Trehalose suppresses lipopolysaccharide-induced osteoclastogenesis bone marrow in mice.

We have previously shown that trehalose suppresses bone loss in ovariectomized (OVX) mice by way of inhibiting osteoclast differentiation in bone marrow. Also, trehalose inhibits the secretion of interleukin-6 in bone marrow cell cultures, resulting in a decrease in osteoclast formation. In this study, we examined the effect of trehalose on osteoclastogenesis using another model of bone resorption, namely lipopolysaccharide (LPS)-stimulated osteoclast induction. Mice were given trehalose (1g/kg) by gastric intubation for 5 consecutive days, and 24 hours later, 14 mg/kg of LPS was injected intraperitoneally. Trehalose significantly suppressed LPS-induced tumor necrosis factor (TNF)-alpha production after 90 min and decreased the number of osteoclasts in the bone marrow 48 hours after LPS injection. These results indicate that trehalose suppresses excessive osteoclastogenesis not only in OVX mice but also in a LPS-induced bone resorption mouse model and further suggest that the latter finding may be mediated at least in part through a decrease in TNF-alpha production.

Pulmonary carcinogenesis induced by ferric nitrilotriacetate in mice and protection from it by Brazilian propolis and artepillin C.

In experiments using the renal carcinogen ferric nitrilotriacetate (Fe-NTA) in male ddY mice, primary pulmonary cancers were also induced in bronchiolar and alveolar tissues. 4-Hydroxy-2-nonenal (4-HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), products of oxidative processes, increased in bronchiolar and alveolar cells after administration of Fe-NTA. These substances disappeared after oral administration of propolis or artepillin C, as shown histochemically, and correlated with an anticancer prophylactic effect of propolis and artepillin C. From our investigation, lipid peroxidation seems to play an important role in pulmonary carcinogenesis. Malignant progression from adenoma of bronchiolar or alveolar origin to malignant tumors has been proposed to involve a stepwise transformation. In our study, adenomas developed into adenocarcinomas and large cell carcinomas after treatment with Fe-NTA. In contrast, after oral administration of propolis or artepillin C, adenomas did not progress to carcinomas. Instead of developing into large cell cancers, as induced by Fe-NTA in control mice, adenomas showed remarkable proliferation of macrophages and local anti-oxidant activity after treatment with either propolis or artepillin C. Propolis and artepillin C therefore appear to inhibit lipid peroxidation and the development of pulmonary cancers.

Apoptosis of human leukemia cells induced by Artepillin C, an active ingredient of Brazilian propolis.

Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is an active ingredient of Brazilian propolis that possesses anti-tumor activity. When Artepillin C was applied to human leukemia cell lines of different phenotypes, namely, lymphocytic leukemia (7 cell lines of T-cell, 5 cell lines of B-cell), myeloid and monocytic leukemia and non-lymphoid non-myeloid leukemia cell lines in vitro, Artepillin C exhibited potent cytocidal effects and induced marked levels of apoptosis in all the cell lines. The most potent effects were observed in the T-cell lines. Apoptotic bodies and DNA fragmentation were induced in the cell lines after exposure to Artepillin C. DNA synthesis in the leukemia cells was clearly inhibited and disintegration of the cells was confirmed microscopically. Apoptosis of the leukemia cells may be partially associated with enhanced Fas antigen expression and loss of mitochondrial membrane potential. In contrast, although Artepillin C inhibited the growth of pokeweed mitogen (PWM)-stimulated normal blood lymphocytes, it was not cytocidal to normal unstimulated lymphocytes. These results suggested that Artepillin C, an active ingredient of Brazilian propolis, has anti-leukemic effects with limited inhibitory effects on normal lymphocytes.

Renal carcinogenesis induced by ferric nitrilotriacetate in mice, and protection from it by Brazilian propolis and artepillin C.

The protective effect of Brazilian propolis and its extract Artepillin C against ferric nitrilotriacetate (Fe-NTA)-induced renal lipid peroxidation and carcinogenesis was studied in male ddY mice. Fe-NTA-induced renal lipid peroxidation leads to a high incidence of renal cell carcinoma (RCC) in mice. Administration of propolis by gastric intubation 2 h before or Artepillin C at either the same time, 2 h, or 5 h before the intraperitoneal injection of Fe-NTA (7 mg Fe/kg) effectively inhibited renal lipid peroxidation. This was evaluated from the measurement of renal thiobarbituric acid-reactive substances (TBARS) or histochemical findings of 4-hydroxy-2-nonenal (4-HNE)-modified proteins and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Repeated injection of Fe-NTA (10 mg Fe/kg per day, twice a week for a total of 16 times in 8 weeks) caused subacute nephrotoxicity as revealed by necrosis and pleomorphic large nuclear cells in the renal proximal tubules, and gave rise to RCC 12 months later. A protective effect from carcinogenicity was observed in mice given propolis or Artepillin C. Furthermore, the mice given Fe-NTA only developed multiple cysts composed of precancerous lesions with multilayered and proliferating large atypical cells. Mice treated with propolis and Artepillin C also had cysts, but these were dilated and composed of flat cells. These results suggest that propolis and Artepillin C prevent oxidative renal damage and the carcinogenesis induced by Fe-NTA in mice.

Interleukin-18 in combination with IL-2 enhances natural killer cell activity without inducing large amounts of IFN-gamma in vivo.

Interleukin-18 (IL-18) is known to synergistically enhance murine natural killer (NK) cell activity in vitro when combined with either IL-12 or IL-2. However, it has also been demonstrated that simultaneous administration of IL-18 and IL-12 to mice induces extraordinarily large amounts of interferon-gamma (IFN-gamma) in the serum. In this study, we examined the effects of a combination of IL-18 and IL-2 on in vivo NK cell activation in parallel with the induction of toxicity. In contrast to the IL-18 and IL-12 combination, the combined administration of IL-18 and IL-2 to BALB/c mice for 3 days induced neither high levels of IFN-gamma production nor other visible side effects. When compared with treatment with IL-18 or IL-2 alone, the combined treatment resulted in a significant increase in the number of DX-5 (pan-NK cells marker)-positive cells in spleens and a marked enhancement of splenic NK activity, as determined by standard cytotoxicity assays. Enhanced splenic cytotoxicity generated in the mice treated with both IL-18 and IL-2 was also observed against syngeneic Colon 26 adenocarcinoma cells. Consistent with this in vitro observation, combined treatment produced a significantly stronger inhibitory effect on the pulmonary metastases following i.v. injection of Colon 26 tumor cells than treatment with either cytokine alone. These results suggest that IL-18 combined with IL-2 potentiates in vivo NK cell activity and contributes to inhibition of tumor metastasis without inducing significant toxicity.

In vivo antitumor effects of murine interferon-gamma-inducing factor/interleukin-18 in mice bearing syngeneic Meth A sarcoma malignant ascites.

Interferon-gamma-inducing factor/interleukin-18 is a novel cytokine that reportedly augments natural killer (NK) activity in human and mouse peripheral blood mononuclear cell cultures in vitro and has recently been designated IL-18. In this study, IL-18 exhibited significant antitumor effects in BALB/c mice challenged intraperitoneally (i.p.) with syngeneic Meth A sarcoma when administered i.p. on days 1, 2 and 3 after challenge. Intravenous (i.v.) administration also induced antitumor effects in the tumor-bearing mice; however, subcutaneous (s.c.) administration did not. When mice were twice pretreated with 1 microg IL-18 3 days and 6 h before tumor challenge, all mice survived whereas control mice died within 3 weeks of challenge. Inhibitory effects on Meth A cell growth in vitro were not observed with either IL-18 or interferon gamma. The effects of IL-18 pretreatment were abrogated by abolition of NK activity after mice had been injected with anti-asialo GM1 antibody 48 h before and, 24 h and 72 h after tumor challenge. Mice pretreated with IL-18 and surviving tumor challenge resisted rechallenge with Meth A cells but could not reject Ehrlich ascites carcinoma, and spleen cells from the resistant mice, but not control mice, exhibited cytotoxic activity against Meth A cells in vitro after restimulation with mitomycin C-treated Meth A cells for 5 days. The effector cells in the spleen cell preparations from resistant mice appear to be CD4+ cells because cytolytic activity was significantly inhibited after depletion of this subset by monoclonal antibodies and complement. In conclusion, IL-18 exhibits in vivo immunologically (primarily NK) mediated antitumor effects in mice challenged with syngeneic Meth A sarcoma and induces immunological memory and the generation of cytotoxic CD4+ cells.