Antonios Bayas

Characteristic gene expression profile of primary human cerebral endothelial cells

Endothelial cells of blood vessels forming the interphase between systemic circulation and tissues are crucial for maintenance of homeostasis and organ‐related functions. Recent experiments support organ‐specific endothelial differentiation and suggest differential gene expression patterns in endothelial cells. Here, we compared gene expression in primary human cerebral endothelial cells (HCEC), which are major constituents of the blood brain barrier (BBB), with human umbilical vein endothelial cells (HUVEC) by using cDNA array analysis of 375 genes. Under basal culture conditions, 35 genes were expressed only in HCEC, whereas 20 gene transcripts were detected only in HUVEC. A total of 78 genes were expressed in both endothelial cell types partly with distinct expression levels. Genes expressed by cerebral endothelial cells are important in vasculo‐ and angiogenesis (VEGF, erbB1) and immunoregulation (OSM‐Rβ, decorin, IL‐6) or have growth‐supporting properties (brain‐derived neurotrophic factor, stem cell factor, transforming growth factor‐β). The differential gene expression profiles were confirmed at the protein level of cell cultures (ELISA, immunoblotting) and human tissues (immunohistochemistry). Identification and further functional characterization of genes specifically expressed by cerebral endothelial cells will have important impact on our understanding of endothelial function at the BBB.

Natalizumab Therapy for Highly Active Pediatric Multiple Sclerosis

IMPORTANCE Given the high frequency of failure of first-line therapies, there is an urgent need for second-line treatment strategies for pediatric patients with multiple sclerosis (MS). OBJECTIVE To report the use of natalizumab in pediatric MS. Natalizumab, a humanized monoclonal antibody targeting α4 integrin, is effective against active relapsing-remitting MS in adults. DESIGN Retrospective study. SETTING Eleven centers for neurology and pediatric neurology in Germany and Austria. PARTICIPANTS A total of 20 pediatric patients with MS who started treatment with natalizumab prior to 18 years of age. These patients underwent magnetic resonance imaging as clinically indicated, despite the fact that 19 of these 20 patients were undergoing first-line disease-modifying therapy. The mean (SD) age at initiation of natalizumab therapy was 16.7 (1.1) years, and the mean (SD) pretreatment period was 18 (10) months. INTERVENTION Natalizumab, 300 mg every 4 weeks. MAIN OUTCOME MEASURES Annualized relapse rates, Expanded Disability Status Scale scores, number of new T2/fluid-attenuated inversion recovery lesions and contrast-enhancing lesions on magnetic resonance imaging, number of adverse events, the prevalence of neutralizing antibodies against natalizumab, and serum JC virus-antibody status. RESULTS Treatment with natalizumab was associated with reductions in mean annualized relapse rates (3.7 without treatment vs 0.4 with treatment; P < .001), median Expanded Disability Status Scale scores (2 without treatment vs 1 with treatment; P < .02), and mean number of new T2/fluid-attenuated inversion recovery lesions per year (7.8 without treatment vs 0.5 with treatment; P < .001). Two patients developed high-titer neutralizing antibodies against natalizumab and had to stop therapy. Adverse events included headaches, asthenia, infections, and hypersensitivity. Abnormal laboratory results were found for 8 patients. JC virus antibodies were found in 5 of 13 patients. After the discontinuation of natalizumab therapy, relapse activity occurred in 6 of 8 patients within 6 months. CONCLUSIONS AND RELEVANCE Our data indicate that natalizumab may be safe and effective against MS in pediatric patients with breakthrough disease.

Listeria Meningitis Complicating Alemtuzumab Treatment in Multiple Sclerosis—Report of Two Cases

Alemtuzumab, a humanized monoclonal antibody targeting the surface molecule CD52, leads to a rapid depletion of immune cells in the innate and adaptive immune system. In phase 2 and 3 trials in multiple sclerosis (MS), infections have been reported more frequently in alemtuzumab than in interferon beta treated patients. Here we report two patients treated with alemtuzumab for MS developing Listeria meningitis few days after the first infusion cycle. Both patients recovered completely after prompt diagnosis and adequate treatment. Physicians and patients should be aware of this serious, but treatable complication.

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation.

Genome-wide study in Germans identifies four novel multiple sclerosis risk genes and confirms already known gene loci. We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis.

Accidental natalizumab administration to the third trimester of pregnancy in an adolescent patient with multiple sclerosis

Bayas A, Penzien J, Hellwig K. Accidental natalizumab administration to the third trimester of pregnancy in an adolescent patient with multiple sclerosis.
Acta Neurol Scand: 2011: 124: 290–292.
© 2011 John Wiley & Sons A/S.

Long-term treatment of Lewis-Sumner syndrome with subcutaneous immunoglobulin infusions.

Lewis-Sumner syndrome (LSS, synonymous multifocal acquired demyelinating sensory and motor neuropathy, MADSAM) is a dysimmune peripheral neuropathy responding to corticosteroids and intravenous immunoglobulins (IVIG) in the majority of patients. We report on the long term treatment (37 and 46months respectively) of two LSS patients, who had initially responded to IVIG, with subcutaneous immunoglobulins (SCIg). Both were switched to SCIg since stabilization by IVIG could only be achieved with short treatment intervals, and one of them also suffered from recurrent transient ischemic attacks (TIAs) following IVIG related increased blood viscosity. Long-term use of SCIg was safe and well tolerated. Both patients were clinically stable with only mild to moderate fluctuations requiring SCIg dosage adaptions. No further ischemic events occurred, when the patient was switched to SCIg.

Adherence to, and effectiveness of, subcutaneous interferon β-1a administered by RebiSmart® in patients with relapsing multiple sclerosis: results of the 1-year, observational SMART study

Background: Patients with multiple sclerosis who have poor adherence to treatment have a higher risk of relapse than adherent patients. This study assessed adherence to, and effectiveness and convenience of, treatment with subcutaneous (sc) interferon (IFN) β-1a (Rebif®, Merck Serono SA) 44 or 22 μg three times weekly in patients with relapsing multiple sclerosis (RMS) using the RebiSmart® electronic, multidose, autoinjector for 1 year. Study design: European, multicentre, observational study among neurologists: inclusion criteria included RMS, Expanded Disability Status Scale score ≤ 6, sc IFN β-1a administered by RebiSmart for ≤ 6 weeks. The primary endpoint was cumulative adherence recorded by RebiSmart. Results: The safety population included 912 patients, 77.4% (n = 823) of whom completed the Month-12 visit. Mean (± standard deviation) cumulative adherence was 97.1 ± 7.3% (n = 791). The most common reason for missed injection was ‘forgot to inject’ (37.0%). At Month 12/ED, 79.5% of patients were relapse-free. Of 353 patients who rated the convenience of the device, 68.3% found injecting ‘very easy’. No unknown safety issues were detected. Conclusions: Patients with RMS self-injecting sc IFN β-1a with RebiSmart had excellent adherence at Month 12/ED, which was associated with good clinical outcomes and no unexpected safety issues. Patients rated RebiSmart as convenient and easy to use.

Successful Replication of GWAS Hits for Multiple Sclerosis in 10,000 Germans Using the Exome Array.

Genome‐wide association studies (GWAS) successfully identified various chromosomal regions to be associated with multiple sclerosis (MS). The primary aim of this study was to replicate reported associations from GWAS using an exome array in a large German study. German MS cases (n = 4,476) and German controls (n = 5,714) were genotyped using the Illumina HumanExome v1‐Chip. Genotype calling was performed with the Illumina Genome StudioTM Genotyping Module, followed by zCall. Single‐nucleotide polymorphisms (SNPs) in seven regions outside the human leukocyte antigen (HLA) region showed genome‐wide significant associations with MS (P values < 5 × 10−8). These associations have been reported previously. In addition, SNPs in three previously reported regions outside the HLA region yielded P values < 10−5. The effect of nine SNPs in the HLA region remained (P < 10−5) after adjustment for other significant SNPs in the HLA region. All of these findings have been reported before or are driven by known risk loci. In summary, findings from previous GWAS for MS could be successfully replicated. We conclude that the regions identified in previous GWAS are also associated in the German population. This reassures the need for detailed investigations of the functional mechanisms underlying the replicated associations.

The brain antigen-specific B cell response correlates with glatiramer acetate responsiveness in relapsing-remitting multiple sclerosis patients

B cells have only recently begun to attract attention in the immunopathology of multiple sclerosis (MS). Suitable markers for the prediction of treatment success with immunomodulatory drugs are still missing. Here we evaluated the B cell response to brain antigens in n = 34 relapsing-remitting MS (RRMS) patients treated with glatiramer acetate (GA) using the enzyme-linked immunospot technique (ELISPOT). Our data demonstrate that patients can be subdivided into responders that show brain-specific B cell reactivity in the blood and patients without this reactivity. Only in patients that classified as B cell responders, there was a significant positive correlation between treatment duration and the time since last relapse in our study. This correlation was GA-specific because it was absent in a control group that consisted of interferon-ß (IFN-β)-treated RRMS patients (n = 23). These data suggest that GA has an effect on brain-reactive B cells in a subset of patients and that only this subset benefits from treatment. The detection of brain-reactive B cells is likely to be a suitable tool to identify drug responders.

The Correlation between the Virus- and Brain Antigen-Specific B Cell Response in the Blood of Patients with Multiple Sclerosis

There is a largely divergent body of literature regarding the relationship between Epstein-Barr virus (EBV) infection and brain inflammation in multiple sclerosis (MS). Here, we tested MS patients during relapse (n = 11) and in remission (n = 19) in addition to n = 22 healthy controls to study the correlation between the EBV- and brain-specific B cell response in the blood by enzyme-linked immunospot (ELISPOT) and enzyme-linked immunosorbent assay (ELISA). Cytomegalovirus (CMV) was used as a control antigen tested in n = 16 MS patients during relapse and in n = 35 patients in remission. Over the course of the study, n = 16 patients were untreated, while n = 33 patients received immunomodulatory therapy. The data show that there was a moderate correlation between the frequencies of EBV- and brain-reactive B cells in MS patients in remission. In addition we could detect a correlation between the B cell response to EBV and disease activity. There was no evidence of an EBV reactivation. Interestingly, there was also a correlation between the frequencies of CMV- and brain-specific B cells in MS patients experiencing an acute relapse and an elevated B cell response to CMV was associated with higher disease activity. The trend remained when excluding seronegative subjects but was non-significant. These data underline that viral infections might impact the immunopathology of MS, but the exact link between the two entities remains subject of controversy.