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: There are good scientific rationales for the use of combination therapy in multiple sclerosis, and the pharmacologic principles for evaluating and understanding their actions are available.
Abstract: Purpose of reviewTo outline the scientific rationale for combination therapy in multiple sclerosis and to discuss the evidence for combination treatment strategies from animal models and clinical trials of multiple sclerosis.Recent findingsExperiments conducted in experimental autoimmune encephalomy
47 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background in this paper
...In general, for two agents to exert synergistic benefit, distinct mechanisms of action are desirable, while employing the same mechanism may increase the risk of antagonism [46]....
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University of California, San Francisco1, Oregon Health & Science University2, Cleveland Clinic3, Washington University in St. Louis4, McGill University5, St. Joseph's Hospital and Medical Center6, University of Texas Southwestern Medical Center7, University of Rochester8, University of Southern California9, Yale University10, University at Buffalo11, Johns Hopkins University12, Icahn School of Medicine at Mount Sinai13, National Institutes of Health14
TL;DR: This study provided Class II evidence that atorvastatin did not reduce the proportion of patients with CIS meeting imaging and clinical criteria for starting immunomodulating therapy after 12 months, compared to placebo and associated with a reduced risk for developing new T2 lesions.
Abstract: Objective: To test efficacy and safety of atorvastatin in subjects with clinically isolated syndrome (CIS). Methods: Subjects with CIS were enrolled in a phase II, double-blind, placebo-controlled, 14-center randomized trial testing 80 mg atorvastatin on clinical and brain MRI activity. Brain MRIs were performed quarterly. The primary endpoint (PEP) was development of3 new T2 lesions, or one clinical relapse within 12 months. Subjects meeting the PEP were offered additional weekly interferon -1a (IFN-1a). Results: Due to slow recruitment, enrollment was discontinued after 81 of 152 planned subjects with CIS were randomized and initiated study drug. Median (interquartile range) numbers of T2 and gadolinium-enhancing (Gd) lesions were 15.0 (22.0) and 0.0 (0.0) at baseline. A total of 53.1% of atorvastatin recipients (n 26/49) met PEP compared to 56.3% of placebo recipients (n 18/32) (p 0.82). Eleven atorvastatin subjects (22.4%) and 7 placebo subjects (21.9%) met the PEP by clinical criteria. Proportion of subjects who did not develop new T2 lesions up to month 12 or to starting IFN-1a was 55.3% in the atorvastatin and 27.6% in the placebo group (p 0.03). Likelihood of remaining free of new T2 lesions was significantly greater in the atorvastatin group compared with placebo (odds ratio [OR] 4.34, p 0.01). Likelihood of remaining free of Gd lesions tended to be higher in the atorvastatin group (OR 2.72, p 0.11). Overall, atorvastatin was well tolerated. No clear antagonistic effect of atorvastatin plus IFN-1a was observed on MRI measures. Conclusion: Atorvastatin treatment significantly decreased development of new brain MRI T2 lesion activity, although it did not achieve the composite clinical and imaging PEP. Classification of Evidence: This study provided Class II evidence that atorvastatin did not reduce the proportion of patients with CIS meeting imaging and clinical criteria for starting immunomodulating therapy after 12 months, compared to placebo. In an analysis of a secondary endpoint (Class III), atorvastatin was associated with a reduced risk for developing new T2 lesions. Neurology ® 2012;78:1171–1178
43 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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41 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background in this paper
...Statins are inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase that are widely prescribed to lower serum cholesterol [1]....
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TL;DR: RSV pretreatment was associated with more Treg accumulation, less inflammatory response, and myocardial injury, suggesting that such cardioprotection against IRI was partially mediated by Treg-negative modulation of inflammation response, probably through the HMG-CoA reductase pathway.
Abstract: Objectives CD4+CD25+ regulatory T cells (Tregs) play a key role in the prevention of various inflammatory and autoimmune disorders by suppressing immune responses. The beneficial effect of statins on myocardial ischemia-reperfusion injury (IRI) depends in part on their immunomodulatory and anti-inflammatory mechanisms. We aimed to determine whether Tregs contribute to statin-induced cardioprotection against myocardial IRI. Methods Thirty-two rats were divided into four groups: sham, ischemia-reperfusion (IR), rosuvastatin (RSV)/IR, and mevalonic acid (MVA)+RSV/IR. Myocardial IR was induced by a 30-min coronary occlusion, followed by a 48-h reperfusion. RSV (5 mg/kg) was administered intravenously 18 h before IR. The rats were killed after 48-h reperfusion. Serum cardiac troponin I (cTnI) was measured by ELISA, infiltration of inflammatory cells in myocardium by hematoxylin and eosin staining, expression of FoxP3 protein by western blotting, accumulation of Tregs in myocardium by immunohistochemical examination, and infarct size by TTC staining. Results Significant elevation in serum cTnI, enlarged infarct size, and marked infiltration of inflammatory cells in myocardium were observed in the IR group. The administration of RSV significantly reduced the serum cTnI level, attenuated the accumulation of inflammatory cells, decreased infarct size, and increased the FoxP3 expression and Treg accumulation in myocardium compared with the IR group. The combination of RSV and MVA pretreatment partially abolished the anti-inflammatory and infarct size-limiting effects and completely reversed Treg accumulation in myocardium induced by RSV. The accumulation of inflammatory cells was negatively correlated with FoxP3 expression and Treg accumulation in the ischemic myocardium. Conclusion RSV pretreatment was associated with more Treg accumulation, less inflammatory response, and myocardial injury, suggesting that such cardioprotection against IRI was partially mediated by Treg-negative modulation of inflammation response, probably through the HMG-CoA reductase pathway.
40 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background 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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TL;DR: Although histological grading suggested mildly decreased inflammation in the high dose treated group, the equivalence of cytokine expression in all groups suggests that the statins may not modulate IRBP induced uveoretinitis.
Abstract: Aim: To investigate the effect of atorvastatin (Lipitor), a commonly used drug for dyslipidaemia in experimental autoimmune uveitis (EAU). Methods: 48 B10-RIII mice were immunised with human interphotoreceptor retinoid binding protein (IRBP) peptide p161–180. They were divided into three groups of 16 each and treated orally once daily for 14 days; group one received phosphate buffered saline (control group), group two received 1 mg/kg of atorvastatin (low dose group), and group three received 10 mg/kg (high dose). On day 14 lymph nodes, spleens, and right eyes were harvested. RNA was extracted from lymph nodes for RNase protection assay (RPA) to determine proinflammatory (IL-1α and IL-1β), Th1 (TNF-α, IL-2, IL-12), and Th2 (IL-4, IL-5, and IL-10) cytokine levels. Protein was extracted from spleens for western blot to detect the expression of phosphorylated signal transducer and activator of transcription (STAT) 4 and STAT6. The severity of inflammation in enucleated eyes was graded by a masked observer. Paired t test was performed for the mean difference in histological scoring between treated groups and the immunised control group. Results: Surprisingly, atorvastatin did not modulate the immune response. The proinflammatory cytokines, IL-1α and IL-1β, and Th1 cytokines, TNF-α and IL-2, were upregulated equally in control and atorvastatin treated groups. IL-12 and Th2 cytokines were not upregulated in all three groups. Western blot analysis showed high levels of phosphorylated STAT4, but not STAT6 protein in the control and atorvastatin treated groups. Mean differences in histological scoring between treated groups and the immunised control group were not statistically significant. Conclusions: Atorvastatin treatment had no effect on Th1 and Th2 cytokine transcription. Although histological grading suggested mildly decreased inflammation in the high dose treated group, the equivalence of cytokine expression in all groups suggests that the statins may not modulate IRBP induced uveoretinitis.
33 citations
"Neither T-helper type 2 nor Foxp3 +..." refers background in this paper
...Statins are clinically beneficial in various models of autoimmune diseases, such as experimental arthritis [3], experimental autoimmune uveoretinitis [4], experimental autoimmune...
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