The impact of tumor immunogenicity on cancer pain phenotype using syngeneic oral cancer mouse models

Combination of proton- or X-irradiation with anti-PDL1 immunotherapy in two murine oral cancers

Combining radiation therapy with immunotherapy is a strategy to improve both treatments. The purpose of this study was to compare responses for two syngeneic head and neck cancer (HNC) tumor models in mice following X-ray or proton irradiation with or without immune checkpoint inhibition (ICI). MOC1 (immunogenic) and MOC2 (less immunogenic) tumors were inoculated in the right hind leg of each mouse (C57BL/6J, n = 398). Mice were injected with anti-PDL1 (10 mg/kg, twice weekly for 2 weeks), and tumors were treated with single-dose irradiation (5-30 Gy) with X-rays or protons. MOC2 tumors grew faster and were more radioresistant than MOC1 tumors, and all mice with MOC2 tumors developed metastases. Irradiation reduced the tumor volume in a dose-dependent manner. ICI alone reduced the tumor volume for MOC1 with 20% compared to controls, while no reduction was seen for MOC2. For MOC1, there was a clear treatment synergy when combining irradiation with ICI for radiation doses above 5 Gy and there was a tendency for X-rays being slightly more biologically effective compared to protons. For MOC2, there was a tendency of protons being more effective than X-rays, but both radiation types showed a small synergy when combined with ICI. Although the responses and magnitudes of the therapeutic effect varied, the optimal radiation dose for maximal synergy appeared to be in the order of 10-15 Gy, regardless of tumor model.

HPV+ head and neck cancer-derived small extracellular vesicles communicate with TRPV1+ neurons to mediate cancer pain

ABSTRACT

Severe pain is often experienced by patients with head and neck cancer and is associated with a poor prognosis. Despite its frequency and severity, current treatments fail to adequately control cancer-associated pain because of our lack of mechanistic understanding. Although recent works have shed some light of the biology underlying pain in HPV-negative oral cancers, the mechanisms mediating pain in HPV+ cancers remain unknown. Cancer-derived small extracellular vesicles (cancer-sEVs) are well positioned to function as mediators of communication between cancer cells and neurons. Inhibition of cancer-sEV release attenuated pain in tumor-bearing mice. Injection of purified cancer-sEVs is sufficient to induce pain hypersensitivity in naive mice that is prevented by QX-314 treatment and in Trpv1-/- mice. Cancer-sEVs triggered calcium influx in nociceptors, and inhibition or ablation of nociceptors protects against cancer pain. Interrogation of published sequencing data of human sensory neurons exposed to human cancer-sEVs suggested a stimulation of protein translation in neurons. Induction of translation by cancer-sEVs was validated in our mouse model, and its inhibition alleviated cancer pain in mice. In summary, our work reveals that HPV+ head and neck squamous cell carcinoma-derived sEVs alter TRPV1+ neurons by promoting nascent translation to mediate cancer pain and identified several promising therapeutic targets to interfere with this pathway.

From pain to tumor immunity: influence of peripheral sensory neurons in cancer

The nervous and immune systems are the primary sensory interfaces of the body, allowing it to recognize, process, and respond to various stimuli from both the external and internal environment. These systems work in concert through various mechanisms of neuro-immune crosstalk to detect threats, provide defense against pathogens, and maintain or restore homeostasis, but can also contribute to the development of diseases. Among peripheral sensory neurons (PSNs), nociceptive PSNs are of particular interest. They possess a remarkable capability to detect noxious stimuli in the periphery and transmit this information to the brain, resulting in the perception of pain and the activation of adaptive responses. Pain is an early symptom of cancer, often leading to its diagnosis, but it is also a major source of distress for patients as the disease progresses. In this review, we aim to provide an overview of the mechanisms within tumors that are likely to induce cancer pain, exploring a range of factors from etiological elements to cellular and molecular mediators. In addition to transmitting sensory information to the central nervous system, PSNs are also capable, when activated, to produce and release neuropeptides (e.g., CGRP and SP) from their peripheral terminals. These neuropeptides have been shown to modulate immunity in cases of inflammation, infection, and cancer. PSNs, often found within solid tumors, are likely to play a significant role in the tumor microenvironment, potentially influencing both tumor growth and anti-tumor immune responses. In this review, we discuss the current state of knowledge about the degree of sensory innervation in tumors. We also seek to understand whether and how PSNs may influence the tumor growth and associated anti-tumor immunity in different mouse models of cancer. Finally, we discuss the extent to which the tumor is able to influence the development and functions of the PSNs that innervate it.

Sex as a Biological Variable in Oral Diseases: Evidence and Future Prospects

The interest of the scientific community on sex and gender differences in health and disease has increased substantially over the past 25 to 30 y as a result of a long process of events and policies in the biomedical field. This is crucial as compelling evidence from human and animal model studies has demonstrated that sex and gender influence health, molecular and cellular processes, and response and predisposition to disease. The present scoping review aims to provide a synthesis of sex differences in oral diseases, ranging from periodontal disease to orofacial pain conditions, from risk of caries development to apical periodontitis. Overall, findings from this review further support a role for sexual dimorphism influencing disease predisposition and/or progression in oral diseases. Of note, this review also highlights the lack of consideration of additional factors such as gender and other psychosocial and external factors potentially influencing oral health and disease. New conceptual frameworks capable of capturing multiple fundamental domains and measurements should be developed in clinical and preclinical studies to inform sex-based individualized preventive and treatment strategies.

Sex-dependent differences in the genomic profile of lingual sensory neurons in naïve and tongue-tumor bearing mice

Mechanisms of sex-dependent orofacial pain are widely understudied. A significant gap in knowledge exists about comprehensive regulation of tissue-specific trigeminal sensory neurons in diseased state of both sexes. Using RNA sequencing of FACS sorted retro-labeled sensory neurons innervating tongue tissue, we determined changes in transcriptomic profiles in males and female mice under naïve as well as tongue-tumor bearing conditions Our data revealed the following interesting findings: (1) FACS sorting obtained higher number of neurons from female trigeminal ganglia (TG) compared to males; (2) Naïve female neurons innervating the tongue expressed immune cell markers such as Csf1R, C1qa and others, that weren't expressed in males. This was validated by Immunohistochemistry. (3) Accordingly, immune cell markers such as Csf1 exclusively sensitized TRPV1 responses in female TG neurons. (4) Male neurons were more tightly regulated than female neurons upon tumor growth and very few differentially expressed genes (DEGs) overlapped between the sexes, (5) Male DEGs contained higher number of transcription factors whereas female DEGs contained higher number of enzymes, cytokines and chemokines. Collectively, this is the first study to characterize the effect of sex as well as of tongue-tumor on global gene expression, pathways and molecular function of tongue-innervating sensory neurons.

Lingual innervation in male and female marmosets

Several gaps in knowledge exists in our understanding of orofacial pain. Some of these include type of peripheral sensory innervation in specific tissues, differences in innervation between sexes and validation of rodent studies in higher order species. The current study addresses these gaps by validating mouse studies for sensory innervation of tongue tissue in non-human primates as well as assesses sex-specific differences. Tongue and trigeminal ganglia were collected from naïve male and female marmosets and tested for nerve fibers using specific markers by immunohistochemistry and number of fibers quantified. We also tested whether specific subgroups of nerve fibers belonged to myelinating or non-myelinating axons. We observed that similar to findings in mice, marmoset tongue was innervated with nerve filaments expressing nociceptor markers like CGRP and TRPV1 as well as non-nociceptor markers like TrkB, parvalbumin (PV) and tyrosine hydroxylase (TH). Furthermore, we found that while portion of TrkB and PV may be sensory fibers, TH-positive fibers were primarily sympathetic nerve fibers. Moreover, number of CGRP, TrkB and TH-positive nerve fibers were similar in both sexes. However, we observed a higher proportion of myelinated TRPV1 positive fibers in females than in males as well as increased number of PV + fibers in females. Taken together, the study for the first time characterizes sensory innervation in non-human primates as well as evaluates sex-differences in innervation of tongue tissue, thereby laying the foundation for future orofacial pain research with new world smaller NHPs like the common marmoset.

Preclinical orofacial pain assays and measures and chronic primary orofacial pain research: where we are and where we need to go

Chronic primary orofacial pain (OFP) conditions such as painful temporomandibular disorders (pTMDs; i.e., myofascial pain and arthralgia), idiopathic trigeminal neuralgia (TN), and burning mouth syndrome (BMS) are seemingly idiopathic, but evidence support complex and multifactorial etiology and pathophysiology. Important fragments of this complex array of factors have been identified over the years largely with the help of preclinical studies. However, findings have yet to translate into better pain care for chronic OFP patients. The need to develop preclinical assays that better simulate the etiology, pathophysiology, and clinical symptoms of OFP patients and to assess OFP measures consistent with their clinical symptoms is a challenge that needs to be overcome to support this translation process. In this review, we describe rodent assays and OFP pain measures that can be used in support of chronic primary OFP research, in specific pTMDs, TN, and BMS. We discuss their suitability and limitations considering the current knowledge of the etiology and pathophysiology of these conditions and suggest possible future directions. Our goal is to foster the development of innovative animal models with greater translatability and potential to lead to better care for patients living with chronic primary OFP.

Sex-dependent Differences in the Genomic Profile of Lingual Sensory Neurons in Naïve and Tongue-Tumor Bearing Mice

Mechanisms of sex-dependent orofacial pain are widely understudied. A significant gap in knowledge exists about comprehensive regulation of tissue-specific trigeminal sensory neurons in diseased state of both sexes. Using RNA sequencing of FACS sorted retro-labeled sensory neurons innervating tongue tissue, we determined changes in transcriptomic profiles in males and female mice under naïve as well as tongue-tumor bearing conditions Our data revealed the following interesting findings: 1) Tongue tissue of female mice was innervated with higher number of trigeminal neurons compared to males; 2) Naïve female neurons innervating the tongue exclusively expressed immune cell markers such as Csf1R, C1qa and others, that weren't expressed in males. This was validated by Immunohistochemistry. 4) Accordingly, immune cell markers such as Csf1 exclusively sensitized TRPV1 responses in female TG neurons. 3) Male neurons were more tightly regulated than female neurons upon tumor growth and very few differentially expressed genes (DEGs) overlapped between the sexes, 5) Male DEGs contained higher number of transcription factors whereas female DEGs contained higher number of enzymes, cytokines and chemokines. Collectively, this is the first study to characterize the effect of sex as well as of tongue-tumor on global gene expression, pathways and molecular function of tongue-innervating sensory neurons.

A pilot study to improve pain phenotyping in head and neck cancer patients

Pain associated with head and neck cancer (HNC) is difficult to manage and reduces quality of life. It has been increasingly recognized that HNC patients exhibit a wide range of pain symptoms. Here we developed an orofacial pain assessment questionnaire and conducted a pilot study to improve pain phenotyping in HNC patients at the diagnosis. The questionnaire captures the following pain characteristics: pain intensity, location, quality, duration, and frequency; the impact of pain on daily activities; changes in smell and food sensitivities. Twenty-five HNC patients completed the questionnaire. 88% patients reported pain at the site of tumor; 36% reported multiple pain sites. All patients with pain reported at least one neuropathic pain (NP) descriptor, 54.5% reported at least two NP descriptors. The most common descriptors were "burning" and "pins and needles". Most patients reported increased pain to sour or hot/spicy food/drinks, and to food with coarse/hard textures. Patients exhibited impaired oral function, especially chewing, talking, mouth/jaw opening, and eating. Tumor progression has a significant impact on pain. Nodal metastasis is linked to pain at multiple body sites. Patients with advanced tumor staging experience greater pain at the primary tumor site, when exposed to hot or spicy food/drinks or food with hard/coarse texture, or when eating or chewing. We conclude that HNC patients experience a wide range of pain symptoms with altered mechanical, chemical, and temperature sensation. Improved phenotyping and stratification of pain in HNC patients will help address the underlying etiology, which may enable personalized therapeutic approaches in the future.