Endogenous TNF alpha orchestrates the trafficking of neutrophils into and within lymphatic vessels during acute inflammation

This work was supported by funds from Arthritis Research UK (19913 to M.-B.V.) and the Wellcome Trust (098291/Z/12/Z to S.N.). S. A. was supported by a QMUL Principal’s Award PhD Studentship

Genome-wide transcriptional profiling of peripheral blood leukocytes from cattle infected with Mycobacterium bovis reveals suppression of host immune genes

Background Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB), a pathological infection with significant economic impact. Recent studies have highlighted the role of functional genomics to better understand the molecular mechanisms governing the host immune response to M. bovis infection. Furthermore, these studies may enable the identification of novel transcriptional markers of BTB that can augment current diagnostic tests and surveillance programmes. In the present study, we have analysed the transcriptome of peripheral blood leukocytes (PBL) from eight M. bovis-infected and eight control non-infected age-matched and sex-matched Holstein-Friesian cattle using the Affymetrix® GeneChip® Bovine Genome Array with 24,072 gene probe sets representing more than 23,000 gene transcripts. Results Control and infected animals had similar mean white blood cell counts. However, the mean number of lymphocytes was significantly increased in the infected group relative to the control group (P = 0.001), while the mean number of monocytes was significantly decreased in the BTB group (P = 0.002). Hierarchical clustering analysis using gene expression data from all 5,388 detectable mRNA transcripts unambiguously partitioned the animals according to their disease status. In total, 2,960 gene transcripts were differentially expressed (DE) between the infected and control animal groups (adjusted P-value threshold ≤ 0.05); with the number of gene transcripts showing decreased relative expression (1,563) exceeding those displaying increased relative expression (1,397). Systems analysis using the Ingenuity® Systems Pathway Analysis (IPA) Knowledge Base revealed an over-representation of DE genes involved in the immune response functional category. More specifically, 64.5% of genes in the affects immune response subcategory displayed decreased relative expression levels in the infected animals compared to the control group. Conclusions This study demonstrates that genome-wide transcriptional profiling of PBL can distinguish active M. bovis-infected animals from control non-infected animals. Furthermore, the results obtained support previous investigations demonstrating that mycobacterial infection is associated with host transcriptional suppression. These data support the use of transcriptomic technologies to enable the identification of robust, reliable transcriptional markers of active M. bovis infection.This work was supported by Investigator Grants from Science Foundation Ireland (Nos: SFI/01/F.1/B028 and SFI/08/IN.1/B2038), a Research Stimulus Grant from the Department of Agriculture, Fisheries and Food (No: RSF 06 405) and a European Union Framework 7 Project Grant (No: KBBE-211602-MACROSYS). KEK is supported by the Irish Research Council for Science, Engineering and Technology (IRCSET) funded Bioinformatics and Systems Biology PhD Programme http://bioinfo-casl.ucd.ie/PhD

The role of the tissue microenvironment in the regulation of cancer cell motility and invasion

During malignant neoplastic progression the cells undergo genetic and epigenetic cancer-specific alterations that finally lead to a loss of tissue homeostasis and restructuring of the microenvironment. The invasion of cancer cells through connective tissue is a crucial prerequisite for metastasis formation. Although cell invasion is foremost a mechanical process, cancer research has focused largely on gene regulation and signaling that underlie uncontrolled cell growth. More recently, the genes and signals involved in the invasion and transendothelial migration of cancer cells, such as the role of adhesion molecules and matrix degrading enzymes, have become the focus of research. In this review we discuss how the structural and biomechanical properties of extracellular matrix and surrounding cells such as endothelial cells influence cancer cell motility and invasion. We conclude that the microenvironment is a critical determinant of the migration strategy and the efficiency of cancer cell invasion

Pathogen Specific, IRF3-Dependent Signaling and Innate Resistance to Human Kidney Infection

The mucosal immune system identifies and fights invading pathogens, while allowing non-pathogenic organisms to persist. Mechanisms of pathogen/non-pathogen discrimination are poorly understood, as is the contribution of human genetic variation in disease susceptibility. We describe here a new, IRF3-dependent signaling pathway that is critical for distinguishing pathogens from normal flora at the mucosal barrier. Following uropathogenic E. coli infection, Irf3−/− mice showed a pathogen-specific increase in acute mortality, bacterial burden, abscess formation and renal damage compared to wild type mice. TLR4 signaling was initiated after ceramide release from glycosphingolipid receptors, through TRAM, CREB, Fos and Jun phosphorylation and p38 MAPK-dependent mechanisms, resulting in nuclear translocation of IRF3 and activation of IRF3/IFNβ-dependent antibacterial effector mechanisms. This TLR4/IRF3 pathway of pathogen discrimination was activated by ceramide and by P-fimbriated E. coli, which use ceramide-anchored glycosphingolipid receptors. Relevance of this pathway for human disease was supported by polymorphic IRF3 promoter sequences, differing between children with severe, symptomatic kidney infection and children who were asymptomatic bacterial carriers. IRF3 promoter activity was reduced by the disease-associated genotype, consistent with the pathology in Irf3−/− mice. Host susceptibility to common infections like UTI may thus be strongly influenced by single gene modifications affecting the innate immune response

Leukocyte trafficking between stromal compartments: lessons from rheumatoid arthritis

The trafficking of leukocytes from their site of production in the bone marrow through the circulation and into peripheral tissues is a highly coordinated and tightly regulated process in healthy individuals. Lymphocytes are long-lived cells that visit many lymphoid and peripheral tissues over their lifetime and can even recirculate back to the bone marrow, whereas granulocytes and monocytes are not thought to recirculate so widely. Using rheumatoid arthritis (RA) as an example, this Review explores the migratory journey of leukocytes during the establishment and resolution of disease — from the blood, through the lymphoid tissues and into peripheral sites such as the lungs and the gut before their entry into the synovium. This Review explores our current understanding of differences in the molecular processes that regulate leukocyte trafficking at different phases of disease and in different stromal compartments, which could help to explain the disease heterogeneity seen in patients with RA. Expanding our knowledge of these processes will open new avenues in the clinical management of RA, paving the way for personalized medicine that is founded on the pathological molecular signature of each patient, which varies according to their phase of disease or disease subtype

Targeting ß2 adrenergic receptors regulate human T cell function directly and indirectly

It is well-established that central nervous system activation affects peripheral blood mononuclear cell (PBMCs) function through the release of the catecholamines (Epi) and norepinephrine (NE), which act on ß2-adrenergic receptors (ß2AR). However, most studies have used non-specific stimulation of cells rather than antigen-specific responses. Likewise, few studies have parsed out the direct effects of ß2AR stimulation on T cells versus indirect effects via adrenergic stimulation of antigen presenting cells (APC). Here we report the effect of salmeterol (Sal), a selective ß2AR agonist, on IFN-γ+ CD4 and IFN-γ+ CD8 T cells following stimulation with Cytomegalovirus lysate (CMVL-strain AD169) or individual peptides spanning the entire region of the HCMV pp65 protein (pp65). Cells were also stimulated with Staphylococcal enterotoxin B. Additionally, we investigated the effect of Epi and Sal on cytotoxic cell killing of transfected target cells at the single cell level using the CD107a assay. The results show that Sal reduced the percentage of IFN-γ+ CD4 and IFN-γ+ CD8 T cells both when applied directly to isolated T cells, and indirectly via treatment of APC. These inhibitory effects were mediated via a ß2 adrenergic-dependent pathway and were stronger for CD8 as compared to CD4 T cells. Similarly, the results show that Sal suppressed cytotoxicity of both CD8 T and NK cells in vitro following stimulation with Chinese hamster ovary cell line transfected with MICA*009 (T-CHO) and the human erythromyeloblastoid leukemic (K562) cell line. The inhibitory effect on cytotoxicity following stimulation with T-CHO was stronger in NK cells compared with CD8 T cells. Thus, targeting the ß2AR on lymphocytes and on APC leads to inhibition of inflammatory cytokine production and target cell killing. Moreover, there is a hierarchy of responses, with CD8 T cells and NK cells inhibited more effectively than CD4 T cells

A differential role for CD248 (Endosialin) in PDGF-mediated skeletal muscle angiogenesis

CD248 (Endosialin) is a type 1 membrane protein involved in developmental and pathological angiogenesis through its expression on pericytes and regulation of PDGFRβ signalling. Here we explore the function of CD248 in skeletal muscle angiogenesis. Two distinct forms of capillary growth (splitting and sprouting) can be induced separately by increasing microcirculatory shear stress (chronic vasodilator treatment) or by inducing functional overload (extirpation of a synergistic muscle). We show that CD248 is present on pericytes in muscle and that CD248-/-mice have a specific defect in capillary sprouting. In contrast, splitting angiogenesis is independent of CD248 expression. Endothelial cells respond to prosprouting angiogenic stimulus by up-regulating gene expression for HIF1α, angiopoietin 2 and its receptor TEK, PDGF-B and its receptor PDGFR beta; this response did not occur following a pro-splitting angiogenic stimulus. In wildtype mice, defective sprouting angiogenesis could be mimicked by blocking PDGFR beta; signalling using the tyrosine kinase inhibitor Imatinib mesylate. We conclude that CD248 is required for PDGFR beta;-dependant capillary sprouting but not splitting angiogenesis, and identify a new role for CD248 expressed on pericytes in the early stages of physiological angiogenesis during muscle remodelling