Biomedical subjects

Amy Rasley

Publications and source records attributed to Amy Rasley.

8 recordsLinked to original sources

PubMed2006

Array2BIO: from microarray expression data to functional annotation of co-regulated genes.

BACKGROUND: There are several isolated tools for partial analysis of microarray expression data. To provide an integrative, easy-to-use and automated toolkit for the analysis of Affymetrix microarray expression data we have developed Array2BIO, an application that couples several analytical methods into a single web based utility. RESULTS: Array2BIO converts raw intensities into probe expression values, automatically maps those to genes, and subsequently identifies groups of co-expressed genes using two complementary approaches: (1) comparative analysis of signal versus control and (2) clustering analysis of gene expression across different conditions. The identified genes are assigned to functional categories based on Gene Ontology classification and KEGG protein interaction pathways. Array2BIO reliably handles low-expressor genes and provides a set of statistical methods for quantifying expression levels, including Benjamini-Hochberg and Bonferroni multiple testing corrections. An automated interface with the ECR Browser provides evolutionary conservation analysis for the identified gene loci while the interconnection with Crème allows prediction of gene regulatory elements that underlie observed expression patterns. CONCLUSION: We have developed Array2BIO - a web based tool for rapid comprehensive analysis of Affymetrix microarray expression data, which also allows users to link expression data to Dcode.org comparative genomics tools and integrates a system for translating co-expression data into mechanisms of gene co-regulation. Array2BIO is publicly available at http://array2bio.dcode.org.

Algorithms↗

PubMed2006

Murine glia express the immunosuppressive cytokine, interleukin-10, following exposure to Borrelia burgdorferi or Neisseria meningitidis.

There is growing appreciation that resident glial cells can initiate and/or regulate inflammation following trauma or infection in the central nervous system (CNS). We have previously demonstrated the ability of microglia and astrocytes, resident glial cells of the CNS, to respond to bacterial pathogens by rapid production of inflammatory mediators. However, inflammation within the brain parenchyma is notably absent during some chronic bacterial infections in humans and nonhuman primates. In the present study, we demonstrate the ability of the immunosuppressive cytokine, interleukin-10 (IL-10), to inhibit inflammatory immune responses of primary microglia and astrocytes to B. burgdorferi and N. meningitidis, two disparate gram negative bacterial species that can cross the blood-brain barrier in humans. Importantly, we demonstrate that these organisms induce the delayed production of significant quantities of IL-10 by both microglia and astrocytes. Furthermore, we demonstrate that such production occurs independent of the actions of bacterial lipopolysaccharide and is secondary to the autocrine or paracrine actions of other glia-derived soluble mediators. The late onset of IL-10 production by resident glia following activation, the previously documented expression of specific receptors for this cytokine on microglia and astrocytes, and the ability of IL-10 to inhibit bacterially induced immune responses by these cells, suggest a mechanism by which resident glial cells can limit potentially damaging inflammation within the CNS in response to invading pathogens, and could explain the suppression of inflammation seen within the brain parenchyma during chronic bacterial infections.

Animals↗

PubMed2004

Substance P augments Borrelia burgdorferi-induced prostaglandin E2 production by murine microglia.

Substance P is a ubiquitous CNS neuropeptide and has recently been demonstrated to augment immune cell function during inflammatory events. Central to the ability of substance P to modulate immune cell function is the interaction of substance P with the substance P neurokinin-1 receptor expressed by a variety of immune cells, including microglia. CNS involvement during Lyme disease can occur when Borrelia burgdorferi, the causative agent of Lyme disease, gains access to the CNS. In the present study, we demonstrate that substance P augments B. burgdorferi-induced expression of mRNA encoding COX-2 and subsequent secretion of PGE(2) by cultured, murine microglia. Furthermore, this effect is associated with the ability of substance P to enhance B. burgdorferi-induced NF-kappa B activation, as demonstrated by increased nuclear localization of the p65 (RelA) subunit of NF-kappa B in these cells. Interestingly, we demonstrate that substance P augments B. burgdorferi-induced expression of mRNA encoding two PGE(2) receptors, E-prostanoid receptor subtypes 2 and 4, as well as each receptor protein. In addition, these effects are mediated via interactions between substance P and its high affinity receptor, as evidenced by the absence of augmented PGE(2) synthesis in the presence of a specific neurokinin-1 receptor antagonist or in cells genetically deficient in the expression of these receptors. Taken together, the present demonstration that substance P can exacerbate B. burgdorferi-induced inflammatory responses in microglia in vitro may indicate a role for this neuropeptide in the development of CNS inflammation observed during human neuroborreliosis.

Adjuvants, Immunologic↗

PubMed2004

Murine gammaherpesvirus-68 elicits robust levels of interleukin-12 p40, but not interleukin-12 p70 production, by murine microglia and astrocytes.

Murine gammaherpesvirus-68 (gamma HV-68) is a tractable model to investigate the pathophysiology of human gammaherpesvirus infections, including Epstein-Barr virus (EBV). Herpesvirus infections are thought to play a role in the pathology of damaging, inflammatory diseases states of the central nervous system (CNS), such as multiple sclerosis. The ability of the host to mount a strong cell-mediated immune response is critical in determining the outcome of viral infections. Interleukin (IL)-12 is an important inflammatory cytokine that plays a pivotal role in the development of protective cell-mediated immune responses to viral infections. Given recent reports of associations between gammaherpesvirus infections and inflammatory disorders of the CNS, the authors investigated the ability of gamma HV-68 to induce the production of bioactive IL-12 in resident CNS cell types. In the present study, the authors demonstrate that gamma HV-68 infection is a potent stimulus for IL-12p40 production by murine microglia and astrocytes. However, despite the elevated expression of mRNA encoding IL-12p40 subunit, concomitant with robust secretion of IL-12p40 protein, gamma HV-68 failed to elicit the production of the bioactive IL-12p70 heterodimer. This failure did not result from an absence of T lymphocyte-derived signals or interactions between CNS cell types as determined by coculture studies. Taken together, these data suggest that the resident CNS cell types, astrocytes and microglia, are not significant sources of proinflammatory IL-12p70 in response to gammaherpesvirus infection. Indeed, the production of IL-12p40 may point to an anti-inflammatory role for these cells during herpesvirus infections of the CNS.

Animals↗

PubMed2003

Cultured astrocytes express toll-like receptors for bacterial products.

It has become apparent that astrocytes may be important contributors to inflammatory immune responses within the brain in response to microbial challenges. To date, the mechanisms that underlie activation of this major glial cell type by such challenges have not been investigated. In the present study, we present evidence for members of a recently discovered family of receptors for highly conserved microbial components, the Toll-like receptors (TLRs), in isolated cultures of primary murine astrocytes. We describe the low-level constitutive expression of messenger RNA-encoding TLR2, TLR4, TLR5, and TLR9 in resting cultures of these cells. Importantly, the level of expression of messenger RNA for each of these receptors is markedly elevated following exposure to specific bacteria-derived ligands for these receptors. The functional expression of these receptor proteins is further supported by the ability of known ligands for each TLR to induce both message expression and protein secretion of the proinflammatory cytokine, interleukin-6. In addition, the recent availability of antibodies to TLR2 and TLR4 has enabled us to demonstrate directly the presence of these receptors on astrocytes by Western blot and immunofluorescence analysis, respectively. Furthermore, we have confirmed the sensitivity of such receptor expression to ligand stimulation. The present demonstration of Toll-like microbial pattern-recognition receptors on primary astrocytes provides a mechanistic link between bacterial challenge and inflammatory immune responses that may be an important component of the pathologies of bacterially induced inflammatory CNS disorders.

Animals↗

PubMed2003

Murine gammaherpesvirus-68 infects microglia and induces high levels of pro-inflammatory cytokine production.

Murine gammaherpesvirus-68 (MHV-68) has been established as a tractable model for the study of human herpesvirus infections. Recent associations between herpesvirus infections and inflammatory central nervous system (CNS) disorders, including multiple sclerosis (MS), have prompted us to investigate the susceptibility of cultured microglia and astrocytes to MHV-68 infection. In the present study, we demonstrate that MHV-68 can infect both cell types. Importantly, we show that MHV-68-infected microglia and astrocytes can produce pro-inflammatory cytokines. Such cytokine production may either contribute to protective host responses to viral challenges or could exacerbate damaging CNS inflammation.

Animals↗

PubMed2002

Expression of functional NK-1 receptors in murine microglia.

Cells of myeloid origin such as microglia have the potential to contribute significantly to the development of inflammatory responses in the CNS. The ability of the neuropeptide substance P to augment proinflammatory responses by other myeloid cell types such as macrophages and dendritic cells is well recognized. In the present study, we demonstrate the presence of mRNA encoding NK-1 (substance P) receptors in murine microglia cell lines. Importantly, we have utilized specific antibodies developed by our laboratory to detect the expression of the NK-1 receptor protein in murine microglia cell lines by Western blot analysis and flow cytometry. Furthermore, we have investigated the presence of this receptor on primary murine microglia and report the presence of authentic NK-1 receptors as determined by Western blot analysis and flow cytometry. In addition, we demonstrate that NK-1 receptors expressed on microglia are functional as demonstrated by the ability of nanomolar concentrations of substance P to initiate activation of the transcriptional activator, NF-kappaB. Given the weight of evidence supporting the role of substance P--substance P receptor interactions in the initiation of optimal proinflammatory responses by myeloid cells, the demonstration of authentic and functional NK-1 receptors in microglia identifies this neuropeptide as a potentially important contributor to CNS inflammatory responses during disease states.

Animals↗

PubMed2002

Borrelia burgdorferi induces inflammatory mediator production by murine microglia.

Lyme disease has been associated with damaging inflammation within the central nervous system. In the present study, we demonstrate that Borrelia burgdorferi is a significant stimulus for the production of IL-6, TNF-alpha, and PGE(2) by microglia. This effect is associated with induction of NF-kappaB, and increased expression of Toll-like receptor 2 and CD14, receptors known to underlie spirochete activation of other immune cell types. These studies identify microglia as a previously unappreciated source of inflammatory mediator production following challenge with B. burgdorferi. Such production may play an important role during the development of Lyme neuroborreliosis.

Animals↗