Neither T-helper type 2 nor Foxp3 + regulatory T cells are necessary for therapeutic benefit of atorvastatin in treatment of central nervous system autoimmunity
TL;DR: 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.
Abstract: 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.
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TL;DR: Several strategies of treatment which have been shown to be effective or are proposed as potential therapies to restore the function of various Treg subsets including Tr1, iTr35, nTregs, and iTregs appear promising for treating patients with MS or MG.
Abstract: Multiple sclerosis (MS) is a chronic debilitating disease of the central nervous system primarily mediated by T lymphocytes with specificity to neuronal antigens in genetically susceptible individuals. On the other hand, myasthenia gravis (MG) primarily involves destruction of the neuromuscular junction by antibodies specific to the acetylcholine receptor. Both autoimmune diseases are thought to result from loss of self-tolerance, which allows for the development and function of autoreactive lymphocytes. Although the mechanisms underlying compromised self-tolerance in these and other autoimmune diseases have not been fully elucidated, one possibility is numerical, functional, and/or migratory deficits in T regulatory cells (Tregs). Tregs are thought to play a critical role in the maintenance of peripheral immune tolerance. It is believed that Tregs function by suppressing the effector CD4+ T cell subsets that mediate autoimmune responses. Dysregulation of suppressive and migratory markers on Tregs have been linked to the pathogenesis of both MS and MG. For example, genetic abnormalities have been found in Treg suppressive markers CTLA-4 and CD25, while others have shown a decreased expression of FoxP3 and IL-10. Furthermore, elevated levels of pro-inflammatory cytokines such as IL-6, IL-17, and IFN-γ secreted by T effectors have been noted in MS and MG patients. This review provides several strategies of treatment which have been shown to be effective or are proposed as potential therapies to restore the function of various Treg subsets including Tr1, iTr35, nTregs, and iTregs. Strategies focusing on enhancing the Treg function find importance in cytokines TGF-β, IDO, interleukins 10, 27, and 35, and ligands Jagged-1 and OX40L. Likewise, strategies which affect Treg migration involve chemokines CCL17 and CXCL11. In pre-clinical animal models of experimental autoimmune encephalomyelitis (EAE) and experimental autoimmune myasthenia gravis (EAMG), several strategies have been shown to ameliorate the disease and thus appear promising for treating patients with MS or MG.
221 citations
Cites background from "Neither T-helper type 2 nor Foxp3 +..."
...Administration of cholesterol-reducing statins such as atorvastatin inhibited the development of EAE without increasing the frequency of FoxP3 Treg cells or Th2 cells, yet there was a substantial increase in IL-10 expression [109]....
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...Treatments such as the lipid-lowering drug atorvastatin mentioned earlier have no effect on the FoxP3 Treg population, indicating that increasing the Treg population, although may be desirable, may not always be necessary [109]....
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...Many treatments which increase Tregs in EAE have been found to be efficacious, while other treatments, although successful, showed no effect on Tregs [109]....
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TL;DR: The relevance of the different metabolites for the immunomodulatory effect of statins is discussed and preclinical results with data from clinical studies that tested statins for the treatment of different inflammatory diseases are connected.
Abstract: Despite major advances in recent years, immunosuppressive regimens for multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and graft-versus-host disease still have major adverse effects and immunomodulation rather than immune paralysis would be desirable. Statins inhibit the rate-limiting enzyme of the l-mevalonate pathway, the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. It was shown that blocking the l-mevalonate pathway reduces inflammation through effects on downstream metabolites of the pathway including farnesylpyrophosphates and geranylgeranylpyrophosphates, which are essential for the attachment of GTPases like RhoA, Rac and Ras to the cell membrane. Therefore, l-mevalonate pathway downstream products play critical roles in the different steps of an immune response including immune cell activation, migration, cytokine production, immune metabolism and survival. This review discusses the relevance of the different metabolites for the immunomodulatory effect of statins and connects preclinical results with data from clinical studies that tested statins for the treatment of different inflammatory diseases.
152 citations
TL;DR: The mechanism of how Jak-STAT signaling in T cells defines the authors' immune responses in the battle against foreign pathogens is discussed, leading to autoimmunity, allergic diseases, and cancer.
Abstract: The Jak-STAT pathway is one of many pleiotropic signaling pathways that plays an important role in organismal development and in response to changing environmental cues. As a key signaling cascade for cytokines and growth factors, Jak-STAT plays central role in the innate and adaptive immune system. Cytokines control the stability, commitment, and maturation of cytotoxic and helper T cells, parts of the adaptive immune system that mediate immunity to pathogens and are linked to inflammatory diseases. Dysregulation of Jak-STAT protein expression or function leads to autoimmunity, allergic diseases, and cancer. Because of their central role in these responses, Jak and STAT molecules have been targeted to develop therapeutics. This review extensively discusses the mechanism of how Jak-STAT signaling in T cells defines our immune responses in the battle against foreign pathogens.
41 citations
TL;DR: Results indicate that GL has a strong neuroprotective effect on EAE mice by reducing HMGB1 expression and release and thus can be used to treat central nervous system inflammatory diseases, such as MS.
Abstract: The inflammatory mediator high-mobility group box 1 (HMGB1) plays a critical role in the pathogenesis of human multiple sclerosis (MS) and mouse experimental autoimmune encephalomyelitis (EAE). Glycyrrhizin (GL), a glycoconjugated triterpene extracted from licorice root, has the ability to inhibit the functions of HMGB1; however, GL's function against EAE has not been thoroughly characterized to date. To determine the benefit of GL as a modulator of neuroinflammation, we used an in vivo study to examine GL's effect on EAE along with primary cultured cortical neurons to study the GL effect on HMGB1 release. Treatment of EAE mice with GL from onset to the peak stage of disease resulted in marked attenuation of EAE severity, reduced inflammatory cell infiltration and demyelination, decreased tumor necrosis factor-alpha (TNF-α), IFN-γ, IL-17A, IL-6, and transforming growth factor-beta 1, and increased IL-4 both in serum and spinal cord homogenate. Moreover, HMGB1 levels in different body fluids were reduced, accompanied by a decrease in neuronal damage, activated astrocytes and microglia, as well as HMGB1-positive astrocytes and microglia. GL significantly reversed HMGB1 release into the medium induced by TNF-α stimulation in primary cultured cortical neurons. Taken together, the results indicate that GL has a strong neuroprotective effect on EAE mice by reducing HMGB1 expression and release and thus can be used to treat central nervous system inflammatory diseases, such as MS.
39 citations
Cites background from "Neither T-helper type 2 nor Foxp3 +..."
...Many MS/EAE treatments increase Treg cells, which have been found to be efficacious, while other treatments, although successful, have shown no effects on these cells (45)....
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TL;DR: It is demonstrated that 2ccPA protected oligodendrocytes via suppression of the mitochondrial apoptosis pathway and may be a promising compound for the development of new drugs to treat demyelinating disease and ameliorate the symptoms of multiple sclerosis.
Abstract: Multiple sclerosis is a neuroinflammatory demyelinating and neurodegenerative disease of the central nervous system characterized by recurrent and progressive demyelination/remyelination cycles, neuroinflammation, oligodendrocyte loss, demyelination, and axonal degeneration. Cyclic phosphatidic acid (cPA) is a natural phospholipid mediator with a unique cyclic phosphate ring structure at the sn-2 and sn-3 positions of the glycerol backbone. We reported earlier that cPA elicits a neurotrophin-like action and protects hippocampal neurons from ischemia-induced delayed neuronal death. We designed, chemically synthesized, and metabolically stabilized derivatives of cPA: 2-carba-cPA (2ccPA), a synthesized compound in which one of the phosphate oxygen molecules is replaced with a methylene group at the sn-2 position. In the present study, we investigated whether 2ccPA exerts protective effects in oligodendrocytes and suppresses pathology in the two most common mouse models of multiple sclerosis. To evaluate whether 2ccPA has potential beneficial effects on the pathology of multiple sclerosis, we investigated the effects of 2ccPA on oligodendrocyte cell death in vitro and administrated 2ccPA to mouse models of experimental autoimmune encephalomyelitis (EAE) and cuprizone-induced demyelination. We demonstrated that 2ccPA suppressed the CoCl2-induced increase in the Bax/Bcl-2 protein expression ratio and phosphorylation levels of p38MAPK and JNK protein. 2ccPA treatment reduced cuprizone-induced demyelination, microglial activation, NLRP3 inflammasome, and motor dysfunction. Furthermore, 2ccPA treatment reduced autoreactive T cells and macrophages, spinal cord injury, and pathological scores in EAE, the autoimmune multiple sclerosis mouse model. We demonstrated that 2ccPA protected oligodendrocytes via suppression of the mitochondrial apoptosis pathway. Also, we found beneficial effects of 2ccPA in the multiperiod of cuprizone-induced demyelination and the pathology of EAE. These data indicate that 2ccPA may be a promising compound for the development of new drugs to treat demyelinating disease and ameliorate the symptoms of multiple sclerosis.
36 citations
Cites background from "Neither T-helper type 2 nor Foxp3 +..."
...Extensive research regarding the detailed mechanisms underlying immunemediated demyelination in multiple sclerosis has been conducted using EAE model mice [4, 5]....
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...The most commonly studied animal models of multiple sclerosis are the autoimmune experimental autoimmune encephalomyelitis (EAE) model [4, 5] and the cuprizone (bis-cyclohexanone-oxalyldihydrazone, CPZ)induced demyelination model [6, 7]....
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References
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TL;DR: It is shown that oral atorvastatin prevented or reversed chronic and relapsing paralysis and has pleiotropic immunomodulatory effects involving both APC and T-cell compartments.
Abstract: Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which are approved for cholesterol reduction, may also be beneficial in the treatment of inflammatory diseases. Atorvastatin (Lipitor) was tested in chronic and relapsing experimental autoimmune encephalomyelitis, a CD4(+) Th1-mediated central nervous system (CNS) demyelinating disease model of multiple sclerosis. Here we show that oral atorvastatin prevented or reversed chronic and relapsing paralysis. Atorvastatin induced STAT6 phosphorylation and secretion of Th2 cytokines (interleukin (IL)-4, IL-5 and IL-10) and transforming growth factor (TGF)-beta. Conversely, STAT4 phosphorylation was inhibited and secretion of Th1 cytokines (IL-2, IL-12, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha) was suppressed. Atorvastatin promoted differentiation of Th0 cells into Th2 cells. In adoptive transfer, these Th2 cells protected recipient mice from EAE induction. Atorvastatin reduced CNS infiltration and major histocompatibility complex (MHC) class II expression. Treatment of microglia inhibited IFN-gamma-inducible transcription at multiple MHC class II transactivator (CIITA) promoters and suppressed class II upregulation. Atorvastatin suppressed IFN-gamma-inducible expression of CD40, CD80 and CD86 co-stimulatory molecules. l-Mevalonate, the product of HMG-CoA reductase, reversed atorvastatin's effects on antigen-presenting cells (APC) and T cells. Atorvastatin treatment of either APC or T cells suppressed antigen-specific T-cell activation. Thus, atorvastatin has pleiotropic immunomodulatory effects involving both APC and T-cell compartments. Statins may be beneficial for multiple sclerosis and other Th1-mediated autoimmune diseases.
1,082 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background or methods in this paper
...myocarditis [5,6], experimental systemic lupus erythematosus [7] and experimental autoimmune encephalomyelitis (EAE) [2,8-10], the animal model for multiple sclerosis (MS)....
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...These doses have been previously shown to prevent EAE [2]....
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...Besides their metabolic properties, statins attracted interest for their immunomodulatory potential [2]....
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...We observed that in vivo AT treatment during EAE inhibited proliferation of myelin-specific T cells upon restimulation ex vivo [2,8] (Figure 4a), suggesting that these myelin-reactive cells expanded less in AT-treated mice post vaccination....
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...) was brought into suspension in phosphate-buffered saline as described previously [2]....
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TL;DR: The ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.
Abstract: Inflammation and oxidative stress are thought to promote tissue damage in multiple sclerosis. Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for multiple sclerosis treatment. BG00012 is an oral formulation of dimethylfumarate. In a phase II multiple sclerosis trial, BG00012 demonstrated beneficial effects on relapse rate and magnetic resonance imaging markers indicative of inflammation as well as axonal destruction. First we have studied effects of dimethylfumarate on the disease course, central nervous system, tissue integrity and the molecular mechanism of action in an animal model of chronic multiple sclerosis: myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis in C57BL/6 mice. In the chronic phase of experimental autoimmune encephalomyelitis, preventive or therapeutic application of dimethylfumarate ameliorated the disease course and improved preservation of myelin, axons and neurons. In vitro, the application of fumarates increased murine neuronal survival and protected human or rodent astrocytes against oxidative stress. Application of dimethylfumarate led to stabilization of the transcription factor nuclear factor (erythroid-derived 2)-related factor 2, activation of nuclear factor (erythroid-derived 2)-related factor 2-dependent transcriptional activity and accumulation of NADP(H) quinoline oxidoreductase-1 as a prototypical target gene. Furthermore, the immediate metabolite of dimethylfumarate, monomethylfumarate, leads to direct modification of the inhibitor of nuclear factor (erythroid-derived 2)-related factor 2, Kelch-like ECH-associated protein 1, at cysteine residue 151. In turn, increased levels of nuclear factor (erythroid-derived 2)-related factor 2 and reduced protein nitrosylation were detected in the central nervous sytem of dimethylfumarate-treated mice. Nuclear factor (erythroid-derived 2)-related factor 2 was also upregulated in the spinal cord of autopsy specimens from untreated patients with multiple sclerosis. In dimethylfumarate-treated mice suffering from experimental autoimmune encephalomyelitis, increased immunoreactivity for nuclear factor (erythroid-derived 2)-related factor 2 was detected by confocal microscopy in neurons of the motor cortex and the brainstem as well as in oligodendrocytes and astrocytes. In mice deficient for nuclear factor (erythroid-derived 2)-related factor 2 on the same genetic background, the dimethylfumarate mediated beneficial effects on clinical course, axon preservation and astrocyte activation were almost completely abolished thus proving the functional relevance of this transcription factor for the neuroprotective mechanism of action. We conclude that the ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.
936 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background in this paper
...factor (Nrf2) pathway [49,50], it also exerts anti-...
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TL;DR: Investigation of use of oral simvastatin in 30 individuals with relapsing-remitting multiple sclerosis found it to inhibit inflammatory components of multiple sclerosis that lead to neurological disability.
Abstract: Many drugs have been approved for relapsing forms of multiple sclerosis but are only partly effective, are injected, and are expensive. We aimed to investigate use of of oral simvastatin (80 mg) in 30 individuals with relapsing-remitting multiple sclerosis. The mean number of gadolinium-enhancing lesions at months 4, 5, and 6 of treatment was compared with the mean number of lesions noted on pretreatment brain MRI scans. Number and volume of Gd-enhancing lesions declined by 44%, (p<0.0001) and 41% (p=0.0018), respectively. Treatment was well tolerated. Oral simvastatin might inhibit inflammatory components of multiple sclerosis that lead to neurological disability.
475 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background in this paper
...How does this new information impact the potential use of statins in MS [42]? At first glance, nonspecific inhibition of proinflammatory T-cell differentiation in MS may be viewed less advantageously than the active induction of an anti-inflammatory T-cell phenotype [17,18,43]....
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...In the first placebo-controlled trial testing a statin as monotherapy in MS, atorvastatin (AT) significantly reduced the risk of developing new magnetic resonance imaging demyelinating lesions in patients with clinical isolated syndromes, but did not meet its primary endpoint that included reduction in conversion to clinically definite MS [17,18]....
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TL;DR: Reporter T cells primed under Th2 conditions showed sensitive and faithful EGFP expression and maintained endogenous IL-4, and reporter expression demonstrated the evolution of type 2 immunity from tissue lymphocytes and thence to lymph node CD4(+) T cells, which subsequently migrated into tissue.
Abstract: Effector T cells mediate adaptive immunity and immunopathology, but methods for tracking such cells in vivo are limited. We engineered knockin mice expressing IL-4 linked via a viral IRES element with enhanced green fluorescent protein (EGFP). Reporter T cells primed under Th2 conditions showed sensitive and faithful EGFP expression and maintained endogenous IL-4. After Nippostrongylus infection, reporter expression demonstrated the evolution of type 2 immunity from tissue lymphocytes and thence to lymph node CD4(+) T cells, which subsequently migrated into tissue. The appearance of EGFP(+) CD4(+) T cells in tissue, but not in lymph nodes, was Stat6-dependent. Transferred EGFP(+) CD4(+) T cells from infected animals conferred protection against Nippostrongylus to immunodeficient mice. These mice will provide a valuable reagent for assessing immunity in vivo.
439 citations
TL;DR: 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, identifying a central role for these cells in T cell immune modulation of autoimmunity.
Abstract: 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)-beta, 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 T(H)2 cells and CD4+CD25+FoxP3+ regulatory T cells (T(reg)) 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 T(H)17 cell development and promoted both T(H)2 differentiation and expansion of T(reg) 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.
436 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background or result in this paper
...(b) The frequency of CD4+CD25+FoxP3+ regulatory T cells (Tregs) was evaluated by fluorescence-activated cell sorting....
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...However, it was not associated with an increase in CD4+CD25+FoxP3+ Tregs in either STAT6-deficient or wild-type mice....
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...A potential increase in Tregs is therefore unlikely to significantly contribute to the anti-inflammatory effect of statins in CNS autoimmune disease....
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...Induction of CD4+CD25+FoxP3+ Tregs was evaluated using a FACS staining kit by eBioscience....
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...Whether statins solely inhibit encephalitogenic T-cell differentiation or whether they may actively induce regulatory T-cell populations such as Th2 cells or Foxp3+ Tregs, considered a desirable goal in treatment of MS, thus remains to be investigated....
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