CD4+ T Cell Effects on CD8+ T Cell Location Defined Using Bioluminescence

T lymphocytes of the CD8+ class are critical in delivering cytotoxic function and in controlling viral and intracellular infections. These cells are “helped” by T lymphocytes of the CD4+ class, which facilitate their activation, clonal expansion, full differentiation and the persistence of memory. In this study we investigated the impact of CD4+ T cells on the location of CD8+ T cells, using antibody-mediated CD4+ T cell depletion and imaging the antigen-driven redistribution of bioluminescent CD8+ T cells in living mice. We documented that CD4+ T cells influence the biodistribution of CD8+ T cells, favoring their localization to abdominal lymph nodes. Flow cytometric analysis revealed that this was associated with an increase in the expression of specific integrins. The presence of CD4+ T cells at the time of initial CD8+ T cell activation also influences their biodistribution in the memory phase. Based on these results, we propose the model that one of the functions of CD4+ T cell “help” is to program the homing potential of CD8+ T cells

Correlation Of Ultrasound-Induced Hemolysis With Cavitation Detector Output In Vitro

A 20-MHz passive acoustic detector was used to quantify the amount of transient acoustic cavitation occurring in a sample exposed to intense pulsed ultrasound, A dilute suspension of human erythrocytes with and without a microbubble echo-contrast agent was exposed in vitro to 500 W/cm(2) (SPPA) ultrasound of center frequency 1 MHz and tone burst duration 20, 100, 200, 500 and 1000 mu s at a pulse repetition frequency of 20 Hz. Inertial cavitation occurring within the sample, as measured by the temporal average of the detector output, correlated well with hemolysis, suggesting that violent bubble collapse is responsible for cell damage, The result also raises the prospect of cavitation monitoring as a possible predictor of adverse bioeffects when echo-contrast agents are used clinically. (C) 1997 World Federation for Ultrasound in Medicine & Biology

Bone Marrow Mesenchymal Stem Cells from Acute Myelogenous Leukemia Patients Demonstrate Adipogenic Differentiation Propensity

Abstract Background: Bone marrow mesenchymal stem cells (BMSCs) constitute one of the important cellular components of the hematopoietic microenvironmental niche. These cells are capable of differentiation into osteoprogenitors which comprise part of the endosteal niche. In vivo studies have shown that depletion of BMSCs resulted in reduction of hematopoietic stem cell content, and there is direct in vitro evidence that BMSCs are able to support both normal and leukemia progenitor cell proliferation and survival and contribute to leukemia cell resistance to cytotoxic therapies. Whether BMSCs from leukemia marrow differ from normal counterparts and how they contribute to and are influenced by the leukemia environmental niche are still incompletely understood. In this work we sought to compare normal and AML-derived BMSCs and to define the propensity of BMSCs from leukemia patients for osteogenic or adipogenic differentiation. Methods: BMSCs were isolated from marrow aspirates of normal donor and AML patients using standard methodologies. Donors were age-matched to the leukemia patients to the extent possible in each comparative experiment. Such cells met the definition of MSCs in that they were adherent and expressed CD73, CD90, CD44, CD117 and CD105 and had osteoblastic and adipogenic differentiation capabilities. All comparisons were done at comparable passage number between samples. Results: BMSCs from AML donors demonstrated irregular vs. spindle shaped morphology as compared with BMSCs from younger donors &lt;50 years of age but similar morphology to those grown from older donors. AML derived BMSCs were larger and had slower growth rate as assessed by longer passage times during lower passages (41 vs. 21 days). Cell surface expression markers were similar between normal and AML. CFU-F outgrowth was less from AML as compared to normal BMSC, and no difference in osteogenic differentiation was noted by Alizarin Red S measurement. On the other hand, lipid droplet formation measured by Oil Red O during adipogenic differentiation induction was greater in the AML BMSCs as compared with age matched controls, suggesting increased adipogenic differentiation potential. To determine if we could detect a gene signature difference between AML and normal BMSCs which would predict adipogenic propensity, RNA-Seq analysis was performed on AML and normal donor specimens(n=3 in each group), all from subjects &gt;50 years of age using CuffDiff (v2.0.2). This identified 88 genes differentially expressed between the two groups. A heat map was generated using Euclidean distance hierarchical clustering of gene expression values from individual samples. This readily grouped AML vs. normal samples. Pathway analysis using Ingenuity Pathway Analysis (IPA) predicted dysregulation of four canonical pathways in AML-BMSCs as compared to normal BMSCs. These included 1) Role of tissue factor in cancer, 2) Airway pathology in COPD, 3) Oleate biosynthesis, and 4) Adipogenesis. The last two pathways are consistent with the biological observation of enhanced adipogenesis in AML-derived BMSCs. IPA analysis proposed a model of altered adipogenic differentiation in AML-BMSCs attributable to lower expression of two key regulatory genes, SOX9 and EGR2. Reduced expression of SOX9 and EGR2 in AML BMSCs as compared to normal BMSCs was validated by qRT-PCR and western blot analysis. SOX9 is reported to contribute to the commitment of MSCs to adipogenic phenotype through negative influence on expression of key transcription factors in adipogenesis, and ERG2 downregulation is required in some systems for adipocyte lineage commitment. Conclusion: Understanding the role that adipogenic MSCs play during leukemia evolution and treatment could offer insight into pathogenesis and potential therapies for these disorders. Disclosures Liesveld: Onconova: Other: Data safety monitoring board; Astex: Honoraria; glycomimetics: Research Funding. </jats:sec

Nitrogen dioxide exposure: effects on airway and blood cells

This study examined the effects of nitrogen dioxide (NO2) exposure on airway inflammation, blood cells, and antiviral respiratory defense. Twenty-one healthy volunteers were exposed on separate occasions to air and 0.6 and 1.5 ppm NO2for 3 h with intermittent moderate exercise. Phlebotomy and bronchoscopy were performed 3.5 h after each exposure, and recovered cells were challenged with respiratory viruses in vitro. Blood studies revealed a 4.1% NO2dose-related decrease in hematocrit ( P = 0.003). Circulating total lymphocytes ( P = 0.024) and T lymphocytes ( P = 0.049) decreased with NO2exposure. Exposure to NO2increased the blood lymphocyte CD4+-to-CD8+ratio from 1.74 ± 0.11 to 1.85 ± 0.12 in males but decreased it from 1.88 ± 0.19 to 1.78 ± 0.19 in females ( P &lt; 0.001 for gender difference). Polymorphonuclear leukocytes in bronchial lavage increased with NO2exposure ( P = 0.003). Bronchial epithelial cells obtained after exposure to 1.5 ppm NO2released 40% more lactate dehydrogenase after challenge with respiratory syncytial virus than with air exposure ( P = 0.024). In healthy subjects, exposures to NO2at levels found indoors cause mild airway inflammation, effects on blood cells, and increased susceptibility of airway epithelial cells to injury from respiratory viruses.</jats:p

Follicular Lymphoma Tregs Have a Distinct Transcription Profile Impacting Their Migration and Retention in the Malignant Lymph Node

<div><p>We have previously shown that regulatory T cells (Tregs) infiltrating follicular lymphoma lymph nodes are quantitatively and qualitatively different than those infiltrating normal and reactive nodes. To gain insight into how such Treg populations differ, we performed RNA sequence (RNAseq) analyses on flow sorted Tregs from all three sources. We identify several molecules that could contribute to the observed increased suppressive capacity of follicular lymphoma nodal tregs, including upregulation of CTLA-4, IL-10, and GITR, all confirmed by protein expression. In addition, we identify, and confirm functionally, a novel mechanism by which Tregs target to and accumulate within a human tumor microenvironment, through the down regulation of S1PR1, SELL (L-selectin) and CCR7, potentially resulting in greater lymph node retention. In addition we identify and confirm functionally the upregulation of the chemokine receptor CXCR5 as well as the secretion of the chemokines CXCL13 and IL-16 demonstrating the unique ability of the follicular derived Tregs to localize and accumulate within not only the malignant lymph node, but also localize and accumulate within the malignant B cell follicle itself. Such findings offer significant new insights into how follicular lymphoma nodal Tregs may contribute to the biology of follicular lymphoma and identify several novel therapeutic targets.</p></div

Gene expression scatter plots of selected genes by category.

RPM data are not log-transformed for these plots. Line segments are group means. A. Treg subset genes. B. Treg homing and retention genes. C. Immune cell recruitment genes.</p