Véronique Taupin

Increase in IL-6, IL-1 and TNF levels in rat brain following traumatic lesion: Influence of pre- and post-traumatic treatment with Ro5 4864, a peripheral-type (p site) benzodiazepine ligand

The effects of fluid percussion trauma on brain interleukin (IL)-6, IL-1 and tumor necrosis factor-alpha (TNF-alpha) levels have been studied. In the cortex and hippocampus of control and sham-operated rats, the levels of these cytokines were very low (below 4 units/mg protein) and constant. IL-6 and IL-1 levels in the ipsilateral cortex increased rapidly following trauma to reach a maximum of 350 and 16 units/mg protein, respectively, 8 h after the lesion, remained elevated until 18 h and decreased thereafter to basal values. TNF-alpha levels were maximally elevated (12 units/mg protein) at 3 h and 8 h and returned to basal values by 18 h. Qualitatively similar changes, but with 25-80-fold smaller amplitude, were seen in the contralateral cortex and in the ipsi- and contralateral hippocampus. The levels of IL-6 in the plasma of sham-operated and lesioned rats were only slightly elevated, whereas IL-1 and TNF-alpha were undetectable. Histological studies of brain tissue at early stages after trauma demonstrated an acute hemorrhage associated with neutrophil invasion. The administration of Ro5 4864 (0.5 mg/kg i.p.), a specific ligand of p (peripheral-type benzodiazepine) binding sites, did not result in any significant effect on the levels of IL-6, IL-1 or TNF-alpha in the brain of control or sham-operated animals. However, when administered 24 h before or 15 min after trauma, this benzodiazepine enhanced the increase of these cytokines by 2-4-fold in the ipsilateral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Fractalkine modulates TNF‐α secretion and neurotoxicity induced by microglial activation

Among the chemokine family, fractalkine shows unusual properties: it exists as a membrane‐bound and soluble protein, and both fractalkine and its receptor CX3CR1 are expressed predominantly in the central nervous system. In rat cell culture models, the chemokine fractalkine was expressed in neurons and microglia, but not in astrocytes and its receptor exclusively localized to microglial cells, where its expression was downregulated by treatment with the bacterial endotoxin (LPS). In microglial cultures, LPS (10 ng/ml) induced a marked increase in the release of the proinflammatory cytokine tumor necrosis factor‐α (TNF‐α). The effects of LPS on TNF‐α secretion were partially blocked (30%) by fractalkine and the effects of fractalkine were reversed by a polyclonal anti‐fractalkine antibody. When microglial‐associated fractalkine was neutralized by anti‐fractalkine antibody, the LPS response was increased by 80%, suggesting tonic activation of microglial fractalkine receptors by endogenous fractalkine. The effects of the antibody were antagonized by the addition of fractalkine. LPS‐activated microglia were neurotoxic when added to neuronal hippocampal culture, producing 20% neuronal death, as measured by NeuN‐positive cell counting. An anti‐fractalkine antibody produced neurotoxic effects of similar magnitude in this co‐culture system and also markedly potentiated the neurotoxic effects of LPS‐activated microglia (40% neuronal death). These results suggest that endogenous fractalkine might act tonically as an anti‐inflammatory chemokine in cerebral tissue through its ability to control and suppress certain aspects of microglial activation. These data may have relevance to degenerative conditions such as multiple sclerosis, in which cerebral inflammatory processes may be activated. GLIA 29:305–315, 2000.

G-CSF Therapy of Ongoing Experimental Allergic Encephalomyelitis Via Chemokine- and Cytokine-Based Immune Deviation

Converging evidence that G-CSF, the hemopoietic growth factor of the myeloid lineage, also exerts anti-inflammatory and pro-Th2 effects, prompted us to evaluate its direct therapeutic potential in autoimmune diseases. Here we report a novel activity of G-CSF in experimental allergic encephalomyelitis, a murine model for multiple sclerosis, driven by Th1-oriented autoaggressive cells. A short 7-day treatment with G-CSF, initiated at the onset of clinical signs, provided durable protection from experimental autoimmune encephalomyelitis. G-CSF-treated mice displayed limited demyelination, reduced recruitment of T cells to the CNS, and very discrete autoimmune inflammation, as well as barely detectable CNS mRNA levels of cytokines and chemokines. In the periphery, G-CSF treatment triggered an imbalance in the production by macrophages as well as autoreactive splenocytes of macrophage inflammatory protein-1α and monocyte chemoattractant protein-1, the prototypical pro-Th1 and pro-Th2 CC chemokines, respectively. This chemokine imbalance was associated with an immune deviation of the autoreactive response, with reduced IFN-γ and increased IL-4 and TGF-β1 levels. Moreover, G-CSF limited the production of TNF-α, a cytokine also associated with early CNS infiltration and neurological deficit. These findings support the potential application of G-CSF in the treatment of human autoimmune diseases such as multiple sclerosis, taking advantage of the wide clinical favorable experience with this molecule.

Benzodiazepine anethesia in humans modulates the interleukin-1β, tumor necrosis factor-α and interleukin-6 responses of blood monocytes

Abstract The influence of sedative and anxiolytic benzodiazepines on human monocyte function was assessed in 11 patients undergoing anesthesia prior to control endoscopy of the urinary tract. A single i.v. injection of 0.08 mg/kg midazolam induced a marked and delayed inhibition of the lipopolysaccharide-induced production of interleukin-1β, tumor necrosis factor-α and interleukin-6 by monocytes isolated from peripheral blood. Corticosteroids were not responsible for the observed immunosuppression. These studies demonstrate that, when administered in man, benzodiazepines markedly alter the capacity of monocytes to synthetize major mediators of the host inflammatory response.

Regulation of neural and peripheral cytokine production by benzodiazepines and endogenous anxiogenic peptides.

Our search to understand the molecular links between immune and nervous systems has led us to propose that central benzodiazepine receptors (CBR) and peripheral benzodiazepine receptors (PBR) could represent an integrative network whereby endogenous ligands could modulate anxiety as well as immune functions 1. Among the molecular messengers that are involved not only in communication within cells of the immune system but also in information exchange between several integrated systems and particularly with the nervous system, are the cytokines. Benzodiazepine ligands modulate the production of cytokines and this interaction can take place at the periphery as well as within brain. In the present paper, we demonstrate that picomolar concentrations of triakontatetraneuropeptide (TTN), the major processing form of diazepam binding inhibitor (DBI), an endogenous peptide ligand of the benzodiazepine receptor, is able to modulate the gene expression of several pro-inflammatory cytokines by human monocytes2. Furthermore, an in vivo injection of a pharmacological ligand specific for the peripheral receptor significantly modulates the cytokine levels induced by fluid percussion trauma in rat brain3.