Creation of interferon-alpha8 mutants with amino acid substitutions against interferon-alpha receptor-2 binding sites using phage display system and evaluation of their biologic properties.

In this study, we describe the creation of three interferon-alpha (IFN-alpha)8 mutants with markedly higher antiviral and antiproliferative activities in comparison with those of the wild-type (wt)IFN-alpha8, wtIFN-alpha2, and IFN-con1 using a phage display system. Sequence analysis showed that three out of the six hot-spot amino acid residues of wtIFN-alpha8 known to be important for the interaction with the IFN-alpha receptor-2 (IFNAR-2)-binding sites were substituted to other amino acids and the others remained. Although affinity analysis revealed that the dissociation constant (K(D)) of IFN-alpha8 mutants was almost the same with that of wtIFN-alpha8, furthermore, the rates of association (k(a)) and dissociation (k(d)) were relatively lower. These results suggest that changes in the surface electronic charge of amino acid residues lead to changes in binding affinity and kinetics (prolonged dissociation time) toward the IFNAR-2, resulting in the modification of the biological activity. Moreover, our results demonstrate that the molecular engineering of the IFN-alpha8 provides important insight into action of IFN and also it would be useful in the development of therapeutically prominent IFN preparations than those used in clinical practice.

Role of p53 in the inhibitory effects of interferon-alpha subtypes on proliferation of hepatocellular carcinoma cells.

While interferon-alpha (IFN-alpha) subtypes share a common specific receptor composed of two subunits, interferon-alpha receptor (IFNAR)-1 and IFNAR-2, their subtype activities are exhibited via several intracellular signaling pathways and thus subsequently show different biological effects. Anti-proliferative effects of single treatment with IFN-alpha subtypes or 5-fluorouracil (FU), and of combined treatment with each IFN-alpha subtype and 5-FU were examined on three hepatocellular carcinoma cell lines, HepG2, HLE and PLC/PRF/5. HepG2 and PLC/PRF/5 cells were susceptible to the combination treatment, but HLE cells were not. Proliferation of PLC/PRF/5 cells was also inhibited by the IFN-alpha subtypes singly. In addition, apoptosis was observed in HepG2 cells upon treatment with 5-FU alone and with the combination treatment, and in PLC/PRF/5 cells after single treatment with the IFN-alpha subtypes and after the combination treatment. IFN-alpha subtypes induced cell cycle arrest in the G2/M phase in HepG2 and PLC/PRF/5. Analyses by Western blotting and immunoprecipitation revealed increased p53 phosphorylation in HepG2 and PLC/PRF/5 cells but not in HLE cells after combined treatment. Single treatment with IFN-alpha subtypes promoted p53 activation only in PLC/PRF/5 cells. These results propose that IFN-alpha subtypes induce cells to undergo apoptosis through p53 activation directly and indirectly, in collaboration with 5-FU, further suggesting the presence of distinct signal pathways for IFN-alpha-induced apoptosis.

Inhibition of chlamydia trachomatis growth by human interferon-alpha: mechanisms and synergistic effect with interferon-gamma and tumor necrosis factor-alpha.

We have evaluated the effect of natural human interferon (IFN)-alpha on the growth of chlamydia trachomatis in human epithelial cells in vitro and revealed that IFN-alpha has reduced both growth and infectivity of C. trachomatis. The effect of IFN-alpha was reversed by the addition of exogenous L-tryptophan and iron to the culture medium, suggesting that antichlamydial effect of IFN-alpha was caused by depletion of intracellular tryptophan and iron, both of which are essential for chlamydial growth. When IFN-alpha was combined with another antichlamydial cytokines, IFN-gamma and tumor necrosis factor (TNF)-alpha, the effect was synergistically enhanced. Therefore, IFN-alpha would act coordinately with other cytokines such as IFN-gamma and TNF-alpha, and play an important role in host defense against infection and in the establishment of persistent chlamydial infection of host, in which the organism remains viable, but in a culture-negative state.

Effects of interferon-alpha subtypes on the TH1/TH2 balance in peripheral blood mononuclear cells from patients with hepatitis virus infection-associated liver disorders.

Interferon-alpha (IFN-alpha) has recently been shown to modulate in vitro T helper (Th) 1-driven responses in the peripheral blood mononuclear cells (PBMC) of patients with hepatitis B virus or C virus infection. In this study, we examined the in vitro effects of IFN-alpha subtypes (IFN-alpha1, -alpha2, -alpha5, -alpha8, and -alpha10) on the Th1/Th2 balance in PBMC obtained from patients with hepatitis virus infection-associated liver disorders and chronic hepatitis (CH), in comparison with the effect on healthy control volunteer PBMC. The Th1-type cell percentages and Th1/Th2 ratios were significantly higher in the PBMC of patients when compared with controls both before and after cultivation in vitro, with the IFN-alpha subtypes. The IFNalpha-5 induced an increase in the Th2-type cell percentages in both control and patient PBMC, resulting in that IFN-alpha5 lowered the Th1/Th2 ratio in patients with CH. Furthermore, statistical analysis revealed that IFN-alpha8 significantly promoted an increase in the Th1/Th2 ratios of PBMC from patients with CH and liver cirrhosis (LC) but not that of PBMC from patients with LC-hepatocellular carcinoma (HCC) and HCC. These findings imply that hepatitis virus infection and its disease status modify the effects of IFN-alpha subtypes on Th1 and Th2 immune balance in patients. Our findings should help to elucidate the mechanisms underlying successful IFN therapy for hepatitis virus infection and prevention of hepatocellular carcinogenesis.

Royal jelly inhibits the production of proinflammatory cytokines by activated macrophages.

In this study, we have examined the anti-inflammatory actions of royal jelly (RJ) at a cytokine level. When supernatants of RJ suspensions were added to a culture of mouse peritoneal macrophages stimulated with lipopolysaccharide and IFN-gamma, the production of proinflammatory cytokines, such as TNF-alpha, IL-6, and IL-1, was efficiently inhibited in a dose-dependent manner without having cytotoxic effects on macrophages. This suggests that RJ contains factor(s) responsible for the suppression of proinflammatory cytokine secretion. We named the factor for honeybees RJ-derived anti-inflammatory factor (HBRJ-AIF), and further investigated the molecular aspects of it. Size fractionation study showed that HBRJ-AIF is composed of substances of low (< 5 kDa) and high (> 30 kDa) molecular weights, with the former being a major component. Chromatographic analysis showed that MRJP3 is one candidate for the HBRJ-AIF with high molecular weights. Thus, our results suggest that RJ has anti-inflammatory actions through inhibiting proinflammatory cytokine production by activated macrophages.

Correlation Between Interferon Alpha Receptor Protein Expression and Sensitivity to Interferon Alpha Subtypes in Human Renal Carcinoma Cell Lines.

BACKGROUND: We have previously characterized the antitumor activities and immunological properties of interferon-alpha (IFN-α) subtypes on renal cell carcinoma (RCC). However, the mechanism responsible for the different biologic activities among the IFN-α subtypes is still unclear. To explain the different cellular sensitivities to IFN-α subtypes, detailed expression of the interferon-alpha receptor (IFNAR)-1 and IFNAR-2 subunits on different RCC cell lines was examined and compared with sensitivity of the cell lines to the IFN-α subtypes. MATERIALS AND METHODS: We investigated the antiproliferative effects of natural IFN-α subtypes (IFN-α2 and IFN-α8) using eight RCC cell lines. IFNAR-1 and IFNAR-2 expression were determined by RT-PCR and Western blotting. To determine a possible relationship between IFN activity and IFNAR expression, the correlation between the 50% effective IFN dose (ED50) for growth inhibition and the level of IFNAR expression was statistically examined. RESULTS: We report here that IFN-α8 more potently induced growth inhibition than IFN-α2 in the majority of the RCC cell lines examined, this being in accordance with our previous results. The ED50 value of IFN-α8 was lower than 1000 (IU/ml) in six of the eight cell lines, whereas that of IFN-α2 was lower than 1000 (IU/ml) in three of the eight cell lines. The results of experiments using Western blotting analysis revealed that IFN-α subtype sensitivities were closely correlated with the expression level of IFNAR-2(c), a long form of the IFNAR-2 protein, in seven of the eight cell lines. CONCLUSION: These results suggest that the intensity of IFNAR-2(c) protein expression could be an important prognostic marker for clinical application of particular IFN-α subtypes in RCC.

Major royal jelly protein 3 modulates immune responses in vitro and in vivo.

We have recently shown that royal jelly has potent antiallergic properties in a mouse model of immediate hypersensitivity. However, it is still unclear which components of royal jelly exhibit antiallergic activity. In this study, we have screened for antiallergic factors in royal jelly based on inhibition of IL-4 production by anti-CD3 stimulated spleen cells derived from OVA/alum-immunized mice. Using a series of column chromatographies, we purified a 70 kDa glycoprotein, major royal jelly protein 3 (MRJP3), that suppresses IL-4 production. In in vitro experiments, MRJP3 suppressed the production of not only IL-4 but also that of IL-2 and IFN-gamma by T cells concomitant with inhibition of proliferation. The MRJP3-mediated suppression of IL-4 production was also evident when lymph node cells from OVA/alum-immunized mice were stimulated with OVA plus antigen presenting cells. We next examined the purified suppressive factor on OVA/alum-induced allergic responses in mice. Interestingly, in spite of the antigenicity of MRJP3 itself as an extraneous foreign protein, intraperitoneal administration of MRJP3 inhibited serum anti-OVA IgE and IgG1 levels in immunized mice. In addition, heat-treated soluble MRJP3 treatment reduced its antigenicity while maintaining its inhibitory effects on antibody responses to OVA. These results indicate that MRJP3 can exhibit potent immunoregulatory effects in vitro and in vivo. Furthermore, considering the intriguing immunomodulatory effects of MRJP3, it may be of clinical significance to design MRJP3-derived antiallergic peptides by identifying the associated polypeptide regions.

Th1-mediated intestinal inflammation in Crohn's disease may be induced by activation of lamina propria lymphocytes through synergistic stimulation of interleukin-12 and interleukin-18 without T cell receptor engagement.

OBJECTIVE: The development of T helper type 1 (Th1) CD4+ T cells in the intestinal mucosa is driven by interleukin (IL)-12 produced from activated macrophages and IL-18 produced from activated macrophages and epithelial cells. Each of these two cytokines is important for the mucosal response during intestinal inflammation, but their synergistic effect is not fully understood. To characterize the synergistic effect of IL-12 and IL-18 with respect to human intestinal inflammation, we assessed the effect of IL-12 and IL-18 on lamina propria lymphocytes from normal control subjects (LPL-NL) and patients with Crohn's disease (LPL-CD). METHODS: Expression of IL-12 receptor (IL-12R) beta1, beta2, and IL-18Ralpha in LPLs was analyzed by flow cytometry. The functional activity of IL- 12 and IL-18 was assessed by the effect of recombinant IL-12 and recombinant IL-18 on interferon-gamma production, the proliferative response, and the induction of IL-2R, IL-12R, and IL-18R of LPLs. RESULTS: IL-12Rbeta2 expression was significantly greater in LPL-CD compared with LPL-NL. LPL-NL demonstrated a proliferative response and a significant increase in interferon-gamma production and IL-2Ralpha expression when exposed to both IL- 12 and IL- 18, but neither IL- 12 nor IL-18 were able to induce this response on their own. However, IL-12 and IL-18 produced this response in LPL-CD when administered alone. Moreover, a more pronounced synergistic effect of IL-12 and IL-18 was observed in LPL-CD. The response normally observed after administration of IL-12 and IL-18 was significantly inhibited by anti-IL-2 and anti-IL-2Ralpha monoclonal antibody. Furthermore, IL-12 was observed to upregulate IL-18Ralpha expression in LPL-CD. CONCLUSIONS: These findings suggest that a combination of IL-12 and IL-18 in the absence of T cell receptor engagement may serve as a potent regulatory factor for LPL and contribute to the maintenance and enhancement of chronic inflammation in CD.

Antitumor activity of interleukin-18 against the murine T-cell leukemia/lymphoma EL-4 in syngeneic mice.

Interleukin (IL)-18 induces interferon (IFN)-gamma production by T cells and natural killer (NK) cells, and augments NK cell activity in mouse spleen cell cultures. It has recently been demonstrated that in vivo administration of IL-18 to mice results in considerable antitumor effects against syngeneic Meth A sarcoma. In this study, the antitumor effects of IL-18 against murine T-cell leukemia (EL-4) were evaluated. EL-4 proliferation was resistant in vitro to IL-18 and IFN-gamma. When 4 x 10(6) EL-4 cells were transplanted intravenously, the antitumor effects of IL-18 were not pronounced, and only a slight prolongation of the mean survival times was observed. The antitumor effects of IFN-gamma were even less apparent than those of IL-18. However, when mice were transplanted intravenously with 5 x 10(5) EL-4 cells, the extent of experimental visceral dissemination of EL-4 was markedly reduced in mice treated subcutaneously with IL-18, resulting in an increase in survival time with some mice even cured. Although IL-18 was highly effective at inhibiting the development of EL-4 lymphoma dissemination in C57BL/6 mice, it could not inhibit the development of dissemination in mutant C57BL/6 beige (bg/bg) mice lacking NK cell activity. The efficacy of IL-18 was also significantly reduced in nude mice lacking T cells. These results suggest that antitumor efficacy of IL-18 is mediated primarily by NK cells, but that T cells are also required for the complete antitumor efficacy of IL-18.

Trehalose augments osteoprotegerin production in the FHs74Int human intestinal epithelial cell line.

The disaccharide trehalose has been shown to inhibit both bone loss in ovariectomized mice and excessive osteoclastogenesis in lipopolysaccharide-injected mice. However, the mechanism of osteoclastogenesis inhibition by oral administration of trehalose is still unclear. We report here for the first time that a human intestinal epithelial cell line, FHs74Int, also produces osteoprotegerin (OPG) and that trehalose augments OPG production by this cell line. Thus, these results suggest that trehalose promotes the production of OPG by intestinal epithelial cells, which then acts on bone marrow cells, resulting in the suppression of osteoclastogenesis.

The natural plant product tryptanthrin ameliorates dextran sodium sulfate-induced colitis in mice.

The therapeutic effects of tryptanthrin (TRYP), a natural product from the medicinal plant Polygonum tinctorium, were examined in a murine model of inflammatory bowel disease (IBD). Colitis was induced by 5% dextran sodium sulfate (DSS) in drinking water for 7 days from day 0. TRYP (100 mg/kg) was administered orally suspended in 5% arabia gum everyday from day 3 for 5 days. Histopathological analysis showed reduced colon damage in TRYP-treated mice on day 6; however, colon injury resumed after treatment was stopped. The production of prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) by untreated and treated mouse colon tissues cultured in vitro were mostly unchanged by TRYP treatment. However, mitogen-stimulated spleen cells from TRYP-treated colitic mice produced less interleukin 2 (IL-2) and less interferon-gamma (IFN-gamma) than untreated colitic mouse spleen cells, early after induction of colitis. When colitis was induced with 5% DSS for 7 days and TRYP was given to the mice for 8 days from day 3, TRYP enhanced the survival of the mice but results were not significant. A significant reduction of weight loss was observed in TRYP-treated mice with colitis induced by 5% DSS for 4 days as compared to control mice. Remarkably, whereas 90% of the vehicle-treated mice died from wasting disease, all the TRYP-treated mice survived, suggesting that TRYP may have a therapeutic effect on colitis.