Showing papers in "Journal of Leukocyte Biology in 1995"
TL;DR: Structural analysis of chemokines has revealed that the alpha/beta structural-fold is highly conserved among both the CXC and CC chemokine classes, allowing identification of high affinity analogs that do not activate the receptor and are potent antagonists.
Abstract: Structural analysis of chemokines has revealed that the alpha/beta structural-fold is highly conserved among both the CXC and CC chemokine classes. Although dimerization and aggregation is often observed, the chemokines function as monomers. The critical receptor binding regions are in the NH2-terminal 20 residues of the protein and are the least ordered in solution. The flexible NH2-terminal region is the most critical receptor binding site and a second site also exists in the loop that follows the two disulfides. The well-ordered regions are not directly involved in receptor binding but, along with the disulfides, they provide a scaffold that determines the conformation of the sites that are critical for receptor binding. These general requirements for function are common to all the chemokines. For the CC chemokines, receptor activation and receptor binding regions are separate within the 10 residue NH2-terminal region. This has allowed identification of high affinity analogs that do not activate the receptor and are potent antagonists.
398 citations
TL;DR: The effects of IFN‐γ on the various cell lineages of the immune system, focusing on the biology of its actions are discussed, and research focused on the consequences of introducing IFN'γ cDNA into tumor cells, aberrant IFN•γ production in transgenic animals, and inhibition of IFn‐γ effects are summarized.
Abstract: In 1965 Wheelock reported that phytohemagglutinin could induce from human leukocytes an interferon-like virus inhibitor [1]. This substance, which turned out to be interferon-gamma (IFN-gamma), has been the subject, directly or indirectly, of thousands of scientific publications since that initial report. Past research has led to the general conclusion that IFN-gamma is much more than an interferon in that it has broader effects on the various arms of the immune system than most any other lymphokine or cytokine. In this review we discuss the effects of IFN-gamma on the various cell lineages of the immune system, focusing on the biology of its actions. In addition, we summarize research focused on the consequences of introducing IFN-gamma cDNA into tumor cells, aberrant IFN-gamma production in transgenic animals, and inhibition of IFN-gamma effects by knocking out either the IFN-gamma gene itself or the IFN-gamma receptor gene.
387 citations
TL;DR: Kinetic studies with both imiquimod and S‐27609 reveal induction of cytokines as early as 1‐4 h after stimulation and provide insight into the mechanism of cytokine induction by these molecules.
Abstract: Imiquimod (R-837, S-26308) and the analogue S-27609 were evaluated for cytokine induction in human blood cells. Both compounds induced interferon-alpha (IFN), tumor necrosis factor-alpha (TNF), interleukin (IL)-1 beta, and IL-6 with S-27609 being 5 to 10 times more potent. Imiquimod and S-27609 also induced IL-1 alpha, IL-1 receptor antagonist, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte CSF (G-CSF), and macrophage inflammatory protein-1 alpha. The profile of cytokines induced by imiquimod and S-27609 was different from those seen with lipopolysaccharide and polyinosinic-polycytidylic acid. Kinetic studies with both imiquimod and S-27609 revealed induction of cytokines as early as 1-4 h after stimulation. Although most of the cytokines produced by S-27609 were secreted, significant concentrations of IL-1 alpha and IL-1 beta remained intracellular. Monocytes were largely responsible for the cytokines produced. Finally, S-27609-induced mRNA expression for TNF, IFN, and IL-8, and this induction did not require protein synthesis. Taken together, these studies extend previous findings by showing induction of additional cytokines and providing insight into the mechanism of cytokine induction by these molecules.
379 citations
TL;DR: The antibiotic peptides of higher eukaryotes merit further study for their role in natural immunity and their potential as novel therapeutic compounds.
Abstract: Gene-encoded peptide antibiotics are ubiquitous components of host defenses in mammals, birds, amphibia, insects, and plants. Their de novo synthesis or release from storage sites can be induced rapidly, which makes them particularly important in the initial phases of resistance to microbial invasion. The endogenous antimicrobial peptides of animals are products of single genes and are synthesized as preproproteins. Multistep processing yields the mature peptide, which generally acts by inducing microbial membrane permeabilization. Several families of antimicrobial peptides have been identified that differ with respect to the presence of disulfide linkages, amino acid composition, structural conformation, and spectrum of activity. The arginine-rich three disulfide-containing beta-sheet defensins are remarkably abundant and widely distributed in animals and plants. The antibiotic peptides of higher eukaryotes merit further study for their role in natural immunity and their potential as novel therapeutic compounds.
337 citations
TL;DR: Tumor‐associated macrophages in the stromal compartment of these tumors and/or malignant epithelial cells were seen to be a major producer cell for these cytokines, whereas tumor necrosis factor‐α receptors were expressed by leukocytes, malignant cells, and endothelial cells in tumor blood vessels.
Abstract: Studies over the past 20 years have established that the development of new capillaries from an existing vascular network (a process called angiogenesis) is an essential component of tumor growth. Malignant tumors do not grow beyond 2-3 mm3 in size unless they stimulate the formation of new blood vessels and thus provide a route for the increased inflow of nutrients and oxygen and outflow of waste products. Tumor angiogenesis also provides an essential exit route for metastasizing tumor cells from the tumor to the bloodstream. Indeed, extensive neovascularization is a poor prognostic factor in several forms of human cancer. Angiogenesis is a complex, multistep process driven by many local signals within the tumor. This involves the degradation of the extracellular matrix around a local venule after the release of collagenases and proteases, the proliferation and migration of capillary endothelial cells, and their differentiation into functioning capillaries. Cytokines produced by various cell types present within the microenvironment of solid tumors form a complex, dynamic network in which they have multiple effects on tumor progression. Herein we review our work on the presence, and possible regulatory influence on tumor angiogenesis, of a number of these cytokines within invasive breast carcinomas. We have combined immunocytochemistry with a single cell cytokine release assay called the reverse hemolytic plaque assay to investigate the cellular sources of the key angiogenic cytokines, vascular endothelial growth factor, basic fibroblast growth factor, and tumor necrosis factor-alpha. Tumor-associated macrophages in the stromal compartment of these tumors and/or malignant epithelial cells were seen to be a major producer cell for these cytokines, whereas tumor necrosis factor-alpha receptors were expressed by leukocytes, malignant cells, and endothelial cells in tumor blood vessels.
281 citations
TL;DR: The results strongly suggest that one mechanism of the anti‐inflammatory action of glucocorticoids is to induce dramatic down‐regulation of L‐selectin and CD18 adhesion molecules on blood neutrophils.
Abstract: The responsiveness of bovine neutrophil L-selectin and CD18 to in vivo glucocorticoid administration was characterized by flow cytometric analysis. Blood was sampled intensively from dairy cows treated for 3 days with placebo, cortisol, or dexamethasone. Immunostaining was performed on whole blood (100 microliters) that was left unstimulated or was stimulated with platelet-activating factor (PAF; 1 microgram/ml blood) prior to incubation with fluorescein isothiocyanate-conjugated monoclonal antibodies against L-selectin and CD18. Results were expressed as the percentage of positive-staining cells and as mean fluorescence intensity (MFI) of those cells. Total leukocyte count and leukocyte differentials were also performed on all blood samples. Dexamethasone caused nearly complete down-regulation of L-selectin (P < .01) on the surface of gated cells and reduced to half the MFI of CD18 (P < .01). Compared with values for the placebo group, dexamethasone began to cause L-selectin down-regulation within 8 h after the first injection and these effects persisted until 48 h after the third injection. This was correlated in time with an acute reduction in the proportion of cells that stained positive for L-selectin (from 98% before dexamethasone injections to a low of 17% by 40 h after the first injection). Dexamethasone also caused leukocytosis and neutrophilia during this time interval. In contrast, CD18 down-regulation was delayed until 16 h after the second dexamethasone injection and persisted for roughly 8 days. However, at no time during the experiment did dexamethasone influence the proportion of gated cells staining positive for CD18 (always 100%). Effects of cortisol were generally similar in pattern to those of dexamethasone but were more subtle and more readily detected when PAF was added to blood prior to immunostaining. These results strongly suggest that one mechanism of the anti-inflammatory action of glucocorticoids is to induce dramatic down-regulation of L-selectin and CD18 adhesion molecules on blood neutrophils.
271 citations
TL;DR: It is hypothesized that angiogenesis associated with tumorigenesis is dependent on members of the C-X-C chemokine family acting as either angiogenic or angiostatic factors, and it is suggested that further elucidation of the biology of C- X-C Chemokines in the context of neovascularization of nonsmall cell lung cancer will permit novel targeted therapy aimed specifically at attenuating tumor growth and metastasis.
Abstract: Lung cancer is the leading cause of malignancy-related mortality in the U.S. and is predicted to increase over the remainder of this decade. Despite attempts to advance early diagnosis and use combination therapies, the clinical response of this cancer yields an overall 5-year survival rate of less than 15%. Clearly, new strategies for therapy are indicated. Although carcinogenesis is complex, tumor growth beyond 1-2 mm3 is dependent on angiogenesis. One of the potential mechanisms that allows for tumorigenesis is dysregulation of the balance of angiogenic and angiostatic factors that favors net neovascularization within the primary tumor. Numerous studies have investigated the role of a variety of molecules in the regulation of angiogenesis. Recently, interleukin-8 (IL-8), a member of the C-X-C chemokine family, has been found to be an angiogenic factor. In contrast, platelet factor 4 (PF4), another C-X-C chemokine, has been shown to have angiostatic properties. It is interesting that the major structural difference between IL-8 and PF4 is the presence of the NH2-terminal ELR (Glu-Leu-Arg) motif that precedes the first cysteine amino acid residue of IL-8 and is important in ligand/receptor interactions. We hypothesize that angiogenesis associated with tumorigenesis is dependent on members of the C-X-C chemokine family acting as either angiogenic or angiostatic factors. This paradigm predicts that the biological balance in the expression of these C-X-C chemokines dictates whether the neoplasm grows and develops metastatic potential or regresses. In this review we discuss our recent laboratory findings that support this contention and suggest that further elucidation of the biology of C-X-C chemokines in the context of neovascularization of nonsmall cell lung cancer will permit novel targeted therapy aimed specifically at attenuating tumor growth and metastasis.
259 citations
TL;DR: It is suggested that ICAM‐1 plays a significant role during the neutrophil‐dependent injury phase after hepatic ischemia and reperfusion and therefore blocking this adhesion molecule may have therapeutic potential against postischemic acute liver failure.
Abstract: The potential role of intercellular adhesion molecule-i (ICAM-1) in the pathogenesis of reperfusion injury was investigated in male Fischer rats subjected to 45 mm of hepatic ischemia and 24 h of reperfusion. ICAM-i mRNA levels increased during ischemia in the ischemic liver lobes; however, during reperfusion mRNA levels increased in both the ischemic and nonischemic lobes. Immunohistochemical evaluation indicated ICAM-i expression only on sinusoidal lining cells in controls; ischemia-reperfusion enhanced ICAM-1 expression in the sinusoids and induced some expression on hepatocytes The monoclonal anti-ICAM-i antibody iA29, but not an immunoglobulin G control antibody, administered at 1 h and 8 h of reperfusion (2 mg/kg) signifIcantly attenuated liver injury as indicated by 51% lower plasma alanine aminotransferase activities and 32-36% less hepatic necrosis at 24 h without affecting reactive oxygen forma- tion by Kupffer cells and hepatic neutrophils. Although 1A29 reduced neutrophil extravasation in a glycogen peritonitis by 60%, the antibody had no signfficant effect on hepatic neutrophil infiltration during reperfusion. These data suggest that ICAM-1 plays a significant role during the neutrophil-dependent injury phase after hepatic ischemia and reperfusion and therefore blocking this adhesion molecule may have therapeutic potential against postischemic acute liver failure J. Leukoc. Biol. 57: 368-374; 1995.
243 citations
TL;DR: Although most cells have specific triggers of apoptosis, the killer T cell seems able to induce apoptosis in any cell it recognizes, and may be modulated both in vitro and in vivo.
Abstract: All cells of the hematopoietic system have finite life spans, shorter by far than that of the host. They end their lives by committing a form of cellular suicide or programmed cell death. The morphology of this process is considerably different from that of necrosis and is called apoptosis. Apoptotic cells undergo a stereotyped sequence of changes, including shrinkage and nuclear collapse. The cell is quickly recognized and eaten by a phagocyte, without the elicitation of an inflammatory response. Although most cells have specific triggers of apoptosis, the killer T cell seems able to induce apoptosis in any cell it recognizes. The process of apoptosis is regulated by cytokines, and may be modulated both in vitro and in vivo.
234 citations
TL;DR: It is reported that synovial membrane (SM) or dermal fibroblasts also express cell surface CD40 in vitro, and CD40 ligation induces fibroblast activation and proliferation.
Abstract: CD40 was originally described as a functionally significant B cell surface molecule. However, CD40 is also expressed on monocytes, dendritic cells, epithelial cells, and basophils. We now report that synovial membrane (SM) or dermal fibroblasts also express cell surface CD40 in vitro. Fibroblast CD40 expression declines with increasing time in culture and recombinant interferon-gamma (rINF-gamma) induces fibroblast CD40 up-regulation. This effect of rINF-gamma is augmented by recombinant interleukin-1 alpha or recombinant tumor necrosis factor-alpha. CD40 expression on fibroblasts is functionally significant because CD40L-CD40 interactions induce SM fibroblast CD54 (intercellular adhesion molecule-1) and CD106 (vascular cell adhesion molecule-1) up-regulation. Moreover, ligation of CD40 augments IL-6 production by SM fibroblasts and induces fibroblasts to proliferate. In addition, rINF-gamma enhances the effect of CD40L-CD40 interactions on fibroblast proliferation. Taken together, these studies show that fibroblasts can express CD40, cytokines can regulate fibroblast CD40 expression, and CD40 ligation induces fibroblast activation and proliferation.
230 citations
TL;DR: Differences in the expression pattern of IL-15 and its receptor compared to the IL-2 system suggest unique in vivo roles for IL-teen, which may contribute to the phenotype of X-linked severe combined immunodeficiency in humans, resulting from mutations in the common gamma chain.
Abstract: Interleukin 15 is a newly discovered cytokine that shares biological activities with IL-2 and, like IL-2, is a member of the four-helix bundle cytokine family. We have shown that IL-15 shares components of the receptor for IL-2: the alpha chain of the IL-2R is not required, but both the beta and gamma chains are needed for IL-15 mediated bioactivities. A defect in IL-15 signaling may therefore contribute to the phenotype of X-linked severe combined immunodeficiency in humans, resulting from mutations in the common gamma chain. Differential ability of cells to bind and respond to IL-2 and IL-15 suggested the existence of an additional IL-15 specific receptor component. We identified an IL-15 specific binding protein (IL-15R alpha) on a murine T cell and isolated the corresponding cDNA. The IL-15R alpha is not a member of the hematopoietin receptor superfamily, but is structurally related to the alpha chain of the IL-2R. Differences in the expression pattern of IL-15 and its receptor compared to the IL-2 system suggest unique in vivo roles for IL-15.
TL;DR: It is shown that broad spectrum synthetic inhibitors of matrix metalloproteinases (MMPs) prevent the processing of the TNF precursor but do not inhibit the release of other cytokines.
Abstract: Tumor necrosis factor-a (TNF-a) is released from a cell membrane-anchored precursor by proteolytic cleavage. We have shown that broad spectrum synthetic inhibitors of matrix metalloproteinases (MMPs) prevent the processing of the TNF precursor but do not inhibit the release of other cytokines. Purified MMPs, strome- lysin, matrilysin, collagenase, and the gelatinases can all cleave a recombinant pro-TNF substrate to yield mature TNF. MMP inhibitors prevent the rise in blood levels of TNF after endotoxin administration in rats and are effec- tive in animal models of inflammatory disease such as adjuvant arthritis. Drugs that inhibit MMP action and TNF release show great promise for the treatment of autoimmune inflammatory diseases. J. Leukoc. BioL 57: 774-777; 1995.
TL;DR: Evidence to be discussed suggests that NO is a redundant, autotoxic, immunosuppressive, and inefficient mediator of macrophage function.
Abstract: The production of nitric oxide (NO) and its role in the anti-tumor and anti-microbial effects of rodent macrophages appears well established. In contrast, the circumstances required for its release from human monocytes/macrophages and its potential role in human pathology remain controversial. Evidence to be discussed suggests that NO is a redundant, autotoxic, immunosuppressive, and inefficient mediator of macrophage function. For these reasons, the expression of nitric oxide synthase as a rapid-response, high-output effector pathway may have been evolved out of the human monocyte/macrophage response repertoire or severely restricted in its expression. Hypothetical roles for a modest and circumscribed production of NO by human macrophages are proposed.
TL;DR: In vitro TauCl inhibited the generation of nitric oxide, prostaglandin E2, tumor necrosis factor α, and interleukin‐6, but TauCl slightly enhanced the release of IL‐1α, and the inhibition of iNOS expression seems to be the major mechanism responsible for suppression of NO formation.
Abstract: Taurine (Tan) is an exceptionally abun- darn free amino acid in the cytosol of inflammatory cells and especially in neutrophils. Taurine protects cells from self-destruction during processes that gen- erate oxidants. The major function of Tau in leuko- cytes is to trap chlorinated oxidants (HOC1). Taurine reacts with HOC1 to produce the long-lived compound taurine chioramine (TauCi). Previously, we have shown that other products of the neutrophil chiorin- ating system are able to modify functions of macro- phages. In this study, we investigated in vitro the influence ofTauCi on the generation of inflammatory mediators by activated macrophages. We have found that TauCi inhibited the generation of nitric oxide, prostaglandin E2, tumor necrosis factor a, and inter- leukin-6, but TauCi slightly enhanced the release of IL-la. The formation of nitrites by interferon-'y-acti- vated macrophages was inhibited by TauCl in a dose- dependent manner. Taurine chioramine also reduced the level of inducible nitric oxide synthase (iNOS) mRNA in macrophages, in a similar concentration- dependent manner. Although our experiments do not exclude a direct effect of TauCl on enzymatic activity of iNOS, the inhibition of iNOS expression seems to be the major mechanism responsible for suppression of NO formation. Finally, we discuss the biological role of TauCl in vivo. We suggest that at the site of inflammation TauCl works as a specific signaling molecule ofactivated neutrophils that coordinates the generation of inflammatory mediators in macro- phages.J. Leukoc. Bin!. 58: 667-674; 1995.
TL;DR: The results indicate that MIP-1 alpha expression is mediated by alveolar macrophage-derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis.
Abstract: Pulmonary fibrosis is the end point ofa chronic inflammatory process characterized by leukocyte recruit- ment and activation, fibroblast proliferation, and in- creased extracellular matrix production. Previous studies ofmodels ofpulmonary fibrosis have investigated the role of cytokines in the evolution of the fibrotic response. The involvement of tumor necrosis factor and interleukin-1 in bleomycin-induced lung injury, a model of idiopathic pulmonary fibrosis, has been well estab- lished, suggesting that cytokines mediate the initiation and maintenance of chronic inflammatory lesions. How- ever, the aforementioned cytokines alone cannot account for the recruitment and activation of specific leukocyte populations found in the bleomycin model. Recently, a family of novel proinflammatory cytokines (chemokines) was cloned and characterized, yielding many putative mediators ofleukocyte functions. Macrophage inflamma- tory protein-la (MIP.la) and monocyte chemoattractant protein-i (MCP-1) belong to the C-C chemotactic cytokine family, a group of low-molecular-weight peptides. These molecules modulate chemotaxis, proliferation, and cy- tokine expression in leukocyte subsets. Our group has investigated the roles of MCP-i and MIP-la in the bleomycin model. Both MCP-1 and MIP-la are expressed in a time-dependent manner after bleomycin challenge, and passive immunization of these animals with either anti-MIPla or anti-MCP-1 antibodies attenuated leuko- cyte accumulation. In addition, we have identified spe- cific cell types expressing MCP-1 or MIP-la by in situ hybridization and immunohistochemical localization, re- spectively. Furthermore, our results indicate that MIP-la expression is mediated by alveolar macrophage-derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis. Finally, anti-MIP-la therapy attenuated fibrosis, providing direct evidence for its involvement in fibrotic pathology. Our work has clearly established that the C-C chemokines MCP-1 and MIP-la are expressed and contribute to the initiation and maintenance ofthe bleomycin-induced pui- monary lesionJ. Leukoc. Biol. 57: 782-787; 1995.
TL;DR: PECAM‐1 has a distinct role in the transendothelial migration phase of leukocyte emigration, independent of the adhesion events on the apical surface, in a murine model of acute inflammation.
Abstract: Platelet/endothelial cell adhesion molecule-1 (PECAM-1, CD31) is a molecule capable of mediating both homophilic and heterophilic adhesion. It is constitutively expressed and concentrated in the lateral borders between endothelial cells and expressed on the surfaces of neutrophils, monocytes, and some T cell subsets, as well as on platelets. In a quantitative in vitro assay, monoclonal antibody against PECAM-1 or soluble recombinant PECAM-1 selectively blocked passage of both neutrophils and monocytes across the endothelial monolayer by 70-90% without interfering with the ability of these cells to bind to the apical endothelial cell surface. These regents worked whether directed against leukocyte PECAM-1 or against endothelial cell PECAM-1 and were not additive, suggesting that a homophilic interaction was occurring. In a murine model of acute inflammation, thioglycollate-induced peritonitis, a monoclonal antibody against mouse PECAM-1 blocked emigration of leukocytes into the peritoneal cavity down to background levels. Examination of peritoneal venules in these mice revealed many leukocytes in apparent contact with the endothelial surface but unable to cross the intima. Thus, PECAM-1 has a distinct role in the transendothelial migration phase of leukocyte emigration, independent of the adhesion events on the apical surface.
TL;DR: Interactions of leukocytes with other cells and various extracellular matrix (ECM) proteins lead to different functional cell responses, including changes in growth, behavior, and differentiation.
Abstract: Leukocytes usually pass through the blood stream as nonadherent cells, but during an immune response and inflammation, they become adherent in order to migrate through tissues. Three families of adhesion molecules, the immunoglobulin family, the selectins, and the integrins, participate in interactions between leukocytes and tissues. Near sites of inflammation, leukocytes initially interact with the endothelium via selectins, causing them to slow down and to roll along the walls of blood vessels. Next, chemoattractans induce the activation of integrins on leukocytes. Finally, activated integrins mediate leukocyte migration through the endothelium into the inflamed site. Interactions of leukocytes with other cells and various extracellular matrix (ECM) proteins lead to different functional cell responses, including changes in growth, behavior, and differentiation. Many of these interactions are mediated by integrins, which "integrate" ECM protein signals with the cytoskeleton and which also act as true receptors that generate biochemical signals within the cell. Changes in pH, cytoplasmic Ca2+ concentration, phosphorylation, and gene induction have all been observed after integrin engagement. Adhesion-mediated gene induction in monocytes is perhaps the best example that integrins initiate signaling cascades in the cell to deliver information from the ECM all the way to the nucleus.
TL;DR: A positional cloning strategy based on genetic and physical mapping, YAC cloning, and exon trapping is used to isolate a candidate gene for Bcg, named Nramp1, which codes for a macrophage‐specific polytopic protein with 12 predicted transmembrane domains and a consensus transport motif.
Abstract: Natural resistance to infection with intracellular parasites is controlled in the mouse by the expression of a locus or group of loci on chromosome 1 alternatively named Bcg, Lsh, and Ity. Bcg affects the capacity of mature tissue macrophages to restrict the intracellular proliferation of ingested parasites in the reticuloendothelial organs of the host during the early phase of infection. This review summarizes our molecular genetic approach to the isolation and characterization of the Bcg locus. We have used a positional cloning strategy based on genetic and physical mapping, YAC cloning, and exon trapping to isolate a candidate gene for Bcg, named Nramp1, which codes for a macrophage-specific polytopic protein with 12 predicted transmembrane domains and a consensus transport motif. Sequence analysis of Nramp1 cDNA clones from 27 Bcgs and Bcgr mouse strains reveals that susceptibility to infection (Bcgs) is associated with a single nonconservative Gly to Asp substitution at position 169 within predicted transmembrane domain 4 of the Nramp protein. Cloning experiments and homology search in available databases demonstrated that the Nramp1 gene belongs to a small gene family with several members in vertebrates and in such distantly related species as yeast and plants. Nramp proteins share a remarkable degree of similarity, with strong amino acid sequence conservation in the transmembrane domains, suggesting a common transport function for the Nramp family. Finally, we generated Nramp1-/- gene knockout mice, and analysis of their phenotypic characteristics established that (1) Nramp1 plays a key role in natural defense against infection with intracellular parasites and therefore demonstrated allelism between Nramp1 and Bcg/Ity/Lsh, (2) Nramp1 functions by a novel cytocidal/cytostatic mechanism distinct from those expressed by the activated macrophage, and (3) the Nramp1Asp169 allele of Bcgs inbred strains is a null allele, pointing to a critical role of this residue in Nramp1 function.
TL;DR: The hypothesis is that the relay of information to the neuroendocrine system represents a sensory function for the immune system wherein leukocytes recognize stimuli that are not recognizable by the central and peripheral nervous systems (i.e., bacteria, tumors, viruses, and antigens).
Abstract: Organisms respond to infection with complex adaptations involving bidirectional communication between the immune and neuroendocrine systems. The idea of intercellular communication between the neuroendocrine and immune systems via common signal molecules has provided a conceptual framework for such crosstalk. The studies to date show that cells of the immune system contain receptors for neuroendocrine hormones and can also be considered a source of pituitary and hypothalamic peptides. The structure and pattern of synthesis of these peptides by leukocytes appear similar to neuroendocrine hormones, although some differences exist. Once secreted, these peptide hormones may function as endogenous regulators of the immune system as well as conveyors of information from the immune to the neuroendocrine system. The plasma hormone concentrations contributed by lymphocytes usually do not reach the levels required when the pituitary gland is the source, but because immune cells are mobile, they have the potential to locally deposit the hormone at the target site. Likewise, other studies show that cells of the neuroendocrine system contain receptors for cytokines and can also be considered a source of cytokines, particularly interleukin-1 (IL-1) and IL-6. In the pituitary IL-1 beta coexists with thyroid stimulating hormone in a subpopulation of thyrotropes, suggesting it may have a role as a pituitary paracrine factor. The cytokines, including IL-1, IL-2, IL-6, interferon-gamma, and tumor necrosis factor, exert profound effects on hypothalamic pituitary axes. It is our hypothesis that the relay of information to the neuroendocrine system represents a sensory function for the immune system wherein leukocytes recognize stimuli that are not recognizable by the central and peripheral nervous systems (i.e., bacteria, tumors, viruses, and antigens). The recognition of such noncognitive stimuli by immunocytes is then converted into information and a physiological change occurs. Future studies into the physiological role that cytokines and neuroendocrine hormones have in these systems will be of considerable interest for both immunologists and endocrinologists.
TL;DR: It is suggested that eosinophil shrinkage during apoptosis is a striking and rapid phenomenon and osmotic changes due to K+ efflux could be responsible, at least in part, of the volume decrease.
Abstract: In the absence of appropriate stimulus, eosinophils in vitro rapidly exhibit the features of apoptotic cells (nuclear pycnosis, cell shrinkage, DNA fragmentation). By using electronic cell sizing, we precisely measured the volume distribution of human eosinophils during apoptosis. We observed that apoptosis of eosinophils was accompanied by a marked cell volume decrease (approximately 60%). Moreover, analysis of the volume distribution in different experimental conditions (kinetics of apoptosis, inhibition of apoptosis by cytokines) revealed that the cell shrinkage, once triggered, was a fast process in which the intermediate states between normal and shrunken volume had a short half-life. As a model of apoptosis, the eosinophil model allowed us to test the hypothesis that apoptotic cell shrinkage was linked to osmotic changes due to leakage of internal ions. Indeed, in the presence of K+ channel blockers, the shrinkage was inhibited in a dose-dependent manner. In conclusion, our results suggest that eosinophil shrinkage during apoptosis is a striking and rapid phenomenon and osmotic changes due to K+ efflux could be responsible, at least in part, of the volume decrease.
TL;DR: The timing of endothelial cell expressed P‐selectin and ICAM‐1 could coordinate neutrophil trafficking during the early stages of reperfusion and demonstrate sequential expression of three major endothelialcell adherence molecules in situ following myocardial ischemia and reperfusions.
Abstract: The time course of endothelial P-selectin, ICAM-1, and E-selectin expression was studied in a feline model of myocardial ischemia and reperfusion. Cats were subjected to 90 mm of myocardial ischemia followed by 0, 10, 20, 60, 150, or 270 mm of reperfusion. At the end of reperfusion, the coronary vasculature was examined immunohistochemically to localize monoclonal antibod- ies (mAbs) PB1.3, RR1/1, and Cy1787 directed against P- selectin, ICAM-1, and E-selectin, respectively. Immuno- histochemical localization for P-selectin, recognized by mAb PBL3, was maximally expressed 20 mm after reper- fusion in 60 ± 6% of coronary venules (P < 0.05 com- pared to non-reperfused controls), and covered 59 ± 3% of the endothelial cell perimeter of immunostained coro- nary venules. Immunolocalization of mAb PB1.3 gradu- ally declined at 60, 150, and 270 mm of reperfusion. Immuno- histochemical localization of mAb RR1/1 (anti-ICAM-1) in endothelial cells of coronary venules was observed to a modest extent in non-ischemic myocardium and at 10, 20, and 60 mm of reperfusion, but was significantly in- creased following 150 and 270 mm of reperfusion (P < 0.05 compared non-reperfused controls). At 270 mm post-reperfusion, mAb RR1/1 was seen in 50 ± 4% of coronary venules. Endothelial immunolocalization of mAb Cy1787 (anti-E-selectin) was only observed in 13 ± 1 and 14 ± 3% of coronary venules after 150 and 270 mm of reperfusion, respectively, suggesting that pronounced expression of E-selectin does not occur wi- thin 270 mm after reperfusion. These results demonstrate sequential expression of three major endothelial cell ad- herence molecules in situ following myocardial ischemia and reperfusion. The timing of endothelial cell expressed P-selectin and ICAM-1 could coordinate neutrophil trafficking during the early stages of reperfusion. J. Leu- koc. Biol. 57: 45-55; 1995.
TL;DR: The data indicate that the MDR occurs in response to both acute nonspecific inflammatory and specific immune delayed hypersensitivity processes and that theMDR may play an important role in Mφ activation.
Abstract: Macrophages (M phi s) undergo a physiological response known as the macrophage disappearance reaction (MDR) in response to certain stimuli in the peritoneal compartment. The types of stimuli that can cause the MDR, the relationship of the MDR to the host immunological response, and the possible role of the MDR in M phi activation are reviewed. The data indicate that the MDR occurs in response to both acute nonspecific inflammatory and specific immune delayed hypersensitivity processes and that the MDR may play an important role in M phi activation.
TL;DR: The recombinant rat MIP‐2 was chemotactic for rat neutrophils but did not stimulate migration of rat alveolar macrophages or human peripheral blood eosinophils or lymphocytes in vitro, and the related rat chemokine, KC/CINC stimulated proliferation of ratal epithelial cells but not fibroblasts in vitro.
Abstract: Macrophage inflammatory protein-2 (MIP-2) is a member of a family of cytokines that play roles in inflammatory, immune, and wound healing responses. To clone the cDNA for rat MIP-2, RNA was isolated from the lungs of Fischer 344 rats after instillation of lipopolysaccharide. Reverse transcription-polymerase chain reaction was performed by using synthetic oligonu- cleotide primers designed from the mouse MIP-2 cDNA sequence. A cDNA containing the coding region of rat MIP-2 was cloned and sequenced. Comparison to the mouse MIP-2 cDNA demonstrated 90.3% homology at the nucleotide level and 86% homology at the amino acid level. The rat MIP-2 cDNA was expressed in Fscherichia coli and protein evaluated for bioactivity. The recombi- nant rat MIP-2 was chemotactic for rat neutrophils but did not stimulate migration of rat alveolar macrophages or human peripheral blood eosinophils or lymphocytes. In addition, the recombinant rat MIP-2 and the related rat chemokine, KC/CINC stimulated proliferation of rat alveolar epithelial cells but not fibroblasts in vitro. J Leukoc. Biol. 58: 359-364, 1995.
Journal Article•
TL;DR: In this article, high numbers of CD30+ T cells were found in the lymph node of a patient suffering from Omenn's syndrome, a rare congenital Th2-mediated immunodeficiency disorder, and high serum levels of sCD30 were observed in some conditions in which a pathogenetic role for Th2 cells has been suggested.
Abstract: CD30 is one of the members of the tumor necrosis factor receptor superfamily, originally described as a marker of Reed-Sternberg and Hodgkin's cells in Hodgkin's lymphoma. CD30 appears to be preferentially expressed on, and its soluble form (sCD30) released by, CD4+ and CD8+ T cell clones capable of producing T helper 2 (Th2)-type cytokines. In noneoplastic conditions, CD30+ T cells are barely detectable in vivo; however, a few allergen-specific CD4+CD30+ T cells inducible to the production of Th2-type cytokines could be sorted out from the circulation of allergic subjects after allergen exposure. Moreover, high numbers of CD30+ T cells were found in the lymph node of a patient suffering from Omenn's syndrome, a rare congenital Th2-mediated immunodeficiency disorder. More importantly, high serum levels of sCD30 were observed in some conditions in which a pathogenetic role for Th2 cells has been suggested, such as Omenn's syndrome, atopy, systemic lupus erythematosus, and after infection with measles virus or human immunodeficiency virus. Thus, detection of CD30+ T cells and/or of increased levels of sCD30 may reflect the presence of immune responses or immune alterations characterized by the prevalent activation of Th2-like cells.
TL;DR: This study investigated the effect of cytokines on human microglial cell O2 ‐ production on stimulation with phorbol myristate acetate and found that astrocytes did not generate detectable O2 on stimulated stimulation, suggesting that reactive oxygen intermediates generated by microglia play a role in host defense and injury within the central nervous system.
Abstract: Reactive oxygen intermediates (e.g., superoxide [O2-]) generated by microglia may play a role in host defense and injury within the central nervous system. We investigated the effect of cytokines on human microglial cell O2- production on stimulation with phorbol myristate acetate. Priming of microglial cell cultures with interferon-gamma or tumor necrosis factor-alpha resulted in a dose- and time-dependent enhancement of O2- production. The priming effects of these cytokines were mediated through a protein kinase C signal transduction pathway. In contrast, astrocytes did not generate detectable O2- on phorbol myristate acetate stimulation. Treatment of microglia with transforming growth factor-beta, interleukin-4, or interleukin-10 suppressed in a dose-dependent manner the priming effects of tumor necrosis factor-alpha and interferon-gamma. The results of this study have implications for understanding the mechanisms by which cytokines and microglia contribute to processes of host defense and neurodegeneration via generation of reactive oxygen intermediates.
TL;DR: The results strongly suggest that the protection against S. enteritidis organ invasion induced by the prophylactic treatment of day‐old chicks with ILK involves activated heterophils which migrate rapidly to the inflammatory stimulus where they phagocytize and kill the bacteria.
Abstract: We have previously shown that increased resistance to Salmonella enteritidis organ infectivity in day-old chicks was conferred by the immunoprophylactic administration of S. enteritidis-immune lymphokines (ILK). This resistance was associated with a significant increase in the number of circulating heterophils 4 h after ILK injection. The objective of the present study was to evaluate heterophil function following the administration of ILK in day-old chicks. Significant increases (P < 0.001) in adherence, chemotaxis, and phagocytosis of S. enteritidis were found with heterophils isolated from ILK-injected chickens compared to the heterophils isolated from birds injected with either pyrogen-free saline or lymphokines from non-immune T cells. After phagocytosis, the heterophils from the ILK-injected chickens were also able to kill significantly greater numbers of S. enteritidis more rapidly than did the heterophils from the saline-injected control birds (within 30 min, control cells killed 21.89% of the bacteria whereas ILK-treated cells killed 88.22%). We also found that the heterophils from the ILK-injected birds were more efficient killers of S. typhimurium, S. gallinarum, and E. coli. These results strongly suggest that the protection against S. enteritidis organ invasion induced by the prophylactic treatment of day-old chicks with ILK involves activated heterophils which migrate rapidly to the inflammatory stimulus where they phagocytize and kill the bacteria.
TL;DR: Intcrleukin‐9 (IL‐9) is a multifunctional cytokine produced by activated TH2 clones in vitro and during TH2‐like T cell responses in vivo and interacts with the γ chain of the IL‐2 receptor for signal transduction.
Abstract: Interleukin-9 (IL-9) is a multifunctional cytokine produced by activated TH2 clones in vitro and during TH2-like T cell responses in vivo. The IL-9 receptor is a member of the hemopoietin receptor superfamily and interacts with the gamma chain of the IL-2 receptor for signal transduction. Various observations indicate that IL-9 is actively involved in mast cell responses by inducing the proliferation and differentiation of these cells. The role of IL-9 in T cell responses is less clear. Although freshly isolated normal T cells do not respond to IL-9, this cytokine induces the proliferation of murine T cell lymphomas in vitro and in vivo overexpression of IL-9 results in the development of thymic lymphomas. In the human, the existence of an IL-9-mediated autocrine loop has been suggested for some malignancies such as Hodgkin's disease. Other potential biological targets for IL-9 include B lymphocytes, hematopoietic progenitors, and immature neuronal cell lines.
TL;DR: Analysis of the requirements for NK cell acti vation in C3H mice revealed that the NK cell response is both interleukin‐2 (IL‐2) and IL‐12 dependent, and these observations support a paradigm of in vivo Th1 cell development that involves IL‐ 12‐depcndcnt stimulation of IFN‐γ production by NK cells.
Abstract: Infection of mice with the protozoan parasite Leishmania major is an established model with which to study the in vivo development of CD4+ Th cell subsets. Interferon-gamma (IFN-gamma), produced by natural killer (NK) cells (AsGM1+, CD4-, CD8-, CD3-), regulates CD4+ T cell subset development and early resistance to L. major. Rapid Th1 cell development and resistance to infection occur in mice that develop an NK cell response early after infection (C3H and immunized BALB/c mice), whereas mice that lack an early NK cell response demonstrate delayed Th1 cell development and enhanced early disease (C57BL/6) or lack detectable Th1 cell development altogether and develop a progressive, fatal infection (BALB/c). Analysis of the requirements for NK cell activation in C3H mice revealed that the NK cell response is both interleukin-2 (IL-2) and IL-12 dependent. Although delayed IL-12 production in C57BL/6 mice precludes NK cell activation, the eventual development of a Th1 response appears to be IL-12 dependent. In contrast, concomitant production of inhibitory factors (IL-4, IL-10, and transforming growth factor beta) with IL-12 and IL-2 prevents NK cell activation in BALB/c mice. Together, these observations support a paradigm of in vivo Th1 cell development that involves IL-12-dependent stimulation of IFN-gamma production by NK cells.
TL;DR: In vitro studies of apoptosis of polymorphonuclear leukocytes are studied extensively in vitro, and diverse inflammatory mediators have been shown to modulate the process; however, analysis of published studies reveals at least one discriminating factor–the use of varied concentrations of PMNs in the experimental design.
Abstract: Apoptosis of polymorphonuclear leukocytes (PMNs) is a critical step in the resolution of tissue inflammation. PMN apoptosis has been studied extensively in vitro, and diverse inflammatory mediators have been shown to modulate the process. The reported effects of interleukin-6 (IL-6) on PMN apoptosis are inconsistent; however, analysis of published studies reveals at least one discriminating factor--the use of varied concentrations of PMNs in the experimental design. Consequently, we hypothesized that the in vitro effects of IL-6 on PMN apoptosis varied with the concentration of PMNs in culture. PMNs isolated from healthy human donors were cultured at concentrations from 1 to 20 x 10(6)/mL, and incubated with IL-6 doses from 1 to 100 ng/mL. PMNs cultured at 1-5 x 10(6)/mL were unaffected by IL-6; in contrast, IL-6 inhibited apoptosis in PMNs cultured at 10-20 x 10(6)/mL, compared with untreated similarly concentrated PMNs. These data suggest caution in interpreting in vitro studies of apoptosis; on the other hand, appropriately designed experiments may help elucidate the regulation of apoptosis in vivo.