IL-8 reduced tumorigenicity of human ovarian cancer in vivo due to neutrophil infiltration.

Paclitaxel is a frontline therapy for ovarian cancer. Our laboratory has shown that paclitaxel induces IL-8, a member of the C-X-C family of chemokines, in subsets of human ovarian cancer cells. However, the critical issue concerns the biological significance of this chemokine in human ovarian cancer. To study the influence of IL-8 on tumor growth, human ovarian cancer cell lines were transfected with an expression vector for human IL-8 and tested for their ability to form tumors in nude mice. IL-8 expression by the transfected cells did not alter their growth properties in vitro. In contrast, tumor growth in vivo was significantly attenuated in animals receiving IL-8-expressing cells when compared with mice injected with control cells. As additional evidence that IL-8 is a crucial factor in tumor growth, it was noted that ovarian cell lines in which constitutive IL-8 expression is elevated did not form tumors. Injection of neutralizing Ab to IL-8 reverted the phenotype and caused tumor growth in vivo. Examination of tissue from the inoculation site revealed a dramatically elevated cellularity, containing neutrophils and macrophages, in mice receiving IL-8-expressing tumor cells. These results suggest that IL-8 production by human ovarian tumor cells can play a role in reducing the rate of tumor growth; this effect may be mediated by the increased targeting of neutrophil and other mononuclear cells to the tumor injection site. These studies indicate a role for IL-8 in ovarian cancer control and suggest that chemotherapy-induced IL-8 may have a positive role in controlling tumor growth.

Differential selectivity of CIITA promoter activation by IFN-gamma and IRF-1 in astrocytes and macrophages: CIITA promoter activation is not affected by TNF-alpha.

During demyelinating disease of the central nervous system (CNS), locally elevated cytokine levels may induce upregulation of MHC class II molecules on otherwise low expressing or negative cell types such as microglia and astrocytes, since IFN-gamma has been shown to induce MHC class II expression on these cell types in vitro. While many transcription factors are involved with MHC class II expression, only the class II transactivator (CIITA) is tightly coordinated with IFN-gamma-inducibility. Control of CIITA gene expression is complex, involving four distinct promoters, two of which (promoters III and IV) are IFN-gamma-inducible in certain cell types. Here we demonstrate that IFN-gamma treatment of rat astrocytes induces only CIITA promoter IV activity in contrast to the murine macrophage cell line RAW 264.7 that uses both IFN-gamma-inducible promoters. In contrast to previously published reports, promoter IV activation is completely dependent upon an intact interferon regulatory factor-1 (IRF-1) but not STAT binding site using promoter constructs specifically mutated at these positions. Importantly, while TNF-alpha is able to synergize with IFN-gamma to increase astrocyte MHC class II expression in vitro, we show that treatment of rat astrocytes with TNF-alpha has no effect on CIITA promoter activity. These data demonstrate that TNF-alpha augments MHC class II expression through a mechanism downstream or independent of CIITA induction.

Differential regulation of cytokine-induced major histocompatibility complex class II expression and nitric oxide release in rat microglia and astrocytes by effectors of tyrosine kinase, protein kinase C, and cAMP.

Two glial cell populations of the CNS, astrocytes and microglia, were examined for expression of two immunologically important molecules, MHC class II and nitric oxide (NO), following treatment with cytokines. IFN-gamma induced both molecules in microglia at substantially higher levels than astrocytes. The addition of TNF-alpha to IFN-gamma elevated class II expression and NO in both cells. Genistein, an inhibitor of tyrosine kinases, and calphostin, an inhibitor of protein kinase C, diminished cytokine induction of class II MHC and NO in both glial populations. Forskolin was most effective in inhibiting class II MHC expression, but had little inhibitory effect on NO production. These results indicate microglia are more effective than astrocytes in producing cell-associated and secreted immune mediators in response to IFN-gamma and or TNF-alpha and multiple parallel, but distinct, signaling events are required for cytokine induced class II MHC or NO production.

Prenatal expression of 5-HT1C and 5-HT2 receptors in the rat central nervous system.

The expression of mRNAs for two 5-HT receptors (5-HT1C, 5-HT2) has been investigated by evaluating in situ hybridization in the prenatal rat CNS. At Embryonic Day 14 (E14), the highest signal for 5-HT1C was found in the choroid plexus, while the marginal/intermediate (m/i) zones of the midbrain, brain stem (including monoaminergic groups), and spinal cord also displayed label. By E18-21 a number of more rostral regions contained transcript, including the hippocampus (CA1), in addition to more intense signal in midbrain, brain stem, and spinal cord. Expression in the choroid plexus appeared to peak between E16-E18, although considerable hybridization signal remained at E21. 5-HT2 transcripts were also detected at E14. Label was present in m/i zones of the midbrain and in a number of other areas. In comparison to 5-HT1C, 5-HT2 mRNA was distributed over a wider rostral-caudal extent at this age. As with 5-HT1C mRNA, signal increased over rostral and brain stem areas at late gestational ages with significant labeling appearing in the olfactory bulb, cerebellum, cortical plate and subplate, hippocampus (dentate gyrus), and monoaminergic nuclei. 5-HT1C and 5-HT2 receptor transcripts were also present over the meninges at E16 and may represent transient expression of these receptors. These expression patterns in the embryonic rat brain, in conjunction with previous evidence indicating that 5-HT can act as a differentiation signal for target neurons, suggests that prenatal 5-HT receptors are positioned to play a role in the prenatal development of the CNS.

Progressive metabolite changes in individual human muscle fibers with increasing work rates.

Muscle biopsies were obtained from vastus lateralis muscles of four volunteers exercising at increasing work rates on a bicycle ergometer. Samples were taken at rest (t1), after a work load 23% below the blood lactate threshold (t2), 23% above this threshold (t3), and at exhaustion (t4). Individual muscle fibers were typed by their lactate dehydrogenase and adenylokinase levels and assayed for lactate, glucose-6-phosphate, and malate, (which preliminary data indicated to be the most responsive to increased activity) as well as ATP and phosphocreatine. The results in three of the four cases indicated that by the time of the t2 sample, almost all fibers, regardless of type, had been recruited. Additionally, there were no major differences in lactate concentration between type 1 and 2 fibers from muscle samples taken at t1, t2, and t3. It is concluded that in a muscle with fast-twitch glycolytic and slow-twitch oxidative fibers, all fibers share in the contraction to a substantial degree, even at moderate work loads, and that both the type 1 and 2 fibers contribute significantly to the initial rise in blood lactate during a graded exercise task. Metabolite responses in type 2 fibers differed in certain respects among the four participants. This is attributed to differences in their training backgrounds and consequent differences in type 2 fiber oxidative enzyme levels.

The distribution of choline acetyltransferase in the rat amygdaloid complex and adjacent cortical areas, as determined by quantitative micro-assay and immunohistochemistry.

The distribution of choline acetyltransferase (ChAT) within the amygdaloid complex has been studied to evaluate what should primarily represent the terminal field of the cholinergic projection from the basal forebrain. Two currently available methods have been combined for the comparison: immunohistochemistry with a monoclonal antibody against ChAT, by a double peroxidase-antiperoxidase procedure, and quantitative histochemistry involving micro-assay of the ChAT activity of contiguous microdissected samples. Both methods indicate prominent ChAT activity in the basolateral amygdaloid nucleus (especially rostrally), the nucleus of the lateral olfactory tract (especially layer II), and the amygdalohippocampal area. Regions of lower ChAT activity were not accurately represented by the immunohistochemistry, but could be discriminated by the quantitative assays. Lowest activity was found in the medial nucleus of the amygdala. Most other regions had activities at least as high as average brain or neocortex. Gradients of enzyme activity were found within several regions, including the basolateral and lateral amygdaloid nuclei and the nearby posterior piriform cortex. In the piriform cortex, a region of particularly high ChAT activity was found at its medial edge near the nucleus of the lateral olfactory tract. The immunohistochemical method shows a few intensely reactive somata in layer III within this zone. Comparison of the results seen with immunohistochemistry and quantitative histochemistry suggests an advantage in using them together, since their respective strengths and weaknesses tend to complement each other.