Cerebrospinal fluid neopterin as a biomarker of treatment response to Janus kinase inhibition in Aicardi-Goutières syndrome.

Janus kinase (JAK) 1 inhibition represents a precision medicine approach in the treatment of Aicardi-Goutières syndrome (AGS), through targeting of type I interferon-mediated cell signalling. Blood interferon mRNAseq has been proposed as a biomarker of disease with utility in therapeutic monitoring. Objective cerebrospinal fluid (CSF) biomarkers tracking treatment efficacy are currently lacking. Here, we report a retrospective case series of 13 patients (median age 6y, range 2y 6mo-17y; five females, eight males) with AGS demonstrating significantly elevated CSF neopterin levels at first sampling (median 200nmol/L, range 45-2024nmol/L), compared to 13 age-matched controls with non-inflammatory neurological conditions (median 23nmol/L, range 5-34nmol/L, p<0.001). Five patients with AGS treated with JAK inhibitors demonstrated a median 81.5% reduction of CSF neopterin (range -36% to -88% change from baseline), compared to eight untreated patients with AGS demonstrating a median 7% reduction in CSF neopterin (range -63% to +117% change) (p=0.047). Our data indicate a biological effect of JAK inhibitors, and the potential role of CSF neopterin as a biomarker of treatment response.

Cerebrospinal fluid metabolites in tryptophan-kynurenine and nitric oxide pathways: biomarkers for acute neuroinflammation.

AIM: To explore the cerebrospinal fluid (CSF) metabolite features in acute neuroinflammatory diseases and identify potential biomarkers to diagnose and monitor neuroinflammation. METHOD: A cohort of 14 patients (five females, nine males; mean [median] age 7y 9mo [9y], range 6mo-13y) with acute encephalitis (acute disseminated encephalomyelitis n=6, unknown suspected viral encephalitis n=3, enteroviral encephalitis n=2, seronegative autoimmune encephalitis n=2, herpes simplex encephalitis n=1) and age-matched non-inflammatory neurological disease controls (n=14) were investigated using an untargeted metabolomics approach. CSF metabolites were analyzed with liquid chromatography coupled to high resolution mass spectrometry, followed by subsequent multivariate and univariate statistical methods. RESULTS: A total of 35 metabolites could be discriminated statistically between the groups using supervised orthogonal partial least squares discriminant analysis and analysis of variance. The tryptophan-kynurenine pathway contributed nine key metabolites. There was a statistical increase of kynurenine, quinolinic acid, and anthranilic acid in patients with encephalitis, whereas tryptophan, 3-hydroxyanthrnailic acid, and kynurenic acid were decreased. The nitric oxide pathway contributed four metabolites, with elevated asymmetric dimethylarginine and argininosuccinic acid, and decreased arginine and citrulline in patients with encephalitis. An increase in the CSF kynurenine/tryptophan ratio (p<0.001), anthranilic acid/3-hydroxyanthranilic acid ratio (p<0.001), asymmetric dimethylarginine/arginine ratio (p<0.001), and neopterin (p<0.001) strongly predicted neuroinflammation. INTERPRETATION: The combination of alterations in the tryptophan-kynurenine pathway, nitric oxide pathway, and neopterin represent a useful potential panel for neuroinflammation and holds potential for clinical translation practice. WHAT THIS PAPER ADDS: The kynurenine/tryptophan and anthranilic acid/3-hydroxyanthranilic acid ratios hold great potential as biomarkers of neuroinflammation. Elevation of the asymmetric dimethylarginine/arginine ratio in acute brain inflammation shows dysregulation of the nitric oxide pathway.

Evaluation of target attainment of oral posaconazole suspension in immunocompromised children.

BACKGROUND: Posaconazole is a broad-spectrum antifungal that is not licensed for use in children <13 years of age. Despite this and by necessity, it is used extensively in paediatric hospitals for prophylaxis of invasive fungal disease. OBJECTIVES: To determine whether initial prophylactic dosing recommendations attain a posaconazole plasma concentration of ≥700 ng/mL in immunocompromised children <13 years of age. PATIENTS AND METHODS: We performed a retrospective study of immunocompromised children <13 years of age receiving posaconazole suspension prophylaxis at a starting dose of 5 mg/kg every 8 h for ≥7 days and who had a posaconazole concentration measured after ≥7 days. Posaconazole plasma concentrations and rate of breakthrough infection were recorded. RESULTS: A total of 70 patients were included with a median age of 5 years (range 3 months to 12 years). The mean posaconazole plasma concentration was 783.4 ng/mL (IQR 428.3-980 ng/mL) and the percentage of patients with a posaconazole plasma concentration ≥700ng/mL was 47.9%. Patients who were on a proton pump inhibitor, a histamine H2 antagonist or metoclopramide, had mucositis or were enterally fed had a lower posaconazole plasma concentration compared with patients without these co-administered drugs/mucositis/enteral feeding (542.3 versus 1069.8 ng/mL; P<0.001). The breakthrough invasive fungal infection rate was 4.3% (3/70). CONCLUSIONS: The studied 5 mg/kg posaconazole suspension every 8 h resulted in target concentrations in only 47.9% of patients and further studies looking at newer posaconazole formulations are needed.

Etiology is the key determinant of neuroinflammation in epilepsy: Elevation of cerebrospinal fluid cytokines and chemokines in febrile infection-related epilepsy syndrome and febrile status epilepticus.

OBJECTIVE: To investigate intrathecal inflammation using cerebrospinal fluid (CSF) cytokines and chemokines in a subgroup of pediatric epilepsy patients with frequent daily seizures. METHODS: We measured 32 cytokines/chemokines using multiplex immunoassay in CSF collected from pediatric patients with febrile infection-related epilepsy syndrome (FIRES)/FIRES-related disorders (FRD; n = 6), febrile status epilepticus (FSE; n = 8), afebrile status epilepticus (ASE; n = 8), and chronic epilepsy with frequent daily seizures (n = 21) and compared the results with noninflammatory neurological disorders (NIND; n = 20) and encephalitis (n = 43). We also performed longitudinal CSF cytokine/chemokine studies in three cases with FIRES/FRD. RESULTS: The median age of onset of seizures was 2.4 years (range = 0.08-12.5). Median CSF timing from the onset of seizures was longer in chronic epilepsy (540 days), whereas FIRES, FSE, and ASE had CSF tested within 1-2 days of onset of seizures (P < .001). The elevation of cytokines/chemokines was higher in FIRES followed by FSE, when compared to chronic epilepsy and NIND controls. Th1-associated cytokines/chemokines (TNF-α, CXCL9, CXCL10, CXCL11), IL-6, CCL2, CCL19, and CXCL1 (P < .05) were elevated in FIRES, in contrast to the elevation of a broader network of cytokines/chemokines in encephalitis. The cytokines/chemokines (CXCL9, CXCL10, CXCL11, and CCL19) were elevated in FSE when compared to ASE despite the similar median seizure duration and timing of CSF testing in relation to seizures. Chronic epilepsy generally lacked significant elevation of cytokines/chemokines despite frequent daily seizures. The median concentrations of the cytokines/chemokines rapidly declined on serial testing during the course of illness in all three FIRES/FRD cases. SIGNIFICANCE: We identify significant differences in CSF cytokine/chemokine profile between FIRES/FRD and encephalitis. The prominent elevation of CSF cytokines and chemokines in FIRES/FRD and to a lesser extent FSE highlights that the cytokine/chemokine elevation is significantly associated with the etiology of the underlying process rather than purely reactive. However, it is unclear whether the immune activation contributes to the disease process.

Development and validation of a simple, rapid and sensitive LC-MS/MS method for the measurement of urinary neurotransmitters and their metabolites.

Neurotransmitters play crucial roles in physiological functions and their imbalances have demonstrated association in the pathology of several diseases. The measurement of neurotransmitters possesses a great potential as a significant clinical tool. This study presents the development and validation of an LC-MS/MS method for simultaneous quantification of multi-class neurotransmitters associated with dopamine, tryptophan and glutamate-γ-aminobutyric acid pathways. A total of ten neurotransmitters and their metabolites (dopamine, epinephrine, metanephrine, tryptophan, serotonin, kynurenic acid, kynurenine, anthranilic acid, GABA, glutamic acid) were determined based on a simple and rapid 'dilute and shoot' method using minimal urine volume. The chromatographic separation was achieved using a Poroshell 120 Bonus-RP LC Column in combination with a gradient elution within an 8.5-min time frame. The method exhibited good sensitivity as the limits of quantification ranged between 0.025 and 0.075 µg/mL with acceptable matrix effects (< ± 14.5%), no carryover and good linearity (r 2 > 0.98). The accuracy and precision for all analytes were within tolerances, at < ± 9.9% mean relative error (MRE) and < 8.6% relative standard deviation (RSD), respectively. The method was successfully applied in measuring the neurotransmitter concentrations in urine of healthy donors. Furthermore, the undertaken stability experiments indicated that acidified urine specimens allowed the analytes to be stable for prolonged durations in comparison to those untreated. The study also reveals the performance of the method is unaffected by the absence of expensive deuterated reference standards under the experimental conditions employed which further simplifies the analytical procedures and provides a significant cost saving for running the assay. Graphical abstract The quantification of multi-class neurotransitters associated with the dopamine, tryptophan and GABA-glutamate pathways using a simple 'dilute and shoot' LC-MS/MS method.

Cerebrospinal fluid cyto-/chemokine profile during acute herpes simplex virus induced anti-N-methyl-d-aspartate receptor encephalitis and in chronic neurological sequelae.

AIM: To examine the cytokine/chemokine profile of cerebrospinal fluid (CSF) during acute herpes simplex virus-induced N-methyl-d-aspartate receptor (NMDAR) autoimmunity and in chronic/relapsing post-herpes simplex virus encephalitis (HSE) neurological syndromes. METHOD: We measured longitudinal serial CSF cyto-/chemokines (n=34) and a glial marker (calcium-binding astroglial protein, S100B) in one patient during acute HSE and subsequent anti-NMDAR encephalitis, and compared the results with those from two patients with anti-NMDAR encephalitis without preceding HSE. We also compared cyto-/chemokines in cross-sectional CSF samples from three children with previous HSE who had ongoing chronic or relapsing neurological symptoms (2yr 9 mo-16y after HSE) with those in a group of children having non-inflammatory neurological conditions (n=20). RESULTS: Acute HSE showed elevation of a broad range of all T-helper-subset-related cyto-/chemokines and S100B whereas the post-HSE anti-NMDAR encephalitis phase showed persistent elevation of two of five T-helper-1 (chemokine [C-X-C motif] ligand 9 [CXCL9], CXCL10), three of five predominantly B-cell (CXCL13, CCL19, a proliferation-inducing ligand [APRIL])-mediated cyto-/chemokines, and interferon-α. The post-HSE anti-NMDAR encephalitis inflammatory response was more pronounced than anti-NMDAR encephalitis. All three chronic post-HSE cases showed persistent elevation of CXCL9, CXCL10, and interferon-α, and there was histopathological evidence of chronic lymphocytic inflammation in one biopsied case 7 years after HSE. Two of three chronic cases showed a modest response to immune therapy. INTERPRETATION: HSE-induced anti-NMDAR encephalitis is a complex and pronounced inflammatory syndrome. There is persistent CSF upregulation of cyto-/chemokines in chronic or relapsing post-HSE neurological symptoms, which may be modifiable with immune therapy. The elevated cyto-/chemokines may be targets of monoclonal therapies.

Impact of assay design on test performance: lessons learned from 25-hydroxyvitamin D.

BACKGROUND: Current automated immunoassays vary significantly in many aspects of their design. This study sought to establish if the theoretical advantages and disadvantages associated with different design formats of automated 25-hydroxyvitamin D (25-OHD) assays are translated into variations in assay performance in practice. METHODS: 25-OHD was measured in 1236 samples using automated assays from Abbott, DiaSorin, Roche and Siemens. A subset of 362 samples had up to three liquid chromatography-tandem mass spectrometry 25-OHD analyses performed. 25-OHD2 recovery, dilution recovery, human anti-animal antibody (HAAA) interference, 3-epi-25-OHD3 cross-reactivity and precision of the automated assays were evaluated. RESULTS: The assay that combined release of 25-OHD with analyte capture in a single step showed the most accurate 25-OHD2 recovery and the best dilution recovery. The use of vitamin D binding protein (DBP) as the capture moiety was associated with 25-OHD2 under-recovery, a trend consistent with 3-epi-25-OHD3 cross-reactivity and immunity to HAAA interference. Assays using animal-derived antibodies did not show 3-epi-25-OHD3 cross-reactivity but were variably susceptible to HAAA interference. Not combining 25-OHD release and capture in one step and use of biotin-streptavidin interaction for solid phase separation were features of the assays with inferior accuracy for diluted samples. The assays that used a backfill assay format showed the best precision at high concentrations but this design did not guarantee precision at low 25-OHD concentrations. CONCLUSIONS: Variations in design among automated 25-OHD assays influence their performance characteristics. Consideration of the details of assay design is therefore important when selecting and validating new assays.

Long-Term Safety and Efficacy of Transcatheter Microwave and Radiofrequency Denervation in a Chronic Ovine Model.

BACKGROUND: Transcatheter renal denervation (RDN) has had inconsistent efficacy and concerns for durability of denervation. We aimed to investigate long-term safety and efficacy of transcatheter microwave RDN in vivo in normotensive sheep in comparison to conventional radiofrequency ablation. METHODS AND RESULTS: Sheep underwent bilateral RDN, receiving 1 to 2 microwave ablations (maximum power of 80-120 W for 240 s-480 s) and 12 to 16 radiofrequency ablations (180 s-240 s) in the main renal artery in a paired fashion, alternating the side of treatment, euthanized at 2 weeks (acute N=15) or 5.5 months (chronic N=15), and compared with undenervated controls (N=4). Microwave RDN produced substantial circumferential perivascular injury compared with radiofrequency at both 2 weeks [area 239.8 (interquartile range [IQR] 152.0-343.4) mm2 versus 50.1 (IQR, 32.0-74.6) mm2, P <0.001; depth 16.4 (IQR, 13.9-18.9) mm versus 7.5 (IQR, 6.0-8.9) mm P <0.001] and 5.5 months [area 20.0 (IQR, 3.4-31.8) mm2 versus 5.0 (IQR, 1.4-7.3) mm2, P=0.025; depth 5.9 (IQR, 1.9-8.8) mm versus 3.1 (IQR, 1.2-4.1) mm, P=0.005] using mixed models. Renal denervation resulted in significant long-term reductions in viability of renal sympathetic nerves [58.9% reduction with microwave (P=0.01) and 45% reduction with radiofrequency (P=0.017)] and median cortical norepinephrine levels [71% reduction with microwave (P <0.001) and 72.9% reduction with radiofrequency (P <0.001)] at 5.5 months compared with undenervated controls. CONCLUSIONS: Transcatheter microwave RDN produces deep circumferential perivascular ablations without significant arterial injury to provide effective and durable RDN at 5.5 months compared with radiofrequency RDN.

Developmental delay and non-phenylketonuria (PKU) hyperphenylalaninemia in DNAJC12 deficiency: Case and approach.

BACKGROUND: Hyperphenylalaninemia is a biomarker for several monogenic neurotransmitter disorders where the body cannot metabolise phenylalanine to tyrosine. Biallelic pathogenic variants in DNAJC12, co-chaperone of phenylalanine, tyrosine, and tryptophan hydroxylases, leads to hyperphenylalaninemia and biogenic amines deficiency. METHODS AND RESULTS: A male firstborn to non-consanguineous Sudanese parents had hyperphenylalaninemia 247 µmol/L [reference interval (RI) < 200 µmol/L] at newborn screening. Dried blood spot dihydropteridine reductase (DHPR) assay and urine pterins were normal. He had severe developmental delay and autism spectrum disorder without a notable movement disorder. A low phenylalanine diet was introduced at two years without any clinical improvements. Cerebrospinal fluid (CSF) neurotransmitters at five years demonstrated low homovanillic acid (HVA) 0.259 µmol/L (reference interval (RI) 0.345-0.716) and 5-hydroxyindoleaetic acid (5HIAA) levels 0.024 µmol/L (reference interval (RI) 0.100-0.245). Targeted neurotransmitter gene panel analysis identified a homozygous c.78 + 1del variant in DNAJC12. At six years, he was commenced on 5-hydroxytryptophan 20 mg daily, and his protein-restricted diet was liberalised, with continued good control of phenylalanine levels. Sapropterin dihydrochloride 7.2 mg/kg/day was added the following year with no observable clinical benefits. He remains globally delayed with severe autistic traits. CONCLUSIONS: Urine, CSF neurotransmitter studies, and genetic testing will differentiate between phenylketonuria, tetrahydrobiopterin or DNAJC12 deficiency, with the latter characterised by a clinical spectrum ranging from mild autistic features or hyperactivity to severe intellectual disability, dystonia, and movement disorder, normal DHPR, reduced CSF HIAA and HVA. DNAJC12 deficiency should be considered early in the differential workup of hyperphenylalaninemia identified from newborn screening, with its genotyping performed once deficiencies of phenylalanine hydroxylase (PAH) and tetrahydrobiopterin (BH4) have been biochemically or genetically excluded.

CSF neopterin and quinolinic acid are biomarkers of neuroinflammation and neurotoxicity in FIRES and other infection-triggered encephalopathy syndromes.

OBJECTIVE: Infection-triggered encephalopathy syndromes (ITES) are potentially devastating neuroinflammatory conditions. Although some ITES syndromes have recognisable MRI neuroimaging phenotypes, there are otherwise few biomarkers of disease. Early detection to enable immune modulatory treatments could improve outcomes. METHODS: We measured CSF neopterin, quinolinic acid, kynurenine and kynurenine/tryptophan ratio using a liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) system. The CSF of 18 children with ITES were compared with acute encephalitis (n = 20), and three control groups, namely epilepsy (n = 20), status epilepticus (n = 18) and neurogenetic controls (n = 20). RESULTS: The main ITES phenotypes in 18 patients were acute encephalopathy with biphasic seizures and late restricted diffusion (AESD, n = 4), febrile infection-related epilepsy syndrome (FIRES n = 4) and other ITES phenotypes. Influenza A was the most common infectious trigger (n = 5), and 50% of patients had a preceding notable neurodevelopmental or family history. CSF neopterin, quinolinic acid and kynurenine were elevated in ITES group compared to the three control groups (all p < 0.0002). The ROC (area under curve) for CSF neopterin (99.3%, CI 98.1-100) was significantly better than CSF pleocytosis (87.3% CI 76.4-98.2) (p = 0.028). Elevated CSF neopterin could discriminate ITES from other causes of seizures, status epilepticus and febrile status epilepticus (all p < 0.0002). The elevated CSF metabolites normalised during longitudinal testing in two patients with FIRES. INTERPRETATION: CSF neopterin and quinolinic acid are neuroinflammatory and excitotoxic metabolites. This CSF metabolomic inflammatory panel can discriminate ITES from other causes of new onset seizures or status epilepticus, and rapid results (4 h) may facilitate early immune modulatory therapy.

CSF neopterin, quinolinic acid and kynurenine/tryptophan ratio are biomarkers of active neuroinflammation.

BACKGROUND: Defining the presence of acute and chronic brain inflammation remains a challenge to clinicians due to the heterogeneity of clinical presentations and aetiologies. However, defining the presence of neuroinflammation, and monitoring the effects of therapy is important given its reversible and potentially damaging nature. We investigated the utility of CSF metabolites in the diagnosis of primary neuroinflammatory disorders such as encephalitis and explored the potential pathogenic role of inflammation in epilepsy. METHODS: Cerebrospinal fluid (CSF) collected from 341 paediatric patients (169 males, median age 5.8 years, range 0.1-17.1) were examined. The patients were separated into a primary inflammatory disorder group (n = 90) and epilepsy group (n = 80), who were compared with three control groups including neurogenetic and structural (n = 76), neurodevelopmental disorders, psychiatric and functional neurological disorders (n = 63), and headache (n = 32). FINDINGS: There were statistically significant increases of CSF neopterin, kynurenine, quinolinic acid and kynurenine/tryptophan ratio (KYN/TRP) in the inflammation group compared to all control groups (all p < 0.0003). As biomarkers, at thresholds with 95% specificity, CSF neopterin had the best sensitivity for defining neuroinflammation (82%, CI 73-89), then quinolinic acid (57%, CI 47-67), KYN/TRP ratio (47%, CI 36-56) and kynurenine (37%, CI 28-48). CSF pleocytosis had sensitivity of 53%, CI 42-64). The area under the receiver operating characteristic curve (ROC AUC) of CSF neopterin (94.4% CI 91.0-97.7%) was superior to that of CSF pleocytosis (84.9% CI 79.5-90.4%) (p = 0.005). CSF kynurenic acid/kynurenine ratio (KYNA/KYN) was statistically decreased in the epilepsy group compared to all control groups (all p ≤ 0.0003), which was evident in most epilepsy subgroups. INTERPRETATION: Here we show that CSF neopterin, kynurenine, quinolinic acid and KYN/TRP are useful diagnostic and monitoring biomarkers of neuroinflammation. These findings provide biological insights into the role of inflammatory metabolism in neurological disorders and provide diagnostic and therapeutic opportunities for improved management of neurological diseases. FUNDING: Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, University of Sydney, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead. Prof Guillemin is funded by NHMRC Investigator grant APP 1176660 and Macquarie University.

Development of a translational inflammation panel for the quantification of cerebrospinal fluid Pterin, Tryptophan-Kynurenine and Nitric oxide pathway metabolites.

BACKGROUND: Neuroinflammatory diseases such as encephalitis, meningitis, multiple sclerosis and other neurological diseases with inflammatory components, have demonstrated a need for diagnostic biomarkers to define treatable and reversible neuroinflammation. The development and clinical validation of a targeted translational inflammation panel using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) could provide early diagnosis, rapid treatment and insights into neuroinflammatory mechanisms. METHODS: An inflammation panel of 13 metabolites (neopterin, tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, xanthurenic acid, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid, picolinic acid, arginine, citrulline and methylhistamine) was measured based on a simple precipitation and filtration method using minimal CSF volume. The chromatographic separation was achieved using the Acquity UPLC BEH C18 column in combination with a gradient elution within a 12-min time frame. Acute encephalitis (n=10; myelin oligodendrocyte glycoprotein encephalitis n=3, anti-N-methyl-D-aspartate encephalitis n=2, acute disseminated encephalomyelitis n=2, herpes simplex encephalitis n=1, enteroviral encephalitis n=1) and frequency-matched non-inflammatory neurological disease controls (n=10) were examined. FINDINGS: The method exhibited good sensitivity as the limits of quantification ranged between 0.75 and 3.00 ng mL-1, good linearity (r2 > 0.99), acceptable matrix effects (<± 19.4%) and high recoveries (89.8-109.1 %). There were no interferences observed from common endogenous CSF metabolites, no carryover and concordance with well-established clinical methods. The accuracy and precision for all analytes were within tolerances, at <± 15 mean relative error and < 15 % coefficient of variation respectively. All analytes in matrix-matched pooled human CSF calibrators and human CSF extracts were stable for 24 h after extraction and two freeze-thaw cycles. INTERPRETATION: The method was successfully applied to a pilot study investigating acute brain inflammation case-control groups. Statistical discrimination between encephalitis (n=10) and control groups (n=10) was achieved using orthogonal partial least squares discriminant analysis and heatmap cluster analysis. Statistical analysis of the measured metabolites identified significant alterations of seven metabolites in the tryptophan-kynurenine pathway (tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid), arginine and neopterin in presence of acute neuroinflammation. Furthermore, elevated ratios of CSF kynurenine/tryptophan ratio, quinolinic acid/kynurenic acid and anthranilic acid/3-hydroxyanthranilic acid provided strong discriminative power for neuroinflammatory conditions. Studies of large groups of neurological diseases are required to explore the sensitivity and specificity of the inflammation panel. FUNDING: Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead.

Decreased cerebrospinal fluid kynurenic acid in epileptic spasms: A biomarker of response to corticosteroids.

BACKGROUND: Epileptic (previously infantile) spasms is the most common epileptic encephalopathy occurring during infancy and is frequently associated with abnormal neurodevelopmental outcomes. Epileptic spasms have a diverse range of known (genetic, structural) and unknown aetiologies. High dose corticosteroid treatment for 4 weeks often induces remission of spasms, although the mechanism of action of corticosteroid is unclear. Animal models of epileptic spasms have shown decreased brain kynurenic acid, which is increased after treatment with the ketogenic diet. We quantified kynurenine pathway metabolites in the cerebrospinal fluid (CSF) of infants with epileptic spasms and explored clinical correlations. METHODS: A panel of nine metabolites in the kynurenine pathway (tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, xanthurenic acid, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid, and picolinic acid) were measured using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). CSF collected from paediatric patients less than 3 years of age with epileptic spasms (n=34, 19 males, mean age 0.85, median 0.6, range 0.3-3 yrs) were compared with other epilepsy syndromes (n=26, 9 males, mean age 1.44, median 1.45, range 0.3-3 yrs), other non-inflammatory neurological diseases (OND) (n=29, 18 males, mean age 1.47, median 1.6, range 0.1-2.9 yrs) and inflammatory neurological controls (n=12, 4 males, mean age 1.80, median 1.80, range 0.8-2.5 yrs). FINDINGS: There was a statistically significant decrease of CSF kynurenic acid in patients with epileptic spasms compared to OND (p<0.0001). In addition, the kynurenic acid/kynurenine (KYNA/KYN) ratio was lower in the epileptic spasms subgroup compared to OND (p<0.0001). Epileptic spasms patients who were steroid responders or partial steroid responders had lower KYNA/KYN ratio compared to patients who were refractory to steroids (p<0.005, p<0.05 respectively). INTERPRETATION: This study demonstrates decreased CSF kynurenic acid and KYNA/KYN in epileptic spasms, which may also represent a biomarker for steroid responsiveness. Given the anti-inflammatory and neuroprotective properties of kynurenic acid, further therapeutics able to increase kynurenic acid should be explored. FUNDING: Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead. Prof Guillemin is funded by NHMRC Investigator grant APP1176660 and Macquarie University.

Cerebrospinal fluid metabolomics: detection of neuroinflammation in human central nervous system disease.

The high morbidity and mortality of neuroinflammatory diseases drives significant interest in understanding the underlying mechanisms involved in the innate and adaptive immune response of the central nervous system (CNS). Diagnostic biomarkers are important to define treatable neuroinflammation. Metabolomics is a rapidly evolving research area offering novel insights into metabolic pathways, and elucidation of reliable metabolites as biomarkers for diseases. This review focuses on the emerging literature regarding the detection of neuroinflammation using cerebrospinal fluid (CSF) metabolomics in human cohort studies. Studies of classic neuroinflammatory disorders such as encephalitis, CNS infection and multiple sclerosis confirm the utility of CSF metabolomics. Additionally, studies in neurodegeneration and neuropsychiatry support the emerging potential of CSF metabolomics to detect neuroinflammation in common CNS diseases such as Alzheimer's disease and depression. We demonstrate metabolites in the tryptophan-kynurenine pathway, nitric oxide pathway, neopterin and major lipid species show moderately consistent ability to differentiate patients with neuroinflammation from controls. Integration of CSF metabolomics into clinical practice is warranted to improve recognition and treatment of neuroinflammation.

Elevation of cerebrospinal fluid cytokine/chemokines involved in innate, T cell, and granulocyte inflammation in pediatric focal cerebral arteriopathy.

AIM: To determine the role of inflammation in pediatric transient focal cerebral arteriopathy using cerebrospinal fluid cytokine/chemokines as biomarkers. METHODS: We measured 32 cytokine/chemokines in acute cerebrospinal fluid collected from children with stroke due to focal cerebral arteriopathy (n = 5) using multiplex immunoassay and compared with two patients with arterial ischemic stroke due to other causes (non-focal cerebral arteriopathy group, vertebral dissection, n = 1; cryptogenic, n = 1), pediatric encephalitis (n = 43), and non-inflammatory neurological disease controls (n = 20). RESULTS: Median age in the focal cerebral arteriopathy group was 9.3 years (range, 2.8-13 years). In the focal cerebral arteriopathy group (n = 5), four patients had middle cerebral ± distal carotid arteriopathy; one patient had posterior circulation arteriopathy. The median time from symptom onset to cerebrospinal fluid sampling was four days (range, 0.6-7 days). Only IL-6, IL-8, CXCL1, and CXCL10 levels were significantly higher in the acute cerebrospinal fluid of focal cerebral arteriopathy patients compared to non-inflammatory neurological disease controls and non-focal cerebral arteriopathy stroke. In contrast to focal cerebral arteriopathy, a broad array of Th1, Th2, Treg, Th17, B-cell related, and other broad spectrum cytokine/chemokines were elevated in encephalitis. CONCLUSION: The elevated cerebrospinal fluid cytokine/chemokines support innate, T cell, and granulocyte inflammatory mechanisms in children with focal cerebral arteriopathy. This warrants larger cohort studies to discriminate primary inflammatory signals of the arteriopathy from secondary inflammation due to the stroke itself.

Novel Surrogate Markers of CNS Inflammation in CSF in the Diagnosis of Autoimmune Encephalitis.

Background: Autoimmune encephalitis (AE) is an important cause of refractory epilepsy, rapidly progressive cognitive decline, and unexplained movement disorders in adults. Whilst there is identification of an increasing number of associated autoantibodies, patients remain with a high clinical probability of autoimmune encephalitis but no associated characterized autoantibody. These patients represent a diagnostic and treatment dilemma. Objective: To evaluate routine and novel diagnostic tests of cerebrospinal fluid (CSF) in patients with a high probability of AE to attempt to identify better biomarkers of neuroinflammation. Methods: Over 18 months (2016-2018), adult patients with a high clinical probability of AE were recruited for a pilot cross-sectional explorative study. We also included viral polymerase-chain-reaction (PCR) positive CSF samples and CSF from neurology patients with "non-inflammatory" (NI) diagnoses for comparison. CSF was examined with standard investigations for encephalitis and novel markers (CSF light chains, and cytokines). Results and Conclusions: Thirty-two AE patients were recruited over 18 months. Twenty-one viral controls, 10 NI controls, and five other autoimmune neurological disease controls (AOND) were also included in the analysis. Our study found that conventional markers: presence of CSF monocytosis, oligoclonal bands, anti-neuronal immunofluorescence, and magnetic resonance imaging (MRI) changes could be suggestive of AE, but these investigations were neither sensitive nor specific. Promising novel makers of autoimmune encephalitis were the CSF cytokines IL-21 and IP10 which may provide better delineation between viral infections and autoimmune encephalitis than conventional markers, potentially leading to more immediate diagnosis and management of these patients.

Transvascular Pacing of Aorticorenal Ganglia Provides a Testable Procedural Endpoint for Renal Artery Denervation.

OBJECTIVES: This study sought to develop a method to assess renal sympathetic nerve function through localization and pacing of aorticorenal ganglia (ARG). BACKGROUND: Transcatheter renal denervation procedures often fail to produce complete renal denervation because of the lack of a physiological procedural endpoint. METHODS: High-frequency pacing was performed in the inferior vena cava and aorta in sheep (n = 19) to identify ARG pace-capture sites. Group A (n = 5) underwent injection at the ARG pace-capture site for histological verification, group B (n = 6) underwent unilateral irrigated radiofrequency ablation of ARG pace-capture sites and assessment of renal innervation at 1 week post-procedure; and group C (n = 8) underwent ARG pacing before and 2 to 3 weeks after unilateral microwave renal denervation. RESULTS: ARG pace-capture responses were observed at paired discrete sites above the ipsilateral renal artery eliciting a change in mean arterial blood pressure of 22.2 (interquartile range [IQR]: 15.5 to 34.3 mm Hg; p < 0.001) with concurrent ipsilateral renal arterial vasoconstriction, change in main renal artery diameter of -0.42 mm (IQR: -0.64 to -0.24 mm; p < 0.0001), and without consistent contralateral renal vasoconstriction. Sympathetic ganglionic tissue was observed at ARG pace-capture sites, and ganglion ablation led to significant ipsilateral renal denervation. Circumferential renal denervation resulted in immediate and sustained abolition of ARP pacing-induced renal vasoconstriction and significant ipsilateral renal denervation. CONCLUSIONS: Transvascular ARG pace-capture is feasible and recognized by concurrent hypertensive and ipsilateral renal arterial vasoconstrictive responses. Abolition of ARG pacing-induced vasoconstriction may indicate successful renal sympathetic denervation and serve as a physiological procedural endpoint to guide transcatheter renal denervation.

Acute Hemorrhagic Leukoencephalopathy: Pathological Features and Cerebrospinal Fluid Cytokine Profiles.

BACKGROUND: Acute hemorrhagic leukoencephalopathy is a rare encephalopathy of unknown etiology, causing fulminant, hemorrhagic central nervous system demyelination with high mortality. It is unclear whether acute hemorrhagic leukoencephalopathy is an entirely distinct entity from acute disseminated encephalomyelitis. PATIENTS AND METHODS: We report two patients with rapidly progressive neurological illness resulting in raised intracranial pressure and coma, with biopsy-proven acute hemorrhagic leukoencephalopathy (perivascular hemorrhages and demyelination, predominantly neutrophil infiltrates). RESULTS: Acute cerebrospinal fluid showed pronounced T cell-associated cytokine elevation (interleukins 6, 8, and 17A) and CCL2 or CCL3, higher than in patients with acute disseminated encephalomyelitis, but no B cell-associated cytokine elevation. CONCLUSION: Improved understanding of the immune process may provide rationale for use of anticytokine biologic agents.