Efficacy of the anti-IL-6 receptor antibody tocilizumab in neuromyelitis optica: a pilot study

Objective:

To evaluate the safety and efficacy of a humanized anti–interleukin-6 receptor antibody, tocilizumab (TCZ), in patients with neuromyelitis optica (NMO).

Methods:

Seven patients with anti–aquaporin-4 antibody (AQP4-Ab)-positive NMO or NMO spectrum disorders were recruited on the basis of their limited responsiveness to their current treatment. They were given a monthly injection of TCZ (8 mg/kg) with their current therapy for a year. We evaluated the annualized relapse rate, the Expanded Disability Status Scale score, and numerical rating scales for neurogenic pain and fatigue. Serum levels of anti-AQP4-Ab were measured with AQP4-transfected cells.

Results:

Six females and one male with NMO were enrolled. After a year of TCZ treatment, the annualized relapse rate decreased from 2.9 ± 1.1 to 0.4 ± 0.8 (p < 0.005). The Expanded Disability Status Scale score, neuropathic pain, and general fatigue also declined significantly. The ameliorating effects on intractable pain exceeded expectations.

Conclusion:

Interleukin-6 receptor blockade is a promising therapeutic option for NMO.

Classification of evidence:

This study provides Class IV evidence that in patients with NMO, TCZ reduces relapse rate, neuropathic pain, and fatigue.

Differential effects of fingolimod on B-cell populations in multiple sclerosis

BACKGROUND

Fingolimod is an oral drug approved for multiple sclerosis (MS) with an ability to trap central memory T cells in secondary lymphoid tissues; however, its variable effectiveness in individual patients indicates the need to evaluate its effects on other lymphoid cells.

OBJECTIVE

To clarify the effects of fingolimod on B-cell populations in patients with MS.

METHODS

We analysed blood samples from 9 fingolimod-treated and 19 control patients with MS by flow cytometry, to determine the frequencies and activation states of naive B cells, memory B cells, and plasmablasts.

RESULTS

The frequencies of each B-cell population in peripheral blood mononuclear cells (PBMC) were greatly reduced 2 weeks after starting fingolimod treatment. Detailed analysis revealed a significant reduction in activated memory B cells (CD38(int-high)), particularly those expressing Ki-67, a marker of cell proliferation. Also, we noted an increased proportion of activated plasmablasts (CD138(+)) among whole plasmablasts, in the patients treated with fingolimod.

CONCLUSIONS

The marked reduction of Ki-67(+) memory B cells may be directly linked with the effectiveness of fingolimod in treating MS. In contrast, the relative resistance of CD138(+) plasmablasts to fingolimod may be of relevance for understanding the differential effectiveness of fingolimod in individual patients.

Plasmablasts as migratory IgG-producing cells in the pathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO) is an inflammatory disease characterized by recurrent attacks of optic neuritis and myelitis. It is generally accepted that autoantibodies against aquaporin 4 water channel protein play a pathogenic role in neuromyelitis optica. We have recently reported that plasmablasts are increased in the peripheral blood of this autoimmune disease, and are capable of producing autoantibodies against aquaporin 4. Here, we demonstrate that CD138⁺HLA-DR⁺ plasmablasts, a subset of IgG-producing cells, are increased in the peripheral blood and are enriched among the cerebrospinal fluid (CSF) lymphocytes during the relapse of neuromyelitis optica. Notably, these CD138⁺HLA-DR⁺ plasmablasts overexpress CXCR3, whose ligands are present in the cerebrospinal fluid during the relapse of neuromyelitis optica. These results led us to speculate that plasmablasts producing anti-aquaporin 4 autoantibodies might traffic toward the central nervous system (CNS). Furthermore, we performed single-cell sorting of plasmablasts from peripheral blood and CSF samples from NMO and sequenced the complementarity-determining regions (CDRs) of the IgG heavy chain expressed by the sorted plasmablast clones. There were high frequencies of mutations in the CDRs compared with framework regions, indicating that these plasmablast clones would represent a post-germinal center B-cell lineage. Consistent with the preceding results, the plasmablast clones from the peripheral blood shared the same CDR sequences with the clones from the CSF. These results indicate that IgG-producing plasmablasts, which are guided by helper T-cells, may migrate from the peripheral blood preferentially to the CSF. Since migratory plasmablasts could be involved in the inflammatory pathology of NMO, the B-cell subset and their migration might be an attractive therapeutic target.

IL-7-Dependent Homeostatic Proliferation in the Presence of a Large Number of T Cells inGldMice

In gld mice, CD4 and 8-double-negative (DN) T cells as well as naive and memory-phenotype T cells accumulate in the peripheral lymphoid organs. Although Fas ligand (L) defect accounts for the progressive accumulation of abnormal DN T cells, the existence of other mechanisms which may be involved in the defective homeostasis in gld mice has been unclear. In this study, we analyze T-cell homeostasis in gld mice using adoptive transfer systems. It was shown that a gld, but not C57BL/6 (B6), environment led to augmented proliferation of B6 T cells transferred without up-regulation of CD69. Thus, the augmented T-cell proliferation seemed to result from mal-homeostatic proliferation even in the presence of a large number of recipient T cells. T cells from lpr mice showed no significant proliferation in the B6 environment, suggesting that the absence of Fas-Fas L interaction was not responsible for the mal-homeostatic proliferation. Although similar levels of IL-7 mRNA were detected in gld and B6 spleens, the intensity of CD127 and the proportion of CD127+ cells in the T cells were significantly lower in gld mice than in B6 mice, suggesting that IL-7 excess in a gld environment is responsible for the abnormal proliferation of transferred T cells. The administration of anti-CD127 antibody inhibited the proliferation of transferred lymphocytes. Thus, IL-7-dependent proliferation seems to be involved in the abnormal proliferation of lymphocytes in gld recipients.

[Pathogenesis of chronic inflammatory demyelinating polyneuropathy]

Chronic inflammatory demyelinating polyneuropathy (CIDP) is considered to be a demyelinating autoimmune disorder in the peripheral nervous system. Concerning cellular immune response, activity of IFN-gamma producing Th1 and IL-17 producing Th17 cells might be accelerated in patients with CIDP, while regulatory function of CD4+ CD25(high) Foxp3+ regulatory T cells might be diminished. Humoral immune responses against several myelin components such as myelin protein zero and gangliosides such as GM1 might be also induced in a part of patients with CIDP. Besides, growing body of evidences suggest that immune response against several molecules expressed in the noncompact myelin might be involved in the pathogenesis of CIDP.

CCR2(+)CCR5(+) T cells produce matrix metalloproteinase-9 and osteopontin in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS that is presumably mediated by CD4(+) autoimmune T cells. Although both Th1 and Th17 cells have the potential to cause inflammatory CNS pathology in rodents, the identity of pathogenic T cells remains unclear in human MS. Given that each Th cell subset preferentially expresses specific chemokine receptors, we were interested to know whether T cells defined by a particular chemokine receptor profile play an active role in the pathogenesis of MS. In this article, we report that CCR2(+)CCR5(+) T cells constitute a unique population selectively enriched in the cerebrospinal fluid of MS patients during relapse but not in patients with other neurologic diseases. After polyclonal stimulation, the CCR2(+)CCR5(+) T cells exhibited a distinct ability to produce matrix metalloproteinase-9 and osteopontin, which are involved in the CNS pathology of MS. Furthermore, after TCR stimulation, the CCR2(+)CCR5(+) T cells showed a higher invasive potential across an in vitro blood-brain barrier model compared with other T cells. Of note, the CCR2(+)CCR5(+) T cells from MS patients in relapse are reactive to myelin basic protein, as assessed by production of IFN-γ. We also demonstrated that the CCR6(-), but not the CCR6(+), population within CCR2(+)CCR5(+) T cells was highly enriched in the cerebrospinal fluid during MS relapse (p < 0.0005) and expressed higher levels of IFN-γ and matrix metalloproteinase-9. Taken together, we propose that autoimmune CCR2(+)CCR5(+)CCR6(-) Th1 cells play a crucial role in the pathogenesis of MS.

Clinical improvement in a patient with neuromyelitis optica following therapy with the anti-IL-6 receptor monoclonal antibody tocilizumab

Neuromyelitis optica (NMO) is a disabling autoimmune disease associated with an elevation of anti-aquaporin 4 (AQP4) autoantibodies. Here, we present a case with NMO who responded to monthly administration of the anti-IL-6 receptor antibody tocilizumab. The treatment rapidly reduced the elevated numbers of plasmablasts and anti-AQP4 autoantibodies in the patient. Furthermore, neuropathic pain and disability scores gradually improved. Tocilizumab may be considered as a therapeutic option for NMO.

Increase of Ki-67+ natural killer cells in multiple sclerosis patients treated with interferon-β and interferon-β combined with low-dose oral steroids

Interferon-β (IFN-β) is known to expand regulatory CD56(bright) natural killer (NK) cells in multiple sclerosis (MS). In this cross-sectional study we show that MS patients treated with IFN-β alone or in combination with low-dose prednisolone displayed increased proportion of all NK cell subsets in the active phase of the cell cycle (Ki-67+). There was no difference in NK cell apoptosis markers. In vitro experiments showed that both IFN-β and IFN-β in combination with corticosteroids increased the proportion of Ki-67(+) NK cells. This study, although limited, shows that treatment with IFN-β affects NK cell cycle without altering NK cell apoptosis in MS patients.

Th17 Cells and autoimmune encephalomyelitis (EAE/MS)

Multiple sclerosis (MS) is a CD4+ T cell-mediated autoimmune disease affecting the central nervous system. It was largely accepted that Th1 cells driven by IL-12 were pathogenic T cells in human MS and experimental autoimmune encephalomyelitis, an animal model of MS. Recent data have established that IL-17-producing CD4+ T cells, driven by IL-23 and referred to as Th17 cells, play a pivotal role in the pathogenesis of EAE. A combination of TGF-beta and IL-6 induce Th17 cell lineage commitment via expression of transcription factor RORgammat. Th17 cells and induced Foxp3+ T regulatory cells are in reciprocal position in the T cell lineage commitment governed by TGF-beta and IL-6. The vitamin A metabolite retinoic acid is involved in this process via TGF-beta dependent induction of Foxp3. We have demonstrated that human Th17 cells could be identified as CCR2+ CCR5- memory CD4+ T cells. It is becoming clear that IL-23/Th17 axis also plays an important role in the pathogenesis of various human autoimmune diseases including MS. Additionally, accumulating evidences raise a possibility that CCR2 on Th17 cells may be a therapeutic target in MS.

Cutting edge: Human Th17 cells are identified as bearing CCR2+CCR5- phenotype

Recent reports have shown that IL-17-producing CD4+ T cells (Th17 cells) belong to a distinct helper T cell lineage and are critically involved in the pathogenesis of autoimmune diseases and allergies. However, the chemokine receptor profile of Th17 cells remains to be clarified. In this study, we report that human Th17 cells are identified as CCR2+CCR5- memory CD4+ T cells. Analysis of PBMC from healthy donors showed that CCR2+ cells produce much larger amounts of IL-17 than CCR2- cells, indicating the preferential expression of CCR2 on Th17 cells. Notably, CCR2+CCR5- memory CD4+ T cells produced a large amount of IL-17 and little IFN-gamma, whereas CCR2+CCR5+ cells reciprocally produced an enormous amount of IFN-gamma but little IL-17. Moreover, a higher expression of T-bet was seen in the CCR5+ memory T cells. These results indicate that absence of CCR5 distinguishes human Th17 cells from Th1 cells.

Differential Expression of CD11c by Peripheral Blood NK Cells Reflects Temporal Activity of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease, showing a great degree of variance in temporal disease activity. We have recently demonstrated that peripheral blood NK cells biased for secreting IL-5 (NK2 bias) are associated with the remission state of MS. In this study, we report that MS patients in remission differentially express CD11c on NK cell surface (operationally defined as CD11chigh or CD11clow). When we compared CD11chigh or CD11clow patients, the expression of IL-5 and GATA-3 in NK cells supposed to endow a disease-protective NK2 phenotype was observed in CD11clow but not in CD11chigh patients. In contrast, the CD11chigh group showed a higher expression of HLA-DR on NK cells. In vitro studies demonstrated that NK cell stimulatory cytokines such as IL-15 would up-regulate CD11c expression on NK cells. Given previous evidence showing an association between an increased level of proinflammatory cytokines and temporal disease activity in MS, we postulate that inflammatory signals may play a role in inducing the CD11chigh NK cell phenotype. Follow-up of a new cohort of patients showed that 6 of 10 CD11chigh MS patients developed a clinical relapse within 120 days after evaluation, whereas only 2 of 13 CD11clow developed exacerbated disease (p = 0.003). As such, a higher expression of CD11c on NK cells may reflect the temporal activity of MS as well as a loss of regulatory NK2 phenotype, which may allow us to use it as a potential biomarker to monitor the immunological status of MS patients.

T cell gene expression profiling identifies distinct subgroups of Japanese multiple sclerosis patients

To clarify the molecular background underlying the heterogeneity of multiple sclerosis (MS), we characterized the gene expression profile of peripheral blood CD3+ T cells isolated from MS and healthy control (CN) subjects by using a cDNA microarray. Among 1258 cDNAs on the array, 286 genes were expressed differentially between 72 untreated Japanese MS patients and 22 age- and sex-matched CN subjects. When this set was used as a discriminator for hierarchical clustering analysis, it identified four distinct subgroups of MS patients and five gene clusters differentially expressed among the subgroups. One of these gene clusters was overexpressed in MS versus CN, and particularly enhanced in the clinically most active subgroup of MS. After 46 of the MS patients were treated with interferon-beta (IFNbeta-1b) for two years, IFNbeta responders were clustered in two of the four MS subgroups. Furthermore, the IFNbeta responders differed from nonresponders in the kinetics of IFN-responsive genes at 3 and 6 months after starting IFNbeta treatment. These results suggest that T-cell gene expression profiling is valuable to identify distinct subgroups of MS associated with differential disease activity and therapeutic response to IFNbeta.

The regulatory role of natural killer cells in multiple sclerosis

Multiple sclerosis is a chronic demyelinating disease of presumed autoimmune pathogenesis. The patients with multiple sclerosis typically shows alternating relapse and remission in the early stage of illness. We previously found that in the majority of multiple sclerosis patients in a state of remission, natural killer (NK) cells contain unusually high frequencies of the cells expressing CD95 (Fas) on their surface (>36.0%). Here we report that in such 'CD95+ NK-high' patients, NK cells may actively suppress potentially pathogenic autoimmune T cells that can mediate the inflammatory responses in the CNS. Using peripheral blood mononuclear cells (PBMCs) derived from 'CD95+ NK-high' or 'CD95+ NK-low' multiple sclerosis in a state of remission, we studied the effect of NK cell depletion on the memory T cell response to myelin basic protein (MBP), a major target antigen of multiple sclerosis. When we stimulated PBMCs of the 'CD95+ NK-high' multiple sclerosis after depleting CD56+ NK cells, a significant proportion of CD4+ T cells (1/2000 to 1/200) responded rapidly to MBP by secreting interferon (IFN)-gamma, whereas such a rapid T cell response to MBP could not be detected in the presence of NK cells. Nor did we detect the memory response to MBP in the 'CD95+ NK-low' multiple sclerosis patients in remission or healthy subjects, regardless of whether NK cells were depleted or not. Depletion of cells expressing CD16, another NK cell marker, also caused IFN-gamma secretion from MBP-reactive CD4+ T cells in the PBMCs from 'CD95+ NK-high' multiple sclerosis. Moreover, we showed that NK cells from 'CD95+ NK-high' multiple sclerosis could inhibit the antigen-driven secretion of IFN-gamma by autologous MBP-specific T cell clones in vitro. These results indicate that NK cells may regulate activation of autoimmune memory T cells in an antigen non-specific fashion to maintain the clinical remission in 'CD95(+) NK-high' multiple sclerosis patients.

Positive and negative selection of T cell repertoires during differentiation in allogeneic bone marrow chimeras

T cells acquire immune functions during expansion and differentiation in the thymus. Mature T cells respond to peptide antigens (Ag) derived from foreign proteins when these peptide Ag are presented on the self major histocompatibility complex (MHC) molecules but not on allo-MHC. This is termed self-MHC restriction. On the other hand, T cells do not induce aggressive responses to self Ag (self-tolerance). Self-MHC restriction and self-tolerance are not genetically determined but acquired a posteriori by positive and negative selection in the thymus in harmony with the functional maturation. Allogeneic bone marrow (BM) chimera systems have been a useful strategy to elucidate mechanisms underlying positive and negative selection. In this communication, the contribution of BM chimera systems to the investigation of the world of T-ology is discussed.

Tumour necrosis factor-alpha but not lipopolysaccharide enhances preference of murine dendritic cells for Th2 differentiation

Using murine spleen-derived dendritic cells (DC) and DO11.10 T cells specific for ovalbumin (OVA), the influences of maturational condition and antigen dose on the capability of DC to induce helper T-cell (Th) differentiation were analysed. Immature DC (iDC) with high- or low-dose OVA(323-339) predominantly induced Th1 or Th2 responses in DO11.10 T cells, respectively. DC matured by tumour necrosis factor-alpha (TNF/DC) induced a significantly higher Th2 response in the presence of low-dose OVA(323-339) than iDC and DC matured by lipopolysaccharide (LPS) (LPS/DC). In the presence of high-dose OVA(323-339), LPS/DC induced significantly lower levels of Th1 response than iDC. Under these conditions no difference in the Th1 response was noted between TNF/DC and iDC. The enhanced capability of TNF/DC with a low-dose antigen for Th2 polarization and the decreased preference of LPS/DC with a high-dose antigen to Th1 polarization were not related to the amount of IL-12 produced in these cultures. These results demonstrate for the first time that TNF/DC with a low-dose antigen are potent inducers of Th2 differentiation.

Syngeneic mixed lymphocyte reaction (SMLR) with dendritic cells: direct visualization of dividing T cell subsets in SMLR

Syngeneic mixed lymphocyte reaction (SMLR) has been considered to represent T cell response to self antigens. In this study using stimulator dendritic cells (DC), we analyzed cellular components responding to the syngeneic DC. It was shown that the predominant dividing cells were CD8(+) T cells although the response of CD4(+) T cells was essential for initiation of SMLR. In spite of the vigorous proliferation and expression of several activation markers, these SMLR-activated CD8(+) T cells hardly killed syngeneic targets and most of the CD8(+) T cells produced no interferon-gamma upon restimulation with DC. Furthermore, in SMLR where CD8(+) T cells were absent or inhibited, a considerable proliferation of CD4(-) CD8(-) double negative-T cells that included TCRalpha/beta(+) natural killer-T cells (NKT cells), TCRgamma/delta(+) NKT cells and TCRgamma/delta(+) T cells was observed.

[A study on T cell subsets responsible for syngeneic mixed lymphocyte reaction]

In vitro proliferation of T cells in response to the stimulation with syngeneic non-T cells has been regarded as the syngeneic mixed lymphocyte reaction (SMLR). SMLR has been considered to represent a characteristic of immunological response to the self antigen. It was demonstrated that the T cell subset proliferating in the SMLR belonged to CD4+ T cell population and was characterized as CD45RA+ memory Th cell subset. It has been postulated that CD8+ T cells are not significantly involved in the SMLR. In the present study, SMLR was analyzed with nylon-wool-purified splenic T cells as responders and splenic dendritic cells (DC) as stimulators. With the use of carboxyfluorescein diacetate succinimidyl ester (CFSE), it was demonstrated that the predominant proliferating subset was CD8+ T cell 3 days after the culture. However, when CD4+ T cells were depleted before SMLR, CD8+ T cells hardly proliferated. From the analysis of several activation markers, the proportion of the activated T cells was higher in the CD8+ T cells than in CD4+ T cells. For further elucidation of T cell subsets responsible for SMLR, responder cells which expressed CD62L, a marker for naive T cells, were examined. When CD62L+ and CD62L- T cells were cultured with DC, CD62L+ T cells generated vigorous proliferation, whereas CD62L- T cells showed quite low response. The present findings demonstrate that CD8+ T cells and/or CD62L+ T cells play certain roles in SMLR.