Although hepatic injury is reported in cases with dengue haemorrhagic fever and dengue shock syndrome, its mechanism remains poorly understood. Several findings suggest that dengue virus (DEN) induces apoptosis of hepatocytes in vivo. In this work, DEN type 2 (DEN-2) strain NGC was shown to induce apoptosis in the hepatic cell line HepG2, and infection of HepG2 cells was found to induce Apo2 ligand (Apo2L, also known as tumour necrosis factor-related apoptosis-inducing ligand or TRAIL) expression. Furthermore, Apo2L/TRAIL induced apoptosis in HepG2 cells, which expressed the Apo2L/TRAIL receptor DR5/TRAIL-R2 on their surface. Analysis of the Apo2L/TRAIL promoter revealed that this gene was activated by DEN-2 infection, whose responsive element was overlapping NF-kB-and Sp1-binding sites located at nt "75 to "65. The proteasome inhibitor N-acetyl-L-leucinyl-L-leucinyl-L-norleucinal (LLnL) inhibited Apo2L/TRAIL mRNA expression, and LLnL and anti-Apo2L/TRAIL antibody inhibited DEN-2-induced apoptosis. It was proposed that DEN infection promotes apoptosis partly through the induction of Apo2L/TRAIL expression. INTRODUCTIONDengue viruses (DENs), mosquito-borne flaviviruses, are major human pathogens affecting about 100 million individuals in tropical and subtropical regions of the world annually, and are classified into four serotypes (dengue virus types 1 to 4, designated here DEN-1, -2, -3 and -4) (Gubler, 1998). All four serotypes of DEN are capable of causing human disease with varying degrees of severity, ranging from asymptomatic infection or dengue fever to the devastating dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). Cardinal signs of DHF and DSS include haemorrhage, abrupt onset of vascular leakage and shock, accompanied by severe thrombocytopenia and massive complement activation (Bokisch et al., 1973;Nimmannitya, 1987). In DHF and DSS, liver involvement is a characteristic disease sign (Bhamarapravati et al., 1967). Hepatic injury is similar to that of the early stages of yellow fever, with an increase in plasma transaminase levels, fatty changes in hepatocytes, Kupffer cell hyperplasia, and centrolobular and midzonal necrosis (Innis, 1995). The most characteristic sign is the presence of acidophilic, or Councilman, bodies, which are apoptotic bodies (Feldmann, 1997) and correspond to those seen in the liver of yellow fever patients. DEN antigens have been detected in both hepatocytes and Kupffer cells (Bhamarapravati et al., 1967;Couvelard et al., 1999;Hall et al., 1991;Kangwanpong et al., 1995;Rosen et al., 1989).Although the pathogenesis of DEN-related disease remains poorly understood, virus-induced cell death may be a crucial pathogenic event. Apoptotic cell death has been implicated as a cytopathological mechanism in response to DEN infection both in vitro and in vivo (Despres et al., 1996(Despres et al., , 1998. During the last stage of apoptosis, cells break up into apoptotic bodies, which are then eliminated by phagocytosis. It has been suggested that apoptosis is an innate de...

BackgroundCrassocephalum crepidioides, a plant distributed in Okinawa Islands, is known in folk medicine; however, its anticancer activity has not been investigated. The aim of this study was to determine the in vitro and in vivo antitumor activities of C. crepidioides on murine Sarcoma 180 (S-180) and related molecular mechanisms.MethodsThe antitumor effect of C. crepidioides was evaluated in S-180-cell-bearing mice. Cell growth was assessed using a colorimetric assay. Nitrite and nitrate levels were measured by colorimetry. The expression levels of inducible NO synthase (iNOS) in murine RAW264.7 macrophages was assessed by reverse transcriptase-polymerase chain reaction. Activation of iNOS promoter was detected by reporter gene. Activation of nuclear factor-κB (NF-κB) was evaluated by electrophoretic mobility shift assay. The role of NF-κB signaling was analyzed using inhibitors of NF-κB and dominant-negative mutants, and Western blot analysis.ResultsC. crepidioides extract delayed tumor growth in S-180-bearing mice. However, it did not inhibit S-180 cell growth in vitro. Supernatant of cultured C. crepidioides-stimulated RAW264.7 macrophages was cytotoxic to S-180 cells. This cytotoxicity was associated with nitric oxide (NO) production. NF-κB signaling pathway was crucial for the transcriptional activation of iNOS gene. Isochlorogenic acid, a component of C. crepidioides, induced NF-κB activation and iNOS expression.ConclusionsThe results highlight the oncolytic and immunopotentiation properties of C. crepidioides mediated through NF-κB-induced release of NO from macrophages.

The development of strains of herpes simplex virus (HSV) resistant to drugs has been reported among the immunocompromised patients. Thus, there is a need to develop new therapeutic agents for HSV infections. We evaluated the anti-HSV activity ofBidens pilosa(B. pilosa), a tropical weed, in tissue culture cells and a mouse model.B. pilosaextract showed potent virucidal activity. It inhibited plaque formation and suppressed virus yield in Vero and RAW 264.7 cells infected with HSV-1 and HSV-2. Both the binding of virus to host cells and penetration of virus into cells were also blocked byB. pilosa. Furthermore,B. pilosawas effective against thymidine kinase-deficient and phosphonoacetate-resistant HSV-1 strains.B. pilosatreatment increased the survival rate of HSV-infected mice and limited the development of skin lesions. Our results indicate thatB. pilosahas anti-HSV activity and is thus a potentially useful medical plant for treatment of HSV infection.

The pathogenic mechanism of human T-cell leukaemia virus type I (HTLV-I)-related pulmonary disease, which involves overexpression of intercellular adhesion molecule-1 (ICAM-1) in lung epithelial cells, was investigated. The supernatant of HTLV-I-infected Tax

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