Early Alzheimer's Disease Screening Approach Using Plasma Biomarkers.

Alzheimer's disease (AD) is the most prevalent dementia, but it shows similar initial symptoms to other neurocognitive diseases (Lewy body disease (LBD) and frontotemporal dementia (FTD)). Thus, the identification of reliable AD plasma biomarkers is required. The aim of this work is to evaluate the use of a few plasma biomarkers to develop an early and specific AD screening method. Plasma p-Tau181, neurofilament light (NfL), and glial fibrillary acid protein (GFAP) were determined by Single Molecule Assay (SIMOA® Quanterix, Billerica, MA, USA) in patients with mild cognitive impairment due to AD (MCI-AD, n = 50), AD dementia (n = 10), FTD (n = 20), LBD (n = 5), and subjective cognitive impairment (SCI (n = 21)). Plasma p-Tau181 and GFAP showed the highest levels in AD dementia, and significant correlations with clinical AD characteristics; meanwhile, NfL showed the highest levels in FTD, but no significant correlations with AD. The partial least squares (PLS) diagnosis model developed between the AD and SCI groups showed good accuracy with a receiver operating characteristic (ROC) area under curve (AUC) of 0.935 (CI 95% 0.87-0.98), sensitivity of 86%, and specificity of 88%. In a first screen, NfL plasma levels could identify FTD patients among subjects with cognitive impairment. Then, the developed PLS model including p-Tau181 and GFAP levels could identify AD patients, constituting a simple, early, and specific diagnosis approach.

Expression of the H2O2 Biosensor roGFP-Tpx1.C160S in Fission and Budding Yeasts and Jurkat Cells to Compare Intracellular H2O2 Levels, Transmembrane Gradients, and Response to Metals.

Intracellular hydrogen peroxide (H2O2) levels can oscillate from low, physiological concentrations, to intermediate, signaling ones, and can participate in toxic reactions when overcoming certain thresholds. Fluorescent protein-based reporters to measure intracellular H2O2 have been developed in recent decades. In particular, the redox-sensitive green fluorescent protein (roGFP)-based proteins fused to peroxiredoxins are among the most sensitive H2O2 biosensors. Using fission yeast as a model system, we recently demonstrated that the gradient of extracellular-to-intracellular peroxides through the plasma membrane is around 300:1, and that the concentration of physiological H2O2 is in the low nanomolar range. Here, we have expressed the very sensitive probe roGFP2-Tpx1.C169S in two other model systems, budding yeast and human Jurkat cells. As in fission yeast, the biosensor is ~40-50% oxidized in these cell types, suggesting similar peroxide steady-state levels. Furthermore, probe oxidation upon the addition of extracellular peroxides is also quantitatively similar, suggesting comparable plasma membrane H2O2 gradients. Finally, as a proof of concept, we have applied different concentrations of zinc to all three model systems and have detected probe oxidation, demonstrating that an excess of this metal can cause fluctuations of peroxides, which are moderate in yeasts and severe in mammalian cells. We conclude that the principles governing H2O2 fluxes are very similar in different model organisms.

Perturbed fatty-acid metabolism is linked to localized chromatin hyperacetylation, increased stress-response gene expression and resistance to oxidative stress.

Oxidative stress is associated with cardiovascular and neurodegenerative diseases, diabetes, cancer, psychiatric disorders and aging. In order to counteract, eliminate and/or adapt to the sources of stress, cells possess elaborate stress-response mechanisms, which also operate at the level of regulating transcription. Interestingly, it is becoming apparent that the metabolic state of the cell and certain metabolites can directly control the epigenetic information and gene expression. In the fission yeast Schizosaccharomyces pombe, the conserved Sty1 stress-activated protein kinase cascade is the main pathway responding to most types of stresses, and regulates the transcription of hundreds of genes via the Atf1 transcription factor. Here we report that fission yeast cells defective in fatty acid synthesis (cbf11, mga2 and ACC/cut6 mutants; FAS inhibition) show increased expression of a subset of stress-response genes. This altered gene expression depends on Sty1-Atf1, the Pap1 transcription factor, and the Gcn5 and Mst1 histone acetyltransferases, is associated with increased acetylation of histone H3 at lysine 9 in the corresponding gene promoters, and results in increased cellular resistance to oxidative stress. We propose that changes in lipid metabolism can regulate the chromatin and transcription of specific stress-response genes, which in turn might help cells to maintain redox homeostasis.

Oligoclonal M bands and cervical spinal cord lesions predict early secondary progressive multiple sclerosis.

Objective: To determine baseline cerebrospinal fluid and magnetic resonance imaging (MRI) variables at the onset of a clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS) that predict evolution to secondary progressive MS (SPMS). Methods: 276 CIS patients with a minimum follow-up of 10 years were studied. Baseline presence of oligoclonal IgG and IgM bands (OCGB and OCMB respectively); number of brain T2 lesions (B-T2L), brain gadolinium enhancement lesions (brain-GEL), cervical spinal cord T2 lesions (cSC-T2L); and fulfillment of 2017 McDonald criteria among other variables were collected. Results: 14 patients ended up with a non-MS condition. 138/276 CIS patients fulfilled 2017 McDonald criteria. Mean age was 32.4 years, 185 female. 227 received treatment, 95 as CIS. After a mean follow-up of 12 years, 36 patients developed SPMS. Conversion to SPMS was associated with OCGB (p = 0.02), OCMB (p = 0.0001); ≥ 9 B-T2L (p = 0.03), brain-GEL (p = 0.03), and cSC-T2L (p = 0.03). However, after adjusting for sex, age, BT2L, brain-GEL, SC-T2, and OCMB status, only OCMB (HR 4.4, 1.9-10.6) and cSC-T2L (HR 2.2, 1.0-6.2) suggested an independent association with risk of conversion to SPMS. Patients with both risk factors had a HR of 6.12 (2.8-12.9). Discussion: OCMB and SC-T2 lesions are potential independent predictors of conversion to SPMS.

Oligoclonal M bands unveil occult inflammation in multiple sclerosis.

INTRODUCTION: Recent works demonstrate that patients with multiple sclerosis (pwMS) and oligoclonal M bands (OCMB) in cerebrospinal fluid (CSF) are at higher risk of conversion to secondary progressive course, suggesting a distinct pathophysiology pathway in these patients. OBJECTIVES: To analyze the relationship of serum neurofilament light chain (s-NFL) in absence of inflammatory activity in people with multiple sclerosis (pwMS) according to the presence of OCMB versus healthy controls (HC), and the effect of aging. METHODS: Two cohorts of HC were compared to a cohort of pwMS without clinical or radiological signs of acute inflammation. Lack of inflammation was defined as the absence of relapses or gadolinium-enhancing lesions (GEL) brain in an MRI performed within three months before and after s-NFL determination. S-NFL was measured with SIMOa technology. OCMB in the cerebrospinal fluid (CSF) were analyzed with isoelectric focusing and immunoblotting. RESULTS: 254 people were studied: 124 healthy voluntary controls and 130 pwMS. Despite the absence of inflammatory activity, pwMS and OCMB showed higher levels of s-NFL compared to those without OCMB and HC (11.4 pg/mL, 8.9 pg/mL and 9.0 pg/mL, respectively). A positive and exponential correlation between age and s-NFL was observed, with highest increases among pwMS and OCMB in the CSF. DISCUSSION: In absence of overt inflammatory activity, pwMS and OCMB exhibit higher s-NFL levels, and a greater age-related increase. Thus, OCMB may portray an underlying inflammatory process not detected by conventional MRI studies and may explain the poorer prognosis of these patients.

Antagonistic effects of mitochondrial matrix and intermembrane space proteases on yeast aging.

BACKGROUND: In many organisms, aging is characterized by a loss of mitochondrial homeostasis. Multiple factors such as respiratory metabolism, mitochondrial fusion/fission, or mitophagy have been linked to cell longevity, but the exact impact of each one on the aging process is still unclear. RESULTS: Using the deletion mutant collection of the fission yeast Schizosaccharomyces pombe, we have developed a genome-wide screening for mutants with altered chronological lifespan. We have identified four mutants associated with proteolysis at the mitochondria that exhibit opposite effects on longevity. The analysis of the respiratory activity of these mutants revealed a positive correlation between increased respiration rate and prolonged lifespan. We also found that the phenotype of the long-lived protease mutants could not be explained by impaired mitochondrial fusion/fission activities, but it was dependent on mitophagy induction. The anti-aging role of mitophagy was supported by the effect of a mutant defective in degradation of mitochondria, which shortened lifespan of the long-lived mutants. CONCLUSIONS: Our characterization of the mitochondrial protease mutants demonstrates that mitophagy sustains the lifespan extension of long-lived mutants displaying a higher respiration potential.

Effectiveness of rituximab vs. ocrelizumab for the treatment of primary progressive multiple sclerosis: a real-world observational study.

INTRODUCTION: Ocrelizumab, an antiCD-20 antibody, is the only drug approved to treat patients with primary progressive multiple sclerosis (pwPPMS). Not all candidates receive this treatment due to prescription limitations. Rituximab, another antiCD-20 antibody, has been used off-label in pwPPMS before and after ocrelizumab approval. However, studies comparing effectiveness of both drugs are lacking. OBJECTIVE: To evaluate effectiveness of rituximab and ocrelizumab in pwPPMS under real-life conditions. METHODS: We conducted a multicentric observational study of pwPPMS that started ocrelizumab or rituximab according to clinical practice, with a minimum follow-up of 1 year. Data was collected prospectively and retrospectively. Primary outcome was time to confirmed disability progression at 3 months (CDW). Secondary outcome was serum neurofilament light chain levels (sNFL) at the end of follow-up. RESULTS: 95 out 111 pwPPMS fulfilled inclusion criteria and follow-up data availability: 49 (51.6%) received rituximab and 46 (48.4%) ocrelizumab. Rituximab-treated patients had significantly higher baseline EDSS, disease duration and history of previous disease-modifying treatment (DMT) than ocrelizumab-treated patients. After a mean follow-up of 18.3 months (SD 5.9), 26 patients experienced CDW (21.4%); 15 (30.6%) in the rituximab group; and 11 (23.9%) in the ocrelizumab group. Survival analysis revealed no differences in time to CDW. sNFL were measured in 60 patients and no differences between groups were found. INTERPRETATION: We provide real-world evidence of effectiveness of ocrelizumab and rituximab in pwPPMS. No differences in time to CDW were found between treatments. However, this study cannot establish equivalence of treatments and warrant clinical trial to confirm our findings.

The Mitochondria-to-Cytosol H2O2 Gradient Is Caused by Peroxiredoxin-Dependent Cytosolic Scavenging.

Fluorescent protein-based reporters used to measure intracellular H2O2 were developed to overcome the limitations of small permeable dyes. The two major families of genetically encoded redox reporters are the reduction-oxidation sensitive green fluorescent protein (roGFP)-based proteins fused to peroxiredoxins and HyPer and derivatives. We have used the most sensitive probes of each family, roGFP2-Tpx1.C169S and HyPer7, to monitor steady-state and fluctuating levels of peroxides in fission yeast. While both are able to monitor the nanomolar fluctuations of intracellular H2O2, the former is two-five times more sensitive than HyPer7, and roGFP2-Tpx1.C169S is partially oxidized in the cytosol of wild-type cells while HyPer7 is fully reduced. We have successfully expressed HyPer7 in the mitochondrial matrix, and it is ~40% oxidized, suggesting higher steady-state levels of peroxides, in the low micromolar range, than in the cytosol. Cytosolic HyPer7 can detect negligible H2O2 in the cytosol from mitochondrial origin unless the main H2O2 scavenger, the cytosolic peroxiredoxin Tpx1, is absent, while mitochondrial HyPer7 is oxidized to the same extent in wild-type and ∆tpx1 cells. We conclude that there is a bidirectional flux of H2O2 across the matrix and the cytosol, but Tpx1 rapidly and efficiently scavenges mitochondrial-generated peroxides and stops their steady-state cytosolic levels rising.

CSF chitinase 3-like-1 association with disability of primary progressive MS.

OBJECTIVE: To assess the role of CSF chitinase 3-like-1 (CHI3L1), chitinase 3-like-2 (CHI3L2), and neurofilament light chain (NfL) in predicting the course of primary progressive MS (PPMS). METHODS: We analyzed CSF CHI3L1, CHI3L2, and NfL levels in 25 patients with PPMS with disease duration ≤10 years and no disease-modifying therapy for ≥6 months from the prospective Understanding Primary Progressive Multiple Sclerosis cohort study. CSF samples taken at disease diagnosis were analyzed using commercial ELISAs and following the manufacturer's instructions. Data on Expanded Disability Status Scale (EDSS) scores, disability progression, and cognitive function according to the Brief Repeatable Neuropsychological Battery were also assessed throughout the 1-year study follow-up. RESULTS: Increasing CHI3L1 levels correlated with higher EDSS scores at baseline (ρ = 0.490, 95% CI 0.118-0.742, p = 0.013) and month 12 (ρ = 0.455, 95% CI 0.063-0.725, p = 0.026) and tended to be associated with a higher risk of disability progression according to EDSS scores (OR = 1.008, 95% CI 0.999-1.017, p = 0.089). Increasing CHI3L2 levels also tended to correlate with lower baseline EDSS scores (ρ = -0.366, 95% CI -0.676-0.054, p = 0.086). There was no correlation with regard to NfL levels. CONCLUSIONS: This analysis supports the association between CSF CHI3L1 levels and neurologic disability according to EDSS scores in patients with PPMS. Other chitinase-like proteins such as CHI3L2 may also be involved. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that CSF CHI3L1 is associated with neurologic disability in patients with PPMS.

Monitoring cytosolic H2O2 fluctuations arising from altered plasma membrane gradients or from mitochondrial activity.

Genetically encoded probes monitoring H2O2 fluctuations in living organisms are key to decipher redox signaling events. Here we use a new probe, roGFP2-Tpx1.C169S, to monitor pre-toxic fluctuations of peroxides in fission yeast, where the concentrations linked to signaling or to toxicity have been established. This probe is able to detect nanomolar fluctuations of intracellular H2O2 caused by extracellular peroxides; expression of human aquaporin 8 channels H2O2 entry into fission yeast decreasing membrane gradients. The probe also detects H2O2 bursts from mitochondria after addition of electron transport chain inhibitors, the extent of probe oxidation being proportional to the mitochondrial activity. The oxidation of this probe is an indicator of steady-state levels of H2O2 in different genetic backgrounds. Metabolic reprogramming during growth in low-glucose media causes probe reduction due to the activation of antioxidant cascades. We demonstrate how peroxiredoxin-based probes can be used to monitor physiological H2O2 fluctuations.