Kappa free light chains is a valid tool in the diagnostics of MS: A large multicenter study.

OBJECTIVE: To validate kappa free light chain (KFLC) and lambda free light chain (LFLC) indices as a diagnostic biomarker in multiple sclerosis (MS). METHODS: We performed a multicenter study including 745 patients from 18 centers (219 controls and 526 clinically isolated syndrome (CIS)/MS patients) with a known oligoclonal IgG band (OCB) status. KFLC and LFLC were measured in paired cerebrospinal fluid (CSF) and serum samples. Gaussian mixture modeling was used to define a cut-off for KFLC and LFLC indexes. RESULTS: The cut-off for the KFLC index was 6.6 (95% confidence interval (CI) = 5.2-138.1). The cut-off for the LFLC index was 6.9 (95% CI = 4.5-22.2). For CIS/MS patients, sensitivity of the KFLC index (0.88; 95% CI = 0.85-0.90) was higher than OCB (0.82; 95%CI = 0.79-0.85; p < 0.001), but specificity (0.83; 95% CI = 0.78-0.88) was lower (OCB = 0.92; 95% CI = 0.89-0.96; p < 0.001). Both sensitivity and specificity for the LFLC index were lower than OCB. CONCLUSION: Compared with OCB, the KFLC index is more sensitive but less specific for diagnosing CIS/MS. Lacking an elevated KFLC index is more powerful for excluding MS compared with OCB but the latter is more important for ruling in a diagnosis of CIS/MS.

John Cunningham virus conversion in relation to natalizumab concentration in multiple sclerosis patients.

BACKGROUND AND PURPOSE: Infection with the John Cunningham virus (JCV) is required for the development of progressive multifocal leukoencephalopathy, the feared complication of natalizumab treatment in multiple sclerosis patients. The JCV seroconversion rate seems higher in natalizumab treated patients than in the normal population, with an unknown cause. METHODS: Natalizumab concentration was correlated to JCV antibody status and seroconversion in a large cohort of multiple sclerosis patients. RESULTS: One hundred and thirty-five patients were included. No correlation was found between natalizumab concentration and JCV status, JCV seroconversion or JCV index. CONCLUSIONS: Higher natalizumab concentrations do not explain the increased JCV seroconversion rate in natalizumab treated patients.

High cumulative JC virus seroconversion rate during long-term use of natalizumab.

BACKGROUND AND PURPOSE: John Cunningham virus (JCV) seropositivity is a risk factor for the development of natalizumab-associated progressive multifocal leukoencephalopathy (PML) in multiple sclerosis (MS) patients. When JCV seronegative patients seroconvert, their risk of developing PML increases. Limited longitudinal data exist about the seroconversion rate amongst natalizumab-treated relapsing-remitting MS (RRMS) patients. Our objective was to evaluate the seroconversion rate in a large Dutch cohort of natalizumab-treated RRMS patients. Seroconversion was defined as at least two consecutive seropositive serum samples (or cessation of therapy after a single seropositive sample because of seropositivity) after initial seronegative testing. METHODS AND RESULTS: In our study of 179 patients for whom longitudinal blood samples were available over a long period (median 4.2 years), anti-JCV antibody indices were measured in 933 available samples. Eighty-six patients (48.0%) tested seronegative initially. Of these 86 seronegative patients, 23 patients (26.7%) seroconverted during follow-up. The annualized seroconversion rate was 7.1%. Seroconversion occurred between 9 and 90 months (median 43 months) of treatment. The rate of seroconversion was independent of follow-up duration. No significant increase was seen in the anti-JCV antibody index in the non-converting patients during the follow-up. CONCLUSION: The annualized seroconversion rate of 7.1% in patients using natalizumab, cumulatively leading to more than 25% of seronegative patients becoming seropositive in 4 years, is of clinical relevance and should be taken into account in the risk assessment when considering the start of natalizumab therapy.

Acid sphingomyelinase: No potential as a biomarker for multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) lacks reliable biomarkers that reflect disease activity. Recent evidence suggests that an altered sphingolipid metabolism is associated with MS pathogenesis. OBJECTIVE: To explore acid sphingomyelinase (ASM) activity and altered sphingolipid metabolism as potential biomarkers in serum of MS patients, to predict active and progressive disease, and response to disease modifying therapy (DMT). METHODS: Levels of serum ASM activity were longitudinally analyzed in 40 clinically isolated syndrome, 64 relapsing remitting (RR) and 10 primary progressive MS patients, and 22 healthy controls (HC). ASM activity and sphingolipid levels were measured in a different sample of 61 RRMS patients using DMT. RESULTS: A significant difference in ASM activity levels was observed between MS patients and HC (p < 0.001). There was no correlation between ASM activity levels and disease activity, progression or response to DMT. Ceramide (Cer)-C16:0 , Cer-C24:0 and sphingomyelin (SM)-C20:0, SM-C22:0, SM-C24:0 and SM-C24:1 showed a significant increase during fingolimod use. CONCLUSION: Although higher levels in MS patients were found, ASM activity levels do not show potential as a biomarker for predicting disease activity, progression or response to DMT. Two ceramides and four types of sphingomyelin require further investigation as potential markers for treatment response.

Long-term disease activity and disability progression in relapsing-remitting multiple sclerosis patients on natalizumab.

BACKGROUND: Natalizumab is an effective treatment for relapsing-remitting multiple sclerosis (RRMS). Data on clinical and imaging measures predictive of disease activity and progression during treatment is limited. OBJECTIVE: To determine clinical and imaging predictors of long-term inflammatory disease activity and disability progression in RRMS patients on natalizumab. METHODS: Patients (n = 135) were selected from our prospective observational natalizumab cohort and monitored using brain MRI and extensive clinical testing. Progression and improvement on the Expanded Disability Status Scale (EDSS), no evidence of disease activity (NEDA) and no evidence of progression or active disease (NEPAD) status were determined using measurements after the initial phase of inflammation and the early anti-inflammatory impact of natalizumab. RESULTS: EDSS progression was seen in 43.7% of patients and EDSS improvement in 17.8%. Median follow-up was 4.9 years (IQR 3.6-6.0). Patients with a longer disease duration at natalizumab initiation have a higher hazard for earlier EDSS progression (HR 1.05, CI 1.00-1.09, p = 0.037) and a higher pre-baseline relapse rate predicted a longer NEPAD status (HR 1.70, CI 1.06-2.72, p = 0.028). CONCLUSION: The results suggest that starting natalizumab early, during active inflammatory disease results in a more favourable outcome. When taking into account early inflammation and the impact of natalizumab on disease activity during the initial treatment phase, a higher than expected proportion of patients showed disability progression.

Information processing speed in multiple sclerosis: Relevance of default mode network dynamics.

Objective: To explore the added value of dynamic functional connectivity (dFC) of the default mode network (DMN) during resting-state (RS), during an information processing speed (IPS) task, and the within-subject difference between these conditions, on top of conventional brain measures in explaining IPS in people with multiple sclerosis (pwMS). Methods: In 29 pwMS and 18 healthy controls, IPS was assessed with the Letter Digit Substitution Test and Stroop Card I and combined into an IPS-composite score. White matter (WM), grey matter (GM) and lesion volume were measured using 3 T MRI. WM integrity was assessed with diffusion tensor imaging. During RS and task-state fMRI (i.e. symbol digit modalities task, IPS), stationary functional connectivity (sFC; average connectivity over the entire time series) and dFC (variation in connectivity using a sliding window approach) of the DMN was calculated, as well as the difference between both conditions (i.e. task-state minus RS; ΔsFC-DMN and ΔdFC-DMN). Regression analysis was performed to determine the most important predictors for IPS. Results: Compared to controls, pwMS performed worse on IPS-composite (p = 0.022), had lower GM volume (p < 0.05) and WM integrity (p < 0.001), but no alterations in sFC and dFC at the group level. In pwMS, 52% of variance in IPS-composite could be predicted by cortical volume (ß = 0.49, p = 0.01) and ΔdFC-DMN (ß = 0.52, p < 0.01). After adding dFC of the DMN to the model, the explained variance in IPS increased with 26% (p < 0.01). Conclusion: On top of conventional brain measures, dFC from RS to task-state explains additional variance in IPS. This highlights the potential importance of the DMN to adapt upon cognitive demands to maintain intact IPS in pwMS.

Selection of novel mediators of E2F1-induced apoptosis through retroviral expression of an antisense cDNA library.

The E2F1 transcription factor is an essential mediator of p53-dependent and p53-independent apoptosis as part of an anti-tumour safeguard mechanism. In this study, a functional so-called technical knockout (TKO) approach was applied to Saos-2ERE2F1 cells that conditionally activate E2F1 by the addition of 4-hydroxytamoxifen to search for p53-independent pro-apoptotic E2F1 targets. The approach was based on random inactivation of genes after retroviral transfer of an antisense cDNA library enriched of E2F1-induced genes, followed by the selection of Saos-2ERE2F1 cells that survive in the presence of the apoptotic stimulus. We identified 13 novel E2F1 target genes encoding proteins of known cellular function, including apoptosis and RNA binding. FACS analysis revealed that E2F1-induced apoptosis was significantly attenuated in cell clones containing the antisense cDNA fragments of these genes, demonstrating their participation in E2F1 death pathways. Moreover, inactivation of the target genes resulted in a clear increase of cell viability (>80%) in response to E2F1 activation compared with controls (approximately 30%). Four genes showed an increase in expression intensity in the presence of cycloheximide, suggesting a direct effect of E2F1 on gene transcription, whereas one gene was identified as an indirect target. Our data provide new insight in the regulation of E2F1-induced apoptosis.

The sequence complementarity between HIV-1 5' splice site SD4 and U1 snRNA determines the steady-state level of an unstable env pre-mRNA.

HIV-1 env expression from certain subgenomic vectors requires the viral regulatory protein Rev, its target sequence RRE, and a 5' splice site upstream of the env open reading frame. To determine the role of this splice site in the 5'-splice-site-dependent Rev-mediated env gene expression, we have subjected the HIV-1 5' splice site, SD4, to a mutational analysis and have analyzed the effect of those mutations on env expression. The results demonstrate that the overall strength of hydrogen bonding between the 5' splice site, SD4, and the free 5' end of the U1 snRNA correlates with env expression efficiency, as long as env expression is suboptimal, and that a continuous stretch of 14 hydrogen bonds can lead to full env expression, as a result of stabilizing the pre-mRNA. The U1 snRNA-mediated stabilization is independent of functional splicing, as a mismatch in position +1 of the 5' splice site that led to loss of detectable amounts of spliced transcripts did not preclude stabilization and expression of the unspliced env mRNA, provided that Rev enables its nuclear export. The nucleotides capable of participating in U1 snRNA:pre-mRNA interaction include positions -3 to +8 of the 5' splice site and all 11 nt constituting the single-stranded 5' end of U1 snRNA. Moreover, env gene expression is significantly decreased upon the introduction of point mutations in several upstream GAR nucleotide motifs, which are mediating SF2/ASF responsiveness in an in vitro splicing assay. This suggests that the GAR sequences may play a role in stabilizing the pre-mRNA by sequestering U1 snRNP to SD4.