Liver-expressed chemokine/CC chemokine ligand 16 attracts eosinophils by interacting with histamine H4 receptor

Liver-expressed chemokine (LEC)/CCL16 is a human CC chemokine that is constitutively expressed by the liver parenchymal cells and present in the normal plasma at high concentrations. Previous studies have shown that CCL16 is a low-affinity ligand for CCR1, CCR2, CCR5, and CCR8 and attracts monocytes and T cells. Recently, a novel histamine receptor termed type 4 (H4) has been identified and shown to be selectively expressed by eosinophils and mast cells. In this study, we demonstrated that CCL16 induced pertussis toxin-sensitive calcium mobilization and chemotaxis in murine L1.2 cells expressing H4 but not those expressing histamine receptor type 1 (H1) or type 2 (H2). CCL16 bound to H4 with a K(d) of 17 nM. By RT-PCR, human and mouse eosinophils express H4 but not H3. Accordingly, CCL16 induced efficient migratory responses in human and mouse eosinophils. Furthermore, the responses of human and mouse eosinophils to CCL16 were effectively suppressed by thioperamide, an antagonist for H3 and H4. Intravenous injection of CCL16 into mice induced a rapid mobilization of eosinophils from bone marrow to peripheral blood, which was also suppressed by thioperamide. Collectively, CCL16 is a novel functional ligand for H4 and may have a role in trafficking of eosinophils.     

The Gtx homeodomain transcription factor exerts neuroprotection using its homeodomain

Certain cases of familial Alzheimer's disease are caused by mutants of amyloid-beta precursor protein (AbetaPP), including V642I-AbetaPP, K595N/M596L-AbetaPP (NL-AbetaPP), A617G-AbetaPP, and L648P-AbetaPP. By using an unbiased functional screening with transfection and expression of a human brain cDNA library, we searched for genes that protect neuronal cells from toxicity by V642I-AbetaPP. One protective clone was identical to the human GTX, a neuronal homeobox gene. Human Gtx (hGtx) inhibited caspase inhibitor-sensitive neuronal cell death not only by V642I-AbetaPP but also by L648P-, NL-, A617G-AbetaPP, apolipoprotein E4, and Abeta. The region of hGtx responsible for this rescue function was specified to be its homeodomain (Lys148-His207). The rescue function was shared by DLX4, a distal-less family gene with a homeodomain only 38.3% homologous to that of hGtx, suggesting that this function would be generally shared by homeodomains. The neuroprotective function of hGtx was attributable to hGtx-stimulated production and secretion of insulin-like growth factor-I. This study provides molecular clues to understand how neuronal cells developmentally regulate themselves against cell death as well as to develop reagents effective in curative therapeutics of Alzheimer's disease.     

Fine needle aspiration cytology of primary epithelioid sarcoma. A report of 2 cases

BACKGROUND: Epithelioid sarcoma is a rare soft part tumor, the cytologic features of which have not been fully elucidated to date. We describe the cytologic features in 2 cases of primary epithelioid sarcoma with samples obtained by fine needle aspiration (FNA). CASES: Case 1 was a 50-year-old male who complained of a small mass in his left palm. Case 2 was a 56-year-old female who presented with a mass on the medial aspect of her right forearm. Preoperative FNA smears in both cases showed loose, aggregated and isolated tumor cells that were round to polygonal, with eccentrically located nuclei, against a background of inflammation and necrosis. The tumor cells showed moderate atypia, irregularity in size and many mitoses. In case 1 a presumptive diagnosis of epithelioid sarcoma was made by FNA cytology, while in case 2, FNA cytology revealed a high grade sarcoma with abundant matrix mimicking osteoids, difficult to differentiate from an extraskeletal osteosarcoma. CONCLUSION: Epithelioid sarcoma may be difficult to differentiate from an extraskeletal osteosarcoma in cases with abundant hyalinized collagen on FNA cytology.     

Lipopolysaccharides induced increases in Fas ligand expression by Kupffer cells via mechanisms dependent on reactive oxygen species

Fas-Fas ligand (FasL)-dependent pathways exert a suppressive effect on inflammatory responses in immune-privileged organs. FasL expression in hepatic Kupffer cells (KC) has been implicated in hepatic immunoregulation. In this study, modulation of FasL expression of KC by endogenous gut-derived bacterial LPS and the role of reactive oxygen species (ROS) as potential mediators of FasL expression in KC were investigated. LPS stimulation of KC resulted in upstream ROS generation and, subsequently, increased FasL expression and consequent Jurkat cell (Fas-positive) apoptosis. The NADPH oxidase and xanthine oxidase enzymatic pathways appear to be major sources of this upstream ROS generation. Increased FasL expression was blocked by antioxidants and by enzymatic blocking of ROS generation. Exogenous administration of H2O2 stimulated KC FasL expression and subsequent Jurkat cell apoptosis. Intracellular endogenous ROS generation may therefore represent an important signal transduction pathway for FasL expression in KC.     

ATP-dependent transport of organic anions into isolated basolateral membrane vesicles from rat intestine

The mechanism for the cellular extrusion of organic anions across the intestinal basolateral membrane was examined using isolated membrane vesicles from rat jejunum, ileum, and colon. It was found that 17beta-estradiol 17beta-D-glucuronide (E217betaG) is taken up in an ATP-dependent manner into the basolateral membrane vesicles (BLMVs) but not into the brush-border or microsomal counterparts. The ATP-dependent uptake of E217betaG into BLMVs from jejunum and ileum was described by a single component with a Km value of 23.5 and 8.31 microM, respectively, whereas that into the BLMVs from colon was described by assuming the presence of high (Km=0.82 microM)- and low-affinity (Km=35.4 microM) components. Taurocholate, 6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl) benzothiazole glucuronide and taurolithocholate sulfate, but not leukotriene C4, were significantly taken up by the BLMVs. In addition to such substrate specificity, the inhibitor sensitivity of the ATP-dependent transport in BLMVs was similar to that of rat multidrug resistance-associated protein 3 (Mrp3), which is located on the basolateral membrane of enterocytes. Together with the fact that the rank order of the extent of the expression of Mrp3 (jejunum < ileum < colon) is in parallel with that of the extent of the transport of ligands, these results suggest that the ATP-dependent uptake of organic anions into isolated intestinal BLMVs is at least partly mediated by Mrp3.     

Enhancement of Amphotericin B Activity Against Candida albicans by Superoxide Radical

This study aimed to examine the involvement of oxidative damage in amphotericin B (AmB) activity against Candida albicans using the superoxide (O2-) generator paraquat (PQ). The effects of PQ on AmB activities against growth, viability, membrane permeability and respiration were examined in a wild-type parent strain (K) and a respiration-deficient mutant (KRD-19) since PQ-induced superoxide generation depends on respiration. In the parent strain, the minimal inhibitory concentration (MIC) of AmB, 0.25 microg/ml, tested with a liquid culture was lowered to 0.025 microg/ml by 1 mM PQ. Such a PQ-induced decrease in the MIC value of AmB was minimal in the mutant. Similar PQ-induced enhancement of AmB activity toward the parent strain was also observed with growth on an agar medium. In viability tests, when candidal cells were exposed to AmB (0.1 microg/ml) for I h, the lethality of AmB was enhanced by 1 mM PQ only in the parent strain. Exogenous superoxide dismutase and catalase failed to diminish the enhancing effect of PQ on the growth inhibitory activity of AmB in the parent strain, suggesting an interaction between superoxide and AmB in candidal cells. The enhancement of AmB activity by PQ, observed preferentially in the wild-type strain, can be explained by extensive superoxide generation depending on respiration. These results suggest that oxidative damage induced by superoxide is involved in AmB activity against C. albicans.     

Protective role of gap junctions in preconditioning against myocardial infarction

The aim of the present study was to examine the hypothesis that acceleration of gap junction (GJ) closure during ischemia contributes to anti-infarct tolerance afforded by preconditioning (PC). First, the effects of PC on GJ communication during ischemia were assessed. Isolated buffer-perfused rabbit hearts were subjected to 5-min global ischemia with or without PC with two cycles of 5-min ischemia/5-min reperfusion or a GJ blocker (2 mM heptanol), and then the tissue excised from the ischemic region was incubated in anoxic buffer containing lucifer yellow (LY; 2.5 mg/ml), a tracer of GJ permeability, for 20 min at 37 degrees C. PC and heptanol significantly reduced the area to which LY was transported in the ischemic myocardium by 39% and by 54%, respectively. In the second series of experiments, three GJ blockers (heptanol, 18beta-glycyrrhetinic acid, and 2,3-butanedione monoxime) infused after the onset of ischemia reduced infarct size after 30-min ischemia/2-h reperfusion to an extent equivalent to that in the case of PC. In the third series of experiments, Western blotting for connexin43 (Cx43) showed that PC shortened the time to the onset of ischemia-induced Cx43 dephosphorylation but reduced the extent of Cx43 dephosphorylation during a 30-min period of ischemia. Calphostin C, a protein kinase C (PKC) inhibitor, abolished preservation of phosphorylated Cx43 but not the early onset of Cx43 dephosphorylation after ischemia in the preconditioned myocardium. These results suggest that PC-induced reduction of GJ permeability during ischemia, presumably by PKC-mediated Cx43 phosphorylation, contributes to infarct size limitation.     

Stimulation of phagocytosis of influenza virus-infected cells through surface desialylation of macrophages by viral neuraminidase

Cells infected with influenza A virus undergo apoptosis and become susceptible to phosphatidylserine-mediated phagocytosis by macrophages. This study was undertaken to elucidate the mechanism underlying our previous finding that the activity of viral neuraminidase (NA) is required for efficient phagocytosis. Treatment of macrophages, not influenza virus-infected cells, with Arthrobacter ureafaciens NA or virus-infected cells expressing viral NA augmented the level of phagocytosis of virus-infected cells but not of latex beads or cells undergoing Fas-induced apoptosis. Oligosaccharides, including sialyllactose, bound to influenza virus-infected cells and inhibited phagocytosis by macrophages. These results indicate that surface desialylation of macrophages by influenza virus NA modulates the mode of association between macrophages and target virus-infected cells and stimulates phosphatidylserine-mediated phagocytosis.