Macrophage membrane glycoproteins that bind Griffonia simplicifolia I-B4: effect on cytotoxicity and protein secretion

CXCR4 antagonist AMD3100 accelerates impaired wound healing in diabetic mice

The antagonism of CXC-chemokine receptor 4 (CXCR4) with AMD3100 improves cardiac performance after myocardial infarction by augmenting the recruitment of endothelial progenitor cells (EPCs) from the bone marrow to the regenerating vasculature. We investigated whether AMD3100 may accelerate diabetes-impaired wound healing through a similar mechanism. Skin wounds were made on the backs of leptin-receptor–deficient mice and treated with AMD3100 or saline. Fourteen days after treatment, wound closure was significantly more complete in AMD3100-treated mice (AMD3100: 87.0±2.6%, Saline: 33.1±1.8%; P<0.0001) and was accompanied by greater collagen-fiber formation, capillary density, smooth-muscle-containing vessel density, and monocyte/macrophage infiltration. On day 7 after treatment, AMD3100 was associated with higher circulating EPC and macrophage counts and with significantly upregulated mRNA levels of stromal-cell–derived factor 1 and platelet-derived growth-factor B in the wound bed. AMD3100 also promoted macrophage proliferation and phagocytosis and the migration and proliferation of diabetic mouse primary dermal fibroblasts and 3T3 fibroblasts, which express very little CXCR4. In conclusion, a single topical application of AMD3100 promoted wound healing in diabetic mice by increasing cytokine production, mobilizing bone-marrow EPCs, and enhancing the activity of fibroblasts and monocytes/macrophages, thereby increasing both angiogenesis and vasculogenesis. Not all of the AMD3100-mediated effects evolved through CXCR4 antagonism.

Enrichment of human bone marrow mononuclear phagocytes and characterization of macrophage subpopulations by immunoenzymatic double staining

In order to isolate and enrich bone marrow mononuclear phagocytes, we performed magnetic-activated cell sorting using beads coupled to a monoclonal antibody directed against the monocyte/macrophage surface molecule CD14. Colocalization of antigens in single cells was achieved by combining an alkaline phosphatase-anti-alkaline phosphatase and an avidin-biotin complex immunoassay, avoiding the use of peroxidase. Bone marrow macrophages were first labelled by the monoclonal antibody PG-M1 (anti-CD68). Subsequently, cytoplasmic and/or surface double staining by the monoclonal antibodies against HLA-DR and Mac-2 antigen or the lectin GSA-I-B4 was carried out. Whereas HLA-DR was co-expressed by the great majority of PG-M1+ macrophages (84.9%+/-6.9%), only a subpopulation exhibited Mac-2 (69.9%+/-5.9%) antigen or galactoside structures detected by GSA-I-B4 (65.0%+/-6.7%). The latter result differed only slightly from the percentage of GSA-I-B4+ macrophages determined in a previous comparative immunomorphometrical study. Therefore, using our method of isolation and enrichment by magnetic-activated cell sorting, only a negligible portion of macrophages is apparently stimulated, as shown by GSA-I-B4 staining. This methodology seems to be a valuable tool for further studies on the monocyte-macrophage system.

Endogenous apolipoprotein E suppresses LPS-stimulated microglial nitric oxide production

The human apolipoprotein (apo) E4 isoform is associated with an increased risk for Alzheimer's disease (AD) and poor prognosis after acute CNS injury. Addition of human apoE inhibits murine microglial activation in culture, suggesting that microglia might be an important physiological target of apoE. In the present study, we examined the role of endogenous murine apoE in modulating microglial nitric oxide (NO) production following lipopolysaccharide (LPS) stimulation. Brain cultures from apoE-deficient mouse pups showed enhanced NO production relative to cultures from wild-type mice and from transgenic mice expressing the human apoE3 isoform, demonstrating that endogenous apoE produced by glial cultures is capable of inhibiting microglial function. ApoE produced within the brain may suppress microglial reactivity and thus alter the CNS response to acute and chronic injury.

Effect of interferon therapy on bone marrow morphology in chronic myeloid leukemia: a cytochemical and immunohistochemical study of trephine biopsies

The effect of interferon (IFN) therapy on bone marrow features in chronic myeloid leukemia (CML) has been studied on successive trephine biopsies (mean interval 13 +/- 8 months) by cytochemical and immunohistochemical methods in combination with morphometry and in comparison with a control group of patients who received monotherapy by busulfan (BU). Following IFN administration (IFN-alpha frequently in combination with IFN-gamma), there was a decrease in neutrophil granulopoiesis accompanied by a significant expansion of erythroid precursors and increased numbers of hemosiderin-laden macrophages. These changes corresponded with the hematologic response in 21 of the 25 patients investigated. Numbers of megakaryocytes and reticulin/collagen fiber density increased during treatment. Most conspicuously, in responding patients atypical micromegakaryocytes, usually characterizing CML, were partially replaced by normal-sized cells of this lineage. These features are in keeping with the assumption of a reappearance of the normal hematopoietic cell clone as the result of IFN therapy, which was not found in the BU-treated control group. On the other hand, a relevant subpopulation of micromegakaryocytes (about 30%) was still maintained. This result probably relates to the failure to improve myelofibrosis more effectively. Analysis of cell proliferation (proliferating cell nuclear antigen-PCNA) and apoptosis (in situ end labeling) revealed a reduction in PCNA labeling and increased numbers of cells undergoing programmed death. Identification of the activated subset of macrophages (alpha-D-galactosyl residues expression) by appropriate lectin histochemistry disclosed an increase in the number of GSA-I binding cells. These findings were exclusively limited to IFN administration and reflect an inhibitory effect of IFN on cell proliferation and stimulation of programmed cell death. The latter phenomenon probably results in increased phagocytosis of clonally transformed myeloid cells by GSA-I-positive (activated) macrophages.

Species differences in lectin binding to pulmonary cells: Soybean agglutinin (SBA) as a marker of type I alveolar epithelial cells and alveolar macrophages in mini pigs

We compared lectin staining patterns in rat and mini pig tissues of normal and fibrotic (irradiation-induced) lungs. Two lectins were studied: Dolichos biflorus (DBA) and Soybean (SBA). Both lectins strongly stained a subpopulation of alveolar macrophages. In the rat, DBA positive macrophages were a subpopulation of the SBA binding cells. In mini pig lungs, a further specific binding of DBA and SBA was observed: DBA reacted with endothelia, and SBA stained the alveolar type I cells. Double immunofluorescence experiments using a type II cell-specific cytokeratin antibody confirmed the selective reactivity of SBA with type I cells, which was also present in fibrotic areas with epithelial cell proliferation.

Heterogeneous Dolichos biflorus lectin binding to a subset of rat alveolar macrophages in normal and fibrotic lung tissue

The distribution of Dolichos biflorus lectin in the rat lung and during fibrosis after irradiation was investigated by lectin histochemical and electron microscopical techniques and double immunofluorescence labelling with the monoclonal antibodies RM-1 and ED-1. The results indicate a selective reaction of Dolichos biflorus lectin with a subpopulation of alveolar macrophages. No binding of the lectin was detectable in ED-1-positive macrophages but strong staining occurred in a part of the RM-1-positive cell population. In fibrotic lung specimens an increased number of Dolichos biflorus lectin-positive macrophages was found in which focally ED-1 reactive and RM-1 negative cells appeared. The finding of changing lectin binding pattern in a radiation-induced lung model emphasizes the suitability of the Dolichos biflorus lectin as a marker of macrophage activation or functional specialization.

Macrophage membrane glycoprotein binding of Griffonia simplicifolia I-B4 induces TNF-alpha production and a tumoricidal response

Thioglycollate-elicited macrophages (m phi), upon binding the lectin Griffonia simplicifolia IB4 (GSIB4) at the plasma membrane, are induced to secrete several low molecular weight proteins. In this investigation, results from specific ELISA and immunoprecipitation analysis of these molecules confirmed that the cytokine, tumor necrosis factor-alpha (TNF-alpha), belongs to the group of elicited proteins. This specific m phi response is directly influenced by the dose of GSIB4 used and the time in contact with the cells. At 40 micrograms/ml GSIB4, the maximum dose of lectin used, the m phi activity was equal to that achieved when the cells were incubated with an interferon-gamma/lipopolysaccharide (IFN/LPS) stimulus alone. Moreover, the data showed that TNF-mediated tumoricidal activity was significantly influenced by GSIB4 binding to the m phi membrane. When the lectin was incubated alone or in sequence with IFN/LPS, this ligand-receptor binding promoted the lysis of WEHI 164 tumor target cells. However, concurrent incubation of both IFN/LPS and GSIB4 with m phi significantly diminished the tumoricidal response. This suggested that one of the metabolic pathways utilized subsequent to receptor-ligand binding was altered by these interactions. When cyclic AMP (cAMP) and inositol triphosphate (IP3) levels were examined, the results showed that the concentration of cAMP was unchanged despite the fact that IP3 levels were significantly enhanced upon m phi-GSIB4 binding. Collectively, the data show that GSIB4 binding to specific glycoproteins in the m phi membrane induces TNF-alpha production and facilitates TNF-alpha dependent tumoricidal responses. It also appears that the transduction of the signal, in part, at least utilizes the phosphatidyl inositol pathway. Finally, it is noteworthy that m phi activity is influenced by the sequence in which GSIB4 is presented to the m phi relative to the IFN/LPS treatment.