Paola Allavena

Tumour-associated macrophages as treatment targets in oncology

Macrophages are crucial drivers of tumour-promoting inflammation. Tumour-associated macrophages (TAMs) contribute to tumour progression at different levels: by promoting genetic instability, nurturing cancer stem cells, supporting metastasis, and taming protective adaptive immunity. TAMs can exert a dual, yin–yang influence on the effectiveness of cytoreductive therapies (chemotherapy and radiotherapy), either antagonizing the antitumour activity of these treatments by orchestrating a tumour-promoting, tissue-repair response or, instead, enhancing the overall antineoplastic effect. TAMs express molecular triggers of checkpoint proteins that regulate T-cell activation, and are targets of certain checkpoint-blockade immunotherapies. Other macrophage-centred approaches to anticancer therapy are under investigation, and include: inhibition of macrophage recruitment to, and/or survival in, tumours; functional re-education of TAMs to an antitumour, M1-like mode; and tumour-targeting monoclonal antibodies that elicit macrophage-mediated extracellular killing, or phagocytosis and intracellular destruction of cancer cells. The evidence supporting these strategies is reviewed herein. We surmise that TAMs can provide tools to tailor the use of cytoreductive therapies and immunotherapy in a personalized medicine approach, and that TAM-focused therapeutic strategies have the potential to complement and synergize with both chemotherapy and immunotherapy.

The interaction of anticancer therapies with tumor-associated macrophages

Mantovani and Allavena provide a comprehensive review on the effects of conventional anticancer therapies on tumor-associated macrophages.

Chemokines: A superfamily of chemotactic cytokines

Chemokines are a bipartite family of chemotactic proteins that bear the structural hallmark of four cysteine residues, the first two of which are in tandem. The spectrum of action of chemokines encompasses a large number of leukocyte populations, including monocytes, granulocytes, lymphocytes, NK and dendritic cells. Although the spectrum of action of chemokines largely overlaps, clear differences are still present. Chemokines play an important role in the recruitment of leukocytes at the site of inflammation, allergic reaction and tumors. Available information on receptor usage by MCP-1 and related chemokines and signal transduction pathways is reviewed. The better understanding of signaling mechanisms will provide a new basis for the development of therapeutic strategies.

Decidual natural killer cell tuning by autologous dendritic cells.

Problemu2002 Dendritic cells (DC)/natural killer (NK) cells interactions in the deciduas of early human pregnancies were analyzed in vitro.

Correlation of metabolic information on FDG-PET with tissue expression of immune markers in patients with non-small cell lung cancer (NSCLC) who are candidates for upfront surgery

PurposeEliciting antitumor T-cell response by targeting the PD-1/PD-L1 axis with checkpoint inhibitors has emerged as a novel therapeutic strategy in non-small cell lung cancer (NSCLC). The identification of predictors for sensitivity or resistance to these agents is, therefore, needed. Herein, we investigate the correlation of metabolic information on FDG-PET with tissue expression of immune-checkpoints and other markers of tumor-related immunity in resected NSCLC patients.Materials and methodsAll patients referred to our institution for upfront surgical resection of NSCLC, who were investigated with FDG-PET prior to surgery, were consecutively included in the study. From January 2010 to May 2014, 55 patients (stage IA-IIIB; M:Fu2009=u200942:13; mean age 68.9xa0years) were investigated. Sampled surgical tumor specimens were analyzed by immunohistochemistry (IHC) for CD68-TAMs (tumor-associated macrophages), CD8-TILs (tumor infiltrating lymphocytes), PD-1-TILs, and PD-L1 tumor expression. Immunoreactivity was evaluated, and scores were compared with imaging findings. FDG-PET images were analyzed to define semi-quantitative parameters: SUVmax and SUVmean. Metabolic information on FDG-PET was correlated with tissue markers expression and disease-free survival (DFS) considering a median follow-up of 16.2xa0months.ResultsThirty-six adenocarcinomas (ADC), 18 squamous cell carcinomas (SCC), and one sarcomatoid carcinoma were analyzed. All tumors resulted positive at FDG-PET: median SUVmax 11.3 (range: 2.3–32.5) and SUVmean 6.4 (range: 1.5–13) both resulted significantly higher in SCC compared to other NSCLC histotypes (pu2009=u20090.007 and 0.048, respectively). IHC demonstrated a median immunoreactive surface covered by CD68-TAMs of 5.41xa0% (range: 0.84–14.01xa0%), CD8-TILs of 2.9xa0% (range: 0.11–11.92xa0%), PD-1 of 0.65xa0% (range: 0.02–5.87xa0%), and PD-L1 of 0.7xa0% (range: 0.03–10.29xa0%). We found a statistically significant correlation between SUVmax and SUVmean with the expression of CD8 TILs (rhou2009=u20090.31; pu2009=u20090.027) and PD-1 (rhou2009=u20090.33; pu2009=u20090.017 and rhou2009=u20090.36; pu2009=u20090.009, respectively). The other tissue markers correlated as follows: CD8 TILs and PD-1 (rhou2009=u20090.45; pu2009=u20090.001), CD8 TILs and PD-L1 (rhou2009=u20090.41; pu2009=u20090.003), CD68-TAMs and PD-L1 (rhou2009=u20090.30; pu2009=u20090.027), PD-1 and PD-L1 (rhou2009=u20090.26; pu2009=u20090.059). With respect to patients’ outcome, SUVmax, SUVmean, and disease stage showed a statistically significant correlation with DFS (pu2009=u20090.002, 0.004, and <0.001, respectively).ConclusionsThe present study shows a direct association between metabolic parameters on FDG-PET and the expression of tumor-related immunity markers, suggesting a potential role for FDG-PET to characterize the tumor microenvironment and select NSCLC patients candidate to checkpoint inhibitors.

CHAPTER 15 – Dendritic cells and chemokines

Dendritic cells (DCs) respond to chemoattractants representative of different classes of chemotactic agonists, including lipid attractants, formyl peptides, and C5a generated by the complement cascade. Immature DCs, generated in vitro from monocytes, express a unique repertoire of inflammatory chemokine receptors. These receptors bind a pattern of “inflammatory” chemokines, including RANTES, MCP-3, MIP-1α, MIP-1β, and MIP-5. Langerhans cells (LCs) purified from skin or generated in vitro from CD34 precursors are characterized by the expression of CCR6, the receptor for MIP-3α, also known as LARC or exodus, in addition to the receptors expressed by monocyte DCs. The ability of precursor cells and immature DCs to migrate in response to a pattern of chemotactic signals is relevant for the accumulation of immature DCs into nonlymphoid tissues in normal conditions and during the early phase of inflammation, when local production of chemokines is strongly induced.

Differential role of Interleukin-1 and Interleukin-6 in K-Ras-driven pancreatic carcinoma undergoing mesenchymal transition

ABSTRACT K-Ras mutations are a hallmark of human pancreatic adenocarcinoma (PDAC) and epithelial-mesenchymal-transition (EMT) is a driver of progression. Oncogenic K-Ras causes the constitutive activation of NF-kB and the switch-on of an inflammatory program, which further fuels NF-kB and STAT3 activation. In this study we investigated how inflammatory pathways triggered by oncogenic K-Ras are regulated in human pancreatic cancer cells with distict epithelial or mesenchymal phenotype. Our results demonstrate that in cells with epithelial features, K-Ras driven inflammation is under the control of IL-1, while in cells undergoing EMT, is IL-1 independent. In pancreatic tumor cells with EMT phenotype, treatment with IL-1R antagonist (Anakinra) did not inhibit inflammatory cytokine production and tumor growth in mice. In these cells IL-6 is actively transcribed by the EMT transcription factor TWIST. Targeting of mesenchymal pancreatic tumors in vivo with anti-IL-6RmAb (RoActemra) successfully decreased tumor growth in immunodeficient mice, inhibited the inflammatory stroma and NF-kB-p65 and STAT3 phosphorylation in cancer cells. The results confirm that IL-1 is an important driver of inflammation in epithelial pancreatic tumors; however, tumor cells undergoing EMT will likely escape IL-1R inhibition, as IL-6 is continuously transcribed by TWIST. These findings have implications for the rational targeting of inflammatory pathways in human pancreatic cancer.

Non-redundant role of the chemokine receptor CX3CR1 in the anti-inflammatory function of gut macrophages.

Mucosal immunity at the intestinal level is constantly challenged by the presence of external food and microbial antigens and must be kept under strict control to avoid the rise of aberrant inflammation. Among cells of the innate immunity, macrophages expressing the chemokine receptor CX3CR1 are strategically located near the gut epithelial barrier. These cells contribute to the maintenance of homeostasis by producing the anti-inflammatory cytokine IL-10; however, their role in the control of full blown inflammation and tissue injury is controversial. In this study we investigated mice proficient or deficient for the expression of the CX3CR1 receptor in a model of dextran sulphate sodium (DSS) induced acute colitis. We found that KO mice (CX3CR1GFP/GFP) had a more severe disease compared to WT mice (CX3CR1GFP/+), both in terms of histological examination of colonic tissues and leukocyte infiltration, with an expansion of macrophages and CD4-Th17 lymphocytes. The expression of several inflammatory mediators (IL-1β, IL-6, IFNγ, iNOS) was also significantly upregulated in KO mice, despite higher IL-10 production. Overall, our study demonstrates that macrophages expressing a functional CX3CR1 receptor have an important and non-redundant role in controlling the abnormal intestinal inflammation that may lead to tissue damage.

Inflammatory and innate immune cells in cancer microenvironment and progression

It is established that persistent inflammation promotes tumor formation and disease progression. The inflammatory microenvironment within solid tumors is composed of soluble and cellular components, including several cytokines and chemokines, growth factors, enzymes, as well as host cells: endothelial cells, fibroblasts, and leukocytes. Tumor-associated myeloid cells (TAMC) represent the preponderant part of tumor-infiltrating leukocytes; they are a very heterogeneous entity of cells regulating diverse aspects of cancer biology. TAMC can directly support cancer growth and survival and regulate angiogenesis, metastasis, as well as immunosuppression. Accordingly, TAMC have recently become targets of new and innovative anticancer therapy approaches. This chapter will review the main characteristics of tumor-associated myeloid cells and their role in promoting tumor growth and dissemination. In addition, we will briefly address new therapeutic possibilities based on targeting of TAMC.

Tumors as a Paradigm for the In Vivo Role of Chemokines in Leukocyte Recruitment

Ever since the first description by Virchow in 1863, histopathologists have recognized the occurrence of host leukocytes in tumor tissues and/or at their periphery. Interestingly, Virchow felt that the frequent presence of a lymphoreticular infiltrate in human neoplasms reflected the origin of cancer at sites of previous chronic inflammation. In 1907 Hardley reported that normal cell infiltration in malignant melanoma indicated a “regressive process.” This observation marked a complete change in the general opinion as to the significance of the “lymphoreticular infiltrate,” a change reflected by a number of reports on pathology and prognosis. These opposite ways of looking at the relationship between leukocyte infiltration and malignancy have polarized views in the field but, indeed, reflect the pleiotropic, ambivalent functions of infiltrating cells.