Myelin-oligodendrocyte-glycoprotein (MOG) autoantibodies as potential markers of severe optic neuritis and subclinical retinal axonal degeneration.

Antibodies against conformation-dependent epitopes of myelin-oligodendrocyte-glycoprotein (MOG-abs) are present in subgroups of neuromyelitis optica spectrum disorder (NMOSD), recurrent optic neuritis (rON), multiple sclerosis (MS), and anti-NMDAR encephalitis. Using optical coherence tomography (OCT) we assessed whether MOG-abs might serve as potential marker of retinal axonal degeneration. We investigated a clinically heterogeneous cohort of 13 MOG-abs-positive patients (4 MOG-abs-positive rON, 4 MOG-abs-positive adult MS, 3 MOG-abs-positive relapsing encephalomyelitis, 2 MOG-abs-positive aquaporin-4-abs-negative NMOSD). As controls, we studied 13 age, sex and ON episode(s)-matched MOG-abs and aquaporin-4-abs-negative (AQP4-abs-negative) MS patients and 13 healthy controls (HC). In addition, we investigated 19 unmatched AQP4-abs-positive MOG-abs-negative NMOSD subjects. Considering all eyes, global pRNFL [in µm, mean (SD)] was significantly reduced in MOG-abs-positive patients [72.56 (22.71)] compared to MOG-abs-negative MS [80.81 (13.55), p = 0.0128], HCs [103.54 (8.529), p = 0.0014] and NMOSD [88.32 (18.43), p = 0.0353]. Non ON eyes from MOG-abs-positive subjects showed significant subclinical atrophy of temporal pRNFL quadrants. Microcystic macular edema (MME) was observed only in eyes of MOG-abs-positive (24%) and AQP4-abs-positive NMOSD (5.6%), but not in MOG-abs-negative MS or HC (p < 0.01). MOG-abs may serve as potential marker of retinal degeneration. Specifically, MOG-abs-related OCT features predominate in temporal pRNFL quadrants (resembling the MS retinal pattern), might be more severe than AQP4-abs-positive NMOSD, indicate subclinical pathology, and may be associated with MME.

Antibodies to MOG are transient in childhood acute disseminated encephalomyelitis.

OBJECTIVE: To study the longitudinal dynamics of anti-myelin oligodendrocyte glycoprotein (MOG) autoantibodies in childhood demyelinating diseases. METHODS: We addressed the kinetics of anti-MOG immunoglobulins in a prospective study comprising 77 pediatric patients. This was supplemented by a cross-sectional study analyzing 126 pediatric patients with acute demyelination and 62 adult patients with multiple sclerosis (MS). MOG-transfected cells were used for detection of antibodies by flow cytometry. RESULTS: Twenty-five children who were anti-MOG immunoglobulin (Ig) positive at disease onset were followed for up to 5 years. Anti-MOG antibodies rapidly and continuously declined in all 16 monophasic patients with acute disseminated encephalomyelitis and in one patient with clinically isolated syndrome. In contrast, in 6 of 8 patients (75%) eventually diagnosed with childhood MS, the antibodies to MOG persisted with fluctuations showing a second increase during an observation period of up to 5 years. Antibodies to MOG were mainly IgG 1 and their binding was largely blocked by pathogenic anti-MOG antibodies derived from a spontaneous animal model of autoimmune encephalitis. The cross-sectional part of our study elaborated that anti-MOG Ig was present in about 25% of children with acute demyelination, but in none of the pediatric or adult controls. Sera from 4/62 (6%) adult patients with MS had anti-MOG IgG at low levels. CONCLUSIONS: The persistence or disappearance of antibodies to MOG may have prognostic relevance for acute childhood demyelination.

Long-term follow-up of patients with neuromyelitis optica after repeated therapy with rituximab.

BACKGROUND: Neuromyelitis optica (NMO) is a severe autoimmune disease targeting optic nerves and spinal cord. The monoclonal anti-CD20 B-cell antibody rituximab is an emerging therapeutic option in NMO. However, neither long-term efficacy or safety of rituximab, nor the correlation between B-cell counts, B-cell fostering cytokines, aquaporin-4 antibodies (AQP4-ab), and disease activity in NMO, have been investigated prospectively. METHODS: We performed a prospective long-term cohort study of 10 patients with NMO who were treated up to 5 times with rituximab as a second-line therapy. Clinical examinations, B-cell counts, and serum concentrations of BAFF (B-cell activating factor of the TNF family; also called TNFSF13b), APRIL (a proliferation-inducing ligand; also called TNFSF13), AQP4-ab, and immunoglobulin levels were measured every 3 months. RESULTS: Repeated treatment with rituximab led to sustained clinical stabilization in most patients with NMO. Disease activity correlated with B-cell depletion, but not clearly with AQP4-ab or levels of APRIL. BAFF levels increased after application of rituximab and indicated persisting efficacy of the drug but did not correlate with disease activity. Overall, rituximab was well-tolerated even after up to 5 consecutive treatment courses; however, we observed several severe adverse reactions. CONCLUSION: Our data indicate that long-term therapy with rituximab is effective in NMO as a second-line therapy and has an acceptable safety profile. Retreatment with rituximab should be applied before reappearance of circulating B cells. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that repeated doses of rituximab result in stabilization in most patients.

Neuro-immune crosstalk in CNS diseases.

Immune cells infiltrate the CNS in many neurological diseases with a primary or secondary inflammatory component. In the CNS, immune cells employ shared mediators to promote crosstalk with neuronal cells. The net effect of this neuro-immune crosstalk critically depends on the context of the interaction. It has long been established that inflammatory reactions in the CNS can cause or augment tissue injury in many experimental paradigms. However emerging evidence suggests that in other paradigms inflammatory cells can contribute to neuroprotection and repair. This dual role of CNS inflammation is also reflected on the molecular level as it is becoming increasingly clear that immune cells can release both neurodestructive and neuroprotective molecules in CNS lesions. It is thus the balance between destructive and protective factors that ultimately determines the net result of the neuro-immune interaction.

Natalizumab disproportionately increases circulating pre-B and B cells in multiple sclerosis.

BACKGROUND: Natalizumab, a humanized anti-alpha4 integrin monoclonal antibody, reduces relapses and disease progression in patients with multiple sclerosis (MS). Whereas its presumed mode of action is inhibition of T cell/monocyte entry into the brain, little is known about its specific effect on B cells, which are increasingly recognized to participate in MS pathogenesis. METHODS: We obtained serial blood samples from 17 patients before and during natalizumab therapy for relapsing-remitting MS for up to 16 months, and blood samples from 10 untreated patients with MS and 13 healthy donors. We determined numbers of mature and immature lymphocyte subsets by flow cytometry for CD3, CD4, CD8, CD19, CD138, and CD10 in 111 samples. We analyzed marker transcripts for immature hematopoietic cells by quantitative PCR for CD34, Vprebeta1 (pre-B lymphocyte gene 1), and DNTT (terminal deoxynucleotidyltransferase) in 65 samples. RESULTS: Natalizumab therapy increased CD19(+) mature B cells more than other lymphocytes/monocytes in blood (2.8-fold versus 1.3-1.8-fold increase in cells/microL; p < 0.01). Even greater was the increase of immature CD19(+)CD10(+) pre-B cells (7.4-fold; p < 0.01). This pattern remained stable during treatment for up to 16 months. Transcripts of lymphocyte precursors (Vprebeta1 and DNTT) were elevated more than transcripts for CD34. CONCLUSIONS: Circulating B cells and especially pre-B cells are most prominently elevated among the studied immune cell subsets, raising the possibility that the effects and side effects of natalizumab are partly mediated by actions on B cells.

Interferon-beta increases BAFF levels in multiple sclerosis: implications for B cell autoimmunity.

B cells are increasingly recognized as major players in multiple sclerosis pathogenesis. The BAFF/APRIL system is crucial for B cell homoeostasis and may drive B cell-dependent autoimmunity. We asked whether this system is affected by Interferon (IFN)-beta therapy. We analysed transcription of the ligands (BAFF, APRIL, TWE-PRIL) and the corresponding receptors (BAFF-R, TACI and BCMA) by TaqMan-PCR ex vivo in whole blood and in immune cell subsets purified from IFN-beta-treated multiple sclerosis patients. Serum BAFF concentrations were determined by ELISA. This cross-sectional study involved 107 donors. IFN-beta therapy strongly induced BAFF transcription proportionally to the IFN-beta biomarker MxA in monocytes and granulocytes in vivo. BAFF serum concentrations were elevated in IFN-beta-treated multiple sclerosis patients to a similar level as observed in SLE patients. In cultured PBMC, neutrophils, fibroblasts and astrocytes, BAFF was induced by IFN-beta concentrations similar to those reached in vivo in treated multiple sclerosis patients. BAFF turned out to be the main regulated element of the BAFF/APRIL system. In untreated multiple sclerosis patients, there was no BAFF increase as compared to healthy controls. Our study reveals a complex situation. We show that IFN-beta therapy induces a potent B cell survival factor, BAFF. However, B cell depletion would be desirable at least in some multiple sclerosis patients. The systemic induction of BAFF by IFN-beta therapy may facilitate the production of various autoantibodies and of IFN-neutralizing antibodies. Individual MS/NMO patients who have major B cell involvement may benefit less than others from IFN-beta therapy, thus explaining interindividual differences of the therapeutic response.

CCL19 is constitutively expressed in the CNS, up-regulated in neuroinflammation, active and also inactive multiple sclerosis lesions.

CCL19 and CCL21 bind to CCR7, which is crucial for both inducing an immune response and establishing immunological tolerance. We report that in the normal human brain CCL19, but not CCL21, is transcribed, and detectable as a protein in tissue lysates and in cerebrospinal fluid. In both active and inactive multiple sclerosis (MS) lesions CCL19 transcripts were elevated. In cerebrospinal fluid from MS and OIND patients CCL19 protein was increased. In relapsing-remitting and secondary progressive MS patients CCL19 correlated with intrathecal IgG production. This study suggests that CCL19 plays a role in both the physiological immunosurveillance of the healthy CNS and the pathological maintenance of immune cells in the CNS of MS patients.

Herpesviral proteins regulating apoptosis.

The induction of apoptosis of virus-infected cells is an important defense mechanism of the host. Apoptosis of an infected cell can be induced cell autonomously as a consequence of viral replication or can be mediated by CTLs attacking the infected cells. Herpesviruses have developed different strategies to interfere with cell-autonomous apoptosis and to block CTL-induced apoptosis mediated by death receptors such as Fas and TRAIL. Herpesviruses, which establish a lifelong persistence in the infected host, can be found principally in two different conditions, episomal persistence with a limited number of genes expressed and lytic replication with expression of almost all genes. To meet the need of the virus to enhance survival of the infected cell, herpesviruses have evolved different strategies that function during both episomal persistence and lytic replication. Herpesviruses, which encode 70 to more than 200 genes have incorporated cell homologous antiapoptotic genes, they code for multifunctional genes that can also regulate apoptosis, and, finally, they modulate the expression of cellular apoptosis-regulating genes to favor survival of the infected cells. Viral interference with host cell apoptosis enhances viral replication, facilitates virus spread and persistence, and may promote the development of virus-induced cancer.

Treatment with glatiramer acetate induces specific IgG4 antibodies in multiple sclerosis patients.

We analysed the humoral immune response to glatiramer acetate (GA, Copaxone) in 20 multiple sclerosis patients treated with GA, 20 patients not treated with GA and 20 normal control subjects. Using an ELISA for detection of total GA-reactive immunoglobulins (all isotypes), all treated patients but also 3/20 untreated and 8/20 healthy subjects scored positive at 1:20 plasma dilutions. At higher dilutions, 5/20 treated patients and two healthy donors had relatively high levels of anti-GA antibodies. Isotype and IgG subclass analysis revealed that the two antibody-positive normal subjects had IgM and small titers of IgG1 or IgG2 antibodies. In contrast, 18 of 20 GA-treated patients, had low but significant titers of GA-reactive IgG4 antibodies. This finding is consistent with the previously described GA-mediated induction of T-helper 2 (TH2)-like regulatory T cells.

[Multiple sclerosis. Chlamydia hypothesis in debate]. / Multiple Sklerose. Chlamydien-Hypothese in der Diskussion.

Recently, an association between multiple sclerosis and Chlamydia pneumoniae infection has been suggested. Because standardized PCR protocols are lacking, a series of studies could not clarify whether C. pneumoniae is present in brain tissue and CSF of MS patients. Therefore, other studies focused on the humoral immune response against C. pneumoniae: 24% of MS patients, but only 5% of the control patients showed intrathecally produced antibodies against C. pneumoniae. If an infection with C. pneumoniae was involved in the pathogenesis of MS, one would expect that, in analogy to other infections of the CNS, the oligoclonal bands in the CSF of MS patients would recognize the responsible agent. However, the results we obtained by affinity-mediated immunoblots showed that the oligoclonal bands in the CSF of MS patients are not directed against Chlamydia antigen. In contrast to this, we found that the immunoglobulins in the CSF of neuroborreliosis patients reacted strongly against Borrelia antigen in the affinity-mediated immunoblots. In light of these results we assume that the intrathecal immunoglobulin production against C. pneumoniae is part of a polyspecific immune response. Thus, it is not likely that C. pneumoniae is causally linked to the pathogenesis of multiple sclerosis.

Signaling lymphocytic activation molecule (SLAM) regulates T cellular cytotoxicity.

Signaling lymphocytic activation molecule (SLAM) is a CD2-related surface receptor expressed by activated T cells and B cells. SLAM is a self ligand and enhances T cellular proliferation and IFN-gamma production. A defective SLAM associated protein (SAP) causes X-linked lymphoproliferative syndrome (XLP), a frequently lethal mononucleosis based on the inability to control EBV. We report that SLAM augments TCR-mediated cytotoxicity. In normal CD4(+) and CD8(+) T cells, SLAM enhanced TCR-mediated cytotoxicity. In CD4(+) and CD8(+) Herpesvirus saimiri (H.saimiri) infected T cells, SLAM engagement alone triggered cytotoxicity. Using H.saimiri-transformed T cells as a model system we found that SLAM-engagement promotes the release of lytic granules and a CD95-independent killing that requires extracellular Ca(2+), cytoskeletal rearrangements, and signaling mediated by mitogen-activated protein kinase kinases MEK1/2. SLAM-enhanced cytotoxicity implies an immunoregulatory function by facilitating the elimination of APC and a role in overcoming infections with pathogens requiring a cytotoxic immune response.

Signaling lymphocytic activation molecule is expressed on mature CD83+ dendritic cells and is up-regulated by IL-1 beta.

Signaling lymphocyte activation molecule (SLAM), a 70-kDa costimulatory molecule that mediates CD28-independent proliferation of T cells and IFN-gamma production, has been identified on human T cells, immature thymocytes, and a subset of B cells. We have found that SLAM is expressed on mature but not immature dendritic cells (DC). However, the SLAM-associated protein, is missing in DC. SLAM surface expression is strongly up-regulated by IL-1beta. Addition of IL-1beta to the DC maturation mixture also increases the stimulatory properties of DC. These findings provide a new marker for DC maturation and help to explain two areas of DC biology. First, SLAM is a receptor for the measles virus, previously shown to infect DC. Second, SLAM could possibly contribute to the enhanced immunostimulatory functions of DC that are observed following the addition of IL-1.

Herpesvirus saimiri replaces ZAP-70 for CD3- and CD2-mediated T cell activation.

The protein tyrosine kinase ZAP-70 plays a pivotal role involved in signal transduction through the T cell receptor and CD2. Defects in ZAP-70 result in severe combined immunodeficiency. We report that Herpesvirus saimiri, which does not code for a ZAP-70 homologue, can replace this tyrosine kinase. H. saimiri is an oncogenic virus that transforms human T cells to stable growth based on mutual CD2-mediated activation. Although CD2-mediated proliferation of ZAP-70-deficient uninfected T cells was absent, we could establish H. saimiri-transformed T cell lines from two unrelated patients presenting with ZAP-70 deficiencies. In these cell lines, CD2 and CD3 activation were restored in terms of [Ca(2+)](i), MAPK activation, cytokine production, and proliferation. Activation-induced tyrosine phosphorylation of zeta remained defective. The transformed cells expressed very high levels of the ZAP-70-related kinase Syk. This increased expression was not observed in the primary T cells from the patients and was not due to the transformation by the virus because transformed cell lines established from control T cells did not present this particularity. In conclusion, wild type H. saimiri can restore CD2- and CD3-mediated activation in signaling-deficient human T cells. It extends our understanding of interactions between the oncogenic H. saimiri and the infected host cells.

Interleukin-12 receptor beta1 deficiency in a patient with abdominal tuberculosis.

Two siblings with interleukin-12 receptor beta1 (IL-12Rbeta1) deficiency but different clinical phenotypes were studied. Both are homozygous for an IL12RB1 missense mutation that prevents receptor expression and abolishes cellular responses to IL-12. Transfection of the patients' T cells with wild-type IL12RB1 restored IL-12Rbeta1 expression and function. One patient had the expected phenotype of disseminated bacille Calmette-Guérin (BCG) infection in early childhood, whereas the other did not develop BCG infection, despite 3 inoculations with live BCG. Abdominal tuberculosis was diagnosed in this second patient at age 18 years. To date, neither of them has had clinical disease caused by environmental mycobacteria. These observations show unexpected interfamilial and intrafamilial heterogeneity of the clinical phenotype associated with IL-12Rbeta1 deficiency. The patients may be resistant to BCG but remain vulnerable to Mycobacterium tuberculosis. A diagnosis of IL-12Rbeta1 deficiency should therefore be considered in selected patients with severe tuberculosis, despite their resistance to BCG and a lack of atypical mycobacteriosis.

Herpesvirus saimiri transformed T cells and peripheral blood mononuclear cells restimulate identical antigen-specific human T cell clones.

Panels of human antigen-specific T cell clones (TCC) have been established by limiting dilution using Herpesvirus saimiri (HVS) subtype C transformed T cells as antigen presenting cells (APC). They showed antigen-specific proliferation when peripheral blood mononuclear cells (PBMC), HVS-transformed T cells and Epstein Barr Virus transformed lymphoblastoid B cell lines (EBV-LCL) were used as APC. All T cell clones were CD4+ and HLA class II restricted. For a detailed analysis, two panels of T cell clones specific for an epitope located in the N-terminus of the Merozoite Surface Protein 1 (MSP-1) of Plasmodium falciparum were established from the same founder T cell line using either PBMC or HVS-transformed T cells as APC. TCR analysis of the two panels of TCC demonstrated that the same founder cells could be propagated in both culture systems. Furthermore, no difference in the cytokine expression pattern or antigen processing and co-stimulatory requirements was observed between TCC established on PBMC or HVS-transformed T cells. Based on the finding that HVS-transformed T cells can replace PBMC as APC for isolation and propagation of antigen-specific TCC, a protocol was developed and successfully executed, which allows to establish and maintain vaccine-specific T cell clones from 20 ml of blood. This method might be particularly significant in clinical trials of immune intervention strategies.

Intrathecal antibody production against Chlamydia pneumoniae in multiple sclerosis is part of a polyspecific immune response.

Chronic intrathecal immunoglobulin (Ig) production is a hallmark of multiple sclerosis characterized by the presence of oligoclonal IgGs and, in addition, polyspecific recognition of different pathogens such as measles, rubella and herpes zoster virus. While the antigen specificity of the oligoclonal IgGs in multiple sclerosis is largely unknown, the oligoclonal IgGs arising during CNS infectious diseases are reactive against the specific pathogen. Recently, a link between Chlamydia pneumoniae and multiple sclerosis has been claimed. To test the possible role of C. pneumoniae in multiple sclerosis, we analysed (i) whether there is intrathecal IgG production against C. pneumoniae in multiple sclerosis and (ii) if the oligoclonal IgGs in the CSF of multiple sclerosis patients recognize C. pneumoniae. By studying paired serum-CSF samples from 120 subjects (definite multiple sclerosis, 46; probable multiple sclerosis, 12; other inflammatory neurological diseases, 35; other neurological diseases, 27) by enzyme-linked immunosorbent assay, we found that 24% of all patients with definite multiple sclerosis, but only 5% of patients with other inflammatory or non-inflammatory diseases, produced IgGs specific for C. pneumoniae intrathecally (definite multiple sclerosis versus other inflammatory neurological diseases: P = 0.027). The presence of intrathecal IgGs to C. pneumoniae was independent of the duration of disease and relatively stable over time. The major CSF oligoclonal IgG bands from multiple sclerosis patients with an intrathecal Ig production to C. pneumoniae did not react towards purified elementary bodies and reticulate bodies of C. pneumoniae on affinity-mediated immunoblot following isoelectric focusing (IEF-western blots). In contrast, the IgGs in the CSF of control patients with neuroborreliosis strongly reacted with their specific pathogen, Borrelia burgdorferi, by IEF-western blot analysis. Concomitant analysis of the CSF of 23 patients with a nested polymerase chain reaction for C. pneumoniae was negative in all cases. Together, our findings strongly suggest that the immune response to C. pneumoniae is part of a polyspecific intrathecal Ig production, as is commonly observed with other pathogens. This argues against a specific role for C. pneumoniae in multiple sclerosis.