Chitinases as a potential diagnostic and prognostic biomarker for amyotrophic lateral sclerosis: a systematic review and meta-analysis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the degeneration of motor neurons, and there is currently a lack of reliable diagnostic biomarkers. This meta-analysis aimed to evaluate CHIT1, CHI3L1, and CHI3L2 levels in the cerebrospinal fluid (CSF) or blood and their diagnostic potential in ALS patients. A systematic, comprehensive search was performed of peer-reviewed English-language articles published before April 1, 2023, in PubMed, Scopus, Embase, Cochrane Library, and Web of Science. After a thorough screening, 13 primary articles were included, and their chitinases-related data were extracted for systematic review and meta-analysis. In ALS patients, the CSF CHIT1 levels were significantly elevated compared to controls with healthy control (HC) (SMD, 1.92; 95% CI, 0.78 - 3.06; P < 0.001). CHIT1 levels were elevated in the CSF of ALS patients compared to other neurodegenerative diseases (ONDS) control (SMD, 0.74; 95% CI, 0.22 - 1.27; P < 0.001) and exhibited an even more substantial increase when compared to ALS-mimicking diseases (AMDS) (SMD, 1.15; 95% CI, 0.35 - 1.94, P < 0.001). Similarly, the CSF CHI3L1 levels were significantly higher in ALS patients compared to HC (SMD, 3.16; 95% CI, 1.26 - 5.06, P < 0.001). CHI3L1 levels were elevated in the CSF of ALS patients compared to ONDS (SMD, 0.75; 95% CI, 0.32 - 1.19; P = 0.017) and exhibited a more pronounced increase when compared to AMDS (SMD, 1.92; 95% CI, 0.41 - 3.42; P < 0.001). The levels of CSF chitinases in the ALS patients showed a significant increase, supporting the role of CSF chitinases as diagnostic biomarkers for ALS.

CSF chitinases before and after symptom onset in amyotrophic lateral sclerosis.

OBJECTIVE: To evaluate the CSF levels of chitinase proteins during the presymptomatic and early symptomatic phases of amyotrophic lateral sclerosis (ALS). METHODS: CSF samples were obtained from 16 controls, 55 individuals at-risk for ALS (including 18 carrying a mutation in C9ORF72, 33 in SOD1), 12 ALS patients, and 7 phenoconverters (individuals diagnosed with ALS during follow-up). At-risk individuals and phenoconverters were enrolled through the Pre-fALS study, which includes individuals carrying an ALS-associated gene mutation without disease manifestations at initial assessment. Longitudinal CSF collections, where possible, took place every 3-12 months for ALS patients and every 1-2 years for others. CSF levels of chitotriosidase 1 (CHIT1), chitinase-3-like protein 1 (CHI3L1, YKL-40) and chitinase-3-like protein 2 (CHI3L2, YKL-39) were measured by ELISA, along with CHIT1 activity. Longitudinal changes in at-risk individuals and phenoconverters were fitted to linear mixed effects models. RESULTS: Slowly rising levels of CHIT1 were observed over time in the at-risk individuals (slope 0.059 log10 [CHIT1] per year, P < 0.001). Among phenoconverters, CHIT1 levels and activity rose more sharply (0.403 log10 [CHIT1] per year, P = 0.005; 0.260 log10 [CHIT1 activity] per year, P = 0.007). Individual levels of both CHI3L1 and CHI3L2 remained relatively stable over time in all participant groups. INTERPRETATION: The CHIT1 neuroinflammatory response is a feature of the late presymptomatic to early symptomatic phases of ALS. This study does not suggest a long prodrome of upregulated glial activity in ALS pathogenesis, but strengthens the place of CHIT1 as part of a panel of biomarkers to objectively assess the impact of immune-modulatory therapeutic interventions in ALS.

Cerebrospinal Fluid YKL-40 and Chitotriosidase Levels in Frontotemporal Dementia Vary by Clinical, Genetic and Pathological Subtype.

BACKGROUND: Chronic glial dysfunction may contribute to the pathogenesis of frontotemporal dementia (FTD). Cerebrospinal fluid (CSF) levels of glia-derived proteins YKL-40 and chitotriosidase are increased in Alzheimer's disease (AD) but have not been explored in detail across the spectrum of FTD. METHODS: We investigated whether CSF YKL-40 and chitotriosidase levels differed between FTD patients and controls, across different clinical and genetic subtypes of FTD, and between individuals with a clinical FTD syndrome due to AD versus non-AD (frontotemporal lobar degeneration, FTLD) pathology (based on CSF neurodegenerative biomarkers). Eighteen healthy controls and 64 people with FTD (behavioural variant FTD, n = 20; primary progressive aphasia [PPA], n = 44: nfvPPA, n = 16, svPPA, n = 11, lvPPA, n = 14, PPA-NOS, n = 3) were included. 10/64 had familial FTD, with mutations in GRN(n = 3), MAPT(n = 4), or C9orf72 (n = 3). 15/64 had neurodegenerative biomarkers consistent with AD pathology. Levels were measured by immunoassay and compared using multiple linear regressions. We also examined relationships of YKL-40 and chitotriosidase with CSF total tau (T-tau), phosphorylated tau 181 (P-tau) and ß-amyloid 1-42 (Aß42), with each other, and with age and disease du-ration. RESULTS: CSF YKL-40 and chitotriosidase levels were higher in FTD, particularly lvPPA (both) and nfvPPA (YKL-40), compared with controls. GRN mutation carriers had higher levels of both proteins than controls and C9orf72 expansion carriers, and YKL-40 was higher in MAPT mutation carriers than controls. Individuals with underlying AD pathology had higher YKL-40 and chitotriosidase levels than both controls and those with likely FTLD pathology. CSF YKL-40 and chitotriosidase levels were variably associated with levels of T-tau, P-tau and Aß42, and with each other, depending on clinical syndrome and underlying pathology. CSF YKL-40 but not chitotriosidase was associated with age, but not disease duration. CONCLUSION: CSF YKL-40 and chitotriosidase levels are increased in individuals with clinical FTD syndromes, particularly due to AD pathology. In a preliminary analysis of genetic groups, levels of both proteins are found to be highly elevated in FTD due to GRN mutations, while YKL-40 is increased in individuals with MAPT mutations. As glia-derived protein levels generally correlate with T-tau and P-tau levels, they may reflect the glial response to neurodegeneration in FTLD.

Different CSF protein profiles in amyotrophic lateral sclerosis and frontotemporal dementia with C9orf72 hexanucleotide repeat expansion.

OBJECTIVES: The hexanucleotide repeat expansion in the C9orf72 gene is the most common mutation associated with amyotrophic lateral sclerosis (C9-ALS) and frontotemporal dementia (C9-FTD). Until now, it is unknown which factors define whether C9orf72 mutation carriers develop ALS or FTD. Our aim was to identify protein biomarker candidates in the cerebrospinal fluid (CSF) which differentiate between C9-ALS and C9-FTD and might be indicative for the outcome of the mutation. METHODS: We compared the CSF proteome of 16 C9-ALS and 8 C9-FTD patients and 11 asymptomatic C9orf72 mutation carriers (CAR) by isobaric tags for relative and absolute quantitation. Eleven biomarker candidates were selected from the pool of differentially regulated proteins for further validation by multiple reaction monitoring and single-molecule array in a larger cohort (n=156). RESULTS: In total, 2095 CSF proteins were identified and 236 proteins were significantly different in C9-ALS versus C9-FTD including neurofilament medium polypeptide (NEFM) and chitotriosidase-1 (CHIT1). Eight candidates were successfully validated including significantly increased ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1) levels in C9-ALS compared with C9-FTD and controls and decreased neuronal pentraxin receptor (NPTXR) levels in C9-FTD versus CAR. CONCLUSIONS: This study presents a deep proteomic CSF analysis of C9-ALS versus C9-FTD patients. As a proof of concept, we observed higher NEFM and CHIT1 CSF levels in C9-ALS. In addition, we also show clear upregulation of UCHL1 in C9-ALS and downregulation of NPTXR in C9-FTD. Significant differences in UCHL1 CSF levels may explain diverging ubiquitination and autophagy processes and NPTXR levels might reflect different synapses organisation processes.

Diagnostic-prognostic value and electrophysiological correlates of CSF biomarkers of neurodegeneration and neuroinflammation in amyotrophic lateral sclerosis.

Neurofilament light chain protein (NfL) is currently the most accurate cerebrospinal fluid (CSF) biomarker in amyotrophic lateral sclerosis (ALS) in terms of both diagnostic and prognostic value, but the mechanism underlying its increase is still a matter of debate. Similarly, emerging CSF biomarkers of neurodegeneration and neuroinflammation showed promising results, although further studies are needed to clarify their clinical and pathophysiological roles. In the present study we compared the diagnostic accuracy of CSF NfL, phosphorylated (p)-tau/total (t)-tau ratio, chitinase-3-like protein 1 (YKL-40) and chitotriosidase 1 (CHIT1), in healthy controls (n = 43) and subjects with ALS (n = 80) or ALS mimics (n = 46). In ALS cases, we also investigated the association between biomarker levels and clinical variables, the extent of upper motor neuron (UMN) and lower motor neuron (LMN) degeneration, and denervation activity through electromyography (EMG). ALS patients showed higher levels of CSF NfL, YKL-40, CHIT1, and lower values of p-tau/t-tau ratio compared to both controls and ALS mimics. Among all biomarkers, NfL yielded the highest diagnostic performance (> 90% sensitivity and specificity) and was the best predictor of disease progression rate and survival in ALS. NfL levels showed a significant  correlation with the extent of LMN involvement, whereas YKL-40 levels increased together with the number of areas showing both UMN and LMN damage. EMG denervation activity did not correlate with any CSF biomarker change. These findings confirm the highest value of NfL among currently available CSF biomarkers for the diagnostic and prognostic assessment of ALS and contribute to the understanding of the pathophysiological and electrophysiological correlates of biomarker changes.

CHIT1 at Diagnosis Reflects Long-Term Multiple Sclerosis Disease Activity.

OBJECTIVE: Evidence for a role of microglia in the pathogenesis of multiple sclerosis (MS) is growing. We investigated association of microglial markers at time of diagnostic lumbar puncture (LP) with different aspects of disease activity (relapses, disability, magnetic resonance imaging parameters) up to 6 years later in a cohort of 143 patients. METHODS: In cerebrospinal fluid (CSF), we measured 3 macrophage and microglia-related proteins, chitotriosidase (CHIT1), chitinase-3-like protein 1 (CHI3L1 or YKL-40), and soluble triggering receptor expressed on myeloid cells 2 (sTREM2), as well as a marker of neuronal damage, neurofilament light chain (NfL), using enzyme-linked immunosorbent assay and electrochemiluminescence. We investigated the same microglia-related markers in publicly available RNA expression data from postmortem brain tissue. RESULTS: CHIT1 levels at diagnostic LP correlated with 2 aspects of long-term disease activity after correction for multiple testing. First, CHIT1 increased with reduced tissue integrity in lesions at a median 3 years later (p = 9.6E-04). Second, CHIT1 reflected disease severity at a median 5 years later (p = 1.2E-04). Together with known clinical covariates, CHIT1 levels explained 12% and 27% of variance in these 2 measures, respectively, and were able to distinguish slow and fast disability progression (area under the curve = 85%). CHIT1 was the best discriminator of chronic active versus chronic inactive lesions and the only marker correlated with NfL (r = 0.3, p = 0.0019). Associations with disease activity were, however, independent of NfL. INTERPRETATION: CHIT1 CSF levels measured during the diagnostic LP reflect microglial activation early on in MS and can be considered a valuable prognostic biomarker for future disease activity. ANN NEUROL 2020;87:633-645.

Cross-sectional and longitudinal measures of chitinase proteins in amyotrophic lateral sclerosis and expression of CHI3L1 in activated astrocytes.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a complex disease with numerous pathological mechanisms resulting in a heterogeneous patient population. Using biomarkers for particular disease mechanisms may enrich a homogeneous subset of patients. In this study, we quantified chitotriosidase (Chit-1) and chitinase-3-like protein 1 (CHI3L1), markers of glial activation, in cerebrospinal fluid (CSF) and plasma and determined the cell types that express CHI3L1 in ALS. METHODS: Immunoassays were used to quantify Chit-1, CHI3L1 and phosphorylated neurofilament heavy chain levels in longitudinal CSF and matching plasma samples from 118 patients with ALS, 17 disease controls (DCs), and 24 healthy controls (HCs). Immunostaining was performed to identify and quantify CHI3L1-positive cells in tissue sections from ALS, DCs and non-neurological DCs. RESULTS: CSF Chit-1 exhibited increased levels in ALS as compared with DCs and HCs. CSF CHI3L1 levels were increased in ALS and DCs compared with HCs. No quantitative differences were noted in plasma for either chitinase. Patients with ALS with fast-progressing disease exhibited higher levels of CSF Chit-1 and CHI3L1 than patients with slow-progressing disease. Increased numbers of CHI3L1-positive cells were observed in postmortem ALS motor cortex as compared with controls, and these cells were identified as a subset of activated astrocytes located predominately in the white matter of the motor cortex and the spinal cord. CONCLUSIONS: CSF Chit-1 and CHI3L1 are significantly increased in ALS, and CSF Chit-1 and CHI3L1 levels correlate to the rate of disease progression. CHI3L1 is expressed by a subset of activated astrocytes predominately located in white matter.

Association between APOE4 and biomarkers in cerebral adrenoleukodystrophy.

Cerebral adrenoleukodystrophy (cALD) is an inflammatory neurodegenerative disease associated with mutation of the ABCD1 gene. Proteomic analysis of cerebral spinal fluid (CSF) from young males with active cALD revealed markers of inflammation including APOE4. APOE4 genotype has been associated with an inferior prognosis following acute and chronic neurologic injury. We assessed APOE4 inheritance among 83 consecutive young males with cALD prior to hematopoietic cell transplant and its association with markers of cerebral disease. The allele frequency of APOE4 was not significantly different from that of the general population at 17%. Young males with cALD that were APOE4 carriers had similar CSF protein and chitotriosidase activity to that of non-carriers. In contrast, APOE4 carriers had an increased burden of cerebral disease involvement as determined by MRI severity score (10.5 vs 7.0 points, p = 0.01), higher gadolinium intensity score (2.0 vs 1.3 points, p = 0.007), inferior neurologic function (neurologic function score 2.4 vs 1.0, p = 0.001), and elevated CSF MMP2 levels compared to that of non-carriers (13168 vs 9472 pg/mL, p = 0.01). These are the first data showing that APOE4 is associated with increased severity of cerebral disease in cALD and suggest it may be a modifier of disease.

CSF chitinase proteins in amyotrophic lateral sclerosis.

OBJECTIVE: To evaluate the classifier performance, clinical and biochemical correlations of cerebrospinal fluid (CSF) levels of the chitinase proteins Chitotriosidase-1 (CHIT1), Chitinase-3-like protein 1 (CHI3L1) and Chitinase-3-like protein 2 (CHI3L2) in amyotrophic lateral sclerosis (ALS). METHODS: CSF levels of CHIT1, CHI3L1, CHI3L2, phosphorylated neurofilament heavy chain (pNFH) and C-reactive protein were measured by ELISA in a longitudinal cohort of patients with ALS (n=82), primary lateral sclerosis (PLS, n=10), ALS-mimic conditions (n=12), healthy controls (n=25) and asymptomatic carriers of ALS-causing genetic mutations (AGC; n=5). RESULTS: CSF CHIT1, CHI3L1 and CHI3L2 were elevated in patients with ALS compared with healthy controls (p<0.001) and ALS-mimics (CHIT1, p<0.001; CHI3L1, p=0.017; CHI3L2, p<0.001). CHIT1 and CHI3L2 were elevated in ALS compared with PLS (CHIT1, p=0.021; CHI3L1, p=0.417; CHI3L2, p<0.001). Chitinase levels were similar in AGCs and healthy controls. Chitinase proteins distinguished ALS from healthy controls (area under the curve (AUC): CHIT1 0.92; CHI3L1 0.80; CHI3L2 0.90), mimics (AUC: CHIT1 0.84; CHI3L1 0.73; CHI3L2 0.88) and, to a lesser extent, PLS (AUC: CHIT 0.73; CHI3L1 0.51; CHI3L2 0.82) but did not outperform pNFH. CHIT1 and CHI3L2 correlated with disease progression rate (Pearson's r=0.49, p<0.001; r=0.42, p<0.001, respectively). CHI3L1 correlated with degree of cognitive dysfunction (r=-0.25, p=0.038). All chitinases correlated with pNFH. CHIT1 levels were associated with survival in multivariate models. Chitinase levels were longitudinally stable. CONCLUSIONS: CSF chitinase proteins may have limited value as independent diagnostic and stratification biomarkers in ALS, but offer a window into non-autonomous mechanisms of motor neuronal loss in ALS, specifically in assessing response to therapies targeting neuroinflammatory pathways.

Different neuroinflammatory profile in amyotrophic lateral sclerosis and frontotemporal dementia is linked to the clinical phase.

OBJECTIVE: To investigate the role of neuroinflammation in asymptomatic and symptomatic amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mutation carriers. METHODS: The neuroinflammatory markers chitotriosidase 1 (CHIT1), YKL-40 and glial fibrillary acidic protein (GFAP) were measured in cerebrospinal fluid (CSF) and blood samples from asymptomatic and symptomatic ALS/FTD mutation carriers, sporadic cases and controls by ELISA. RESULTS: CSF levels of CHIT1, YKL-40 and GFAP were unaffected in asymptomatic mutation carriers (n=16). CHIT1 and YKL-40 were increased in gALS (p<0.001, n=65) whereas GFAP was not affected. Patients with ALS carrying a CHIT1 polymorphism had lower CHIT1 concentrations in CSF (-80%) whereas this polymorphism had no influence on disease severity. In gFTD (n=23), increased YKL-40 and GFAP were observed (p<0.05), whereas CHIT1 was nearly not affected. The same profile as in gALS and gFTD was observed in sALS (n=64/70) and sFTD (n=20/26). CSF and blood concentrations correlated moderately (CHIT1, r=0.51) to weak (YKL-40, r=0.30, GFAP, r=0.39). Blood concentrations of these three markers were not significantly altered in any of the groups except CHIT1 in gALS of the Ulm cohort (p<0.05). CONCLUSION: Our data indicate that neuroinflammation is linked to the symptomatic phase of ALS/FTD and shows a similar pattern in sporadic and genetic cases. ALS and FTD are characterised by a different neuroinflammatory profile, which might be one driver of the diverse presentations of the ALS/FTD syndrome.

Evaluation of Chitotriosidase and CC-Chemokine Ligand 18 as Biomarkers of Microglia Activation in Amyotrophic Lateral Sclerosis.

BACKGROUND: The development of biomarkers for use in diagnosing, monitoring disease progression and analyzing therapeutic trials response in amyotrophic lateral sclerosis (ALS) is essential. OBJECTIVE: The aim of this study was to identify inflammatory factors in plasma or cerebrospinal fluid (CSF) from patients with ALS with particular attention to specific markers of microglia activation as chitotriosidase (ChT) and chemokine (C-C motif) ligand 18 (CCL18) to determine its potential as ALS biomarkers. METHODS: We studied CSF and plasma samples from 32 patients and 42 healthy controls. We assayed the ChT activity by a spectrofluorometric method and protein levels of other inflammatory -biomarkers (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6 and CCL18) by enzyme-linked immunosorbent assay. CHIT1 gene polymorphism in exon 10 (c.1049_1072dup24) encoding inactive ChT enzyme was genotyped in all subjects. RESULTS: ChT activity and TNF-alpha protein levels were significantly higher in CSF of ALS patients, but we found no correlation with the severity and progression of the disease. Nevertheless, we did not found any differences in CCL18 or IL-6 protein levels between both groups in CSF or plasma. In our sample, only 3% of subjects were homozygous carriers for the CHIT1 exon 10 duplication associated with defective enzyme. CONCLUSIONS: High ChT activity in CSF of patients with ALS may reflect microglia activation and could be a potential biomarker of the disease. We did not find any significant difference regarding CCL-18, another specific marker of microglia activation that is related with M2-like microglia phenotype. Deepening the understanding of the activation state of microglia (M1 and M2) may contribute to the knowledge about the specific role of neuroinflammation in ALS and future therapeutic strategies.

Assessment of a multiple biomarker panel for diagnosis of amyotrophic lateral sclerosis.

BACKGROUND: The aim of the study was to assess a panel of promising biomarkers for their ability to improve diagnosis of sporadic amyotrophic lateral sclerosis (ALS). METHODS: Forty patients with sporadic ALS and 40 controls with other neurological diseases were evaluated. Levels of phosphorylated neurofilament heavy chain (pNfH), S100-ß, cystatin C, and chitotriosidase (CHIT) in cerebrospinal fluid were assayed using two-site solid-phase sandwich ELISA. RESULTS: Patients with sporadic ALS showed higher levels of pNfH and CHIT than controls, but lower levels of cystatin C. Multivariate logistic regression that adjusted for patient age and sex identified significant associations between sporadic ALS and levels of pNfH, CHIT and cystatin C. Levels of pNfH correlated positively with rate of progression and decline based on the Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised. Based on receiver operating curve analysis, a pNfH cut-off of 437 ng/L discriminated patients from controls with a sensitivity of 97.3 % and specificity of 83.8 %. A CHIT cut-off of 1593.779 ng/L discriminated patients from controls with a sensitivity of 83.8 % and specificity of 81.1 %. Combining the two biomarkers gave a sensitivity of 83.8 % and specificity of 91.9 %. CONCLUSIONS: Levels of pNfH in cerebrospinal fluid may be a reliable biomarker for diagnosing ALS, and combining this biomarker with levels of CHIT may improve diagnostic accuracy.

Cerebrospinal fluid chitinase-3-like 2 and chitotriosidase are potential prognostic biomarkers in early multiple sclerosis.

BACKGROUND AND PURPOSE: The role of chitinases and chitinase-like proteins in multiple sclerosis (MS) is currently unknown; however, cerebrospinal fluid (CSF) levels of chitinase 3-like 1 (CHI3L1) predict prognosis in early MS. Whether this applies to other chitinases and chitinase-like proteins is yet to be established. Our objective was to investigate the potential of chitinase 3-like 2 (CHI3L2) and chitotriosidase as prognostic biomarkers in optic neuritis (ON) as the first demyelinating episode and to evaluate the ability of CHI3L2 to predict long-term MS risk and disability. METHODS: In a prospective cohort of 73 patients with ON as a first demyelinating episode and 26 age-matched healthy controls levels of CHI3L2 and chitotriosidase in CSF were explored by enzyme-linked immunosorbent assay. Associations with magnetic resonance imaging white matter lesions, CSF oligoclonal bands, immunoglobulin G index and leukocyte count were investigated. Long-term MS risk and disability (Expanded Disability Status Scale, Multiple Sclerosis Functional Composite components) were examined in a retrospective cohort of 78 patients with ON as the first demyelinating episode (mean follow-up 14 years). The predictive ability of CHI3L2 was compared with CHI3L1. RESULTS: Cerebrospinal fluid levels of CHI3L2 and chitotriosidase were significantly elevated in patients with ON and were associated with MS risk measures. CHI3L2 levels predicted MS development after ON (hazard ratio 1.95, P = 0.00039, Cox regression) and cognitive impairment by the Paced Auditory Serial Addition Test (P = 0.0357, linear regression) at follow-up. In a multivariate analysis of MS risk, CHI3L2 performed better than CHI3L1. CONCLUSIONS: CHI3L2 and chitotriosidase are promising biomarkers in patients with a first demyelinating episode. Our findings thus support a role for these proteins as biomarkers in early MS.

Diagnosis of neurosarcoidosis--necessity of biopsy.

INTRODUCTION: Sarcoidosis can affect any part of the central nervous system presenting with an extremely diverse clinical picture. Clinical presentations actually depend on the localization ofgranulomas in the central nervous system. Making diagnosis according to the localization and the clinical variations is often a clinical challenge. DIAGNOSIS OF NEUROSARCOIDOSIS: Diagnosis is based on the clinical picture, clinical and radiological findings (magnetic resonance imaging with contrast endocranium), laboratory findings (angio-tenzin-converting enzyme and chitotriosidase in cerebrospinal fluid); however, it is necessary first to exclude all other possible causes of granulomatous inflammation. Recent studies in patients with neurosarcoidosis show a high value of at least one marker of the disease. The safest way and the gold standard in diagnosing this disease would be histopathological confirmation, which is rarely performed due to its invasiveness. CONCLUSION: New diagnostic methods will contribute to better methods of bypassing invasive procedures, and they will significantly facilitate the diagnosis of neurosarcoidosis, which is a real challenge even for experienced clinicians who deal with this disease.

Extreme stability of chitotriosidase in cerebrospinal fluid makes it a suitable marker for microglial activation in clinical trials.

Microglia is thought to be important in Alzheimer's disease. Therefore, our aim was to investigate the usefulness of the microglial marker chitotriosidase in clinical trials. Chitotriosidase was analyzed in cerebrospinal fluid from Alzheimer's disease patients on acetylcholine esterase inhibitors (AChEI) and in cerebrospinal fluid from multiple sclerosis patients before and after natalizumab treatment. Chitotriosidase activity was extremely stable during treatment with the non-inflammatory drug AChEI. However, the immunomodulatory treatment with natalizumab led to lower chitotriosidase activity. Thus, chitotriosidase may be useful in clinical trials where microglia is targeted or as a safety biomarker in other trials where the brain is a bystander organ.

Chitinase enzyme activity in CSF is a powerful biomarker of Alzheimer disease.

OBJECTIVE: DNA damage accumulation in brain is associated with the development of Alzheimer disease (AD), but newly identified protein markers of DNA damage have not been evaluated in the diagnosis of AD and other forms of dementia. METHODS: Here, we analyzed the level of novel biomarkers of DNA damage and telomere dysfunction (chitinase activity, N-acetyl-glucosaminidase activity, stathmin, and EF-1α) in CSF of 94 patients with AD, 41 patients with non-AD dementia, and 40 control patients without dementia. RESULTS: Enzymatic activity of chitinase (chitotriosidase activity) and stathmin protein level were significantly increased in CSF of patients with AD and non-AD dementia compared with that of no dementia control patients. As a single marker, chitinase activity was most powerful for distinguishing patients with AD from no dementia patients with an accuracy of 85.8% using a single threshold. Discrimination was even superior to clinically standard CSF markers that showed an accuracy of 78.4% (ß-amyloid) and 77.6% (tau). Combined analysis of chitinase with other markers increased the accuracy to a maximum of 91%. The biomarkers of DNA damage were also increased in CSF of patients with non-AD dementia compared with no dementia patients, and the new biomarkers improved the diagnosis of non-AD dementia as well as the discrimination of AD from non-AD dementia. CONCLUSIONS: Taken together, the findings in this study provide experimental evidence that DNA damage markers are significantly increased in AD and non-AD dementia. The biomarkers identified outperformed the standard CSF markers for diagnosing AD and non-AD dementia in the cohort investigated.

Cerebrospinal fluid microglial markers in Alzheimer's disease: elevated chitotriosidase activity but lack of diagnostic utility.

Activated microglial cells, which are the resident macrophages of the central nervous system, surround amyloid ß-plaques in Alzheimer's disease (AD) brains. Inflammation including microglial activation may contribute in AD pathogenesis, and biomarkers for this process may thus be of value to study AD pathogenesis and might facilitate development of therapies targeting these cells. We therefore examined cerebrospinal fluid (CSF) biomarkers in patients with AD, other dementias, mild cognitive impairment and in healthy controls. Samples were analyzed for markers with known association to macrophage activity, including chitotriosidase, YKL-40 (CHI3L1, HC gp-39) and chemokine CC motif ligand 2 (CCL2, MCP1). Patients with AD had higher chitotriosidase activity than controls and patients with stable mild cognitive impairment, consistent with the presence of activated microglial cells in AD brains, but with large overlaps between groups. CCL2 and YKL-40 concentrations did not differ among groups. Microglial markers are unlikely to be useful for AD diagnosis, but might be useful for identification of distinct subgroups of patients, and for the development and implementation of drugs targeting microglial pathology.

Chitinase effects on immune cell response in neuromyelitis optica and multiple sclerosis.

BACKGROUND: Recent studies conducted in arthritis, asthma, and inflammatory bowel disease suggest that chitinases are important in inflammatory processes and tissue remodeling. OBJECTIVE: To investigate the role of chitinases in multiple sclerosis (MS) and neuromyelitis optica (NMO). METHODS: Levels of chitotriosidase, acid mammalian chitinase (AMCase), and chitinase 3-like-1 (CHI3L1) were measured using ELISA, in cerebrospinal fluid (CSF) and in serum from 24 patients with relapsing remitting (RR) MS, 24 patients with secondary progressive (SP) MS, 12 patients with NMO, 24 patients with other inflammatory neurological diseases (OIND), and 24 healthy controls (HCs). The number of anti-MOG cytokine-secreting cells was studied using ELISPOT. Eotaxins, MCP-1, RANTES, and IL-8 were assessed using ELISA. Cell transmigration was determined using an in vitro blood-brain barrier (BBB) model, in the presence and absence of chitinases. RESULTS: CSF chitinase levels were significantly increased in patients with RRMS and NMO compared with HCs and patients with SPMS and OIND. In contrast, no significant differences were detected in serum chitinase levels between groups. Chitinase CSF levels showed correlation with anti-MOG IL-13-producing cells, and eotaxin levels. In vitro experiments showed macrophage chitinase secretion was significantly increased by IL-13, but not by IL-5, IL-6, IL-12, or IFN-γ. Moreover, chitinases enhanced IL-8, RANTES, MCP-1, and eotaxin production, increasing migratory capacity in eosinophils, T cells, and macrophages across an in vitro BBB model. CONCLUSIONS: Chitinases increased in the CSF from patients with NMO in response to IL-13. These enhanced levels could contribute to central nervous system inflammation by increasing immune cell migration across the BBB.