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Open Access Publications from the University of California

Scholarly Works (6 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2019)

In cancer immunotherapy, T cells expressing chimeric antigen receptors (CAR T) targeting human CD19 (hCD19) antigen have exhibited impressive clinical efficacy against B cell leukemias and lymphomas. However, CAR T cells have been less effective against solid tumors, in part because they enter a hyporesponsive (“exhausted” or “dysfunctional”) state that is triggered by chronic antigen stimulation and characterized by upregulation of several inhibitory receptors and loss of effector function. To identify transcriptional and other regulators contributing to the diminished function of CAR T cells in solid tumors, we developed a mouse model in which recipient mice bearing murine melanoma tumors expressing hCD19 antigen were adoptively transferred with hCD19-reactive CAR T cells. We show that CD8+ CAR-expressing tumor-infiltrating lymphocytes (TILs) and endogenous TILs with low effector function and high expression of inhibitory surface receptors PD-1 and TIM3 exhibit similar profiles of gene expression and chromatin accessibility, associated with secondary activation of the three Nr4a (Nuclear Receptor Subfamily 4 Group A) transcription factors Nr4a1 (Nur77), Nr4a2 (Nurr1) and Nr4a3 (Nor1) by the initiating transcription factor NFAT (nuclear factor of activated T cells). Through a similar comparison of data from human CD8+ TILs and viral antigen specific CD8+ T cells from humans chronically-infected with HIV, we observed high expression of Nr4a transcription factors and enrichment of Nr4a binding motifs in uniquely accessible chromatin regions. Treatment of tumor-bearing mice with CAR T cells lacking all three Nr4a transcription factors (Nr4a TKO) resulted in tumor regression and prolonged survival compared to mice adoptively transferred with Nr4a-sufficient (WT) CAR T cells. Nr4a TKO CAR TILs displayed phenotypes and gene expression profiles characteristic of CD8+ effector T cells, and chromatin regions uniquely accessible in Nr4a TKO CAR TILs compared to wild type were enriched for binding motifs for NFB and AP-1, transcription factors classically involved in T cell activation. Our data identify Nr4a transcription factors as major players in the cell-intrinsic program of T cell hyporesponsiveness and point to Nr4a inhibition as a promising strategy for cancer immunotherapy.

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Cover page: Defining the Role of Nr4a Transcription Factors in CD8+ T Cell Exhaustion Using a Murine CAR T Cell Tumor Model
  • Article
  • Peer Reviewed
UCLA Previously Published Works (2012)
Despite tremendous efforts, development of an effective vaccine against human immunodeficiency virus (HIV) has proved an elusive goal. Recently, however, numerous antibodies have been identified that are capable of neutralizing most circulating HIV strains. These antibodies all exhibit an unusually high level of somatic mutation, presumably owing to extensive affinity maturation over the course of continuous exposure to an evolving antigen. Although substantial effort has focused on the design of immunogens capable of eliciting antibodies de novo that would target similar epitopes, it remains uncertain whether a conventional vaccine will be able to elicit analogues of the existing broadly neutralizing antibodies. As an alternative to immunization, vector-mediated gene transfer could be used to engineer secretion of the existing broadly neutralizing antibodies into the circulation. Here we describe a practical implementation of this approach, which we call vectored immunoprophylaxis (VIP), which in mice induces lifelong expression of these monoclonal antibodies at high concentrations from a single intramuscular injection. This is achieved using a specialized adeno-associated virus vector optimized for the production of full-length antibody from muscle tissue. We show that humanized mice receiving VIP appear to be fully protected from HIV infection, even when challenged intravenously with very high doses of replication-competent virus. Our results suggest that successful translation of this approach to humans may produce effective prophylaxis against HIV.
    Cover page: Antibody-based protection against HIV infection by vectored immunoprophylaxis
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2014)
    The vast majority of new HIV infections result from relatively inefficient transmission of the virus across mucosal surfaces during sexual intercourse. A consequence of this inefficiency is that small numbers of transmitted founder viruses initiate most heterosexual infections. This natural bottleneck to transmission has stimulated efforts to develop interventions that are aimed at blocking this step of the infection process. Despite the promise of this strategy, clinical trials of preexposure prophylaxis have had limited degrees of success in humans, in part because of lack of adherence to the recommended preexposure treatment regimens. In contrast, a number of existing vaccines elicit systemic immunity that protects against mucosal infections, such as the vaccines for influenza and human papilloma virus. We recently demonstrated the ability of vectored immunoprophylaxis (VIP) to prevent intravenous transmission of HIV in humanized mice using broadly neutralizing antibodies. Here we demonstrate that VIP is capable of protecting humanized mice from intravenous as well as vaginal challenge with diverse HIV strains despite repeated exposures. Moreover, animals receiving VIP that expresses a modified VRC07 antibody were completely resistant to repetitive intravaginal challenge by a heterosexually transmitted founder HIV strain, suggesting that VIP may be effective in preventing vaginal transmission of HIV between humans.
      Cover page: Vectored immunoprophylaxis protects humanized mice from mucosal HIV transmission
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2019)
      T cells expressing chimeric antigen receptors (CAR T cells) have shown impressive therapeutic efficacy against leukemias and lymphomas. However, they have not been as effective against solid tumors because they become hyporesponsive ("exhausted" or "dysfunctional") within the tumor microenvironment, with decreased cytokine production and increased expression of several inhibitory surface receptors. Here we define a transcriptional network that mediates CD8+ T cell exhaustion. We show that the high-mobility group (HMG)-box transcription factors TOX and TOX2, as well as members of the NR4A family of nuclear receptors, are targets of the calcium/calcineurin-regulated transcription factor NFAT, even in the absence of its partner AP-1 (FOS-JUN). Using a previously established CAR T cell model, we show that TOX and TOX2 are highly induced in CD8+ CAR+ PD-1high TIM3high ("exhausted") tumor-infiltrating lymphocytes (CAR TILs), and CAR TILs deficient in both TOX and TOX2 (Tox DKO) are more effective than wild-type (WT), TOX-deficient, or TOX2-deficient CAR TILs in suppressing tumor growth and prolonging survival of tumor-bearing mice. Like NR4A-deficient CAR TILs, Tox DKO CAR TILs show increased cytokine expression, decreased expression of inhibitory receptors, and increased accessibility of regions enriched for motifs that bind activation-associated nuclear factor κB (NFκB) and basic region-leucine zipper (bZIP) transcription factors. These data indicate that Tox and Nr4a transcription factors are critical for the transcriptional program of CD8+ T cell exhaustion downstream of NFAT. We provide evidence for positive regulation of NR4A by TOX and of TOX by NR4A, and suggest that disruption of TOX and NR4A expression or activity could be promising strategies for cancer immunotherapy.
        Cover page: TOX and TOX2 transcription factors cooperate with NR4A transcription factors to impose CD8+ T cell exhaustion
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2021)
        Infections are a major complication of obesity, but the mechanisms responsible for impaired defense against microbes are not well understood. Here, we found that adipocyte progenitors were lost from the dermis during diet-induced obesity (DIO) in humans and mice. The loss of adipogenic fibroblasts from mice resulted in less antimicrobial peptide production and greatly increased susceptibility to Staphylococcus aureus infection. The decrease in adipocyte progenitors in DIO mice was explained by expression of transforming growth factor-β (TGFβ) by mature adipocytes that then inhibited adipocyte progenitors and the production of cathelicidin in vitro. Administration of a TGFβ receptor inhibitor or a peroxisome proliferator-activated receptor-γ agonist reversed this inhibition in both cultured adipocyte progenitors and in mice and subsequently restored the capacity of obese mice to defend against S. aureus skin infection. Together, these results explain how obesity promotes dysfunction of the antimicrobial function of reactive dermal adipogenesis and identifies potential therapeutic targets to manage skin infection associated with obesity.
          Cover page: Diet-induced obesity promotes infection by impairment of the innate antimicrobial defense function of dermal adipocyte progenitors
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2015)
          As patient survival drops precipitously from early-stage cancers to late-stage and metastatic cancers, microRNAs that promote relapse and metastasis can serve as prognostic and predictive markers as well as therapeutic targets for chemoprevention. Here we show that miR-1269a promotes colorectal cancer (CRC) metastasis and forms a positive feedback loop with TGF-β signalling. miR-1269a is upregulated in late-stage CRCs, and long-term monitoring of 100 stage II CRC patients revealed that miR-1269a expression in their surgically removed primary tumours is strongly associated with risk of CRC relapse and metastasis. Consistent with clinical observations, miR-1269a significantly increases the ability of CRC cells to invade and metastasize in vivo. TGF-β activates miR-1269 via Sox4, while miR-1269a enhances TGF-β signalling by targeting Smad7 and HOXD10, hence forming a positive feedback loop. Our findings suggest that miR-1269a is a potential marker to inform adjuvant chemotherapy decisions for CRC patients and a potential therapeutic target to deter metastasis.
            Cover page: miR-1269 promotes metastasis and forms a positive feedback loop with TGF-β.
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