Reconstitution of a functional interleukin (IL)-7 receptor demonstrates that the IL-2 receptor γ chain is required for IL-7 signal transduction

The interleukin (IL)-2 receptor γ chain has recently been shown to be a component of the IL-7 and IL-4 receptors. Using a transient transfection assay and the trans-activation of reporter gene constructs which are under the control of cytokine-responsive promoter elements, we have studied signal transduction through the IL-7 receptor (IL-7R). The reporter gene expression was not stimulated by receptors that contained the cytoplasmic domain of the IL-7R, either as intact IL-7R or as part of a chimeric receptor. However, co-expression of the IL-7R with the IL-2 receptor γ chain was able to stimulate gene activation. For maximal stimulation the intact cytoplasmic domains of each chain was required.     

A B7-1-transfected human melanoma line stimulates proliferation and cytotoxicity of autologous and allogeneic lymphocytes

B7 co-stimulation is necessary to activate resting T cells upon antigen recognition by the T cell receptor. To see whether expression of B7 may render human melanoma cells able to stimulate T cells, a cloned melanoma line (Me1B6), which did not express B7-1, was transfected with the human B7-1 gene. In proliferation assays, B7-1 transfected cells (Me1B6/B7) showed greater stimulatory activity of allogeneic and autologous peripheral blood lymphocytes (PBL) compared to parental, non-transfected tumor cells. This effect was also seen when allogeneic CD8⁺ and CD4⁺ subpopulations were used as effectors. In these studies, activation of lymphocytes was B7-1-dependent and HLA classes I and II mediated. The higher proliferation correlated with an increased lytic activity by PBL stimulated with B7-1⁺ tumor cells against the untransfected Me1B6. Furthermore, PBL from a metastatic melanoma patient stimulated by Me1B6/B7 developed an higher lytic activity not only against Me1B6 but also against their autologous, B7-1^? tumor. Finally, after Me1B6/B7 stimulation, PBL released interleukin (IL)-2 and interferon-γ, but not IL-4, suggesting a Th1-mediated response. These data support the use of B7-1 transfected melanoma cells in the therapeutic vaccination of melanoma patients.     

Morphine-6beta-glucuronide modulates the expression of inducible nitric oxide synthase

The immunomodulatory effects of morphine are well established; however, suprisingly little is known about the immunomodulatory properties of the major metabolites of morphine. The present study tests the hypothesis that expression of inducible nitric oxide synthase (iNOS) is modulated by the administration of the morphine metabolite, morphine-6-glucuronide. The initial study using rats shows that morphine-6-glucuronide administration (0, 1.0, 3.163, 10 mg/kg s.c.) results in a pronounced reduction in lipopolysaccharide (LPS)-induced expression of iNOS (inducible nitricoxide synthease) in spleen, lung, and liver tissue as measured by western blotting. Morphine-6-glucuronide also produces a reduction in the level of plasma nitrite/nitrate, the more stable end-product of nitric oxide degradation. In a subsequent study, administration of the opioid receptor antagonist, naltrexone (0.1 mg/kg) prior to the injection of morphine-6-glucuronide (10 mg/kg) blocks the morphine-6-glucuronide induced reduction of iNOS expression and plasma nitrite/nitrite levels indicating that the effect is mediated via the opioid-receptor. This study provides the first evidence that morphine-6-glucuronide alters the expression of iNOS.     

ABC proteins: key molecules for lipid homeostasis

Forty-nine ABC protein genes exist on human chromosomes. Eukaryotic ABC proteins were originally recognized as drug efflux pumps involved in the multidrug resistance of cancer cells. However, it is now realized that one of their major physiological roles is cellular lipid transport and homeostasis, and their dysfunction is often associated with human diseases. ABCA1 and ABCA7 mediate the apolipoprotein-dependent formation of a high-density lipoprotein–cholesterol complex. ABCA3 is indispensable for pulmonary surfactant secretion. ABCG5 and ABCG8 are involved in the secretion of plant sterols and cholesterol into bile. However, the primary substrates and mechanism of action of these ABC proteins have not been precisely defined. In this review article, we first describe the general structure and functions of eukaryotic ABC proteins. The current model of ABCA1 functionality is then explained based on studies on a topological model, subcellular localization, apoA-I dependence of HDL formation, functional defects of Tangier disease mutants, and ATP hydrolysis of purified ABCA1. ABCA1 is supposed to function as a transporter of lipids as well as a receptor for apoA-I. ABCA3 is likely involved in accumulating phospholipids and cholesterol in lamellar bodies and in generating multivesicular structures.     

Norrie disease caused by a gene deletion allowing carrier detection and prenatal diagnosis

Carrier determination and prenatal diagnosis in Norrie disease (ND) has so far not been reported. We describe a kindred with 4 members affected by ND in which a deletion comprising gene locus DXS7 on the short arm of the X chromosome defined by probe L1.28 causes the disorder. This allowed us to predict via chorion villus biopsy that a male foetus of a carrier woman is unaffected.     

Splice variants of the relaxin and INSL3 receptors reveal unanticipated molecular complexity

LGR7 and LGR8 are G protein-coupled receptors that belong to the leucine-rich repeat-containing G-protein coupled receptor (LGR) family, including the thyroid-stimulating hormone (TSH), LH and FSH receptors. LGR7 and LGR8 stimulate cAMP production upon binding of the cognate ligands, relaxin and insulin-like peptide 3 (INSL3), respectively. We cloned several novel splice variants of both LGR7 and LGR8 and analysed the function of four variants. LGR7.1 is a truncated receptor, including only the N-terminal region of the receptor and two leucine rich repeats. In contrast, LGR7.2, LGR7.10 and LGR 8.1 all contain an intact seven transmembrane domain and most of the extracellular region, lacking only one or two exons in the ectodomain. Our analysis demonstrates that although LGR7.10 and LGR8.1 are expressed at the cell surface, LGR7.2 is predominantly retained within cells and LGR7.1 is partially secreted. mRNA expression analysis revealed that several variants are co-expressed in various tissues. None of these variants were able to stimulate cAMP production following relaxin or INSL3 treatment. Unexpectedly, we did not detect any direct specific relaxin or INSL3 binding on any of the splice variants. The large number of receptor splice variants identified suggests an unforeseen complexity in the physiology of this novel hormone-receptor system.     

Cooperation between IL-7 and the pre-B cell receptor: a key to B cell selection

Hematopoiesis is regulated by a variety of signals that either originate within a developing cell or are supplied by the surrounding environment in secreted- or contact-dependent forms. This review discusses the effects of one secreted factor, interleukin-7, on the development of B lymphocytes. We describe a molecular mechanism for a crucial checkpoint during B lineage maturation, based on the integration of signals mediated by the pre-B cell receptor, the interleukin-7 receptor, and the environment in which these signals are received.     

Ex vivo stimulation of cord blood mononuclear cells by dexamethasone and interleukin-7 results in the maturation of interferon-gamma-secreting effector memory T cells

The effects of dexamethasone phosphate and interleukin‐7 upon the proliferation of T‐cells and the production of interferon‐γ in the newborn's cord blood mononuclear cell cultures were studied. The capability of dexamethasone to enhance T‐cell proliferation induced by anti‐CD3 with interleukin‐7 in some newborn cord blood mononuclear cell cultures was identified. Dexamethasone suppressed production of interferon‐γ in 68‐h cell cultures stimulated with anti‐CD3 both in the presence of interleukin‐7 and without it. However, a 68‐h cultivation of newborn blood cells with dexamethasone, anti‐CD3 and interleukin‐7 resulted in the accumulation of T‐lymphocytes capable of producing interferon‐γ after restimulation. As a result of it the amount of interferon‐γ producing CD7⁺ T‐cells and the concentration of interferon‐γ in cultural supernatants were maximal in the cell cultures incubated with anti‐CD3, interleukin‐7 and dexamethasone during the first 68 h and subsequently restimulated with phorbol 12‐myristate 13‐acetate and ionomycin. The stimulation of neonatal or adult blood cells by dexamethasone, anti‐CD3 and interleukine‐7 also causes a decrease in the number of naïve T‐cells and central memory cells and an increase in the number of effector memory CD7⁺CD45RA⁺CD62L^– cells in cultures. It is possible that these effects are caused by the influence of dexamethasone on IL‐7 receptor expression: it is known that IL‐7 receptor alpha‐chain gene is a glucocorticoid‐inducible gene.     

Effect of injury to the zone of the medial forebrain bundle and preoptic region on activity of an epileptiform focus induced by penicillin (on the phenomenon of the hyperactive determinant dispatch station)

Experiments on cats showed that injury to the medial forebrain bundle (MFB) and also partly to the preoptic region on the side of application of penicillin to the cerebral cortex (middle suprasylvian gyrus) causes depression of paroxysmal activity (spike potentials) in the penicillin focus, and also in a secondary mirror focus arising in the symmetrical zone of the opposite cortex. Injury to MFB on the side of the mirror focus causes depression of paroxysmal spike potentials only in that focus and does not affect activity in the primary epileptiform focus. The effects described are examined from the standpoint of views regarding the role of the determinant dispatch station (DDS) in the activity of the CNS: A primary epileptiform focus is a hyperactive DDS which induces the appearance of secondary foci, supports them, and determines the character of their activity. The results of the investigation suggests a role for MFB in the modulation of cortical epileptiform activity.Laboratory of General Pathology of the Nervous System, Institute of General Pathology and Pathophysiology, Academy of Medical Sciences of the USSR, Moscow. Laboratory of Electrophysiology, V. F. Filatov Odessa Research Institute for Eye Diseases and Tissue Therapy, Ministry of Health of the Ukrainian SSR. Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1413–1416, December, 1976.     

Interaction of B7RP-1 with ICOS Negatively Regulates Antigen Presentation by B Cells

Stimulation of T cells through the T cell receptor is insufficient for optimal T cell activation. A second activation signal is necessary, being usually provided by the costimulatory molecule CD28. Recently, additional costimulatory pathways have been identified, including inducible costimulator (ICOS) and its ligand B7RP-1. We have examined the role of the B7RP-1/ICOS costimulatory pathway on antigen presentation by B cells, using the I-A^k and I-E^k-positive CH27 B cell line and several different T cell lines. We found that CH27 expressed B7RP-1 and PD-L1 whereas the T cell lines expressed ICOS and PD-1. In the presence of HEL, the T cell hybridomas C10 and 3A9 released IL-2, which is indicative of antigen-specific T cell activation by the CH27 cells. Unexpectedly, blocking antibodies for B7RP-1 and ICOS enhanced the IL-2 response in both T cells. As expected, an increase in the production of IL-2 was seen when blocking antibodies for PD-1 were used. Blocking with antibodies for I-A^k, CD28, B7.1, and B7.2 lead to a decrease in IL-2 production. Additionally we tested a Th1 and a Th2 T cell clone. Blockade of B7RP-1/ICOS lead to an increased IFN- response in Th1 cells (A.E7) and an increased IL-4 response in Th2 cells (D10.G4.1). Intracellular staining also showed an increase in cytokine production when the B7RP-1/ICOS pathway was blocked. In conclusion, the B7RP-1/ICOS pathway is negatively regulating T cell activation by B cells and may play a role similar to that of the PD-L1/PD-1 pathway.