Reaction of cationic groups of chlorpromazine with anionic macromolecules: complexes with DNA, RNA, hyaluronic acid and heparin

Prolonged activity of the pestiviral RNase Erns as an interferon antagonist after uptake by clathrin-mediated endocytosis

The RNase activity of the envelope glycoprotein E(rns) of the pestivirus bovine viral diarrhea virus (BVDV) is required to block type I interferon (IFN) synthesis induced by single-stranded RNA (ssRNA) and double-stranded RNA (dsRNA) in bovine cells. Due to the presence of an unusual membrane anchor at its C terminus, a significant portion of E(rns) is also secreted. In addition, a binding site for cell surface glycosaminoglycans is located within the C-terminal region of E(rns). Here, we show that the activity of soluble E(rns) as an IFN antagonist is not restricted to bovine cells. Extracellularly applied E(rns) protein bound to cell surface glycosaminoglycans and was internalized into the cells within 1 h of incubation by an energy-dependent mechanism that could be blocked by inhibitors of clathrin-dependent endocytosis. E(rns) mutants that lacked the C-terminal membrane anchor retained RNase activity but lost most of their intracellular activity as an IFN antagonist. Surprisingly, once taken up into the cells, E(rns) remained active and blocked dsRNA-induced IFN synthesis for several days. Thus, we propose that E(rns) acts as an enzymatically active decoy receptor that degrades extracellularly added viral RNA mainly in endolysosomal compartments that might otherwise activate intracellular pattern recognition receptors (PRRs) in order to maintain a state of innate immunotolerance.

IMPORTANCE

The pestiviral RNase E(rns) was previously shown to inhibit viral ssRNA- and dsRNA-induced interferon (IFN) synthesis. However, the localization of E(rns) at or inside the cells, its species specificity, and its mechanism of interaction with cell membranes in order to block the host's innate immune response are still largely unknown. Here, we provide strong evidence that the pestiviral RNase E(rns) is taken up within minutes by clathrin-mediated endocytosis and that this uptake is mostly dependent on the glycosaminoglycan binding site located within the C-terminal end of the protein. Remarkably, the inhibitory activity of E(rns) remains for several days, indicating the very potent and prolonged effect of a viral IFN antagonist. This novel mechanism of an enzymatically active decoy receptor that degrades a major viral pathogen-associated molecular pattern (PAMP) might be required to efficiently maintain innate and, thus, also adaptive immunotolerance, and it might well be relevant beyond the bovine species.

Ethanol-induced mast cell-mediated inflammation leads to increased susceptibility of intestinal tumorigenesis in the APC Δ468 min mouse model of colon cancer

BACKGROUND

Chronic and frequent alcohol (ethanol [EtOH]) intake has been associated with an increased incidence of several types of cancers including breast, mouth, throat, esophageal, stomach, and colorectal (CRC). The underlying mechanism of this deleterious carcinogenic effect of alcohol has not been clearly established but inflammation may be 1 unifying feature of these cancers. We have recently shown that intestinal mast cells play a central role in intestinal carcinogenesis. In this study, we tested our hypothesis that mast cell-mediated inflammation is 1 underlying mechanism by which chronic alcohol promotes intestinal tumorigenesis.

METHODS

APC(Δ468) mice were fed either an alcohol-containing Nanji liquid diet or isocaloric dextrose-containing Nanji diet for 10 weeks and then sacrificed to collect small and large intestine samples. Assessments of tumor number and size as well as mast cell number and mast cell activity and histology score for invasion were compared between Control (dextrose-fed) and alcohol-fed APC(∆468) mice. The effect of alcohol on mast cell-mediated tumor migration was also assessed using an in vitro migration assay.

RESULTS

Alcohol feeding increased both polyp number and size within both the small and the large intestines of APC(∆468) mice. Only alcohol-fed mice showed evidence of tumor invasion. Chronic alcohol feeding also resulted in an increased mast cell number and activity in tumor stroma and invading borders. In vitro migration assay showed that alcohol significantly increases mast cell-mediated tumor migration in vitro.

CONCLUSIONS

Our data show that chronic alcohol intake promotes: (i) intestinal tumorigenesis and tumor invasion in genetically susceptible mice; (ii) increases in polyp-associated mast cells; and (iii) mast cell-mediated tumor migration in vitro. Both our in vivo and in vitro studies suggest that mast cell-mediated inflammation could be 1 mechanism by which alcohol promotes carcinogenesis.

Photodynamic action of chlorpromazine on adenovirus 5:repairable damage and single strand breaks

Chlorpromazine, a substituted phenothiazine, commonly used as a sedative, has been found to photosensitize the inactivation of human adenovirus 5 to wavelengths of light between 330 and 390 nm. The slope of the inactivation curve is three fold greater when fibroblasts from people having xeroderma pigmentosum (XP) were used as viral hosts than when normal fibroblasts were used, showing that at least two-thirds of the damage produced in the virions is repairable by normal human fibroblasts. The phototreatment of chlorpromazine sensitized virions also results in the production of DNA strand breaks, which correlate fairly well with the production of lethal viral damage as measured in XP fibroblasts. These findings suggest that the photosensitization of the skin observed in patients treated with chlorpromazine might be due to DNA damage.