Chemotactic activity of extracellular nucleotideson human immune cells.

Purinergic P2 receptors are a class of plasma membrane receptors that are express in many tissues and are ligated by extracellular nucleotides [such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), uridine 5–triphosphate (UTP) and uridine 5–diphosphate (UDP)], which are released as a consequence of cell damage, cell stress, bacterial infection or other noxious stimuli. According to the molecular structure, P2 receptors are divided into two subfamilies: P2X and P2Y receptors. The P2X receptors are ligand-gated channels, whereas P2Y receptors are G-protein-coupled seven-membrane-spanning receptors. Several studies indicate that nucleotides play an important role in immune response modulation through their action on multiple cell types, including monocytes, mast cells, dendritic cells, neutrophils, and eosinophils. Recent work by our group and others identified extracellular nucleotides as chemotaxins for various human immune cells, including eosinophils, neutrophils and dendritic cells. In this review, we summarise recent findings in this field and put forward a hypothesis on the role of P2 receptors in the early recruitment of human immune cells to the site of inflammation

Peripheral Nervous System Genes Expressed in Central Neurons Induce Growth on Inhibitory Substrates

Trauma to the spinal cord and brain can result in irreparable loss of function. This failure of recovery is in part due to inhibition of axon regeneration by myelin and chondroitin sulfate proteoglycans (CSPGs). Peripheral nervous system (PNS) neurons exhibit increased regenerative ability compared to central nervous system neurons, even in the presence of inhibitory environments. Previously, we identified over a thousand genes differentially expressed in PNS neurons relative to CNS neurons. These genes represent intrinsic differences that may account for the PNS’s enhanced regenerative ability. Cerebellar neurons were transfected with cDNAs for each of these PNS genes to assess their ability to enhance neurite growth on inhibitory (CSPG) or permissive (laminin) substrates. Using high content analysis, we evaluated the phenotypic profile of each neuron to extract meaningful data for over 1100 genes. Several known growth associated proteins potentiated neurite growth on laminin. Most interestingly, novel genes were identified that promoted neurite growth on CSPGs (GPX3, EIF2B5, RBMX). Bioinformatic approaches also uncovered a number of novel gene families that altered neurite growth of CNS neurons

Nucleotide receptor signalling and the generation of reactive oxygen species

Elevated levels of extracellular nucleotides are present at sites of inflammation, platelet degranulation and cellular damage or lysis. These extracellular nucleotides can lead to the activation of purinergic (nucleotide) receptors on various leukocytes, including monocytes, macrophages, eosinophils, and neutrophils. In turn, nucleotide receptor activation has been linked to increased cellular production and release of multiple inflammatory mediators, including superoxide anion, nitric oxide and other reactive oxygen species (ROS). In the present review, we will summarize the evidence that extracellular nucleotides can facilitate the generation of multiple ROS by leukocytes. In addition, we will discuss several potential mechanisms by which nucleotide-enhanced ROS production may occur. Delineation of these mechanisms is important for understanding the processes associated with nucleotide-induced antimicrobial activities, cell signalling, apoptosis, and pathology

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells

A randomized, open-label, multicentre, phase 2/3 study to evaluate the safety and efficacy of lumiliximab in combination with fludarabine, cyclophosphamide and rituximab versus fludarabine, cyclophosphamide and rituximab alone in subjects with relapsed chronic lymphocytic leukaemia

Lumiliximab is a chimeric monoclonal antibody that targets CD23 on the surface of chronic lymphocytic leukaemia (CLL) B-cells. Early phase clinical studies with lumiliximab alone and in combination with fludarabine, cyclophosphamide and rituximab (FCR) established its potential efficacy and tolerability. The 152CL201 trial [Lumiliximab with fludarabine, cyclophosphamide and rituximab (FCR) versus FCR alone in subjects with relapsed CLL; LUCID] was a phase 2/3, randomized (1:1), open-label, multicentre study of lumiliximab in combination with FCR versus FCR alone in patients with relapsed CLL. Six hundred and twenty-seven patients were randomized to either arm. Overall the combination of lumiliximab with FCR was not significantly better than FCR alone (overall response rate 71% vs. 72%, complete response rate 16% vs. 15%, median progression-free survival 24.6 vs. 23.9 months respectively, for FCR with and without lumiliximab). There was a slightly increased incidence of adverse events with lumiliximab but these increases did not appear to lead to differences in eventual outcomes. An interim analysis failed to show sufficient efficacy of the combination of lumiliximab with FCR. The study was therefore stopped early for lack of efficacy. Despite the eventual outcome, the LUCID trial is one of the largest studies that provides valuable insight into the efficacy and tolerability of FCR as a therapeutic option for patients with relapsed CLL

A randomized, open-label, multicentre, phase 2/3 study to evaluate the safety and efficacy of lumiliximab in combination with fludarabine, cyclophosphamide and rituximab versus fludarabine, cyclophosphamide and rituximab alone in subjects with relapsed chronic lymphocytic leukaemia.

Lumiliximab is a chimeric monoclonal antibody that targets CD23 on the surface of chronic lymphocytic leukaemia (CLL) B-cells. Early phase clinical studies with lumiliximab alone and in combination with fludarabine, cyclophosphamide and rituximab (FCR) established its potential efficacy and tolerability. The 152CL201 trial [Lumiliximab with fludarabine, cyclophosphamide and rituximab (FCR) versus FCR alone in subjects with relapsed CLL; LUCID] was a phase 2/3, randomized (1:1), open-label, multicentre study of lumiliximab in combination with FCR versus FCR alone in patients with relapsed CLL. Six hundred and twenty-seven patients were randomized to either arm. Overall the combination of lumiliximab with FCR was not significantly better than FCR alone (overall response rate 71% vs. 72%, complete response rate 16% vs. 15%, median progression-free survival 24.6 vs. 23.9 months respectively, for FCR with and without lumiliximab). There was a slightly increased incidence of adverse events with lumiliximab but these increases did not appear to lead to differences in eventual outcomes. An interim analysis failed to show sufficient efficacy of the combination of lumiliximab with FCR. The study was therefore stopped early for lack of efficacy. Despite the eventual outcome, the LUCID trial is one of the largest studies that provides valuable insight into the efficacy and tolerability of FCR as a therapeutic option for patients with relapsed CLL