Smoothing T cell roads to the tumor: Chemokine post-translational regulation

Co-delivery of RNAi and chemokine by polyarginine nanocapsules enables the modulation of myeloid-derived suppressor cells

Myeloid-Derived Suppressor Cells (MDSCs), immunosuppressive cells that promote tumor growth, represent an attractive target in cancer immunotherapy. However, the clinical success of this strategy is limited by the lack of efficient drug delivery vehicles targeting this cell compartment. The objective of this work was to develop a delivery carrier, multilayer polymer nanocapsules, with the capacity to co-encapsulate two types of immunomodulatory drugs, a chemokine and an RNAi sequence, aimed at reverting MDSC-mediated immunosuppression. The chemokine CCL2, intended to attract monocyte-macrophage MDSCs, was encapsulated within the L2 inverse micellar aqueous domains of the lipid core of these nanocapsules. On the other hand, two different RNAi sequences that modulate the CCAAT/enhancer-binding protein beta (C/EBPβ) pathway, shC/EBPβ and miR 142-3p, were successfully associated to their polymer shell. These RNAi sequences were covered by subsequent layers of polyarginine and hyaluronic acid, thereby creating multi-layered assemblies that protected them and facilitated their targeted delivery. The in vitro studies performed in primary MDSCs cultures showed the capacity of miR 142-3p-loaded nanocapsules to reduce the highly immunosuppressive monocyte-macrophage subset. Additionally, the encapsulation of CCL2 within the nanocapsules induced a potent monocyte-macrophage chemoattraction that could be used to direct the therapy to these cell subsets. Finally, in vitro and in vivo studies showed the capacity of shC/EBPβ-loaded nanocapsules to downregulate C/EBPβ levels in MDSCs and to reduce monocyte differentiation into tumor-associated macrophages in an MCA-203 fibrosarcoma mice model. In conclusion, the multilayer polymer nanocapsules described here are efficient vehicles for the co-delivery of proteins and RNA, and are potential candidates as nanomedicines for the modulation of MDSCs.

Tadalafil reduces myeloid-derived suppressor cells and regulatory T cells and promotes tumor immunity in patients with head and neck squamous cell carcinoma

PURPOSE

Myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg) play a key role in the progression of head and neck squamous cell carcinoma (HNSCC). On the basis of our preclinical data demonstrating that phosphodiesterase-5 (PDE5) inhibition can modulate these cell populations, we evaluated whether the PDE5 inhibitor tadalafil can revert tumor-induced immunosuppression and promote tumor immunity in patients with HNSCC.

EXPERIMENTAL DESIGN

First, we functionally and phenotypically characterized MDSCs in HNSCCs and determined, retrospectively, whether their presence at the tumor site correlates with recurrence. Then, we performed a prospective single-center, double-blinded, randomized, three-arm study in which patients with HNSCC undergoing definitive surgical resection of oral and oropharyngeal tumors were treated with tadalafil 10 mg/day, 20 mg/day, or placebo for at least 20 days preoperatively. Blood and tumor MDSC and Treg presence and CD8(+) T-cell reactivity to tumor antigens were evaluated before and after treatment.

RESULTS

MDSCs were characterized in HNSCC and their intratumoral presence significantly correlates with recurrence. Tadalafil treatment was well tolerated and significantly reduced both MDSCs and Treg concentrations in the blood and in the tumor (P < 0.05). In addition, the concentration of blood CD8(+) T cells reactive to autologous tumor antigens significantly increased after treatment (P < 0.05). Tadalafil immunomodulatory activity was maximized at an intermediate dose but not at higher doses. Mechanistic analysis suggests a possible off-target effect on PDE11 at high dosages that, by increasing intracellular cAMP, may negatively affect antitumor immunity.

CONCLUSIONS

Tadalafil seems to beneficially modulate the tumor micro- and macro-environment in patients with HNSCC by lowering MDSCs and Tregs and increasing tumor-specific CD8(+) T cells in a dose-dependent fashion.

The immune system and head and neck squamous cell carcinoma: from carcinogenesis to new therapeutic opportunities

Head and neck squamous cell carcinomas (HNSCCs) exhibit complex interactions with the host immune system that may simultaneously explain resistance to various therapeutic modalities and that may also provide opportunities for therapeutic intervention. Discoveries in immunologic research over the last decade have led to an increased understanding of these interactions as well as the development of a multitude of investigational immunotherapies. Here, we describe the interaction between HNSCC and the immune system, including a discussion of immune cells involved with tumor carcinogenesis and the role of immune-modulating factors derived from tumors. We also describe the current immunotherapeutic approaches being investigated for HNSCC, including a discussion of the successes and limitations. With this review, we hope to present HNSCC as a model to guide future research in cancer immunology.

The emerging role of soluble HLA-G in the control of chemotaxis

HLA-G is an immunosuppressive molecule, that impairs the function of different immune cell populations, both in physiological and pathological conditions. Here, we have analyzed data obtained by our group and others regarding sHLA-G concentration in plasma from patients with different diseases. Next, we have summarized novel data regarding the impairment of chemotaxis of different immune effector cells mediated by sHLA-G. Finally, we have discussed the impact of this function on the immune response during cancer, viral infection, autoimmunity, and on B cell differentiation in secondary lymphoid organs. In conclusion, we have delineated a role of sHLA-G in the control of chemotaxis of immune effector cells, that may be relevant to modulate immune responses in different settings.