Caspase-8 Collaborates with Caspase-11 to Drive Tissue Damage and Execution of Endotoxic Shock.

The execution of shock following high dose E. coli lipopolysaccharide (LPS) or bacterial sepsis in mice required pro-apoptotic caspase-8 in addition to pro-pyroptotic caspase-11 and gasdermin D. Hematopoietic cells produced MyD88- and TRIF-dependent inflammatory cytokines sufficient to initiate shock without any contribution from caspase-8 or caspase-11. Both proteases had to be present to support tumor necrosis factor- and interferon-ß-dependent tissue injury first observed in the small intestine and later in spleen and thymus. Caspase-11 enhanced the activation of caspase-8 and extrinsic cell death machinery within the lower small intestine. Neither caspase-8 nor caspase-11 was individually sufficient for shock. Both caspases collaborated to amplify inflammatory signals associated with tissue damage. Therefore, combined pyroptotic and apoptotic signaling mediated endotoxemia independently of RIPK1 kinase activity and RIPK3 function. These observations bring to light the relevance of tissue compartmentalization to disease processes in vivo where cytokines act in parallel to execute diverse cell death pathways.

Evaluation of adenovirus vectors containing serotype 35 fibers for vaccination.

In contrast to commonly used serotype 5-based adenovirus (Ad) vectors, Ad's containing fibers derived from B-group serotype 35 (Ad5/35) efficiently transduce human DCs ex vivo and appear to target antigen-presenting cells after intravenous injection into baboons. Based on this, Ad5/35 vectors could be valuable tools for immunotherapy and vaccination. On the other hand, a number of studies indicate that signaling through the B-group Ad receptor, CD46, can cause tolerance or immunosuppression. Since mice do not express CD46 in a human-like pattern, we studied the in vivo properties of Ad5/35 in transgenic mice that express CD46 in a pattern and at a level similar to those of humans. Hypersensitivity assays and analyses of frequencies of regulatory T cells and T cell responses did not indicate that Ad5/35 injection exerts detrimental effects on the host's immune system. An Ad5/35 vector expressing a model antigen was able to trigger a strong T cell response against the test antigen after intramuscular injection. Overall, compared to Ad5 vectors, Ad5/35 vectors had a better safety profile, reflected by lower serum levels of proinflammatory cytokines.

Development and assessment of human adenovirus type 11 as a gene transfer vector.

Adenovirus vectors based on human serotype 5 (Ad5) have successfully been used as gene transfer vectors in many gene therapy-based approaches to treat disease. Despite their widespread application, many potential therapeutic applications are limited by the widespread prevalence of vector-neutralizing antibodies within the human population and the inability of Ad5-based vectors to transduce important therapeutic target cell types. In an attempt to circumvent these problems, we have developed Ad vectors based on human Ad serotype 11 (Ad11), since the prevalence of neutralizing antibodies to Ad11 in humans is low. E1-deleted Ad11 vector genomes were generated by homologous recombination in 293 cells expressing the Ad11-E1B55K protein or by recombination in Escherichia coli. E1-deleted Ad11 genomes did not display transforming activity in rodent cells. Transduction of primary human CD34+ hematopoietic progenitor cells and immature dendritic cells was more efficient with Ad11 vectors than with Ad5 vectors. Thirty minutes after intravenous injection into mice that express one of the Ad11 receptors (CD46), we found, in a pattern and at a level comparable to what is found in humans, Ad11 vector genomes in all analyzed organs, with the highest amounts in liver, lung, kidney, and spleen. Neither Ad11 genomes nor Ad11 vector-mediated transgene expression were, however, detected at 72 h postinfusion. A large number of Ad11 particles were also found to be associated with circulating blood cells. We also discovered differences in in vitro transduction efficiencies and in vivo biodistributions between Ad11 vectors and chimeric Ad5 vectors possessing Ad11 fibers, indicating that Ad11 capsid proteins other than fibers influence viral infectivity and tropism. Overall, our study provides a basis for the application of Ad11 vectors for in vitro and in vivo gene transfer and for gaining an understanding of the factors that determine Ad tropism.