Role of Magnetic Resonance Imaging and Immunotherapy in Treating Multiple Sclerosis

24S-hydroxycholesterol in plasma: a marker of cholesterol turnover in neurodegenerative diseases

Brain cholesterol is mainly involved in the cell membrane structure, in signal transduction, neurotransmitter release, synaptogenesis and membrane trafficking. Impairment of brain cholesterol metabolism was described in neurodegenerative diseases, such as Multiple Sclerosis, Alzheimer and Huntington Diseases. Since the blood-brain barrier efficiently prevents cholesterol uptake from the circulation into the brain, de novo synthesis is responsible for almost all cholesterol present there. Cholesterol is converted into 24S-hydroxycholesterol (24OHC) by cholesterol 24-hydroxylase (CYP46A1) expressed in neural cells. Plasma concentration of 24OHC depends upon the balance between cerebral production and hepatic elimination and is related to the number of metabolically active neurons in the brain. Factors affecting brain cholesterol turnover and liver elimination of oxysterols, together with the metabolism of plasma lipoproteins, genetic background, nutrition and lifestyle habits were found to significantly affect its plasma levels. Either increased or decreased plasma 24OHC concentrations were described in patients with neurodegenerative diseases. A group of evidence suggests that reduced levels of 24OHC are related to the loss of metabolically active cells and the degree of brain atrophy. Inflammation, dysfunction of BBB, increased cholesterol turnover might counteract this tendency resulting in increased levels or, in some cases, in unsignificant changes. The study of plasma 24OHC is likely to offer an insight about brain cholesterol turnover with a limited diagnostic power.

Relationship between cholesterol metabolism, ApoE and brain volumes in Alzheimer’s disease

APOE genotype, aging and midlife hypercholesterolemia are well-established risk factors for late-onset Alzheimer’s disease (AD). ApoE and cholesterol are involved in the pathogenesis of AD since they influence amyloid-β accumulation and Tau pathology. APOE ε4 carriers were found to present lower levels of amyloid-β1–42, higher tau and phosphorylated tau and a higher degree of brain atrophy at any disease stage. Presence of ApoE4 shifts the onset of the disease towards a younger age and makes progression faster. Hypercholesterolemia together with other major cardiovascular risk factors were found to be involved in the pathogenesis of AD, but reduced plasma cholesterol levels were described in demented patients. Significant correlations were found between cholesterol precursors lathosterol, lanosterol and 24S-hydroxycholesterol (a putative marker of brain cholesterol turnover) in plasma and brain atrophy as quantified by MRI. It is likely that neurodegeneration affects both brain and whole-body cholesterol metabolism in AD.

Regulatory effects of IFN-beta on production of osteopontin and IL-17 by CD4+ T Cells in MS

IFN-beta currently serves as one of the major treatments for MS. Its anti-inflammatory mechanism has been reported as involving a shift in cytokine balance from Th1 to Th2 in the T-cell response against elements of the myelin sheath. In addition to the Th1 and Th2 groups, two other important pro-inflammatory cytokines, IL-17 and osteopontin (OPN), are believed to play important roles in CNS inflammation in the pathogenesis of MS. In this study, we examined the potential effects of IFN-beta on the regulation of OPN and IL-17 in MS patients. We found that IFN-beta used in vitro at 0.5-3 ng/mL significantly inhibited the production of OPN in primary T cells derived from PBMC. The inhibition of OPN was determined to occur at the CD4(+) T-cell level. In addition, IFN-beta inhibited the production of IL-17 and IL-21 in CD4(+) T cells. It has been described that IFN-beta suppresses IL-17 production through the inhibition of a monocytic cytokine, the intracellular translational isoform of OPN. Our further investigation demonstrated that IFN-beta also acted directly on the CD4(+) T cells to regulate OPN and IL-17 expression through the type I IFN receptor-mediated activation of STAT1 and suppression of STAT3 activity. Administration of IFN-beta to EAE mice ameliorated the disease severity. Furthermore, spinal cord infiltration of OPN(+) and IL-17(+) cells decreased in IFN-beta-treated EAE mice along with decreases in serum levels of OPN and IL-21. Importantly, decreased OPN production by IFN-beta treatment contributes to the reduced migratory activity of T cells. Taken together, the results from both in vitro and in vivo experiments indicate that IFN-beta treatment can down-regulate the OPN and IL-17 production in MS. This study provides new insights into the mechanism of action of IFN-beta in the treatment of MS.

Critical regulation of CD4+ T cell survival and autoimmunity by beta-arrestin 1

CD4+ T cells are important in adaptive immunity, but their dysregulation can cause autoimmunity. Here we demonstrate that the multifunctional adaptor protein beta-arrestin 1 positively regulated naive and activated CD4+ T cell survival. We found enhanced expression of the proto-oncogene Bcl2 through beta-arrestin 1-dependent regulation of acetylation of histone H4 at the Bcl2 promoter. Mice deficient in the gene encoding beta-arrestin 1 (Arrb1) were much more resistant to experimental autoimmune encephalomyelitis, whereas overexpression of Arrb1 increased susceptibility to this disease. CD4+ T cells from patients with multiple sclerosis had much higher Arrb1 expression, and 'knockdown' of Arrb1 by RNA-mediated interference in those cells increased apoptosis induced by cytokine withdrawal. Our data demonstrate that beta-arrestin 1 is critical for CD4+ T cell survival and is a factor in susceptibility to autoimmunity.

The drug development crisis: efficiency and safety

Despite advancements in genetics, chemistry, and protein engineering, recent years have seen fewer approvals of new drugs, increases in development costs, and high-profile drug withdrawals. This article focuses on technologic methods for improving drug development efficiency. These technologies include high-content cell screening, expression profiling, mass spectroscopy, mouse models of disease, and a post-launch screening program that enables investigations of adverse drug effects. Implementation of these new technologies promises to improve performance in drug development and safety.

Induction of CD4+CD25+ regulatory T cells by copolymer-I through activation of transcription factor Foxp3

Copolymer-I (COP-I) has unique immune regulatory properties and is a treatment option for multiple sclerosis (MS). This study revealed that COP-I induced the conversion of peripheral CD4+CD25- to CD4+CD25+ regulatory T cells through the activation of transcription factor Foxp3. COP-I treatment led to a significant increase in Foxp3 expression in CD4+ T cells in MS patients whose Foxp3 expression was reduced at baseline. CD4+CD25+ T cell lines generated by COP-I expressed high levels of Foxp3 that correlated with an increased regulatory potential. Furthermore, we demonstrated that the induction of Foxp3 in CD4+ T cells by COP-I was mediated through its ability to produce IFN-gamma and, to a lesser degree, TGF-beta1, as shown by antibody blocking and direct cytokine induction of Foxp3 expression in T cells. It was evident that in vitro treatment and administration with COP-I significantly raised the level of Foxp3 expression in CD4+ T cells and promoted conversion of CD4+CD25+ regulatory T cells in wild-type B6 mice but not in IFN-gamma knockout mice. This study provides evidence for the role and mechanism of action of COP-I in the induction of CD4+CD25+ regulatory T cells in general and its relevance to the treatment of MS.