[Analysis of 15 cases of toxic encephalopathy caused by acute benzene poisoning].

In this paper, the MRI manifestations of 15 patients with benzene toxic encephalopathy were analyzed, and the lesion location, shape, scope and signal were observed. The clinical manifestations of 15 patients were mainly central nervous system damage, and the MRI manifestations were characteristic, with a wide range of lesions, and the shapes were "sunflower-like", "flame-like", "bracket-like" and "butterfly-like", and the MRI signal was sheet-like long T(1), long T(2), fluid attenuated inversion recovery (FLAIR) sequence and diffusion weighted imaging (DWI) high signal, apparent diffusion coeffecient (ADC) map low, equal or high signals. When the patient's diagnosis is unclear, MRI examination may provide clinical basis for diagnosis.

Clinical features of patients with invasive Eikenella corrodens infections and microbiological characteristics of the causative isolates.

Clinical features of 43 cases of invasive Eikenella corrodens infections diagnosed at National Taiwan University Hospital during a 6-year period (1993-1998) were analyzed. The clinical syndromes included head and neck infection (56%), pulmonary infection (23%), intra-abdominal infection (14%), cutaneous infection (5%), skeletal infection (2%), endocarditis (2%), and pelvic abscess (2%). Nearly two-thirds of the patients (63%) had pre-existing diseases. Malignancy (35%), especially of the head and neck, was the most common underlying illness. More than half of the patients (56%) had associated factors predisposing to invasive Eikenella corrodens infection. Polymicrobial infections occurred in 28 (65%) patients, with two-thirds of the concurrent isolates being streptococci (66%). Five cases were fatal, with four deaths directly attributable to invasive Eikenella corrodens infection. Antimicrobial susceptibility testing and molecular typing were performed on 23 preserved Eikenella corrodens isolates. Antimicrobial susceptibility testing showed that Eikenella corrodens isolates were susceptible to penicillin, amoxicillin, cefoxitin, cefotaxime, cefepime, ciprofloxacin, and imipenem. The isolates were resistant to clindamycin, metronidazole, cephalothin, and cefuroxime. None of the 23 isolates produced beta-lactamase. Random amplified polymorphic DNA patterns of the 23 isolates were different, suggesting that different clones of Eikenella corrodens caused these infections.

U50488 inhibits HIV-1 expression in acutely infected monocyte-derived macrophages.

Opioids may play an immunomodulatory role in the pathogenesis of human immunodeficiency virus-1 (HIV-1) infection. Recently, synthetic kappa-opioid receptor (KOR) ligands have been found to have anti-human immunodeficiency virus type 1 activity in acutely infected brain macrophages. In the present study, we investigated whether the selective KOR ligand U50488 would exert such an anti-HIV-1 effect in acutely infected blood monocyte-derived macrophages (MDM). Treatment of acutely infected MDM with U50488 induced a concentration-dependent inhibition of HIV-1 expression. The dose--response relationship of U50488 was U-shaped with a peak effect observed at 10(-13) M, which was evident at both 7 and 14 days post-infection. The KOR antagonist nor-binaltorphimine blocked the anti-HIV-1 effect of U50488 by 73%, indicating involvement of a KOR-mediated mechanism. Also, expression of KOR mRNA and binding activity with a fluorescence-labeled KOR ligand supported the existence of KOR on MDM. Antibodies to the beta-chemokine, RANTES (regulated on activation normal T-cell expressed and secreted), but not to various other cytokines, blocked U50488 inhibition by 56% suggesting that the anti-HIV-1 effect of U50488 involved, in part, the production of RANTES by MDM. Taken together, these in vitro findings support the anti-HIV-1 property of U50488, and suggest that KOR ligands may have therapeutic potential for treating patients with acquired immunodeficiency syndrome.

Cytokine expression in the mouse brain in response to immune activation by Corynebacterium parvum.

Cytokine expression in the brain has been suggested to mediate various sickness behaviors. Here we report that intraperitoneal injection of a Corynebacterium parvum antigen in C57BL/6 mice was followed by prolonged upregulation of cytokines in the cerebral cortex and subcortical structures in a time course that coincided with reduced spontaneous running activity.

Cytokine effects on glutamate uptake by human astrocytes.

Glutamate uptake by astrocytes has been postulated to play a neuroprotective role during brain inflammation. Using primary human fetal astrocyte cultures, we investigated the influence of selected cytokines on glutamate uptake activity. Interleukin (IL)-1beta and tumor necrosis factor-alpha dose-dependently inhibited astrocyte glutamate uptake, whereas interferon (IFN)-gamma alone stimulated this activity. The nitric oxide synthase inhibitor, N(G)-monomethyl-L-arginine, blocked IL-1beta-mediated inhibition of glutamate uptake, suggesting involvement of nitric oxide in the effect of IL-1beta. IL-1 receptor antagonist protein totally reversed the inhibitory effect of cytokines, suggesting a critical role of IL-1beta. The anti-inflammatory cytokine IFN-beta blocked cytokine (IL-1beta plus IFN-gamma)-induced inhibition of glutamate uptake with a corresponding reduction in nitric oxide generation. Taken together, these findings suggest that proinflammatory cytokines inhibit astrocyte glutamate uptake by a mechanism involving nitric oxide, and that IFN-beta may exert a therapeutically beneficial effect by blocking cytokine-induced nitric oxide production in inflammatory diseases of the brain.

Inhibition of microglial cell RANTES production by IL-10 and TGF-beta.

Using human fetal microglial cell cultures, we found that the gram-negative bacterial cell wall component lipopolysaccharide (LPS) stimulated RANTES (regulated upon activation of normal T cell expressed and secreted) production through the protein kinase C signaling pathway and that activation of transcription nuclear factor (NF)-kappaB was required for this effect. Similarly, the proinflammatory cytokines interleukin (IL)-1beta and tumor necrosis factor-alpha dose-dependently stimulated microglial cell RANTES production via NF-kappaB activation. Anti-inflammatory cytokines, IL-10, and transforming growth factor (TGF)-beta sequentially inhibited LPS- and cytokine-induced microglial cell NF-kappaB activation, RANTES mRNA expression, and protein release. Proinflammatory cytokines but not LPS also stimulated RANTES production by human astrocytes. These findings demonstrate that human microglia synthesize RANTES in response to proinflammatory stimuli, and that the anti-inflammatory cytokines IL-10 and TGF-beta down-regulate the production of this beta-chemokine. These results may have important therapeutic implications for inflammatory diseases of the brain.

Cytokine regulation of human microglial cell IL-8 production.

IL-8 involvement in neutrophil activation and chemotaxis may be important in inflammatory responses within the central nervous system, secondary to meningitis, encephalitis, and traumatic injury. The source of IL-8 within the brain during these inflammatory processes, however, is unknown. To explore the role of microglia in the production of IL-8, human fetal microglia, which are the resident macrophages of the brain, were treated with LPS and pro- and anti-inflammatory cytokines to determine their effects on IL-8 production. We found that IL-8 protein levels increased in response to LPS or IL-1 beta, or to TNF-alpha, which also corresponded to elevated IL-8 mRNA levels by RT-PCR. Pretreatment with IL-4, IL-10, or TGF-beta 1 potently inhibited the stimulatory effects of these proinflammatory agents. These findings indicate that human microglia synthesize IL-8 in response to proinflammatory stimuli, and that anti-inflammatory cytokines down-regulate the production of this chemokine. These results may have important therapeutic implications for certain central nervous system insults involving inflammation.

Susceptibility to immunologically mediated fatigue in C57BL/6 versus Balb/c mice.

Proinflammatory cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha have been proposed to play a role in the pathogenesis of fatigue. In the present study we compared the susceptibility of two mouse strains to immunologically induced fatigue. Daily running of two strains of mice, Balb/c and C57BL/ 6, was assessed after a single injection of Corynebacterium parvum antigen (2 mg/mouse). Spontaneous running activity of each animal was compared to mean running distance prior to injection. To evaluate the involvement of cytokines in fatigue development, C57BL/6 mice were treated with antibodies to specific cytokines at the time of challenge with C. parvum antigen. Also, cytokine mRNA expression was analyzed in the brains of mice at different time periods after immunologic challenge. A significant difference in running activity between the two mice strains was observed after C. parvum antigen inoculation: C57BL/6 mice showing a greater (P < 0.05) reduction in running activity (relative to preinjection levels) and slower recovery to baseline than Balb/c mice. Injection of antibodies specific to either IL-1beta or TNF-alpha did not alter immunologically induced fatigue, suggesting a lack of involvement of these cytokines produced outside of the central nervous system (CNS). However, increased TNF-alpha and IL-1beta mRNA expression was found in the brains of C57BL/6 compared to that seen in Balb/c mice at 6, 10, and 15 days after C. parvum antigen injection. The elevated CNS cytokine mRNA expression corresponded to development of fatigue. These findings are consistent with the hypothesis that expression of proinflammatory cytokines within the CNS plays a role in the pathogenesis of immunologically mediated fatigue.

Tumor necrosis factor-alpha mediates the release of bioactive transforming growth factor-beta in murine microglial cell cultures.

Tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta produced by glial cells have been proposed bo play a role in various neurodenegerative diseases. The interaction of these two cytokines, however, is unknown. We tested the hypothesis that the TNF-alpha released from lipopolysaccharide (LPS)-treated murine microglial cells would stimulate the release of TGF-beta, which in turn would control TNF-alpha production. Treatment of murine microglial cell cultures with LPS resulted in an acute release of TNF-alpha (peak by 8 hr) followed by delayed release of bioactive TGF-beta (peak by 48 hr). Anti-TNF-alpha antibody significantly inhibited LPS-stimulated TGF-beta production, suggesting the involvement of TNF-alpha in TGF-beta production. Also, exogenous TNF-alpha induced in a dose-dependent fashion microglial cell expression of TGF-beta 1 mRNA and release of TGF-beta. Exogenous TGF-beta, on the other hand, suppressed LPS-stimulated TNF-alpha release. These findings suggest an autoregulation of microglial cell TNF-alpha production by TGF-beta which may limit inflammation-associated brain injury.

Differential regulation by cytokines of human astrocyte nitric oxide production.

Reactive nitrogen intermediates, such as nitric oxide (NO), play an important role in host-defense and injury. Human astrocytes released abundant NO upon stimulation with the pro-inflammatory cytokine interleukin (IL)-1 beta, which was potentiated by interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha. IL-1 receptor antagonist protein markedly attenuated astrocyte NO production. The anti-inflammatory cytokines IL-4 and IL-10 potently suppressed IL-1 beta plus IFN-gamma-stimulated NO, while transforming growth factor-beta preferentially inhibited IL-1 beta plus TNF-alpha-stimulated production of NO. These findings suggest that while IL-1 plays a key role in inducing astrocyte NO production, anti-inflammatory cytokines have the capacity to downregulate NO production by IL-1-stimulated astrocytes.

Thalidomide inhibits tumor necrosis factor-alpha production by lipopolysaccharide- and lipoarabinomannan-stimulated human microglial cells.

Tumor necrosis factor-alpha (TNF-alpha) is a pathogenic factor in bacterial meningitis. The effect of thalidomide on TNF-alpha production by microglia, the resident macrophages of the brain, was evaluated. In primary human fetal microglial cell cultures stimulated with lipopolysaccharide or lipoarabinomannan, thalidomide inhibited TNF-alpha release in a dose-dependent manner. The inhibitory effect of thalidomide was similar to that of dexamethasone, although expression of TNF-alpha mRNA in microglial cells was reduced only by thalidomide. The results of this in vitro study suggest that thalidomide could have therapeutic potential in gram-negative bacterial and tuberculous meningitis.

Tumor necrosis factor alpha upregulates human microglial cell production of interleukin-10 in vitro.

Interleukin (IL)-10 appears to play an important regulatory role in the systemic inflammatory response; however, production of IL-10 within the human central nervous system has not been described. Using cultures of human fetal microglial cells, the resident macrophages of the brain, we investigated the production and regulation of bioactive IL-10. Lipopolysaccharide stimulated acute release of tumor necrosis factor (TNF)-alpha (peak by 8 h) and delayed production of IL-10 (over a 48-h period) in microglial cell cultures. Treatment of microglial cell cultures with TNF-alpha and IL-6 resulted in a dose-dependent release of IL-10. These cytokines also induced expression of IL-10 mRNA. Treatment of microglial cell cultures with IL-10 markedly inhibited TNF-alpha and IL-6 production. These findings suggest that during inflammation within the brain, acute release of TNF-alpha and IL-6 by activated microglia could promote subsequent release of IL-10, which functions to minimize the potential neurotoxic effects of proinflammatory cytokines.

Upregulation of HIV-1 expression in cocultures of chronically infected promonocytes and human brain cells by dynorphin.

Using cocultures of human fetal brain cells and a chronically human immunodeficiency virus-1 (HIV-1)-infected promonocytic line U1, we investigated the effect of dynorphin, an endogenous opioid peptide found in the CNS, on upregulation of HIV-1 expression. Dynorphin and the synthetic kappa receptor agonist U50,488 promoted HIV-1 expression with a bell-shaped concentration-response relationship in which maximal effects were observed at 10(-13) and 10(-11) M, respectively. Pretreatment for 30 min with the kappa receptor antagonist nor-binaltorphimine completely blocked the stimulatory effect of dynorphin and U50,488. The involvement of cytokines on HIV-1 expression was tested. Dynorphin-induced upregulation of HIV-1 in the cocultures was largely blocked by antibodies to tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 but not by antibodies to IL-10. Also, dynorphin stimulated TNF-alpha and IL-6 in the brain cell cultures at both mRNA and protein levels, suggesting the involvement of these cytokines in opioid-induced HIV-1 expression. These findings suggest that endogenous opioid peptides such as dynorphin may have an immunomodulatory function in the CNS and could act as a cofactor in the neuropathogenesis of HIV-1.

Endogenous opioid peptides suppress cytokine-mediated upregulation of HIV-1 expression in the chronically infected promonocyte clone U1.

Opioid peptides appear to have an immunomodulatory activity. Using the chronically HIV-1-infected promonocyte clone U1, we investigated the effect of endogenous and synthetic opioid agonists on cytokine-induced HIV-1 expression. None of the endogenous or synthetic opioid agonists had an effect on constitutive HIV-1 expression. Opioid agonists such as methionine-enkephalin, dynorphin, and the kappa receptor agonist, U50,488, dose-dependently suppressed (> 40%) interleukin (IL)-6-induced upregulation of HIV-1 expression. Interestingly, opioid receptor antagonists (mu, delta, and kappa types) also inhibited (> 60%) IL-6-induced upregulation of HIV-1 expression. All opioid agonists and antagonists tested only modestly suppressed (< 20%) tumor necrosis factor-alpha-induced upregulation of HIV-1 expression in U1 cell cultures. These data suggest that certain opioid peptides alter an IL-6-induced signal transduction pathway which triggers HIV-1 expression in the chronically infected promonocyte U1.

Tumor necrosis factor-alpha production by human fetal microglial cells: regulation by other cytokines.

Tumor necrosis factor (TNF)-alpha has been postulated to play an important physiologic as well as pathologic role within the developing brain. In the present study, we found that human fetal microglial cells released abundant amounts of TNF-alpha upon stimulation with lipopolysaccharide (LPS). Treatment of microglial cell cultures with antibodies specific to interleukin (IL)-6, IL-10, and transforming growth factor (TGF)-beta augmented LPS-stimulated release of TNF-alpha. Each of these cytokines dose-dependently suppressed TNF-alpha release. Also, TNF-alpha mRNA expression was inhibited by each of these cytokines. By way of contrast, treatment of microglial cell cultures with IL-alpha or IL-1 beta alone or in the presence of LPS, resulted in increased release of TNF-alpha, and IL-1 stimulated the expression of TNF-alpha mRNA. These findings suggest that these cytokines are likely to modify the beneficial and harmful effects of TNF-alpha within the developing brain.

Cytokine modulation of murine microglial cell superoxide production.

Activated microglia may contribute to two opposite effects during inflammation within the central nervous system: host defense against microorganisms and neuronal injury. Each of these processes may be mediated by the generation of reactive oxygen intermediates by activated microglia. We investigated the effects of two proinflammatory cytokines, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha, and of the anti-inflammatory cytokine, transforming growth factor (TGF)-beta, on murine microglial cell superoxide (O2-) production upon stimulation with phorbol myristate acetate (PMA). Priming of microglia with IFN-gamma or TNF-alpha resulted in a dose-dependent enhancement of O2- release in response to PMA. The priming effects of these two cytokines were additive, suggesting that they acted by independent mechanisms. We also found that IFN-gamma and TNF-alpha stimulated the release of bioactive TGF-beta and that treatment of microglial cell cultures with TGF-beta antagonized the priming effects of IFN-gamma and TNF-alpha on O2- production. The results of this study have implications for understanding the mechanisms by which cytokines and microglia may contribute to host defense as well as to injury of the brain.

Priming effect of morphine on the production of tumor necrosis factor-alpha by microglia: implications in respiratory burst activity and human immunodeficiency virus-1 expression.

Opiates alter a variety of functional activities of the somatic immune system; within the central nervous system, however, their effects on immune responses are unknown. In the present study, we investigated the effect of morphine on the release of tumor necrosis factor (TNF)-alpha from murine neonatal microglia. Microglial cell cultures did not release TNF-alpha when incubated with morphine alone; however, an enhanced (P < .01) release of TNF-alpha was observed when cultures were first primed with morphine for 24 h and then stimulated with lipopolysaccharide. A bell-shaped dose-response curve was observed for the priming effect of morphine; maximal enhancement of TNF-alpha release (310 +/- 15% of control) was detected at a concentration of 10(-10) M morphine. Pretreatment of microglia for 30 min with opioid receptor antagonists (i.e. naloxone and beta-funaltrexamine) completely blocked the priming effect of morphine. In addition, morphine treatment amplified (P < .01) the priming effect of lipopolysaccharide on phorbol myristate acetate-triggered superoxide anion production by microglial cell cultures, and this effect was abrogated (P < .01) by anti-TNF-alpha antibody. Furthermore, culture supernatants derived from microglial cell cultures that had been treated with morphine before stimulation with lipopolysaccharide had an increased capacity to upregulate human immunodeficiency virus-1 expression in the latently infected promonocytic clone U1. This effect was also blocked by anti-TNF-alpha antibody. These findings suggest that morphine primes microglia for enhanced production of TNF-alpha which could alter several functional activities of these cells within the brain.