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Immune checkpoint blockade (ICB) therapies are revolutionary cancer treatments; however, they only benefit about a third of patients. Therefore, extensive research is underway to find methods to improve their therapeutic efficacy. One avenue of study that has recently emerged is to consider the role the gut microbiome plays in therapeutic success. Several high‐impact studies have repeatedly shown that the presence, composition and level of diversity of the gut flora directly impact cancer treatment outcome in both mice and patients. These studies have also highlighted the danger of using antibiotics shortly before or during cancer treatments. However, there are still several questions that need to be answered, including which bacteria promote the greatest benefit, the mechanisms by which they act and how we can use this information to influence treatment outcome. In this review, we explain how the gut microbiome was realized to be of such importance and propose hypotheses for why gut flora have such a critical impact on ICB therapeutic success. We also describe a hypothetical mechanism involving bacterial translocation out of the gut and into the tumor, whereby the bacteria act in an adjuvant capacity to facilitate an antitumor response. By highlighting key papers in the field, we hope to hasten research on the subject so as to find a means to improve the therapeutic efficacy of these ground‐breaking cancer treatments. [ABSTRACT FROM AUTHOR]

Cross-presentation of apoptotic cell associated antigens by immature dendritic cells prevents the activation of self reactive CD8 T cells. Tolerized self reactive CD8 T cells down-regulate IL-7R expression on their surface. Whether over-expression of IL-7R can reverse their fate and function has not been examined. In this paper, we showed forced expression of IL-7R in OT-I T cells by a transgene enhanced CD8 T cell mediated diabetes in the RIP-mOVA model. Although IL-7R Tg (transgenic) did not completely reverse the deletion of OT-I T cells, it provided a significant survival advantage over w.t OT-I T cells. Furthermore, IL7R Tg OT-I T cells isolated from diabetic pancreata displayed increased production of IFN-γ, higher expression of T-bet, and increased externalization of CD107a. We also found that immature DCs containing apoptotic cells expressed high levels of PDL-1 on their surface. Although IL-7R Tg did not change PD1 expression on activated OT-I cells in vivo, the transgene enabled a significantly lower number of OT-I T cells to induce diabetes in the absence of PDL-1. Our results demonstrated that forced expression of IL-7R not only improved the functionality of tolerized CD8 T cells, it also acted in synergy with PDL-1 deficiency to further promote CD8 T cell cytotoxicity to self antigens. [ABSTRACT FROM AUTHOR]

Background: The B and T cells of the human adaptive immune system leverage a highly diverse repertoire of antigen-specific receptors to protect the human body from pathogens. The sequencing and analysis of immune repertoires is emerging as an important tool to understand immune responses, whether beneficial or harmful (in the case of autoimmunity). However, methods for studying these repertoires, and for directly comparing different immune repertoires, are lacking. Results: In this paper, we present a non-parametric method for directly comparing sequencing repertoires, with the goal of rigorously quantifying differences in V, D, and J gene segment utilization. This method, referred to as the Repertoire Dissimilarity Index (RDI), uses a bootstrapped subsampling approach to account for variance in sequencing depth, and, coupled with a data simulation approach, allows for direct quantification of the average variation between repertoires. We use the RDI method to recapitulate known differences in the formation of the CD4+ and CD8+ T cell repertoires, and further show that antigen-driven activation of naïve CD8+ T cells is more selective than in the CD4+ repertoire, resulting in a more specialized CD8+ memory repertoire. Conclusions: We prove that the RDI method is an accurate and versatile method for comparisons of immune repertoires. The RDI method has been implemented as an R package, and is available for download through Bitbucket. [ABSTRACT FROM AUTHOR]