Unleashing Natural IL18 Activity Using an Anti-IL18BP Blocker Induces Potent Immune Stimulation and Antitumor Effects.

Recombinant cytokines have limited anticancer efficacy mostly due to a narrow therapeutic window and systemic adverse effects. IL18 is an inflammasome-induced proinflammatory cytokine, which enhances T- and NK-cell activity and stimulates IFNγ production. The activity of IL18 is naturally blocked by a high-affinity endogenous binding protein (IL18BP). IL18BP is induced in the tumor microenvironment (TME) in response to IFNγ upregulation in a negative feedback mechanism. In this study, we found that IL18 is upregulated in the TME compared with the periphery across multiple human tumors and most of it is bound to IL18BP. Bound IL18 levels were largely above the amount required for T-cell activation in vitro, implying that releasing IL18 in the TME could lead to potent T-cell activation. To restore the activity of endogenous IL18, we generated COM503, a high-affinity anti-IL18BP that blocks the IL18BP:IL18 interaction and displaces precomplexed IL18, thereby enhancing T- and NK-cell activation. In vivo, administration of a surrogate anti-IL18BP, either alone or in combination with anti-PD-L1, resulted in significant tumor growth inhibition and increased survival across multiple mouse tumor models. Moreover, the anti-IL18BP induced pronounced TME-localized immune modulation including an increase in polyfunctional nonexhausted T- and NK-cell numbers and activation. In contrast, no increase in inflammatory cytokines and lymphocyte numbers or activation state was observed in serum and spleen. Taken together, blocking IL18BP using an Ab is a promising approach to harness cytokine biology for the treatment of cancer.

Targeted nanoparticles modify neutrophil function in vivo.

Neutrophils play critical roles in a broad spectrum of clinical conditions. Accordingly, manipulation of neutrophil function may provide a powerful immunotherapeutic approach. However, due to neutrophils characteristic short half-life and their large population number, this possibility was considered impractical. Here we describe the identification of peptides which specifically bind either murine or human neutrophils. Although the murine and human neutrophil-specific peptides are not cross-reactive, we identified CD177 as the neutrophil-expressed binding partner in both species. Decorating nanoparticles with a neutrophil-specific peptide confers neutrophil specificity and these neutrophil-specific nanoparticles accumulate in sites of inflammation. Significantly, we demonstrate that encapsulating neutrophil modifying small molecules within these nanoparticles yields specific modulation of neutrophil function (ROS production, degranulation, polarization), intracellular signaling and longevity both in vitro and in vivo. Collectively, our findings demonstrate that neutrophil specific targeting may serve as a novel mode of immunotherapy in disease.

Immature Low-Density Neutrophils Exhibit Metabolic Flexibility that Facilitates Breast Cancer Liver Metastasis.

Neutrophils are phenotypically heterogeneous and exert either anti- or pro-metastatic functions. We show that cancer-cell-derived G-CSF is necessary, but not sufficient, to mobilize immature low-density neutrophils (iLDNs) that promote liver metastasis. In contrast, mature high-density neutrophils inhibit the formation of liver metastases. Transcriptomic and metabolomic analyses of high- and low-density neutrophils reveal engagement of numerous metabolic pathways specifically in low-density neutrophils. iLDNs exhibit enhanced global bioenergetic capacity, through their ability to engage mitochondrial-dependent ATP production, and remain capable of executing pro-metastatic neutrophil functions, including NETosis, under nutrient-deprived conditions. We demonstrate that NETosis is an important neutrophil function that promotes breast cancer liver metastasis. iLDNs rely on the catabolism of glutamate and proline to support mitochondrial-dependent metabolism in the absence of glucose, which enables sustained NETosis. These data reveal that distinct pro-metastatic neutrophil populations exhibit a high degree of metabolic flexibility, which facilitates the formation of liver metastases.

Hyperglycemia Impairs Neutrophil Mobilization Leading to Enhanced Metastatic Seeding.

Preexisting diabetes is a risk factor for the development of multiple types of cancer. Additionally, diabetic patients face a poorer prognosis when diagnosed with cancer. To gain insight into the effects of hyperglycemia, a hallmark of diabetes, on tumor growth and metastatic progression, we combined mouse models of cancer and hyperglycemia. We show that while hyperglycemia attenuates primary tumor growth, it concomitantly increases metastatic seeding in a distant organ. We further show that the increase in metastatic seeding is due to impaired secretion of granulocyte colony-stimulating factor (G-CSF) and impaired neutrophil mobilization. Normalizing blood glucose levels using insulin rescues neutrophil recruitment and tumor growth and concomitantly reduces metastatic seeding. These results provide links among hyperglycemia-induced changes in neutrophil mobilization, primary tumor growth, and metastatic progression. Furthermore, our observations highlight the importance of normalizing blood glucose levels in hyperglycemic cancer patients.

Always Look On the Bright Side: Anti-Tumor Functions of Neutrophils.

Neutrophils are the most abundant population of white blood cells in the human circulation playing a critical role in inflammation and in host defense against microbial infections. In recent years there has been growing interest in understanding the role the tumor microenvironment plays in tumor growth and progression. In this context, the role neutrophils play has been a matter of debate as neutrophils were shown to possess both tumor promoting and tumor limiting properties. These conflicting observations stem from differences in how neutrophils respond to environmental cues as well as from the existence of distinct tumor-promoting and tumor-limiting neutrophil populations. Here, we review general aspects of neutrophil biology and the favorable functions of neutrophils in the primary tumor and the pre-metastatic microenvironment. We further discuss the mechanisms neutrophils employ to limit tumor progression and highlight the aspects of neutrophil biology that may be targeted in future neutrophil-based cancer immunotherapies.

Prox1 Is Required for Oligodendrocyte Cell Identity in Adult Neural Stem Cells of the Subventricular Zone.

Adult neural stem cells with the ability to generate neurons and glia cells are active throughout life in both the dentate gyrus (DG) and the subventricular zone (SVZ). Differentiation of adult neural stem cells is induced by cell fate determinants like the transcription factor Prox1. Evidence has been provided for a function of Prox1 as an inducer of neuronal differentiation within the DG. We now show that within the SVZ Prox1 induces differentiation into oligodendrocytes. Moreover, we find that loss of Prox1 expression in vivo reduces cell migration into the corpus callosum, where the few Prox1 deficient SVZ-derived remaining cells fail to differentiate into oligodendrocytes. Thus, our work uncovers a novel function of Prox1 as a fate determinant for oligodendrocytes in the adult mammalian brain. These data indicate that the neurogenic and oligodendrogliogenic lineages in the two adult neurogenic niches exhibit a distinct requirement for Prox1, being important for neurogenesis in the DG but being indispensable for oligodendrogliogenesis in the SVZ. Stem Cells 2016;34:2115-2129.