Dengue virus-induced apoptosis in hepatic cells is partly mediated by Apo2 ligand/tumour necrosis factor-related apoptosis-inducing ligand

Abstract

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...

Role of ERK1/2 signaling in dengue virus-induced liver injury

“…Table 1 lists those genes exhibiting increased expression (≥1.5 fold) in DENV-infected mice compared to the mock control. TNF-␣, TRAIL and Fas mRNA expression increased 5-fold, 3-fold, and 2-fold, respectively; these results are similar to those obtained from in vitro analysis of apoptosis in DENV-infected hepatic cell lines (Limjindaporn et al, 2007;Matsuda et al, 2005;Nagila et al, 2013). The pro-apoptotic profile of infected cells was also evident by the increased expression of Bid, Bax and Bak, as well as members of the caspase proteolytic cascade, Apaf-1, caspases-4 and caspases-14.…”

“…Inhibition of p38 MAPK in HepG2 cells also reduces TNF-␣ production and apoptosis during DENV infection (Nagila et al, 2013). DENV infection induces apoptosis in HepG2 cells partly through the induction of TRAIL (Matsuda et al, 2005). Hepatitis C virus also uses TRAIL to sensitize hepatocytes to apoptosis (Lan et al, 2008).…”

“…Apoptosis of hepatic cells, which may be related to the pathogenesis of DSS, has been observed both in vitro and in vivo (Couvelard et al, 1999;El-Bacha et al, 2007;Huerre et al, 2001;Limonta et al, 2007;Lin et al, 2008;Marianneau et al, 1998;Morchang et al, 2011;Nagila et al, 2011Nagila et al, , 2013Netsawang et al, 2010;Thongtan et al, 2004). DENV infection promotes apoptosis in the hepatoma cell line, HepG2, partly through the induction of TRAIL, a member of the death receptor pathway (Matsuda et al, 2005). TNF-␣ and Fas signaling also contribute to DENV-mediated apoptosis (Limjindaporn et al, 2007;Nagila et al, 2013).…”

Fulminant hepatitis in dengue haemorrhagic fever

“…Several findings include direct infection of the dengue virus and induction of apoptosis, immune mediated hepatocyte injury by CD4 lymphocyteinduced lysis and cytokine production (Marianneau et al, 1997;Gagnon et al, 1999;Huerre et al, 2001;Matsuda et al, 2005). Unlike conventional viral hepatitis, in dengue infections the level of AST is higher than that of ALT (Kuo et al, 1992).…”

Apoptosis in tissues from fatal dengue shock syndrome

“…In addition, recently it was shown that DENV-2 induces apoptosis in hepatoma cells (HepG2) either by infection or partly mediated by Apo2L/TRAIL. Therefore, DENV infection might cause a local cytokine environment in liver tissue that contributes to induction of apoptosis in non infected hepatocytes (Matsuda et al, 2005).…”