Cerebrospinal fluid biomarkers in clinically isolated syndromes and multiple sclerosis

Cystatin C Plays a Sex-Dependent Detrimental Role in Experimental Autoimmune Encephalomyelitis

The cysteine protease inhibitor Cystatin C (CST3) is highly expressed in the brains of multiple sclerosis (MS) patients and C57BL/6J mice with experimental autoimmune encephalomyelitis (EAE; a model of MS), but its roles in the diseases are unknown. Here, we show that CST3 plays a detrimental function in myelin oligodendrocyte glycoprotein 35–55 (MOG_35–55)-induced EAE but only in female animals. Female Cst3 null mice display significantly lower clinical signs of disease compared to wild-type (WT) littermates. This difference is associated with reduced interleukin-6 production and lower expression of key proteins (CD80, CD86, major histocompatibility complex [MHC] II, LC3A/B) involved in antigen processing, presentation, and co-stimulation in antigen-presenting cells (APCs). In contrast, male WT and Cst3^−/− mice and cells show no differences in EAE signs or APC function. Further, the sex-dependent effect of CST3 in EAE is sensitive to gonadal hormones. Altogether, we have shown that CST3 has a sex-dependent role in MOG_35–55-induced EAE.

Cystatin C (CST3) is increased in the brains of multiple sclerosis patients, but its role is unknown. In a mouse model of the disease, Hoghooghi et al. find that CST3 has a detrimental function but only in female animals. The effect is related to activation of antigen-presenting cells of the immune system.

A literature review of biosensors for multiple sclerosis: Towards personalized medicine and point-of-care testing

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system that leads to severe motor and sensory deficits in patients. Although some biomolecules in serum or cerebrospinal fluid have been suggested as biomarkers for MS diagnosis, following disease activity and monitoring treatment response, most of these potential biomarkers are not currently in clinical use and available for all patients. The reasons behind this are generally related to insufficient robustness of biomarker or technical difficulties, high prices, and requirements for technical personnel for their detection. Point-of-care testing (POCT) is an emerging field of healthcare that can be applied at the hospital as well as at home without the need for a centralized laboratory. Biosensor devices offer a convenient means for POCT. A biosensor is a compact analytical device that uses a bioreceptor, such as an antibody, enzyme, or oligonucleotide, to capture the analyte of interest. The interaction between the analyte and the bioreceptor is sensed and transduced into a suitable signal by the signal transducer. The advantages of using a biosensor for detecting the biomolecule of interest include speed, simplicity, accuracy, relatively lower cost, and lack of requirements for highly qualified personnel to perform the testing. Owing to these advantages and with the help of innovations in biosensor development technologies, there has been a great interest in developing biosensor devices for MS in recent years. Hence, the purpose of this review was to provide researchers with an up-to-date summary of the literature as well as to highlight the challenges and opportunities in this translational research field. In addition, because this is a highly interdisciplinary field of study, potentially concerning MS specialists, neurologists, biomedical researchers, and engineers, another aim of this review was to bridge the gap between these disciplines.

High Diagnostic Accuracy of RT-QuIC Assay in a Prospective Study of Patients with Suspected sCJD

The early and accurate in vivo diagnosis of sporadic Creutzfeldt–Jakob disease (sCJD) is essential in order to differentiate CJD from treatable rapidly progressive dementias. Diagnostic investigations supportive of clinical CJD diagnosis include magnetic resonance imaging (MRI), electroencephalogram (EEG), 14-3-3 protein detection, and/or real-time quaking-induced conversion (RT-QuIC) assay positivity in the cerebrospinal fluid (CSF) or in other tissues. The total CSF tau protein concentration has also been used in a clinical setting for improving the CJD diagnostic sensitivity and specificity. We analyzed 182 CSF samples and 42 olfactory mucosa (OM) brushings from patients suspected of having sCJD with rapidly progressive dementia (RPD), in order to determine the diagnostic accuracy of 14-3-3, the total tau protein, and the RT-QuIC assay. A probable and definite sCJD diagnosis was assessed in 102 patients. The RT-QuIC assay on the CSF samples showed a 100% specificity and a 96% sensitivity, significantly higher compared with 14-3-3 (84% sensitivity and 46% specificity) and tau (85% sensitivity and 70% specificity); however, the combination of RT-QuIC testing of the CSF and OM samples resulted in 100% sensitivity and specificity, proving a significantly higher accuracy of RT-QuIC compared with the surrogate biomarkers in the diagnostic setting of patients with RPD. Moreover, we showed that CSF blood contamination or high protein levels might interfere with RT-QuIC seeding. In conclusion, we provided further evidence that the inclusion of an RT-QuIC assay of the CSF and OM in the diagnostic criteria for sCJD has radically changed the clinical approach towards the diagnosis.

Prediction of Conversion from Clinically Isolated Syndrome to Multiple Sclerosis According to Baseline Characteristics: A Prospective Study

Objective

Clinically isolated syndrome (CIS) is a clinical state that proceeds with inflammation and demyelination, suggestive of multiple sclerosis (MS) in the central nervous system in the absence of other alternative diagnoses. The purpose of this study was to determine in a prospective cohort, the predictor factors in conversion from CIS to MS on the basis of clinical, magnetic resonance (MR) imaging and cerebrospinal fluid (CSF) findings.

Methods

Forty-one CIS patients were included in this study and followed up for at least two years.

Results

Clinically, polysymptomatic or sensorial involvement, good prognostic factors and complete response to pulse therapy were found to be of prognostic value in conversion to MS. A greater presence of oligoclonal bands in CSF was identified in the converted group (92.8%). In terms of localization, presence of callosal lesion (71.4%), periventricular lesion (97.1%), Gd-enhanced lesion (48.6%), black hole (54.2%) and brainstem lesion (57.1%) was statistically significant in terms of conversion to MS.

Conclusion

A carefully performed neurological assessment of symptoms and signs, and evaluation of lesions on MR combined with CSF findings are important for identifying the risk of conversion to MS. This information may be useful when considering treatment in CIS patients instead of waiting for conversion to MS.

Could Proteomics Become a Future Useful Tool to Shed Light on the Mechanisms of Rare Neurodegenerative Disorders?

Very often the clinical features of rare neurodegenerative disorders overlap with those of other, more common clinical disturbances. As a consequence, not only the true incidence of these disorders is underestimated, but many patients also experience a significant delay before a definitive diagnosis. Under this scenario, it appears clear that any accurate tool producing information about the pathological mechanisms of these disorders would offer a novel context for their precise identification by strongly enhancing the interpretation of symptoms. With the advent of proteomics, detection and identification of proteins in different organs/tissues, aimed at understanding whether they represent an attractive tool for monitoring alterations in these districts, has become an area of increasing interest. The aim of this report is to provide an overview of the most recent applications of proteomics as a new strategy for identifying biomarkers with a clinical utility for the investigation of rare neurodegenerative disorders.

Intrathecal IgM index correlates with a severe disease course in multiple sclerosis: Clinical and MRI results

OBJECTIVES

Intrathecally synthesized IgM can be seen not only in the cerebrospinal fluid (CSF) in infectious and inflammatory diseases of the central nervous system, but also in that of patients with multiple sclerosis (MS). Intrathecal IgM synthesis in MS seems to be correlated with an unfavorable disease course. In one cross-sectional study, intrathecal synthesis of IgM (IgM index) was found to be correlated with cranial magnetic resonance imaging (MRI) parameters. The purpose of this study was to determine the possible relationship between the IgM index and MRI and clinical parameters.

PATIENTS AND METHODS

Eighty-one patients with MS (58 female) undergoing lumbar puncture were included in the study. Fifty-one patients had a relapsing-remitting (RR) disease course, while 30 cases were secondary progressive MS (SPMS). IgM was detected in paired CSF and serum specimens using ELISA. The IgM index was calculated using the formula CSF IgM/serum IgM: CSF albumin/serum albumin. IgM indexes higher than 0.1 were considered "increased". All patients underwent brain and whole spinal cord MRI.

RESULTS

The IgM index was normal in 43 of the 81 patients (53.1%) and increased in 38 (46.9%). A significant correlation was determined between the IgM index and Expanded Disability Status Scale (EDSS) (r=0.638, p=0.001). Most of the subjects with increased IgM indexes were SPMS patients, 28 having a SPMS course and 10 a RRMS course. Only two patients with SPMS courses had normal IgM indexes. EDSS scores were significantly higher in patients with increased IgM indexes (EDSS 4.3 vs EDSS 2.8, p=0.000). All patients with EDSS >3 had increased IgM indexes. All patients with IgM index values higher than 0.2 IgM had SPMS courses and EDSS >6. Time to onset of the secondary progressive phase of the disease was correlated with IgM index values (p=0.004). IgM index values were also correlated with T1 hypointense lesions (r=0.0431, p=0.008) and Gd enhancing lesions (r=0.0396, p=0.006). Patients with increased IgM indexes also had more spinal lesions (p=0.000). No relation was determined between an increased IgM index and an increased IgG index. No relation was determined with IgG oligoclonal band positivity. No correlation was also observed between IgM index and IgG index values.

CONCLUSION

According to our findings, intrathecal IgM synthesis is associated with a worse long-term prognosis. It also correlates with a higher relapse rate, greater disability, and worse MRI outcomes. Early observation of increased IgM index values will be a helpful tool for clinicians in selecting patients for early immunomodulatory or immunosuppressant treatments.

Role of 14-3-3 proteins in human diseases

14-3-3 proteins are a family of highly conserved small proteins. By interacting with target proteins, 14-3-3 proteins are involved in regulating multiple cellular processes, such as signal transduction, cell cycle regulation, apoptosis, cellular metabolism, cytoskeleton organization and malignant transformation. Mounting evidence suggests that 14-3-3 proteins play an important role in a wide variety of human diseases, such as human cancers and nervous system diseases. This review aims to summarize the current knowledge on the expression, regulation and biological function of 14-3-3 to highlight the role of 14-3-3 proteins in human diseases.

Quantitative proteomics reveals Piccolo as a candidate serological correlate of recovery from Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an autoimmune-mediated peripheral neuropathy of unknown cause. However, about a quarter of GBS patients have suffered a recent bacterial or viral infection, and axonal forms of the disease are especially common in these patients. Proteomics is a good methodological approach for the discovery of disease biomarkers. Until recently, most proteomics studies of GBS and other neurodegenerative diseases have focused on the analysis of the cerebrospinal fluid (CSF). However, serum represents an attractive alternative to CSF because it is easier to sample and has potential for biomarker discovery. The goal of this research was the identification of serum biomarkers associated with recovery from GBS. To address this objective, a quantitative proteomics approach was used to characterize differences in the serum proteome between a GBS patient and her healthy identical twin in order to lessen variations due to differences in genetic background, and with additional serum samples collected from unrelated GBS (N = 3) and Spinal Cord Injury (SCI) (N = 3) patients with similar medications. Proteomics results were then validated by ELISA using sera from additional GBS patients (N = 5) and healthy individuals (N = 3). All GBS and SCI patients were recovering from the acute phase of the disease. The results showed that Piccolo, a protein that is essential in the maintenance of active zone structure, constitutes a potential serological correlate of recovery from GBS. These results provided the first evidence for the Piccolo´s putative role in GBS, suggesting a candidate target for developing a serological marker of disease recovery.

Body fluid biomarkers in multiple sclerosis: how far we have come and how they could affect the clinic now and in the future

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system, which affects over 2.5 million people worldwide. Although MS has been extensively studied, many challenges still remain in regards to treatment, diagnosis and prognosis. Typically, prognosis and individual responses to treatment are evaluated by clinical tests such as the expanded disability status scale, MRI and presence of oligoclonal bands in the cerebrospinal fluid. However, none of these measures correlates strongly with treatment efficacy or disease progression across heterogeneous patient populations and subtypes of MS. Numerous studies over the past decades have attempted to identify sensitive and specific biomarkers for diagnosis, prognosis and treatment efficacy of MS. The objective of this article is to review and discuss the current literature on body fluid biomarkers in MS, including research on potential biomarker candidates in the areas of miRNA, mRNA, lipids and proteins.

Targeted quantification of C-reactive protein and cystatin c and its variants by immuno-MALDI-MS

The most common technologies for quantitative determination of protein biomarkers are immunoassays, which exist in various formats. Immunoassays offer sensitive and fast protein quantification, but can hardly discriminate between protein variants. Post-translational modifications and genetic variants increase protein microheterogeneity and may play important roles in biological processes. Mass spectrometry combined with immunoaffinity enrichment detects protein microheterogeneity and can quantify different isoforms. We here present an immuno-MALDI-MS approach for the combined quantification of two important biomarkers of inflammation and renal function, C-reactive protein (CRP) and cystatin C, respectively. Antibodies were immobilized onto reversed-phase tips, which allows easy and flexible sample processing. Quantification was performed in singleplex and duplex assays, and characteristics were evaluated for different internal standards, i.e., PEGylated and polyhistidine-tagged proteins. The best performances were obtained for polyhistidine-tagged standards with respect to limits of detection (CRP, 0.10 μg/mL; cystatin C, 0.003 μg/mL) and coefficients of variation (CRP, 2.4-7.0%; cystatin C, 3.0-8.9%). The methods were benchmarked against immunoturbidimetry and nephelometry and demonstrated good between-assay agreement (R(2) = 0.989 for CRP; R(2) = 0.939 for cystatin C). Several variants of cystatin C were identified and quantified, while none were observed for CRP. This immuno-MALDI method describes a novel approach for targeted quantitative investigation of protein microheterogeneity and is well suited for assessment of biomarker status in precious samples from biobanks due to its low sample consumption.

Exploring the human tear fluid: discovery of new biomarkers in multiple sclerosis

PURPOSE

Multiple sclerosis is the first cause of progressive neurological disability among young adults living in Western countries. Its diagnosis is mostly based on clinical evaluation, neuroimaging, and in some cases cerebrospinal fluid (CSF) analysis, but no definitive diagnostic test exists. We proposed here that the exploration of tears from multiple sclerosis patients could lead to the discovery of new biomarkers.

EXPERIMENTAL DESIGN

Thirty multiple sclerosis patients (20% men) recruited to the Geneva University Hospitals were included in our study (mean age ± SD [years]: 42.4 ± 15.9). Twenty-five control patients (32% men) were also enrolled (mean age ± SD [years]: 42.7±15.1). Tears, CSF or blood was collected for each patient. Three independent quantitative (tandem mass tag) experiments were carried out between tears from multiple sclerosis and control patients. Protein verification was performed by Western blot on tears and CSF and by ELISA on serum samples.

RESULTS

Combined proteomics analyses provided 185 identified tear proteins. Among the differential proteins, alpha-1 antichymotrypsin was the only one to be significantly increased in the three experiments with similar ratios (ratios 1.6 to 2.5, p < 0.05). Its tear, CSF and serum elevation were further confirmed by Western blot and ELISA, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

This study supports the concept that modifications of the tear proteome can reflect biological abnormalities associated with multiple sclerosis and perhaps other inflammatory conditions affecting the CNS. In addition, alpha-1 antichymotrypsin elevation in tear fluid emerges as a promising biomarker for the diagnosis of multiple sclerosis.

Clinical, MRI, and CSF markers of disability progression in multiple sclerosis

Multiple sclerosis (MS) is a chronic disorder of the central nervous system (CNS) in which the complex interplay between inflammation and neurodegeneration determines varying degrees of neurological disability. For this reason, it is very difficult to express an accurate prognosis based on purely clinical information in the individual patient at an early disease stage. Magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) biomarkers are promising sources of prognostic information with a good potential of quantitative measure, sensitivity, and reliability. However, a comprehensive MS outcome prediction model combining multiple parameters is still lacking. Current relevant literature addressing the topic of clinical, MRI, and CSF markers as predictors of MS disability progression is reviewed here.

14-3-3s are potential biomarkers for HIV-related neurodegeneration

Over the last decade, it has become evident that 14-3-3 proteins are essential for primary cell functions. These proteins are abundant throughout the body, including the central nervous system and interact with other proteins in both cell cycle and apoptotic pathways. Examination of cerebral spinal fluid in humans suggests that 14-3-3s including 14-3-3ε (YWHAE) are up-regulated in several neurological diseases, and loss or duplication of the YWHAE gene leads to Miller-Dieker syndrome. The goal of this review is to examine the utility of 14-3-3s as a marker of human immune deficiency virus (HIV)-dependent neurodegeneration and also as a tool to track disease progression. To that end, we describe mechanisms implicating 14-3-3s in neurological diseases and summarize evidence of its interactions with HIV accessory and co-receptor proteins.

Protein biomarkers for multiple sclerosis: semi-quantitative analysis of cerebrospinal fluid candidate protein biomarkers in different forms of multiple sclerosis

BACKGROUND

The complex pathogenesis of multiple sclerosis, combined with an unpredictable prognosis, requires identification of disease-specific diagnostic and prognostic biomarkers.

OBJECTIVE

To determine whether inflammatory proteins, such as neurofilament light chain, myelin oligodendrocyte glycoprotein and myelin basic protein, and neurodegenerative proteins, such as tau and glial fibrillary acidic protein, can serve as biomarkers for predicting the clinical subtype and prognosis of MS.

METHODS

Cerebrospinal fluid and serum samples were collected from patients with a diagnosis of clinically isolated syndrome (n = 46), relapsing-remitting MS (n = 67) or primary-progressive MS (n = 22) along with controls having other non-inflammatory neurological disease (n = 22). Western blot analyses were performed for the listed proteins. Protein levels were compared among different clinical subtypes using one-way analysis of variance analysis. The k-nearest neighbour algorithm was further used to assess the predictive use of these proteins for clinical subtype classification.

RESULTS

The results showed that each of tau, GFAP, MOG and NFL protein concentrations differed significantly (p < 0.001) in multiple sclerosis clinical subtypes compared with the controls. Levels of the proteins also differed between the multiple sclerosis clinical subtypes, which may be associated with the underlying disease process. Classification studies revealed that these proteins might be useful for identifying multiple sclerosis clinical subtypes.

CONCLUSIONS

We showed that select biomarkers may have potential in identifying multiple sclerosis clinical subtypes. We also showed that the predictive value of the prognosis increased when using a combination of the proteins versus using them individually.

Are cerebrospinal fluid biomarkers useful in predicting the prognosis of multiple sclerosis patients?

Multiple sclerosis (MS) is the prototypical inflammatory demyelinating disorder of the central nervous system (CNS). Although many advances have been made in the comprehension of its pathogenesis, the etiology is still unknown. The complexity of MS reflects in the extreme variability of the clinical manifestations and clinical course both between and within patients, in addition to immunopathological mechanisms and response to treatment. Several prognostic factors have been suggested in large scale studies, but predictions in individual cases are difficult to make. Cerebrospinal fluid (CSF) biomarkers, such as 14-3-3, tau, and cystatin C are promising sources of prognostic information with a good potential of quantitative measure, sensitivity, and reliability. However, none has shown sufficient reproducibility to be applied in clinical practice. Here we review the current literature addressing the above mentioned biomarkers as MS severity predictors at an early stage.

14-3-3 proteins as potential therapeutic targets

The 14-3-3 family of phosphoserine/phosphothreonine-binding proteins dynamically regulates the activity of client proteins in various signaling pathways that control diverse physiological and pathological processes. In response to environmental cues, 14-3-3 proteins orchestrate the highly regulated flow of signals through complex networks of molecular interactions to achieve well-controlled physiological outputs, such as cell proliferation or differentiation. Accumulating evidence now supports the concept that either an abnormal state of 14-3-3 protein expression, or dysregulation of 14-3-3/client protein interactions, contributes to the development of a large number of human diseases. In particular, clinical investigations in the field of oncology have demonstrated a correlation between upregulated 14-3-3 levels and poor survival of cancer patients. These studies highlight the rapid emergence of 14-3-3 proteins as a novel class of molecular target for potential therapeutic intervention. The current status of 14-3-3 modulator discovery is discussed.