Distribution of Foxp3+ T-regulatory cells in experimental autoimmune neuritis rats

Immune dysregulation in chronic inflammatory demyelinating polyneuropathy

OBJECTIVE

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an autoimmune disorder of the peripheral nerves with an incompletely understood underlying pathophysiology. This investigation focused on defining B and T cell frequencies, T cell functional capacity and innate immune system analysis in patients with CIDP.

METHODS

By using multi-parameter flow cytometry, we examined the phenotype and function of PBMCs in 25 CIDP patients who were relatively clinically stable on treatment who met EFNS/PNS criteria, 21 patients with genetically confirmed hereditary neuropathy and 25 healthy controls. We also evaluated the regulatory T cell (Treg) inhibitory capacity by co-culturing Treg and effector T cells.

RESULTS

Proinflammatory CD4 T cells, especially type 1 helper T cell (Th1) and CD8 T cells in patients with CIDP were found to have an enhanced capacity to produce inflammatory cytokines. There was no difference in frequency of Th17 regulatory cells in CIDP patients versus healthy controls, however, Treg function was impaired in CIDP patients. There was no remarkable difference in innate immune system measures. Within B cell subsets, transitional cell frequency was decreased in CIDP patients.

INTERPRETATION

Patients with CIDP clinically stable on treatment continued to show evidence of a proinflammatory state with impaired Treg function. This potentially implies an inadequate suppression of ongoing inflammation not addressed by standard of care therapies as well as persistent activity of disease while on treatment. Targeting T cells, especially inhibiting Th1 and polyfunctional CD8 T cells or improving Treg cell function could be potential targets for future therapeutic research.

Deciphering immune mechanisms in chronic inflammatory demyelinating polyneuropathies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an autoimmune disease of the peripheral nerves that presents with either chronic progression or relapsing disease. Recent studies in samples from patients with CIDP and mouse models have delineated how defects in central (thymic) and peripheral (extrathymic) immune tolerance mechanisms can cause PNS autoimmunity. Notably, nerve parenchymal cells actively contribute to local autoimmunity and also control disease outcome. Here, we outline how emerging technologies increasingly enable an integrated view of how immune cells and PNS parenchymal cells communicate in CIDP. We also relate the known heterogeneity of clinical presentation with specific underlying mechanisms. For example, a severe subtype of CIDP with tremor is associated with pathogenic IgG4 autoantibodies against nodal and paranodal proteins. An improved understanding of pathogenic mechanisms in CIDP will form the basis for more effective mechanism-based therapies.

Effect of fasudil on experimental autoimmune neuritis and its mechanisms of action

This study aimed to investigate the therapeutic effect of fasudil on treating experimental autoimmune neuritis (EAN). Twenty-four EAN mice were randomly assigned to fasudil treatment (Fasudil group) or saline treatment (EAN model group) for 28 days. Clinical symptom score was evaluated every other day; inflammatory cell infiltration, demyelination, anti-myelin basic protein (MBP), inflammatory cytokines, inducible nitric oxide synthase (iNOS), and arginase-1 were detected in sciatic nerves at day 28. Th1, Th2, Th17, and Tregs proportions in splenocytes were detected at day 28. Clinical symptom score was found to be attenuated in the Fasudil group compared to the EAN model group from day 12 to day 28. Sciatic nerve inflammatory cell counts by HE staining and demyelination by luxol fast blue staining were both reduced, while MBP was increased in the Fasudil group compared to the EAN model group at day 28. Interferon γ (IFN-γ) and interleukin (IL)-17 were reduced, while IL-4 and IL-10 were elevated in the Fasudil group at day 28. Sciatic nerve M1 macrophages marker iNOS was decreased while M2 macrophages marker arginase-1 was increased in the Fasudil group at day 28. CD4⁺IFN-γ⁺ (Th1) and CD4⁺IL-17⁺ (Th17) cell proportions were both decreased, CD4⁺IL-4⁺ (Th2) cell proportion was similar, while CD25+FOXP3+ (Treg) cell proportion in splenocytes was increased in the Fasudil group. In summary, fasudil presented a good therapeutic effect for treating EAN by attenuating Th1/Th17 cells and promoting Tregs activation as well as M2 macrophages polarization.

Class I PI3K inhibitor ZSTK474 attenuates experimental autoimmune neuritis by decreasing the frequency of Th1/Th17 cells and reducing the production of proinflammatory cytokines

The Class I phosphatidylinositol 3-kinase inhibitor, 2-(2-difluoromethy lbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (ZSTK474), has anti-inflammatory and immunoregulatory properties. However, whether it can be used to treat Guillain-Barré syndrome (GBS)-a neuroinflammatory disorder-is unknown. We induced experimental autoimmune neuritis (EAN) in Lewis rats, an established model of GBS. Orally administered ZSTK474 decreased neurological deficits in the GBS model, as demonstrated by diminished inflammatory cell infiltration, and ameliorated demyelination of sciatic nerves. Additionally, ZSTK474 decreased the number of Th1/Th17 cells and levels of the proinflammatory cytokines interleukin (IL)-1α, IL-1β, IL-17, IL-23, interferon-γ, and tumor necrosis factor-α. We propose that the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathway likely contributed to the neuroprotective effect of ZSTK474. ZSTK474 effectively decreases the frequency of Th1/Th17 cells, thereby reducing the production of proinflammatory cytokines and successfully alleviating the symptoms of EAN. Thus, the neuroprotective effect of ZSTK474 indicates its potential utility as anti-inflammatory therapy for GBS.

Fingolimod promotes blood-nerve barrier properties in vitro

OBJECTIVE

The main effect of fingolimod is thought to be functional antagonism of lymphocytic S1P1 receptors and the prevention of lymphocyte egress from lymphoid tissues, thereby reducing lymphocyte infiltration into the nervous system. However, a growing number of reports suggest that fingolimod also has a direct effect on several cell types in the nervous system. Although we previously reported that fingolimod enhances blood-brain barrier (BBB) functions, there have been no investigations regarding the blood-nerve barrier (BNB). In this study, we examine how fingolimod affects the BNB.

METHODS

An immortalized human peripheral nerve microvascular endothelial cell line (HPnMEC) was used to evaluate BNB barrier properties. We examined tight junction proteins and barrier functions of HPnMECs in conditioned medium with or without fingolimod-phosphate and blood sera from patients with typical chronic inflammatory demyelinating polyneuropathy (CIDP).

RESULTS

Incubation with fingolimod-phosphate increased levels of claudin-5 mRNA and protein as well as TEER values in HPnMECs. Conversely, typical CIDP sera decreased claudin-5 mRNA/protein levels and TEER values in HPnMECs; however, pretreatment with fingolimod-phosphate inhibited the effects of the typical CIDP sera.

CONCLUSIONS

Fingolimod-phosphate directly modifies the BNB and enhances barrier properties. This mechanism may be a viable therapeutic target for CIDP, and fingolimod may be useful in patients with typical CIDP who have severe barrier disruption.

Interleukin-10 Modulation of Virus Clearance and Disease in Mice with Alphaviral Encephalomyelitis

Alphaviruses are an important cause of mosquito-borne outbreaks of arthritis, rash, and encephalomyelitis. Previous studies in mice with a virulent strain (neuroadapted SINV [NSV]) of the alphavirus Sindbis virus (SINV) identified a role for Th17 cells and regulation by interleukin-10 (IL-10) in the pathogenesis of fatal encephalomyelitis (K. A. Kulcsar, V. K. Baxter, I. P. Greene, and D. E. Griffin, Proc Natl Acad Sci U S A 111:16053-16058, 2014, https://doi.org/10.1073/pnas.1418966111). To determine the role of virus virulence in generation of immune responses, we analyzed the modulatory effects of IL-10 on disease severity, virus clearance, and the CD4+ T cell response to infection with a recombinant strain of SINV of intermediate virulence (TE12). The absence of IL-10 during TE12 infection led to longer morbidity, more weight loss, higher mortality, and slower viral clearance than in wild-type mice. More severe disease and impaired virus clearance in IL-10-/- mice were associated with more Th1 cells, fewer Th2 cells, innate lymphoid type 2 cells, regulatory cells, and B cells, and delayed production of antiviral antibody in the central nervous system (CNS) without an effect on Th17 cells. Therefore, IL-10 deficiency led to more severe disease in TE12-infected mice by increasing Th1 cells and by hampering development of the local B cell responses necessary for rapid production of antiviral antibody and virus clearance from the CNS. In addition, the shift from Th17 to Th1 responses with decreased virus virulence indicates that the effects of IL-10 deficiency on immunopathologic responses in the CNS during alphavirus infection are influenced by virus strain.IMPORTANCE Alphaviruses cause mosquito-borne outbreaks of encephalomyelitis, but determinants of outcome are incompletely understood. We analyzed the effects of the anti-inflammatory cytokine IL-10 on disease severity and virus clearance after infection with an alphavirus strain of intermediate virulence. The absence of IL-10 led to longer illness, more weight loss, more death, and slower viral clearance than in mice that produced IL-10. IL-10 influenced development of disease-causing T cells and entry into the brain of B cells producing antiviral antibody. The Th1 pathogenic cell subtype that developed in IL-10-deficient mice infected with a less virulent virus was distinct from the Th17 subtype that developed in response to a more virulent virus, indicating a role for virus strain in determining the immune response. Slow production of antibody in the nervous system led to delayed virus clearance. Therefore, both the virus strain and the host response to infection are important determinants of outcome.

Novel pathomechanisms in inflammatory neuropathies

Inflammatory neuropathies are rare autoimmune-mediated disorders affecting the peripheral nervous system. Considerable progress has recently been made in understanding pathomechanisms of these disorders which will be essential for developing novel diagnostic and therapeutic strategies in the future. Here, we summarize our current understanding of antigenic targets and the relevance of new immunological concepts for inflammatory neuropathies. In addition, we provide an overview of available animal models of acute and chronic variants and how new diagnostic tools such as magnetic resonance imaging and novel therapeutic candidates will benefit patients with inflammatory neuropathies in the future. This review thus illustrates the gap between pre-clinical and clinical findings and aims to outline future directions of development.

Resolvin D1 Programs Inflammation Resolution by Increasing TGF-β Expression Induced by Dying Cell Clearance in Experimental Autoimmune Neuritis

Experimental autoimmune neuritis (EAN) is the animal model of human acute inflammatory demyelinating polyradiculoneuropathies (AIDP), an auto-immune inflammatory demyelination disease of the peripheral nervous system (PNS) and the world's leading cause of acute autoimmune neuromuscular paralysis. EAN and AIDP are characterized by self-limitation with spontaneous recovery; however, endogenous pathways that regulate inflammation resolution in EAN and AIDP remain elusive. A pathway of endogenous mediators, especially resolvins and clearance of apoptotic cells, may be involved. Here, we determined that resolvin D1 (RvD1), its synthetic enzyme, and its receptor were greatly increased in PNS during the recovery stage of EAN. Both endogenous and exogenous RvD1 increased regulatory T (Treg) cell and anti-inflammatory macrophage counts in PNS, enhanced inflammation resolution, and promoted disease recovery in EAN rats. Moreover, RvD1 upregulated the transforming growth factor-β (TGF-β) level and pharmacologic inhibition of TGF-β signaling suppressed RvD1-induced Treg cell counts, but not anti-inflammatory macrophage counts, and RvD1-improved inflammation resolution and disease recovery in EAN rats. Mechanistically, the RvD1-enhanced macrophage phagocytosis of apoptotic T cells leading to reduced apoptotic T-cell accumulation in PNS induced TGF-β production and caused Treg cells to promote inflammation resolution and disease recovery in EAN. Therefore, these data highlight the crucial role of RvD1 as an important pro-resolving molecule in EAN and suggest its potential as a therapeutic target in human neuropathies.

SIGNIFICANCE STATEMENT

Experimental autoimmune neuritis (EAN) is the animal model of human acute inflammatory demyelinating polyradiculoneuropathies, an auto-immune inflammatory demyelination disease of the peripheral nervous system (PNS) and the world's leading cause of acute autoimmune neuromuscular paralysis. Here, we demonstrated that resolvin D1 (RvD1) promoted macrophage phagocytosis of apoptotic T cells in PNS, thereby upregulating transforming growth factor-β by macrophages, increased local Treg cell counts, and finally promoted inflammation resolution and disease recovery in EAN. These data highlight the crucial role of RvD1 as an important pro-resolving molecule in EAN and suggest that it has potential as a therapeutic target in human neuritis.

Programmed Death Ligand 1 Plays a Neuroprotective Role in Experimental Autoimmune Neuritis by Controlling Peripheral Nervous System Inflammation of Rats

Programmed death 1 (PD-1; CD279), a member of the CD28 family, is an inhibitory receptor on T cells and is responsible for T cell dysfunction in infectious diseases and cancers. The ligand for PD-1, programmed death ligand 1 (PD-L1; also known as B7-H1, CD274), is a member of the B7 family. The engagement of PD-1 with programmed death ligand can downregulate autoreactive T cells that participate in multiple autoimmune diseases. Experimental autoimmune neuritis (EAN) is an animal model of Guillain-Barré syndrome, and the pathogenesis of EAN is mediated principally through T cells and macrophages. In this study, we investigated the effects of PD-L1 in EAN rats. For preventative and therapeutic management, we administered PD-L1, which successfully decreased the severity of EAN; it alleviated the neurologic course of EAN, as well as inhibited the infiltration of inflammatory cells and demyelination of sciatic nerves. Our data revealed that PD-L1 treatment inhibited lymphocyte proliferation and altered T cell differentiation by inducing decreases in IFN-γ⁺CD4⁺ Th1 cells and IL-17⁺CD4⁺ Th17 cells and increases in IL-4⁺CD4⁺ Th2 cells and Foxp3⁺CD4⁺ regulatory T cells. The expression levels of p-STAT3 and Foxp3 were significantly different in PD-L1-treated groups compared with the control group. Additionally, PD-L1 regulated the expression of Foxp3 and p-STAT3 in EAN, probably by inhibiting PI3K/AKT/mTOR signaling expression. In summary, PD-L1 is a potentially useful agent for the treatment of EAN because of its anti-inflammatory and neuroprotective effects.

Regulatory T and B lymphocytes in a spontaneous autoimmune polyneuropathy

B7-2(-/-) non-obese diabetic (NOD) mice develop a spontaneous autoimmune polyneuropathy (SAP) that mimics the progressive form of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). In this study, we focused on the role of regulatory T cells (Tregs ) and regulatory B cells (Bregs ) in SAP. We found that deletion of B7-2 in female NOD mice led to a lower frequency and number of Tregs and Bregs in spleens and lymph nodes. Tregs but not Bregs suppressed antigen-stimulated splenocyte proliferation, whereas Bregs inhibited the T helper type 1 (Th1) cytokine response. Both Tregs and Bregs induced an increase in CD4(+) interleukin (IL)-10(+) cells, although less effectively in the absence of B7-2. Adoptive transfer studies revealed that Tregs , but not Bregs , suppressed SAP, while Bregs attenuated disease severity when given prior to symptom onset. B cell deficiency in B cell-deficient (muMT)/B7-2(-/-) NOD mice prevented the development of SAP, which would indicate that the pathogenic role of B cells predominates over its regulatory role in this model. We conclude that Bregs and Tregs control the immunopathogenesis and progression of SAP in a non-redundant fashion, and that therapies aimed at expansion of Bregs and Tregs may be an effective approach in autoimmune neuropathies.

Forced Exercise Preconditioning Attenuates Experimental Autoimmune Neuritis by Altering Th1 Lymphocyte Composition and Egress

A short-term exposure to moderately intense physical exercise affords a novel measure of protection against autoimmune-mediated peripheral nerve injury. Here, we investigated the mechanism by which forced exercise attenuates the development and progression of experimental autoimmune neuritis (EAN), an established animal model of Guillain–Barré syndrome. Adult male Lewis rats remained sedentary (control) or were preconditioned with forced exercise (1.2 km/day × 3 weeks) prior to P2-antigen induction of EAN. Sedentary rats developed a monophasic course of EAN beginning on postimmunization day 12.3 ± 0.2 and reaching peak severity on day 17.0 ± 0.3 (N = 12). By comparison, forced-exercise preconditioned rats exhibited a similar monophasic course but with significant (p < .05) reduction of disease severity. Analysis of popliteal lymph nodes revealed a protective effect of exercise preconditioning on leukocyte composition and egress. Compared with sedentary controls, forced exercise preconditioning promoted a sustained twofold retention of P2-antigen responsive leukocytes. The percentage distribution of pro-inflammatory (T_h1) lymphocytes retained in the nodes from sedentary EAN rats (5.1 ± 0.9%) was significantly greater than that present in nodes from forced-exercise preconditioned EAN rats (2.9 ± 0.6%) or from adjuvant controls (2.0 ± 0.3%). In contrast, the percentage of anti-inflammatory (T_h2) lymphocytes (7–10%) and that of cytotoxic T lymphocytes (∼20%) remained unaltered by forced exercise preconditioning. These data do not support an exercise-inducible shift in T_h1:T_h2 cell bias. Rather, preconditioning with forced exercise elicits a sustained attenuation of EAN severity, in part, by altering the composition and egress of autoreactive proinflammatory (T_h1) lymphocytes from draining lymph nodes.

FoxP3+ regulatory T cells determine disease severity in rodent models of inflammatory neuropathies

Inflammatory neuropathies represent disabling human autoimmune disorders with considerable disease variability. Animal models provide insights into defined aspects of their disease pathogenesis. Forkhead box P3 (FoxP3)+ regulatory T lymphocytes (Treg) are anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders. Dysfunction or a reduced frequency of Tregs have been associated with different human autoimmune disorders. We here analyzed the functional relevance of Tregs in determining disease manifestation and severity in murine models of autoimmune neuropathies. We took advantage of the DEREG mouse system allowing depletion of Treg with high specificity as well as anti-CD25 directed antibodies to deplete Tregs in mice in actively induced experimental autoimmune neuritis (EAN). Furthermore antibody-depletion was performed in an adoptive transfer model of chronic neuritis. Early Treg depletion increased clinical EAN severity both in active and adoptive transfer chronic neuritis. This was accompanied by increased proliferation of myelin specific T cells and histological signs of peripheral nerve inflammation. Late stage Treg depletion after initial disease manifestation however did not exacerbate inflammatory neuropathy symptoms further. We conclude that Tregs determine disease severity in experimental autoimmune neuropathies during the initial priming phase, but have no major disease modifying function after disease manifestation. Potential future therapeutic approaches targeting Tregs should thus be performed early in inflammatory neuropathies.

Targeting the molecular and cellular interactions of the bone marrow niche in immunologic disease

Recent investigations have expanded our knowledge of the regulatory bone marrow (BM) niche, which is critical in maintaining and directing hematopoietic stem cell (HSC) self-renewal and differentiation. Osteoblasts, mesenchymal stem cells (MSCs), and CXCL12-abundant reticular (CAR) cells are niche components in close association with HSCs and have been more clearly defined in immune cell function and homeostasis. Importantly, cellular inhabitants of the BM niche signal through G protein-coupled surface receptors (GPCRs) for various appropriate immune functions. In this article, recent literature on BM niche inhabitants (HSCs, osteoblasts, MSCs, CAR cells) and their GPCR mechanistic interactions are reviewed for better understanding of the BM cells involved in immune development, immunologic disease, and current immune reconstitution therapies.

Erythropoietin-derived nonerythropoietic peptide ameliorates experimental autoimmune neuritis by inflammation suppression and tissue protection

Experimental autoimmune neuritis (EAN) is an autoantigen-specific T-cell-mediated disease model for human demyelinating inflammatory disease of the peripheral nervous system. Erythropoietin (EPO) has been known to promote EAN recovery but its haematopoiesis stimulating effects may limit its clinic application. Here we investigated the effects and potential mechanisms of an EPO-derived nonerythropoietic peptide, ARA 290, in EAN. Exogenous ARA 290 intervention greatly improved EAN recovery, improved nerve regeneration and remyelination, and suppressed nerve inflammation. Furthermore, haematopoiesis was not induced by ARA 290 during EAN treatment. ARA 290 intervention suppressed lymphocyte proliferation and altered helper T cell differentiation by inducing increase of Foxp3+/CD4+ regulatory T cells and IL-4+/CD4+ Th2 cells and decrease of IFN-γ+/CD4+ Th1 cells in EAN. In addition, ARA 290 inhibited inflammatory macrophage activation and promoted its phagocytic activity. In vitro, ARA 290 was shown to promote Schwann cell proliferation and inhibit its inflammatory activation. In summary, our data demonstrated that ARA 290 could effectively suppress EAN by attenuating inflammation and exerting direct cell protection, indicating that ARA 290 could be a potent candidate for treatment of autoimmune neuropathies.

Alloanergization of human T cells results in expansion of alloantigen-specific CD8(+) CD28(-) suppressor cells

Allostimulation with concurrent costimulatory blockade induces alloantigen-specific hyporesponsiveness in responder T cells ("alloanergization"). Alloanergized responder cells also acquire alloantigen-specific suppressive activity, suggesting this strategy induces active immune tolerance. While this acquired suppressive activity is mediated primarily by CD4(+) FOXP3(+) cells, other cells, most notably CD8(+) suppressor cells, have also been shown to ameliorate human alloresponses. To determine whether alloanergization expands CD8(+) cells with allosuppressive phenotype and function, we used mixed lymphocyte cultures in which costimulatory blockade was provided by belatacept, an FDA-approved, second-generation CTLA-4-immunoglobulin fusion protein that blocks CD28-mediated costimulation, as an in vitro model of HLA-mismatched transplantation. This strategy resulted in an eightfold expansion of CD8(+) CD28(-) T cells which potently and specifically suppressed alloresponses of both CD4(+) and CD8(+) T cells without reducing the frequency of a range of functional pathogen-specific T cells. This CD8-mediated allosuppression primarily required cell-cell contact. In addition, we observed expansion of CD8(+) CD28(-) T cells in vivo in patients undergoing alloanergized HLA-mismatched bone marrow transplantation. Use of costimulatory blockade-mediated alloanergization to expand allospecific CD8(+) CD28(-) suppressor cells merits exploration as an approach to inducing or supporting immune tolerance to alloantigens after allogeneic transplantation.

HDAC inhibitor MS-275 attenuates the inflammatory reaction in rat experimental autoimmune prostatitis

BACKGROUND

Experimental autoimmune prostatitis (EAP) is an autoimmune inflammatory disease of male sex accessory glands and is characterized by a cellular and humoral prostate-specific autoimmune response. EAP shares important clinical and immunological features with human chronic prostatitis and chronic pelvic pain syndrome. MS-275, a potent histone deacetylase inhibitor, has promising anti-inflammatory activities and might be a new agent in the therapy of prostate inflammation.

METHODS

EAP rats were treated with MS-275 (5 mg/kg, i.p.) once daily. Using immunohistochemistry and PCR assay, we determined immune cellular responses and infiltration into the prostate glands, and changes of mRNA levels of representative inflammatory molecules in prostate tissue. Changes in Foxp3(+) CD4(+) cell populations of lymph nodes and peripheral blood were analyzed by flow cytometry. Additionally, direct anti-inflammatory effects of MS-275 were investigated in vitro with a macrophage cell line.

RESULTS

MS-275 treatment significantly reduced the local accumulation of immune cells and mRNA levels of representative pro-inflammatory molecules in prostate tissue. Furthermore, MS-275 treatment increased percentage of Foxp3(+) CD4(+) Treg cells in lymph nodes and their proportion to CD4(+) cells in peripheral blood, and induced a relative increase of ED2(+) macrophage numbers in EAP prostate. Additional in vitro study showed that MS-275 induced a switch of macrophages from classic M1 to anti-inflammatory M2 phenotype.

CONCLUSIONS

In summary, our data demonstrated that MS-275 could effectively suppress inflammatory reaction in EAP, through suppressing immune cells and pro-inflammatory molecules, and inducing anti-inflammatory immune cells and molecules, which may suggest MS-275 as a potential candidate for treatment of inflammatory prostatitis.

Fingolimod in multiple sclerosis: mechanisms of action and clinical efficacy

Fingolimod, also known as FTY720, has recently been approved by the regulatory authorities in the US, EU, Australia, Russia, among others, for the treatment of relapsing-remitting multiple sclerosis. Fingolimod therefore represents the first oral drug for the treatment of this autoimmune disease of the central nervous system. Fingolimod modulates sphingosine-1 phosphate receptors and has unique immunoregulatory properties. Mechanistic studies from animal models have shown that fingolimod prevents immune cells from exiting from the lymphoid tissue and reaching the inflammatory tissue. Indeed, two phase III studies that laid the basis for fingolimod's approval demonstrated that fingolimod efficiently improves the relapse rate compared to both placebo and one of the standard MS medications. In this review, we will summarize the immunological profile of fingolimod, discuss the possible direct neurobiological effects that have been suggested recently and present the clinical data regarding the efficacy and safety profiles of this promising new drug.

MS-275, an histone deacetylase inhibitor, reduces the inflammatory reaction in rat experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN) is a T cell-mediated autoimmune inflammatory demyelinating disease of the peripheral nervous system and serves as the animal model of human inflammatory demyelinating polyradiculoneuropathies. MS-275, a potent histone deacetylase inhibitor currently undergoing clinical investigations for various malignancies, has been reported to demonstrate promising anti-inflammatory activities. In our present study, MS-275 administration (3.5 mg/kg i.p.) to EAN rats once daily from the appearance of first neurological signs greatly reduced the severity and duration of EAN and attenuated local accumulation of macrophages, T cells and B cells, and demyelination of sciatic nerves. Further, significant reduction of mRNA levels of pro-inflammatory interleukin-1beta, interferon-gamma, interleukine-17, inducible nitric oxide synthase and matrix metalloproteinase-9 was observed in sciatic nerves of MS-275 treated EAN rats. In lymph nodes, MS-275 depressed pro-inflammatory cytokines as well, but increased expression of anti-inflammatory cytokine interleukine-10 and of foxhead box protein3 (Foxp3), a unique transcription factor of regulatory T cells. In addition, MS-275 treatment increased proportion of infiltrated Foxp3(+) cells and anti-inflammatory M2 macrophages in sciatic nerves of EAN rats. In summary, our data demonstrated that MS-275 could effectively suppress inflammation in EAN, through suppressing inflammatory T cells, macrophages and cytokines, and inducing anti-inflammatory immune cells and molecules, suggesting MS-275 as a potent candidate for treatment of autoimmune neuropathies.

Compound A, a Plant Origin Ligand of Glucocorticoid Receptors, Increases Regulatory T Cells and M2 Macrophages to Attenuate Experimental Autoimmune Neuritis with Reduced Side Effects

Experimental autoimmune neuritis (EAN) is a helper T cell-mediated autoimmune demyelinating inflammatory disease of the peripheral nervous system and serves as the animal model for human inflammatory demyelinating polyneuropathies. Compound A, a plant-derived phenyl aziridine precursor, was reported to activate glucocorticoid receptors to exert transrepression but not transactivation properties. In this study, we investigated the effects of Compound A in EAN rats. Compound A greatly suppressed paraparesis in EAN, even when administrated after the appearance of the first neurological signs. Accumulation of macrophages and lymphocytes, demyelination, and mRNA levels of inflammatory molecules in sciatic nerves of EAN were greatly attenuated by Compound A. In addition, Compound A inhibited progression of neuropathic pain and repressed microglia but not astrocyte activation and IL-1β and TNF-α up-regulation in EAN spinal cords. In EAN sciatic nerves, Compound A treatment increased numbers of anti-inflammatory M2 macrophages. Furthermore, Compound A induced the switch of macrophages from inflammatory M1 type to anti-inflammatory M2 type in vitro. In lymph nodes of EAN rats, Compound A depressed Th1 and Th17 cytokines, but increased Th2 cytokine and Foxp3 expression. An increase of Foxp3+/CD4+ regulatory T cells was seen in peripheral blood of EAN rats following Compound A treatment. In addition, Compound A did not cause a hyperglycemia effect in EAN rats as compared with the immunosuppressive steroid prednisolone. Therefore, our data demonstrated that Compound A could effectively suppress EAN with reduced side effects by attenuating inflammation, suggesting that Compound A could be a potent candidate for treatment of autoimmune neuropathies.