Reduction in antiviral activity of human beta interferon by gallic acid.

Gallic acid (GA) is a common part of the human diet, both in the free form and as a metabolite of tannic acid and propyl gallate. Cell cultures were incubated with mixtures of either GA and beta interferon (IFN-beta) (formerly fibroblast IFN) or medium and IFN-beta. The cells were subsequently challenged with virus. The virus plaque yields were greater in cells incubated with IFN-beta and GA than in cells incubated with IFN-beta and medium, indicating that in the former mixture, IFN-beta had lost antiviral activity. The magnitude of the loss was dependent upon the GA concentration. IFN-alpha and IFN-gamma (formerly leukocyte IFN and immune IFN, respectively) were not similarly affected. The effect of GA on IFN-beta could be reversed with 2-mercaptoethanol, suggesting a possible sulfhydryl involvement. Extensive dialysis of IFN-beta-GA mixtures to remove the GA failed to reverse the reduction in antiviral activity. This suggests that a direct and irreversible interaction between IFN-beta and GA took place, reducing the activity of IFN-beta. The significance of this finding with regard to virus infections of the intestine is discussed.     

Nucleic acid as interferon inducer. Its antiviral and antitumor activity.

The results of the present study have demonstrated that dsRNA obtained in the system E. coli--bacteriophage is an interferon inducer and possesses antiviral and antitumoral activities.     

Stabilization of antiviral activity of porcine leukocytic interferon

Unithiol (2,3-dimercaptopropan-sodium sulphonate) has been found to be an effective, nontoxic stabilizer of antiviral activity of labile interferons. The optimum stabilizing concentration of unithiol is 0.07%: at this concentration its protective effect is maximum with the lowest content of the substance. Unithiol at this concentration retains about 66% of the initial antiviral activity in acid medium (pH 2.0) and up to 75% of the initial antiviral activity on mechanical exposure.     

Differential effects of TPA and retinoic acid on cell-cell communication in human bronchial epithelial cells.

Understanding how normal and immortalized bronchial epithelial cells respond to modulators of gap junctional communication will increase our understanding of the process of tumor promotion. In the present study we compared to effects of retinoic acid (RA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) on the rate of fluorescent dye transfer via gap junctions in primary human tracheo-bronchial epithelial cells (TBE) and SV40 large T-antigen immortalized, non-tumorigenic bronchial epithelial cells (BEAS-2B). RA in the physiological range (0.001-1 microM) inhibited cell proliferation (DNA synthesis, mitotic index) more in primary TBE cells than BEAS-2B cells. Also in RA-treated cells, decreased cell proliferation was coupled to decreased gap junctional communication (GJC) in TBE but not in BEAS-2B cells. TPA strongly suppressed GJC and proliferation in primary TBE cells, whereas BEAS-2B exhibited increased GJC and retained a significant fraction of cells undergoing DNA synthesis. Our studies show that an uncoupling of GJC and cell proliferation is associated with a differential response to the growth inhibitory effects of RA and phorbol esters in immortalized compared to primary human bronchial epithelial cells.     

Increased Hox activity mimics the teratogenic effects of excess retinoic acid signaling

Excess retinoic acid (RA) signaling can be teratogenic and result in cardiac birth defects, but the cellular and molecular origins of these defects are not well understood. Excessive RA signaling can completely eliminate heart formation in the zebrafish embryo. However, atrial and ventricular cells are differentially sensitive to more modest increases in RA signaling. Increased Hox activity, downstream of RA signaling, causes phenotypes similar to those resulting from excess RA. These results suggest that Hox activity mediates the differential effects of ectopic RA on atrial and ventricular cardiomyocytes and may underlie the teratogenic effects of RA on the heart. Developmental Dynamics 238:1207–1213, 2009. © 2009 Wiley‐Liss, Inc.     

Tunicamycin treatment inhibits the antiviral activity of interferon in mice

Earlier we reported that tunicamycin (TM) treatment of L cells in vitro significantly enhances the antiviral activity of interferon (IFN) against viruses (such as vesicular stomatitis, Sindbis, and herpes simplex) which bud from membranes. However, no such enhancement of the antiviral activity of IFN by TM was observed against encephalomyocarditis virus (EMCV) (nonbudding). We were interested to know whether TM would similarly enhance the antiviral activity of IFN and IFN inducers in vivo against Semliki Forest virus (SFV) and EMCV infections in mice. It was observed that TM alone (0.001 to 5.0 micrograms per mouse) did not protect mice against infections of SFV and EMCV; instead, TM-treated mice died with virus-specific paralytic symptoms earlier than untreated animals. The enhanced mortality in TM-treated and SFV- or EMCV-infected mice was associated with the concomitant increase in virus titer in brain tissue. IFN significantly protected mice against SFV and EMCV infections. The antiviral protection of mice by IFN against both the viruses was markedly inhibited by TM administration. IFN inducers (polyinosinic acid-polycytidylic acid, 6-MFA [a mixture of proteins, polysaccharides, and double-stranded DNA isolated from Aspergillus ochraceus ATCC 28706]) protected a significant number of mice against SFV infection. However, no such protection was observed in mice injected with a combination of TM and IFN inducer. These results indicate that TM treatment inhibits the antiviral action of IFN or IFN inducers in vivo.     

Cyclic AMP potentiation of interferon antiviral activity and effect of interferon on cellular cyclic AMP levels.

Treatment of L cells with 3 to 10 mM 3':5'-cyclic adenosine monophosphate (cAMP) in the presence of interferon was found to potentiate the development of antiviral activity. The dose response of interferon activity at various time periods in the presence and absence of cAMP indicated that potentiation of interferon activity by cAMP occurred at an early stage in the development of antiviral activity. Among the analogues of cAMP tested for interferon-potentiating activity, only the acylated derivatives were found to be active. Combined L-epinephrine and theophylline treatment of cells elevated cellular cAMP levels and also potentiated interferon-mediated antiviral activity. Interferon was also found to elevate cAMP levels in L cells. This activity was limited to biologically active interferon and antagonized the depression of cAMP associated with vesicular stomatitis virus (VSV) infection of L cells. These observations suggest that some aspects of interferon's biological activity is associated with an alteration in cellular levels of cAMP.     

Oromucosal interferon therapy: marked antiviral and antitumor activity.

Oromucosal administration of murine interferon-alpha/beta (IFN-alpha/beta) or individual recombinant species of murine IFN-alpha, IFN-beta, or IFN-gamma or recombinant human IFN-alpha1-8, which is active in the mouse, exerted a marked antiviral activity in mice challenged systemically with a lethal dose of encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV), or varicella zoster virus (VZV). The effects observed were dose dependent and similar in magnitude to those observed following parenteral administration of the same dose of IFN. No antiviral activity was observed after oromucosal administration of murine IFN-alpha/beta in animals in which the IFN receptor had been inactivated by homologous recombination. In contrast to parenteral treatment, oromucosal IFN therapy was found to be ineffective when IFNs were administered before virus infection. Oromucosal administration of IFN-alpha also exerted a marked antitumor activity in mice injected i.v. with highly malignant Friend erythroleukemia cells or other transplantable tumors, such as L1210 leukemia, which has no known viral etiology, the EL4 tumor, or the highly metastatic B16 melanoma. These results show that high doses of IFN can be administered by the oromucosal route apparently without ill effect, raising the possibility that the oromucosal route will prove to be an effective means of administering high doses of IFN that are clinically effective but poorly tolerated.     

Low interferon binding activity of two human cell lines which respond poorly to the antiviral and antiproliferative activity of interferon

Two human cell lines (HT1080 and MRC5) were found to be resistant to the antiproliferative effects of human interferon α. These cells showed also a reduced antiviral response, when virus yield was measured by a plaque assay. The binding of ¹²⁵I-labeled α interferon to HT1080 and MRC5 cells was greatly reduced, relative to another human cell line (A549) which responded well to the antiproliferative and antiviral activities of interferon. These results suggested that the poor response of HT1080 and MRC5 cells was due to the presence of fewer interferon receptors than in A459 cells. Some functional receptors, however, appeared to be present in HT1080 and MRC5 cells, since treatment with interferon resulted in a slight reduction in virus yield and in a modest increase in 2′,5′-oligo(A) polymerase activity.     

Adverse effects of retinoic acid on embryo development and the selective expression of retinoic acid receptors in mouse blastocysts

BACKGROUND: All-trans retinoic acid (RA), the oxidative metabolite of vitamin A, is essential for normal development. In addition, high levels of RA are teratogenic in many species. We have previously shown that excess RA results in immediate effects on the preimplantation embryo and on blastocyst development. This study was conducted to clarify the long-term survival of mouse blastocyst and the effect of RA on gene expression. METHODS AND RESULTS: Using an in vitro model, we identified the immediate adverse impact of RA on mouse blastocyst development. This involved an inhibition of cell proliferation and growth retardation. Using an in vivo model, we also identified the resorption of postimplanted blastocysts that had been treated with excess RA. Analysis of RA-mediated gene induction was also included. The retinoic acid receptors RARalpha and RARgamma were constitutively expressed in the blastocyst and the inner cell mass, whereas RARbeta was induced upon RA treatment. CONCLUSIONS: This is the first evidence to show the impacts of RA on mouse blastocysts in vitro and any carry-over effects in the uterus. There is a retardation of early postimplantation blastocyst development and then subsequent blastocyst death. Our findings also show that there is some degree of selective induction of retinoic acid receptors when excess RA is administered to the blastocysts.     

Effects of retinoic acid on plasminogen activator activity and cellular proliferation

This paper reports effects of retinoic acid (RA) on the expression of plasminogen activator (PA) activity and their relation to the effects of the vitamin on cellular proliferation. RA at the concentrations of 10 microM ml and 1 microM/ml did not affect PA activity in the cells of human melanoma cell line 10-135 but produced a transient decrease of PA activity as well in two other human melanoma cell lines as in RK 13 and IAR 6-7 cells. Unlike 10-135 cells which were resistant to retinoic acid all the remaining cell lines were susceptible to inhibition of the growth by the vitamin. Replacement of the medium with RA by standard medium produced a reversal of the inhibitory effects of the vitamin on PA activity and cell proliferation.     

Teratogenic effects of retinoic acid on neurulation in mice embryos.

Retinoic acids (RA) are natural chemicals that exert a hormone-like activity and a variety of biological effects on early development of mouse. In this study, the probable teratogenic effects of RA on CNS have been investigated in pregnant mice (n = 20) divided into four groups: (1) untreated controls, (2) controls which received a single dose of DMSO, (3) a group that received 40 mg/kg, and (4) a group that received 60 mg/kg of all-trans RA in DMSO, respectively on the eighth day of gestation. Embryos whose dams had received 40 and 60 mg/kg doses of RA, showed malformations and decreased size. At 40 mg/kg dosage level, 50% of the embryos had closed neural tubes while at 60 mg/kg dosage level the neural tube failed to close. The neuroblast mantle layers were disorganized in the 40 mg/kg and even more in the 60 mg/kg exposed group compared to the controls. In mitosis, the density of chromatin was increased in the 60 mg/kg dose group. Compared to controls the 40 and 60 mg/kg dose groups of RA treated dams decreases in the luminal longitudinal and internal measures were observed. Also the thickness of ventricular, mantle and marginal layers was smaller. Wide intercellular spaces due to the degenerated cells at high doses of RA as well as an accumulation of intercellular fluid were observed. Therefore, the wedge shape of neuroepithelium was abolished, preventing the elevation of the neural wall.     

Oromucosal interferon therapy: relationship between antiviral activity and viral load.

Intraperitoneal (i.p.) administration of 20,000 IU recombinant murine IFN-alpha (rMuIFN-alpha) was highly effective in protecting mice challenged i.p. with doses of encephalomyocarditis virus (EMCV) ranging from 44 to 440 LD(50) (p<0.001). Oromucosal (o.m.) IFN therapy was also found to be effective in protecting mice challenged with a lethal dose of EMCV. Thus, 40% of animals infected with 44 LD(50) of EMCV and treated o.m. with 20,000 IU rMuIFN-alpha survived infection with a mean survival time of 12.0 +/- 2.46 days relative to a mean of 6.11 +/- 0.38 days in the control group (p<0.05). Oromucosal IFN therapy was found to be ineffective, however, in animals infected with higher doses of EMCV (88-440 LD(50)), even though intraperitoneal administration of the same dose of rMuIFN-alpha resulted in the survival of 90%, 50%, and 60% of animals infected with 88, 220, and 440 LD(50) of EMCV, respectively. These results suggest that oromucosal IFN therapy is effective at relatively low viral load only and that the mechanism of action of oromucosal IFN therapy may be different from that of parenterally administered IFN. Our results suggest that oromucosal IFN therapy may be most effective in chronic viral infections as an alternative to parenterally administered IFN, which is clinically effective but poorly tolerated.     

The antiviral activity of amiksin and its effect on the interferon status in hepatitis in mice

A single administration of amixin followed by oral infection with mouse hepatitis virus provided protection of 40%-50% animals for 72 hours and normalized the interferon status. In parallel with decreasing level of virus-induced endogenous interferon the interferon-inhibiting activity of lymphocytes of the infected animals increased and approached normal levels.