SllmmsLryEosinophil accumulation is a prominent feature of allergic inflammatory reactions, such as those occurring in the lung of the allergic asthmatic, but the endogenous chemoattractants involved have not been identified. We have investigated this in an established model of allergic inflammation, using in vivo systems both to generate and assay relevant activity. Bronchoalveolar lavage (BAL) fluid was taken from sensitized guinea pigs at intervals after aerosol challenge with ovalbumin. BAL fluid was injected intradermally in unsensitized assay guinea pigs and the accumulation of intravenously injected 111In-eosinophils was measured. Activity was detected at 30 min after allergen challenge, peaking from 3 to 6 h and declining to low levels by 24 h. 3-h BAL fluid was purified using high performance liquid chromatography techniques in conjunction with the skin assay. Microsequencing revealed a novel protein from the C-C branch of the platelet factor 4 superfamily of chemotactic cytokines. The protein, "eotaxin," exhibits homology of 53% with human MCP-1, 44% with guinea pig MCP-1, 31% with human MIP-loe, and 26% with human RANTES. Laser desorption time of flight mass analysis gave four different signals (8.15, 8.38, 8.81, and 9.03 kD), probably reflecting differential O-glycosylation. Eotaxin was highly potent, inducing substantial 111In-eosinophil accumulation at a 1-2-pmol dose in the skin, but did not induce significant 111In-neutrophil accumulation. Eotaxin was a potent stimulator of both guinea pig and human eosinophils in vitro. Human recombinant RANTES, MIP-lcr, and MCP-1 were all inactive in inducing ~11In-eosinophil accumulation in guinea pig skin; however, evidence was obtained that eotaxin shares a binding site with P.ANTES on guinea pig eosinophils. This is the first description of a potent eosinophil chemoattractant cytokine generated in vivo and suggests the possibility that similar molecules may be important in the human asthmatic lung.

The farnesoid X receptor͞bile acid receptor (FXR) is a recently discovered member of the nuclear hormone superfamily. FXR ligands have been proposed as targets in cardiovascular disease, regulating cholesterol metabolism and bile acid transport and metabolism in the liver and gastrointestinal tract. When we used a human cardiovascular tissue array, we found that FXR is expressed in a variety of normal and pathological human tissue. Particularly high levels of FXR were found in the vasculature and in a number of different metastatic cancers, as well as the previously identified target tissues of the liver, small intestine, and kidney. In vitro, FXR is present in rat and human vascular smooth muscle cells. When treated with a range of FXR ligands, vascular smooth muscle cells undergo apoptosis in a manner that correlates with the ligands' ability to activate FXR. Furthermore, FXR activators induce mRNA for the FXR target genes, phospholipid transfer protein, and the small heterodimer partner. FXR therefore is a functional protein in the vasculature that may provide a direct target for the treatment of proliferative and dyslipidaemic diseases.

Bile acids are present at high concentrations in breast cysts and in the plasma of postmenopausal women with breast cancer. The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that regulates bile acid homeostasis. FXR was detected in normal and tumor breast tissue, with a high level of expression in ductal epithelial cells of normal breast and infiltrating ductal carcinoma cells. FXR was also present in the human breast carcinoma cells, MCF-7 and MDA-MB-468. Activation of FXR by high concentrations of ligands induced MCF-7 and MDA-MB-468 apoptosis. At lower concentrations that had no direct effect on viability, the FXR agonist GW4064 induced expression of mRNA for the FXR target genes, small heterodimer partner (SHP), intestinal bile acid binding protein, and multidrug resistance-associated protein 2 (MRP-2), and repressed the expression of the SHP target gene aromatase. In contrast to MRP-2, mRNA for the breast cancer target genes MDR-3, MRP-1, and solute carrier transporter 7A5 were decreased. Although multidrug resistance transporters were regulated and are known FXR target genes, GW4064 had no effect on the cell death induced by the anticancer drug paclitaxel. Our findings show for the first time that FXR is expressed in breast cancer tissue and has multiple properties that could be used for the treatment of breast cancer.

No abstract

Murine prion disease is accompanied by a modified inflammatory response characterized by early but prolonged microglial activation and T-lymphocyte recruitment. In this model, we look at the profile of cytokine production, particularly IL-1beta. Mice inoculated with prion-infected brain homogenate show typical signs of prion disease. We were unable to detect any IL-1beta using immunohistochemistry, with various fixation protocols, or ELISA between 8 and 24 wk post-inoculation. Also, there was no increase in mRNA for IL-1beta, IL-6, IFNgamma, and iNOS as measured by quantitative RT-PCR. Using the same procedures and examining tissues at the same time, IL-1beta immunostaining was detected in infiltrating inflammatory cells in mouse brains injected with LPS or in a delayed-type hypersensitivity response in the brain. Soluble IL-1beta was also increased, as measured by ELISA, and there was an increase in mRNA species for IL-1beta, IL-6, TNFalpha but not IFNgamma or iNOS in these brains. These data reveal that chronic neurodegeneration seen in prion disease does not induce production of a range of proinflammatory mediators despite showing marked microglial activation and raise the question as to whether IL-1beta would exacerbate the neurodegeneration as it does in acute neurodegeneration following head injury and stroke.

We have previously demonstrated that amyloid beta (Abeta) peptide is acutely toxic to retinal neurones in vivo and that this toxicity is mediated by an indirect mechanism. We have now extended these studies to look at the chronic effect of intravitreal injection of Abeta peptides on retinal ganglion cells (RGC), the projection neurones of the retina and the glial cell response. 5 months after injection of Abeta1-42 or Abeta42-1 there was no significant reduction in RGC densities but there was a significant reduction in the retinal surface area after both peptides. Phosphate-buffered saline (PBS) injection had no effect on retinal size or RGC density. There was a pronounced reduction in the number of large RGCs with a concomitant significant increase in medium and small RGCs. There was no change in cell sizes 5 months after injection with PBS. At 5 months after injection of both peptides, there was marked activation of Muller glial cells and microglia. There was also expression of the major histocompatibility complex (MHC) class II molecule on some of the microglial cells but we saw no evidence of T-cell infiltration into the injected retinas. In order to elucidate potential toxic mechanisms, we have looked at levels of glutamine synthetase and nitric oxide synthase. As early as 2 days after injection we noted that activation of Muller glia was associated with a decrease in glutamine synthetase immuno-reactivity but there was no detectable expression of inducible nitric oxide synthase in any retinal cells. These results suggest that chronic activation of glial cells induced by Abeta peptides may result in chronic atrophy of projection neurones in the rat retina.

Nitric oxide (-NO) synth:~-~ ~ NOS) ~ctivity in suboell~:la; traclions from cultured cndothclial cells (EC) and lipopolysaccharide-activated J774.2 monocyte/macrophage~ ~ ~_~ investigated by monitoring the -NO-mediated increase in intraceilalar cyclic GMP in LLC-PK~ pig kidney epithelial cells. The constitutive NOS in EC (NOS,) was largely membrane-bound, whereas the induc~.ble SOS in $774.2 cells (NOS,) was equally distributed among cytosol and membrane(s). Both the cytosolic NOS, in EC and the membrane-bound NOS, in J774.2 cells were strictly Ca2"-dependent, whereas the membrane-bound NOSe in EC and the cytosolic NOS, in J774.2 cells were not. L-Homoarginine and L-arginine-conlaining small peptides, such as L-arginyI-L-phenylalanine, replaced L-arginine as a substrate for the NOS, in EC and the CaZ*-independent SOS, in J774.2 cells, but nol the Ca2"-dependent NOS,. Thus, irrespective of their intracellular Iocalisat~on, at lec.~, three isoforrr~s of NOS exist, which can be differentiated by their substrate specificity and Ca2"-dependeney.

1 The sensory neuropeptide substance P (SP), when released from sensory nerves, has been implicated in the development of neurogenic inflammation. In the present study, using an in vivo model system, we have characterized and investigated the mechanisms underlying SP‐induced leukocyte accumulation and oedema formation in the guinea‐pig.2 Intradermaly injected SP (i.d., 10−13‐10−9mol per site), induced a dose‐ and time‐dependent accumulation of 111In‐neutrophils, 111In‐eosinophils and oedema formation as measured by the local accumulation of i.v. injected l25I‐albumin. The leukocyte accumulation evoked by SP was significant at 10−10 and 10−9mol per site, whereas oedema formation was significant at the lowest dose tested (10−13mol per site).3 The NK1 receptor antagonists, CP‐96,345 (1 mgkg−1, i.v.) and RP‐67,580 (10 μg per site, i.d.), significantly attenuated the oedema formation induced by the lower doses of SP. Oedema formation and leukocyte accumulation induced by 10−9mol per site SP were unaffected by either antagonist.4 SP‐elicited responses were not significantly affected by the platelet activating factor (PAF) receptor antagonist, UK‐74,505 (2.5 mgkg−1, i.v.) or the H1 histamine receptor antagonist, chlorpheniramine (10−8mol per site, i.d.). However, the 111In‐eosinophil accumulation, but not the 111In‐neutrophil accumulation or oedema formation, induced by SP was significantly inhibited by the specific 5lipoxygenase (5‐LO) inhibitor, ZM‐230,487 (10−8 mol per site, i.d.).5 The accumulation of both 111In‐neutrophils and 111In‐eosinophils induced by SP was abolished in guinea‐pigs treated i.v. with an anti‐CD 18 monoclonal antibody 6.5E F(ab′)2 (2.5 mgkg−1). The oedema response was unaffected in these animals.6 These results suggest that SP‐induced inflammatory events may be mediated via two mechanisms involving NK1 receptor‐dependent and independent pathways. Oedema formation induced by the lower doses of SP may be mediated via the direct activation of NK1 receptors whilst, at higher doses, oedema formation and leukocyte accumulation may be mediated via the release of secondary mediators, possibly mast cell derived, with 5‐LO products playing an important role in the leukocyte infiltration. The leukocyte accumulation, but not the oedema induced by SP, is dependent on the expression of the CD 18 antigen on leukocytes.