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Inhibition of Fas-mediated fulminant hepatitis in CrmA gene-transfected mice
1Department of Experimental Surgery and Bioengineering, National Children's Medical Research Center, Tokyo, Japan.
Abstract:
Hyperimmune response via Fas/Fas-ligand and perforin/granzyme pathways may be essential in pathogenesis of virus-induced fulminant hepatitis. CrmA inhibits activation of caspases and granzyme B, suggesting it may block these pathways. We investigated whether CrmA expression would inhibit Fas-associated lethal hepatitis in mice. We successfully generated AxCALNLCrmA, a recombinant adenovirus expressing CrmA gene with a Cre-mediated switching cassette. We increased CrmA expression level in the liver transfected with AxCALNLCrmA (10(9) pfu) by increasing administration dose (10(7)-10(9) pfu) of AxCANCre, a recombinant, adenovirus-expressing Cre gene. Injection of anti-Fas antibody into the control mice rapidly led to animal death due to massive liver apoptosis, while the apoptosis was dramatically reduced in the CrmA-expressed mice. The animal survival increased with an increase of CrmA expression. The formation of active caspase-3 was markedly inhibited in the crmA-transfected hepatocytes in vitro. These results suggest that crmA is an effective gene that can inhibit immune-related liver apoptosis.
Insights
Cowpox virus CrmA protein inhibits liver apoptosis, crucial for treating virus-induced fulminant hepatitis. This study demonstrates CrmA
Area of Science:
- Immunology
- Hepatology
- Virology
Background:
- Virus-induced fulminant hepatitis involves hyperimmune responses via Fas/Fas-ligand and perforin/granzyme pathways.
- CrmA ( দ্বারা Cowpox virus protein CrmA) is known to inhibit caspases and granzyme B, suggesting a role in blocking these pathogenic pathways.
Purpose of the Study:
- To investigate the potential of CrmA expression in inhibiting Fas-associated lethal hepatitis in a mouse model.
- To assess the efficacy of a novel recombinant adenovirus vector for CrmA gene delivery to the liver.
Main Methods:
- Generation of AxCALNLCrmA, a recombinant adenovirus expressing the CrmA gene with a Cre-mediated switching cassette.
- Administration of AxCALNLCrmA and AxCANCre (adenovirus expressing Cre recombinase) to mice to achieve liver-specific CrmA expression.
- Induction of hepatitis via anti-Fas antibody injection in control and CrmA-expressing mice.
- Assessment of liver apoptosis, caspase-3 activation, and animal survival rates.
Main Results:
- CrmA expression was successfully increased in mouse livers by adjusting the dose of AxCANCre.
- Anti-Fas antibody injection caused rapid death in control mice due to massive liver apoptosis.
- Liver apoptosis was significantly reduced in mice expressing CrmA, with increased survival rates correlating with CrmA expression levels.
- Active caspase-3 formation was markedly inhibited in CrmA-transfected hepatocytes in vitro.
Conclusions:
- CrmA is an effective gene therapy agent for inhibiting immune-related liver apoptosis.
- The recombinant adenovirus system provides a viable method for delivering CrmA to the liver to mitigate hepatitis.
- Targeting caspase activation with CrmA shows promise for treating severe hepatitis conditions.