Safety of intrathecal delivery of recombinant human arylsulfatase A in children with metachromatic leukodystrophy: Results from a phase 1/2 clinical trial

BACKGROUND

Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by deficient arylsulfatase A (ASA) activity and characterized by neurological involvement that results in severe disability and premature death. We examined the safety and tolerability of intrathecally delivered recombinant human ASA (rhASA; SHP611, now TAK-611) in children with MLD (NCT01510028). Secondary endpoints included change in cerebrospinal fluid (CSF) sulfatide and lysosulfatide levels, and motor function (assessed by Gross Motor Function Measure-88 total score).

METHODS

Twenty-four children with MLD who experienced symptom onset aged ≤ 30 months were enrolled. Patients received rhASA every other week (EOW) for 38 weeks at 10, 30, or 100 mg (cohorts 1-3; n = 6 per cohort), or 100 mg manufactured using a revised process (cohort 4; n = 6).

RESULTS

No rhASA-related serious adverse events (SAEs) were observed; 25% of patients experienced an SAE related to the intrathecal device or drug delivery method. Mean CSF sulfatide and lysosulfatide levels fell to within normal ranges in both 100 mg cohorts following treatment. Although there was a general decline in motor function over time, there was a tendency towards a less pronounced decline in patients receiving 100 mg.

CONCLUSION

Intrathecal rhASA was generally well tolerated at doses up to 100 mg EOW. These preliminary data support further development of rhASA as a therapy for patients with MLD.

In vivo kinetic approach reveals slow SOD1 turnover in the CNS

Therapeutic strategies that target disease-associated transcripts are being developed for a variety of neurodegenerative syndromes. Protein levels change as a function of their half-life, a property that critically influences the timing and application of therapeutics. In addition, both protein kinetics and concentration may play important roles in neurodegeneration; therefore, it is essential to understand in vivo protein kinetics, including half-life. Here, we applied a stable isotope-labeling technique in combination with mass spectrometric detection and determined the in vivo kinetics of superoxide dismutase 1 (SOD1), mutation of which causes amyotrophic lateral sclerosis. Application of this method to human SOD1-expressing rats demonstrated that SOD1 is a long-lived protein, with a similar half-life in both the cerebral spinal fluid (CSF) and the CNS. Additionally, in these animals, the half-life of SOD1 was longest in the CNS when compared with other tissues. Evaluation of this method in human subjects demonstrated successful incorporation of the isotope label in the CSF and confirmed that SOD1 is a long-lived protein in the CSF of healthy individuals. Together, the results of this study provide important insight into SOD1 kinetics and support application of this technique to the design and implementation of clinical trials that target long-lived CNS proteins.

Determination of the role of injection site on the efficacy of intra-CSF enzyme replacement therapy in MPS IIIA mice

MPS IIIA is an inherited neurodegenerative lysosomal storage disorder characterized by cognitive impairment, sleep-wake cycle disturbance, speech difficulties, eventual mental regression and early death. Neuropathological changes include accumulation of heparan sulfate and glycolipids, neuroinflammation and degeneration. Pre-clinical animal studies indicate that replacement of the deficient enzyme, sulfamidase, via intra-cerebrospinal fluid (CSF) injection is a clinically-relevant treatment approach, reducing neuropathological changes and improving symptoms. Given that there are several routes of administration of enzyme into the CSF (intrathecal lumbar, cisternal and ventricular), determining the effectiveness of each injection strategy is crucial in order to provide the best outcome for patients. We delivered recombinant human sulfamidase (rhSGSH) to a congenic mouse model of MPS IIIA via each of the three routes. Mice were euthanized 24h or one-week post-injection; the distribution of enzyme within the brain and spinal cord parenchyma was investigated, and the impact on primary substrate levels and other pathological lesions determined. Both ventricular and cisternal injection of rhSGSH enable enzyme delivery to brain and spinal cord regions, with the former mediating large, statistically significant decreases in substrate levels and reducing microglial activation. The single lumbar CSF infusion permitted more restricted enzyme delivery, with no reduction in substrate levels and little change in other disease-related lesions in brain tissue. While the ventricular route is the most invasive of the three methods, this strategy may enable the widest distribution of enzyme within the brain, and thus requires further exploration.

Pharmacokinetics and bioavailability of a therapeutic enzyme (idursulfase) in cynomolgus monkeys after intrathecal and intravenous administration

Intravenous enzyme replacement therapy with iduronate-2-sulfatase is an approved treatment for Hunter syndrome, however, conventional intravenous delivery cannot treat the neurologic manifestations of the disease due to its limited central nervous system penetration. Intrathecal administration of iduronate-2-sulfatase for delivery to the central nervous system is currently under investigation. The objective of this study was to evaluate the pharmacokinetics of idursulfase in the central nervous system of cynomolgus monkeys (Macaca fasicularis) after intravenous and intrathecal administration. Twenty-seven monkeys, treatment-naïve to enzyme replacement therapy, were placed into 4 groups according to body weight: Group 1 was administered 0.5 mg/kg idursulfase intravenously, Groups 2-4 were administered an intrathecal formulation (1-, 10-, and 30-mg doses). Blood samples and cerebrospinal fluid (sampled at the cisterna magna or lumbar level) were collected at the same time points for 72 hours post dosing. Following intravenous administration, a high maximum serum concentration and rapid distribution of iduronate-2-sulfatase out of the central compartment were observed (elimination half-life: 4.3 hours). Iduronate-2-sulfatase exposure in the cerebrospinal fluid was limited, suggesting intravenous administration provided minimal penetration of the blood-brain barrier. Following intrathecal administration, a high maximum observed concentration was immediately noted and elimination half-life ranged between 7.8-10 hours and 5.9-6.7 hours (cisterna magna and lumbar sampling, respectively). Cerebrospinal fluid pharmacokinetic profiles at different doses of iduronate-2-sulfatase were similar and the dose/exposure relationship was proportional. After intrathecal administration, movement of iduronate-2-sulfatase from cerebrospinal fluid to serum was observed (systemic bioavailability was 40-83%). The clear penetration of iduronate-2-sulfatase into the cerebrospinal fluid and the dose response suggest that intrathecal delivery of iduronate-2-sulfatase may be suitable for treating the central nervous system manifestations associated with Hunter syndrome.

Open labeled, uncontrolled pharmacokinetic study of a single intramuscular hCG dose in healthy male volunteers

The current study was designed to compare blood and cerebrospinal fluid (CSF) pharmacokinetic characteristics of two forms of human chorionic gonadotropin (hCG): Pregnyl(R), derived from human urine, and Ovitrelle(R) a recombinant form. Two separate groups, each with six older male human subjects, were dosed with either form of the drug at 10,000 IU intramuscularly (IM), and followed over a 36-hour period. No significant difference in the serum level of hCG was observed for either preparation of hCG (Peak serum conc.: 316 +/- 53 vs. 270 +/- 60 at 12 hours, 311 +/- 38 vs. 321 +/- 60 IU/l at 24 hours; AUC: 10,053 +/- 1,268 vs. 8,793 +/- 1,768, Pregnyl and Ovitrelle, mean +/- SD, respectively). Additionally, both forms of circulating hCG distributed to the central nervous system (CNS) as manifest by an increased number of subjects whose CSF samples showed detectable levels of hCG in their CSF over a 36-hour period. Similarly, there was no significant difference between the two forms when distribution to the CSF was compared at 36 hours (2.0 and 1.2 IU/l; range 1.9 - 2.1 and 1 - 1.4 IU/l for Pregnyl and Ovitrelle, resp.). This preliminary study in normal human volunteers suggests that the two forms of hCG tested, Ovitrelle(R) and Pregnyl(R), when administered IM, distribute in a similar fashion into the circulation and CSF. Consequently, we conclude that these two drugs demonstrate no statistical significant difference with respect to the CSF.

Treatment failure related to intrathecal immunoglobulin M (IgM) synthesis, cerebrospinal fluid IgM, and interleukin-10 in patients with hemolymphatic-stage sleeping sickness

Human African trypanosomiasis treatment is stage dependent, but the tests used for staging are controversial. Central nervous system involvement and its relationship with suramin treatment failure were assessed in 60 patients with parasitologically confirmed hemolymphatic-stage Trypanosoma brucei gambiense infection (white blood cell count of or=1.9 mg/liter (OR, 11.7; 95% CI, 2.7 to 50), a CSF end titer by the LATEX/IgM assay of >or=2 (OR, 10.4; 95% CI, 2.5 to 44), and a CSF interleukin-10 concentration of >10 pg/ml (OR, 5; 95% CI, 1.3 to 20). The sensitivities of these markers for treatment failure ranged from 43 to 79%, and the specificities ranged from 74 to 93%. The results show that T. brucei gambiense-infected patients who have signs of neuroinflammation in CSF and who are treated with drugs recommended for use at the hemolymphatic stage are at risk of treatment failure. This highlights the need for the development and the evaluation of accurate point-of-care tests for the staging of human African trypanosomiasis.

Intrathecal enzyme replacement therapy: successful treatment of brain disease via the cerebrospinal fluid

Treatment of brain disease with recombinant proteins is difficult due to the blood-brain barrier. As an alternative to direct injections into the brain, we studied whether application of high concentrations of therapeutic enzymes via intrathecal (IT) injections could successfully drive uptake across the ependyma to treat brain disease. We studied IT enzyme replacement therapy with recombinant human iduronidase (rhIDU) in canine mucopolysaccharidosis I (MPS I, Hurler syndrome), a lysosomal storage disorder with brain and meningeal involvement. Monthly or quarterly IT treatment regimens with rhIDU achieved supranormal iduronidase enzyme levels in the brain, spinal cord, and spinal meninges. All regimens normalized total brain glycosaminoglycan (GAG) storage and reduced spinal meningeal GAG storage by 58-70%. The improvement in GAG storage levels persisted three months after the final IT dose. The successful use of enzyme therapy via the CSF represents a potentially useful approach for lysosomal storage disorders.

Inhibition of appetite by nasal leptin administration in rats

OBJECTIVE

Leptin inhibits appetite and reduces body weight. However, subcutaneous leptin administration is not very effective on weight reduction. The present studies were undertaken to test the hypotheses that nasally administered leptin effectively accesses to the brain and inhibits appetite.

METHODS

Recombinant leptin (0.5 mg/rat) was administered into the bilateral nasal spaces of rats (i.n.). Changes in serum immunoreactive leptin (IRL) and cerebrospinal fluid (CSF)-IRL concentrations after i.n. leptin administration were compared after intraperitoneal (i.p.) administration. The influence of 0.1 or 0.5% lysophosphatidylcholine (LPC) as an optimizer of leptin absorption was examined. The anorexic effects of i.n. leptin were compared with i.p. leptin in ad libitum fed rats.

RESULTS

The i.n. leptin increased CSF-IRL concentrations, although serum IRL concentrations of rats administered leptin i.n. were lower than those administered i.p. The addition of 0.1 and 0.5% LPC dose-dependently increased serum IRL concentrations, but did not modify CSF-IRL concentrations in i.n. leptin-treated rats. The i.n. leptin inhibited dark-time food consumption at 0-1 h and 3-6 h in ad libitum fed rats. In contrast, i.p. leptin reduced food consumption only for an hour. Phosphorylated signal transducer and activator of transcription (STAT) 3 immunoreactive cells increased in the arcuate nucleus (ARC) of the hypothalamus at 3 h only following i.n. leptin.

CONCLUSION

The present study demonstrated that i.n. leptin caused longer inhibition of appetite and phosphorylation of STAT3 in ARC. It is concluded that the trans-nasal route may be useful for the selective access of leptin to the brain in obese people.

D18G transthyretin is monomeric, aggregation prone, and not detectable in plasma and cerebrospinal fluid: a prescription for central nervous system amyloidosis?

Over 70 transthyretin (TTR) mutations facilitate amyloidosis in tissues other than the central nervous system (CNS). In contrast, the D18G TTR mutation in individuals of Hungarian descent leads to CNS amyloidosis. D18G forms inclusion bodies in Escherichia coli, unlike the other disease-associated TTR variants overexpressed to date. Denaturation and reconstitution of D18G from inclusion bodies afford a folded monomer that is destabilized by 3.1 kcal/mol relative to an engineered monomeric version of WT TTR. Since TTR tetramer dissociation is typically rate limiting for amyloid formation, the monomeric nature of D18G renders its amyloid formation rate 1000-fold faster than WT. It is perplexing that D18G does not lead to severe early onset systemic amyloidosis, given that it is the most destabilized TTR variant characterized to date, more so than variants exhibiting onset in the second decade. Instead, CNS impairment is observed in the fifth decade as the sole pathological manifestation; however, benign systemic deposition is also observed. Analysis of heterozygote D18G patient's serum and cerebrospinal fluid (CSF) detects only WT TTR, indicating that D18G is either rapidly degraded postsecretion or degraded within the cell prior to secretion, consistent with its inability to form hybrid tetramers with WT TTR. The nondetectable levels of D18G TTR in human plasma explain the absence of an early onset systemic disease. CNS disease may result owing to the sensitivity of the CNS to lower levels of D18G aggregate. Alternatively, or in addition, we speculate that a fraction of D18G made by the choroid plexus can be transiently tetramerized by the locally high thyroxine (T(4)) concentration, chaperoning it out into the CSF where it undergoes dissociation and amyloidogenesis due to the low T(4) CSF concentration. Selected small molecule tetramer stabilizers can transform D18G from a monomeric aggregation-prone state to a nonamyloidogenic tetramer, which may prove to be a useful therapeutic strategy against TTR-associated CNS amyloidosis.

Interleukin-2 gene therapy of chronic neuropathic pain

Previous research has revealed an antinociceptive (analgesic) effect of interleukin-2 (IL-2) in central and peripheral nervous systems. Unfortunately IL-2 is very short-lived in vivo, so it is impractical to apply IL-2 for analgesia in clinic. This study was performed to evaluate the effect of intrathecal delivery of human IL-2 gene on rat chronic neuropathic pain induced by chronic constriction injury of the sciatic nerve. Human IL-2 cDNA was cloned into pcDNA3 containing a cytomegalovirus promoter. The paw-withdrawal latency induced by radiant heat was used to measure the pain threshold. The results showed that recombinant human IL-2 had a dose-dependent antinociceptive effect, but that this only lasted for 10-25 min. The pcDNA3-IL-2 or pcDNA3-IL-2/lipofectamine complex in contrast also showed dose-dependent antinociceptive effects, but these reached a peak at day 2-3 and were maintained for up to 6 days. Liposome-mediated pcDNA3-IL-2 produced a more powerful antinociceptive effect than pcDNA3-IL-2 alone. The paw-withdrawal latencies were not affected by control treatments such as vehicle, lipofectamine, pcDNA3, or pcDNA3-lipofectamine. In the experimental groups, human IL-2 mRNA was detected by reverse transcription-polymerase chain reaction in the lumbar spinal pia mater, dorsal root ganglion, sciatic nerve, and spinal dorsal horn, but not in gastrocnemius muscle. The expressed IL-2 profile detected by western blot coincided with its mRNA profile except it was present in the spinal dorsal horn at a higher level. Furthermore, human IL-2 assayed by enzyme-linked immunosorbent assay in cerebrospinal fluid could still be detected at day 6, but lower than day 3. The antinociceptive effect of pcDNA3-IL-2 could be blocked by naloxone, showing some relationship of the antinociceptive effect produced by IL-2 gene to the opioid receptors. It is hoped that the new delivery approach of a single intrathecal injection of the IL-2 gene described here may be of some practical use as a part of a gene therapy for treating neuropathic pain.

Platelet-derived growth factor (PDGF-AB) like immune reactivity in serum and in cerebral spinal fluid following experimental subarachnoid haemorrhage in dogs

The aim of this study was to evaluate the following questions: Can the platelet-derived growth factor (PDGF-AB) be identified in the serum and cerebro spinal fluid (CSF) of dogs? Is there an increase in the concentration of PDGF-AB following experimental subarachnoid haemorrhage (SAH)? Is the increase in concentration related to the angiographic cerebral vasospasm of the basilar artery. The "double haemorrhage" model was applied in seven dogs to produce experimental SAH with determination of angiographic vasospasm in the basilar artery. Blood and CSF samples were taken on the first, third and eighth days. The analyses were performed with an ELISA human PDGF-AB antibody kit (quantikine human PDGF-AB, R&D Systems, Minneapolis, USA). The average PDGF-AB base value in the serum on the day before the SAH was 410.77 +/- 177.56 pg/ml, in the CSF it was 6.43 +/- 3.19 pg/ml. There was a significant (p = 0.05) increase in the concentration of PDGF-AB (third day 717.35 pg/ml, eighth day 918.07 pg/ml) in the serum of all animals. No significant increase was found in the CSF samples of any animal. In summary, a PDGF-AB like immune reactivity was found in the serum of dogs with the human PDGF-AB ELISA kit and the concentration of PDGF-AB in the serum increased after experimental SAH but not in CSF, but there was no relationship between the increase in PDGF-AB serum concentration and angiographic vasospasm.

Renal, central nervous system and pancreatic overexpression of recombinant soluble Crry in transgenic mice. A novel means of protection from complement-mediated injury

Crry is a potent complement regulator that inhibits classical and alternative pathway C3 convertases in rodents. We have produced transgenic animals expressing Crry as a recombinant soluble protein driven by the broadly active metallothionein-I promoter. These animals have high serum and urinary levels of rsCrry leading to inhibition of complement activity. In nephrotoxic serum nephritis (NSN), injected antibodies bind to glomeruli, leading to complement activation and subsequent glomerular injury and albuminuria. We have shown that rsCrry can block such injury and reduce albuminuria by as much as 75%. Corresponding to the reduction in albuminuria was the complete absence of C3 staining in glomeruli by immunofluorescence microscopy in 17/20 transgene positive animals. Support for a local source of protective rsCrry in this model is provided by the demonstration of Crry transgene mRNA in the glomerulus and a very high fractional excretion of rsCrry in the urine. Therefore, rsCrry expression markedly ameliorates an antibody-induced disease model in vivo. In addition, local synthesis of Crry in other organs that are targets of immune injury has been found. For example, Crry transgene mRNA is present throughout the central nervous system and in pancreatic islets. Thus, continuous complement inhibition at the C3 convertase step appears to be feasible and is effective in complement-mediated injury states. A number of disease models affecting these target organs can be tested using these mice.

Nonproteolytic neuroprotection by human recombinant tissue plasminogen activator

Human recombinant tissue plasminogen activator (tPA) may benefit ischemic stroke patients by dissolving clots. However, independent of thrombolysis, tPA may also have deleterious effects on neurons by promoting excitotoxicity. Zinc neurotoxicity has been shown to be an additional key mechanism in brain injuries. Hence, if tPA affects zinc neurotoxicity, this may provide additional insights into its effect on neuronal death. Independent of its proteolytic action, tPA markedly attenuated zinc-induced cell death in cortical culture, and, when injected into cerebrospinal fluid, also reduced kainate seizure-induced hippocampal neuronal death in adult rats.

A sandwich enzyme immunoassay for measuring AD7C-NTP as an Alzheimer's disease marker: AD7C test

A simple, fast, reliable, and specific immunoassay has been developed to detect and measure AD7C-NTP, a biochemical marker for Alzheimer's disease, in cerebrospinal fluid (CSF). This assay, called the AD7C Test, is an enzyme-linked sandwich immunoassay (ELSIA) using 96 well microtiter plates. The plate surface is coated with a monoclonal antibody (N3I4) which has a high affinity and specificity for AD7C-NTP, capturing it effectively from CSF samples. The detection was achieved using a polyclonal antibody (ADRI). Both N3I4 and ADRI were generated using recombinantly produced AD7C-NTP. The assay is highly sensitive (30-50 pg), linear to 2.0 ng (r2 > 0.99), and reproducible (C.V. < 10%). The utility of the assay has been demonstrated using CSF specimens from early Alzheimer's disease patients and age matched controls (sensitivity of 89% and specificity of 89%).

Analysis of the intrathecal immune response in neuroborreliosis to a sonicate antigen and three recombinant antigens of Borrelia burgdorferi sensu stricto

The intrathecal synthesis of borrelial-specific IgM- and IgG-antibodies was studied in 67 patients with neuroborreliosis and in 14 patients with neurosyphilis (controls). Antibody concentrations in serum and in the cerebrospinal fluid were determined by an enzyme immunoassay (EIA) using, as antigens, a sonicate of Borrelia burgdorferi, the recombinant 14 kDa flagellin fragment, the outer surface protein C (22 kDa), and the high molecular mass protein p83 (83 kDa). In the sonicate EIA, IgG- and/or IgM-antibodies to Borrelia burgdorferi in serum were detected in all patients with neuroborreliosis and in 71% of patients with neurosyphilis. Intrathecal synthesis of borrelial-specific IgG- and/or IgM-antibodies was demonstrated in 82% of patients with neuroborreliosis and in 71% of patients with neurosyphilis. Immunoglobulin G- and/or IgM-antibodies in serum against any of the recombinant antigens were detected in 92% of patients with neuroborreliosis and in none of those with neurosyphilis. Intrathecal synthesis of IgG- and/or IgM-antibodies to individual recombinant antigens was demonstrated in 67% of patients with neuroborreliosis and in none of those with neurosyphilis. The sensitivity of the recombinant antigens in serum was almost equal to that of the sonicate EIA, whereas the recombinant antigens were clearly less sensitive in the estimation of the intrathecal specific immune response. It was concluded that in suspected cases of neuroborreliosis, the estimation of high specific antibodies in the recombinant EIA will be helpful in confirming the diagnosis.

Kinetic and safety studies on intrathecally infused recombinant-methionyl human brain-derived neurotrophic factor in dogs

To define the kinetics and safety of spinally infused recombinant-methionyl human brain-derived neurotrophic factor (r-metHuBDNF), beagle dogs were prepared with lumbar intrathecal catheters passed through the cisternal membrane to the L1-L4 lumbar level. For kinetic studies, r-metHuBDNF was delivered by bolus or infusion through one catheter and lumbar CSF was sampled periodically through a second. As a lumbar bolus, r-metHuBDNF displayed a biphasic clearance with t(1/2)a = 0.7 hr and t(1/2)b = 7. 9 hr. Lumbar to cisternal concentrations after bolus delivery were approximately 60:1. For safety studies, dogs received continuous intrathecal infusion (2.4 ml/day) for 28 days of saline (n = 6), r-metHuBDNF at 200 (n = 6), 800 (n = 6), or 2000 (n = 7) microg/day. Control dogs showed no changes. Intrathecally infused r-metHuBDNF produced a dose-dependent increase in muscle tone and decreased coordination. Low-dose r-metHuBDNF was associated with moderate increases in muscle tone after 22-28 days of infusion. No clinically important changes were noted in rectal temperature, arterial pressure, respiration and heart rate, body weight, food consumption, stool or urine output, or change in blood chemistries measured throughout the study. Cisternal CSF protein and glucose sampled at 28 days were not different between dose groups and all cultures were negative. Histopathological examination of the spinal cord typically revealed some degree of chronic inflammation around the catheter, including fibrotic adhesions and focal accumulations of lymphoid and plasma cells, but these effects were not dose dependent. In other dogs receiving r-metHuBDNF (2000 or 4000 microg/day), termination of infusion resulted in significant recovery.

Regulation of brain interleukin-1 beta (IL-1 beta) system mRNAs in response to pathophysiological concentrations of IL-1 beta in the cerebrospinal fluid

Interleukin-1 beta (IL-1 beta) is released during pathophysiological processes. IL-1 beta induces neurological manifestations when administered into the cerebrospinal fluid (CSF) at pathophysiological concentrations detected during central nervous system (CNS) infections and other neurological disorders. In the present study, we investigated the regulation of the IL-1 beta system in the CNS in response to the chronic intracerebroventricular (icv) microinfusion of IL-1 beta at estimated pathophysiological concentrations in the CSF. IL-1 receptor type I (IL-1RI), IL-1 receptor antagonist (IL-1Ra), and IL-1 beta mRNAs were determined by sensitive RNase protection assays in brain target regions for IL-1 beta (cerebellum, parieto-frontal cortex, hippocampus, and midbrain). The results show that chronic icy microinfusion of IL-1 beta induced significant anorexia, increased the cerebellar IL-1RI mRNA content, increased IL-1Ra and IL-1 beta mRNAs levels in the cerebellum > midbrain > cortex > hippocampus, and induced profiles of IL-1RI mRNA, IL-1Ra mRNA, and IL-1 beta mRNA that were highly intercorrelated. On the other hand, levels of rat glyceraldehyde 3-phosphate dehydrogenase mRNA and 18S rRNA were fairly constant, and heat-inactivated IL-1 beta had no effect on food intake or on IL-1RI, IL-1Ra, and IL-1 beta mRNAs levels in any brain region. The data suggest the operation of an IL-1 beta feedback system (IL-1 beta/ IL-1Ra/IL-1RI) in brain regions. Dysregulation of the CNS IL-1 beta feedback system may have pathophysiological significance. This may be reflected, for example, in the pathogenicity and severity of neurological diseases, such as CNS infections.

Effect of a recombinant N-terminal fragment of bactericidal/permeability-increasing protein (rBPI23) on cerebrospinal fluid inflammation induced by endotoxin

Endotoxin triggers the subarachnoid inflammation of gram-negative meningitis. This study examined the ability of a recombinant N-terminal fragment of bactericidal/permeability-increasing protein (rBPI23) to block endotoxin-induced meningitis in rabbits. Intracisternal (ic) injection of 10-20 ng of meningococcal endotoxin induced high cerebrospinal fluid (CSF) concentrations of tumor necrosis factor (TNF) and CSF pleocytosis and increased CSF lactate concentrations. ic administration of rBPI23 significantly reduced meningococcal endotoxin-induced TNF release into CSF (P < .005), lactate concentrations (P < .001), and CSF white blood cell counts (P < .01). No such effect was observed in animals receiving intravenous rBPI23. Concentrations of rBPI23 in CSF were high after ic administration but low or undetectable after systemic administration. Thus, high concentrations of rBPI23 can effectively neutralize meningococcal endotoxin in CSF, but low CSF concentrations after systemic administration currently limit its potential usefulness as adjunctive drug treatment in gram-negative meningitis.

Immunoaffinity measurement of recombinant granulocyte colony stimulating factor in patients with chemotherapy-induced neutropenia

A high-performance immunoaffinity chromatographic technique has been developed for the measurement of recombinant human granulocyte colony stimulating factor in human patients receiving this agent, following neutropenia, arising from cancer chemotherapy. The technique employs a short, biocompatible polymer column packed with minute, antibody-coated glass beads. This system was applied to the analysis of recombinant human granulocyte colony stimulating factor in three different human body fluids. A reasonable degree of correlation was achieved when comparing the immunoaffinity technique to a conventional immunoassay, although the immunoaffinity technique displayed greater specificity.

Penetration of interleukin-6 across the murine blood-brain barrier

Interleukin-6 (IL-6) can alter brain function after peripheral administration, suggesting that it, like IL-1 alpha, IL-1 beta and TNF-alpha, might be able to cross the blood-brain barrier (BBB). We used multiple-time regression analysis to measure the unidirectional influx constant (Ki) into brain of radioactively labeled murine and human IL-6 given i.v. Ki values ranged from 3.05 to 4.54 (10(-4)) ml/g/min and were inhibited by unlabeled IL-6 but not IL-1 alpha or TNF-alpha, showing that the transport system for IL-6 is distinct from those for IL-1 alpha and TNF-alpha. Approximately 0.2% of the dose injected i.v. entered each gram of brain. The capillary depletion method showed that most of the IL-6 taken up by brain entered the parenchyma. However, only approximately 16% of the radioactivity recovered eluted as intact I-IL-6 in brain and approximately 50% in CSF after chromatographic separation by HPLC/Sephadex. The efflux rate for IL-6 injected into the lateral ventricle of the brain suggests that it enters the blood with the reabsorption of CSF. These results suggest that blood-borne IL-6 can reach sites behind the BBB, but that susceptibility to enzymatic degradation may limit contact time within the CNS.

Absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) from rat nasal mucosa

Nasal absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) was examined in the rat. The relative bioavailability of rhG-CSF for subcutaneous administration was approximately 2%, as evaluated from the immunologically active rhG-CSF concentration in rat plasma and the area under the curve (AUC) of the plasma rhG-CSF concentration versus time for 8 hr. Pharmacological availability relative to subcutaneous administration was determined from the increase in total blood leukocyte numbers. The pharmacological availability was 5-10%, determined from the AUC for the increased ratio of total leukocyte numbers versus time for 48 hr; it was slightly dependent on the pH and the osmotic pressure of the dosing solution. Accordingly, the plasma concentration of rhG-CSF did not always reflect its pharmacological effects. Relative bioavailability and pharmacological availability were increased about 23 times and 3 times, respectively, by polyoxyethylene 9-lauryl ether (Laureth-9), but no increase in availability occurred with sodium glycocholate. The increase in total leukocyte numbers was maintained during multiple rhG-CSF dosing, and the addition of Laureth-9 further increased the pharmacological effects of this agent. This study indicates that nasal administration of rhG-CSF is an effective parenteral administration route.

Determination of nerve growth factor concentrations in human samples by two-site immunoenzymometric assay and bioassay

Nerve growth factor is a neurotrophic protein which is known to act on sympathetic and sensory neurons and on the magnocellular cholinergic neurons of the basal forebrain. We quantified nerve growth factor in human tissue and body fluids by two methods, a rapid and sensitive two-site immunoenzymometric assay and a bioassay using dissociated chick dorsal root ganglion neurons. The two-site immunoenzymometric assay detects nerve growth factor in concentrations as low as 0.5-2.5 ng/l. Using a monoclonal antibody to mouse nerve growth factor, we found that the signal of the antibody for recombinant human nerve growth factor is about 60-90% of the signal for mouse nerve growth factor. As a control for the specificity of our data, a bioassay for nerve growth factor was performed and the results showed a good correlation. The highest nerve growth factor concentrations were found in sciatic nerve (2.5 ng/g wet weight), cardiac atrium muscle (1.5 ng/g wet weight) and in the central nervous system in the hippocampus (1.9 ng/g wet weight). Lower nerve growth factor concentrations were measured in human sera (0.2 ng/g wet weight). No nerve growth factor was detectable in cerebrospinal fluid. The distribution of human nerve growth factor-rich tissues is similar to that reported for rat tissues.

Nerve growth factor and a fibroblast growth factor-like neurotrophic activity in cerebrospinal fluid of brain injured human patients

We report here the presence of nerve growth factor (NGF) in the cerebrospinal fluid (CSF) of some brain-injured human patients soon after injury. The NGF was quantified against a recombinant human NGF standard in a two-site enzyme-linked immunoabsorbent assay using antibodies against murine B NGF. None of the samples collected more than 2 days after injury contained detectable levels of NGF. When the CSF was assayed for the ability to promote neurite outgrowth from PC12 cells, neurite outgrowth was reduced, but not completely blocked, by antibodies to B NGF, suggesting that there were other biologically active factors present. Fibroblast growth factor (FGF) also promotes neurite outgrowth in PC12 cells. In an initial screening for the presence of FGF, we employed PC12 cells and NR119 cells, PC12 variants in which recombinant human B NGF, but not recombinant human basic FGF, promotes neurite outgrowth. CSF from brain injury patients promoted greater neurite outgrowth from PC12 cells than from NR119 cells, suggesting that some of the biological activity associated with the injury CSF may be due a FGF. This possibility is further supported by the observation that the biological activity of the injury CSF significantly reduced by batch absorption with heparin Sepharose, suggesting the presence of a heparin binding neurotrophic factor. Neurotrophic factors appear in CSF as a consequence of diverse types of brain injury, including head trauma, intracerebral hemorrhage and subarachnoid hemorrhage. The appearance of these factors may reflect important common elements in the complex series of cellular changes occurring in response to acute brain injury.

Occurrence of interleukin-1 in cerebrospinal fluid of the conscious cat

Interleukin-1 (IL-1) is synthesized and released in response to various pathogens, including bacterial endotoxin, and is assigned an intermediary function in the genesis of fever. Its site of action in the central nervous system (CNS), however, is uncertain because the polypeptide is seemingly unable to cross the blood-brain barrier. Since several cell types, including astroglial, microglial, and vascular cells, can generate IL-1 upon appropriate stimulation, we examined whether IL-1 is formed in the CNS and may therefore serve as a messenger for systemic noxae. Experiments were conducted in the conscious cat and IL-1 was assayed in cerebrospinal fluid (CSF) from the third ventricle using a highly sensitive murine helper T cell line, D10.G4.1. In general, IL-1 levels were barely detectable in the absence of fever and did not increase at any stage of the sustained fever following intravenous injection of endotoxin (bolus) or crude monocyte supernate containing IL-1 (bolus plus infusion). In contrast, intracerebroventricular injection of a pyrogenic dose of endotoxin led to the appearance of IL-1 in the CSF. IL-1 levels reached maximal elevation during the uprise phase of the fever and declined thereafter. By the same route, natural or recombinant human IL-1 had no effect on CSF-IL-1 levels, though both preparations were as effective as endotoxin in eliciting fever. These findings confirm earlier data with radiolabelled pyrogens and indicate that the blood-brain barrier is impermeable to IL-1. We conclude that blood-borne IL-1 is likely to act at a discrete site outside the blood-brain barrier, possibly the organum vasculosum laminae terminalis. Centrally formed IL-1 may instead act diffusely in promoting fever and fever-related events (e.g. sleep).