Tumor-infiltrating nerves functionally alter brain circuits and modulate behavior in a male mouse model of head-and-neck cancer

Cancer patients often experience changes in mental health, prompting an exploration into whether nerves infiltrating tumors contribute to these alterations by impacting brain functions. Using a male mouse model for head and neck cancer, we utilized neuronal tracing techniques and show that tumor-infiltrating nerves indeed connect to distinct brain areas via the ipsilateral trigeminal ganglion. The activation of this neuronal circuitry led to behavioral alterations represented by decreased nest-building, increased latency to eat a cookie, and reduced wheel running. Tumor-infiltrating nociceptor neurons exhibited heightened activity, as indicated by increased calcium mobilization. Correspondingly, the specific brain regions receiving these neural projections showed elevated cFos and delta FosB expression in tumor-bearing mice, alongside markedly intensified calcium responses compared to non-tumor-bearing counterparts. The genetic elimination of nociceptor neurons in tumor-bearing mice led to decreased brain Fos expression and mitigated the behavioral alterations induced by the presence of the tumor. While analgesic treatment successfully restored behaviors involving oral movements to normalcy in tumor-bearing mice, it did not have a similar therapeutic effect on voluntary wheel running. This discrepancy points towards an intricate relationship, where pain is not the exclusive driver of such behavioral shifts. Unraveling the interaction between the tumor, infiltrating nerves, and the brain is pivotal to developing targeted interventions to alleviate the mental health burdens associated with cancer.

Functional neuronal circuits promote disease progression in cancer

The molecular and functional contributions of intratumoral nerves to disease remain largely unknown. We localized synaptic markers within tumors suggesting that these nerves form functional connections. Consistent with this, electrophysiological analysis shows that malignancies harbor significantly higher electrical activity than benign disease or normal tissues. We also demonstrate pharmacologic silencing of tumoral electrical activity. Tumors implanted in transgenic animals lacking nociceptor neurons show reduced electrical activity. These data suggest that intratumoral nerves remain functional at the tumor bed. Immunohistochemical staining demonstrates the presence of the neuropeptide, Substance P (SP), within the tumor space. We show that tumor cells express the SP receptor, NK1R, and that ligand/receptor engagement promotes cellular proliferation and migration. Our findings identify a mechanism whereby intratumoral nerves promote cancer progression.

Abstract A14: TRPV1+ sensory neurons provide a tumor supportive environment through recruitment of MDSCs

Cancer neuroscience has become an increasing area of focus in cancer research as our understanding of the presence and function of intra-tumoral neurons continues to emerge. Various publications indicate that tumor infiltrating neurons impact components of the tumor microenvironment promoting cancer initiation and progression. We have previously published that head and neck squamous cell carcinomas are innervated. We now focus on defining the contribution(s) of intra-tumoral neurons to disease progression in this cancer. Tumor implantation in a double transgenic mouse (TRPV1cre::DTAfl/wt ) that lacks the cancer-recruited TRPV1-expressing sensory neurons allows us to study the consequences of this neuronal loss on the local immune response. Thus, wildtype and TRPV1cre::DTAfl/wt mice were orthotopically implanted with tumor and tumoral immune cell populations identified by flow cytometry. Cytokine and peptide concentrations were measured by ELISA. In vitro assays were preformed to molecularly define the neuronal signals and immune responses. Here, co-culture experiments of immortalized head and neck cancer cell lines and dorsal root ganglia from wildtype mice were used to model tumor innervation in vitro. The conditioned media generated was applied to bone marrow derived (BMD) immune cells, or BMD myeloid derived suppressor cells and the impact on immune cell phenotypes assayed by flow cytometry. Utilizing a 12-color flow cytometry panel, we show that tumors from TRPV1cre::DTAfl/wt mice harbor a significantly smaller population of myeloid derived suppressor cells (MDSCs) as compared to those from wildtype animals. Further flow cytometry analysis demonstrates that this population shift occurs primarily due to a decrease in the CD11b+ Ly6G+/Ly6Clo population. In vitro studies using BMD immune cells show that tumor cell-DRG co-culture conditioned media induces an expansion of the MDSC population compared to condition media from DRG or tumor cells alone. Additionally, transwell migration assays show that co-culture condition media also increases cellular migration compared to condition media from DRG or tumor cells alone. Moreover, ELISA analysis indicates that co-culture of tumor cells and DRG increases neuronal release of the neuropeptide, Substance P (SP), which in turn potentiates IL-6 release from tumor cells. Immuno-depletion of IL-6 attenuates the in vitro generation of MDSCs. In summary, we identified several mechanisms by which TRPV1-expressing intra-tumoral neurons promote MDSC infiltration at the tumor bed and promote disease progression. These mechanisms define targets for therapeutic intervention including SP and IL-6 signaling. Future studies will test the clinical utility of these targets. Together, our data suggests that intra-tumoral neurons contribute to cancer progression through generation of a tumor supportive microenvironment.

Citation Format: Anthony C Restaino, Austin Walz, Jeffrey Barr, Paola Vermeer. TRPV1+ sensory neurons provide a tumor supportive environment through recruitment of MDSCs [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr A14.

Abstract P019: Intra-tumoral nerves regulate the local immune response at the tumor bed

Patients with highly innervated tumors have a worse prognosis than those with less innervated disease. However, the process by which intra-tumoral nerves contribute to poor outcomes remains unclear. Previously, we identified that head and neck squamous cell carcinomas (HNSCCs) are infiltrated by sensory (TRPV1+) nerves. To map the source of these tumor infiltrating nerves, we intra-tumorally injected the fluorescently tagged nerve tracer lectin, wheat germ agglutinin (WGA), in our hind limb placed HNSCC tumors. Similar to other nerve tracers, WGA is taken up at nerve terminals and retrogradely transported to the neural somas. WGA labeled the somas of dorsal root ganglia (DRG), identifying them as the source of intra-tumoral nerves. Traced nerves were further characterized by immunostaining and identified as TRPV1+ (sensory), consistent with our initial findings. To test the contributions of tumor innervation to tumor growth and survival, wildtype and TRPV1-DTA (genetically deleted of TRPV1+ neurons) mice were implanted with a mouse model of human papillomavirus-induced (HPV+) HNSCC, mEERL cells. The absence of TRPV1 nerves results in slower tumor growth and improves survival. To mechanistically define how depletion of intra-tumoral nerves reduce tumor growth, we first collected tumors 25 days after injection in the hind limb and stained with a 12-color antibody panel. Stained tumors were then analyzed with flow cytometry to identify differences in the infiltrative immune cell populations between tumors grown in C57Bl/6 control mice and our TRPV1-DTA mouse model. Flow cytometry analysis indicated a decrease in the infiltrative myeloid derived suppressor cell (MDSC) population following ablation of TRPV1+ nerves. To understand how loss of TRPV1+ nerves mediate changes in the infiltrative immune cell population we conducted cytokine array analysis of condition media from cancer cells alone and in co-culture with DRG. Results indicate a shift in secreted cytokines following co-culture with DRG. These data indicate that intra-tumoral sensory nerves are recruited from loco-regional DRG to tumors injected in the hind limb. Our data also suggest that ablation of TRPV1+ nerves alter the intra-tumoral MDSC population and, in this way, potentially contributes to tumor growth. Finally, co-culture of mEERL cells with DRG in vitro results in changes in secreted cytokines, potentially explaining the change in the infiltrative immune cell populations. Together, these data indicate a potential role for sensory nerves to regulate the local immune response in developing tumors.

Citation Format: Anthony C. Restaino, Christopher T. Lucido, Jeffrey Barr, Paola D. Vermeer. Intra-tumoral nerves regulate the local immune response at the tumor bed [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P019.

P057 Virus aerosol propagation by CPAP is proportional to mask leak and can be prevented by use of a hood and air filtration system

Introduction

Nosocomial transmission of SARS-CoV-2 has caused significant morbidity/mortality in the COVID-19 pandemic. Because patients auto-emit aerosols containing viable virus, these aerosols can be further propagated when patients undergo certain treatments including continuous positive airway pressure (PAP) therapy. This study aimed to assess the degree of viable virus propagated from mask leak in a PAP circuit.

Methods

Bacteriophage PhiX174 (108copies/mL) was nebulised into a custom PAP circuit. Mask leak was systematically varied to 0, 7, 21, 28 and 42 L/min at the mask interface. Plates containing Escherichia coli assessed the degree of viable virus settling on surfaces around the room. In order to contain virus spread a ventilated headboard and high efficiency particulate air (HEPA) filter was tested.

Results

Increasing mask leak was associated with virus contamination in a dose response manner (χ2= 58.24, df=4, p<0.001). Clinically relevant levels of leak (≥21 L/min) were associated with virus counts equivalent to using PAP with a standard vented mask. Viable viruses were recorded on all plates (up to 3.86m from source). A plastic hood with HEPA filtration significantly reduced viable viruses on all plates. HEPA exchange rates of 170 and 470m3/hr eradicated all evidence of virus contamination.

Discussion

Mask leak from PAP circuits may be a major source of environmental contamination and nosocomial spread of infectious respiratory diseases. Subclinical levels of leak should be treated as an infectious risk. Cheap and low-cost patient hoods with HEPA filtration are an effective countermeasure.

Vertebroplasty and Kyphoplasty for Osteoporotic Vertebral Fractures: What Are the Latest Data?

Osteoporotic vertebral compression fractures frequently result in significant morbidity and health care resource use. For patients with severe and disabling pain, vertebral augmentation (vertebroplasty and kyphoplasty) is often considered. Although vertebroplasty was introduced >30 years ago, there are conflicting opinions regarding the role of these procedures in the treatment of osteoporotic vertebral compression fractures. This review article updates clinicians on the published prospective randomized controlled data, including the most recent positive trials that followed initial negative trials in 2009. Analysis of multiple national claim datasets has also provided further insight into the utility of these procedures. Finally, we considered the recent recommendations of national organizations and medical societies that advise on the use of vertebral augmentation procedures for osteoporotic vertebral compression fractures.