Peripheral blood T cell dynamics predict relapse in multiple sclerosis patients on fingolimod

Response to Fingolimod in Multiple Sclerosis Patients Is Associated with a Differential Transcriptomic Regulation

Fingolimod is an immunomodulatory sphingosine-1-phosphate (S1P) analogue approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). The identification of biomarkers of clinical responses to fingolimod is a major necessity in MS to identify optimal responders and avoid the risk of disease progression in non-responders. With this aim, we used RNA sequencing to study the transcriptomic changes induced by fingolimod in peripheral blood mononuclear cells of MS-treated patients and their association with clinical response. Samples were obtained from 10 RRMS patients (five responders and five non-responders) at baseline and at 12 months of fingolimod therapy. Fingolimod exerted a vast impact at the transcriptional level, identifying 7155 differentially expressed genes (DEGs) compared to baseline that affected the regulation of numerous signaling pathways. These DEGs were predominantly immune related, including genes associated with S1P metabolism, cytokines, lymphocyte trafficking, master transcription factors of lymphocyte functions and the NF-kB pathway. Responder and non-responder patients exhibited a differential transcriptomic regulation during treatment, with responders presenting a higher number of DEGs (6405) compared to non-responders (2653). The S1P, NF-kB and TCR signaling pathways were differentially modulated in responder and non-responder patients. These transcriptomic differences offer the potential of being exploited as biomarkers of a clinical response to fingolimod.

Enhanced and complementary benefits of a nalfurafine and fingolimod combination to treat immune-driven demyelination

OBJECTIVES

Multiple sclerosis (MS) is a neurodegenerative disease characterised by inflammation and damage to myelin sheaths. While all current disease-modifying treatments (DMTs) are very effective at reducing relapses, they do not slow the progression of the disease, and there is little evidence that these treatments are able to repair or remyelinate damaged axons. Recent evidence suggests that activating kappa opioid receptors (KORs) has a beneficial effect on the progression of MS, and this study investigates the effects of KOR agonists treatment in combination with two current DMTs.

METHODS

Using the well-established murine model for immune-driven demyelination of MS, experimental autoimmune encephalomyelitis, the effect of KOR agonists in combination with DMTs fingolimod or dimethyl fumarate on disease progression, immune cell infiltration and activation as well as myelination were analysed.

RESULTS

Fingolimod in combination with the KOR agonist, nalfurafine, significantly increased each individual beneficial effect as measured by increased recovery of mice and reduced relapses. These beneficial effects correlated with a reduction in immune cell infiltration into the CNS as well as peripheral immune cell alterations including a reduction in autoreactive CD4+ T-cell cytokine production as well as increased myelination in the spinal cords of co-treated animals. In contrast, while the use of dimethyl fumarate in combination with nalfurafine did not adversely affect the benefits of nalfurafine, the combination did not significantly enhance those benefits.

CONCLUSION

This study indicates that KOR agonists can be used in combination with fingolimod and dimethyl fumarate with the nalfurafine-fingolimod combination providing enhanced benefits.

Multiple faces of multiple sclerosis in the era of highly efficient treatment modalities: Lymphopenia and switching treatment options challenges daily practice

The expanded treatment landscape in relapsing-remitting multiple sclerosis (MS) has resulted in highly effective treatment options and complexity in managing disease- or drug-related events during disease progression. Proper decision-making requires thorough knowledge of the immunobiology of MS itself and an understanding of the main principles behind the mechanisms that lead to secondary autoimmunity affecting organs other than the central nervous system as well as opportunistic infections. The immune system is highly adapted to both environmental and disease-modifying agents. Immune reconstitution following cell depletion or cell entrapment therapies eliminates pathogenic aspects of the disease but can also lead to distorted immune responses with harmful effects. Atypical relapses occur with second-line treatments or after their discontinuation and require appropriate clinical decisions. Lymphopenia is a result of the mechanism of action of many drugs used to treat MS. However, persistent lymphopenia and cell-specific lymphopenia could result in disease exacerbation, secondary autoimmunity, or the emergence of opportunistic infections. Clinicians treating patients with MS should be aware of the multiple faces of MS under novel, efficient treatment modalities and understand the intricate brain-immune cell interactions in the context of an altered immune system. MS relapses and disease progression still occur despite the current treatment modalities and are mediated either by failure to control effector mechanisms inherent to MS pathophysiology or by new drug-related mechanisms. The multiple faces of MS due to the highly adapted immune system of patients impose the need for appropriate switching therapies that safeguard disease remission and further clinical improvement.

The impact of fingolimod on Treg function in brain ischaemia

Fingolimod has generally shown neuroprotective effects in stroke models. Here, we tested the hypothesis that fingolimod modulates T-cell cytokine production towards a regulatory phenotype. Second, we investigated how fingolimod altered the Treg suppressive function and the sensitivity of effector T cells to regulation. Mice that had underwent the permanent electrocoagulation of the left middle cerebral artery received saline or fingolimod (0.5 mg/kg) daily for 10-days post-ischaemia. Fingolimod improved neurobehavioural recovery compared to saline control and increased Treg frequency in the periphery and brain. Tregs from fingolimod-treated animals had a higher expression of CCR8. Fingolimod increased the frequencies of CD4+ IL-10+ , CD4+ IFN-γ+ and CD4+ IL-10+ IFN-γ+ cells in spleen and blood, and CD4+ IL-17+ cells in the spleen, with only minor effects on CD8+ T-cell cytokine production. Treg from post-ischaemic mice had reduced suppressive function compared to Treg from non-ischaemic mice. Fingolimod treatment rescued this function against saline-treated but not fingolimod-treated CD4+ effector T cells. In conclusion, fingolimod seems to improve the suppressive function of Treg post-stroke while also increasing the resistance of CD4+ effector cells to this suppression. Fingolimod's capacity to increase both effector and regulatory functions may explain the lack of consistent improvement in functional recovery in experimental brain ischaemia.

[A case of multiple sclerosis with a tumefactive lesion during long-term treatment with fingolimod, leading to decompressive craniotomy]

We report a 57-year-old man with multiple sclerosis since his 30s who was treated with fingolimod for 9 years. He developed left hemiparesis and consciousness disturbance. Brain MRI revealed a mass lesion in the right frontal lobe with gadolinium enhancement. Cerebrospinal fluid examination showed no pleocytosis. The lesion continued to expand after admission, and on the 9th day after admission, decompressive craniectomy and brain biopsy were performed. Brain pathology revealed demyelination in the lesion, leading to the diagnosis of a tumefactive demyelinating lesion. Corticosteroid therapy ameliorated the brain lesion, and we inducted natalizumab. Tumefactive demyelinating lesions requiring decompressive craniotomy are rare, and we report this case for the further accumulation of similar cases.

Immune cell subset profiling in multiple sclerosis after fingolimod initiation and continued treatment: The FLUENT study

Background

Fingolimod is a sphingosine 1-phosphate receptor modulator approved for relapsing MS. Long-term effects on the immunological profile are not fully understood.

Objective

Investigate fingolimod's temporal effects on immune cell subsets, and safety outcomes.

Methods

In FLUENT, a 12-month, prospective, non-randomized, open-label, phase IV study, adult participants received fingolimod 0.5 mg/day. Changes in immune cell subsets, anti-John Cunningham virus (JCV) antibody index, and serum neurofilament levels were assessed.

Results

165 fingolimod-naive and 217 participants treated for 2–12 years in routine clinical practice were enrolled. Levels of all monitored peripheral lymphocyte subsets were reduced from month 3 in fingolimod-naive participants. Greatest reductions occurred in naive and central memory CD4+ and CD8+ T cells, and in naive and memory B cells. Most lymphocyte subset levels remained stable in the continuous fingolimod group. Components of the innate immune system remained within reference ranges. No increase in JCV seropositivity was observed. No single cellular subset correlated with anti-JCV antibody index at any time point. Neurofilament levels remained within healthy adult reference limits throughout. No opportunistic infections were reported; no new or unexpected safety signals were observed.

Conclusion

FLUENT provides insights into the utility of immunological profiling to evaluate therapy response and potential infection risk.

Identification and validation a costimulatory molecule gene signature to predict the prognosis and immunotherapy response for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Costimulatory molecules have been proven to be the foundation of immunotherapy. However, the potential roles of costimulatory molecule genes (CMGs) in HCC remain unclear. Our study is aimed to develop a costimulatory molecule-related gene signature that could evaluate the prognosis of HCC patients.

METHODS

Based on The Cancer Gene Atlas (TCGA) database, univariate Cox regression analysis was applied in CMGs to identify prognosis-related CMGs. Consensus clustering analysis was performed to stratify HCC patients into different subtypes and compared them in OS. Subsequently, the LASSO Cox regression analysis was performed to construct the CMGs-related prognostic signature and Kaplan-Meier survival curves as well as ROC curve were used to validate the predictive capability. Then we explored the correlations of the risk signature with tumor-infiltrating immune cells, tumor mutation burden (TMB) and response to immunotherapy. The expression levels of prognosis-related CMGs were validated based on qRT-PCR and Human Protein Atlas (HPA) databases.

RESULTS

All HCC patients were classified into two clusters based on 11 CMGs with prognosis values and cluster 2 correlated with a poorer prognosis. Next, a prognostic signature of six CMGs was constructed, which was an independent risk factor for HCC patients. Patients with low-risk score were associated with better prognosis. The correlation analysis showed that the risk signature could predict the infiltration of immune cells and immune status of the immune microenvironment in HCC. The qRT-PCR and immunohistochemical results indicated six CMGs with differential expression in HCC tissues and normal tissues.

CONCLUSION

In conclusion, our CMGs-related risk signature could be used as a prediction tool in survival assessment and immunotherapy for HCC patients.

The Two Sides of Siponimod: Evidence for Brain and Immune Mechanisms in Multiple Sclerosis

Siponimod is a selective sphingosine 1-phosphate receptor subtype 1 (S1P₁) and 5 (S1P₅) modulator approved in the United States and the European Union as an oral treatment for adults with relapsing forms of multiple sclerosis (RMS), including active secondary progressive multiple sclerosis (SPMS). Preclinical and clinical studies provide support for a dual mechanism of action of siponimod, targeting peripherally mediated inflammation and exerting direct central effects. As an S1P₁ receptor modulator, siponimod reduces lymphocyte egress from lymph nodes, thus inhibiting their migration from the periphery to the central nervous system. As a result of its peripheral immunomodulatory effects, siponimod reduces both magnetic resonance imaging (MRI) lesion (gadolinium-enhancing and new/enlarging T2 hyperintense) and relapse activity compared with placebo. Independent of these effects, siponimod can penetrate the blood-brain barrier and, by binding to S1P₁ and S1P₅ receptors on a variety of brain cells, including astrocytes, oligodendrocytes, neurons, and microglia, exert effects to modulate neural inflammation and neurodegeneration. Clinical data in patients with SPMS have shown that, compared with placebo, siponimod treatment is associated with reductions in levels of neurofilament light chain (a marker of neuroaxonal damage) and thalamic and cortical gray matter atrophy, with smaller reductions in MRI magnetization transfer ratio and reduced confirmed disability progression. This review examines the preclinical and clinical data supporting the dual mechanism of action of siponimod in RMS.

The Association of EBV and HHV-6 Viral Load with Different NK and CD8+ T Cell Subsets in The Acute Phase of Relapsing-Remitting Multiple Sclerosis

OBJECTIVE

Epstein-Barr virus (EBV) and Human Herpes virus 6 (HHV-6) are believed to involve in multiple sclerosis (MS) pathogenesis. Natural killer (NK) and CD8+ T cells have essential roles in handling viral infections and their phenotypic and functional properties may be influenced following exposure to viral infections. Here, we investigated the association of NK and CD8+ T cells subpopulations frequency with EBV and HHV-6 viral load in MS patients.

MATERIALS AND METHODS

In this case-control study, EBV and HHV-6 viral load were evaluated in plasma of newly diagnosed relapsing-remitting MS (RRMS) patients at relapse phase (n=23), who were not on disease-modifying therapy (DMT), and sex- and age-matched healthy controls (n=19) using real-time polymerase chain reaction (PCR). The frequency of NK and CD8+ T cells subsets were assessed by CD27, CD28, CD45RO, CD56, and CD57 markers using flow cytometry.

RESULTS

Despite the increased level of EBV viral load in RRMS patients compared to the control group, there was no statistically significant difference in EBV and HHV-6 copy numbers between the studied groups. In addition, a significant decrease was observed in the percentages of CD56bright CD57- and CD56dim CD57+ CD8low CD45RO- NK cells in RRMS patients in comparison to healthy controls. Analysis of CD8+ T cell subsets showed a substantially high proportion of CD27+ CD28+ CD45RO+ CD57- CD8hi T cells in patients at relapse phase compared to controls. The frequency of NK and T cells subtypes was not associated with EBV and HHV6 plasma viral loads.

CONCLUSION

These findings further highlight the variation of NK and CD8+ T cells subsets frequency in clinically active RRMS patients. Since the composition of cells was not associated with EBV and HHV-6 viral load, perhaps other viral infections may be involved in altered NK and CD8+ T cells subpopulation. Larger cohort studies are needed to confirm these results.

Drug-related demyelinating syndromes: understanding risk factors, pathophysiological mechanisms and magnetic resonance imaging findings

Some drugs and medications can precipitate immune system deregulations, which might be confused with recurrent demyelinating diseases, such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMO), exacerbations of an existing disease, neoplastic lesions or other conditions. In this narrative review we describe some of the most relevant drugs and medications associated with iatrogenic demyelination. The anthelminthic agent levamisole is a frequent cocaine adulterant and can precipitate an exacerbated immune response attacking the central nervous system (CNS). High-efficacy multiple sclerosis (MS) drugs might induce a selective CNS immunosuppression, making it susceptible for opportunistic infections that course with demyelination, such as progressive multifocal leukoencephalopathy. Sometimes, the interruption of a high-efficacy drug to treat MS can induce a rapid CNS reentry of lymphocytes, exacerbating demyelinating processes and triggering rebound syndromes. Furthermore, selective cytokines inhibition, such as anti-TNFα agents, might induce an imbalance between cell death and proliferation inducing a paradoxical increase of CNS tumor necrosis factor (TNF), affecting the activity of lymphocytes, microglia and macrophages, triggering aberrant inflammation and demyelination. Immune checkpoint inhibitors are a new class of antineoplastic drugs that enhance the immune response against tumor cells by an upregulation of T-cell activity. However, this hyperactivation of the immune system might be associated with induction of unwanted autoimmune responses. In this paper we review the risk factors, the possible pathological mechanisms and the magnetic resonance imaging (MRI) findings of these drug-related demyelinating syndromes.

An Overview of the Efficacy and Safety of Ozanimod for the Treatment of Relapsing Multiple Sclerosis

Multiple sclerosis (MS) is a complex disease of the central nervous system that can cause permanent disability in young adults. A large armamentarium is available for its management and is increasing over time. Ozanimod is an oral drug belonging to the sphingosine-1-phosphate receptor (S1PR) modulator family recently approved in different countries for MS with active disease. It selectively modulates S1PR1 and S1PR5 to prevent autoreactive lymphocytes from entering the central nervous system (CNS), where they can determine inflammation and neurodegeneration. Ozanimod was tested in one Phase II and two Phase III pivotal trials and was shown to be effective and well tolerated. Moreover, further investigations, including comparative trials with other S1P modulators and MS disease-modifying drugs, are needed to better define placement in MS treatment. Furthermore, ozanimod is currently under evaluation for inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease, in international phase III studies. This article retraces the itinerary leading to the approval of ozanimod for MS treatment and its peculiarities and potentiality inside the S1PR modulator family.

Challenges of switching towards anti-CD20 monoclonal antibodies in RR-MS: A monocentric study

BACKGROUND

Anti-CD20 monoclonal antibodies (mAb) have demonstrated their drastic efficacy in the treatment of active relapsing-remitting multiple sclerosis (RR-MS). This study investigates the management of their initiation after another disease modifying therapy (DMT). The objective of this study was to assess the frequency and the risk factors of relapses during the wash-out period (WP) between cessation of last DMT and initiation of anti-CD20 mAb in RR-MS.

METHODS

All non-naive RR-MS patients who initiated a treatment with Rituximab or Ocrelizumab between 2016 and 2019 have been included in this retrospective monocentric study. Univariate and multivariate analysis were conducted to evaluate risk factors of relapses during the WP.

RESULTS

73 patients (mean age 35.3 years, standard deviation (SD): 8.7 years) were included, with a mean number of 3.1 (SD: 1.3) previous DMTs. The DMT most frequently received before the switch was Fingolimod (Fg, 31 patients, 42.5%). 20 patients (27.4%) experienced relapses during the WP. Risk factors were previous treatment by Fg (p = 0.001) and WP duration (p = 0.032). Among patients switching from Fg, the probability of experiencing a relapse was 35% after 1 month of wash-out.

CONCLUSION

This study suggests to shorten the WP duration when switching towards anti-CD20 mAb, especially after Fg, to avoid relapses.

Switch from sequestering to anti-CD20 depleting treatment: disease activity outcomes during wash-out and in the first 6 months of ocrelizumab therapy

OBJECTIVES

Switching between treatments is an opportunity for patients with multiple sclerosis (MS) to ameliorate disease control or safety. The aim of this study was to investigate the impact of switching from fingolimod (FTY) or natalizumab (NTZ) to ocrelizumab (OCR) on disease activity.

METHODS

We retrospectively enrolled 165 patients treated with OCR from 11 MS centres. We assessed the association of demographic and clinical characteristics on relapse rate (RR) and activity on magnetic resonance imaging (MRI) during wash-out and after 6 months of treatment with OCR through univariable and multivariable negative binomial regression models.

RESULTS

We registered a total of 35 relapses during the wash-out period. Previous treatment with FTY, relapses in the previous year, and relapsing-remitting course were associated with higher RR. In the first 6 months of OCR, 12 patients had clinical or MRI disease activity. Higher Expanded Disability Status Scale (EDSS) and higher lymphocyte count at OCR start were associated with a reduced probability of relapse.

DISCUSSION AND CONCLUSION

This study confirms that withdrawal from sequestering agents as FTY increases the risk of relapses in the wash-out period. Nevertheless, starting OCR before achieving complete immune reconstitution could limit its effectiveness in the first 6 months probably because trapped lymphocytes escape the CD20-mediated depletion.

A mathematical model of the multiple sclerosis plaque

Multiple sclerosis is an autoimmune disease that affects white matter in the central nervous system. It is one of the primary causes of neurological disability among young people. Its characteristic pathological lesion is called a plaque, a zone of inflammatory activity and tissue destruction that expands radially outward by destroying the myelin and oligodendrocytes of white matter. The present paper develops a mathematical model of the multiple sclerosis plaques. Although these plaques do not provide reliable information of the clinical disability in MS, they are nevertheless useful as a primary outcome measure of Phase II trials. The model consists of a system of partial differential equations in a simplified geometry of the lesion, consisting of three domains: perivascular space, demyelinated plaque, and white matter. The model describes the activity of various pro- and anti-inflammatory cells and cytokines in the plaque, and quantifies their effect on plaque growth. We show that volume growth of plaques are in qualitative agreement with reported clinical studies of several currently used drugs. We then use the model to explore treatments with combinations of such drugs, and with experimental drugs. We finally consider the benefits of early vs. delayed treatment.

Treatment effects of fingolimod in multiple sclerosis: Selective changes in peripheral blood lymphocyte subsets

BACKGROUND

Treatment with fingolimod reduces inflammation in multiple sclerosis (MS) by inhibiting lymphocyte egress from lymph nodes. We aimed to map, in detail, the alterations in peripheral blood lymphocyte subpopulations in relation to clinical outcome in MS patients treated with fingolimod.

METHODS

Paired blood samples from relapsing-remitting MS patients (n = 19) were collected before and after one year of treatment with fingolimod (0.5 mg/day). Absolute counts and relative proportions of a broad set of T- B- and NK-cell subsets were analyzed by flow cytometry. Blood samples from 18 healthy controls were used for baseline comparisons.

RESULTS

Treatment with fingolimod markedly decreased the absolute numbers of all major lymphocyte subsets, except for NK cells. The reduction was most pronounced within the T helper (Th) and B cell populations (p<0.001). By phenotyping differentiation status of T cells, dramatic reductions within the naïve and central memory (CM) cell populations were found (p<0.001), while a less pronounced reduction was observed among effector memory (EM) cells (p<0.001). The numbers of regulatory T cells (Tregs) were also decreased (p<0.001), but to a lesser extent than other T cell populations, resulting in a relative preservation of Tregs with a memory phenotype (p = 0.002).

CONCLUSIONS

Our results confirm that fingolimod therapy markedly reduces lymphocyte counts in peripheral blood of MS patients. Subgroup analysis of T cells showed that naïve and CM Th cells were the most profoundly affected and that memory Tregs were relatively preserved.

Pre-treatment T-cell subsets associate with fingolimod treatment responsiveness in multiple sclerosis

Biomarkers predicting fingolimod (FTY) treatment response in relapsing-remitting multiple sclerosis (RRMS) are lacking. Here, we performed extensive functional immunophenotyping using multiparametric flow cytometry to examine peripheral immune changes under FTY treatment and explore biomarkers of FTY treatment response. From among 135 RRMS patients who initiated FTY in a 2-year multicentre observational study, 36 were classified as ‘Active’ or ‘Stable’ based on clinical and/or radiological activity on-treatment. Flow cytometric analysis of immune cell subsets was performed on pre- and on-treatment peripheral blood mononuclear cells (PBMC) samples. Decreased absolute counts of B cells and most T-cell subsets were seen on-treatment. Senescent CD8 + T cells, CD56 + T cells, CD56^dim natural killer cells, monocytes and dendritic cells were not reduced in number and hence relatively increased in frequency on-treatment. An unbiased multiparametric and traditional manual analysis of T-cell subsets suggested a higher pre-treatment frequency of CD4 + central memory T cells (TCM) in patients who were subsequently Active versus Stable on-treatment. Lower pre-treatment terminally differentiated effector memory (TEMRA) cell frequencies were also seen in the subsequently Active cohort. Together, our data highlight differential effects of FTY on peripheral immune cell subsets and suggest that pre-treatment T-cell subset frequencies may have value in predicting FTY treatment response.

The FLUENT study design: investigating immune cell subset and neurofilament changes in patients with relapsing multiple sclerosis treated with fingolimod

Background

Fingolimod is a sphingosine 1-phosphate receptor modulator for the treatment of patients with relapsing forms of multiple sclerosis (RMS). Fingolimod sequesters lymphocytes within lymphoid tissue thereby reducing the counts of circulating lymphocytes. However, fingolimod's effects on the innate and adaptive components of the immune system are incompletely understood.

Objective

The FLUENT study will investigate temporal changes in circulating immune cell subsets in patients with RMS treated with fingolimod. Secondary objectives include examining the association between anti-John Cunningham virus (JCV) antibody status/index and phenotypic changes in innate and T and B cell subsets in patients on fingolimod therapy, and the association between serum neurofilament levels and clinical outcomes.

Methods

FLUENT is a prospective, multicenter, two-cohort, nonrandomized, open-label Phase IV study. Cohort 1 will include fingolimod-naïve patients and Cohort 2 will include patients who have received fingolimod 0.5 mg/day continuously for ≥2 years. Changes in the cellular components of the innate and adaptive immune system will be characterized over 12 months.

Results

The study is ongoing.

Conclusion

FLUENT may provide evidence for the use of immunologic profiling in predicting efficacy and risk of infection in patients with RMS treated with fingolimod.

Ozanimod for the treatment of relapsing remitting multiple sclerosis

INTRODUCTION

Ozanimod is a selective sphingosine 1-phosphate receptor 1 and 5 modulator under development by Celgene, for the treatment of relapsing remitting multiple sclerosis. Extensive clinical experience has become available for the related compound fingolimod, favoring the sphingosine 1-phosphate therapeutic concept. Off-target effects have been attributed to its low receptor specificity and have prompted the development of next generation sphingosine 1-phosphate receptor modulators. Areas covered: The authors evaluate the literature of ozanimod, using the PubMed database as well as repositories of the European Committee for Treatment and Research in Multiple Sclerosis and the American and European Academy of Neurology. Specifically, the authors cover and discuss the preclinical data on ozanimod, pharmacokinetics and dynamics, and data on efficacy and safety from the pivotal trials. Expert opinion: Superiority of ozanimod over intramuscular interferon β-1a with regard to reduction in annualized relapse rate and magnetic resonance imaging outcomes has been shown in two phase III trials. The beneficial effect on brain volume and gray matter loss are encouraging and in line with data on other newer immunomodulators. Ozanimod is a valuable contribution to the therapeutic armamentarium in MS, although the effect on disability progression is unclear and requires further investigations.

Experimental Autoimmune Encephalomyelitis (EAE) as Animal Models of Multiple Sclerosis (MS)

Multiple sclerosis (MS) is a multifocal demyelinating disease of the central nervous system (CNS) leading to the progressive destruction of the myelin sheath surrounding axons. It can present with variable clinical and pathological manifestations, which might reflect the involvement of distinct pathogenic processes. Although the mechanisms leading to the development of the disease are not fully understood, numerous evidences indicate that MS is an autoimmune disease, the initiation and progression of which are dependent on an autoimmune response against myelin antigens. In addition, genetic susceptibility and environmental triggers likely contribute to the initiation of the disease. At this time, there is no cure for MS, but several disease-modifying therapies (DMTs) are available to control and slow down disease progression. A good number of these DMTs were identified and tested using animal models of MS referred to as experimental autoimmune encephalomyelitis (EAE). In this review, we will recapitulate the characteristics of EAE models and discuss how they help shed light on MS pathogenesis and help test new treatments for MS patients.

Immune Cell Profiling During Switching from Natalizumab to Fingolimod Reveals Differential Effects on Systemic Immune-Regulatory Networks and on Trafficking of Non-T Cell Populations into the Cerebrospinal Fluid-Results from the ToFingo Successor Study

Leukocyte sequestration is an established therapeutic concept in multiple sclerosis (MS) as represented by the trafficking drugs natalizumab (NAT) and fingolimod (FTY). However, the precise consequences of targeting immune cell trafficking for immunoregulatory network functions are only incompletely understood. In the present study, we performed an in-depth longitudinal characterization of functional and phenotypic immune signatures in peripheral blood (PB) and cerebrospinal fluid (CSF) of 15 MS patients during switching from long-term NAT to FTY treatment after a defined 8-week washout period within a clinical trial (ToFingo successor study; ClinicalTrials.gov: NCT02325440). Unbiased visualization and analysis of high-dimensional single cell flow-cytometry data revealed that switching resulted in a profound alteration of more than 80% of investigated innate and adaptive immune cell subpopulations in the PB, revealing an unexpectedly broad effect of trafficking drugs on peripheral immune signatures. Longitudinal CSF analysis demonstrated that NAT and FTY both reduced T cell subset counts and proportions in the CSF of MS patients with equal potency; NAT however was superior with regard to sequestering non-T cell populations out of the CSF, including B cells, natural killer cells and inflammatory monocytes, suggesting that disease exacerbation in the context of switching might be driven by non-T cell populations. Finally, correlation of our immunological data with signs of disease exacerbation in this small cohort suggested that both (i) CD49d expression levels under NAT at the time of treatment cessation and (ii) swiftness of FTY-mediated effects on immune cell subsets in the PB together may predict stability during switching later on.

Recent advances in CD8+ regulatory T cell research

Various subgroups of CD8⁺ T lymphocytes do not only demonstrate cytotoxic effects, but also serve important regulatory roles in the body's immune response. In particular, CD8⁺ regulatory T cells (CD8⁺ Tregs), which possess important immunosuppressive functions, are able to effectively block the overreacting immune response and maintain the body's immune homeostasis. In recent years, studies have identified a small set of special CD8⁺ Tregs that can recognize major histocompatibility complex class Ib molecules, more specifically Qa-1 in mice and HLA-E in humans, and target the self-reactive CD4⁺ T ce lls. These findings have generated broad implications in the scientific community and attracted general interest to CD8⁺ Tregs. The present study reviews the recent research progress on CD8⁺ Tregs, including their origin, functional classification, molecular markers and underlying mechanisms of action.

Human Naive and Memory T Cells Display Opposite Migratory Responses to Sphingosine-1 Phosphate

The role of sphingosine-1 phosphate (S1P) in leukocyte trafficking has been well deciphered in mice but remains largely unaddressed in humans. In this study, we assessed the ex vivo response to S1P of primary human T cell subsets. We found that tonsil but not blood leukocytes were responsive to S1P gradients, suggesting that T cell responsiveness is regulated during their recirculation in vivo. Tonsil naive T cells were readily chemoattracted by S1P in an FTY720-sensitive, S1PR1-dependent manner. Surprisingly, S1P had the opposite effect on effector memory T cells, resident memory T cells, and recently activated T cells, inhibiting their spontaneous or chemokine-induced migration. This inhibition was also more pronounced for CD4 T cells than for CD8 T cell subsets, and was dependent on S1PR2, as shown using the S1PR2 antagonist JTE-013. S1PR1 was progressively downregulated during T cell differentiation whereas S1PR2 expression remained stable. Our results suggest that the ratio between S1PR1 and S1PR2 governs the migratory behavior of T cell subsets. They also challenge previous models of the role of S1P in lymphocyte recirculation and suggest that S1P promotes retention of memory T cell subsets in secondary lymphoid organs, via S1PR2.

Role of Immunological Memory Cells as a Therapeutic Target in Multiple Sclerosis

Pharmacological targeting of memory cells is an attractive treatment strategy in various autoimmune diseases, such as psoriasis and rheumatoid arthritis. Multiple sclerosis is the most common inflammatory disorder of the central nervous system, characterized by focal immune cell infiltration, activation of microglia and astrocytes, along with progressive damage to myelin sheaths, axons, and neurons. The current review begins with the identification of memory cell types in the previous literature and a recent description of the modulation of these cell types in T, B, and resident memory cells in the presence of different clinically approved multiple sclerosis drugs. Overall, this review paper tries to determine the potential of memory cells to act as a target for the current or newly-developed drugs.

Sphingolipid pathway enzymes modulate cell fate and immune responses

Sphingolipids (SLs) are a class of essential, bioactive lipids. The SL family includes over 4000 distinct molecules, characterized by their sphingoid base (long-chain aliphatic amine) backbone. SLs are key components of cell membranes, yet their roles go well beyond structure. SLs are involved in many cellular processes including cell differentiation, apoptosis, growth arrest and senescence. As cancer cells routinely display increased growth properties and escape from cell death, it has been suggested that enzymes involved in SL synthesis or catabolism may be altered in cancer cells. In this review, we discuss the role of SL pathway enzymes in cancer, and in acquired resistance to therapy. The use of inhibitors and gene silencing approaches targeting these SL pathways is also explored. Finally, we elaborate on the role of SL pathway enzymes in the tumor microenvironment and their effect on immune cell function.

Fingolimod hydrochloride for the treatment of relapsing remitting multiple sclerosis

INTRODUCTION

Fingolimod was the first oral and the first in class disease modifying treatment in multiple sclerosis that acts as sphingosine-1-phospathe receptor agonist. Since approval in 2010 there is a growing experience with fingolimod use in clinical practice, but also next-generation sphingosin-1-receptor agonists in ongoing clinical trials. Growing evidence demonstrates additional effects beyond impact on lymphocyte circulation, highlighting further promising targets in multiple sclerosis therapy. Areas covered: Here we present a systematic review using PubMed database searching and expert opinion on fingolimod use in clinical practice. Long-term data of initial clinical trials and post-marketing evaluations including long-term efficacy, safety, tolerability and management especially within growing disease modifying treatment options and pre-treatment constellation in multiple sclerosis patients are critically discussed. Furthermore novel findings in mechanism of actions and prospective on additional use in progressive forms in multiple sclerosis are presented. Expert opinion: There is an extensive long-term experience on fingolimod use in clinical practice demonstrating the favorable benefit-risk of this drug. Using a defined risk management approach experienced MS clinicians should apply fingolimod after critical choice of patients and review of clinical aspects. Further studies are essential to discuss additional benefit in progressive forms in multiple sclerosis.

Salutary effects of glibenclamide during the chronic phase of murine experimental autoimmune encephalomyelitis

Background

In multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), inflammation is perpetuated by both infiltrating leukocytes and astrocytes. Recent work implicated SUR1-TRPM4 channels, expressed mostly by astrocytes, in murine EAE. We tested the hypothesis that pharmacological inhibition of SUR1 during the chronic phase of EAE would be beneficial.

Methods

EAE was induced in mice using myelin oligodendrocyte glycoprotein (MOG) 35–55. Glibenclamide (10 μg/day) was administered beginning 12 or 24 days later. The effects of treatment were determined by clinical scoring and tissue examination. Drug within EAE lesions was identified using bodipy-glibenclamide. The role of SUR1-TRPM4 in primary astrocytes was characterized using patch clamp and qPCR. Demyelinating lesions from MS patients were studied by immunolabeling and immunoFRET.

Results

Administering glibenclamide beginning 24 days after MOG_35–55 immunization, well after clinical symptoms had plateaued, improved clinical scores, reduced myelin loss, inflammation (CD45, CD20, CD3, p65), and reactive astrocytosis, improved macrophage phenotype (CD163), and decreased expression of tumor necrosis factor (TNF), B-cell activating factor (BAFF), chemokine (C-C motif) ligand 2 (CCL2) and nitric oxide synthase 2 (NOS2) in lumbar spinal cord white matter. Glibenclamide accumulated within EAE lesions, and had no effect on leukocyte sequestration. In primary astrocyte cultures, activation by TNF plus IFNγ induced de novo expression of SUR1-TRPM4 channels and upregulated Tnf, Baff, Ccl2, and Nos2 mRNA, with glibenclamide blockade of SUR1-TRPM4 reducing these mRNA increases. In demyelinating lesions from MS patients, astrocytes co-expressed SUR1-TRPM4 and BAFF, CCL2, and NOS2.

Conclusions

SUR1-TRPM4 may be a druggable target for disease modification in MS.

Optimal response to dimethyl fumarate associates in MS with a shift from an inflammatory to a tolerogenic blood cell profile

BACKGROUND

The precise mechanism of action of dimethyl fumarate (DMF) treatment in MS remains unknown.

OBJECTIVE

To identify the changes in the blood lymphocyte profile of MS patients predicting no evidence of disease activity (NEDA) status after DMF treatment.

METHODS

We studied blood lymphocyte subsets of 64 MS patients treated with DMF at baseline and after 6 months of treatment by flow cytometry. NEDA (41 patients) or ongoing disease activity (ODA, 23 patients) were monitored after a year of follow-up.

RESULTS

During treatment, all patients experienced an increase in the naive T cells and a decrease in effector memory ones. However, only NEDA patients showed a significant reduction in central memory CD4+ and CD8+ T cells, memory B cells, CD4+ T cells producing interferon (IFN)-gamma, CD8+ T cells producing tumor necrosis factor-alpha (TNF-alpha), and IFN-gamma and B cells producing TNF-alpha. Additionally, they had an increase in regulatory CD56bright cells not observed in ODA group. After treatment, there was a negative correlation between CD56bright cells and CD8+ T cells producing IFN-gamma and TNF-alpha.

CONCLUSION

A pro-tolerogenic shift in the blood leukocyte profile associates with an optimal response to DMF in MS.

The Multiple Sclerosis (MS) Genetic Risk Factors Indicate both Acquired and Innate Immune Cell Subsets Contribute to MS Pathogenesis and Identify Novel Therapeutic Opportunities

Multiple sclerosis (MS) is known to be a partially heritable autoimmune disease. The risk of developing MS increases from typically 1 in 1,000 in the normal population to 1 in 4 or so for identical twins where one twin is affected. Much of this heritability is now explained and is due almost entirely to genes affecting the immune response. The largest and first identified genetic risk factor is an allele from the MHC class II HLA-DRB1 gene, HLA-DRB1*15:01, which increases risk about threefold. The HLA-DRB1 gene is expressed in antigen-presenting cells, and its protein functions in presenting particular types of antigen to CD4 T cells. This discovery supported the development of the first successful immunomodulatory therapies: glatiramer acetate, which mimics the antigen presentation process, and interferon beta, which targets CD4 T cell activation. Over 200 genetic risk variants, all single nucleotide polymorphisms (SNPs), have now been described. The SNPs are located within, or close to, genes expressed predominantly in acquired and innate immune cell subsets, indicating that both contribute to MS pathogenesis. The risk alleles indicate variation in the regulation of gene expression, rather than protein variation, underpins genetic susceptibility. In this review, we discuss how the expression and function of the risk genes, as well as the effect on these of the risk SNPs, indicate specific acquired immune cell processes that are the target of current successful therapies, and also point to novel therapeutic approaches.

Unexpected exacerbations following initiation of disease-modifying drugs in neuromyelitis optica spectrum disorder: Which factor is responsible, anti-aquaporin 4 antibodies, B cells, Th1 cells, Th2 cells, Th17 cells, or others?

Some disease-modifying drugs for multiple sclerosis, which mainly act on T cells, are ineffective for neuromyelitis optica spectrum disorder and induce unexpected relapses. These include interferon beta, glatiramer acetate, fingolimod, natalizumab, and alemtuzumab. The cases reported here suggest that dimethyl fumarate, which reduces the number of Th1 and Th17 cells and induces IL-4-producing Th2 cells, is also unsuitable for neuromyelitis optica spectrum disorder, irrespective of anti-aquaporin 4 IgG serostatus. Although oral dimethyl fumarate with manageable adverse effects is easy to initiate in the early course of multiple sclerosis, special attention should be paid for atypical demyelinating cases.

Fingolimod alters the transcriptome profile of circulating CD4+ cells in multiple sclerosis

Multiple sclerosis is a demyelinating disease affecting the central nervous system. T cells are known to contribute to this immune-mediated condition. Fingolimod modulates sphingosine-1-phosphate receptors, thereby preventing the egress of lymphocytes, especially CCR7-expressing CD8+ and CD4+ T cells, from lymphoid tissues. Using Affymetrix Human Transcriptome Arrays (HTA 2.0), we performed a transcriptome profiling analysis of CD4+ cells obtained from the peripheral blood of patients with highly active relapsing-remitting multiple sclerosis. The samples were drawn before the first administration of fingolimod as well as 24 hours and 3 months after the start of therapy. Three months after treatment initiation, 890 genes were found to be differentially expressed with fold-change >2.0 and t-test p-value < 0.001, among them several microRNA precursors. A subset of 272 genes were expressed at lower levels, including CCR7 as expected, while 618 genes showed an increase in expression, e.g., CCR2, CX3CR1, CD39, CD58 as well as LYN, PAK1 and TLR2. To conclude, we studied the gene expression of CD4+ cells to evaluate the effects of fingolimod treatment, and we identified 890 genes to be altered in expression after continuous drug administration. T helper cells circulating in the blood during fingolimod therapy present a distinct gene expression signature.

Severe disease exacerbations in patients with multiple sclerosis after discontinuing fingolimod

Discontinuation of fingolimod in patients with multiple sclerosis (MS) can lead to disease reactivation. In this review, we describe cases of severe exacerbations in patients with MS following discontinuation of fingolimod, including three cases from our center. We consider potential mechanisms of disease reactivation after cessation of fingolimod, and the evidence supporting this rebound effect. We conclude that discontinuation of fingolimod results in the return of disease activity, which then leads to severe exacerbations (i.e., rebounds) in a clinically significant proportion of patients. Lastly, we consider disease-modifying treatment options for patients who discontinue fingolimod.

Effects of multiple-dose ponesimod, a selective S1P1 receptor modulator, on lymphocyte subsets in healthy humans

This study investigated the effects of ponesimod, a selective S1P₁ receptor modulator, on T lymphocyte subsets in 16 healthy subjects. Lymphocyte subset proportions and absolute numbers were determined at baseline and on Day 10, after once-daily administration of ponesimod (10 mg, 20 mg, and 40 mg each consecutively for 3 days) or placebo (ratio 3:1). The overall change from baseline in lymphocyte count was -1,292±340×10⁶ cells/L and 275±486×10⁶ cells/L in ponesimod- and placebo-treated subjects, respectively. This included a decrease in both T and B lymphocytes following ponesimod treatment. A decrease in naïve CD4⁺ T cells (CD45RA⁺CCR7⁺) from baseline was observed only after ponesimod treatment (-113±98×10⁶ cells/L, placebo: 0±18×10⁶ cells/L). The number of T-cytotoxic (CD3⁺CD8⁺) and T-helper (CD3⁺CD4⁺) cells was significantly altered following ponesimod treatment compared with placebo. Furthermore, ponesimod treatment resulted in marked decreases in CD4⁺ T-central memory (CD45RA^-CCR7⁺) cells (-437±164×10⁶ cells/L) and CD4⁺ T-effector memory (CD45RA^-CCR7^-) cells (-131±57×10⁶ cells/L). In addition, ponesimod treatment led to a decrease of -228±90×10⁶ cells/L of gut-homing T cells (CLA^-integrin β7⁺). In contrast, when compared with placebo, CD8⁺ T-effector memory and natural killer (NK) cells were not significantly reduced following multiple-dose administration of ponesimod. In summary, ponesimod treatment led to a marked reduction in overall T and B cells. Further investigations revealed that the number of CD4⁺ cells was dramatically reduced, whereas CD8⁺ and NK cells were less affected, allowing the body to preserve critical viral-clearing functions.

Temporal kinetics of CD8+ CD28+ and CD8+ CD28- T lymphocytes in the injured rat spinal cord

This study aims to explore the temporal changes of cytotoxic CD8⁺ CD28⁺ and regulatory CD8⁺ CD28^- T-cell subsets in the lesion microenvironment after spinal cord injury (SCI) in rats, by combination of immunohistochemistry (IHC) and flow cytometry (FCM). In the sham-opened spinal cord, few CD8⁺ T cells were found. After SCI, the CD8⁺ T cells were detected at one day post-injury (dpi), then markedly increased and were significantly higher at 3, 7, and 14 dpi compared with one dpi (p < 0.01), the highest being seven dpi. In CD8⁺ T cells, more than 90% were CD28⁺ , and there were only small part of CD28^- ( < 10%). After 14 days, the infiltrated CD8⁺ T cells were significantly decreased, and few could be found in good condition at 21 and 28 dpi. Annexin V and propidium iodide (PI) staining showed that the percentages of apoptotic/necrotic CD8⁺ cells at 14 dpi and 21 dpi were significantly higher than those of the other early time-points (p < 0.01). These results indicate that CD8⁺ T cells could rapidly infiltrate into the injured spinal cords and survive two weeks, however, cytotoxic CD8⁺ T cells were dominant. Therefore, two weeks after injury might be the "time window" for treating SCI by prolonging survival times and increasing the fraction of CD8⁺ regulatory T-cells. © 2016 Wiley Periodicals, Inc.

Altered T cell phenotypes associated with clinical relapse of multiple sclerosis patients receiving fingolimod therapy

Multiple sclerosis (MS) is a T cell-mediated autoimmune disease. Fingolimod, a highly effective disease-modifying drug for MS, retains CCR7⁺ central memory T cells in which autoaggressive T cells putatively exist, in secondary lymphoid organs, although relapse may still occur in some patients. Here, we analyzed the T cell phenotypes of fingolimod-treated, fingolimod-untreated patients, and healthy subjects. The frequency of CD56⁺ T cells and granzyme B-, perforin-, and Fas ligand-positive T cells significantly increased during fingolimod treatment. Each T cell subpopulation further increased during relapse. Interestingly, T cells from fingolimod-treated patients exhibited interferon-γ biased production, and more myelin basic protein-reactive cells was noted in CD56⁺ than in CD56⁻ T cells. It is likely that the altered T cell phenotypes play a role in MS relapse in fingolimod-treated patients. Further clinical studies are necessary to investigate whether altered T cell phenotypes are a biomarker for relapse under fingolimod therapy.

High-Resolution Expression Profiling of Peripheral Blood CD8+ Cells in Patients with Multiple Sclerosis Displays Fingolimod-Induced Immune Cell Redistribution

Fingolimod, a sphingosine-1-phosphate (S1P) receptor modulator, is an oral drug approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). It selectively inhibits the egress of lymphocytes from lymph nodes. We studied the changes in the transcriptome of peripheral blood CD8⁺ cells to unravel the effects at the molecular level during fingolimod therapy. We separated CD8⁺ cells from the blood of RRMS patients before the first dose of fingolimod as well as 24 h and 3 months after the start of therapy. Changes in the expression of coding and non-coding genes were measured with high-density Affymetrix Human Transcriptome Array (HTA) 2.0 microarrays. Differentially expressed genes in response to therapy were identified by t test and fold change and analyzed for their functions and molecular interactions. No gene was expressed at significantly higher or lower levels 24 h after the first administration of fingolimod compared to baseline. However, after 3 months of therapy, 861 transcripts were found to be differentially expressed, including interleukin and chemokine receptors. Some of the genes are associated to the S1P pathway, such as the receptor S1P5 and the kinase MAPK1, which were significantly increased in expression. The fingolimod-induced transcriptome changes reflect a shift in the proportions of CD8⁺ T cell subsets, with CCR7^- effector memory T cells being relatively increased in frequency in the blood of fingolimod-treated patients. In consequence, CCR7 mRNA levels were reduced by >80 % and genes involved in T cell activation and lymphocyte cytotoxicity were increased in expression. Gene regulatory programs caused by downstream S1P signaling had only minor effects.

The dynamics of mucosal-associated invariant T cells in multiple sclerosis

Background

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory demyelination, gliosis and axonal loss in the Central Nervous System. Although the etiology of the disease has remained enigmatic, recent studies have suggested a role of the innate-like T cells, called Mucosal Associated Invariant T cells (MAITs) in the pathophysiology. In the present study, we have analyzed the relative frequency of MAITs and the expression of the cell surface antigens in MAITs to seek a possible link to the disease.

Results

There was little difference in the frequency of total MAITs between healthy donors (HDs) and untreated MS patients, whereas the latter harbored more CD8^lo/neg (DN) MAITs concomitant with a decrease in CD8^high MAITs and in CD4 MAITs compared with those in HDs. While the expression of CCR5, CCR6, CD95, CD127, and CD150 has increased in untreated subjects compared with that in HDs, CD45RO has declined in untreated subjects in both DN MAITs and CD8^hi MAITs. FTY720 therapy has increased the relative frequency of total MAITs in a time-dependent fashion up to 2 years. Intriguingly, FTY720 therapy for 3 years reversed the above phenotype, engendering more CD8^high MAITs accompanied with decreased DN MAITs. FTY720 therapy affected the cytokine production from CD4 T cells and also enhanced the relative frequency of cells producing both TNF-α and IFN-γ from MAITs, CD8 T cells, and CD4 T cells compared with that in untreated subjects.

Conclusions

FTY 720 therapy enhanced the relative frequency of MAITs in MS patients in a time-dependent manner. Although the expression of CD8 in MAITs has been affected early by FTY720, longer treatment has reversed the phenotypic change. These data demonstrated that FTY720 induced dynamic change in the relative frequency and in the phenotype of MAITs in MS.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2923-9) contains supplementary material, which is available to authorized users.

Effects of sphingosine-1-phosphate receptor 1 phosphorylation in response to FTY720 during neuroinflammation

Fingolimod (FTY720, Gilenya), a sphingosine-1-phosphate receptor (S1PR) modulator, is one of the first-line immunomodulatory therapies for treatment of relapsing-remitting multiple sclerosis (MS). Human S1PR1 variants have been reported to have functional heterogeneity in vitro, suggesting that S1PR1 function may influence FTY720 efficacy. In this study, we examined the influence of S1PR1 phosphorylation on response to FTY720 in neuroinflammation. We found that mice carrying a phosphorylation-defective S1pr1 gene [S1PR1(S5A) mice] were refractory to FTY720 treatment in MOG_35-55-immunized and Th17-mediated experimental autoimmune encephalomyelitis (EAE) models. Long-term treatment with FTY720 induced significant lymphopenia and suppressed Th17 response in the peripheral immune system via downregulating STAT3 phosphorylation in both WT and S1PR1(S5A) mice. However, FTY720 did not effectively prevent neuroinflammation in the S1PR1(S5A) EAE mice as a result of encephalitogenic cells expressing C-C chemokine receptor 6 (CCR6). Combined treatment with FTY720 and anti-CCR6 delayed disease progression in S1PR1(S5A) EAE mice, suggesting that CCR6-mediated cell trafficking can overcome the effects of FTY720. This work may have translational relevance regarding FTY720 efficacy in MS patients and suggests that cell type-specific therapies may enhance therapeutic efficacy in MS.

Clinical pharmacology, efficacy, and safety aspects of sphingosine-1-phosphate receptor modulators

INTRODUCTION

Sphingosine-1-phosphate (S1P) receptor modulators, of which one has received marketing approval and several others are in clinical development, display promising potential in the treatment of a spectrum of autoimmune diseases.

AREAS COVERED

Administration of S1P1 receptor modulators leads to functional receptor antagonism triggering sustained inhibition of the egress of lymphocytes from lymphoid organs. First-dose administration is associated with transient cardiovascular effects. We compiled and discussed available pharmacokinetic, pharmacodynamic, and safety data of selective and non-selective S1P receptor modulators that were investigated in recent years.

EXPERT OPINION

The safety profile of S1P receptor modulators is considered better than other classes of immunomodulators and was further improved by the development of up-titration regimens to mitigate first-dose effects. S1P receptor modulators display similar pharmacodynamic effects but have very different pharmacokinetic profiles. Drugs with a rapid elimination are of interest in case of opportunistic infections or pregnancy, whereas the need of re-initiation of up-titration in case of treatment interruption can present a challenge.

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.

Differences in common heritable blood immune cell populations may underlie MS susceptibility and progression

A promising new avenue of MS research that may lead to a better understanding of pathogenesis, progression and therapeutic response, and to development of new therapies, comes from the recent identification of defined immune cell populations that are highly heritable. Such stable populations have been identified in three recent papers using extensive flow cytometric panels to investigate twin and family cohorts. They showed that while most of the variation in immune cell populations between individuals was not heritable, some was. This heritability was sometimes very high, and the authors concluded that it likely contributes to variability in response among individuals for disease and drug response traits.

Sphingosine-1-Phosphate Signaling in Immune Cells and Inflammation: Roles and Therapeutic Potential

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite involved in many critical cell processes. It is produced by the phosphorylation of sphingosine by sphingosine kinases (SphKs) and exported out of cells via transporters such as spinster homolog 2 (Spns2). S1P regulates diverse physiological processes by binding to specific G protein-binding receptors, S1P receptors (S1PRs) 1-5, through a process coined as "inside-out signaling." The S1P concentration gradient between various tissues promotes S1PR1-dependent migration of T cells from secondary lymphoid organs into the lymphatic and blood circulation. S1P suppresses T cell egress from and promotes retention in inflamed peripheral tissues. S1PR1 in T and B cells as well as Spns2 in endothelial cells contributes to lymphocyte trafficking. FTY720 (Fingolimod) is a functional antagonist of S1PRs that induces systemic lymphopenia by suppression of lymphocyte egress from lymphoid organs. In this review, we summarize previous findings and new discoveries about the importance of S1P and S1PR signaling in the recruitment of immune cells and lymphocyte retention in inflamed tissues. We also discuss the role of S1P-S1PR1 axis in inflammatory diseases and wound healing.

Dimethyl fumarate selectively reduces memory T cells in multiple sclerosis patients

BACKGROUND

Dimethyl fumarate (DMF) alters the phenotype of circulating immune cells and causes lymphopenia in a subpopulation of treated multiple sclerosis (MS) patients.

OBJECTIVE

To phenotypically characterize circulating leukocytes in DMF-treated MS patients.

METHODS

Cross-sectional observational comparisons of peripheral blood from DMF-treated MS patients (n = 17 lymphopenic and n = 24 non-lymphopenic), untreated MS patients (n = 17) and healthy controls (n = 23); immunophenotyped using flow cytometry. Longitudinal samples were analyzed for 13 DMF-treated patients.

RESULTS

Lymphopenic DMF-treated patients had significantly fewer circulating CD8(+) and CD4(+) T cells, CD56(dim) natural killer (NK) cells, CD19(+) B cells and plasmacytoid dendritic cells when compared to controls. CXCR3(+) and CCR6(+) expression was disproportionately reduced among CD4(+) T cells, while the proportion of T-regulatory (T-reg) cells was unchanged. DMF did not affect circulating CD56(hi) NKcells, monocytes or myeloid dendritic cells. Whether lymphopenic or not, DMF-treated patients had a lower proportion of circulating central and effector memory T cells and concomitant expansion of naïve T cells compared to the controls.

CONCLUSIONS

DMF shifts the immunophenotypes of circulating T cells, causing a reduction of memory cells and a relative expansion of naïve cells, regardless of the absolute lymphocyte count. This may represent one mechanism of action of the drug. Lymphopenic patients had a disproportionate loss of CD8(+) T-cells, which may affect their immunocompetence.