Faculty Bibliography

Following peripheral nerve injury, Schwann cell (SC) survival is imperative for successful nerve regeneration. The low-density lipoprotein receptor-related protein-1 (LRP1) has been identified as a pro-survival SC plasma membrane signaling receptor, however, the responsible mechanisms underlying SC homeostasis remain incompletely understood. Herein, we establish that LRP1 largely manages mitochondrial dynamics and bioenergetics in SCs by limiting mitochondria fission, maintaining healthy mitochondria membrane potentials, and reducing lactate production associated with peripheral sensitization. When SC LRP1 is suppressed, inner-mitochondria-linked pathways in peripheral nerve proteome are dramatically altered, and cristae integrity in unmyelinated C-fibers is compromised. SC LRP1 protected sensory neurons from mitochondrial dysfunction and modulated mitochondria-related biological pathways in the DRG transcriptome. Conditional deletion of LRP1 in SCs induces pain-related behaviors in mice without nerve injury. Results point to a significant role for LRP1 in SC mitochondrial homeostasis and advance our understanding of the sensory neuron response to alterations in SC bioenergetics.

Perineural invasion (PNI) frequently occurs in head and neck squamous cell carcinoma (HNSCC), which correlates with poor survival and induces intractable pain and numbness. There is no effective treatment for PNI or associated pain. To gain a better understanding of PNI at the molecular and cellular level, we produced an orthotopic, syngeneic mouse model of PNI by inoculating mouse oral cancer cells into the infraorbital nerve (ION), a nerve that is susceptible to cancer invasion in patients with HNSCC. Mice with PNI in the ION exhibited both evoked and spontaneous nociception and impaired oral function, mimicking human conditions. PNI resulted in a drastic reduction in the proportion and altered mechanical thresholds in mechanically sensitive trigeminal neurons; axon and myelin abnormalities, as well as phagocytic cells, were observed. The tumor bed is marked by CD4⁺ and CD8⁺ T cells, CD68⁺ cells, and F4/80⁺ macrophages, while CD4⁺, CD8⁺, and CD68⁺ immune cells can be found surrounding the nerve. The intraneural niche is predominantly marked by CD68 that does not overlap with F4/80 but instead overlaps with NF200 and MPZ and occasionally with DAPI, suggesting these are likely phagocytic macrophages or Schwann cells. Finally, our RNA sequencing pathway analysis in mouse and human HNSCC found perturbed pathways in neuroinflammation, mitochondrial dysfunction, and cellular metabolism. Additionally, ION-PNI exhibits nerve degenerative features with perturbed pathways that are observed in Alzheimer, Parkinson, and prion diseases. In conclusion, we report a novel, anatomically relevant in vivo model that could be used to study the cellular and molecular mechanisms of PNI-induced neuropathies. Importantly, we found that PNI resembles neurodegenerative diseases with features of altered sensory transduction and conduction, neuroinflammation, and mitochondrial dysfunction, which may underlie peripheral neuropathies, such as pain.

BACKGROUND:This exploratory cross-sectional observational study sought to characterize sleep quality and evaluate its association with sociodemographic, clinicopathological, behavioral, and psychological variables in patients with head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS/METHODS:Sleep problems from 132 HNC patients were assessed before starting oncological treatment through the questionnaires Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), and STOP-Bang. Anxiety and depression symptoms were evaluated using the Hospital Anxiety and Depression Scale. Univariate analysis and multivariate logistic regression were performed to evaluate factors associated with sleep problems in HNSCC patients. RESULTS:About 50% of the HNSCC patients reported poor overall sleep quality on the PSQI. Insomnia, excessive daytime sleepiness, and high risk of apnea were observed in 19%, 15%, and 54% of HNSCC patients, respectively. Our results showed that pain was associated with overall poor PSQI sleep quality and lower PSQI sleep efficiency, while the presence of regional metastasis was linked to overall PSQI good sleep. No other clinicopathological or behavioral (i.e., alcohol and tobacco use) variables were related to sleep outcomes. Higher occurrence of anxiety symptoms was related to poor overall PSQI sleep quality, decreased PSQI sleep efficiency, PSQI daytime dysfunction, and ISI insomnia. Moreover, higher occurrence of depression symptoms was associated with lower PSQI sleep latency and PSQI duration, and the occurrence of ESS excessive daytime sleepiness. CONCLUSION/CONCLUSIONS:Pain, anxiety, and depressive symptoms were associated with poor sleep quality and sleep problems in HNSCC patients before starting treatment. No sociodemographic or behavioral (i.e., alcohol and tobacco use) variables were related to sleep outcomes. Likewise, tumor location, T classification, and clinical staging were not linked to sleep quality and disorders in HNSCC patients.

Preclinical studies addressing the peripheral effects of cancer perineural invasion report severe neuronal availability and excitability changes. Oral cell squamous cell carcinoma perineural invasion (MOC2-PNI) shows similar effects, modulating the afferent's sensibility (tactile desensitization with concurrent nociceptive sensitization) and demyelination without inducing spontaneous activity (see Part 1.). The current study addresses the electrical status (normal or abnormal) of both active (low threshold mechano receptors (LT) and high threshold mechano receptors (HT)) and inactive (F-type and S-type) afferents. Concurrently, we have also evaluated changes in the genetic landscape that may help to understand the physiological dynamics behind MOC2-PNI-induced functional disruption of the peripheral sensory system. We have observed that the altered cell distribution and mechanical sensibility of the animal's somatosensory system cannot be explained by cellular electrical dysfunction or MOC2-PNI-induced apoptosis. Although PNI does modify the expression of several genes related to cellular hypersensitivity, these changes are insufficient to explain the MOC2-PNI-induced aberrant neuronal excitability state. Our results indicate that genetic markers provide limited information about the functional hyperexcitable state of the peripheral system. Importantly, our results also highlight the emerging role of plasma membrane Ca2+-ATPase activity (PMCA) in explaining several aspects of the observed gender-specific neuronal plasticity and the reported cellular distribution switch generated by MOC2-PNI.

Patients with cancer perineural invasion (PNI) report greater spontaneous pain and mechanical allodynia. Here, we examine the impact of the disease on the peripheral sensory system, the excitability changes induced by PNI at the dorsal root ganglia, and the potential protective role of the absence of Tumor Necrosis Factor-α Receptor 1 (TNFR1). To study these effects, we use a murine model generated by injecting mouse oral cancer squamous cell carcinoma (MOC2) into the sciatic nerve (MOC2-PNI) in both male and female mice. We found that MOC2-PNI induces a profound change in the somatosensory landscape by deactivating/blocking the peripheral inputs while modulating the afferent's sensibility (tactile desensitization with concurrent nociceptive sensitization) and demyelination without inducing spontaneous activity. All these changes caused by MOC2-PNI are unmitigated by the absence of TNFR1. We conclude that MOC2-PNI induces an aberrant neuronal excitability state and triggers extreme gender-specific neuronal plasticity. These data allow us to speculate on the role of such plasticity as a powerful defense mechanism to prevent terminal sensory dysfunction, the rise of chronic pain, and extend animals' survivability.

Cancer neuroscience is a rapidly growing multidisciplinary field that conceptualizes tumors as tissues fully integrated into the nervous system. Recognizing the complexity and challenges in this field is of fundamental importance to achieving the goal of translational impact for cancer patients. Our commentary highlights key scientific priorities, optimal training settings, and roadblocks to translating scientific findings to the clinic in this emerging field, aiming to formulate a transformative and cohesive path forward.

Patients with diabetes mellitus (DM) have an increased risk of tooth decay caused by alterations in their tooth development and their oral environment, as well as a tendency to present with pulp infection due to compromised immune response. The present study analyzed the characteristic alterations in tooth development under DM conditions using incisors from db/db type 2 diabetic mouse model (T2DM mice). In micro-CT analyses, T2DM mice showed delayed dentin and enamel formation. Through transcriptomic analyses, pre-ameloblast- and pre-odontoblast-specific genes were found to be significantly decreased in the incisors of T2DM mice, whereas major ameloblast- and mature odontoblast-specific genes were not changed. Stem cell markers were decreased in T2DM mice compared to those from the control mice, suggesting that the stemness of dental pulp cells (DPCs) is attenuated in T2DM mice. In vitro analyses demonstrated that DPCs from T2DM mice have lower colony-forming units (CFU), slower propagation, and diminished differentiation characteristics compared to the control. These data suggest that T2DM conditions could impair the differentiation property of multiple progenitor/stem cells in the tooth, resulting in delayed tooth development in T2DM mice.

Head and neck squamous cell carcinoma (HNSCC) is painful, and perineural invasion (PNI) has been associated with the worst pain. Pain due to HNSCC is diverse and may vary based on clinicopathological factors. This study aims to characterize different pain patterns linked with PNI, its influence on daily functioning, and gain insights into molecular changes and pathways associated with PNI-related pain in HNSCC patients. We conducted a cross-sectional study across 3 medical centers (n = 114), assessing pain phenotypes and their impact on daily functioning using 2 self-reported pain questionnaires, given to patients prior to their cancer surgery. Furthermore, we conducted RNA-seq analysis utilizing the The Cancer Genome Atlas dataset of HNSCC tumor from patients (n = 192) to identify genes relevant to both PNI and pain. Upon adjusting for demographic and clinicopathological variables using linear regression models, we found that PNI independently predicted function-evoked pain according to the University of Calfornia San Francisco Oral Cancer Pain Questionnaire, as well as the worst pain intensity reported in the Brief Pain Inventory. Distinct pain patterns were observed to be associated with daily activities in varying manners. Our molecular analyses revealed significant disruptions in pathways associated with the extracellular matrix structure and organization. The top differentially expressed genes linked to the extracellular matrix are implicated in cancer development, pain, and neurodegenerative diseases. Our data underscore the importance of properly categorizing pain phenotypes in future studies aiming to uncover mechanistic underpinnings of pain. Additionally, we have compiled a list of genes of interest that could serve as targets for both cancer and cancer pain management. PERSPECTIVE: PNI independently predicts function-evoked pain. Different pain phenotypes affect daily activities differently. We identified a list of candidate genes involved in the extracellular matrix structure and function that can be targeted for both cancer and cancer pain control.

Oral squamous cell carcinoma (OSCC) biomarker studies rarely employ multi-omic biomarker strategies and pertinent clinicopathologic characteristics to predict mortality. In this study we determine for the first time a combined epigenetic, gene expression, and histology signature that differentiates between patients with different tobacco use history (heavy tobacco use with ≥10 pack years vs. no tobacco use). Using The Cancer Genome Atlas (TCGA) cohort (n = 257) and an internal cohort (n = 40), we identify 3 epigenetic markers (GPR15, GNG12, GDNF) and 13 expression markers (IGHA2, SCG5, RPL3L, NTRK1, CD96, BMP6, TFPI2, EFEMP2, RYR3, DMTN, GPD2, BAALC, and FMO3), which are dysregulated in OSCC patients who were never smokers vs. those who have a ≥ 10 pack year history. While mortality risk prediction based on smoking status and clinicopathologic covariates alone is inaccurate (c-statistic = 0.57), the combined epigenetic/expression and histologic signature has a c-statistic = 0.9409 in predicting 5-year mortality in OSCC patients.

Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact.