FoxP3+ regulatory T cells determine disease severity in rodent models of inflammatory neuropathies.

Inflammatory neuropathies represent disabling human autoimmune disorders with considerable disease variability. Animal models provide insights into defined aspects of their disease pathogenesis. Forkhead box P3 (FoxP3)+ regulatory T lymphocytes (Treg) are anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders.

Enhanced in vivo efficacy of a type I interferon superagonist with extended plasma half-life in a mouse model of multiple sclerosis.

IFNβ is a common therapeutic option to treat multiple sclerosis. It is unique among the family of type I IFNs in that it binds to the interferon receptors with high affinity, conferring exceptional biological properties. We have previously reported the generation of an interferon superagonist (dubbed YNSα8) that is built on the backbone of a low affinity IFNα but modified to exhibit higher receptor affinity than even for IFNβ.

Bridging the species divide: transgenic mice humanized for type-I interferon response.

We have generated transgenic mice that harbor humanized type I interferon receptors (IFNARs) enabling the study of type I human interferons (Hu-IFN-Is) in mice. These "HyBNAR" (Hybrid IFNAR) mice encode transgenic variants of IFNAR1 and IFNAR2 with the human extracellular domains being fused to transmembrane and cytoplasmic segments of mouse sequence. B16F1 mouse melanoma cells harboring the HyBNAR construct specifically bound Hu-IFN-Is and were rendered sensitive to Hu-IFN-I stimulated anti-proliferation, STAT1 activation and activation of a prototypical IFN-I response gene (MX2).

Immune modulation by Lacto-N-fucopentaose III in experimental autoimmune encephalomyelitis.

Parasitic infections frequently lead to immune deviation or suppression. However, the application of specific parasitic molecules in regulating autoimmune responses remains to be explored. Here we report on the immune modulatory function of Lacto-N-fucopentaose III (LNFPIII), a schistosome glycan, in an animal model for multiple sclerosis.

Regulatory T cells exhibit enhanced migratory characteristics, a feature impaired in patients with multiple sclerosis.

Migration of immune cells characterizes inflammation and plays a key role in autoimmune diseases such as MS. CD4(+)Foxp3(+) regulatory T cells (Treg) have the potential to dampen immune responses but show functional impairment in patients with MS. We here show that murine Treg exhibit higher constitutive cell motility in horizontal migration on laminin, surpass non-Treg in transwell assays through microporous membranes as well as across primary brain endothelium and are present in the naïve CNS to a significantly higher extent compared to spleen, lymph nodes and blood.

An imbalance of two functionally and phenotypically different subsets of plasmacytoid dendritic cells characterizes the dysfunctional immune regulation in multiple sclerosis.

Plasmacytoid dendritic cells (pDCs) are instrumental in peripheral T cell tolerance and innate immunity. How pDCs control peripheral immunetolerance and local parenchymal immune response and contribute to the altered immunoregulation in autoimmune disorders in humans is poorly understood. Based on their surface markers, cytokine production, and ability to prime naive allogenic T cells, we found that purified BDCA-2(+)BDCA-4(+) pDCs consist of at least two separate populations, which differed in their response to oligodeoxynucleotides and IFNs (IFN-beta), and differently induced IL-17- or IL-10-producing T cells.

Using carbon magnetic nanoparticles to target, track, and manipulate dendritic cells.

Dendritic cells (DCs) are crucial in the initiation of immune responses and are primary targets in vaccination. Here, we describe fluorescent, carbon magnetic nanoparticles (CMNPs) within the 20-80 nm size range that are non-toxic and preferentially endocytosed by DCs. These attributes allow for DC tracing in vitro, ex vivo and in vivo, by both fluorescence and MRI.

The role of dendritic cells in CNS autoimmunity.

Multiple sclerosis (MS) is a chronic immune-mediated, central nervous system (CNS) demyelinating disease. Clinical and histopathological features suggest an inflammatory etiology involving resident CNS innate cells as well as invading adaptive immune cells. Encephalitogenic myelin-reactive T cells have been implicated in the initiation of an inflammatory cascade, eventually resulting in demyelination and axonal damage (the histological hallmarks of MS).

Active immunization induces toxicity of diphtheria toxin in diphtheria resistant mice--implications for neuroinflammatory models.

Cell-type specific expression of the human diphtheria toxin receptor in generally toxin resistant mice represents an innovative approach for the selective depletion of pre-defined cell populations. We demonstrate that in wildtype mice diphtheria toxin--in concentrations otherwise well tolerated--is highly toxic and lethal together with active immunization irrespective of the immunogenic peptide applied. We found increased lung cellularity as only pathological abnormality.

The same well-characterized T cell epitope SIINFEKL expressed in the context of a cytoplasmic or secreted protein in BCG induces different CD8+ T cell responses.

Mycobacterium bovis BCG is still the most widely used vaccine against tuberculosis and CD8(+) T cells play important roles in fighting infection. We investigated how well antigen is processed and presented to CD8(+) T cells using the same well-characterized CD8(+) T cell epitope SIINFEKL expressed in either a cytoplasmic (GFP-OVA) or secreted (85B-OVA) context from BCG. We report that secreted SIINFEKL from 85B-OVA BCG is presented better than cytoplasmic SIINFEKL expressed by GFP-OVA BCG.

Specific central nervous system recruitment of HLA-G(+) regulatory T cells in multiple sclerosis.

Objective: We have recently described a novel population of natural regulatory T cells (T(reg)) that are characterized by the expression of HLA-G and may be found at sites of tissue inflammation (HLA-G(pos) T(reg)). Here we studied the role of these cells in multiple sclerosis (MS), a prototypic autoimmune inflammatory disorder of the central nervous system (CNS).

Methods: Sixty-four patients with different types of MS, 9 patients with other neurological diseases, and 20 healthy donors were included in this study.

The level of B7 homologue 1 expression on brain DC is decisive for CD8 Treg cell recruitment into the CNS during EAE.

DC in the CNS have emerged as the major rate-limiting factor for immune invasion and subsequent neuroinflammation during EAE. The mechanism of how this is regulated by brain-localized DC remains unknown. Here, we describe the ability of brain-localized DC expressing B7-H1 molecules to recruit CD8(+) T cells to the site of inflammation.

T cell suppression by naturally occurring HLA-G-expressing regulatory CD4+ T cells is IL-10-dependent and reversible.

CD4(+) T cells constitutively expressing the immune-tolerogenic HLA-G have been described recently as a new type of nT(reg) (HLA-G(pos) T(reg)) in humans. HLA-G(pos) T(reg) accumulate at sites of inflammation and are potent suppressors of T cell proliferation in vitro, suggesting their role in immune regulation. We here characterize the mechanism of how CD4(+) HLA-G(pos) T(reg) influence autologous HLA-G(neg) T(resp) function.

Intracerebral dendritic cells critically modulate encephalitogenic versus regulatory immune responses in the CNS.

Dendritic cells (DCs) appear in higher numbers within the CNS as a consequence of inflammation associated with autoimmune disorders, such as multiple sclerosis, but the contribution of these cells to the outcome of disease is not yet clear. Here, we show that stimulatory or tolerogenic functional states of intracerebral DCs regulate the systemic activation of neuroantigen-specific T cells, the recruitment of these cells into the CNS and the onset and progression of experimental autoimmune encephalomyelitis (EAE). Intracerebral microinjection of stimulatory DCs exacerbated the onset and clinical course of EAE, accompanied with an early T-cell infiltration and a decreased proportion of regulatory FoxP3-expressing cells in the brain.

Mycobacterium bovis bacille Calmette-Guérin infection in the CNS suppresses experimental autoimmune encephalomyelitis and Th17 responses in an IFN-gamma-independent manner.

Multiple sclerosis and an animal model resembling multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), are inflammatory demyelinating diseases of the CNS that are suppressed by systemic mycobacterial infection in mice and BCG vaccination in humans. Host defense responses against Mycobacterium in mice are influenced by T lymphocytes and their cytokine products, particularly IFN-gamma, which plays a protective regulatory role in EAE. To analyze the counter-regulatory role of mycobacterial infection-induced IFN-gamma in the CNS on the function of the pathological Th17 cells and the clinical outcome of EAE, we induced EAE in mice that were intracerebrally infected with Mycobacterium bovis bacille Calmette-Guerin (BCG).

A beta-lactam antibiotic dampens excitotoxic inflammatory CNS damage in a mouse model of multiple sclerosis.

In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), impairment of glial "Excitatory Amino Acid Transporters" (EAATs) together with an excess glutamate-release by invading immune cells causes excitotoxic damage of the central nervous system (CNS). In order to identify pathways to dampen excitotoxic inflammatory CNS damage, we assessed the effects of a beta-lactam antibiotic, ceftriaxone, reported to enhance expression of glial EAAT2, in "Myelin Oligodendrocyte Glycoprotein" (MOG)-induced EAE. Ceftriaxone profoundly ameliorated the clinical course of murine MOG-induced EAE both under preventive and therapeutic regimens.

Semaphorin 6D regulates the late phase of CD4+ T cell primary immune responses.

The semaphorin and plexin family of ligand and receptor proteins provides important axon guidance cues required for development. Recent studies have expanded the role of semaphorins and plexins in the regulation of cardiac, circulatory and immune system function. Within the immune system, semaphorins and plexins regulate cell-cell interactions through a complex network of receptor and ligand pairs.

The role of CD8 suppressors versus destructors in autoimmune central nervous system inflammation.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) of putative autoimmune origin. Recent evidence indicates that MS autoimmunity is linked to defects in regulatory T-cell function, which normally regulates immune responses to self-antigens and prevents autoimmune diseases. MS and its animal model, experimental autoimmune encephalomyelitis (EAE), have long been regarded as a CD4(+) T-cell-mediated autoimmune disease.

The role of regulatory T cells in multiple sclerosis.

The dysregulation of inflammatory responses and of immune self-tolerance is considered to be a key element in the autoreactive immune response in multiple sclerosis (MS). Regulatory T (T(REG)) cells have emerged as crucial players in the pathogenetic scenario of CNS autoimmune inflammation. Targeted deletion of T(REG) cells causes spontaneous autoimmune disease in mice, whereas augmentation of T(REG)-cell function can prevent the development of or alleviate variants of experimental autoimmune encephalomyelitis, the animal model of MS.

B7-H1 restricts neuroantigen-specific T cell responses and confines inflammatory CNS damage: implications for the lesion pathogenesis of multiple sclerosis.

The co-inhibitory B7-homologue 1 (B7-H1/PD-L1) influences adaptive immune responses and has been proposed to contribute to the mechanisms maintaining peripheral tolerance and limiting inflammatory damage in parenchymal organs. To understand the B7-H1/PD1 pathway in CNS inflammation, we analyzed adaptive immune responses in myelin oligodendrocyte glycoprotein (MOG)(35-55)-induced EAE and assessed the expression of B7-H1 in human CNS tissue. B7-H1(-/-) mice exhibited an accelerated disease onset and significantly exacerbated EAE severity, although absence of B7-H1 had no influence on MOG antibody production.

Pericyte-endothelial cell interaction increases MMP-9 secretion at the blood-brain barrier in vitro.

The extracellular matrix (ECM) connecting brain capillary endothelial cells (BCEC) with the surrounding brain resident cells is an essential part of the blood-brain barrier (BBB). Represented by the basement membrane which joins BCEC with brain neuroglia (astrocytes and pericytes) it forms a neurovascular unit. Neuroglia-secreted matrix metalloproteinases (MMPs) control the ECM composition and are involved in the integrity and function of the BBB during cell diapedesis and BBB breakdown after ischemia and other CNS diseases.

Short-term sPECAM-Fc treatment ameliorates EAE while chronic use hastens onset of symptoms.

The homophilic cell adhesion molecule PECAM-1 is a major participant in the migration of leukocytes across endothelium. We examined the ability of a chimeric soluble PECAM-1 fused to human IgG-Fc to impair leukocyte entry through the blood-brain barrier and reduce CNS autoimmunity. sPECAM-Fc impaired migration of lymphocytes across brain endothelial monolayers and diminished the severity of EAE, an experimental model of MS, when administered at the onset of symptoms.

The impact of glia-derived extracellular matrices on the barrier function of cerebral endothelial cells: an in vitro study.

The blood-brain barrier (BBB) is composed of the cerebral microvascular endothelium, which, together with astrocytes, pericytes, and the extracellular matrix (ECM), contributes to a "neurovascular unit". It was our objective to clarify the impact of endogenous extracellular matrices on the barrier function of BBB microvascular endothelial cells cultured in vitro. The study was performed in two consecutive steps: (i) The ECM-donating cells (astrocytes, pericytes, endothelial cells) were grown to confluence and then removed from the growth substrate by a protocol that leaves the ECM behind.

Dendritic cell transmigration through brain microvessel endothelium is regulated by MIP-1alpha chemokine and matrix metalloproteinases.

Dendritic cells (DCs) accumulate in the CNS during inflammatory diseases, but the exact mechanism regulating their traffic into the CNS remains to be defined. We now report that MIP-1alpha increases the transmigration of bone marrow-derived, GFP-labeled DCs across brain microvessel endothelial cell monolayers. Furthermore, occludin, an important element of endothelial tight junctions, is reorganized when DCs migrate across brain capillary endothelial cell monolayers without causing significant changes in the barrier integrity as measured by transendothelial electrical resistance.

Murine brain capillary endothelial cells exhibit improved barrier properties under the influence of hydrocortisone.

Hydrocortisone is known to induce barrier properties in porcine primary cultures of microvascular endothelial cells. Here we present similar effects of hydrocortisone on a serum-free in vitro model based on primary cultured mouse brain endothelial cells. These cells in culture express typical blood-brain barrier properties and the transendothelial electrical resistance is enhanced after the addition of hydrocortisone to the medium in physiological concentrations.