PD-L1 engagement on T cells promotes self-tolerance and suppression of neighboring macrophages and effector T cells in cancer.

Programmed cell death protein 1 (PD-1) ligation delimits immunogenic responses in T cells. However, the consequences of programmed cell death 1 ligand 1 (PD-L1) ligation in T cells are uncertain. We found that T cell expression of PD-L1 in cancer was regulated by tumor antigen and sterile inflammatory cues. PD-L1+ T cells exerted tumor-promoting tolerance via three distinct mechanisms: (1) binding of PD-L1 induced STAT3-dependent 'back-signaling' in CD4+ T cells, which prevented activation, reduced TH1-polarization and directed TH17-differentiation. PD-L1 signaling also induced an anergic T-bet-IFN-γ- phenotype in CD8+ T cells and was equally suppressive compared to PD-1 signaling; (2) PD-L1+ T cells restrained effector T cells via the canonical PD-L1-PD-1 axis and were sufficient to accelerate tumorigenesis, even in the absence of endogenous PD-L1; (3) PD-L1+ T cells engaged PD-1+ macrophages, inducing an alternative M2-like program, which had crippling effects on adaptive antitumor immunity. Collectively, we demonstrate that PD-L1+ T cells have diverse tolerogenic effects on tumor immunity.

Integrating IL-12 mRNA nanotechnology with SBRT eliminates T cell exhaustion in preclinical models of pancreatic cancer.

Pronounced T cell exhaustion characterizes immunosuppressive tumors, with the tumor microenvironment (TME) employing multiple mechanisms to elicit this suppression. Traditional immunotherapies, such as immune checkpoint blockade, often fail due to their focus primarily on T cells. To overcome this, we utilized a proinflammatory cytokine, interleukin (IL)-12, that re-wires the immunosuppressive TME by inducing T cell effector function while also repolarizing immunosuppressive myeloid cells. Due to toxicities observed with systemic administration of this cytokine, we utilized lipid nanoparticles encapsulating mRNA encoding IL-12 for intratumoral injection. This strategy has been proven safe and tolerable in early clinical trials for solid malignancies. We report an unprecedented loss of exhausted T cells and the emergence of an activated phenotype in murine pancreatic ductal adenocarcinoma (PDAC) treated with stereotactic body radiation therapy (SBRT) and IL-12mRNA. Our mechanistic findings reveal that each treatment modality contributes to the T cell response differently, with SBRT expanding the T cell receptor repertoire and IL-12mRNA promoting robust T cell proliferation and effector status. This distinctive T cell signature mediated marked growth reductions and long-term survival in local and metastatic PDAC models. This is the first study of its kind combining SBRT with IL-12mRNA and provides a promising new approach for treating this aggressive malignancy.

Local Delivery of SBRT and IL12 by mRNA Technology Overcomes Immunosuppressive Barriers to Eliminate Pancreatic Cancer.

The immunosuppressive milieu in pancreatic cancer (PC) is a significant hurdle to treatments, resulting in survival statistics that have barely changed in 5 decades. Here we present a combination treatment consisting of stereotactic body radiation therapy (SBRT) and IL-12 mRNA lipid nanoparticles delivered directly to pancreatic murine tumors. This treatment was effective against primary and metastatic models, achieving cures in both settings. IL-12 protein concentrations were transient and localized primarily to the tumor. Depleting CD4 and CD8 T cells abrogated treatment efficacy, confirming they were essential to treatment response. Single cell RNA sequencing from SBRT/IL-12 mRNA treated tumors demonstrated not only a complete loss of T cell exhaustion, but also an abundance of highly proliferative and effector T cell subtypes. SBRT elicited T cell receptor clonal expansion, whereas IL-12 licensed these cells with effector function. This is the first report demonstrating the utility of SBRT and IL-12 mRNA in PC. Statement of significance: This study demonstrates the use of a novel combination treatment consisting of radiation and immunotherapy in murine pancreatic tumors. This treatment could effectively treat local and metastatic disease, suggesting it may have the potential to treat a cancer that has not seen a meaningful increase in survival in 5 decades.

Histologic effects of autologous platelet gel in skin flap healing.

OBJECTIVE: To supply animal model data in the area of autologous platelet gel (APG) in the application of plastic and reconstructive surgical procedures in which clinical observation purports augmented hemostasis and optimal wound healing. METHODS: Paired skin flaps were dissected on each side of the backs of 12 New Zealand white rabbits. Prior to suture closure, APG was placed in the wound bed on 1 side (hereinafter, APG wounds), and the wound bed on the other side served as a control. Punch biopsy specimens from each wound were obtained at 1-, 2-, and 3-week intervals and examined by a blinded pathologist. RESULTS: Histologic analysis revealed increased overall inflammation in the APG wounds, which was significant at week 3 (P = .05). The APG wounds also demonstrated significant increases in subdermal eosinophilia across the study period (P = .01). Neutrophilic and monocytic inflammation both increased over the time interval studied, but neither variable exhibited differences between control and APG wounds. No significant differences were observed in the degree of fibrosis or collagen deposition between the types of wounds. CONCLUSIONS: The APG wounds demonstrated increased inflammation and tissue eosinophilia compared with the control wounds. These findings underscore the observation that concentrated platelets, although autologous, have a definite effect on postsurgical inflammation in a rabbit model.

Cancer of the paranasal sinuses.

Carcinoma of the paranasal sinuses is a heterogeneous disease that is frequently locally advanced at presentation. Treatment commonly includes radical surgery followed by adjuvant therapy. Despite such aggressive therapy, the likelihood of locoregional failure is significant, resulting in poor survival, particularly with advanced tumors. In this paper, we review the recent literature in search of advances in treatment optimization. These advances include conformal radiotherapy techniques, chemotherapy, image-guided and endoscopic surgery, and surgical approaches for orbital preservation, all of which have a potential to improve the oncologic outcome as well as cosmetic and functional results. We also outline our approach in using these advances in the management of patients with these cancers.