Citations

Abstract Purpose: Reovirus is a naturally occurring oncolytic virus in clinical trials. Although tumor infection by reovirus can generate adaptive antitumor immunity, its therapeutic importance versus direct viral oncolysis is undefined. This study addresses the requirement for viral oncolysis and replication, and the relative importance of antitumor immunity and direct oncolysis in therapy. Experimental Design: Nonantigen specific T cells loaded with reovirus were delivered i.v. to C57BL/6 and severe combined immunodeficient mice bearing lymph node and splenic metastases from the murine melanoma, B16ova, with assessment of viral replication, metastatic clearance by tumor colony outgrowth, and immune priming. Human cytotoxic lymphocyte priming assays were done with dendritic cells loaded with Mel888 cells before the addition of reovirus. Results: B16ova was resistant to direct oncolysis in vitro, and failed to support reovirus replication in vitro or in vivo. Nevertheless, reovirus purged lymph node and splenic metastases in C57BL/6 mice and generated antitumor immunity. In contrast, reovirus failed to reduce tumor burden in severe combined immunodeficient mice bearing either B16ova or reovirus-sensitive B16tk metastases. In the human system, reovirus acted solely as an adjuvant when added to dendritic cells already loaded with Mel888, supporting priming of specific antitumor cytotoxic lymphocyte, in the absence of significant direct tumor oncolysis; UV-treated nonreplicating reovirus was similarly immunogenic. Conclusion: The immune response is critical in mediating the efficacy of reovirus, and does not depend upon direct viral oncolysis or replication. The findings are of direct relevance to fulfilling the potential of this novel anticancer agent.

Recent evidence suggests that the microbial community in the human intestine may play an important role in the pathogenesis of obesity. We examined 184,094 sequences of microbial 16S rRNA genes from PCR amplicons by using the 454 pyrosequencing technology to compare the microbial community structures of 9 individuals, 3 in each of the categories of normal weight, morbidly obese, and post-gastric-bypass surgery. Phylogenetic analysis demonstrated that although the Bacteria in the human intestinal community were highly diverse, they fell mainly into 6 bacterial divisions that had distinct differences in the 3 study groups. Specifically, Firmicutes were dominant in normal-weight and obese individuals but significantly decreased in post-gastric-bypass individuals, who had a proportional increase of Gammaproteobacteria . Numbers of the H 2 -producing Prevotellaceae were highly enriched in the obese individuals. Unlike the highly diverse Bacteria , the Archaea comprised mainly members of the order Methanobacteriales , which are H 2 -oxidizing methanogens. Using real-time PCR, we detected significantly higher numbers of H 2 -utilizing methanogenic Archaea in obese individuals than in normal-weight or post-gastric-bypass individuals. The coexistence of H 2 -producing bacteria with relatively high numbers of H 2 -utilizing methanogenic Archaea in the gastrointestinal tract of obese individuals leads to the hypothesis that interspecies H 2 transfer between bacterial and archaeal species is an important mechanism for increasing energy uptake by the human large intestine in obese persons. The large bacterial population shift seen in the post-gastric-bypass individuals may reflect the double impact of the gut alteration caused by the surgical procedure and the consequent changes in food ingestion and digestion.

Abstract Purpose: The goals of this study were (a) to investigate whether preconditioning of immunocompetent mice with PC-61-mediated regulatory T-cell (Treg) depletion and interleukin-2 (IL-2) would enhance systemic delivery of reovirus into subcutaneous tumors and (b) to test whether cyclophosphamide (CPA), which is clinically approved, could mimic PC-61 for modification of Treg activity for translation into the next generation of clinical trials for intravenous delivery of reovirus. Experimental Design: C57Bl/6 mice bearing subcutaneous B16 tumors were treated with CPA or PC-61 followed by 10 injections of low-dose IL-2. Mice were then treated with intravenous reovirus. Virus localization to tumor and other organs was measured along with tumor growth and systemic toxicity. Results: Preconditioning with PC-61 and IL-2 enhanced localization of intravenous oncolytic reovirus to tumors with significantly increased antitumor therapy compared with controls (P < 0.01). However, with the maximal achievable dose of reovirus, Treg modification + IL-2 was also associated with systemic toxicity. CPA (100 mg/kg) did not deplete, but did functionally inhibit, Treg. CPA also mimicked PC-61, in combination with IL-2, by inducing “hyperactivated” NK cells. Consistent with this, preconditioning with CPA + IL-2 enhanced therapy of intravenously delivered, intermediate-dose reovirus to a level indistinguishable from that induced by PC-61 + IL-2, without any detectable toxicity. Conclusion: With careful reference to ongoing clinical trials with dose escalation of reovirus alone and in combination with CPA, we propose that future clinical trials of CPA + IL-2 + reovirus will allow for both improved levels of virus delivery and increased antitumor efficacy.