April 23, 2018April 10, 2018Free AccessDietary Conjugated Linoleic Acid Supplementation Modulates CNS Autoimmunity (P2.413)Ann-Katrin Fleck, Stephanie Hucke, Marvin Hartwig, Flavio Teipel, Martin Herold, Kerstin Berer, Marie Liebmann, … Show All … , Ivan Kuzmanov, Berit Grützke, Angelos Sagredos, Maria Eveslage, Catharina C. Gross, Gurumoorthy Krishnamoorthy, Ulrich Dobrindt, Tanja Kuhlmann, Heinz Wiendl, and Luisa Klotz Show FewerAuthors Info & AffiliationsApril 10, 2018 issue90 (15_supplement)https://doi.org/10.1212/WNL.90.15_supplement.P2.413 Letters to the Editor

The autoimmune neurological disease, Multiple Sclerosis (MS), have increased at alarming rates in the Western society over the last few decades. While there are numerous efforts to develop novel treatment approaches, there is an unmet need to identify preventive strategies. We explored whether central nervous system (CNS) autoimmunity can be prevented through dietary manipulation using a spontaneous autoimmune encephalomyelitis mouse model. We report that the nutritional supplementation of non-fermentable fiber, common components of a vegetarian diet, in early adult life, prevents autoimmune disease. Dietary non-fermentable fiber alters the composition of the gut microbiota and metabolic profile with an increase in the abundance of long-chain fatty acids. Immune assays revealed that cecal extracts and a long chain fatty acid but not cecal lysates promoted autoimmune suppressive TH2 immune responses, demonstrating that non-fermentable fiber-induced metabolic changes account for the beneficial effects. Overall, these findings identify a non-invasive dietary strategy to prevent CNS autoimmunity and warrants a focus on nutritional approaches in human MS.

There is emerging evidence that the commensal microbiota has a role in the pathogenesis of multiple sclerosis (MS), a putative autoimmune disease of the CNS. Here, we compared the gut microbial composition of 34 monozygotic twin pairs discordant for MS. While there were no major differences in the overall microbial profiles, we found a significant increase in some taxa such as Akkermansia in untreated MS twins. Furthermore, most notably, when transplanted to a transgenic mouse model of spontaneous brain autoimmunity, MS twin-derived microbiota induced a significantly higher incidence of autoimmunity than the healthy twin-derived microbiota. The microbial profiles of the colonized mice showed a high intraindividual and remarkable temporal stability with several differences, including Sutterella, an organism shown to induce a protective immunoregulatory profile in vitro. Immune cells from mouse recipients of MS-twin samples produced less IL-10 than immune cells from mice colonized with healthy-twin samples. IL-10 may have a regulatory role in spontaneous CNS autoimmunity, as neutralization of the cytokine in mice colonized with healthy-twin fecal samples increased disease incidence. These findings provide evidence that MS-derived microbiota contain factors that precipitate an MS-like autoimmune disease in a transgenic mouse model. They hence encourage the detailed search for protective and pathogenic microbial components in human MS.

Monoclonal Abs against CD20 reduce the number of relapses in multiple sclerosis (MS); commonly this effect is solely attributed to depletion of B cells. Recently, however, a subset of CD3(+)CD20(+) T cells has been described that is also targeted by the anti-CD20 mAb rituximab. Because the existence of cells coexpressing CD3 and CD20 is controversial and features of this subpopulation are poorly understood, we studied this issue in detail. In this study, we confirm that 3-5% of circulating human T cells display CD20 on their surface and transcribe both CD3 and CD20. We report that these CD3(+)CD20(+) T cells pervade thymus, bone marrow, and secondary lymphatic organs. They are found in the cerebrospinal fluid even in the absence of inflammation; in the cerebrospinal fluid of MS patients they occur at a frequency similar to B cells. Phenotypically, these T cells are enriched in CD8(+) and CD45RO(+) memory cells and in CCR7(-) cells. Functionally, they show a higher frequency of IL-4-, IL-17-, IFN-γ-, and TNF-α-producing cells compared with T cells lacking CD20. CD20-expressing T cells respond variably to immunomodulatory treatments given to MS patients: they are reduced by fingolimod, alemtuzumab, and dimethyl fumarate, whereas natalizumab disproportionally increases them in the blood. After depletion by rituximab, they show earlier and higher repopulation than CD20(+) B cells. Taken together, human CD3(+)CD20(+) T cells pervade lymphatic organs and the cerebrospinal fluid, have a strong ability to produce different cytokines, and respond to MS disease modifying drugs.

Environmental factors are suspected to trigger Multiple sclerosis (MS) in people with genetic disease susceptibility. Although little is known about the nature of the environmental trigger(s), emerging evidence from animal models of MS suggests that the gut flora is critically required for disease development. Antibiotics can rapidly alter gut microbial signatures. Thus, we evaluated the effect of antibiotic interventions on CNS autoimmunity using a transgenic mouse model of opticospinal experimental autoimmune encephalomyelitis (EAE; OSE mouse). OSE mice harbor myelin oligodendrocyte glycoprotein (MOG)-specific T as well as B cells. Approximately 50% of untreated OSE mice develop spontaneous EAE. In contrast, 4 week-old mice treated for 2 weeks with an antibiotic cocktail remain fully protected from the disease. Analysis by 16s RNA sequencing revealed that antibiotic treatment had profound impact on the composition of the intestinal microbiota. Interestingly, changes in the intestinal microbiota were accompanied by a reduction of the Interleukin-22 serum level. Work to identify the mechanisms how antibiotic treatment and hence, alteration of the intestinal microbiota can dampen the autoaggressive immune response is underway. In summary, these findings demonstrate that alteration of gut bacteria can have a profound impact on CNS-specific autoimmunity.

BAFF and a proliferation-inducing ligand (APRIL), which control B cell homeostasis, are therapeutic targets in autoimmune diseases. TACI-Fc (atacicept), a soluble fusion protein containing the extracellular domain of the BAFF–APRIL receptor TACI, was applied in clinical trials. However, disease activity in multiple sclerosis unexpectedly increased, whereas in systemic lupus erythematosus, atacicept was beneficial. In this study, we show that an endogenous soluble TACI (sTACI) exists in vivo. TACI proteolysis involved shedding by a disintegrin and metalloproteinase 10 releasing sTACI from activated B cells. The membrane-bound stub was subsequently cleaved by γ-secretase reducing ligand-independent signaling of the remaining C-terminal fragment. The shed ectodomain assembled ligand independently in a homotypic way. It functioned as a decoy receptor inhibiting BAFF- and APRIL-mediated B cell survival and NF-κB activation. We determined sTACI levels in autoimmune diseases with established hyperactivation of the BAFF–APRIL system. sTACI levels were elevated both in the cerebrospinal fluid of the brain-restricted autoimmune disease multiple sclerosis correlating with intrathecal IgG production, as well as in the serum of the systemic autoimmune disease systemic lupus erythematosus correlating with disease activity. Together, we show that TACI is sequentially processed by a disintegrin and metalloproteinase 10 and γ-secretase. The released sTACI is an immunoregulator that shares decoy functions with atacicept. It reflects systemic and compartmentalized B cell accumulation and activation.

A recently developed mechanical method for extracting long bamboo fibres opens the possibility to exploit this new material as reinforcement in composite materials for high end uses. The strength distribution of the fibres was characterized in a novel approach to evaluate the effect of defects introduced by the extraction process as function of different scale variables: fibre length, fibre surface area and fibre volume. The modified Weibull distribution, a practical model requiring only three parameters, described accurately the fibre strength distribution of the fibres at different gauge lengths. The average fibre strength decreased with increasing gauge length, from 943 MPa at L = 1 mm to 733 MPa at L = 40 mm and it was nearly independent of the mean fibre volume. The Weibull shape parameter was found to be 7.6 for all tested fibres, showing low strength variability in comparison with other natural fibres and some synthetic fibres, indicating their high quality.

Multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS), presents as a complex disease with variable clinical and pathological manifestations, involving different pathogenic pathways. Animal models, particularly experimental autoimmune encephalomyelitis (EAE), have been key to deciphering the pathophysiology of MS, although no single model can recapitulate the complexity and diversity of MS, or can, to date, integrate the diverse pathogenic pathways. Since the first EAE model was introduced decades ago, multiple classic (induced), spontaneous, and humanized EAE models have been developed, each recapitulating particular aspects of MS pathogenesis. The advances in technologies of genetic ablation and transgenesis in mice of C57BL/6J background and the development of myelin-oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6J mice yielded several spontaneous and humanized EAE models, and resulted in a plethora of EAE models in which the role of specific genes or cell populations could be precisely interrogated, towards modeling specific pathways of MS pathogenesis/regulation in MS. Collectively, the numerous studies on the different EAE models contributed immensely to our basic understanding of cellular and molecular pathways in MS pathogenesis as well as to the development of therapeutic agents: several drugs available today as disease modifying treatments were developed from direct studies on EAE models, and many others were tested or validated in EAE. In this review, we discuss the contribution of major classic, spontaneous, and humanized EAE models to our understanding of MS pathophysiology and to insights leading to devising current and future therapies for this disease.

Not much is known about the initial events leading to the development of the central nervous system (CNS)-specific autoimmune disorder Multiple Sclerosis (MS). Environmental factors are suspected to trigger the pathogenic events in people with genetic disease susceptibility. Historically, many infectious microbes were linked to MS, but no infection has ever been demonstrated to be the cause of the disease. Recent emerging evidence from animal models of MS suggests a causal link with resident commensal bacteria. Microbial organisms may trigger the activation of CNS-specific, auto-aggressive lymphocytes either through molecular mimicry or via bystander activation. In addition, several gut microbial metabolites and bacterial products may interact with the immune system to modulate CNS autoimmunity.

Regulatory T cells are crucial in controlling various functions of effector T cells during experimental autoimmune encephalomyelitis. While regulatory T cells are reported to exert their immunomodulatory effects in the peripheral immune organs, their role within the central nervous system (CNS) during experimental autoimmune encephalomyelitis is unclear. Here, by combining a selectively timed regulatory T cells depletion with 2-photon microscopy, we report that regulatory T cells exercise their dynamic control over effector T cells in the CNS. Acute depletion of regulatory T cells exacerbated experimental autoimmune encephalomyelitis severity which was accompanied by increased pro-inflammatory cytokine production and proliferation of effector T cells. Intravital microscopy revealed that, in the absence of regulatory T cells, the velocity of effector T cells was decreased with simultaneous increase in the proportion of stationary phase cells in the CNS. Based on these data, we conclude that regulatory T cells mediate recovery from experimental autoimmune encephalomyelitis by controlling cytokine production, proliferation and motility of effector T cells in the CNS.

Myelin-specific, pro-inflammatory TH17 cells are widely regarded as the drivers of experimental autoimmune encephalomyelitis (EAE), an animal model for Multiple sclerosis (MS). The factors, responsible for the generation and maintenance of TH17 cells as well as their participation in the pathogenic cascade leading to the demyelinating disease, have been studied extensively. However, how these harmful autoreactive cells are controlled in vivo remains unclear. By comparing TCR transgenic mice on a disease susceptible and a disease resistant genetic background, we show here that pathogenic TH17 cells are sequestered within the intestine of spontaneous EAE resistant B10.S mice. Disease resistant B10.S mice harbored higher frequencies of TH17 cells in the intestine compared to EAE susceptible SJL/J mice. Moreover, transferred TH17 cells selectively migrated to intestinal lymphoid organs of B10.S mice. The sequestration of TH17 cells in the gut was partially dependent on the gut homing receptor α4β7-mediated adhesion to the intestine. Administration of α4β7 blocking-antibodies increased the peripheral availability of TH17 cells, resulting in increased EAE severity after immunization in B10.S mice. Together, these results support the concept that the intestine is a check-point for controlling pathogenic, organ-specific T cells.

Environmental factors are suspected to trigger multiple sclerosis (MS) in people with genetic disease susceptibility. Although little is known about the nature of the environmental trigger(s), emerging evidence from animal models of MS suggests that the gut flora is critically required for disease development. Besides antibiotics, dietary factors can rapidly alter gut microbial signatures. Hence, we evaluated the influence of different experimental diets on CNS autoimmunity using a mouse model of spontaneous experimental autoimmune encephalomyelitis (EAE). While control mice developed disease with a 60% incidence, animals fed with other experimental diets were protected from spontaneous EAE. Protection from the disease was accompanied by a significant reduction in IFN-gamma-producing TH1 cells. Splenic T cells secreted less IFN-gamma in response to stimulation with cognate antigen or anti-CD3 mAb. However, stimulation with anti-CD3/anti-CD28 mAb detected comparable levels of IFN-γ secretion, indicative of a defective antigen presentation. Indeed, analysis of antigen presenting cells showed lower expression levels of co-stimulatory molecules, like CD80 and CD86. Although diet changes modified the intestinal microbiota composition, the outgrowth of a specific bacterium was noted by 16s rRNA sequencing as well as culturing techniques. Work to identify the mechanisms on how the specific gut bacterium can shape the immune response is underway. In summary, these findings demonstrate that dietary metabolism by specific gut bacteria can have a profound impact on CNS-specific autoimmunity.

The BAFF-APRIL system is critically involved in controlling B-cell homeostasis. Here the receptor TACI has ambiguous functions: while humans with TACI mutations present with antibody deficiency syndroms, TACI−/− mice develop autoimmunity and lymphoproliferation. Generation of soluble receptors is a common feature in the regulation of inflammatory processes. In our study we identify soluble TACI (sTACI) and characterize the structure and function of this soluble receptor.

Background and Purpose— Recent genome-wide association studies identified the histone deacetylase 9 ( HDAC9 ) gene region as a major risk locus for large-vessel stroke and coronary artery disease. However, the mechanisms linking variants at this locus to vascular risk are poorly understood. In this study, we investigated the candidacy and directionality of HDAC9 in atherosclerosis and analyzed associations between risk alleles at 7p21.1 and plaque characteristics. Methods— Allele-dependent expression of HDAC9 was analyzed in human peripheral blood mononuclear cells of healthy donors. Effects of HDAC9 deficiency on atherosclerotic plaques were investigated in 18- and 28-week-old ApoE −/− mice by histology and immunohistochemistry. We further performed detailed plaque phenotyping and genotyping of rs2107595, the lead single-nucleotide polymorphism for large-vessel stroke, in carotid endarterectomy samples of 1858 subjects from the Athero-Express study. Results— Gene expression studies in peripheral blood mononuclear cells revealed increased mRNA levels of HDAC9 but not of neighboring genes ( TWIST1/FERD3L ) in risk allele carriers of rs2107595. Compared with HDAC9 +/+ ApoE −/− mice, HDAC9 −/− ApoE −/− mice exhibited markedly reduced lesion sizes throughout atherosclerotic aortas and significantly less advanced lesions. The proportion of Mac3-positive macrophages was higher in plaques from HDAC9 −/− ApoE −/− mice, but this was largely because of a lower proportion of advanced lesions. Analysis of human atherosclerotic plaques revealed no association between rs2107595 and specific plaque characteristics. Conclusions— Our results suggest that HDAC9 represents the disease-relevant gene at the stroke and coronary artery disease risk locus on 7p21.1, and that risk alleles in this region mediate their effects through increased HDAC9 expression. Targeted inhibition of HDAC9 might be a viable strategy to prevent atherosclerosis.

Converging evidence indicates that multiple sclerosis, an inflammatory demyelinating disease of the central nervous system, is caused by brain-specific, self-reactive T lymphocytes. These are normal components embedded in the human immune system throughout healthy life. Only upon activation in the periphery, the T cells assume properties that enable them to break through the vascular blood-brain barrier and to invade the brain white matter. While activation has been traditionally associated with microbial infections, recently, studies of animal models revealed a critical role of the commensal gut flora as a key triggering factor. These findings may pave the way to new strategies to treat MS and other human autoimmune diseases, and commend a reevaluation of dietary approaches.

Multiple sclerosis (MS) and other chronic inflammatory autoimmune diseases represent major public health challenges in industrialised Western society. MS results from an autoimmune attack against myelin structures by self-reactive lymphocytes, which are normal components of the healthy immune repertoire. The nature of the triggers that convert the innocuous self-reactive lymphocytes into an autoaggressive phenotype is poorly understood. In the past, it was primarily suspected that pathogenic infections trigger MS. However, so far, none of the incriminated pathogenic microbes were firmly associated with the disease. A growing body of evidence in animal models of MS implicates the gut microbiota in the induction of central nervous system (CNS) autoimmunity. The mammalian gut harbors a diverse population of microbial organisms which are essential for our well being. There is an increasing understanding that the gut microbiota not only modulates the local immune functions but also affects the systemic immune system. We are only just beginning to understand the nature of the interactions of the gut microbiota with the host’s immune system especially in the context of autoimmune diseases. This review will address the influence of intestinal microbiota on immune homeostasis and on the development of autoimmune responses at sites distal to the intestine with a particular emphasis placed on a discussion about CNS autoimmunity.

Role of gut bacteria in triggering multiple sclerosis There is controversy over the nature of the early stages of multiple sclerosis: some suggest that the initiation process involves primary changes in the central nervous system, others that pathogenesis originates in the immune system. Support for the latter concept comes from the finding that intact commensal microbiota are required for autoimmune disease in a spontaneous mouse model for relapsing–remitting multiple sclerosis. Microbial exposure is necessary but not sufficient for disease induction, which requires the presence of the target myelin autoantigen, MOG. The possible involvement of diet and microbiota in autoimmune disease may provide novel therapeutic approaches.

B cells and their secreted products participate in the intricate network of pathogenic and regulatory immune responses. In human autoimmune diseases like rheumatoid arthritis, systemic lupus erythematosus and type 1 diabetes, a role for B cells and antibodies is well established. However, in multiple sclerosis (MS), despite the presence of autoantibodies, B cells were less considered as a major participant of autoimmune processes, until recently. Several lines of evidence now indicate a more active role for B cells in disease pathogenesis. In this review, we discuss the diverse roles of B cells in autoimmune diseases with particular focus on multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE) as well as the recently generated spontaneous EAE mouse models.