Increased frequency of canine distemper virus-specific antibodies in multiple sclerosis.

BACKGROUND AND PURPOSE: Canine distemper virus (CDV) is a candidate agent in the etiology of multiple sclerosis (MS). Elevated anti-CDV levels were previously found in the sera from MS patients compared with controls. We now investigated whether there was an age-related association with the presence of antibodies specific to CDV-hemagglutinin (H) protein in MS. METHODS: Sera from patients with MS, other neurological diseases, and inflammatory and/or autoimmune diseases, and healthy individuals were screened for anti-CDV in an ELISA using linear peptides of the CDV-H protein as antigen. Antibody levels to measles and varicella-zoster virus were measured and served as controls. RESULTS: Analysis of the new cohort of MS patients and controls confirmed our initial finding of elevated anti-CDV-H levels in MS patients. An increase in measles but not varicella-zoster virus antibody levels was found in MS patients compared with healthy controls. Data from the new cohort of patients and controls were combined with data from the original study and analyzed with respect to age distribution of anti-CDV IgG. Mean CDV antibody levels were significantly elevated in each decade from 20 to 50 years of age in MS compared with healthy and disease controls. Antibody levels to measles virus were not consistently elevated during this age span. A striking relationship (p < .0001, odds ratio = 5.0) was observed between elevated anti-CDV-H levels and diagnosis of MS. CONCLUSIONS: The finding that anti-CDV levels are elevated in MS patients of all ages provides substantial evidence of a strong association between elevated anti-CDV and MS.

Human CD39+ Treg Cells Express Th17-Associated Surface Markers and Suppress IL-17 via a Stat3-Dependent Mechanism.

Human CD4+ T regulatory cells (Tregs) are a population of phenotypically and functionally diverse cells that downregulate inflammatory and autoimmune responses. As Th17 cells play an important role in the pathogenesis of autoimmune diseases, it is critical to elucidate the mechanisms regulating these cells. In this study, we examined the molecular basis underlying the phenotypic and functional diversity of human Tregs expressing the ectonucleotidase CD39. CD4+CD25hiCD39+ Tregs inhibit the proliferative response and the secretion of IL-17 and IFN-γ of autologous CD4+ T effector cells, while CD4+CD25hiCD39- Tregs only suppress IFN-γ production. We demonstrate that activated human CD4+CD25hiCD39+ Tregs express the Th17-associated surface markers CCR6 and IL-23R, and phosphorylate the transcription factor Stat3. Moreover, suppression of IL-17 by CD4+CD25hiCD39+ Tregs occurs via a Stat3-dependent mechanism as inhibition of Stat3 activation in the CD39+ Tregs reverses their ability to suppress IL-17. CD4+CD25hiCD39- Tregs are not endowed with the ability to inhibit IL-17 as they do not upregulate CCR6 or the IL-23R, and furthermore, they secrete IL-17. Our findings provide the first evidence that human Treg functional diversity is matched to the type of immune response being regulated and reveal a new role for Stat3 in controlling Treg function.

Lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNFα) blunt the response of Neuropeptide Y/Agouti-related peptide (NPY/AgRP) glucose inhibited (GI) neurons to decreased glucose.

A population of Neuropeptide Y (NPY) neurons which co-express Agouti-related peptide (AgRP) in the arcuate nucleus of the hypothalamus (ARC) are inhibited at physiological levels of brain glucose and activated when glucose levels decline (e.g. glucose-inhibited or GI neurons). Fasting enhances the activation of NPY/AgRP-GI neurons by low glucose. In the present study we tested the hypothesis that lipopolysaccharide (LPS) inhibits the enhanced activation of NPY/AgRP-GI neurons by low glucose following a fast. Mice which express green fluorescent protein (GFP) on their NPY promoter were used to identify NPY/AgRP neurons. Fasting for 24h and LPS injection decreased blood glucose levels. As we have found previously, fasting increased c-fos expression in NPY/AgRP neurons and increased the activation of NPY/AgRP-GI neurons by decreased glucose. As we predicted, LPS blunted these effects of fasting at the 24h time point. Moreover, the inflammatory cytokine tumor necrosis factor alpha (TNFα) blocked the activation of NPY/AgRP-GI neurons by decreased glucose. These data suggest that LPS and TNFα may alter glucose and energy homeostasis, in part, due to changes in the glucose sensitivity of NPY/AgRP neurons. Interestingly, our findings also suggest that NPY/AgRP-GI neurons use a distinct mechanism to sense changes in extracellular glucose as compared to our previous studies of GI neurons in the adjacent ventromedial hypothalamic nucleus.

Case report: cytokine and CD4+ T-cell profiles of monozygotic twins with autism and divergent comorbidities and drug treatment.

Autism spectrum disorders are neurodevelopmental disorders that are thought to be caused by a gene-by-environment interaction and in which various immune alterations are reported. We investigate CD4(+) T-cell cytokine profiles and subpopulations in 19-year-old monozygotic twins with autism and different comorbidities. CD4(+) T cells from the twin with epilepsy produce more interferon-gamma, less interleukin-17, and have an increased interferon-γ/interleukin-4 ratio. CD4(+) T cells from the twin with multiple sclerosis exhibit a cytokine profile similar to an age and gender-matched control and a higher percentage of T regulatory (Treg) cells. The twins' mother's T cells produce very high levels of both interleukin-17 and interferon-γ. Cytokine and CD4(+) T-cell abnormalities in the twins could contribute to or be a result of the manifestation of their divergent comorbidities. A proinflammatory, autoimmune-polarized cytokine profile is observed in this unique family with autism.

1,25-dihydroxyvitamin D(3) ameliorates Th17 autoimmunity via transcriptional modulation of interleukin-17A.

A new class of inflammatory CD4(+) T cells that produce interleukin-17 (IL-17) (termed Th17) has been identified, which plays a critical role in numerous inflammatory conditions and autoimmune diseases. The active form of vitamin D, 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], has a direct repressive effect on the expression of IL-17A in both human and mouse T cells. In vivo treatment of mice with ongoing experimental autoimmune encephalomyelitis (EAE; a mouse model of multiple sclerosis) diminishes paralysis and progression of the disease and reduces IL-17A-secreting CD4(+) T cells in the periphery and central nervous system (CNS). The mechanism of 1,25(OH)(2)D(3) repression of IL-17A expression was found to be transcriptional repression, mediated by the vitamin D receptor (VDR). Transcription assays, gel shifting, and chromatin immunoprecipitation (ChIP) assays indicate that the negative effect of 1,25(OH)(2)D(3) on IL-17A involves blocking of nuclear factor for activated T cells (NFAT), recruitment of histone deacetylase (HDAC), sequestration of Runt-related transcription factor 1 (Runx1) by 1,25(OH)(2)D(3)/VDR, and a direct effect of 1,25(OH)(2)D(3) on induction of Foxp3. Our results describe novel mechanisms and new concepts with regard to vitamin D and the immune system and suggest therapeutic targets for the control of autoimmune diseases.

Interleukin-27-mediated suppression of human Th17 cells is associated with activation of STAT1 and suppressor of cytokine signaling protein 1.

Accumulating evidence indicates that interleukin (IL)-27, a member of the IL-12 family of cytokines, antagonizes pathological Th17 effector cell responses. Relatively little is known about the cytokines that regulate human Th17 cells. In this study, we investigated the effect of IL-27 on the differentiation of human Th17 cells and on committed memory Th17 cells. We demonstrate that IL-27 suppresses the development of human Th17 cells by downregulating retinoid orphan nuclear receptor C expression and that this inhibition is associated with the induction of the intracellular signaling factors STAT1 and induction of the suppressor of cytokine signaling protein 1. The IL-27-mediated inhibition of IL-17 is independent of IL-10. We show that IL-27 inhibits differentiation of naïve T cells into IL-17(+) T cells under different Th17 polarizing conditions. IL-27 suppresses other Th17 subset cytokines such as IL-22 and IL-21 but not tumor necrosis factor-α. Moreover, we also show that IL-27 inhibits IL-17 production by committed Th17 memory cells, which is independent of IL-10. These studies show that IL-27 negatively regulates both the developing and committed human Th17 responses and therefore may be a promising therapeutic approach in the treatment of Th17-mediated diseases.

Cross-linking of GM1 ganglioside by galectin-1 mediates regulatory T cell activity involving TRPC5 channel activation: possible role in suppressing experimental autoimmune encephalomyelitis.

Several animal autoimmune disorders are suppressed by treatment with the GM1 cross-linking units of certain toxins such as B subunit of cholera toxin (CtxB). Due to the recent observation of GM1 being a binding partner for the endogenous lectin galectin-1 (Gal-1), which is known to ameliorate symptoms in certain animal models of autoimmune disorders, we tested the hypothesis that an operative Gal-1/GM1 interplay induces immunosuppression in a manner evidenced by both in vivo and in vitro systems. Our study of murine experimental autoimmune encephalomyelitis (EAE) indicated suppressive effects by both CtxB and Gal-1 and further highlighted the role of GM1 in demonstrating enhanced susceptibility to EAE in mice lacking this ganglioside. At the in vitro level, polyclonal activation of murine regulatory T (Treg) cells caused up-regulation of Gal-1 that was both cell bound and released to the medium. Similar activation of murine CD4(+) and CD8(+) effector T (Teff) cells resulted in significant elevation of GM1 and GD1a, the neuraminidase-reactive precursor to GM1. Activation of Teff cells also up-regulated TRPC5 channels which mediated Ca(2+) influx upon GM1 cross-linking by Gal-1 or CtxB. This involved co-cross-linking of heterodimeric integrin due to close association of these alpha(4)beta(1) and alpha(5)beta(1) glycoproteins with GM1. Short hairpin RNA (shRNA) knockdown of TRPC5 in Teff cells blocked contact-dependent proliferation inhibition by Treg cells as well as Gal-1/CtxB-triggered Ca(2+) influx. Our results thus indicate GM1 in Teff cells to be the primary target of Gal-1 expressed by Treg cells, the resulting co-cross-linking and TRPC5 channel activation contributing importantly to the mechanism of autoimmune suppression.

Regulation of IL-17 in human CCR6+ effector memory T cells.

IL-17-secreting T cells represent a distinct CD4(+) effector T cell lineage (Th17) that appears to be essential in the pathogenesis of numerous inflammatory and autoimmune diseases. Although extensively studied in the murine system, human Th17 cells have not been well characterized. In this study, we identify CD4(+)CD45RO(+)CCR7(-)CCR6(+) effector memory T cells as the principal IL-17-secreting T cells. Human Th17 cells have a unique cytokine profile because the majority coexpress TNF-alpha but not IL-6 and a minor subset express IL-17 with IL-22 or IL-17 and IFN-gamma. We demonstrate that the cytokines that promote the differentiation of human naive T cells into IL-17-secreting cells regulate IL-17 production by memory T cells. IL-1beta alone or in association with IL-23 and IL-6 markedly increase IL-17(+) CCR6(+) memory T cells and induce IL-17 production in CCR6(-) memory T cells. We also show that T cell activation induces Foxp3 expression in T cells and that the balance between the percentage of Foxp3(+) and IL-17(+) T cells is inversely influenced by the cytokine environment. These studies suggest that the cytokine environment may play a critical role in the expansion of memory T cells in chronic autoimmune diseases.

Presence of sodium-calcium exchanger/GM1 complex in the nuclear envelope of non-neural cells: nature of exchanger-GM1 interaction.

Previous studies have revealed the presence of Na+ / Ca2+ exchanger (NCX) activity associated with GM1 ganglioside in the nuclear envelope (NE) of neurons and glia as well as various neural cell lines. The nuclear NCX1 exchanger, unlike that in the plasma membrane, was shown to be tightly associated with GM1 and potentiated by the latter. One non-neural cell line, Jurkat, was found to contain no Na+ / Ca2+ exchanger of the NCX1, NCX2, or NCX3 types in either nuclear or plasma membrane. To determine whether such absence in the NE is generally characteristic of non-neural cells we have examined two more such cell lines in addition to human lymphocytes. RT-PCR showed NCX1 expression in both HeLa and NCTC cell lines and also NCX2 in the latter; NCX3, a subtype previously observed in NG108-15 cells, was not expressed in either. Immunocytochemical and immunoblot studies indicated NCX1 on the cell surface and nuclear envelope of both cell types. Some alternatively spliced isoforms of NCX1 in the nuclear envelope of both cell types were tightly associated with ganglioside GM1. Human lymphocytes, a mixed population of T and B cells, showed similar evidence for plasma membrane and nuclear expression in some but not all cells. The high affinity association between NCX1 and GM1, explored by reaction with base, acid, and proteases, was found to involve charge-charge interaction with a requirement for a positively charged moiety in NCX.

Linkage analysis conditional on HLA status in a large North American pedigree supports the presence of a multiple sclerosis susceptibility locus on chromosome 12p12.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system with a probable immune-mediated pathogenesis. Strong evidence supports the hypothesis that MS is determined by genetic and environmental factors, but these factors remain largely undefined. The genetic component is suggested by a higher concordance rate in monozygotic (28%) versus dizygotic (5%) twins as well as familial recurrence risk. Several studies have shown association of MS with the histocompatibility leukocyte antigen (HLA) class II region, specifically DR15, DQ6. However, there is no convincing evidence of a common susceptibility locus. We have identified a pedigree of Pennsylvania Dutch extraction, in which MS segregates with an autosomal dominant inheritance pattern. We have collected blood samples from 18 family members, seven of whom show typical signs of MS lesions by magnetic resonance imaging. The 18 individuals were serotyped for HLA class I and II and analyzed by a genome-wide screen for linkage analysis. We have found evidence for suggestive linkage to markers on 12p12 with a maximum multipoint LOD score of 2.71, conditional on the presence of DR15, DQ6. Contingency table analysis showed that all MS affected individuals have both the DR15, DQ6 allele and the 12p12 haplotype whereas the unaffected individuals have either one or neither of these markers (P = 0.00011). Our data suggests that both HLA DR15, DQ6 and a novel locus on chromosome 12p12 may be necessary for development of MS in this family.