulating factor. We also demonstrate that these dendritic cells secrete interleukin-12p70, transforming growth factor-β and interleukin-6 and promote the proliferation and expansion of distinct populations of interferon-γ-secreting Th1 and interleukin-17-secreting Th17 CD4+ T lymphocytes. We further confirmed the abundance of such dendritic cells in situ, closely associated with microvascular BBB-endothelial cells within acute multiple sclerosis lesions, as well as a significant number of CD4+ interleukin-17+ T lymphocytes in the perivascular infiltrate. Our data support the notion that functional perivascular myeloid CNS dendritic cells arise as a consequence of migration of CD14+ monocytes across the human BBB, through the concerted actions of BBB-secreted transforming growth factor-β and granulocyte-macrophage colony-stimulating factor.
Objective:
Blood‐derived myeloid antigen‐presenting cells (APCs) account for a significant proportion of the leukocytes found within lesions of multiple sclerosis (MS) and experimental allergic ...encephalomyelitis (EAE). These APCs along with activated microglia are thought to be pivotal in the initiation of the central nervous system (CNS)‐targeted immune response in MS and EAE. However, the exact molecules that direct the migration of myeloid cells from the periphery across the blood–brain barrier (BBB) remain largely unknown.
Methods:
We identified Ninjurin‐1 in a proteomic screen of human BBB endothelial cells (ECs). We assessed the expression of Ninjurin‐1 by BBB‐ECs and immune cells, and we determined the role of Ninjurin‐1 in immune cell migration to the CNS in vivo in EAE mice.
Results:
Ninjurin‐1 was found to be weakly expressed in the healthy human and mouse CNS but upregulated on BBB‐ECs and on infiltrating APCs during the course of EAE and in active MS lesions. In human peripheral blood, Ninjurin‐1 was predominantly expressed by monocytes, whereas it was barely detectable on T and B lymphocytes. Moreover, Ninjurin‐1 neutralization specifically abrogated the adhesion and migration of human monocytes across BBB‐ECs, without affecting lymphocyte recruitment. Finally, Ninjurin‐1 blockade reduced clinical disease activity and histopathological indices of EAE and decreased infiltration of macrophages, dendritic cells, and APCs into the CNS.
Interpretation:
Our study uncovers an important cell‐specific role for Ninjurin‐1 in the transmigration of inflammatory APCs across the BBB and further emphasizes the importance of myeloid cell recruitment during the development of neuroinflammatory lesions.ANN NEUROL 2011
Abstract In multiple sclerosis (MS), there is a growing interest in inhibiting the pro-inflammatory effects of granulocyte-macrophage colony-stimulating factor (GM-CSF). We sought to evaluate the ...therapeutic potential and underlying mechanisms of GM-CSF receptor alpha (Rα) blockade in animal models of MS. We show that GM-CSF signaling inhibition at peak of chronic experimental autoimmune encephalomyelitis (EAE) results in amelioration of disease progression. Similarly, GM-CSF Rα blockade in relapsing-remitting (RR)-EAE model prevented disease relapses and inhibited T cell responses specific for both the inducing and spread myelin peptides, while reducing activation of mDCs and inflammatory monocytes. In situ immunostaining of lesions from human secondary progressive MS (SPMS), but not primary progressive MS patients shows extensive recruitment of GM-CSF Rα+ myeloid cells. Collectively, this study reveals a pivotal role of GM-CSF in disease relapses and the benefit of GM-CSF Rα blockade as a potential novel therapeutic approach for treatment of RRMS and SPMS.
is an ancient mineral-herbal mixture containing β-HgS in Tibetan medicine. It is used to treat nervous system diseases, similar to Chinese medicine cinnabar and Indian Ayurveda medicine
. However, ...one of the key problems faced by
is that its indications are ambiguous. Our previous study found that
exhibited the activity of ameliorating depressive-like behaviors in a chronic mild stress model. However, due to the inherent limitations of animal models in simulating human disease, clear results often require more than one model for confirmation.
Therefore, another depression model, chronic restraint stressed (CRS) mice, was used to validate the antidepression effect of
. Prophylactic treatment was conducted for 21 consecutive days while mice were subjected to chronic restraint stress.
It was observed that
and β-HgS alleviated anhedonia, behavioral despair, stereotype behavior, and reduced exploratory and spontaneous movement in CRS mice.
and β-HgS also reversed the increases of stress hormone corticosterone (Cort) in serum and pro-inflammatory cytokines in serum and brain, and increased the serotonin in cortex in CRS mice, with positive dose-effect relationship. The number of Ki67-positive cells in the dentate gyrus and the level of brain-derived neurotrophic factor (BDNF) in the hippocampus were slightly elevated in CRS mice treated with
; however, there was no statistically significant difference. Although
increased the total Hg concentration in main organs, the levels remained below those needed to result in observed adverse effect, at least for kidney and liver; and
showed no observed adverse effect on the brain histopathology, the cell proliferation in dentate gyrus, as well as the hippocampal and cortical organ coefficients.
exhibited the alleviation of depressive-like behaviors in CRS mice, accompanying with ameliorating stress hormone, peripherical and cerebral inflammation, and monoamine neurotransmitter.
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