Cerebrospinal Fluid Progranulin Levels Research Articles

Progranulin AAV gene therapy for frontotemporal dementia: translational studies and phase 1/2 trial interim results

GRN mutations cause progranulin haploinsufficiency, which eventually leads to frontotemporal dementia (FTD-GRN). PR006 is an investigational gene therapy delivering the granulin gene (GRN) using an adeno-associated virus serotype 9 (AAV9) vector. In non-clinical studies, PR006 transduced neurons derived from induced pluripotent stem cells of patients with FTD-GRN, resulted in progranulin expression and improvement of lipofuscin, lysosomal and neuroinflammation pathologies in Grn-knockout mice, and was well tolerated except for minimal, asymptomatic dorsal root ganglionopathy in non-human primates. We initiated a first-in-human phase 1/2 open-label trial. Here we report results of a pre-specified interim analysis triggered with the last treated patient of the low-dose cohort (n = 6) reaching the 12-month follow-up timepoint. We also include preliminary data from the mid-dose cohort (n = 7). Primary endpoints were safety, immunogenicity and change in progranulin levels in cerebrospinal fluid (CSF) and blood. Secondary endpoints were Clinical Dementia Rating (CDR) plus National Alzheimer’s Disease Coordinating Center (NACC) Frontotemporal Lobar Degeneration (FTLD) rating scale and levels of neurofilament light chain (NfL). One-time administration of PR006 into the cisterna magna was generally safe and well tolerated. All patients developed treatment-emergent anti-AAV9 antibodies in the CSF, but none developed anti-progranulin antibodies. CSF pleocytosis was the most common PR006-related adverse event. Twelve serious adverse events occurred, mostly unrelated to PR006. Deep vein thrombosis developed in three patients. There was one death (unrelated) occurring 18 months after treatment. CSF progranulin increased after PR006 treatment in all patients; blood progranulin increased in most patients but only transiently. NfL levels transiently increased after PR006 treatment, likely reflecting dorsal root ganglia toxicity. Progression rates, based on the CDR scale, were within the broad ranges reported for patients with FTD. These data provide preliminary insights into the safety and bioactivity of PR006. Longer follow-up and additional studies are needed to confirm the safety and potential efficacy of PR006. ClinicalTrials.gov identifier: NCT04408625.

Phase 1 study of latozinemab in progranulin-associated frontotemporal dementia.

Heterozygous mutations in the GRN gene lead to reduced progranulin (PGRN) levels in plasma and cerebrospinal fluid (CSF) and are causative of frontotemporal dementia (FTD) with > 90% penetrance. Latozinemab is a human monoclonal immunoglobulin G1 antibody that is being developed to increase PGRN levels in individuals with FTD caused by heterozygous loss-of-function GRN mutations. A first-in-human phase 1 study was conducted to evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of multiple-dose intravenous administration of latozinemab in eight symptomatic participants with FTD caused by a heterozygous loss-of-function GRN mutation (FTD-GRN). Latozinemab demonstrated favorable safety and PK/PD profiles. Multiple-dose administration of latozinemab increased plasma and CSF PGRN levels in participants with FTD-GRN to levels that approximated those seen in healthy volunteers. Data from the first-in-human phase 1 study support further development of latozinemab for the treatment of FTD-GRN. GRN mutations decrease progranulin (PGRN) and cause frontotemporal dementia (FTD).Latozinemab is being developed as a PGRN-elevating therapy.Latozinemab demonstrated a favorable safety profile in a phase 1 clinical trial.Latozinemab increased PGRN levels in the CNS of symptomatic FTD-GRN participants.

Repeat IV and SC Dosing of the Anti-Sortilin Antibody AL101 (P7-6.007)

<h3>Objective:</h3> To investigate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of AL101 following repeated intravenous (IV) or subcutaneous (SC) administration. <h3>Background:</h3> Variants in <i>GRN</i>, the coding gene for progranulin (PGRN), have been implicated in a number of neurodegenerative disorders, including frontotemporal dementia, Alzheimer’s disease, and Parkinson’s disease. Sortilin, expressed on neurons and microglia, is a key regulator of PGRN levels through sortilin-mediated degradation. Increasing PGRN levels may reduce rates of neuronal loss and clinical decline in neurodegeneration. AL101 is a human IgG1 monoclonal antibody that decreases sortilin and increases PGRN levels in preclinical models and in single-dosed healthy volunteers, and is being developed for neurodegenerative disorders. <h3>Design/Methods:</h3> Healthy volunteers received repeat doses of AL101 in two cohorts: 300 mg SC q2w for a total of 7 doses and 30 mg/kg IV q4w for a total of 4 doses. Safety measures and PK/PD markers in plasma and cerebrospinal fluid (CSF) were assessed at up to 16 and 20 weeks for SC and IV cohorts, respectively. <h3>Results:</h3> Adverse events were generally mild to moderate in severity and self-limiting, consistent with preliminary single-dose AL101 data. There were no severe or serious adverse events related to repeat-dose administration. Subjects in the SC repeat-dose cohort reported a higher number of overall injection site reactions that were mild in severity. Repeat-dose AL101 increased CSF PGRN levels of healthy volunteers up to approximately 80% above baseline. PK/PD modeling based on data from these repeat-dose cohorts supports dosing intervals of up to q8w. <h3>Conclusions:</h3> Repeat IV or SC administration of AL101 is generally safe and well tolerated. AL101 is a potent modulator of PGRN levels in the CSF, with a PK/PD profile that supports its further development in neurodegenerative diseases. <b>Disclosure:</b> Dr. Park has received personal compensation for serving as an employee of Alector. Dr. Park has received personal compensation for serving as an employee of Supernus Pharmaceuticals. Dr. Park has stock in Alector. Dr. Maslyar has received personal compensation for serving as an employee of Alector. Dr. Maslyar has stock in Alector. Michael Ward has received personal compensation for serving as an employee of Alector. Michael Ward has stock in Alector. Michael Ward has received intellectual property interests from a discovery or technology relating to health care. Michael Ward has a non-compensated relationship as a Reviewer with ADDF that is relevant to AAN interests or activities. Dr. Yeh has received stock or an ownership interest from Alector. Dr. Yeh has received stock or an ownership interest from Genentech. Dr. Yeh has received personal compensation in the range of $100,000-$499,999 for serving as a Scientist with Genentech. Dr. Yeh has received personal compensation in the range of $100,000-$499,999 for serving as a Head of Biomarkers with Alector. Hua Long has received personal compensation for serving as an employee of Alector. Hua Long has received stock or an ownership interest from Alector. Hua Long has received intellectual property interests from a discovery or technology relating to health care. Michael Kurnellas has received personal compensation for serving as an employee of Alector. Michael Kurnellas has received stock or an ownership interest from Alector. Michael Kurnellas has received intellectual property interests from a discovery or technology relating to health care. Ms. Vadhavkar has received personal compensation for serving as an employee of Alector. Ms. Vadhavkar has received personal compensation for serving as an employee of Ardelyx. Ms. Vadhavkar has stock in Alector. Ms. Vadhavkar has stock in Ardelyx. Dr. Budda has received personal compensation for serving as an employee of Alector. Dr. Budda has received personal compensation for serving as an employee of Acceleron Pharma. Dr. Budda has stock in Alector. Dr. Budda has stock in Acceleron Pharma.

AL001 restores CSF PGRN levels and normalizes disease‐associated biomarkers in individuals with frontotemporal dementia due to heterozygous mutations in the progranulin gene

AbstractBackgroundAL001 is a recombinant humanized anti‐Sortilin monoclonal antibody in development for frontotemporal dementia (FTD). Mutations in a single copy of the progranulin gene (GRN) leads to a 50% or greater decrease in the level of circulating progranulin (PGRN) protein levels and are causative of FTD. The disease is associated with increased inflammation and impaired lysosomal function in the brain. The INFRONT Phase 1/1b clinical study AL001‐1 investigated the safety, tolerability, pharmacokinetics and pharmacodynamics of intravenously administered AL001 in healthy volunteers (HV) and participants with a GRN mutation causative of FTD (FTD‐GRN). In addition, the study investigated the effect of AL001 on disease‐associated biomarkers.MethodA total of 64 participants were enrolled in the AL001‐1 study. In the single dose ascending part of the study, 50 healthy volunteer participants were enrolled with 38 exposed to AL001 and 12 exposed to placebo. The study enrolled 6 asymptomatic FTD‐GRN and 8 symptomatic FTD‐GRN participants. The 8 symptomatic FTD‐GRN participants received 3 doses of 30 mg/kg of AL001 over 4 weeks.ResultTreatment of symptomatic FTD‐GRN participants with AL001 over 4 weeks restored PGRN levels in the cerebrospinal fluid (CSF) to normal levels for more than 8 weeks. To further investigate the effects of restoring PGRN levels, partial normalization of a FTD disease proteomic signature was observed in the CSF 4 weeks after the last dose in multidose treatment group. Compared to healthy volunteers, AL001 treatment rescued cathepsin B (CTSB), a marker of lysosomal function, by 58%. AL001 treatment also partially normalized markers of inflammation and gliosis, osteopontin (SPP1) and chitotriosidase (CHIT1) by 52% and 22%, respectively. In addition to the reversal of these disease phenotypes, a 14% reduction (n.s.) in plasma neurofilament light chain (NfL), a marker of neuron injury and stress, was observed after 8 weeks after the last dose.ConclusionAL001 treatment resulted in a sustained increase in plasma and CSF PGRN in FTD‐GRN mutation carriers. New data showed reduction of NfL and normalization of proteins associated with the disease after one month of dosing. These results have supported progressing AL001 to Phase 2 and pivotal Phase 3 studies.

A Highly Sensitive Sandwich ELISA to Detect CSF Progranulin: A Potential Biomarker for CNS Disorders.

Progranulin (PGRN) plays critical roles in inflammation, tumorigenesis, and neurodegeneration. PGRN levels in blood and cerebrospinal fluid (CSF) are being increasingly investigated as potential biomarkers for these disorders. However, the value of CSF PGRN as a biomarker has been limited because currently available commercial enzyme-linked immunosorbent assay (ELISA) kits have suboptimal sensitivity for detecting CSF PGRN. In this study, pairs of monoclonal antibodies (MAbs) were first screened from eleven monoclonal antiPGRN antibodies using indirect ELISA, then a sandwich ELISA was established using the 2 optimized MAbs. This system displayed high sensitivity, with a lower limit of detection of 60.0 pg/mL and a lower limit of quantification of 150 pg/mL. By using this ELISA system, we showed varied CSF PGRN levels in different brain disorders. For example, as compared with the normal controls, patients with Alzheimer disease or multiple sclerosis showed mildly increased CSF PGRN; those with aseptic encephalitis or neuropsychiatric systemic lupus erythematosus showed moderately increased CSF PGRN; those with bacterial leptomeningitis showed severely increased CSF PGRN. Additionally, determining CSF PGRN levels could monitor CNS metastasis and CSF seeding of carcinomas. These results indicate that this system can be valuable in studying the diagnostic and prognostic value of CSF PGRN in brain disorders.

CSF-Progranulin and Neurofilament Light Chain Levels in Patients With Radiologically Isolated Syndrome-Sign of Inflammation.

Background: Cerebrospinal fluid (CSF) markers of disease in patients with radiologically isolated syndrome (RIS) are the subject of intense investigation, because they have the potential to enhance our understanding of the natural disease course and provide insights into similarities and differences between RIS and other multiple sclerosis (MS) disease identities.Methods: Here we compared neurofilament light chain (NFL) and progranulin (PGRN) levels in the CSF in RIS patients with levels in patients with different subtypes of MS and healthy controls (HC) using Kruskal–Wallis one-way analysis of variance.Results: Median CSF NFL concentrations in RIS patients did not differ to those in HC and clinically isolated syndrome (CIS) patients, but were significantly lower than in relapsing remitting (RRMS) and primary progressive (PPMS) MS patients. In contrast, RIS patients exhibited higher median CSF PGRN levels than HC and showed no significant differences compared with CIS, RRMS, and PPMS cases.Conclusion: We postulate that elevated PGRN values in the CSF of RIS patients might indicate inflammatory and repair activity prior to axonal disintegration.

Diagnostic value of cerebrospinal fluid tau, neurofilament, and progranulin in definite frontotemporal lobar degeneration

BackgroundWe explored the diagnostic performance of cerebrospinal fluid (CSF) biomarkers in allowing differentiation between frontotemporal lobar degeneration (FTLD) and Alzheimer’s disease (AD), as well as between FTLD pathological subtypes.MethodsCSF levels of routine AD biomarkers (phosphorylated tau (p-tau181), total tau (t-tau), and amyloid-beta (Aβ)1–42) and neurofilament proteins, as well as progranulin levels in both CSF and serum were quantified in definite FTLD (n = 46), clinical AD (n = 45), and cognitively healthy controls (n = 20). FTLD subgroups were defined by genetic carrier status and/or postmortem neuropathological confirmation (FTLD-TDP: n = 34, including FTLD-C9orf72: n = 19 and FTLD-GRN: n = 9; FTLD-tau: n = 10).ResultsGRN mutation carriers had significantly lower progranulin levels compared to other FTLD patients, AD, and controls. Both t-tau and p-tau181 were normal in FTLD patients, even in FTLD-tau. Aβ1–42 levels were very variable in FTLD. Neurofilament light chain (Nf-L) was significantly higher in FTLD compared with AD and controls. The reference logistic regression model based on the established AD biomarkers could be improved by the inclusion of CSF Nf-L, which was also important for the differentiation between FTLD and controls. Within the FTLD cohort, no significant differences were found between FTLD-TDP and FTLD-tau, but GRN mutation carriers had higher t-tau and Nf-L levels than C9orf72 mutation carriers and FTLD-tau patients.ConclusionsThere is an added value for Nf-L in the differential diagnosis of FTLD. Progranulin levels in CSF depend on mutation status, and GRN mutation carriers seem to be affected by more severe neurodegeneration.

Higher levels of progranulin in cerebrospinal fluid of patients with lymphoma and carcinoma with CNS metastasis.

Assessing central nervous system (CNS) involvement in patients with lymphoma or carcinoma is important in determining therapy and prognosis. Progranulin (PGRN) is a secreted glycosylated protein with roles in cancer growth and survival; it is highly expressed in aggressive cancer cell lines and specimens from many cancer types. We examined PRGN levels by Enzyme Immuno-Assay (EIA) in cerebrospinal fluid (CSF) samples from 230 patients, including 18 with lymphoma [12 with CNS metastasis (CNS+); 6 without CNS metastasis (CNS-)], 21 with carcinomas (10 CNS+; 11 CNS-), and 191 control patients with non-cancer neurological diseases, and compared PRGN levels among these disease groups. Median CSF PGRN levels in the CNS+ lymphoma group were significantly higher than in the CNS- lymphoma and control non-cancer groups; and were also significantly higher in the CNS+ carcinoma group than in the CNS- carcinoma and control groups, except for patients with infectious neurological disorders. Receiver operating characteristic curve analyses revealed that CSF PGRN levels distinguished CNS+ lymphoma from CNS- lymphoma and non-cancer neurological diseases [area under curve (AUC): 0.969]; and distinguished CNS+ carcinomas from CNS- carcinomas and non-cancer neurological diseases (AUC: 0.918). We report here, for the first time, that CSF PGRN levels are higher in patients with CNS+ lymphoma and carcinomas compared to corresponding CNS- diseases. This would imply that measuring CSF PGRN levels could be used to monitor CNS+ lymphoma and metastasis.

Peripheral nerve atrophy together with higher cerebrospinal fluid progranulin indicate axonal damage in amyotrophic lateral sclerosis.

We aimed to investigate whether sonographic peripheral cross-sectional nerve area (CSA) and progranulin (PGRN), a neuritic growth factor, are related to each other and whether they interact to predict clinical and paraclinical measures in amyotrophic lateral sclerosis (ALS). We included 55 ALS patients who had forearm median and ulnar nerve CSA, cerebrospinal fluid (CSF) PGRN, and serum PGRN measures available. CSF PGRN was normalized against the CSF / serum albumin ratio (Qalb ). Using age, sex, height, and weight adjusted general linear models, we examined CSA × CSF PGRN interaction effects on various measures. There was a medium-effect size inverse relationship between CSA and CSF PGRN, but not between CSA and serum PGRN. Lower CSA values together with higher CSF PGRN levels were linked to smaller motor amplitudes. In ALS, the constellation of peripheral nerve atrophy together with higher CSF PGRN levels indicates pronounced axonal damage. Muscle Nerve 57: 273-278, 2018.

Increased cerebrospinal fluid progranulin correlates with interleukin-6 in the acute phase of neuromyelitis optica spectrum disorder

We examined progranulin (PGRN) levels in cerebrospinal fluid (CSF) samples during the acute phase in 15 patients with neuromyelitis optica spectrum disorders (NMOSD) and compared the results with those from 17 patients with multiple sclerosis (MS), 30 patients with other inflammatory neurological diseases (OIND), and 20 non-inflammatory controls (NIC). CSF PGRN levels of NMOSD patients were significantly higher than those of MS patients and NICs. These levels correlated with CSF interleukin-6 levels, CSF cell counts, CSF protein levels, improvements in the Expanded Disability Status Scale score, and affected total spinal cord lesion length in the NMOSD patients.

Cerebrospinal Fluid Progranulin, but Not Serum Progranulin, Is Reduced in GRN-Negative Frontotemporal Dementia

Background and Objective: Reduced progranulin levels are a hallmark of frontotemporal dementia (FTD) caused by loss-of-function (LoF) mutations in the progranulin gene (GRN). However, alterations of central nervous progranulin expression also occur in neurodegenerative disorders unrelated to GRN mutations, such as Alzheimer's disease. We hypothesised that central nervous progranulin levels are also reduced in GRN-negative FTD. Methods: Progranulin levels were determined in both cerebrospinal fluid (CSF) and serum in 75 subjects (37 FTD patients and 38 controls). All FTD patients were assessed by whole-exome sequencing for GRN mutations, yielding a target cohort of 34 patients without pathogenic mutations in GRN (GRN-negative cohort) and 3 GRN mutation carriers (2 LoF variants and 1 novel missense variant). Results: Not only the GRN mutation carriers but also the GRN-negative patients showed decreased CSF levels of progranulin (serum levels in GRN-negative patients were normal). The decreased CSF progranulin levels were unrelated to patients' increased CSF levels of total tau, possibly indicating different destructive neuronal processes within FTD neurodegeneration. The patient with the novel GRN missense variant (c.1117C>T, p.P373S) showed substantially decreased CSF levels of progranulin, comparable to the 2 patients with GRN LoF mutations, suggesting a pathogenic effect of this missense variant. Conclusions: Our results indicate that central nervous progranulin reduction is not restricted to the relatively rare cases of FTD caused by GRN LoF mutations, but also contributes to the more common GRN-negative forms of FTD. Central nervous progranulin reduction might reflect a partially distinct pathogenic mechanism underlying FTD neurodegeneration and is not directly linked to tau alterations.

Soluble sortilin is present in excess and positively correlates with progranulin in CSF of aging individuals

Mutations in progranulin are a major cause of frontotemporal lobe degeneration (FTLD). Hence, plasma progranulin is an attractive biomarker in FTLD but poorly reflects levels in cerebrospinal fluid (CSF), suggesting tissue-specific regulation of progranulin levels. Sortilin was recently identified as a progranulin scavenger receptor that destines it for lysosomal degradation. Proteolysis or alternative splicing generates soluble sortilin variants that retain progranulin binding and potentially functions as a decoy receptor. In the present study, we analyzed soluble sortilin and progranulin in plasma and CSF in 341 aging individuals. We found that soluble sortilin exists in CSF in ten-fold molar excess compared to progranulin and observed a highly significant positive correlation between soluble sortilin and progranulin levels in CSF but not in plasma. However, carriers of the minor allele of SNP rs646776 in SORT1 encoding sortilin displayed significantly increased soluble sortilin and reduced progranulin specifically in plasma but not in CSF. Taken together, our findings suggest that soluble sortilin may affect progranulin levels in both a tissue-specific and genotype-dependent manner.

CSF EXPLORATORY BIOMARKER STUDY FOR (DIFFERENTIAL) DIAGNOSIS OF FRONTOTEMPORAL LOBAR DEGENERATION

There is a need for biomarkers allowing early and differential diagnosis between frontotemporal lobar degeneration (FTLD) and other dementias. Notable candidates include routine Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarkers (pTau181P, hTau, Aβ1-42), non-phosphorylated tau fraction (pTau rel), neurofilament light chain (NF-light), phosphorylated neurofilament heavy chain (pNF-H), progranulin and cathepsin D. Using a cohort of definite FTLD patients, we aimed to explore the performance of these CSF biomarkers. Definite FTLD patients (n=45), clinically diagnosed AD patients (n=45), definite Creutzfeldt-Jakob disease (CJD) patients (n=20) and cognitively healthy controls (n=20) were included in this study. FTLD-TDP (n=28, including 10 GRN and 17 C9orf72 mutation carriers), FTLD-tau (n=10) and FTLD-other (n=7) subgroups were defined by genetic carrier status and/or postmortem neuropathological confirmation. CSF biomarker levels were quantified using commercially available ELISA kits for pTau181P, hTau and Aβ1-42 (INNOTEST ELISAs, Fujirebio Europe, Belgium); hTAU total and pTAU rel (AJ Roboscreen, IBL International GmbH, Germany); NF-light (UmanDiagnostics, IBL International GmbH, Germany); pNF-H (EnCor Biotechnology Inc., USA); progranulin (Adipogen Inc., Korea); cathepsin D (Calbiochem, Merck KGaA, Germany). CSF progranulin levels were significantly lower in FTLD-TDP patients as compared to the FTLD-tau subgroup, due to low levels in GRN mutation carriers. To differentiate between FTLD and AD, pTau181P was the best single marker (AUC=0.922). For further differentiation between FTLD and AD patients, a decision tree was constructed, which showed an added value for NF-light and total tau, correctly classifying 90.8% of the patients (Figure 1). Differentiation between FTLD and controls still proves difficult, with NF-light being the best single marker (AUC=0.700). A decision tree showed that besides NF-light, Aβ1-42 could aid as well, correctly classifying 80.6% of the subjects. The easiest differentiation was that between FTLD and CJD with pTau rel as the best single marker (AUC=0.999). pNF-H and cathepsin D did not contribute to (differential) diagnosis of FTLD. Using single markers, pTau181P and hTau together with NF-light can correctly classify up to 90.8% of FTLD and AD dementia patients. Differentiation between FTLD and controls remains suboptimal, even when combining NF-light and Aβ1-42 (correct classification of 80.6%). Decision tree for differential diagnosis between FTLD and AD patients, with an overall correct classification of 90.8%. pTau181P, phosphorylated tau; hTau, total tau; NF-light, neurofilament light chain.

Progranulin Protein Levels in Cerebrospinal Fluid in Primary Neurodegenerative Dementias.

Progranulin is implicated in frontotemporal dementia (FTD), but its role in other neurodegenerative disorders is unknown. To investigate the levels of progranulin (PGRN) in cerebrospinal fluid (CSF) in different neurodegenerative dementias and their correlation with levels in plasma in cognitively normal subjects. We measured PGRN in CSF in 229 patients with amnestic mild cognitive impairment, Alzheimer's disease dementia, sporadic FTD, dementia with Lewy bodies, corticobasal syndrome, or progressive supranuclear palsy. We also measured PGRN in CSF and plasma in 74 cognitively normal individuals. We examined the correlation between PGRN levels in CSF and diagnosis, cortical thickness, genetic factors and other CSF biomarkers. We also investigated the correlation between plasma and CSF levels of PGRN in cognitively normal individuals. CSF levels did not differ across diagnoses or correlate with cortical thickness. Polymorphism rs5848 in GRN influenced CSF PGRN levels, but APOEɛ4 allele did not. Amyloid-β42, t-tau, p-tau, and YKL-40 levels correlated weakly with PGRN in CSF. We found a weak correlation (r = 0.362) between plasma and CSF PGRN levels in cognitively normal individuals. Our findings do not support a diagnostic value of CSF PGRN in neurodegenerative diseases. Our data confirm that levels of PGRN in plasma do not reflect accurately levels in CSF in cognitively normal controls. These data should be considered in clinical trials aiming to increase PGRN.

Progranulin as a candidate biomarker for therapeutic trial in patients with ALS and FTLD.

The loss-of-function mechanism in progranulin (PGRN) mutation carriers makes PGRN an interesting target for upregulation as a therapeutic approach in neurodegenerative diseases like frontotemporal lobar degeneration. This gives rise to several questions: (1) how stable are PGRN levels in blood and cerebrospinal fluid (CSF) in follow-up? (2) Is it necessary to measure PGRN levels in CSF to monitor a therapeutic effect? Therefore, concentrations of PGRN were measured in paired CSF and serum samples of 22 patients with behavioural variant frontotemporal dementia, including one GRN mutation carrier (c.349+1G>C), 16 patients with amyotrophic lateral sclerosis and 17 non-neurodegenerative patients, which included 22 follow-up levels. PGRN levels of 14 patients with isolated dysfunction of the blood-CSF barrier were measured and PGRN was correlated with albumin quotients as a marker for blood-CSF barrier function. The intrathecal fraction of PGRN was calculated on the basis of CSF-to-serum ratios and hydrodynamic properties. Follow-up measurements of CSF and serum PGRN levels did not show any significant change in diagnostic groups. Mean PGRN levels are 35 times higher in blood than in CSF. However, the CSF-to-serum PGRN ratio does not correlate with the albumin quotient even in patients with severe impairment of the blood-CSF barrier. The calculated intrathecal fraction of CSF PGRN levels ranged between 80 and 90%. Assuming that CSF PGRN is either brain-derived or transported from the vascular compartment via receptor mediated mechanisms, we propose that monitoring CNS specific effects of PGRN modulating drugs should be done in CSF.

Quantification and regulation of the adipokines resistin and progranulin in human cerebrospinal fluid.

Adipokines bearing the potential to cross the blood-brain barrier (BBB) are promising candidates for the endocrine regulation of central nervous processes and of a postulated fat-brain axis. Resistin and progranulin concentrations in paired serum and cerebrospinal fluid (CSF) samples of patients undergoing neurological evaluation and spinal puncture were investigated. Samples of n = 270 consecutive patients with various neurological diseases were collected without prior selection. Adipokine serum and CSF concentrations were measured by enzyme-linked immunosorbent assay and serum and CSF routine parameters by standard procedures. Anthropometric data, medication and patient history were available. Serum levels of resistin and progranulin were positively correlated among each other, with respective CSF levels, low-density lipoprotein cholesterol levels and markers of systemic inflammation. CSF resistin concentrations were generally low. Progranulin CSF concentrations and CSF/serum progranulin ratio were significantly higher in patients with infectious diseases, with disturbed BBB function and with elevated CSF cell count and presence of oligoclonal bands. Both adipokines are able to cross the BBB depending on a differing patency that increases with increasing grade of barrier dysfunction. Whereas resistin represents a systemic marker of inflammation, CSF progranulin levels strongly depend on the underlying disease and dysfunction of blood-CSF barrier. Resistin and progranulin represent novel and putative regulators of the fat-brain axis by their ability to cross the BBB under physiological and pathophysiological conditions. The presented data provide insight into the characteristics of BBB function regarding progranulin and resistin and the basis for future establishment of normal values for CSF concentrations and CSF/serum ratios.

Progranulin levels in status epilepticus as a marker of neuronal recovery and neuroprotection.

Recently, a mouse model showed that progranulin, a mediator in neuroinflammation and a neuronal growth factor, was elevated in the hippocampus after status epilepticus (SE). This elevated level might mirror compensating neuronal mechanisms after SE. Studies concerning neuronal recovery and neuroprotective mechanisms after SE in humans are scarce, so we tested for progranulinin the cerebrospinal fluid (CSF) after various types of SE. We performed a retrospective analysis of progranulin levels in CSF in patients (n = 24) who underwent lumbar puncture as part of diagnostic workup after having SE and in patients after having one single tonic-clonic seizure who comprised the control group (n = 8). In our group with SE, progranulin levels in CSF were not significantly elevated compared to our control group. Furthermore, there was no correlation between progranulin levels and the time interval between lumbar puncture and SE. Additionally, in cases of higher CSF progranulin levels, we found no impact on the clinical outcome after SE. Although our cohort is heterogeneous and not fully sufficient, we conclude that progranulin in CSF is not elevated after SE in our cohort. Therefore, our results do not suggest a change in cerebral progranulin metabolism as a possible neuroregenerative or neuroprotective mechanism in humans after SE in acute and subacute phases. A larger cohort study is needed to further strengthen this result. This article is part of a Special Issue entitled "Status Epilepticus".

Cerebrospinal fluid progranulin levels in patients with different multiple sclerosis subtypes

Progranulin has recently attracted attention due to the discovery of mutations in its encoding gene (GRN) in several cases of frontotemporal lobar degeneration, but also for a possible role in inflammatory processes. In adult central nervous system, GRN mRNA is expressed in forebrain, olfactory bulbs and spinal cord. Progranulin cerebrospinal fluid (CSF) levels were evaluated in 55 patients with multiple sclerosis (MS) as well as in 35 subjects with non-inflammatory neurological diseases (NIND), 7 individuals with other inflammatory neurological disease (OIND) and 8 controls (CON), matched for ethnic background, gender and age. No statistically significant differences were found in patients compared with either NIND, OIND or CON (P>0.05), even stratifying according to disease subtype or gender. A positive correlation between progranulin CSF levels and age was observed in patients (rho=0.29, P=0.03). According to these data, progranulin does not likely play a major role in the pathogenesis of MS.