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Multiple sclerosis (MS) is an immune-mediated disease that targets the myelin sheath of central nervous system (CNS) neurons leading to axon injury, neuronal death, and neurological progression. Though women are more highly susceptible to developing MS, men that develop this disease exhibit greater cognitive impairment and accumulate disability more rapidly than women. Magnetic resonance imaging and pathology studies have revealed that the greater neurological progression seen in males correlates with chronic immune activation and increased iron accumulation at the rims of chronic white matter lesions as well as more intensive whole brain and grey matter atrophy and axon loss. Studies in humans and in animal models of MS suggest that male aged microglia do not have a higher propensity for inflammation, but may become more re-active at the rim of white matter lesions as a result of the presence of pro-inflammatory T cells, greater astrocyte activation or iron release from oligodendrocytes in the males. There is also evidence that remyelination is more efficient in aged female than aged male rodents and that male neurons are more susceptible to oxidative and nitrosative stress. Both sex chromosome complement and sex hormones contribute to these sex differences in biology. [ABSTRACT FROM AUTHOR]

Peroxisome proliferator-activated receptor (PPAR)-δ is a nuclear receptor that functions to maintain metabolic homeostasis, regulate cell growth, and limit the development of excessive inflammation during immune responses. Previously, we reported that PPAR-δ-deficient mice develop a more severe clinical course of experimental autoimmune encephalomyelitis (EAE); however, it was difficult to delineate the role that microglia played in this disease phenotype since PPAR-δ-deficient mice exhibited a number of immune defects that enhanced CNS inflammation upstream of microglia activation. Here, we specifically investigated the role of PPAR-δ in microglia during EAE by using mice where excision of a floxed Ppard allele was driven by expression of a tamoxifen (TAM)-inducible CX3C chemokine receptor 1 promoter-Cre recombinase transgene (Cx3cr1 CreERT2: Ppard fl/fl). We observed that by 30 days of TAM treatment, Cx3cr1 CreERT2: Ppard fl/fl mice exhibited Cre-mediated deletion primarily in microglia and this was accompanied by efficient knockdown of Ppard expression in these cells. Upon induction of EAE, TAM-treated Cx3cr1 CreERT2: Ppard fl/fl mice presented with an exacerbated course of disease compared to TAM-treated Ppard fl/fl controls. Histopathological and magnetic resonance (MR) studies on the spinal cord and brains of EAE mice revealed increased Iba-1 immunoreactivity, axonal injury and CNS tissue loss in the TAM-treated Cx3cr1 CreERT2: Ppard fl/fl group compared to controls. In early EAE, a time when clinical scores and the infiltration of CD45+ leukocytes was equivalent between Cx3cr1 CreERT2: Ppard fl/fl and Ppard fl/fl mice, Ppard -deficient microglia exhibited a more reactive phenotype as evidenced by a shorter maximum process length and lower expression of genes associated with a homeostatic microglia gene signature. In addition, Ppard -deficient microglia exhibited increased expression of genes associated with reactive oxygen species generation, phagocytosis and lipid clearance, M2-activation, and promotion of inflammation. Our results therefore suggest that PPAR-δ has an important role in microglia in limiting bystander tissue damage during neuroinflammation. [ABSTRACT FROM AUTHOR]

Experimental autoimmune encephalomyelitis (EAE) is the most common model of multiple sclerosis (MS). This model has been instrumental in understanding the events that lead to the initiation of central nervous system (CNS) autoimmunity. Though EAE has been an effective screening tool for identifying novel therapies for relapsing-remitting MS, it has proven to be less successful in identifying therapies for progressive forms of this disease. Though axon injury occurs in EAE, it is rapid and acute, making it difficult to intervene for the purpose of evaluating neuroprotective therapies. Here, we describe a variant of spontaneous EAE in the 2D2 T cell receptor transgenic mouse (2D2+ mouse) that presents with hindlimb clasping upon tail suspension and is associated with T cellmediated inflammation in the posterior spinal cord and spinal nerve roots. Due to the mild nature of clinical signs in this model, we were able to maintain cohorts of mice into middle age. Over 9 mo, these mice exhibited a relapsing-remitting course of hind-limb clasping with the development of progressive motor deficits. Using a combined approach of ex vivo magnetic resonance (MR) imaging and histopathological analysis, we observed neurological progression to associate with spinal cord atrophy, synapse degradation, and neuron loss in the gray matter, as well as ongoing axon injury in the white matter of the spinal cord. These findings suggest that mild EAE coupled with natural aging may be a solution to better modeling the neurodegenerative processes seen in MS. [ABSTRACT FROM AUTHOR]

Autoantibodies directed against endogenous proteins including contractile proteins and endothelial antigens are frequently detected in patients with heart failure and after heart transplantation. There is evidence that these autoantibodies contribute to cardiac dysfunction and correlate with clinical outcomes. Currently, autoantibodies are detected in patient sera using individual ELISA assays (one for each antigen). Thus, screening for many individual autoantibodies is laborious and consumes a large amount of patient sample. To better capture the broad-scale antibody reactivities that occur in heart failure and post-transplant, we developed a custom antigen microarray technique that can simultaneously measure IgM and IgG reactivities against 64 unique antigens using just five microliters of patient serum. We first demonstrated that our antigen microarray technique displayed enhanced sensitivity to detect autoantibodies compared to the traditional ELISA method. We then piloted this technique using two sets of samples that were obtained at our institution. In the first retrospective study, we profiled pre-transplant sera from 24 heart failure patients who subsequently received heart transplants. We identified 8 antibody reactivities that were higher in patients who developed cellular rejection (2 or more episodes of grade 2R rejection in first year after transplant as defined by revised criteria from the International Society for Heart and Lung Transplantation) compared with those who did have not have rejection episodes. In a second retrospective study with 31 patients, we identified 7 IgM reactivities that were higher in heart transplant recipients who developed antibody-mediated rejection (AMR) compared with control recipients, and in time course studies, these reactivities appeared prior to overt graft dysfunction. In conclusion, we demonstrated that the autoantibody microarray technique outperforms traditional ELISAs as it uses less patient sample, has increased sensitivity, and can detect autoantibodies in a multiplex fashion. Furthermore, our results suggest that this autoantibody array technology may help to identify patients at risk of rejection following heart transplantation and identify heart transplant recipients with AMR. [ABSTRACT FROM AUTHOR]

Ovarian cancer G protein-coupled receptor 1 (OGR1) is a proton-sensing molecule that can detect decreases in extracellular pH that occur during inflammation. Although OGR1 has been shown to have pro-inflammatory functions in various diseases, its role in autoimmunity has not been examined. We therefore sought to determine whether OGR1 has a role in the development of T cell autoimmunity by contrasting the development of experimental autoimmune encephalomyelitis between wild type and OGR1-knockout mice. OGR1-knockout mice showed a drastically attenuated clinical course of disease that was associated with a profound reduction in the expansion of myelin oligodendrocyte glycoprotein 35-55-reactive T helper 1 (Th1) and Th17 cells in the periphery and a reduced accumulation of Th1 and Th17 effectors in the central nervous system. We determined that these impaired T cell responses in OGR1-knockout mice associated with a reduced frequency and number of dendritic cells in draining lymph nodes during EAE and a higher production of nitric oxide by macrophages. Our studies suggest that OGR1 plays a key role in regulating T cell responses during autoimmunity. [ABSTRACT FROM AUTHOR]

The article discusses a study regarding the female puberty-enhanced risk of multiple sclerosis (MS) in children and central nervous system (CNS) autoimmunity in mice. Topics discussed include experimental autoimmune encephalomyelitis (EAE), acquired demyelinating syndromes (ADS), and the use of brain magnetic resonance imaging (MRI).

Background: Intravenous immunoglobulin (IVIg) has been used to treat a variety of autoimmune disorders including multiple sclerosis (MS); however its mechanism of action remains elusive. Recent work has shown that interleukin-11 (IL-11) mRNAs are upregulated by IVIg in MS patient T cells. Both IVIg and IL-11 have been shown to ameliorate experimental autoimmune encephalomyelitis (EAE), an animal model of MS. The objective of this study was to determine whether the protective effects of IVIg in EAE occur through an IL-11 and IL-11 receptor (IL-11R)-dependent mechanism. Methods: We measured IL-11 in the circulation of mice and IL-11 mRNA expression in various organs after IVIg treatment. We then followed with EAE studies to test the efficacy of IVIg in wild-type (WT) mice and in mice deficient for the IL-11 receptor (IL-11Rα−/−). Furthermore, we evaluated myelin-specific Th1 and Th17 responses and assessed spinal cord inflammation and demyelination in WT and IL-11Rα−/− mice, with and without IVIg treatment. We also examined the direct effects of mouse recombinant IL-11 on the production of IL-17 by lymph node mononuclear cells. Results: IVIg treatment induced a dramatic surge (>1000-fold increase) in the levels of IL-11 in the circulation and a prominent increase of IL-11 mRNA expression in the liver. Furthermore, we found that IL-11Rα−/− mice, unlike WT mice, although initially protected, were resistant to full protection by IVIg during EAE and developed disease with a similar incidence and severity as control-treated IL-11Rα−/− mice, despite initially showing protection. We observed that Th17 cytokine production by myelin-reactive T cells in the draining lymph nodes was unaffected by IVIg in IL-11Rα−/− mice, yet was downregulated in WT mice. Finally, IL-11 was shown to directly inhibit IL-17 production of lymph node cells in culture. Conclusion: These results implicate IL-11 as an important immune effector of IVIg in the prevention of Th17-mediated autoimmune inflammation during EAE. [ABSTRACT FROM AUTHOR]

Oral atorvastatin has prevented or reversed paralysis in the multiple sclerosis (MS) model experimental autoimmune encephalomyelitis (EAE), and reduced development of new MS lesions in clinical trials. Besides inhibiting development of encephalitogenic T cells, atorvastatin treatment of EAE has been associated with an induction of anti-inflammatory myelin-reactive T-helper type (Th)-2 cells. To investigate the clinical significance of atorvastatin-mediated Th2 differentiation, we first evaluated atorvastatin treatment in interleukin (IL)-4 green fluorescent protein-enhanced transcript (4-GET) reporter mice. Atorvastatin treatment failed to induce IL-4-producing Th2 cells in vivo; however, when T cells from atorvastatin-treated 4-GET mice were reactivated in vitro, T cells preferentially differentiated into Th2 cells, while antigen-specific T-cell proliferation and secretion of proinflammatory cytokines (interferon gamma, IL-17, tumor necrosis factor and IL-12) were reduced. Oral atorvastatin also prevented or reversed EAE in signal transducer and activator of transcription 6-deficient (STAT6-/-) mice, which cannot generate IL-4-producing Th2 cells. Further, atorvastatin treatment did not induce or expand Foxp3+ regulatory T cells in either wild-type or STAT6-/- mice. In vivo proliferation of T cells, as measured by incorporation of bromodeoxyuridine, was inhibited in atorvastatin-treated wild-type and STAT6-/- mice. These data imply that atorvastatin ameliorates central nervous system autoimmune disease by inhibiting the proliferation of encephalitogenic T cells, as opposed to induction of Th2 cells. This cytostatic effect may be a relevant mechanism of action when considering use of statins in MS and other inflammatory conditions. [ABSTRACT FROM AUTHOR]

Four questions were posed about multiple sclerosis (MS) at the 2011 Charcot Lecture, Oct. 22, 2011. 1. The Male/Female Disparity: Why are women developing MS so much more frequently than men? 2. Neuronal and Glial Protection: Are there guardian molecules that protect the nervous system in MS? 3. Predictive Medicine: With all the approved drugs, how can we rationally decide which one to use? 4. The Precise Scalpel vs. the Big Hammer for Therapy: Is antigen-specific therapy for demyelinating disease possible? To emphasize how our views on the pathogenesis and treatment of MS are evolving, and given the location of the talk in Amsterdam, Piet Mondrian’s progressive interpretations of trees serve as a heuristic. [ABSTRACT FROM AUTHOR]

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 naive 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 IFNy 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)a and PPARy. Androgens increased PPARa and decreased PPARy expression by human CD4+ T cells. PPARa siRNA-mediated knockdown had the effect of increasing IFNy by male CD4+ T cells, while transfection of CD4+ T cells with PPARy 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 IFNy and IL-17A that may be driven by expressions of PPARa and PPARy. [ABSTRACT FROM AUTHOR]

Macrophages rapidly engulf apoptotic cells to limit the release of noxious cellular contents and to restrict autoimmune responses against self antigens. Although factors participating in recognition and engulfment of apoptotic cells have been identified, the transcriptional basis for the sensing and the silent disposal of apoptotic cells is unknown. Here we show that peroxisome proliferator–activated receptor-δ (PPAR-δ) is induced when macrophages engulf apoptotic cells and functions as a transcriptional sensor of dying cells. Genetic deletion of PPAR-δ decreases expression of opsonins such as complement component-1qb (C1qb), resulting in impairment of apoptotic cell clearance and reduction in anti-inflammatory cytokine production. This increases autoantibody production and predisposes global and macrophage-specific Ppard−/− mice to autoimmune kidney disease, a phenotype resembling the human disease systemic lupus erythematosus. Thus, PPAR-δ has a pivotal role in orchestrating the timely disposal of apoptotic cells by macrophages, ensuring that tolerance to self is maintained. [ABSTRACT FROM AUTHOR]

Treatment with glatiramer acetate (GA, copolymer-1, Copaxone), a drug approved for multiple sclerosis (MS), in a mouse model promoted development of anti-inflammatory type II monocytes, characterized by increased secretion of interleukin (IL)-10 and transforming growth factor (TGF)-β, and decreased production of IL-12 and tumor necrosis factor (TNF). This anti-inflammatory cytokine shift was associated with reduced STAT-1 signaling. Type II monocytes directed differentiation of TH2 cells and CD4+CD25+FoxP3+ regulatory T cells (Treg) independent of antigen specificity. Type II monocyte–induced regulatory T cells specific for a foreign antigen ameliorated experimental autoimmune encephalomyelitis (EAE), indicating that neither GA specificity nor recognition of self-antigen was required for their therapeutic effect. Adoptive transfer of type II monocytes reversed EAE, suppressed TH17 cell development and promoted both TH2 differentiation and expansion of Treg cells in recipient mice. This demonstration of adoptive immunotherapy by type II monocytes identifies a central role for these cells in T cell immune modulation of autoimmunity. [ABSTRACT FROM AUTHOR]

Recruitment determines the profile of fibre-type-specific genes expressed across the range of muscle fibres associated with slow, fast fatigue-resistant and fast fatiguable motor units. Downstream signalling pathways activated by neural signalling and mechanical load have been the focus of intensive research in past years. It is now known that Ca2+-dependent calcineurin–nuclear factor of activated T cells and insulin-like growth factor 1 pathways and their downstream mediators contribute to these adaptive responses. These pathways regulate gene expression through muscle-specific (myocyte-enhancing factor 2, myoblast determination protein) and non-specific (nuclear factor of activated T cell 2, GATA-2) transcription factors. Transcriptional signals activated with increased contractile activity result in altered expression of fibre-type specific genes, including the myosin heavy chain isoforms and oxidative and glycolytic enzymes and a net change in muscle fibre-type composition. In contrast, transcriptional signals activated by increased load bearing result in hypertrophy or a growth response, a component of which involves satellite cell recruitment and fusion with existing adult myofibres. Calcineurin has been identified as a key mediator in the hypertrophic response, and the current challenge has been to determine the downstream target genes of this pathway. Exciting new data have emerged, showing that myostatin, a negative regulator of muscle growth, and utrophin, a cytoskeletal protein important in maintaining membrane integrity, are downstream targets of calcineurin signalling. Increased understanding of these mediators of muscle growth may provide strategies for the development of effective therapeutics to counter muscle weakness and muscular dystrophy. [ABSTRACT FROM PUBLISHER]

Studies the coordinated regulation of myosin heavy chains (MHCs) and metabolic enzymes within individual overloaded adult rat plantaris fibers. Overload-induced shifts in the expression of MHCs; Indication the shifts in MHC expression appear to correspond to the altered metabolic profiles of individual cells.

We studied the regulatory effects of nerve-mediated activity on the early expression of embryonic and adult myosin heavy chains (MHC) within inactive though still innervated rat plantaris and soleus muscle fibers. To this end, we stimulated motor nerves that were quiescent following treatment with tetrodotoxin (TTX) with paradigms designed to partition the influence of neural activation frequency and assessed the selective expression and accumulation of MHCs within muscle fibers using an array of specific antibodies. We show rapid de novo expression of IIx MHC within select soleus fibers in response to high-frequency activation for more than 0.01% of daily time. High-frequency aggregates were also the most effective in preventing the TTX-induced reexpression of embryonic MHCs within specific fibers. Only configurations that included high-frequency trains for more than 0.01% of daily time or combined with 10 Hz stimulation preserved the size of select fibers, used as a measure of the net cellular content of MHC. The effectiveness of this preservation varied according to the muscle type and MHC expressed, and, in a subset of fibers, was influenced by contractile loading status. Our results demonstrate that distinct subsets of MHC-typed fibers are differentially sensitive to the neural activation cues mediating the cellular expression of these proteins. [ABSTRACT FROM AUTHOR]

Oral atorvastatin has prevented or reversed paralysis in the multiple sclerosis (MS) model experimental autoimmune encephalomyelitis (EAE), and reduced development of new MS lesions in clinical trials. Besides inhibiting development of encephalitogenic T cells, atorvastatin treatment of EAE has been associated with an induction of anti-inflammatory myelin-reactive T-helper type (Th)-2 cells. To investigate the clinical significance of atorvastatin-mediated Th2 differentiation, we first evaluated atorvastatin treatment in interleukin (IL)-4 green fluorescent protein-enhanced transcript (4-GET) reporter mice. Atorvastatin treatment failed to induce IL-4-producing Th2 cells in vivo; however, when T cells from atorvastatin-treated 4-GET mice were reactivated in vitro, T cells preferentially differentiated into Th2 cells, while antigen-specific T-cell proliferation and secretion of proinflammatory cytokines (interferon gamma, IL-17, tumor necrosis factor and IL-12) were reduced. Oral atorvastatin also prevented or reversed EAE in signal transducer and activator of transcription 6-deficient (STAT6-/-) mice, which cannot generate IL-4-producing Th2 cells. Further, atorvastatin treatment did not induce or expand Foxp3+ regulatory T cells in either wild-type or STAT6-/- mice. In vivo proliferation of T cells, as measured by incorporation of bromodeoxyuridine, was inhibited in atorvastatin-treated wild-type and STAT6-/- mice. These data imply that atorvastatin ameliorates central nervous system autoimmune disease primarily by inhibiting proliferation of proinflammatory encephalitogenic T cells, and not simply through induction of anti-inflammatory Th2 cells. This cytostatic effect may be a relevant mechanism of action when considering use of statins in MS and other inflammatory conditions. [ABSTRACT FROM AUTHOR]

Responds to comments on the authors' papers showing that the Akt pathway is necessary and sufficient for skeletal muscle hypertrophy in vitro and in vivo. Skepticism concerning the function of the calcineurin pathway in these processes; Calcineurin activity during muscle hypertrophy; Pharmacologic inhibition of the calcineurin pathway.