Cara D. Carey

Genetic Vaccines To Potentiate the Effective CD103+ Dendritic Cell–Mediated Cross-Priming of Antitumor Immunity

The development of effective cancer vaccines remains an urgent, but as yet unmet, clinical need. This deficiency is in part due to an incomplete understanding of how to best invoke dendritic cells (DC) that are crucial for the induction of tumor-specific CD8+ T cells capable of mediating durable protective immunity. In this regard, elevated expression of the transcription factor X box–binding protein 1 (XBP1) in DC appears to play a decisive role in promoting the ability of DC to cross-present Ags to CD8+ T cells in the therapeutic setting. Delivery of DNA vaccines encoding XBP1 and tumor Ag to skin DC resulted in increased IFN-α production by plasmacytoid DC (pDC) from skin/tumor draining lymph nodes and the cross-priming of Ag-specific CD8+ T cell responses associated with therapeutic benefit. Antitumor protection was dependent on cross-presenting Batf3+ DC, pDC, and CD8+ T cells. CD103+ DC from the skin/tumor draining lymph nodes of the immunized mice appeared responsible for activation of Ag-specific naive CD8+ T cells, but were dependent on pDC for optimal effectiveness. Similarly, human XBP1 improved the capacity of human blood- and skin-derived DC to activate human T cells. These data support an important intrinsic role for XBP1 in DC for effective cross-priming and orchestration of Batf3+ DC–pDC interactions, thereby enabling effective vaccine induction of protective antitumor immunity.

Electrophilic nitro-fatty acids suppress allergic contact dermatitis in mice.

Reactions between nitric oxide (NO), nitrite ( NO2− ), and unsaturated fatty acids give rise to electrophilic nitro‐fatty acids (NO2‐FAs), such as nitro oleic acid (OA‐NO2) and nitro linoleic acid (LNO2). Endogenous electrophilic fatty acids (EFAs) mediate anti‐inflammatory responses by modulating metabolic and inflammatory signal transduction reactions. Hence, there is considerable interest in employing NO2‐FAs and other EFAs for the prevention and treatment of inflammatory disorders. Thus, we sought to determine whether OA‐NO2, an exemplary nitro‐fatty acid, has the capacity to inhibit cutaneous inflammation.

Extracellular ATP and IL-23 Form a Local Inflammatory Circuit Leading to the Development of a Neutrophil-Dependent Psoriasiform Dermatitis

Psoriasis is a chronic inflammatory skin disease dependent on the IL-23/IL-17 axis, a potent inflammatory pathway involved in pathogen clearance and autoimmunity. Several triggers have been proposed as initiators for psoriasis, including alarmins such as adenosine triphosphate. However, the role of alarmins in psoriasis pathogenesis and cutaneous inflammation has not been well addressed. Studies show that signaling through the P2X7 receptor (P2X7R) pathway underlies the development of psoriasiform inflammation. In this regard, psoriasiform dermatitis induced by IL-23 is dependent on P2X7R signaling. Furthermore, direct activation of the P2X7R is sufficient to induce a well-characterized psoriasiform dermatitis. Mechanistic studies determined that P2X7R-induced inflammation is largely dependent on the IL-1β/NLRP3 inflammasome pathway and neutrophils. In conclusion, this work provides basic mechanistic insight into local inflammatory circuits induced after purinergic P2X7R signaling that are likely involved in the pathogenesis of many inflammatory diseases, such as psoriasis.

Topical electrophilic nitro-fatty acids potentiate cutaneous inflammation

ABSTRACT Endogenous electrophilic fatty acids mediate anti‐inflammatory responses by modulating metabolic and inflammatory signal transduction and gene expression. Nitro‐fatty acids and other electrophilic fatty acids may thus be useful for the prevention and treatment of immune‐mediated diseases, including inflammatory skin disorders. In this regard, subcutaneous (SC) injections of nitro oleic acid (OA‐NO2), an exemplary nitro‐fatty acid, inhibit skin inflammation in a model of allergic contact dermatitis (ACD). Given the nitration of unsaturated fatty acids during metabolic and inflammatory processes and the growing use of fatty acids in topical formulations, we sought to further study the effect of nitro‐fatty acids on cutaneous inflammation. To accomplish this, the effect of topically applied OA‐NO2 on skin inflammation was evaluated using established murine models of contact hypersensitivity (CHS). In contrast to the effects of subcutaneously injected OA‐NO2, topical OA‐NO2 potentiated hapten‐dependent inflammation inducing a sustained neutrophil‐dependent inflammatory response characterized by psoriasiform histological features, increased angiogenesis, and an inflammatory infiltrate that included neutrophils, inflammatory monocytes, and &ggr;&dgr; T cells. Consistent with these results, HPLC‐MS/MS analysis of skin from psoriasis patients displayed a 56% increase in nitro‐conjugated linoleic acid (CLA‐NO2) levels in lesional skin compared to non‐lesional skin. These results suggest that nitro‐fatty acids in the skin microenvironment are products of cutaneous inflammatory responses and, in high local concentrations, may exacerbate inflammatory skin diseases. Graphical abstract Figure. No caption available. HighlightsOA‐NO2 applied to sites of cutaneous inflammation potentiates that inflammation.The inflammatory response induced by OA‐NO2 is dependent on neutrophils.Human psoriatic lesions have an increase in nitrated fatty acids.

Tumor-derived high-mobility group box 1 and thymic stromal lymphopoietin are involved in modulating dendritic cells to activate T regulatory cells in a mouse model

High-mobility group box 1 (HMGB1) is involved in the tumor-associated activation of regulatory T cells (Treg), but the mechanisms remain unknown. In a mouse tumor model, silencing HMGB1 in tumor cells or inhibiting tumor-derived HMGB1 not only dampened the capacity of tumor cells to produce thymic stromal lymphopoietin (TSLP), but also aborted the tumor-associated modulation of Treg-activating DC. Tumor-derived HMGB1 triggered the production of TSLP by tumor cells. Importantly, both tumor-derived HMGB1 and TSLP were necessary for modulating DC to activate Treg in a TSLP receptor (TSLPR)-dependent manner. In the therapeutic model, intratumorally inhibiting tumor-derived HMGB1 (causing downstream loss of TSLP production) attenuated Treg activation, unleashed tumor-specific CD8 T cell responses, and elicited CD8α+/CD103+DC- and T cell-dependent antitumor activity. These results suggest a new pathway for the activation of Treg involving in tumor-derived HMGB1 and TSLP, and have important implications for incorporating HMGB1 inhibitors into cancer immunotherapy.

Intratumoral delivery of tumor antigen-loaded DC and tumor-primed CD4+ T cells combined with agonist α-GITR mAb promotes durable CD8+ T-cell-dependent antitumor immunity

ABSTRACT The progressive tumor microenvironment (TME) coordinately supports tumor cell expansion and metastasis, while it antagonizes the survival and (poly-)functionality of antitumor T effector cells. There remains a clear need to develop novel therapeutic strategies that can transform the TME into a pro-inflammatory niche that recruits and sustains protective immune cell populations. While intravenous treatment with tumor-primed CD4+ T cells combined with intraperitoneal delivery of agonist anti-glucocorticoid-induced TNF receptor (α-GITR) mAb results in objective antitumor responses in murine early stage disease models, this approach is ineffective against more advanced tumors. Further subcutaneous co-administration of a vaccine consisting of tumor antigen-loaded dendritic cells (DC) failed to improve the antitumor efficacy of this approach. Remarkably, these same three therapeutic agents elicited significant antitumor benefits when the antitumor CD4+ T cells and tumor antigen-loaded DC were co-injected directly into tumors along with intratumoral or intraperitoneal delivery of α-GITR mAb. This latter protocol induced the production of an array of antitumor cytokines and chemokines within the TME, supporting increased tumor-infiltration by antitumor CD8+ T cells capable of mediating tumor regression and extended overall survival.

Abstract LB-225: Combination immunotherapy targeting HSP90 DNA-repair client proteins overexpressed in chemotherapy-resistant melanoma

DNA repair protein (DNA-RP) overexpression has been reported to involve post-translational protein stabilization mediated by the molecular chaperone heat shock protein 90(HSP90), thereby preventing proteasome-dependent degradation of these HSP90 “client” proteins. Overexpression of DNA-RP in a disease-stage associated manner has also been correlated to chemo resistance and poor overall prognosis. Hence, HSP90 inhibitors (HSP90i) have been heralded as co-therapy agents for cancer patients that have developed resistance to first-line treatments such as temozolomide (TMZ). In the presence of HSP90i, HSP90 client proteins rapidly become (poly)ubiquinated and undergo degradation resulting in the improved sensitization of cancer cells to chemo therapy. We observed that HSP90i promote the proteasome-dependent degradation of a broad range of DNA-repair client proteins. We have also identified 9 H-2Kb/Db-presented peptide epitopes derived from DNA-RPs that may be recognized by Type-1 CD8+ T cells after specific vaccination. When combined with adoptive cell therapy using DNA-RP-specific CD8+ T cells, HSP90i cotreatment yielded superior anti-tumor efficacy against established TMZ-resistant B16 tumors in C57BL/6 mice. Citation Format: Subhara Raveendran, Ronald Fecek, Cara Donahue Carey, Walter J. Storkus. Combination immunotherapy targeting HSP90 DNA-repair client proteins overexpressed in chemotherapy-resistant melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-225.