Francine Hoffmann

Altered expression of miR-17-5p in CD4+ lymphocytes of relapsing-remitting multiple sclerosis patients

MicroRNA (miRNA) are a class of post‐transcriptional regulators of gene expression targeting mRNA for translational repression and/or degradation. We analyzed the expression of 365 miRNA in lymphocytes in relapsing–remitting MS patients, and show the first evidence for distinct miRNA expression profiles in CD4+, CD8+ and B cells in MS when compared with those in healthy volunteers. MiR‐17‐5p, which is involved in autoimmunity, was up‐regulated in CD4+ cells from MS patients. This was correlated with alterations in the expression of potential target genes of miR‐17‐5p, i.e. phosphatase and tensin homology and phosphatidyl‐inositol‐3‐kinase regulatory subunit 1, which were down‐regulated upon stimulation of CD4+ cells with anti‐CD3/CD28 in vitro. Functional experiments with a synthetic inhibitor of miR‐17 supported the link between miRNA expression and the altered target gene expression. Moreover, we found distinct responses of deregulated miRNA to stimulation, i.e. miR‐17‐5p and miR‐193a were strongly up‐regulated, in contrast to the down‐regulation of miR‐497, miR‐1 and miR‐126. Other deregulated miRNA did not respond to the stimulation probably due to other, non‐T‐cell activation related, mechanisms in their mode of action. Our findings support the role of miRNA‐dependent regulatory mechanisms in the immunopathogenesis of MS.

Natalizumab alters transcriptional expression profiles of blood cell subpopulations of multiple sclerosis patients

Natalizumab, the most recently approved treatment for relapsing multiple sclerosis (MS) exerts its action through binding to alpha4 integrins. We studied longitudinally gene expression profiles in peripheral blood of MS patients, treated with natalizumab for more than 2 years. The majority of altered genes relates to immune response, signal transduction, adhesion and metabolism. Not only gene expression relevant for T lymphocytes was altered, but also genes regulating B-lymphocyte, neutrophil and erythrocyte functions. Understanding these different gene effects and their interrelationships will provide more insights into additional mechanisms of action of natalizumab and possibly allow better prediction of adverse events.

Multiple sclerosis as a generalized CNS disease—comparative microarray analysis of normal appearing white matter and lesions in secondary progressive MS

We used microarrays to compare the gene expression profile in active lesions and donor-matched normal appearing white matter (NAWM) from brain autopsy samples of patients with secondary progressive multiple sclerosis (MS) with that from controls who died from non-neurological diseases. The 123 genes in lesions, and 47 genes in NAWM(MS) were differentially expressed. Lesions distinguished from NAWM(MS) by a higher expression of genes related to immunoglobulin synthesis and neuroglial differentiation, while cellular immune response elements were equally dysregulated in both tissue compartments. Current results provide molecular evidence of a continuum of dysfunctional homeostasis and inflammatory changes between lesions and NAWM(MS), and support the concept of MS pathogenesis being a generalised process that involves the entire CNS.

Altered microRNA expression in B lymphocytes in multiple sclerosis: Towards a better understanding of treatment effects

MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression. We compared the expression of 1059 miRNAs in B lymphocytes from untreated and natalizumab treated relapsing-remitting multiple sclerosis (RRMS) patients and healthy volunteers (HV). Forty nine miRNAs were down-regulated in untreated MS patients compared with HV. A distinct pattern of 10 differentially expressed miRNAs was found in natalizumab treated patients compared with untreated patients. Two clusters, i.e. miR-106b-25 and miR-17-92, were particularly deregulated. MiRNA-mRNA interaction analysis revealed B cell receptor, phosphatidyl-inositol-3-kinase (PI3K) and phosphatase and tensin homology (PTEN) signaling being the key affected pathways. We discovered deregulated viral miRNAs in untreated patients as compared with HV and natalizumab treated patients, a novel finding that may be related to latency and activation of viruses in MS. Our findings provide first insights into miRNA dependent regulation of B cell function in MS and the impact of a therapy not primarily targeting B cells on this regulation.

Antimyelin antibodies in clinically isolated syndromes correlate with inflammation in MRI and CSF

ObjectiveWe investigated the correlation of anti-myelin oligodendrocyte glycoprotein- (anti-MOG) and anti-myelin basic protein antibodies (anti-MBP) in serum of CIS patients with inflammatory signs in MRI and in CSF and, as previously suggested, the incidence of more frequent and rapid progression to clinically definite MS (CDMS).Methods133 CIS patients were analysed for anti-MOG and anti-MBP (Western blot). Routine CSF and cranial MRI (quantitatively and qualitatively) measures were analyzed. 55 patients had a follow-up of at least 12 months or until conversion to CDMS.ResultsPatients with anti-MOG and anti-MBP had an increased intrathecal IgG production and CSF white blood cell count (p = 0.048 and p = 0.036). When anti-MBP alone, or both antibodies were present the cranial MRI showed significantly more T2 lesions (p = 0.007 and p = 0.01, respectively). There was a trend for more lesion dissemination in anti-MBP positive patients (p = 0.076). Conversely, anti-MOG- and/or anti-MBP failed to predict conversion to CDMS in our follow-up group (n = 55). Only in female patients with at least one MRI lesion (n = 34) did the presence of anti-MOG correlate with more frequent (p = 0.028) and more rapid (p = 0.0209) transition to CDMS.ConclusionsPresence of anti-MOG or anti-MBP or both was not significantly associated with conversion to CDMS in our CIS cohort. However, patients with anti-MOG and anti-MBP had higher lesion load and more disseminated lesions in cranial MRI as well as higher values for CSF leucocytes and intrathecal IgG production. Our data support a correlation of anti-MOG and anti-MBP to inflammatory signs in MRI and CSF. The prognostic value of these antibodies for CDMS, however, seems to be less pronounced than previously reported.

Unraveling natalizumab effects on deregulated miR-17 expression in CD4+ T cells of patients with relapsing-remitting multiple sclerosis.

MicroRNAs (miRNAs) are a family of noncoding RNAs that play critical roles in the posttranscriptional regulation of gene expression. Accumulating evidence supports their involvement in the pathogenesis of multiple sclerosis (MS). Here, we compare miR-17 expressions in CD4+ T cells from relapsing-remitting (RR) MS patients treated with natalizumab versus untreated patients. miR-17 was downregulated under natalizumab treatment and upregulated during relapse, therefore supporting a possible role of miR-17 in MS immunopathogenesis. Downregulation of miR-17 was associated with upregulation of PTEN, BIM, E2F1, and p21 target genes. In vitro miR-17 inhibition was associated with upregulation of the same targets and resulted in impaired CD4+ T cell activation and proliferation. We further describe deregulated TGFBR2 expression in untreated patients versus healthy volunteers (HVs) and confirm in vitro the link between miR-17 and TGFBR2 expressions. These findings support an effect of natalizumab on expression of specific miRNA and subsequent expression of genes involved in proliferation and control of the cell cycle.

MiR-126: a novel route for natalizumab action?

Background: MicroRNAs (miRNAs) have emerged as a family of post-transcriptional regulators of gene expression that mediate diverse aspects of immunity. MiRNA dysregulation has been found in multiple sclerosis (MS), reflecting the growing need to identify disease-specific miRNA expression signatures. Our previous low-density array studies reveal differential miR-126 expression in the CD4+T cells of untreated relapsing–remitting MS (RRMS) patients. Here, we investigated miR-126 expression in natalizumab-treated patients. Methods: We isolated CD4+ T cells from untreated (n = 12) and natalizumab-treated MS patients (n = 24), and from healthy volunteers (n = 12). We analyzed the expression of miRNAs and potential targets by real time reverse transcription polymerase chain reaction (RT-PCR). We assessed specific inhibition of miR-126, in vitro. Results: MiR-126 was down-regulated in cells of patients under natalizumab treatment and up-regulated during relapse, supporting a regulatory role in MS immunopathogenesis. MiR-126 expression correlated with the expression of POU2AF1, a regulator of Spi-B that binds to the promoter/enhancer sequences of JC virus (JCV), the pathogen of progressive multifocal leukoencephalopathy (PML), a rare complication of natalizumab treatment. The same trend was found for Spi-B. Strong up-regulation of both genes appeared to be treatment duration-dependent. Specific inhibition experiments supported the link between the expression of miR-126 and POU2AF1/Spi-B. Conclusions: Our findings provided deeper insight into the mode of action of natalizumab, with possible implications for understanding both the effects of natalizumab on MS activity and its specific adverse event profile.

Cytosolic persistence of mouse brain CYP1A1 in chronic heme deficiency.

Abstract Previous work has demonstrated that the function of extrahepatic cytochrome P450 CYP1A1 is dependent on the availability of heme. CYP1A1 is involved in the activation of polyaromatic hydrocarbons. In the present study we used a transgenic mouse model with chronic impairment of heme synthesis – female porphobilinogen deaminase-deficient (PBGD-/-) mice – to investigate the effects of limited heme in untreated and β-naphthoflavone (β-NF)-treated animals on the function of CYP1A1 in brain. The heme content of PBGD-/- mice was diminished in the liver and brain compared to wild types. In the liver, partial heme deficiency led to less potent induction of CYP1A1 mRNA after β-NF treatment. In the brain, CYP1A1 protein was detected not only at the endoplasmic reticulum (ER), but also in the cytosol of PBGD-/- mice. Furthermore, 7-deethylation of ethoxyresorufin, an indicator of CYP1A1 metabolic activity, could be restored by heme in cytosol of PBGD-/- mouse brain. Independent of the genotype, we found only one cyp1a1 gene product, indicating that the cytosolic appearance of CYP1A1 most likely did not originate from mutant alleles. We conclude that heme deficiency in the brain leads to incomplete heme saturation of CYP1A1, which causes its improper incorporation into the ER membrane and persistence in the cytosol. It is suggested that diseases caused by relative heme deficiency, such as hepatic porphyrias, may lead to impaired hemoprotein function in brain.

Qualitative and quantitative analysis of antibody response against IFNβ in patients with multiple sclerosis

To date, inter-and intra-laboratory consistency of binding assays for measuring anti-interferon (IFN)β antibodies has not been assessed. In this investigation, two independent laboratories tested a library of 80 serum specimens obtained from multiple sclerosis (MS) patients treated with IFNβ. For binding antibodies (BAbs) evaluations, each laboratory used both a capture-ELISA (cELISA) and an enzyme-immuno-assay (EIA), which is commercially available. Samples were also tested for neutralizing antibodies (NAbs). Data demonstrated good intra-laboratory reliability (rpearson≥0.86), and a good overall agreement between the results obtained from the two centers, using both the cELISA (69/80 of observed agreements) and the EIA (67/80). Accordingly, kappa coefficients (K) showed good concurrence (K ≥ 0.651). There was also substantial agreement between cELISA and EIA measurements, as performed in both centers (Orbassano, 66/80, K = 0.631; Basel, 70/80, K = 0.717). However, by comparing NAbs and BAbs titers obtained with both assays, we found that a high degree of BAb-negative samples were positive in NAb-assay. Thus, our study does not support the usefulness of ELISA-based BAb assays as a screening tool for NAbs. Otherwise, BAb-assays can be used as a confirmation test, indicating that the decrease of the biological effects is due to antibodies. In this context, both ELISA-based assays are equally reliable techniques.

Natalizumab-induced POU2AF1/Spi-B upregulation: A possible route for PML development

Objectives: To assess messenger RNA (mRNA) expression of POU2AF1 and Spi-B and their potential regulatory microRNAs (miRNAs) in natalizumab-treated patients with multiple sclerosis and in therapy-associated progressive multifocal leukoencephalopathy (PML). Methods: Expression of POU2AF1/Spi-B was analyzed by using real-time reverse transcription PCR assays on isolated B/CD8+ T lymphocytes and peripheral blood mononuclear cells (PBMCs) from cohorts of untreated and natalizumab-treated patients with and without PML. Longitudinal expression analysis was performed on CD4+, CD8+ T and B cells from 14 patients who interrupted natalizumab therapy for 8 weeks. The miRNA profiling was conducted in PBMCs from 5 untreated and 5 natalizumab-treated patients using low-density arrays followed by validation with single miRNAs assays in untreated and natalizumab-treated patients. Results: POU2AF1 and Spi-B mRNAs were upregulated in B and CD8+ T cells from natalizumab-treated patients, which was validated in PBMCs from different cohorts of natalizumab-treated patients with and without PML, with a noteworthy higher expression of Spi-B in patients with PML. In contrast, downregulation of POU2AF1/Spi-B expression was measured in B and CD8+ T cells after natalizumab discontinuation. Seventeen differentially expressed miRNAs including miR-10b, a regulator of POU2AF1 mRNA, were identified in long-term natalizumab-treated patients compared with untreated ones. Conclusions: Upregulation of POU2AF1 and Spi-B, known transactivators of the JC virus, the causative agent for PML, and its association with occurrence of PML in natalizumab-treated patients, corroborates POU2AF1/Spi-B as potential biomarkers for PML risk, which merits further evaluation.