CD40 ligand and tdTomato-armed vaccinia virus for induction of antitumor immune response and tumor imaging

Oncolytic vaccinia virus is an attractive platform for immunotherapy. Oncolysis releases tumor antigens and provides co-stimulatory danger signals. However, arming the virus can improve efficacy further. CD40 ligand (CD40L, CD154) can induce apoptosis of tumor cells and it also triggers several immune mechanisms. One of these is a T-helper type 1 (Th1) response that leads to activation of cytotoxic T-cells and reduction of immune suppression. Therefore, we constructed an oncolytic vaccinia virus expressing hCD40L (vvdd-hCD40L-tdTomato), which in addition features a cDNA expressing the tdTomato fluorochrome for detection of virus, potentially important for biosafety evaluation. We show effective expression of functional CD40L both in vitro and in vivo. In a xenograft model of bladder carcinoma sensitive to CD40L treatment, we show that growth of tumors was significantly inhibited by the oncolysis and apoptosis following both intravenous and intratumoral administration. In a CD40-negative model, CD40L expression did not add potency to vaccinia oncolysis. Tumors treated with vvdd-mCD40L-tdtomato showed enhanced efficacy in a syngenic mouse model and induced recruitment of antigen-presenting cells and lymphocytes at the tumor site. In summary, oncolytic vaccinia virus coding for CD40L mediates multiple antitumor effects including oncolysis, apoptosis and induction of Th1 type T-cell responses.

Gene structure of a new cardiac peptide hormone: a model for heart-specific gene expression

Volume excess and mechanical load lead to the induction of the endocrine activity of the heart. The increased production and secretion of A- and B-type natriuretic peptides (ANP and BNP), in turn, unload the heart due to their physiological effects. To find out the mechanisms of cardiac-specific expression and sensitivity to mechanical stimuli of the natriuretic peptide genes, we have used salmon (Salmo salar) as our model organism, because osmoregulating fish have a particularly well developed defense mechanism against volume excess. We have previously cloned a complementary DNA from salmon heart encoding a novel vasorelaxant cardiac hormone, salmon cardiac peptide (sCP). Its production is restricted to the heart, and its release is very sensitive to mechanical load. We have now cloned the gene encoding sCP. The structure of the gene suggests that sCP may represent an ancestral form of the mammalian natriuretic peptides. Remarkably, despite the large phylogenetic distance, the sCP promoter is as effective as mammalian ANP promoters in cultured neonatal rat atrial cardiomyocytes. Therefore, structural and functional comparisons of the promoters of sCP and ANP provide an excellent means of identifying the elements and transcription factors required for atrial-specific gene expression and the regulation of the endocrine function of the heart. Isolation of the protein product of sCP gene from salmon atrium demonstrated that the storage form of sCP is the prohormone of 126 amino acids. The final processing of the prohormone appears to take place during exocytosis of the secretory granules, as the released and circulating form is the biologically active 29-amino acid sCP.