Efficient vaccines are characterized by the establishment of long-lived memory T cells, including T-helper (effectors and follicular) and T-regulatory cells (Tregs). While the former induces cytotoxic or antibody responses, the latter regulates immune responses by maintaining homeostasis. The role of Tregs in inflammatory conditions is ambiguous and their systematic monitoring in vaccination along with effector T-cells is not instinctive. Recent studies from the cancer field clearly showed that Tregs suppress vaccine-induced immune responses and correlate with poor clinical benefit. In HIV infection, Tregs are needed during acute infection to preserve tissue integrity from an overwhelmed activation, but are not beneficial in chronic infection as they suppress anti-HIV responses. Current assays used to evaluate vaccine-induced specific responses are limited as they do not take into account antigen-specific Tregs. However, new assays, such as the OX40 assay, which allow for the simultaneous detection of a full range of Th-responses including antigen-specific Tregs responses, can overcome these issues. In this review article we will revise the role of Tregs in vaccination and review the recent work performed in the field, including the available tools to monitor them, from novel assays to humanized mouse models. Full article

Adenosine, an immunomodulatory biomolecule, is produced by the ecto-enzymes CD39 (nucleoside triphosphate dephosphorylase) and CD73 (ecto-5'-nucleotidase) by dephosphorylation of extracellular ATP. CD73 is expressed by many cell types during injury, infection and during steady-state conditions. Besides host cells, many bacteria also have CD39-CD73-like machinery, which helps the pathogen subvert the host inflammatory response. The major function for adenosine is anti-inflammatory, and most recent research has focused on adenosine’s control of inflammatory mechanisms underlying various autoimmune diseases (e.g., colitis, arthritis). Although adenosine generated through CD73 provides a feedback to control tissue damage mediated by a host immune response, it can also contribute to immunosuppression. Thus, inflammation can be a double-edged sword: it may harm the host but eventually helps by killing the invading pathogen. The role of adenosine in dampening inflammation has been an area of active research, but the relevance of the CD39/CD73-axis and adenosine receptor signaling in host defense against infection has received less attention. Here, we review our recent knowledge regarding CD73 expression during murine Salmonellosis and Helicobacter-induced gastric infection and its role in disease pathogenesis and bacterial persistence. We also explored a possible role for the CD73/adenosine pathway in regulating innate host defense function during infection. Full article