FTY720-induced conversion of conventional Foxp3- CD4+ T cells to Foxp3+ regulatory T cells in NOD mice

Molecular and neuroimmune pharmacology of S1P receptor modulators and other disease-modifying therapies for multiple sclerosis

Multiple sclerosis (MS) is a neurological, immune-mediated demyelinating disease that affects people in the prime of life. Environmental, infectious, and genetic factors have been implicated in its etiology, although a definitive cause has yet to be determined. Nevertheless, multiple disease-modifying therapies (DMTs: including interferons, glatiramer acetate, fumarates, cladribine, teriflunomide, fingolimod, siponimod, ozanimod, ponesimod, and monoclonal antibodies targeting ITGA4, CD20, and CD52) have been developed and approved for the treatment of MS. All the DMTs approved to date target immunomodulation as their mechanism of action (MOA); however, the direct effects of some DMTs on the central nervous system (CNS), particularly sphingosine 1-phosphate (S1P) receptor (S1PR) modulators, implicate a parallel MOA that may also reduce neurodegenerative sequelae. This review summarizes the currently approved DMTs for the treatment of MS and provides details and recent advances in the molecular pharmacology, immunopharmacology, and neuropharmacology of S1PR modulators, with a special focus on the CNS-oriented, astrocyte-centric MOA of fingolimod.

CaMK4 promotes abortion-related Th17 cell imbalance by activating AKT/mTOR signaling pathway

PROBLEM

The balance of the immune microenvironment along the maternal-fetal interface is closely related to pregnancy outcomes, with excessive inflammatory reactions leading to the occurrence of pathological pregnancy outcomes such as abortion. CaMK4 has been reported to play a significant role in autoimmune diseases through the regulation of Th17 cells. However, whether CaMK4 is associated with spontaneous abortion or the immune microenvironment along the maternal-fetal interface remains unclear.

METHODS OF STUDY

In this study, we constructed normal pregnancy and LPS-induced abortion models in mice, and a CaMK4 inhibitor called KN-93 was administered to investigate the changes in and mechanisms of the immune response. The expression of CaMK4 was evaluated in the uteroplacental complex and spleen. Furthermore, the infiltration and function of Th17 cells were estimated in peripheral tissues and the uteroplacental complex.

RESULTS

The expression of CaMK4 in the uteroplacental complex and spleen was significantly higher in the LPS-treated group than in the normal pregnancy group. KN-93, the CaMK4 inhibitor, reversed fetal resorption and excessive inflammation. In detail, KN-93 led to reduced infiltration of Th17 cells into peripheral tissues and the uteroplacental complex, and the functions of Th17 cells were inhibited. In addition, CaMK4 promoted the AKT/mTOR signaling pathway, which is one of the mechanisms that regulate the immune microenvironment.

CONCLUSION

CaMK4 is a critical regulator that promotes the expansion of Th17 cells and enhances their functions through the AKT/mTOR signaling pathway. The inhibition of CaMK4 can reverse the immune imbalance along the maternal-fetal interface and improve pregnancy outcomes.

Fingolimod Increases Brain-Derived Neurotrophic Factor Level Secretion from Circulating T Cells of Patients with Multiple Sclerosis

BACKGROUND

The pathophysiology of multiple sclerosis involves an autoimmune and a neurodegenerative mechanism. Central nervous system-infiltrating immune cells in multiple sclerosis also possess a neuroprotective activity through secretion of neurotrophins, such as brain-derived neurotrophic factor. Fingolimod was shown to slow the progression of disability and loss of brain volume.

OBJECTIVE

The objective of this study was to explore whether fingolimod induces secretion of neurotrophins by immune cells.

METHODS

Blood was drawn from 21 patients before the initiation of treatment with fingolimod and at 6 and 12 months of follow-up. The levels of the neurotrophic factors brain-derived neurotrophic factor, glial cell-derived neurotrophic factor, β-nerve growth factor, neurotrophin-3, neurotrophin-4, basic fibroblast growth factor, epidermal growth factor, and vascular endothelial growth factor were screened in the supernatants of separated T cells and monocyte cultures using a customized, multiplex enzyme-linked immunosorbent assay. Brain-derived neurotrophic factor levels were further validated by a specific enzyme-linked immunosorbent assay.

RESULTS

Treatment with fingolimod significantly increased brain-derived neurotrophic factor secretion from T cells. A specific enzyme-linked immunosorbent assay confirmed these results in the supernatant of T cells after 6 and 12 months of therapy.

CONCLUSIONS

T cells that reach the bloodstream of fingolimod-treated patients with multiple sclerosis may contribute to the neuroprotective effect of this therapy by increased secretion of brain-derived neurotrophic factor. This mechanism of action of fingolimod in patients with multiple sclerosis has not been previously reported.

New extracellular factors in glioblastoma multiforme development: neurotensin, growth differentiation factor-15, sphingosine-1-phosphate and cytomegalovirus infection

Recent years have seen considerable progress in understanding the biochemistry of cancer. For example, more significance is now assigned to the tumor microenvironment, especially with regard to intercellular signaling in the tumor niche which depends on many factors secreted by tumor cells. In addition, great progress has been made in understanding the influence of factors such as neurotensin, growth differentiation factor-15 (GDF-15), sphingosine-1-phosphate (S1P), and infection with cytomegalovirus (CMV) on the 'hallmarks of cancer' in glioblastoma multiforme. Therefore, in the present work we describe the influence of these factors on the proliferation and apoptosis of neoplastic cells, cancer stem cells, angiogenesis, migration and invasion, and cancer immune evasion in a glioblastoma multiforme tumor. In particular, we discuss the effect of neurotensin, GDF-15, S1P (including the drug FTY720), and infection with CMV on tumor-associated macrophages (TAM), microglial cells, neutrophil and regulatory T cells (T_reg), on the tumor microenvironment. In order to better understand the role of the aforementioned factors in tumoral processes, we outline the latest models of intratumoral heterogeneity in glioblastoma multiforme. Based on the most recent reports, we discuss the problems of multi-drug therapy in treating glioblastoma multiforme.

CpG Oligodeoxynucleotides Downregulate Placental Adiponectin and Increase Embryo Loss in Non-Obese Diabetic Mice

PROBLEM

CpG oligodeoxynucleotides (ODNs) can induce immunological changes in non-obese diabetic (NOD) mice and increase embryo loss, but little is known about the mechanism. This study aimed to determine the role of adiponectin in CpG ODN-induced pregnancy failure.

METHOD OF STUDY

Oligodeoxynucleotide 1826 was intraperitoneally injected to NOD mice, and ODN 2216, ODN 2006, and ODN 2395 were used to stimulate human trophoblast cell lines to investigate adiponectin expression patterns and its possible effects on trophoblast function.

RESULTS

CpG ODNs downregulated adiponectin via the cJun N-terminal kinase signaling pathway and led to increased embryo loss (from 6.9 to 33.3%). ODN 2006 impaired human trophoblast cell migration, which was successfully rescued by adiponectin treatment.

CONCLUSION

CpG ODNs decreased placental adiponectin expression in NOD mice and impaired human trophoblast function and was associated with increased embryo loss. Adiponectin may therefore play an important protective role in the prevention of bacteria-induced pregnancy failure.

Baseline Differences in Minor Lymphocyte Subpopulations may Predict Response to Fingolimod in Relapsing-Remitting Multiple Sclerosis Patients

AIMS

Fingolimod, oral treatment for relapsing-remitting multiple sclerosis (RRMS), is an agonist of sphingosine and its metabolite S1P that binds their receptors, blocking the egress of lymphocytes from lymph nodes. The aim of this study was immunomonitoring of minor peripheral lymphocyte subpopulations in RRMS patients under treatment with fingolimod and correlation with treatment response.

METHODS

Prospective study. T- and B-cell subpopulations were analyzed using multiparametric flow cytometry in peripheral blood from 14 RRMS patients under treatment with fingolimod at baseline, +1, +3, +6, +9, and +12 months of follow-up. Response to therapy was assessed at month +12.

RESULTS

Most changes in minor lymphocyte subpopulations occurred in the first month of treatment and were maintained until the end of follow-up. The basal percentages of recent thymic emigrants (RTEs) and transitional B cells were lower in responder patients than in nonresponders. After 1 month of follow-up, the percentages of late effector memory CD4(+) T cells in peripheral blood were higher in responder patients.

CONCLUSION

If confirmed in a bigger cohort of patients, analysis of percentages of minor lymphocyte subpopulations in peripheral blood of patients with RRMS prior and after +1 month of treatment might predict clinical response to fingolimod.

Fingolimod does not impair T-cell release from the thymus and beneficially affects Treg function in patients with multiple sclerosis

Background:

In multiple sclerosis (MS), disturbed T-cell homeostasis affects both conventional CD4+ T cells (Tcon) and regulatory T cells (Treg). Functionally, this is linked to a loss of Treg-suppressive properties. Concerns exist as to whether fingolimod might further aggravate Treg dysfunction by inhibiting thymic egress and, thus, promoting premature immunosenescence.

Objective:

The objective of this paper is to investigate whether fingolimod, by sequestration of developing cells in the thymus, might deteriorate numeric and/or functional disequilibrium of T-cell subtypes.

Methods:

We assessed numbers and phenotypes of blood Tcon and Treg in 74 MS patients treated with fingolimod and in 37 healthy donors. Treg and Tcon were also analyzed for immunoreactivity, suppressive function, sphingosine-1-phosphate-triggered (S1P) trafficking, and S1P-receptor expression. This was complemented by assessing surrogate markers of thymic T-cell development, including frequencies of cells expressing T-cell receptors (TCR) of dual specificity, and TCR diversity in Treg.

Results:

Fingolimod did not negatively affect naive T-cell phenotypes or markers of thymic T-cell development. By reducing CCR7-expressing Tcon, fingolimod increased relative proportions of Treg. As a result of this shift, fewer proliferative CCR7− Tcon became enriched and Treg-dysfunction was indirectly reversed.

Conclusion:

These observations argue against harmful interference of fingolimod with thymic T-cell output that, particularly in pediatric MS, might possibly counteract its beneficial effects.

Fingolimod increases CD39-expressing regulatory T cells in multiple sclerosis patients

Background

Multiple sclerosis (MS) likely results from an imbalance between regulatory and inflammatory immune processes. CD39 is an ectoenzyme that cleaves ATP to AMP and has been suggested as a novel regulatory T cells (Treg) marker. As ATP has numerous proinflammatory effects, its degradation by CD39 has anti-inflammatory influence. The purpose of this study was to explore regulatory and inflammatory mechanisms activated in fingolimod treated MS patients.

Methods and Findings

Peripheral blood mononuclear cells (PBMCs) were isolated from relapsing-remitting MS patients before starting fingolimod and three months after therapy start. mRNA expression was assessed in ex vivo PBMCs. The proportions of CD8, B cells, CD4 and CD39-expressing cells were analysed by flow cytometry. Treg proportion was quantified by flow cytometry and methylation-specific qPCR. Fingolimod treatment increased mRNA levels of CD39, AHR and CYP1B1 but decreased mRNA expression of IL-17, IL-22 and FOXP3 mRNA in PBMCs. B cells, CD4⁺ cells and Treg proportions were significantly reduced by this treatment, but remaining CD4⁺ T cells were enriched in FOXP3⁺ cells and in CD39-expressing Tregs.

Conclusions

In addition to the decrease in circulating CD4⁺ T cells and CD19⁺ B cells, our findings highlight additional immunoregulatory mechanisms induced by fingolimod.

Fingolimod attenuates splenocyte-induced demyelination in cerebellar slice cultures

The family of sphingosine-1-phosphate receptors (S1PRs) is G-protein-coupled, comprised of subtypes S1PR1-S1PR5 and activated by the endogenous ligand S1P. The phosphorylated version of Fingolimod (pFTY720), an oral therapy for multiple sclerosis (MS), induces S1PR1 internalisation in T cells, subsequent insensitivity to S1P gradients and sequestering of these cells within lymphoid organs, thus limiting immune response. S1PRs are also expressed in neuronal and glial cells where pFTY720 is suggested to directly protect against lysolecithin-induced deficits in myelination state in organotypic cerebellar slices. Of note, the effect of pFTY720 on immune cells already migrated into the CNS, prior to treatment, has not been well established. We have previously found that organotypic slice cultures do contain immune cells, which, in principle, could also be regulated by pFTY720 to maintain levels of myelin. Here, a mouse organotypic cerebellar slice and splenocyte co-culture model was thus used to investigate the effects of pFTY720 on splenocyte-induced demyelination. Spleen cells isolated from myelin oligodendrocyte glycoprotein immunised mice (MOG-splenocytes) or from 2D2 transgenic mice (2D2-splenocytes) both induced demyelination when co-cultured with mouse organotypic cerebellar slices, to a similar extent as lysolecithin. As expected, in vivo treatment of MOG-immunised mice with FTY720 inhibited demyelination induced by MOG-splenocytes. Importantly, in vitro treatment of MOG- and 2D2-splenocytes with pFTY720 also attenuated demyelination caused by these cells. In addition, while in vitro treatment of 2D2-splenocytes with pFTY720 did not alter cell phenotype, pFTY720 inhibited the release of the pro-inflammatory cytokines such as interferon gamma (IFNγ) and interleukin 6 (IL6) from these cells. This work suggests that treatment of splenocytes by pFTY720 attenuates demyelination and reduces pro-inflammatory cytokine release, which likely contributes to enhanced myelination state induced by pFTY720 in organotypic cerebellar slices.

Molecular pharmacodynamics of new oral drugs used in the treatment of multiple sclerosis

New oral drugs have considerably enriched the therapeutic armamentarium for the treatment of multiple sclerosis. This review focuses on the molecular pharmacodynamics of fingolimod, dimethyl fumarate (BG-12), laquinimod, and teriflunomide. We specifically comment on the action of these drugs at three levels: 1) the regulation of the immune system; 2) the permeability of the blood-brain barrier; and 3) the central nervous system. Fingolimod phosphate (the active metabolite of fingolimod) has a unique mechanism of action and represents the first ligand of G-protein-coupled receptors (sphingosine-1-phosphate receptors) active in the treatment of multiple sclerosis. Dimethyl fumarate activates the nuclear factor (erythroid-derived 2)-related factor 2 pathway of cell defense as a result of an initial depletion of reduced glutathione. We discuss how this mechanism lies on the border between cell protection and toxicity. Laquinimod has multiple (but less defined) mechanisms of action, which make the drug slightly more effective on disability progression than on annualized relapse rate in clinical studies. Teriflunomide acts as a specific inhibitor of the de novo pyrimidine biosynthesis. We also discuss new unexpected mechanisms of these drugs, such as the induction of brain-derived neurotrophic factor by fingolimod and the possibility that laquinimod and teriflunomide regulate the kynurenine pathway of tryptophan metabolism.

Prevention of CpG-induced pregnancy disruption by adoptive transfer of in vitro-induced regulatory T cells

OBJECTIVE

To elucidate the mechanism by which embryo-resorption and preterm birth were enhanced by pathogenic CpG motif and to develop a counter strategy for normal pregnancy outcome.

METHODS

This is an animal model-based study. In pregnant nonobese diabetic (NOD) mice and wild-type (WT) mice in the same strain background, an infection was mimicked by toll-like receptor 9 (TLR9) activation through CpG1826-injection. In vivo inactivation of IL-10 was performed to enhance pregnancy loss. Regulatory T cells induced by FTY720 in vitro from splenic CD4+CD25-Foxp3- cells (iTreg cells) were transferred to improve pregnancy outcomes in NOD mice.

RESULTS

Embryo-resorption and preterm birth were readily induced by CpG1826 in NOD mice, but not in WT mice. However, inactivation of IL-10 using neutralizing antibody injections enhanced pregnancy loss in WT mice exposed to CpG, while adoptive transfer of iTreg cells increased decidual Foxp3+ Treg cells and IL-10+ cell number and rescued pregnancy.

CONCLUSIONS

NOD mice are prone to abortion and preterm birth. This can be attributed to lacking Treg cells and insufficient IL-10 expression. Adoptive transfer of iTreg cells can rescue CpG-mediated pregnancy failure.

Emerging roles for lysophospholipid mediators in pregnancy

Recent progress in lipid research has unveiled new biologic roles for lysophospholipids as mediators of intercellular signaling. Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are representative lysophospholipids. Accumulating evidence suggests that, acting as intercellular mediators, these and other lysophospholipids may play important roles in physiological and pathological situations. This review discusses the possible involvement of LPA and S1P in reproductive processes, with a focus on the regulatory mechanisms of pregnancy maintenance. As LPA promotes prostaglandin synthesis, mediators in the LPA pathway may also play a significant role in implantation and parturition. S1P signaling is thought to be essential in vascular formation within the uteroplacental unit and in fetomaternal immunologic interactions. Derangements in either one of these lysophospholipid signaling pathways could result in pregnancy complications that may include implantation failure, preeclampsia, and preterm labor.

Systemic lupus erythematosus: a therapeutic challenge for the XXI century

Despite significant advances in our understanding of the pathogenesis of systemic lupus erythematosus (SLE), there are only a few drugs approved by the regulatory agencies across the world for the treatment of these patients; in fact, many of the compounds subjected to clinical trials have failed in achieving their primary endpoints. Current therapeutic options include antimalarials which should be used in all SLE patients unless they are strongly contraindicated, glucocorticoids which should be used at the lowest possible dose and for the shortest possible time, and immunosuppressive drugs which should be used judiciously, mainly in patients with severe organ involvements or receiving high doses of steroids to control their disease. Despite improvement on the survival of SLE patients, damage accrual has not varied over the last few decades, reflecting a gap between these therapeutic options and the expectations of these patients and their treating physicians. Biologic compounds can be used in some refractory cases. However, their cost is of great concern for both the patients and the health system. Cost is of special importance in low-income countries, because low-income SLE patients tend to experience a more severe disease having an overall worse prognosis which is compounded by their limited access to the health system. Although a treatment to target based on defined molecular pathways for specific disease subsets is appealing, this is not yet a reality. This review addressed current therapeutic options for SLE patients and the state of the art of investigational drugs targeting pathogenic pathways identified in these patients.

Novel sphingosine-1-phosphate receptor modulator KRP203 combined with locally delivered regulatory T cells induces permanent acceptance of pancreatic islet allografts

BACKGROUND

KRP203, a structural FTY720 analogue, has 5-fold greater selectivity for binding to sphingosine-1-phosphate receptor (S1PR) 1 (S1PR(1)) versus S1PR3 and 100-fold greater selectivity over S1PR(2) and S1PR(5). Although the immunoregulatory effects of FTY720 have been tested in clinical and experimental research, the therapeutic efficacy of KRP203 in allograft models remains elusive. In this study, we investigated the potential of KRP203 alone and in combination with intragraft injection of CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) to induce islet allograft tolerance.

METHODS

BALB/c (H-2(d)) mice received transplants of fresh C57BL/10 (H-2(b)) islet allografts under the kidney capsule and were treated for 7 days with 0.3, 1.0, or 3.0 mg/kg KRP203 alone or in combination with intragraft-infused Tregs.

RESULTS

Untreated BALB/c mice acutely rejected C57BL/10 islet allografts at a mean survival time of 13.8 ± 2.7 days (n=5). A 7-day dosing of 0.3 or 1.0 mg/kg KRP203 produced long-term islet allograft survival (9200 days) in one of five and two of seven recipients, respectively. A 3 mg/kg KRP203 dose resulted in islet graft survival for more than 200 days in 5 of 12 recipients. Whereas recipients that received 500 allogeneic islets admixed with 5 x 10(5) - 7 x 10(5) Tregssurvived 83.6 ± 67.2 days, addition of transient 3 mg/kg KRP203 therapy induced prolonged drug-free graft survival (9200 days) in all recipients.

CONCLUSIONS

A brief treatment with KRP203 significantly prolonged islet allograft survival, whereas additional intragraft delivery of Tregs induced tolerogenic effects selective to islet alloantigens.

Oral FTY720 administration induces immune tolerance and inhibits early development of atherosclerosis in apolipoprotein E-deficient mice

Orally administered immunomodulatory drugs have recently demonstrated the ability to induce an oral tolerance via inhibition of effector T cells and induction of certain subsets of regulatory T cells (Tregs) which have the potential to prevent several autoimmune diseases. In the present study, we hypothesized that short-term, low-dose, oral FTY720 administration may induce latency-associated peptide (LAP) Tregs and CD4(+) Foxp3(+) Tregs in atherogenesis, potentially resulting in remission of early development of atherosclerosis in apolipoprotein E-deficient (APOE(-/-)) mice. FTY720 was orally administered to APOE(-/-) mice 4 weeks of age on a high-cholesterol diet and atherosclerosis was assessed at 8 weeks of age. Oral administration of FTY720 significantly reduced atherosclerotic lesion formation compared with control mice. We observed a significant increase in LAP(+) and Foxp3(+) cells in the CD4+T-cell population of FTY720-treated mice in association with increased production of the anti-inflammatory cytokine transforming growth factor-β (TGF-β) as well as suppressed T-helper type 1 immune responses. Our findings reveal that short-term, low-dose oral FTY720 treatment had great benefits in inhibiting early development of atherosclerosis in mice via induction of a regulatory T-cell response and inhibition of effector T responses. These findings suggest that oral immune modulation may represent an attractive therapeutic approach to atherosclerosis.