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No description available.

The Lyme disease spirochete Borrelia burgdorferi is the only known human pathogen that directly activates invariant natural killer T (iNKT) cells. The number and activation kinetics of iNKT cells vary greatly among different strains of mice. Here, we report the role of the iNKT cell response in the pathogenesis of Lyme disease using C57BL/6 (B6) mice, a strain with optimal iNKT cell activation that is resistant to the development of spirochetal-induced inflammation. During experimental infection of B6 mice with B. burgdorferi , iNKT cells localize to the inflamed heart where they are activated by CD1d-expressing macrophages. Activation of iNKT cells in vivo results in the production of IFNγ, which we demonstrate controls the severity of murine Lyme carditis by at least two mechanisms. First, IFNγ greatly enhances the recognition of B. burgdorferi by macrophages, leading to increased phagocytosis of the spirochete. Secondly, IFNγ activation of macrophages increases the surface expression of CD1d, thereby facilitating further iNKT activation. Collectively, our data demonstrate that in the resistant background, B6, iNKT cells modulate acute murine Lyme carditis through the action of IFNγ, which appears to self-renew through a positive feedback loop during infection. Inflammation during infection with B. burgdorferi is dependent on the ability of the spirochete to evade local mechanisms of clearance. Even though macrophages are the main infiltrating cell during Lyme carditis, the identification of a receptor capable of mediating phagocytosis of B. burgdorferi has been elusive. Here, we demonstrate that the integrin CR3 is able to mediate binding to the spirochete and facilitate phagocytosis in a complement-dependent and independent manner. Expression of CR3, but not CR4, in CHO cells markedly enhanced their capacity to interact with B. burgdorferi , in the absence and presence of complement opsonization. Furthermore, the interaction between CR3 and B. burgdorferi is dependent on the metal-ion-dependent adhesion site (MIDAS) and could be blocked with EDTA. Inhibition of CR3 with blocking antibody was able to completely abrogate phagocytosis of B. burgdorferi by the macrophage-like RAW264.7 cells and partially block uptake by bone marrow-derived macrophages (BMMs), a finding that was recapitulated with CD11b-deficient BMMs. We further show that activation with recombinant IFNγ increases the transcription of CD11b and CD18, which correlates with increased surface expression of CR3, and that the effect of IFNγ on the phagocytosis of B. burgdorferi is circumscribed to CR3 activity, because inhibition of CR3 is able to completely diminish the effect of IFNγ on the phagocytosis of the B. burgdorferi . Lastly, our results demonstrate that CR3 is a negative regulator of proinflammatory cytokine induction in macrophages responding to B. burgdorferi . Overall, our data demonstrate roles for CR3 in the binding, phagocytosis and proinflammatory cytokine elicited by B. burgdorferi and shed light on the role of IFNγ in mediating the clearance of the spirochete during Lyme disease.

Oncolytic viruses (OVs) are promising tumor-selective treatments, and the efficacy of OV therapies has been shown to depend heavily on the successful delivery and spread of these agents within the tumor mass to generate profound immunostimulatory effects. We have previously reported the potential of vanadium-based compounds such as vanadyl sulfate (VS) as immune-stimulatory enhancers of OV immunotherapy. These compounds, in conjunction with RNA-based OVs such as oncolytic VSVΔ51, improve viral spread and oncolysis, leading to long-term antitumor immunity and prolonged survival in resistant tumor models as previously reported. This effect is associated with a virus-induced antiviral type I IFN response shifting towards a type II IFN response. Here, the systemic impact and the relevant immunological changes following VS/VSVΔ51 combination therapy were investigated to understand the immunological mechanism of action leading to improved antitumor responses. We screened for the secretion of chemokines and cytokines in vivo to understand the mechanism of action regulating the recruitment of immune cells to the tumor in the CT26WT tumor model following treatment. Additionally, the antigen-specific immune response was investigated to further identify the relevant immunological changes following treatment with the VS+VSVΔ51 combination. Our data revealed that VS+VSVΔ51 combination therapy significantly increased the levels of IFN-γ and IL-6, and other key important pro-inflammatory cytokines and chemokines. Improved tumor antigen-specific T-cell responses were observed following the combined therapy. Supported by relevant immunological changes and as a proof of concept for the design of more effective therapeutic regimens, we found that local delivery of VSVΔ51 encoded with IL-12 or with other transgenes in combination with VS further improved therapeutic outcomes in a syngeneic CT26WT colon cancer model. We found that CD8+ T cells and Natural Killer (NK) cells play significant roles in establishing the therapeutic efficacy that we observed; Furthermore, engineering new and targeted therapeutic platforms to impact the antitumor immune response further improves the therapeutic benefits of the combined therapy.

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No description available.

Natural Killer cells are a type of lymphocyte belonging to the innate immune system and they operate cell-mediated cytotoxicity and release of pro-inflammatory cytokines against cancerous cells. However, in vivo testings have shown a reduced activity of NK cells against solid tumors probably due to the negative influence of the immunosuppressive tumor microenvironment. Multicellular tumor spheroids may constitute an advantageous model in cancer biology for studying the mechanisms behind cancer immune editing since it more closely mimics the complexity of the human body compared with the 2D model counterpart. This study investigated the interaction between NK cells isolated from blood and tumor spheroids obtained from A498 renal carcinoma cells, using light-sheet microscopy imaging which allows satisfactory cell tracking in the inner layers of the spheroids. NK cells not only indeed interact with tumor spheroids, but many of them were able to penetrate the spheroids inducing some changes in the structure of the latter. NK cells were also tracked over time, displaying the migration path and calculating the speed. The fluorescence intensity of the NK cells was found reduced as soon as they penetrate the spheroid but, conversely, the speed seems to increase inside the spheroid, a possible sign of the fallibility of the tracking algorithm in this specific case. We propose solutions for more sophisticated future implementations, involving the use of marks during the experimental phase and drift corrections at the data analysis level.

Type I interferons (IFN) are a potent antiviral cytokine group that are key regulators of the immune response against virus infection. Not only does this group activate antiviral states within target cells, it can modulate the innate immune response. In the studies presented, we investigate the effects of type I IFN on the innate immune system during a mucosal vaginal virus infection, herpes simplex virus type 2 (HSV-2), a prominent sexually transmitted infection that causes genital herpes and increases risk of human immunodeficiency virus acquisition. It is well known that type I IFN is critical for natural killer (NK) cell activation. These cells contribute to the antiviral response by suppressing virus replication and aiding in the initiation of the adaptive immune response, particularly through the release of IFN-γ. In the work presented, we demonstrate that type I IFN does not act on NK cells directly for their activation, but instead activates NK cell IFN-γ production by inducing inflammatory monocytes to release IL-18, which in turn, signals NK cells to release IFN-γ during a mucosal HSV-2 infection. Rather, direct action of type I IFN on NK cells serves to negatively regulate their IFN-γ response. We also found that type I IFN was critical for suppressing virus-induced innate immunopathology during HSV-2 infection. Overall, our studies further our understanding of type I IFN and the many roles it plays during virus infection, which has become more relevant as specific therapies altering type I IFN are being used in the clinic. Further, we provide a fundamental understanding of type I IFN and its ability to shape the innate immune response to virus infection by suppressing dysregulated and immunopathological functions while promoting beneficial innate immune responses that can help fight the infection. / Thesis / Doctor of Philosophy (PhD) / Type I interferons (IFN) are a group of proteins that are rapidly produced early during infection and is important for combatting virus infections. We show that type I IFN is not just an antiviral molecule, but can modulate the initial immune response to virus infection. As part of the initial immune response, Natural killer (NK) cells are immune cells that respond rapidly to infection and are a key element in controlling the early stages of infection. We found that type I IFN is critical for activating NK cell function by signaling through an intermediary cell, but can also suppress that same function by directly acting on NK cells. We also found that type I IFN is critical for suppressing a dysregulated immune response that causes severe virus-induced vaginal pathology. Overall, our data suggests that type I IFN is a key antiviral molecule that shapes the immune response to virus infection.