We describe a novel mechanism regulating the tumor endothelial barrier and T cell homing to tumors. Selective expression of the death mediator Fas ligand (FasL/CD95L) was detected in the vasculature of many human and mouse solid tumors but not in normal vasculature, and in these tumors it was associated with scarce CD8+ infiltration and predominance of FoxP3+ T regulatory (Treg) cells. Tumor-derived vascular endothelial growth factor A (VEGF-A), interleukin 10 (IL-10) and prostaglandin E2 (PGE2) cooperatively induced FasL expression on endothelial cells, which acquired the ability to kill effector CD8+ T cells, but not Treg cells, due to higher levels of cFLIP expression in Tregs. In the mouse, genetic or pharmacologic suppression of FasL produced a significant increase in the influx of tumor-rejecting CD8+ over FoxP3+ T cells. Pharmacologic inhibition of VEGF and PGE2 attenuated tumor endothelial FasL expression, produced a significant increase in the influx of tumor-rejecting CD8+ over FoxP3+ T cells, which was FasL-dependent, and led to CD8-dependent tumor growth suppression. Thus, tumor paracrine mechanisms establish a tumor endothelial death barrier, which plays a critical role in establishing immune tolerance and determining the fate of tumors.

Regulatory T cells (Tregs) are found infiltrating tumors in a vast array of tumor types, and tumor-infiltrating Tregs are often associated with a poor clinical outcome. Tregs are potent immunosuppressive cells of the immune system that promote progression of cancer through their ability to limit antitumor immunity and promote angiogenesis. Here, we discuss the ways in which Tregs suppress the antitumor immune response, and elaborate on our recent discovery that Tregs make significant direct contributions to tumor angiogenesis. Further, we highlight several current therapies aimed at the elimination of Tregs within cancer patients. Given the multifaceted role of Tregs in cancer, a greater understanding of their functions will ultimately strengthen future therapies.

Emerging evidence indicates that angiogenesis and immunosuppression frequently occur simultaneously in response to diverse stimuli. Here, we describe a fundamental biological programme that involves the activation of both angiogenesis and immunosuppressive responses, often through the same cell types or soluble factors. We suggest that the initiation of these responses is part of a physiological and homeostatic tissue repair programme, which can be co-opted in pathological states, notably by tumours. This view can help to devise new cancer therapies and may have implications for aseptic tissue injury, pathogen-mediated tissue destruction, chronic inflammation and even reproduction.

Oxidative stress activates the transcription factor NRF2, which in turn binds cis-acting antioxidant response element (ARE) enhancers and induces expression of protective antioxidant genes. In contrast, the transcriptional repressor BACH1 binds ARE-like enhancers in cells naïve to oxidative stress and antagonizes NRF2 binding until it becomes inactivated by pro-oxidants. Here, we describe the dynamic roles of BACH1 and NRF2 in the transcription of the heme oxygenase-1 (HMOX1) gene. HMOX1 induction, elicited by arsenite-mediated oxidative stress, follows inactivation of BACH1 and precedes activation of NRF2. BACH1 repression is dominant over NRF2-mediated HMOX1 transcription and inactivation of BACH1 is a prerequisite for HMOX1 induction. In contrast, thioredoxin reductase 1 (TXNRD1) is regulated by NRF2 but not by BACH1. By comparing the expression levels of HMOX1 with TXNRD1, we show that nuclear accumulation of NRF2 is not necessary for HMOX1 induction; rather, BACH1 inactivation permits NRF2 already present in the nucleus at low basal levels to bind the HMOX1 promoter and elicit HMOX1 induction. Thus, BACH1 confers an additional level of regulation to ARE-dependent genes that reveals a new dimension to the oxidative stress response.

Purpose: Whole tumor lysates are promising antigen sources for dendritic cell (DC) therapy as they contain many relevant immunogenic epitopes to help prevent tumor escape. Two common methods of tumor lysate preparations are freeze-thaw processing and UVB irradiation to induce necrosis and apoptosis, respectively. Hypochlorous acid (HOCl) oxidation is a new method for inducing primary necrosis and enhancing the immunogenicity of tumor cells.Experimental Design: We compared the ability of DCs to engulf three different tumor lysate preparations, produce T-helper 1 (T H 1)-priming cytokines and chemokines, stimulate mixed leukocyte reactions (MLR), and finally elicit T-cell responses capable of controlling tumor growth in vivo.Results: We showed that DCs engulfed HOCl-oxidized lysate most efficiently stimulated robust MLRs, and elicited strong tumor-specific IFN-g secretions in autologous T cells. These DCs produced the highest levels of T H 1-priming cytokines and chemokines, including interleukin (IL)-12. Mice vaccinated with HOCl-oxidized ID8-ova lysate-pulsed DCs developed T-cell responses that effectively controlled tumor growth. Safety, immunogenicity of autologous DCs pulsed with HOCl-oxidized autologous tumor lysate (OCDC vaccine), clinical efficacy, and progression-free survival (PFS) were evaluated in a pilot study of five subjects with recurrent ovarian cancer. OCDC vaccination produced few grade 1 toxicities and elicited potent T-cell responses against known ovarian tumor antigens. Circulating regulatory T cells and serum IL-10 were also reduced. Two subjects experienced durable PFS of 24 months or more after OCDC.Conclusions: This is the first study showing the potential efficacy of a DC vaccine pulsed with HOCloxidized tumor lysate, a novel approach in preparing DC vaccine that is potentially applicable to many cancers.

Chronic obstructive pulmonary disease (COPD) is a lethal progressive lung disease culminating in permanent airway obstruction and alveolar enlargement. Previous studies suggest CTL involvement in COPD progression; however, their precise role remains unknown. Here, we investigated whether the CTL activation receptor NK cell group 2D (NKG2D) contributes to the development of COPD. Using primary murine lung epithelium isolated from mice chronically exposed to cigarette smoke and cultured epithelial cells exposed to cigarette smoke extract in vitro, we demonstrated induced expression of the NKG2D ligand retinoic acid early transcript 1 (RAET1) as well as NKG2D-mediated cytotoxicity. Furthermore, a genetic model of inducible RAET1 expression on mouse pulmonary epithelial cells yielded a severe emphysematous phenotype characterized by epithelial apoptosis and increased CTL activation, which was reversed by blocking NKG2D activation. We also assessed whether NKG2D ligand expression corresponded with pulmonary disease in human patients by staining airway and peripheral lung tissues from never smokers, smokers with normal lung function, and current and former smokers with COPD. NKG2D ligand expression was independent of NKG2D receptor expression in COPD patients, demonstrating that ligand expression is the limiting factor in CTL activation. These results demonstrate that aberrant, persistent NKG2D ligand expression in the pulmonary epithelium contributes to the development of COPD pathologies.

Aberrant blood vessels enable tumor growth, provide a barrier to immune infiltration, and serve as a source of pro-tumorigenic signals. Targeting tumor blood vessels for destruction, or tumor vascular disruption therapy, can therefore provide significant therapeutic benefit. Here we describe the ability of chimeric antigen receptor (CAR)-bearing T cells to recognize human prostate-specific membrane antigen (hPSMA) on endothelial targets in vitro as well as in vivo. CAR T cells were generated using the anti-PSMA scFv, J591, and the intracellular signaling domains: CD3ζ, CD28, and/or CD137/4-1BB. We found that all anti-hPSMA CAR T cells recognized and eliminated PSMA+ endothelial targets in vitro, regardless of the signaling domain. T cells bearing the 3rd generation anti-hPSMA CAR, P28BBζ, were able to recognize and kill primary human endothelial cells isolated from gynecologic cancers. In addition, the P28BBζ CAR T cells mediated regression of hPSMA-expressing vascular neoplasms in mice. Finally, in murine models of ovarian cancers populated by murine vessels expressing hPSMA, the P28BBζ CAR T cells were able to ablate PSMA+ vessels, cause secondary depletion of tumor cells, and reduce tumor burden. Taken together, these results provide strong rationale for the use of CAR T cells as agents of tumor vascular disruption, specifically those targeting PSMA.

The role of adaptive immunity in the development or progression of chronic obstructive pulmonary disease (COPD) remains undefined. Recently, the presence of autoantibodies and autoreactive T cells has been demonstrated in COPD patients. In addition, oligoclonal expansions of lung T cells have been observed in COPD patients, but the overlapping incidence of infections, tumors, and cigarette smoke exposure obscures the antigenic stimulus. We analyzed the TCR V␤ repertoire of CD4 and CD8 T cells purified from the lungs and spleens of mice chronically exposed to cigarette smoke. In a mouse model of COPD, we demonstrate that chronic cigarette smoke exposure causes oligoclonal expansions of T cells isolated from the lungs, but not spleens. TCR V␤ repertoire analyses revealed oligoclonal expansions predominantly occurred in lung CD8 T cells, with preferential usage of V␤7, V␤9, V␤13, and V␤14. Using nucleotide sequence analysis based on J␤ analyses, we demonstrate selection of CDR3 amino acid motifs, which strongly suggests Ag-driven oligoclonal T cell expansion. Analysis of the lung TCR V␤ repertoire of mice with cigarette smoke-induced emphysema, which had undergone smoking cessation for 6 mo, revealed that oligoclonal expansions persisted. This study formally demonstrates that chronic cigarette smoke exposure, alone, causes a persistent adaptive T cell immune response. These findings have important implications for therapeutic approaches in the treatment of COPD, and provide insight into potential mechanisms involved in disease pathogenesis.