Increased Abundance of Tumour-Associated Neutrophils in HPV-Negative Compared to HPV-Positive Oropharyngeal Squamous Cell Carcinoma Is Mediated by IL-1R Signalling

Abstract

The incidence of human papillomavirus (HPV)-associated cancer is increasing and HPV is now implicated in the aetiology of more than 60% of all oropharyngeal squamous cell carcinomas (OPSCC). In OPSCC, innate immune cells such as neutrophils and macrophages generally correlate with poor prognosis, whilst adaptive immune cells, such as lymphocytes, tend to correlate with improved prognosis. This may, in part, be due to differences in the immune response within the tumour microenvironment leading to the recruitment of specific tumour-associated leukocyte sub-populations. In this study, we aimed to examine if differences exist in the levels of infiltrated leukocyte sub-populations, with particular emphasis on tumour-associated neutrophils (TAN), and to determine the mechanism of chemokine-induced leukocyte recruitment in HPV-positive compared to HPV-negative OPSCC. Immunohistochemical analysis showed that HPV-negative OPSCC contained significantly more neutrophils than HPV-positive tumours, whilst levels of CD68+ macrophages and CD3+ lymphocytes were similar. Using a 3D tissue culture model to represent tumour-stromal interactions, we demonstrated that HPV-negative tumour-stromal co-cultures expressed significantly higher levels of CXCL8, leading to increased neutrophil recruitment compared to their HPV-positive counterparts. HPV-negative OPSCC cells have previously been shown to express higher levels of IL-1 than their HPV-positive counterparts, indicating that this cytokine may be responsible for driving increased chemokine production in the HPV-negative 3D model. Inhibition of IL-1R in the tumour-stromal models using the receptor-specific antagonist, anakinra, dramatically reduced chemokine secretion and significantly impaired neutrophil and monocyte recruitment, suggesting that this tumour-stromal response is mediated by the IL-1/IL-1R axis. Here, we identify a mechanism by which HPV-negative OPSCC may recruit more TAN than HPV-positive OPSCC. Since TAN are associated with poor prognosis in OPSCC, our study identifies potential therapeutic targets aimed at redressing the chemokine imbalance to reduce innate immune cell infiltration with the aim of improving patient outcome.

IL-1/IL-1R Signaling in Head and Neck Cancer

“…Interaction of IL-1β with the TME leads to monocyte recruitment that then differentiate into tumor-associated macrophages (TAMs) whose increased levels in HNSCC are associated with poor prognosis [ 12 , 117 ]. Also, stimulates the production of numerous cytokines by different cell types, such [ 116 ] as cancer-associated fibroblasts (CAFs), normal fibroblast, endothelial cells, neutrophils as well as oral dysplastic and cancer cells, among others [ 10 , 11 , 98 , 118 ], through an IL-1-dependent innate immune response.…”

“…This creates an inflammatory TME that can predispose to tumor progression [ 121 ] ( Figure 1 ). For example, in HNSCC IL-1 signaling drives neutrophil and monocyte recruitment [ 10 ], and accumulation of these tumor-associated leukocytes has been associated with poor prognosis [ 13 , 122 ]. The IL-1/IL-1R axis mediates chemokine release from normal tonsillar fibroblasts (NTF) induced by HPV-negative oropharyngeal carcinoma (OPC) cells, which can be reverted with IL-1 inhibition [ 11 ].…”

“…Interleukin-1 (IL-1) is commonly found at tumor sites and is considered one of the most important cytokines of the TME, where it plays a key role in carcinogenesis and tumor progression [ 6 ], and its expression has been associated with poor prognosis in cancer patients [ 7 ]. There is a growing association linking head and neck squamous cell carcinoma (HNSCC) with chronic inflammation [ 8 , 9 ], in which IL-1/IL-1R signaling seems to be a key player [ 10 ]. Cumulating evidence suggests that the effects of IL-1 autocrine and paracrine signaling within the TME is central to HNSCC development.…”

Systematic analysis of IL-1 cytokine signaling by high-risk HPV oncoproteins

“…However, not all immune cell populations are enriched in HPV-positive tumors. Al-Sahaf and colleagues determined that HPV-negative tumors contain more neutrophils and express more of the neutrophil chemoattractant CXCL8 compared to HPV-positive tumors (15, 29). Overall, it is apparent that immune cell recruitment differs in HPV-positive vs HPV-negative tumors and that chronic inflammation could contribute to HPV-mediated carcinogenesis (30, 31).…”

IL-1RAP, a Key Therapeutic Target in Cancer

“…Thirdly, in HPV-negative oropharyngeal squamous cell carcinoma (OPSCC), it has been demonstrated that the IL-1/IL-1R axis is responsible for the production of the chemokine CXCL8, which will recruit neutrophil cells to the TME. These tumor-associated neutrophil cells (TAN) are associated with poor prognosis in OPSCC [ 138 ].…”