Cerebrospinal Fluid Concentrations Research Articles

Associations between normal cognitive aging and neurodegeneration

AbstractBackgroundMultiple cognitive domains, including learning, memory and psychomotor speed, show significant reductions with age. These changes are thought to reflect normal cognitive aging. However, since cerebrospinal fluid (CSF) neurodegenerative biomarkers, such as total‐tau (t‐tau) and Neurofilament light chain (NfL), also show age‐related increases in normal aging, we aimed to investigate whether age‐associated cognitive decline may be mediated by age‐associated neurodegenerative changes.MethodWe included 114 cognitively healthy participants aged 40‐80 years from The Norwegian Dementia Disease Initiation Study. All had normal concentrations of CSF Aβ42/40 ratio. Cognitively healthy was defined as demographically adjusted T‐scores ≥35 on standardized cognitive tests. We fitted mediation models using structural equation modelling (SEM), with either CSF NfL or t‐tau as a mediator between age and CERAD learning, CERAD recall, TMT‐A and TMT‐B. All variables were standardized prior to analyses; in addition, both t‐tau and NfL were log transformed due to skewness.ResultsSee table 1 for demographic and clinical characteristics. Whilst neither NfL nor t‐tau showed statistically significant mediation of age‐related cognitive decline, our results nevertheless suggest a partial mediation of NfL on age‐related cognitive decline. Here, relationships between age and CERAD learning, CERAD Recall, and TMT‐A performance were weakened whereas higher NfL was associated with worse performance, in particular for delayed memory recall. This was not observed for t‐tau in any models. See figure 1‐2.ConclusionAge‐related decline in verbal learning, memory and psychomotor speed may be partially attributable to NfL‐associated neurodegenerative changes in cognitively healthy adults. As NfL reflects axonal degeneration, these results may reflect white matter neurodegeneration in aging.

ARIA‐E, ARIA‐H, and CAA‐related inflammation: time of reconsiderations?

AbstractBackgroundEvidence from published clinical trials suggests that high‐dose of monoclonal antibodies (mAbs) are needed to significantly remove parenchymal‐deposited Aβ plaques. However, high‐dosing mAbs resulted in a 25‐35% increased risk of amyloid‐related imaging abnormalities‐edema (ARIA‐E) and ARIA‐hemorrhage (ARIA‐H) side events. Although most ARIA‐E are incidentally recognized as clinically silent during pre‐planned safety monitoring MRI scans and suggested to be managed by dose reduction or suspension, it is noticeable that half of ARIA‐E progressed to symptomatic at continued dosing and to associate with late occurrence of ARIA‐H. Of particular importance, a few of them aggravated to potentially severe brain injury or death due to fatal CAA‐related events. Increased evidence from natural history studies suggests that ARIA‐E is the iatrogenic manifestation of cerebral amyloid angiopathy‐related inflammation (CAA‐ri), a rare autoimmune encephalopathy due to raised anti‐Aß autoAbs levels in the cerebrospinal fluid (CSF).MethodNatural history study of CAA‐ri demonstrated that immunotherapy‐related ARIA‐E share several commonalities with the spontaneous occurrence of autoAbs‐related ARIA‐E, including fluid, MRI, and PET biomarker changes and the potential response to treatment outcomes.ResultThe prospective longitudinal monitoring of patients with CAA‐ri provide evidence for a regional and temporal association of ARIA‐E on MRI with focal peaks of neuroinflammation on microglial‐PET imaging. This association was strong in patients with positive CSF markers of AD (ATN positive) and comorbid CAA pathology on MRI, while it was negligible in patients with CAA disease w/o AD (ATN negative). Raised CSF concentrations of anti‐Aß autoAbs were found in all patients at (sub)acute presentation, and reduced within 5 months from the ARIA‐E index event, in parallel with evidence of radiographic resolution of ARIA‐E. At follow‐up MRI scan, the occurrence of new hemorrhagic markers (aka ARIA‐H in trials) were found only in patients with coexisting CAA and AD comorbid pathology. The MRI scales for ARIA commonly used in clinical trials only partially paralleled the clinical, biological, and MRI findings.ConclusionThis suggests that to mitigate and monitor the risk of ARIA, more sensitive, specific, cost‐effective and easy to interpret diagnostic tools and biomarkers than MRI alone will be needed for precision drug‐dose tailoring.

Associations of physical activity with cerebrospinal fluid biomarkers of neurodegeneration, neuroinflammation, and Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD) and related dementias are public health concerns often with long preclinical phases. Thus, intervention and prevention methods in midlife could prove efficacious. Cerebrospinal fluid (CSF) biomarkers can change early in the disease process and have been utilized for dementia diagnostics. Multiple health‐related lifestyle factors have been associated with risk for AD, yet existing research on lifestyle factors has focused on clinical outcomes such as cognitive decline, mild cognitive impairment and/or AD dementia; their associations with early changes in CSF are less understood. Our aim was to determine whether physical activity (PA), a modifiable lifestyle factor, is associated with biomarkers for neurodegeneration, glial activation, and inflammation.MethodParticipants were N = 204 cognitively unimpaired adults (aged 45–80 years) from the Wisconsin Registry for Alzheimer’s Prevention and the Wisconsin Alzheimer’s Disease Research Center, two on‐going, longitudinal studies of preclinical AD. PA was defined as the weekly metabolic equivalent (MET), calculated by scoring amount and intensity of mild, moderate, and vigorous exercises per week (range 0–79 METS). We assessed CSF biomarkers using robust exploratory prototype assays from the NeuroToolKit research platform (Roche Diagnostics International, Switzerland). Participants also completed demographic and health questionnaires (Table 1). We used linear regression models to assess associations between PA and CSF biomarkers, adjusting for age at biomarker assessment, sex, education, and chronic health conditions (diabetes, hypertension, cardiovascular disease).ResultPreliminary results showed that participants who engage in more PA had higher CSF S100B concentrations, a pro‐inflammatory calcium‐binding protein (standardized b change per MET = 0.0013, 95% confidence interval: 0.0003–0.0023; p = .01). No other PA‐biomarker associations were significant.ConclusionHigher PA was significantly associated with higher CSF concentration of S100B, a marker of (astro‐)glial activation. Future studies will need to examine whether PA is associated with higher S100B in individuals along the disease continuum of AD, and whether this is reflected in the blood. Longer follow‐ups may be needed to determine associations of PA with other biomarkers, where we had limited variation in this primarily healthy study cohort.

Differential performance of cerebrospinal fluid biomarker ratios and formulas to discriminate dementia with Lewy bodies from Alzheimer’s dementia and cognitively healthy people reflects high level of amyloidosis across dementia syndromes

AbstractBackgroundNeurodegeneration is a common hallmark of all dementia syndromes, whereas cerebrospinal fluid amyloid‐β may reflect amyloidosis both in Alzheimer’s dementia (AD) and in dementia with Lewy bodies (DLB). It is unknown if any biomarker profiles may help discriminate DLB from AD.MethodsConsecutive outpatients with probable DLB (fourth consensus report of the DLB Consortium) were paired with outpatients with late‐onset AD (National Institute on Aging – Alzheimer’s Association) by sex, Clinical Dementia Rating and Mini‐Mental State Examination scores, and with cognitively healthy controls by sex and age (±1 year). Genotyping of rs7412 & rs429358 (APOE) was undertaken with TaqMan® Real‐Time PCR technology. Cerebrospinal fluid concentrations of amyloid‐β (Aβ42, Aβ40, Aβ38), α‐synuclein, t‐tau and p‐tau Thr181, were assessed by enzyme‐linked immunosorbent assays. The following ratios and restructured traditional regression formulas were compared among participants: Aβ42/Aβ40, Aβ42/Aβ38, t‐tau/p‐tau, t‐tau/Aβ42, p‐tau/Aβ42, α‐synuclein/Aβ42, t‐tau/α‐synuclein, (240+1.18Xt‐tau)/Aβ42, (3.694+0.0105Xt‐tau)Xp‐tau/Aβ42, (373+0.82Xt‐tau)/Aβ42, (152+8.25Xp‐tau)/Aβ42. In addition, all formulas were considered to correspond to an AD profile if >1, while t‐tau/Aβ42>0.5 and p‐tau/Aβ42>0.08 were also measured, significance at p<0.05.ResultsOverall, 27 participants with DLB (78.48±9.0 years‐old, CDR sum‐of‐boxes 10.96±3.8, eleven APOE‐ε4 carriers) were paired with 27 participants with AD (81.00±5.8 years‐old, CDR sum‐of‐boxes 10.44±3.9, twelve APOE‐ε4 carriers) and 27 controls (78.48±8.7 years‐old, CDR sum‐of‐boxes 0.30±0.8, four APOE‐ε4 carriers); two thirds were women. Only for APOE‐ε4 carriers, t‐tau/Aβ42 (p = 0.065) and t‐tau/α‐synuclein (p = 0.073) were marginally significantly higher in AD. Only for APOE‐ε4 non‐carriers, Aβ42/Aβ38 was higher (p = 0.009) and α‐synuclein/Aβ42 was lower (p = 0.043) in DLB. The t‐tau/Aβ42>0.5 (p = 0.039) and p‐tau/Aβ42>0.08 (p = 0.042) ratios were able to discriminate patients with AD from controls, but not from patients with DLB, regardless of APOE‐ε4 carrier status. All formulas were able to discriminate patients with AD from controls (p<0.02), but only (152+8.25Xp‐tau)/Aβ42>1 was able to discriminate patients with AD from patients with DLB (p = 0.025), regardless of APOE‐ε4 carrier status.ConclusionsAmyloidosis and neurodegeneration are modulated by APOE‐ε4 carrier status and may differentially affect the discriminative power of cerebrospinal fluid biomarker ratios for diagnosis of dementia syndromes. The best formula to discriminate patients with AD from patients with DLB and controls was (152+8.25Xp‐tau)/Aβ42>1. (Supported by FAPESP grant #2015/10109‐5)

Efficacy and Safety of Orelabrutinib-Containing Regime (TORM) As First-Line Therapy in Primary Central Nervous System Lymphoma (PCNSL): A Retrospective Analysis

Introduction: Primary central nervous system lymphoma (PCNSL) is a rare, aggressive extranodal lymphoma with poor prognosis. Currently there is no standard therapeutic strategy for PCNSL, and high-dose methotrexate-based regimens remain the first option (Siegal et al. Acta Haematologica 2019). Recently, studies have shown that Bruton's tyrosine kinase (BTK) plays a crucial part in B cell receptor and Toll-like receptor signaling pathways, which are constitutively active in PCNSL (Shen et al. Front Oncol. 2022). BTK inhibitor has been proven effective in treating chronic lymphocytic leukemia and other B-cell lymphomas (Yoshitaka et al. Neuro-Oncology 2021). Orelabrutinib is a novel and highly selective BTK inhibitor with high cerebrospinal fluid (CSF) concentration, which has demonstrated efficacy and safety in PCNSL (Wu et al. Invest New Drugs. 2022). Thus, we conducted a retrospective study to evaluate the efficacy and safety of the orelabrutinib-containing regimens as first-line therapy for patients (pts) with PCNSL. Methods: This isa retrospective analysis of pts with PCNSL who received TORM regimens (temozolomide 150 mg/m 2 day 2-5; orelabrutinib 150 mg qd day 2-21; rituximab 375 mg/m 2 day 1; methotrexate 3.5 g/m 2 day 2; 3 weeks per cycle) as first-line induction therapy between June 2021 and April 2023. It was proposed to receive autologous stem cells transplantation (ASCT) as consolidation therapy or orelabrutinib monotherapy as maintenance after TORM therapy when deemed necessary. The primary endpoint was overall response rate (ORR) according to the International PCNSL Collaborative Group (IPCG) criteria. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. Results: Twelve pts (8 males) with PCNSL were included, with a median age of 63.5 years (range, 40-77). All pts had a histologically confirmed diffuse large B-cell lymphoma and a history of deep intracranial lesions. 8 pts (66.7%) had non-germinal center B-cell-like subtypes. 5 pts (41.7%) had an Eastern Cooperative Oncology Group performance status of ≥2, and 10 pts (83.3%) had International Extranodal Lymphoma Study Group scores ≥2. 4 pts (33.3%) underwent ASCT after induction therapy and 4 pts (33.3%) received orelabrutinib maintenance monotherapy. As of the cut-off date (July 1, 2023), the median follow-up was 11.7 (range, 1.9-23.0) months, and median treatment cycle was 6 cycles (range, 2-9). All 12 pts were evaluated for the treatment response. An interim evaluation after 3/4 cycles was available for 12 pts, showing complete remission (CR) rate of 83.3% (10/12), partial response (PR) rate of 16.7% (2/12), giving an ORR of 100.0% (12/12, Table 1). At data cutoff, of all 12 evaluable pts, the best ORR was 100.0% (12/12), with all pts achieved CR ( Table 1). The median time to response was 1.7 (range, 0.7-2.4) months. Of 12 responders, 9 had an ongoing response, 2 developed progressive disease, and 1 died of covid-19 infection ( Figure 1). Median PFS was 22.6 months, with a 95% CI of 10.4-not reached (NR). Based one OS event, median OS was 22.6 months (95% CI, NR-NR). The most common AEs were anemia. Reported AEs were generally manageable and resolved soon after supportive treatment. AEs associated with off-target activities such as atrial fibrillation, diarrhea, and major hemorrhage were not reported. Conclusions: TORM regimens demonstrated encouraging efficacy and well-tolerated safety profile among pts with PCNSL in this retrospective study. This orelabrutinib-containing regimens may provide a potential treatment strategy for pts with PCNSL.

Methotrexate in Combination with Orelabrutinib, Thiotepa, and Rituximab (R-MTO) Followed By Autologous Stem-Cell Transplant for Primary Central Nervous System Lymphoma Treatment

Background: Primary central nervous system lymphoma (PCNSL) is a rare, aggressive B-cell malignancy. Despite the possibility of a cure, the prognosis remains poor. The standard treatment includes high-dose methotrexate and rituximab, followed by consolidation with either whole-brain radiation therapy or autologous stem cell transplantation (ASCT). However, there is still no clear consensus on the best treatment approach. To improve outcomes, we incorporated thiotepa chemotherapy, which has shown promising activity in inhibiting tumor growth by disrupting DNA bonds, into the regimen. Additionally, we introduced orelabrutinib, a novel and potent BTK inhibitor with high cerebrospinal fluid concentrations, which has demonstrated efficacy in treating PCNSL. In light of these findings, we conducted a clinical study to evaluate the efficacy and safety of a combination regimen of thiotepa, orelabrutinib, and methotrexate with rituximab (R-MTO) followed by autologous hematopoietic stem cell transplantation (HSCT) in patients with PCNSL. Methods: This is an ongoing, single-center, single-arm, open-label study conducted between April 2022 and July 2023. The study enrolled patients aged 18-80 years diagnosed with PCNSL. The patients received 5-8 cycles of R-MTO regimen as induction therapy, consisting of rituximab 375 mg/m 2 iv on day 0, MTX 3.5 g/m 2 iv on day1, thiotepa, 30-40 mg/m 2 on day 4 and orelabrutinib 150 mg qd po for 3 weeks per cycle). After completing the R-MTO therapy, patients were proposed to receive orelabrutinib monotherapy as maintenance treatment for up to 2 years. The efficacy was assessed by MRI/PET per the International PCNSL Collaborative Group (IPCG) criteria. Patients who did not experience disease progression subsequently underwent consolidation treatment with high-dose chemotherapy (HCT) plus ASCT. The HCT regimen involved busulfan 3.2 mg/kg on days -5, -4, thiotepa 250 mg/m 2 on days -7 and -6, cytarabine 2g/m 2 q12h on days -3 and -2, followed by reinfusion of stem cells on day 0. The primary endpoint of the study was progression-free survival (PFS) at 2 years, evaluated by intention-to-treat (ITT). Secondary endpoints included complete response (CR) rate, overall response rate (ORR), overall survival (OS) and toxicities. Results: Between April 2022 and July 2023, a total of 19 patients with PCNSL were enrolled in our study, including 16 who were newly diagnosed and had not received any prior treatment. The median age of the patients was 62 years, ranging from 31 to 72, with 9 out of 19 (47.37%) being male. By the data cutoff, all the patients had completed 4 cycles of treatment. Additionally, 8 out of 19 (42.11%) patients had completed six cycles of treatment, and 2 out of 19 (10.52%) patients had completed 7 to 8 cycles of treatment. The ORR was 94.73% (18/19), and the CR rate was 89.47% (17/19) after 4 cycles of treatment. However, one patient with a P53 mutation progressed after 2 cycles of treatment and unfortunately died 3.8 months after diagnosis. Among the six patients who underwent autologous HSCT, all of them (100%) remained in CR. One patient died due to a COVID-19 infection after 6 cycles of R-MTO and ASCT. The most common hematological adverse events associated with the R-MTO regimen were mild to moderate (grade 1-2) decreases in neutrophil count, which typically resolved within a few days. Conclusions: The R-MTO induction treatment has demonstrated notable efficacy in achieving higher response rates among patients with PCNSL, and the associated adverse events are manageable.

Prediction of trough concentration and ALK occupancy in plasma and cerebrospinal fluid using physiologically based pharmacokinetic modeling of crizotinib, alectinib, and lorlatinib

Prediction of trough concentration and ALK occupancy in plasma and cerebrospinal fluid using physiologically based pharmacokinetic modeling of crizotinib, alectinib, and lorlatinib

Specific serum autoantibodies predict the development and progression of Alzheimer’s disease with high accuracy

Autoimmunity plays a key role in the pathogenesis of Alzheimer’s disease (AD). However, whether autoantibodies in peripheral blood can be used as biomarkers for AD has been elusive. Serum samples were obtained from 1,686 participants, including 767 with AD, 146 with mild cognitive impairment (MCI), 255 with other neurodegenerative diseases, and 518 healthy controls. Specific autoantibodies were measured using a custom-made immunoassay. Multivariate support vector machine models were employed to investigate the correlation between serum autoantibody levels and disease states. As a result, seven candidate AD-specific autoantibodies were identified, including MAPT, DNAJC8, KDM4D, SERF1A, CDKN1A, AGER, and ASXL1. A classification model with high accuracy (area under the curve (AUC) = 0.94) was established. Importantly, these autoantibodies could distinguish AD from other neurodegenerative diseases and out-performed amyloid and tau protein concentrations in cerebrospinal fluid in predicting cognitive decline (P < 0.001). This study indicated that AD onset and progression are possibly accompanied by an unappreciated serum autoantibody response. Therefore, future studies could optimize its application as a convenient biomarker for the early detection of AD.

Diagnostic Performance of Cerebrospinal Fluid Neurofilament Light Chain and Soluble Amyloid-β Protein Precursor β in the Subcortical Small Vessel Type of Dementia.

The subcortical small vessel type of dementia (SSVD) is a common subtype of vascular dementia, but there is a lack of disease-specific cerebrospinal fluid (CSF) biomarkers. We investigated whether CSF concentrations of neurofilament light chain (NFL), soluble amyloid-β protein precursor α (sAβPPα), sAβPPβ, and CSF/serum albumin ratio could separate SSVD from healthy controls, Alzheimer's disease (AD), and mixed dementia (combined AD and SSVD). This was a mono-center study of patients with SSVD (n = 38), AD (n = 121), mixed dementia (n = 62), and controls (n = 96). The CSF biomarkers were measured using immunoassays, and their independent contribution to the separation between groups were evaluated using the Wald test. Then, the area under the receiver operating characteristics curve (AUROC) and 95% confidence intervals (CIs) were calculated. Elevated neurofilament light chain (NFL) and decreased sAβPPβ independently separated SSVD from controls, and sAβPPβ also distinguished SSVD from AD and mixed dementia. The combination of NFL and sAβPPβ discriminated SSVD from controls with high accuracy (AUROC 0.903, 95% CI: 0.834-0.972). Additionally, sAβPPβ combined with the core AD biomarkers (amyloid-β42, total tau, and phosphorylated tau181) had a high ability to separate SSVD from AD (AUROC 0.886, 95% CI: 0.830-0.942) and mixed dementia (AUROC 0.903, 95% CI: 0.838-0.968). The high accuracy of NFL and sAβPPβ to separate SSVD from controls supports that SSVD is a specific diagnostic entity. Moreover, SSVD was distinguished from AD and mixed dementia using sAβPPβ in combination with the core AD biomarkers.

EXTH-56. CSF PENETRATION COMPARISON OF TWO ORAL FORMULATIONS OF APL-101 IN A PRE-CLINICAL NON-HUMAN PRIMATE MODEL

Abstract Vebreltinib (APL-101) is a potent c-Met inhibitor which has shown efficacy in murine pre-clinical models and is under clinical trial evaluation for several cancer types, including adult high-grade glioma. The capsule formulation (APL-101-Cap) was reformulated as a pill (APL-101-Pill) with the expectation of increasing bioavailability. We determined and compared the plasma pharmacokinetics (PK) and cerebrospinal fluid (CSF) penetration of APL-101-Cap and APL-101-Pill in a non-human primate (NHP) model. METHODS: Seven animals, previously developed as serial CSF access models, were utilized across all studies. One NHP was studied with both formulations. Both formulations were administered orally as a single drug/single dose in serial studies, followed by serial plasma and CSF sample collections from 0-96 hours. Dosages: APL-101-Cap 3.25 mg/kg (n = 3) or 6.5 mg/kg (n = 4) and APL-101-Pill 5 mg/kg (n = 4). The resulting plasma concentrations from each formulation were quantified by LC-MS/MS. PK parameters were calculated via noncompartmental methods, and results were analyzed to assess CNS penetration (AUCCSF:AUCPlasma) and compare formulations. RESULTS: Mean (range) for plasma and CSF PK exposure [AUCLAST (hr*ng/mL)] reported. APL-101-Cap plasma exposure, regardless of dose, was more variable than APL-101-Pill. APL-101-Pill had lower exposure in both plasma (AUC 1893.0 (841-2865)] and CSF [AUC 27.7 (5.0-65.0)] than APL-101-Cap regardless of dose [(3.25 mg/kg): plasma AUC 9621.0 (1331-23132) and CSF AUC 688.0 (24-1352); 6.5 mg/kg: plasma AUC 6208.0 (1424-19800) and CSF AUC 606.0 (34-1179)]. CNS penetrance was higher with APL-101-Cap (3.2% [0.5-5.8%] at 3.25mg/kg; 4.2% (2.4-6%) at 6.5 mg/kg), but also more variable when compared to APL-101-Pill (1.2% [0.6-2.3%]). For APL-101-Cap, one animal at 3.25 mg/kg and two animals at 6.25 mg/kg had undetectable CSF concentrations. CONCLUSION: In this NHP model, single-dose oral administration of APL-101-Pill resulted in lower, but less variable plasma and CSF exposure compared to APL-101-Cap. APL-101-Cap CSF exposure was unaffected by dose escalation.

Brain-Derived Neurotrophic Factor (BDNF) Concentration Levels in Cerebrospinal Fluid and Plasma in Patients With Glioblastoma: A Prospective, Observational, Controlled Study.

Objective Glioblastomas (GBMs) are among the most frequent and most malignant of untreatable brain tumors. A GBM marker could accelerate diagnosis and facilitate therapeutic monitoring. This prospective, observational, controlled study compared brain-derived neurotrophic factor (BDNF) levels in cerebrospinal fluid (CSF) and plasma between patients with GBM and a control group. Materials and methods Patients in the observational group underwent elective GBM resection (n=24, 55.8%).Control patients (n=19, 44.2%) had elective brain surgery for an unrelated, non-neoplastic, non-traumatic pathology. We measured BDNF levels in tumors, CSF, and plasma with enzyme-linked immunosorbent assay (ELISA). Peripheral blood and CSF samples were collected before surgery, and tumors were sampled intraoperatively. We analyzed correlations between BDNF levels and patient sex, age, seizures, smoking, diabetes mellitus (DM), and the use of selected antiepileptic drug (AED) and antihypertensive drug groups. Results The mean CSF BDNF concentration was significantly lower in patients with GBM (6.5 pg/mL) than in controls (11.48 pg/mL) (p=0.002). Similarly, the mean plasma BDNF concentration was significantly lower in patients with GBM (288.59 pg/mL) than in controls (574.06 pg/mL) (p=0.0005). None of the examined factors influenced CSF, plasma, or tumor tissue BDNF concentrations (p>0.05). Conclusion Plasma and CSF BDNF levels were significantly lowerin adults with GBM than in controls. Thus, CSF and plasma BDNF levels may aid in GBM diagnoses. Further prospective studies are required.

Validation of a quantitative liquid chromatography tandem mass spectrometry assay for linezolid in cerebrospinal fluid and its application to patients with HIV-associated TB-meningitis

Tuberculous meningitis treatment outcomes are poor and alternative regimens are under investigation. Reliable methods to measure drug concentrations in cerebrospinal fluid are required to evaluate distribution into the cerebrospinal fluid. A simple and quick method was developed and validated to analyse linezolid in human cerebrospinal fluid. Samples were prepared by protein precipitation followed by isocratic liquid chromatography and tandem mass spectrometry. The run time was 3.5 min. Accuracy and precision were assessed in three independent validation batches with a calibration range of 0.100–20.0 μg/mL. The method was used to analyse cerebrospinal fluid samples from patients with tuberculous meningitis enrolled in a clinical trial. Potentially infective patient samples could be decontaminated using Nanosep® nylon and Costar® nylon filter tubes under biosafety level 3 conditions before analysis. The filtration process did not significantly affect the quantification of linezolid. Linezolid concentration in cerebrospinal fluid obtained from tuberculous meningitis patients ranged from 0.197 μg/mL to 15.0 μg/mL. The ratio between average CSF and plasma linezolid concentrations varied with time, reaching a maximum of 0.9 at 6 h after dosing.

Mechanisms behind changes of neurodegeneration biomarkers in plasma induced by sleep deprivation.

Acute sleep deprivation has been shown to affect cerebrospinal fluid and plasma concentrations of biomarkers associated with neurodegeneration, though the mechanistic underpinnings remain unknown. This study compared individuals who, for one night, were either subject to total sleep deprivation or free sleep, (i) examining plasma concentrations of neurodegeneration biomarkers the morning after sleep deprivation or free sleep and (ii) determining how overnight changes in biomarkers plasma concentrations correlate with indices of meningeal lymphatic and glymphatic clearance functions. Plasma concentrations of amyloid-β 40 and 42, phosphorylated tau peptide 181, glial fibrillary acid protein and neurofilament light were measured longitudinally in subjects who from Day 1 to Day 2 either underwent total sleep deprivation (n = 7) or were allowed free sleep (n = 21). The magnetic resonance imaging contrast agent gadobutrol was injected intrathecally, serving as a cerebrospinal fluid tracer. Population pharmacokinetic model parameters of gadobutrol cerebrospinal fluid-to-blood clearance were utilized as a proxy of meningeal lymphatic clearance capacity and intrathecal contrast-enhanced magnetic resonance imaging as a proxy of glymphatic function. After one night of acute sleep deprivation, the plasma concentrations of amyloid-β 40 and 42 were reduced, but not the ratio, and concentrations of the other biomarkers were unchanged. The overnight change in amyloid-β 40 and 42 plasma concentrations in the sleep group correlated significantly with indices of meningeal lymphatic clearance capacity, while this was not seen for the other neurodegeneration biomarkers. However, overnight change in plasma concentrations of amyloid-β 40 and 42 did not correlate with the glymphatic marker. On the other hand, the overnight change in plasma concentration of phosphorylated tau peptide 181 correlated significantly with the marker of glymphatic function in the sleep deprivation group but not in the sleep group. The present data add to the evidence of the role of sleep and sleep deprivation on plasma neurodegeneration concentrations; however, the various neurodegeneration biomarkers respond differently with different mechanisms behind sleep-induced alterations in amyloid-β and tau plasma concentrations. Clearance capacity of meningeal lymphatics seems more important for sleep-induced changes in amyloid-β 40 and 42 plasma concentrations, while glymphatic function seems most important for change in plasma concentration of phosphorylated tau peptide 181 during sleep deprivation. Altogether, the present data highlight diverse mechanisms behind sleep-induced effects on concentrations of plasma neurodegeneration biomarkers.

Quantification of Bile Acids in Cerebrospinal Fluid: Results of an Observational Trial.

(1) Background: Bile acids, known as aids in intestinal fat digestion and as messenger molecules in serum, can be detected in cerebrospinal fluid (CSF), although the blood-brain barrier is generally an insurmountable obstacle for bile acids. The exact mechanisms of the occurrence, as well as possible functions of bile acids in the central nervous system, are not precisely understood. (2) Methods: We conducted a single-center observational trial. The concentrations of 15 individual bile acids were determined using an in-house LC-MS/MS method in 54 patients with various acute and severe disorders of the central nervous system. We analyzed CSF from ventricular drainage taken within 24 h after placement, and blood samples were drawn at the same time for the presence and quantifiability of 15 individual bile acids. (3) Results: At a median time of 19.75 h after a cerebral insult, the concentration of bile acids in the CSF was minute and almost negligible. The CSF concentrations of total bile acids (TBAs) were significantly lower compared to the serum concentrations (serum 0.37 µmol/L [0.24, 0.89] vs. 0.14 µmol/L [0.05, 0.43]; p = 0.033). The ratio of serum-to-CSF bile acid levels calculated from the respective total concentrations were 3.10 [0.94, 14.64] for total bile acids, 3.05 for taurocholic acid, 14.30 [1.11, 27.13] for glycocholic acid, 0.0 for chenodeoxycholic acid, 2.19 for taurochenodeoxycholic acid, 1.91 [0.68, 8.64] for glycochenodeoxycholic acid and 0.77 [0.0, 13.79] for deoxycholic acid; other bile acids were not detected in the CSF. The ratio of CSF-to-serum S100 concentration was 0.01 [0.0, 0.02]. Serum total and conjugated (but not unconjugated) bilirubin levels and serum TBA levels were significantly correlated (total bilirubin p = 0.031 [0.023, 0.579]; conjugated bilirubin p = 0.001 [0.193, 0.683]; unconjugated p = 0.387 [-0.181, 0.426]). No correlations were found between bile acid concentrations and age, delirium, intraventricular blood volume, or outcome measured on a modified Rankin scale. (4) Conclusions: The determination of individual bile acids is feasible using the current LC-MS/MS method. The results suggest an intact blood-brain barrier in the patients studied. However, bile acids were detected in the CSF, which could have been achieved by active transport across the blood-brain barrier.

Exploratory Tau Biomarker Results From a Multiple Ascending-Dose Study of BIIB080 in Alzheimer Disease

Accumulation of hyperphosphorylated, tangled microtubule-associated protein tau (MAPT) is a pathological hallmark of Alzheimer disease (AD) associated with disease progression and cognitive decline. To evaluate the effect of tau synthesis reduction on tau biomarkers in patients with mild AD. This randomized clinical trial was a double-blind, placebo-controlled 36-week multiple-ascending dose (MAD) phase 1b trial (October 2017 to September 2020), followed by a 64- or 71-week open-label long-term extension (LTE) (October 2019 to May 2022). After being assessed for eligibility at 12 sites in Canada and Europe, participants with mild AD and confirmed amyloid pathology were randomized 3:1 (BIIB080:placebo) in 4 dose cohorts. Intrathecal administration of BIIB080, a MAPT-targeting antisense oligonucleotide, or placebo. Active dose arms included 10 mg every 4 weeks, 30 mg every 4 weeks, 60 mg every 4 weeks, and 115 mg every 12 weeks during the MAD period and 60 mg every 12 weeks or 115 mg every 12 weeks during the LTE. The original primary end point was safety. Additionally, BIIB080, total tau (t-tau), and phosphorylated tau 181 (p-tau181) cerebrospinal fluid (CSF) concentrations were evaluated. Tau positron emission tomography (PET) was collected in a substudy, and standard uptake value ratios (SUVRs) were calculated in a priori-defined composite regions of interest. Of 102 participants assessed for eligibility, 46 participants with mild AD were enrolled; 23 (50%) were female, and mean (SD) age was 65.8 (5.70) years. BIIB080 was generally well tolerated and was associated with a dose-dependent reduction in CSF t-tau and p-tau181 in the MAD period (56% reduction; 95% CI, 50% to 62%; and 51% reduction; 95% CI, 38% to 63%, of CSF t-tau in the 2 higher-dose cohorts) that continued and/or was maintained through quarterly dosing in the LTE. Tau PET demonstrated reduced accumulation vs placebo at week 25 (n = 13). At week 100, tau PET showed a reduction from baseline across all regions assessed (n = 12), with the largest reductions from baseline observed in the temporal composite (-0.71 SUVR; 95% CI, -1.40 to -0.02). A moderate correlation was observed between model-predicted cumulative CSF drug exposure and tau PET change. In this randomized clinical trial, BIIB080 reduced tau biomarkers, including CSF t-tau, CSF p-tau181, and tau PET, which is associated with cognitive decline, in participants with mild AD. Effects of BIIB080 on biomarkers and clinical outcomes are being further evaluated in a phase 2 trial. ClinicalTrials.gov Identifier: NCT03186989.

Evaluation of cerebrospinal fluid levels of synaptic vesicle protein, VAMP-2, across the sporadic Alzheimer’s disease continuum

BackgroundSynapse loss is an early event that precedes neuronal death and symptom onset and is considered the best neuropathological correlate of cognitive decline in Alzheimer’s disease (AD). Vesicle-associated membrane protein 2 (VAMP-2) has emerged as a promising biomarker of AD-related synapse degeneration in cerebrospinal fluid (CSF). The aim of this study was to explore the CSF profile of VAMP-2 across the AD continuum in relation to core AD biomarkers, other synaptic proteins, neurogranin (Ng) and synaptosomal-associated Protein-25 kDa (SNAP-25) and cognitive performance.MethodsWe developed a digital immunoassay on the Single Molecule Array platform to quantify VAMP-2 in CSF and used existing immunoassays to quantify Ng, SNAP-25 and core CSF AD biomarkers. The clinical study included 62 cognitively unimpaired AD biomarker-negative subjects and 152 participants across the AD continuum from the SPIN cohort (Sant Pau Initiative on Neurodegeneration). Cognitive measures of episodic, semantic, executive and visuospatial domains and global cognition were included. Statistical methods included χ2 tests, spearman correlation, and ANCOVA analyses.ResultsThe VAMP-2 assay had a good analytical performance (repeatability 8.9%, intermediate precision 10.3%). Assay antibodies detected native VAMP-2 protein in human brain homogenates. CSF concentrations of VAMP-2, neurogranin and SNAP-25 were lower in preclinical AD stage 1 compared to controls and higher at later AD stages compared to AD stage 1 and were associated with core AD biomarkers, particularly total tau (adj. r2 = 0.62 to 0.78, p < 0.001). All three synaptic proteins were associated with all cognitive domains in individuals on the AD continuum (adj. r2 = 0.04 to 0.19, p < 0.05).ConclusionsOur novel digital immunoassay accurately measures VAMP-2 changes in CSF, which reflect AD biomarkers and cognitive performance across multiple domains.

CSF, Blood, and MRI Biomarkers in Skogholt's Disease-A Rare Neurodegenerative Disease in a Norwegian Kindred.

Skogholt's disease is a rare neurological disorder that is only observed in a small Norwegian kindred. It typically manifests in adulthood with uncharacteristic neurological symptoms from both the peripheral and central nervous systems. The etiology of the observed cerebral white matter lesions and peripheral myelin pathology is unclear. Increased cerebrospinal fluid (CSF) concentrations of protein have been confirmed, and recently, very high concentrations of CSF total and phosphorylated tau have been detected in Skogholt patients. The symptoms and observed biomarker changes in Skogholt's disease are largely nonspecific, and further studies are necessary to elucidate the disease mechanisms. Here, we report the results of neurochemical analyses of plasma and CSF, as well as results from the morphometric segmentation of cerebral magnetic resonance imaging. We analyzed the biomarkers Aβ1--42, Aβ1-40, Aβx-38, Aβx-40, Aβx-42, total and phosphorylated tau, glial fibrillary acidic protein, neurofilament light chain, platelet-derived growth factor receptor beta, and beta-trace protein. All analyzed CSF biomarkers, except neurofilament light chain and Aβ1/x-42, were increased several-fold. In blood, none of these biomarkers were significantly different between the Skogholt and control groups. MRI volumetric segmentation revealed decreases in the ventricular, white matter, and choroid plexus volumes in the Skogholt group, with an accompanying increase in white matter lesions. The cortical thickness and subcortical gray matter volumes were increased in the Skogholt group. Pathophysiological changes resulting from choroidal dysfunction and/or abnormal CSF turnover, which may cause the increases in CSF protein and brain biomarker levels, are discussed.

Association between metals and metalloids with cognitive status in Mild Cognitive Impairment subjects

Abstract Mild Cognitive Impairment (MCI) is regarded as a transitional state between normal aging and dementia. Several risk factors have been related to MCI and dementia vulnerability. Among these, metals and metalloids have been hypothesized to affect dementia risk. Our objective was to study the associations between metals and metalloids (cadmium, copper, iron, manganese, selenium, zinc) concentrations in serum and cerebrospinal fluid (CSF) with cognitive impairment status of MCI subjects. 144 individuals newly diagnosed with MCI were recruited at Neurology Memory Clinics at Modena and Reggio Emilia Hospitals (Italy) in the period 2019-2022. The concentrations of elements in paired serum/CSF were determined using inductively coupled plasma mass spectrometry. Participants’ global cognitive status was assessed using the Mini-Mental State Examination (MMSE). Muti-adjusted spline regression analyses were performed to assess the relation between the serum/CSF concentrations and MMSE. Median serum and CSF concentrations were generally higher in men than women, except copper in serum and iron in CSF demonstrating higher concentrations in women. A positive linear association emerged between serum iron concentrations and MMSE, while a slight negative one emerged for serum selenium levels. Cadmium in serum was positively associated with MMSE until 0.2 µg/L and then the association became null, while in CSF a U-shaped relation emerged. A U-shaped relation was also observed for serum copper and CSF iron and manganese levels. CSF selenium concentrations were inversely related to MMSE, although above 5 µg/L the curve flattened. Zinc exhibited the same pattern of association in both serum and CSF, i.e., an inverted U-shaped one. These findings suggest that CSF and serum content of the investigated elements may be differently related with global cognitive status in MCI subjects. Higher levels of selenium and zinc, in particular, are associated with lower MMSE score. Key messages • Heavy metals and metalloids display different pattern of association with global cognitive status. • High levels of selenium and zinc are inversely related with global cognitive status in MCI subjects.

COVID-19 Recovery: Consistent Absence of Cerebrospinal Fluid Biomarker Abnormalities in Patients With Neurocognitive Post-COVID Complications.

To investigate evidence of residual viral infection, intrathecal immune activation, central nervous system (CNS) injury, and humoral responses in cerebrospinal fluid (CSF) and plasma in patients recovering from coronavirus disease 2019 (COVID-19), with or without neurocognitive post-COVID condition (PCC). Thirty-one participants (25 with neurocognitive PCC) underwent clinical examination, lumbar puncture, and venipuncture ≥3 months after COVID-19 symptom onset. Healthy volunteers were included. CSF and plasma severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid and spike antigen (N-Ag, S-Ag), and CSF biomarkers of immune activation and neuronal injury were analyzed. SARS-CoV-2 N-Ag or S-Ag were undetectable in all samples and no participant had pleocytosis. We detected no significant differences in CSF and plasma cytokine concentrations, albumin ratio, IgG index, neopterin, β2M, or in CSF biomarkers of neuronal injury and astrocytic damage. Furthermore, principal component analysis (PCA1) analysis did not indicate any significant differences between the study groups in the marker sets cytokines, neuronal markers, or anti-cytokine autoantibodies. We found no evidence of ongoing viral replication, immune activation, or CNS injury in plasma or CSF in patients with neurocognitive PCC compared with COVID-19 controls or healthy volunteers, suggesting that neurocognitive PCC is a consequence of events suffered during acute COVID-19 rather than persistent viral CNS infection or residual CNS inflammation.

Cerebrospinal Fluid Proteomic Changes after Nusinersen in Patients with Spinal Muscular Atrophy.

Disease-modifying treatments have transformed the natural history of spinal muscular atrophy (SMA), but the cellular pathways altered by SMN restoration remain undefined and biomarkers cannot yet precisely predict treatment response. We performed an exploratory cerebrospinal fluid (CSF) proteomic study in a diverse sample of SMA patients treated with nusinersen to elucidate therapeutic pathways and identify predictors of motor improvement. Proteomic analyses were performed on CSF samples collected before treatment (T0) and at 6 months (T6) using an Olink panel to quantify 1113 peptides. A supervised machine learning approach was used to identify proteins that discriminated patients who improved functionally from those who did not after 2 years of treatment. A total of 49 SMA patients were included (10 type 1, 18 type 2, and 21 type 3), ranging in age from 3 months to 65 years. Most proteins showed a decrease in CSF concentration at T6. The machine learning algorithm identified ARSB, ENTPD2, NEFL, and IFI30 as the proteins most predictive of improvement. The machine learning model was able to predict motor improvement at 2 years with 79.6% accuracy. The results highlight the potential application of CSF biomarkers to predict motor improvement following SMA treatment. Validation in larger datasets is needed.