Effect of leukotriene inhibitors on evolution of experimental brain contusions.

AIMS: Leukotriene levels increase in cerebrospinal fluid (CSF) following controlled cortical impact (CCI) injury in rats. We investigated the impact of two different leukotriene inhibitors in the CCI model on CSF leukotriene levels, brain water content (BWC), brain swelling (BS) contusion size and cellular response. METHODS: 134 male Sprague Dawley rats were investigated at 4, 24 and 72 h after CCI for CSF leukotriene levels and BWC/BS, lesion size in T2-weighted magnetic resonance imaging and immunohistochemistry. Animals received vehicle, MK-886, an inhibitor of 5-lipoxygenase activating protein, or Boscari(®) , a mixture of boswellic acids, acting as competitive nonredox 5-lipoxygenase inhibitors before trauma and then every 8 h until sacrifice. RESULTS: The intracranial pressure (ICP) was unaffected by treatment. Boscari treatment reduced CSF leukotriene C4 increase by -45% at 4 h (P < 0.03) and increase of BWC and BS by 49% (P < 0.05) and -58% at 24 h. Treatment with both substances showed a reduction of lesion volume at 72 h by -21% (P < 0.01) in T(2) -weighted magnetic resonance imaging, which was reflected in a smaller lesion area determined from a NeuN labelled section (-17% to -20%, P < 0.05). Triple immunofluorescence and Fluoro-Jade B staining showed rarefaction of neurones, glia and vasculature in the contusion core, whereas in the pericontusional zone astro- and microglia were upregulated in the presence of dying neurones. Treatment resulted in an improved survival of NeuN labelled neurones in the pericontusional cortex (+15% to +20%, P < 0.05). CONCLUSIONS: Leukotriene inhibition should be further investigated as therapeutic option to counteract secondary growth of traumatic brain contusions and to possibly improve pericontusional neuronal survival.

Mediator release in cerebrospinal fluid of human immunodeficiency virus-positive patients with central nervous system involvement.

In this study we evaluated the release of some mediators of inflammatory reactions such as histamine (H), leukotriene B4 (LTB4), leukotriene C4 (LTC4) and prostaglandin D2 (PGD2) in the cerebrospinal fluid (CSF) of 15 patients with acquired immunodeficiency syndrome (AIDS), eight with opportunistic infections of the central nervous system (CNS) and seven without HIV-related neurological pathology, and of 25 HIV-negative control subjects with other neurological diseases. The cerebrospinal LTB4 level was increased in all the AIDS patients (mean 348 pg/ml); the control group revealed normal levels of LTB4 in the CSF (mean 63.2 pg/ml). The PGD2 level in the HIV-positive (mean 264 pg/ml) patients was higher than of the control subjects (mean 50 pg/ml), while low LTC4 levels were found both in the HIV-positive and control groups. We did not find any significant concentration of H in the CSF of either the HIV-positive or the control subjects. These findings may be due to the presence of chronic HIV infection or to the opportunistic infections of the CNS that so often occur in the latest stages of the disease.

Leukotrienes in brain: natural occurrence and induced changes.

Peptidoleukotrienes (SP-LTs) (both total product and individual LTC4 and LTE4 and LTB4 were measured by radioimmunoassay in cerebrospinal fluid (CSF) collected from the third ventricle of conscious cats. Total SP-LT was expressed as LTE4 after treating samples with crude gamma-glutamyltranspeptidase. Prostaglandin (PG) E2 and thromboxane (TX) B2, the stable metabolite of TXA2, were also assayed in part of the experiments. Under basal conditions, SP-LT and LTC4 were consistently measurable (respectively, 327 +/- 14 and 244 +/- 41 pg/ml), while native LTE4 was below the threshold of the assay (60-280 pg/ml) in most cases. LTB4 was barely detectable (30 +/- 2 pg/ml) or not detectable at all. PGE2 was normally less abundant than TXB2 (31 +/- 4 vs 281 +/- 47 pg/ml). Intracerebroventricular (i.c.v.) administration of arachidonic acid (40 microgram) caused a 4-fold increase in SP-LT levels which was relatively small and transient compared to PGE2 (76-fold) and TXB2 (23-fold), while there was no change in either native LTE4 or LTB4. A similar response was obtained with platelet-activating factor (PAF, 1 microgram i.c.v.), though SP-LT elevation (4-fold) was more persistent. A further rise in SP-LT (9-fold) was noted when PAF administration was preceded by indomethacin (500 microgram i.c.v.), whereas PAF effect was reversed by pretreatment with either the PAF antagonist, BN52021 (1 microgram i.c.v.), or the 5-lipoxygenase inhibitors, U-60,257 (75 micrograms i.c.v.) and L-651,392 (10 mg/kg p.o.). PAF was also effective in causing a 3-fold rise in LTC4. Unlike PAF, pyrogens (endotoxin i.c.v. or i.v.; interleukin-1 i.v.) at doses above threshold for fever had no effect on LT levels in CSF, both in the absence and presence of indomethacin pretreatment. We conclude that SP-LTs are a normal constituent of CSF, LTC4, being the major species. The response to PAF accords with a pathogenetic role of the compounds in inflammatory processes and the reactive changes to injury. No evidence was obtained for the involvement of SP-LTs in the central mechanism of fever.

Analysis of leukotrienes in cerebrospinal fluid of a reference population and patients with inborn errors of metabolism: further evidence for a pathognomonic profile in LTC(4)-synthesis deficiency.

Cysteinyl leukotrienes (LTC(4), LTD(4), LTE(4)) are potent lipid mediators derived from arachidonate in the 5-lipoxygenase pathway. Recently, the first inborn error of leukotriene synthesis, LTC(4)-synthesis deficiency, has been identified in association with a fatal developmental syndrome. The absence of leukotrienes in cerebrospinal fluid was one of the most striking biochemical findings in this disorder. We analysed leukotrienes in cerebrospinal fluid of patients with a broad spectrum of other well-defined inborn errors of metabolism, including glutathione synthetase deficiency (n=2), Zellweger syndrome (n=3), mitochondrial disorders (n=8), fatty acid oxidation defects (n=7), organic acidurias (n=7), neurotransmitter defects (n=5) and patients with non-specific neurological symptoms, as a reference population (n=120). The concentrations of leukotrienes were not related to age. Representative percentiles were calculated as reference intervals of each leukotriene. In all patients with an inborn error of metabolism concentration of cysteinyl leukotrienes and LTB(4) did not differ from the reference group. Our results indicate that absence of cysteinyl leukotrienes (<5 pg/ml) in association with normal or increased LTB(4) (50.0-67.3 pg/ml) is pathognomonic for LTC(4)-synthesis deficiency. The unique profile of leukotrienes in cerebrospinal fluid in this new disorder is primarily related to the defect and represents a new diagnostic approach.

Temporal profiles of cerebrospinal fluid leukotrienes, brain edema and inflammatory response following experimental brain injury.

The post-traumatic changes of leukotrienes LTC4, LTD4, LTE4, and LTB4 in cerebrospinal fluid of rats from 10 min to 7 days were investigated after controlled cortical impact in relation to brain edema and cellular inflammatory response. LTC4 increased five-fold at 4 h, normalized at 24 h, and showed another four-fold increase at 7 days. The same pattern was observed for LTD4 and LTE4. LTB4 however, behaved differently: concentrations were lower and levels peaked two-fold at 24 h. Edema in the injured hemisphere increased continuously up to 24 h without change contralaterally. Leukocyte infiltration, macrophage presence and microglia activation were most prominent at 24 h, 7 days and 24 h respectively. Leukotriene changes in CSF seem to reflect those in the affected tissue, with a time delay and in lower concentrations, and were not linearly correlated to brain edema. The initially high leukotriene levels are rather likely to contribute to the cytotoxic edema than to enhance a vasogenic edema component. The profile of LTB4 was parallel to the time course of leukocyte infiltration, indicating initiation of infiltration as well as prolonged production by leukocytes themselves. The second leukotriene peak at 7 days is likely to follow a different pathway and might be related to a production in macrophages or activated glia.

Eicosanoid levels in CSF of premature infants with posthemorrhagic hydrocephalus.

The cerebrospinal fluid (CSF) of 11 premature infants suffering from posthemorrhagic hydrocephalus was examined by radioimmunoassay for prostaglandin (PG) E2, PGF2 alpha, PGD2, 6-keto PGF1 alpha, thromboxane B2 (TxB2) and peptidoleukotrienes (LTC4/LTD4). The LTs were detected in the CSF of more of these patients (70%) than any of the other eicosanoids, and usually in the highest concentration. Among the 11 posthemorrhagic patients CSF eicosanoid levels were highest when determined soon after injury. Moreover, the variety of eicosanoids present, as well as concentrations, in these infants decreased with time. The types of eicosanoids most evident in the CSF of patients who required shunting were TxB2 and LTs, being present together in 5 of 6 (83%) of these infants. In contrast, 1 of 5 (20%) of the patients who did not require this neurosurgical intervention contained both TxB2 and LTs, the remaining having only one or neither eicosanoid. The highest average concentration for each eicosanoid studied was (pg/ml): PGE2, 628; PGF2 alpha, 985; PGD2, 1410; 6-keto PGF1 alpha, 544; TxB2, 486 and LTs, 1229. This study is the first to demonstrate that the CSF of preterm infants may contain a wide variety of eicosanoids and indicates that these lipids are a manifestation of neurological assault.

Levels of immunoreactive cysteinyl-leukotrienes in CSF after subarachnoid haemorrhage correlate with blood flow-velocity in TCD.

Lipid peroxidation and enhanced arachidonic acid metabolism is activated after blood-brain cell contact. Previous studies have indicated that cysteinyl-leukotrienes (cys-LT) have the capacity to constrict arterial vessels in vivo and in vitro suggesting their involvement in the pathogenesis of cerebral vasospasm. The purpose of this study was to measure the amount of cyst-LT in the cerebro-spinal fluid (CSF) in correlation with transcranial Doppler findings (TCD) in patients with aneurysmal subarachnoid haemorrhage (SAH). In all patients early surgery was performed. In the first cisternal CSF-sample which was already collected intra-operatively an initial peak of cys-LT was detected, followed by decreasing amounts of cys-LT during the next 5 days. The CSF-levels of immunoreactive cys-LT were significantly higher in those patients who showed signs of vasospasm on transcranial Doppler sonography (TCD) (p < 0.001). Normalization of TCD values was accompanied by decreasing levels of CSF-cys-LT. We found a significant correlation between the amounts of immunoreactive cys-LT in cerebrospinal fluid and cerebral vasospasm measured by TCD.