William Maixner - US grants

Recent studies have provided evidence that behavioral and neuronal responses to noxious stimuli are attenuated by the electrical, physiological or pharmacological stimulation of vagal afferent nerves. However, a number of important issues remain to be resolved. For example, the anatomical origin of vagal afferents that impair nociceptive reflexes has not been identified. In addition, the ability of vagal afferent nerve stimulation to specifically impair responses to noxious stimuli without impairing: 1) responses to innocuous stimuli and 2) meteoric capabilities has not been evaluated. A series of reflex studies are proposed that examine the ability of vagal afferents, which arise from different peripheral sites, to selectively modulate the digastric muscle reflex elicited by intense tooth-pulp stimulation. The effects of vagal afferent nerve stimulation on the digastric reflex produced by a putative innocuous stimulus or by direct central stimulation of the reflex will also be examined. And finally, the ability to disassociate the effects of vagal afferent nerve stimulation on the digastric reflex from reflex cardiovascular responses will be examined. A second series of single unit electrophysiological studies will examine the ability of vagal afferent nerve stimulation to alter neuronal responses of functionally classified trigeminal nucleus oralis and caudalis neurons to controlled noxious and innocuous stimuli. Cells will be classified with respect to their responses to noxious and innocuous stimuli and classified as low threshold, wide-dynamic-range or nociceptive specific neurons. Cells will also be classified as trigeminothalamic projection neurons or as non-projection neurons using standard electrophysiological procedures. The ability of vagal afferent nerve stimulation to differentially alter the responses of neurons that project to different regions of the thalamus (e.g. central medial posterior vs. medial) will be examined. These studies will more precisely define the relationship between vagal afferent nerve activity and nociception. The outcomes of these and other related studies will advance our understanding of endogenous pain modulatory networks and may lead to the development of novel strategies for controlling pain.

Recent studies have provided evidence that behavioral and neuronal responses to noxious stimuli are attenuated by the electrical, physiological or pharmacological stimulation of vagal afferent nerves. However, a number of important issues remain to be resolved. For example, the anatomical origin of vagal afferents that impair nociceptive reflexes has not been identified. In addition, the ability of vagal afferent nerve stimulation to specifically impair responses to noxious stimuli without impairing: 1) responses to innocuous stimuli and 2) meteoric capabilities has not been evaluated. A series of reflex studies are proposed that examine the ability of vagal afferents, which arise from different peripheral sites, to selectively modulate the digastric muscle reflex elicited by intense tooth-pulp stimulation. The effects of vagal afferent nerve stimulation on the digastric reflex produced by a putative innocuous stimulus or by direct central stimulation of the reflex will also be examined. And finally, the ability to disassociate the effects of vagal afferent nerve stimulation on the digastric reflex from reflex cardiovascular responses will be examined. A second series of single unit electrophysiological studies will examine the ability of vagal afferent nerve stimulation to alter neuronal responses of functionally classified trigeminal nucleus oralis and caudalis neurons to controlled noxious and innocuous stimuli. Cells will be classified with respect to their responses to noxious and innocuous stimuli and classified as low threshold, wide-dynamic-range or nociceptive specific neurons. Cells will also be classified as trigeminothalamic projection neurons or as non-projection neurons using standard electrophysiological procedures. The ability of vagal afferent nerve stimulation to differentially alter the responses of neurons that project to different regions of the thalamus (e.g. central medial posterior vs. medial) will be examined. These studies will more precisely define the relationship between vagal afferent nerve activity and nociception. The outcomes of these and other related studies will advance our understanding of endogenous pain modulatory networks and may lead to the development of novel strategies for controlling pain.

This revised application requests a second 5-year period of support for a program project having the following general goals: (1) to assess the utility of approaches, instrumentation, and analysis procedures designed to enable identification and quantification of central somatosensory nervous system adaptive mechanisms in normal human subjects as well as in patient populations with orofacial sensory dysfunction; and (2) to evaluate experimentally the hypothesis that in a variety of orofacial sensory disorders (including temporomandibular disorders - TMD) the dynamic neural mechanisms which normally operate to adaptively modify the somatosensory cerebral cortical response to maintained ("tonic") somatic afferent drive function in an abnormal and maladaptive manner. The skills, prior experiences, and interests of the participating investigators are consistent with the goals proposed: collectively, the assembled research team possesses a considerable record of contributions to somatosensory neurophysiology and human psychophysics, and includes appropriate expertise in the evaluation, management, and treatment of clinical pain populations. The program involves five independent, but inter-related projects, all interacting closely with a core designed (1) to provide the number of thoroughly screened, adequately protected, and fully clinically- characterized human subjects required to satisfy project and program goals, (2) to make readily available to each project high quality and appropriate statistical and computational support, (3) to stimulate sharing and integration of the information obtained by the different projects and interpretation of that information in terms of the neural mechanisms underlying chronic orofacial sensory dysfunction, and finally, (4) to provide essential administrative support, coordination, and scientific leadership.

This FIRCA proposal describes a systematic and detailed series of in vitro pharmacological studies designed to evaluate the complex bidirectional (facilitatory and inhibitory) modulation of the stimulation-evoked release of substance P (SP) from sensory structures. We have previously demonstrated that opioids, such as morphine, produce a concentration-dependent activation of mu-1, mu, delta and kappa-opioid receptors. In the proposed studies, we will look at the release of SP evoked by high K+ concentrations, electrical stimulation and capsaicin from rat trigeminal nucleus slices. This model will enable us to determine which releasable source(s) of SP in the trigeminal nucleus is(are) modulated by opioid-receptor agonists. Then, we will elucidate whether morphine's bidirectional modulation of SP release is a direct effect mediated by opioid receptors located on SP-containing terminals or if it is an indirect effect mediated by opioid-receptors located on neighboring neurons. Finally, we will study the opioid modulation of SP release evoked by electrical stimulation that more closely approximates physiological conditions. The information gained from the proposed collaboration should contribute to our current knowledge on mechanisms underlying nociception, analgesia and hyperalgesia at the spinal level as well as to design and implement novel, well controlled clinical studies that will assess the functional significance of the experimental outcomes provided by the collaborating institution.

Dental pain is a complex sensation requiring the processing and integration of neural information at several levels of the central nervous system. Unlike other cutaneous and visceral structures, the natural stimulation of the tooth pulp or surrounding dentin produces sensations which are perceived predominately as painful. This unique sensory aspect of teeth suggests that studies designed to assess the processing of sensory information from dentin and the tooth pulp will provide useful insights into the neural mechanisms that produce pain. Neuroanatomical and electrophysiological procedures will be used to identify the somatotopic and functional representation of the dentition within the trigeminal nuclear complex. Nociresponsive trigeminal regions activated by procedures which selectively activate either A-delta or C- fibers innervating the maxillary canine will also be identified. A separate series of studies will examine the ability of morphine to produce dose-dependent, opioid-receptor mediated changes in measures of synaptic activity in response to procedures which selectively activate either A-delta or C-fiber nociceptors innervating the maxillary canine. The outcomes of these studies are consistent with the long term goals of this research program since they will advance our understanding of the neural mechanisms underlying the coding and modulation of neuronal responses to noxious orofacial stimulation.

This application seeks funds to establish a formal postdoctoral clinical and basic research training program for post-DDS and post-PhD fellows. There is a large portion of the United States population affected by orofacial sensory disorders that produce alterations in pain perception, tactile function, taste, olfaction and speech. The primary focus of this training program is to provide intensive and focused research training in areas thematically related to orofacial sensory processing and clinical orofacial sensory disorders. A multi-disciplinary team of clinical and basic neurobiologists who have an interest in sensory processing and sensory disorders will serve as training faculty. The allocation of training slots will be prioritized to find the following categories of postdoctoral trainees: 1) post-DDS trainees; 2) Post- restraining/sabbatical experience; and 4) Post-PhD fellows who want to develop an independent research career that focuses on orofacial neurobiology-with an emphasis on elucidating underlying neural mechanisms that contribute to a variety of clinically-related orofacial sensory disorders. At least one fellowship will be allocated to a mid- career scientist and at least two fellowships will be devoted to trainees who have interest in training with a faculty mentor conducting basic clinical research. Individualized research and didactic training experiences will be developed for each trainee. Each individualized training program will consist of a rigorous peer reviewed and mentored laboratory experience, attendance and participation in advanced seminars in areas related to orofacial sensory processing and sensory disorders. One of the primary goals of this training program is to train individuals who can develop independent clinical and/or basic research programs that seek to identify underlying neuromechanisms and ways of treating orofacial sensory disorders.

This application a third 5-year period for a program project having the following general goals: (1) to assess the utility of approaches, instrumentation, and neurophysiological analysis procedures designed to enable the identification and quantification of central somatosensory nervous processes in normal subjects and patient populations experiencing a variety of chronic orofacial sensory disorders; and (2) to evaluate experimentally the hypothesis that in a variety of orofacial sensory disorders, which are associated with certain types of temporomandibular disorders or which result from damage to the trigeminal nerves, occur as a consequence of abnormalities in the dynamic integration of sensory information by peripheral and central nervous system substrates that respond to noxious and non-noxious somatosensory stimuli. The skills, prior experiences, and interests of the investigative team is consistent with the goals proposed, and collectively, the assembled research team possesses a considerable record of contributions to somatosensory physiology and human psychophysics, and includes appropriate expertise in the evaluation management, and treatment of clinical pain populations. The Program involves four interactive scientific projects, ill interactive with a Core designed to: (1) provide the number of carefully screened and characterized human subjects and patients required to satisfy each subproject's specific aims; (2) make available to each subproject high quality and targeted statistical consultation; (3) stimulate sharing and integration the information obtained by the different projects and the interpretation of that information in terms of the neural mechanisms underlying chronic orofacial sensory disorders, and finally; (4) provide essential administrative support, coordination, and scientific leadership.

Administrative Core. The Administrative Core is composed of Dr, William Maixner (Program Director) and Dr. Richard Gracely (Associate Program Director). This Core will oversee the administrative activities of the Program and provide assistance to the individual subprojects in administrative matters. Most importantly, it will provide an infrastructure for the integration of findings from the individual subprojects for attainment of the Program's goals. Accordingly, the specific aims and funcfion of this core are to: 1. Coordinate the administrafive activifies of the Program and the individual subprojects (e.g., assist in the management of budgets and personnel). 2. Promote a scholariy environment by coordinafing the Program's seminar series and visits by external scientists. 3. Meet weekly and review administrative issues and concerns of the Program. 4. Meet monthly with the principal investigators and core directors to discuss progress and problems encountered by the individualsubprojects. 5. Assemble every six months Program investigators, postdoctoral fellows, graduate research assistants, consultants as available, and staff to (i) identify concordant and discordant research findings among subprojects, (ii) evaluate the Program's working hypotheses, (iii) determine if changes or refinements in protocols are needed, and (iv) promote creative thinking and reinforce interactions among the Program team members. 6. Coordinate annual meetings of the Program's External Scientific Advisory Committees with the entire invesfigative team.

DESCRIPTION (provided by applicant): The central theme of this Program Project is that the dimensions of the pain experience (e.g., pain intensity, localization, and persistence) can far exceed those expected on the basis of peripheral tissue injury or pathology whenever CNS regulatory systems are dysfunctional. Up to now, a lack of methods for the direct evaluation and characterization of the status of these systems has deterred progress in understanding CNS pain regulatory mechanisms. To address this gap, state-of-the-art human psychophysical and neuroimaging methods (combined quantitative EEG and fMRI) will be used to evaluate, at the level of the cerebral cortex, the status of CNS pain and touch regulatory mechanisms in patients diagnosed with fibromyalgia syndrome (FM) and with myogenous temporomandibular dysfunction (TMD), and in normal healthy subjects. Psychophysical findings have suggested abnormalities in three such processes that will be targeted by the proposed psychophysical and neuroimaging experiments: diffuse noxious inhibitory control (DNIC, inhibition of pain by pain), the touch gate (inhibition of mechanoreception by pain), and the pain gate (inhibition of pain by mechanoreception). In addition, longitudinal epidemiological approaches will be used to determine whether abnormalities in CNS regulatory systems predict the subsequent development of TMD in otherwise healthy young adult females. The primary hypothesis that guides this work is that dysfunction(s) within CNS regulatory systems increases pain sensitivity and represents an important risk factor that contributes to the development of central sensitization which leads to persistent musculoskeletal pain conditions like myogenous TMD. The long-term goals of this Program Project are to: 1) To obtain experimental evidence enabling mechanistic interpretation and quantification of the physiological/biological processes that mediate the intense, abnormally widespread, and persistent pain exhibited by patients with disorders of central sensitization. 2) To develop and validate novel psychophysiological and neurophysiological approaches that permit quantitative assessment of the peripheral and CNS pathophysiology associated with disorders of central sensitization and pain regulation. 3) To establish an environment that enables effective and productive interactions between basic scientists and clinicians interested in central pain and its regulation. 4) To generate a research environment that facilitates translation of basic science findings into therapeutic interventions for the treatment of persistent musculoskeletal pain.

This project will extend the collection and analysis of data from a prospective study that is currently in its 5th year. This first of its kind prospective study seeks to identify the primary biopsychosocial factors that contribute to the development and maintenance of myogenous TMD. The primary hypothesis that guides this work is that dysfunction(s) within CNS regulatory systems increases pain sensitivity and represents an important risk factor that contributes to the development of central sensitization which leads to persistent musculoskeletal pain conditions like myogenous TMD. In addition to extending this ongoing project, we will examine the ability of beta-adrenergic blockade to restore impaired pain regulatory systems and to diminish the signs and symptoms of FM and TMD. A randomized double blind mechanistic drug trial will examine whether beta-adrenergic blockade is able to impact pain and associated co-morbid conditions in patients with FM and TMD. The effects of short-term treatment with the nonselective beta-adrenergic antagonist propranolol or a placebo on pain regulatory systems and measures of pain, sleep and function, will be assessed in the home environment using diary procedures. The ability of beta-blockade to augment DNIC and to diminish central sensitization and windup in patients with FM and TMD will be examined.

DESCRIPTION (provided by applicant): Risk factors for onset and persistence of TMD: Myogenous temporomandibular disorder (TMD), with or without arthralgia, ranks second only to headache as the clinical condition most likely to cause craniofacial pain and dysfunction in the U.S. population. During the last decade, a small number of epidemiological studies have attempted to quantify the incidence of TMD in populations of European heritage;however, no investigative team to date has undertaken a large-scale, hypothesis-driven, prospective study designed to identify biopsychosocial and genetic risk factors for the onset and persistence of this vexing pain disorder. We propose to conduct a comprehensive, prospective cohort study of the incidence of TMD in collaboration with an internationally recognized group of epidemiologists, pain researchers, and geneticists. Participants will be enrolled and followed prospectively at four research institutions and by our Data Coordinating Center (Battelle Memorial Institute). Our three goals are to: a) undertake a five-year, prospective cohort study of 3200 initially TMD-free individuals recruited from major ethnic and racial strata at four study sites, quantifying incidence rates of first-onset-TMD;b) undertake a case-control study by recruiting 200 people with chronically symptomatic TMD identified during cohort recruitment whose history of TMD precludes them from the prospective study;c) to identify in both groups the individual and joint effects of predictors of TMD risk using a conceptual, causal model for TMD that we have developed based our own studies and other published research. Our preliminary epidemiological findings have led to the central hypothesis that pain amplification and psychological factors, both of which are influenced by genetic variants, represent causal risk factors that influence TMD onset and persistence. The outcomes of our proposed study will identify the primary socio-demographic, clinical, biological, psychological, and genetic risk factors for TMD onset and persistence. In so doing, we will obtain important and novel information regarding the etiopathogenesis of TMD, which will assist with the development of evidenced based pharmacological and behavioral interventions for TMD.

CRISP; Computer Retrieval of Information on Scientific Projects Database; Condition; Disease; Disorder; Funding; Grant; Institution; Investigators; Learning; NIH; National Institutes of Health; National Institutes of Health (U.S.); Pain; Painful; Purpose; Regulation; Research; Research Personnel; Research Resources; Researchers; Resources; Screening procedure; Source; United States National Institutes of Health; Visit; Woman; chronic pain; chronic painful condition; disease/disorder; screening; screenings

This project will extend the collection and analysis of data from a prospective study that is currently in its 5th year. This first of its kind prospective study seeks to identify the primary biopsychosocial factors that contribute to the development and maintenance of myogenous TMD. The primary hypothesis that guides this work is that dysfunction(s) within CNS regulatory systems increases pain sensitivity and represents an important risk factor that contributes to the development of central sensitization which leads to persistent musculoskeletal pain conditions like myogenous TMD. In addition to extending this ongoing project, we will examine the ability of beta-adrenergic blockade to restore impaired pain regulatory systems and to diminish the signs and symptoms of FM and TMD. A randomized double blind mechanistic drug trial will examine whether beta-adrenergic blockade is able to impact pain and associated co-morbid conditions in patients with FM and TMD. The effects of short-term treatment with the nonselective beta-adrenergic antagonist propranolol or a placebo on pain regulatory systems and measures of pain, sleep and function, will be assessed in the home environment using diary procedures. The ability of beta-blockade to augment DNIC and to diminish central sensitization and windup in patients with FM and TMD will be examined.

DESCRIPTION (provided by applicant): Complex persistent pain conditions (CPPCs) such as headache conditions, fibromyalgia, temporomandibular disorders, irritable bowel syndrome, and vulvar vestibulitis are high prevalent and shared or comorbid chronic pain conditions. There are two features of CPPCs that are fundamental to the aims and goals of this proposal: 1) the etiology of CPPCs is multifactorial and 2) the clinical manifestations of CPPCs are diverse. In this Program Project, we expect to identify a mosaic of risk factors for each of five CPPCs: fibromyalgia (FM), episodic migraine (EM), vulvar vestibulitis (VVS), irritable bowel syndrome (IBS), and temporomandibular joint disorders (TMD). Furthermore, we expect to characterize clusters of patients within each CPPC that vary significantly according to manifestations of their condition in addition to its painful characteristics (e.g., fatigue, dysfunction, sleep loss). Importantly, we expect some clusters of patients to be more alike across CPPCs than within any single CPPC, consistent with our view that there is some overlap in the manifestations of CPPCs. A unifying hypothesis integrating this Program is that multiple genetic factors, when coupled with environmental exposures (e.g. injury, infections, physical and psychological stress), increase the susceptibility to highly prevalent CPPCs by enhancing pain sensitivity and/or increasing psychological distress. To address the aims and goals of the subprojects and cores described in this application, a group of accomplished pain clinicians, pain researchers, psychophysiologists, molecular and cellular geneticists, biostatisticians and epidemiologists have been brought together to form this Program. Studies proposed in this Program Project application seek to identify the psychological and physiological risk factors, clusters, and associated genetic polymorphisms, that influence pain amplification and psychological profiles in enrollees who have established CPPDs. Additionally, the proposed studies seek to characterize the biological pathways through which these genetic variations causally influence CPPCs.

DESCRIPTION (provided by applicant): While virtually everyone experiences acute pain at some time, it is chronic pain that exacts a profound burden on the public health, reducing quality of life for tens of millions Americans, and incurring substantial health care costs. Yet little is known about mechanisms that cause a transition from acute to chronic pain; subsequently, event the best of treatments have limited efficacy. One likely clue regarding etiology is that patients who have one form of chronic pain often experience chronic pain elsewhere in the body. In this project, we hypothesize that the transition from acute to chronic pain and the development of multiple chronic pain conditions, are caused by specific constellations of genetic variants and phenotypic risk factors (ie. psychological distress, pain amplification and clinical pain characteristics). This hypothesis is based on our studies of temporomandibular disorder (TMD) in the multi-site OPPERA project (Orofacial Pain, Prospective Evaluation and Risk Assessment; NIH/NIDCR U01-DE017018). In 2006-08, we enrolled 3,263 healthy adults, 233 of whom developed acute TMD during the 3-year follow-up period. Risk factors for acute TMD differed conspicuously from genetic and phenotypic risk factors for chronic TMD. Furthermore, 86% of chronic TMD cases had one or more of four chronic, idiopathic pain conditions: headache (HA), low back pain (LBP), irritable bowel syndrome (IBS) or widespread bodily pain (WBP). In this competitive renewal application, we propose three new aims designed to reveal novel information regarding the etiology and pathophysiology of chronic pain. Aim 1: To identify phenotypes and genotypes that predict risk of transition from acute TMD to chronic TMD, we will enroll a new cohort of 1,000 adults who have acute TMD, following them for six months to identify an expected 400 who progress to chronic TMD. Aim 2 will identify risk factors for one or more of five: idiopathic pain conditions (IPCs): TMD, HA, LBP, IBS and/or WBP. Follow-up assessments will be conducted among people in the OPPERA-I prospective cohort study, identifying an expected 640 people who have ¿1 IPC. Existing phenotypes and genotypes measured at baseline will be used to predict risk of 1 IPC vs. ¿2 IPCs relative to controls. Aim 3 will identify genetic variants associated with chronic TMD. A discovery-phase genome wide association study (GWAS) will use existing DNA from 1,000 OPPERA-I chronic TMD cases and 1,000 OPPERA-I controls. Replication will use a new cohort of n=1,000 chronic TMD cases and n=1,000 controls. Those findings will be contrasted with GWAS analysis of the cohort for Aim 1 to identify genes that contribute differentially to acute and chronic TMD. Based on these findings and validated associations from other studies, twelve genes will be selected for exon sequencing of rare genetic variants. Knowledge generated from these proposed studies will have a significant impact on scientific understanding of risk factors for multiple, overlapping pai conditions. Moreover, the findings will be of direct benefit for clinicians and for their patients, elucidating mechanisms underlying chronic and idiopathic pain in people with TMD.

DESCRIPTION (provided by applicant): The current proposal is a competitive revision to the Program Project (2P01NS045685-06A1-PI Dr Maixner) in which we propose to explore the role of mitochondrial inheritance as a shared pathway for co-morbid Complex Persistent Pain (CPP) conditions. Our group has recent data suggesting that certain mitochondrial DNA (mtDNA) polymorphisms are associated with several CPP, including migraine and IBS, suggesting that impaired energy metabolism may be a shared pathway. In this revision we will explore the relationship between polymorphic changes in the entire mtDNA to identify candidate polymorphisms associated with CPP. This is a novel pathway to be explored in CPP and fits seamlessly into the goals of the Program Project. Exploring mtDNA, in addition to nuclear DNA, psychological and physiological factors as already proposed in this program project grant, would enhance our understanding of the shared risk factors for complex persistent pain disorders. To this end, existing blood samples obtained in the project grant will be used for genetic analyses, supplemented with banked samples. In a subgroup (N=400) of patients and controls, we will cyclosequence the entire mtDNA. Any polymorphism demonstrating a potential trend association with CPP, will be studied by PCR-RFLP in the whole sample (N=1850). In addition, detailed pedigrees will be obtained to determine the presence and degree of a maternal inheritance pattern of functional symptoms/disorders and association with identified polymorphisms. Data collected on mtDNA will be integrated with nuclear genetic data for analysis and modeling within the original aims of the PPG. Identification of disease-associated mtDNA sequence variants could provide mechanistic insight and clinical advances, and establish a new pathogenic model for understanding mtDNA-mediated polygenic susceptibility in CPP.

DESCRIPTION (provided by applicant): Complex persistent pain conditions (CPPCs) such as headache conditions, fibromyalgia, temporomandibular disorders, irritable bowel syndrome, and vulvar vestibulitis are high prevalent and shared or comorbid chronic pain conditions. There are two features of CPPCs that are fundamental to the aims and goals of this proposal: 1) the etiology of CPPCs is multifactorial and 2) the clinical manifestations of CPPCs are diverse. In this Program Project, we expect to identify a mosaic of risk factors for each of five CPPCs: fibromyalgia (FM), episodic migraine (EM), vulvar vestibulitis (VVS), irritable bowel syndrome (IBS), and temporomandibular joint disorders (TMD). Furthermore, we expect to characterize clusters of patients within each CPPC that vary significantly according to manifestations of their condition in addition to its painful characteristics (e.g., fatigue, dysfunction, sleep loss). Importantly, we expect some clusters of patients to be more alike across CPPCs than within any single CPPC, consistent with our view that there is some overlap in the manifestations of CPPCs. A unifying hypothesis integrating this Program is that multiple genetic factors, when coupled with environmental exposures (e.g. injury, infections, physical and psychological stress), increase the susceptibility to highly prevalent CPPCs by enhancing pain sensitivity and/or increasing psychological distress. To address the aims and goals of the subprojects and cores described in this application, a group of accomplished pain clinicians, pain researchers, psychophysiologists, molecular and cellular geneticists, biostatisticians and epidemiologists have been brought together to form this Program. Studies proposed in this Program Project application seek to identify the psychological and physiological risk factors, clusters, and associated genetic polymorphisms, that influence pain amplification and psychological profiles in enrollees who have established CPPDs. Additionally, the proposed studies seek to characterize the biological pathways through which these genetic variations causally influence CPPCs.

DESCRIPTION (provided by applicant): Temporomandibular Joint Disorders (TMJD) and Orofacial Pain (OFP) are complex and multi-factorial pain disorders involving genetic, social, cultural, biobehavioral, and environmental factors. To effectively manage these conditions, multi-and inter-disciplinary teams of TMJD and OFP basic and clinical researchers are needed to adequately address the multi-factorial nature of these conditions. This document represents an institutional response from the University of North Carolina at Chapel Hill (UNC-CH) School of Dentistry's (SOD) Center for Neurosensory Disorders (CNSD) to NIDCR PAR-11-289: Institutional Career Development Award for Enhancing Research Capacity in Temporomandibular Joint Disorders and Orofacial Pain (K12). The purpose of this proposed Biomedical Researcher Development Scholarship (BRDS) program is to develop a cohort of successful and independent basic, clinical and translational research scholars who can lead multi- disciplinary research teams to apply novel approaches to TMJD and OFP research that will improve the understanding of these disorders and lead to more effective methods of diagnosis and treatment. Our program embraces the full spectrum of basic, translational and clinical research including mechanisms of acute and chronic pain, therapeutic intervention, clinical trials, epidemiology, social, and behavioral clinical research related to TMJD, OFP and related comorbid pain disorders. A strong focus on the biopsychosocial and molecular genetic mechanisms that contribute to TMJD and OFP will be emphasized. BRD scholars will have the opportunity to carry out supervised biomedical, epidemiological, health services/health policy, or clinical research with the primary objective of developing or enhancing multi-disciplinary collaborative research skills and knowledge in preparation for an independent research career relevant to the mission of the NIDCR. This career development award proposes to enhance the research capacity of scholars in the field of TMJD and OFP research by achieving the following objectives: 1) To attract and engage junior or new basic and clinical investigators trained in sciences relevant to TMJD and OFP who are from diverse biomedical backgrounds into the field of TMJD and OFP research; 2) To mentor and nurture these research scholars and equip them with the necessary knowledge and skills to pursue independent research careers in TMJD and OFP; 3) To integrate the research scholars into a multi- and inter-disciplinary research environment that will foster the development of collaborative scientific advancement as well as enhance individual skills and expertise; 4) To assist BRD scholars with the development of K08, K23 or R series awards, or with other mechanisms of research training support and career development; 5) To groom these research scholars to become future leaders of multi- and inter-disciplinary collaborative research teams; and 6) To continue to support and mentor scholars following completion of their BRDS. Our goal is to create a new cadre of multi-disciplinary and highly interactive scientists who can serve as the next generation of TMJD and OFP research leaders.

Mounting evidences suggests that cancers such as melanoma produce programmed death protein-1 ligand 1 (PD-L1) to suppress T cell activation and immunity via interaction with PD-1 (receptor of PD-L1). Emerging immune therapies such as anti-PD1 and anti-PD-L1 treatments have shown great success in treating cancers, such as melanoma and head and neck cancers. However, the unique role of PD-L1/PD-1 in pain regulation is unknown. Our work in progress has demonstrated the presence of anatomical and functional PD-1 in primary sensory neurons and identified PD-L1 as a novel pain inhibitor, produced not only by cancer cells but also by normal neural tissues. We hypothesize that PD-L1 masks cancer pain and inhibits baseline pain and neuropathic pain via silencing PD-1 expressing nociceptive neurons. We also hypothesize that PD-L1 can inhibit somatic and trigeminal neuropathic pain via suppressing microglial and T-cell activation in the spinal cord and brain stem. Of interest recent studies have shown that microglia and T cells in the spinal cord contribute to neuropathic pain in a sex-dependent manner. Consistently, our pilot study shows that intrathecal inhibition of caspase-6 and p38 signaling inhibits nerve injury-induced mechanical allodynia in male but not female mice. We further hypothesize that PD-L1 inhibits microglial and T-cell activation in a sex-dependent manner. The overall goal of this application is to investigate how the PD-L1/PD-1 pathway can mask cancer pain and also suppress neuropathic pain via regulating the function of neurons, microglia, and T-cells. We will use mouse melanoma and neuropathic pain models of both sexes to test our hypotheses by accomplishing the following 3 specific aims: Aim 1. Test the hypothesis that the PD-L1/PD-1 pathway can mask skin cancer pain, suppress somatic and trigeminal neuropathic pain, and inhibit baseline pain; Aim 2. Test the hypothesis that activation of the PD- L1/PD-1 pathway can suppress neuronal excitability in mouse and human DRG/TG neurons and inhibit synaptic plasticity in mouse spinal cord neurons; Aim 3. Test the hypothesis that the PD-L1/PD-1 pathway can inhibit pain via suppressing microglial and T-cell activation in a sex-dependent manner. This project will identify PD-L1 as a novel endogenous pain inhibitor and provide new insights into neuron-glia, neuron-immune, and neuron- cancer interactions. Manipulation of PD-L1/PD-1 signaling may lead to the development of novel analgesics.

ABSTRACT Chronic pain is a major health problem that afflicts one third of Americans. New research that can aid the development of new pain-relieving strategies is urgently needed. Our proposal focuses on identifying and validating a new central analgesic circuit. This project is based on a highly innovative hypothesis that the strong analgesic effect of general anesthesia (GA) is in part carried out by GA-mediated activation of the endogenous analgesic circuits. In preliminary studies, we discovered that a subset of GABAergic neurons located in the central amygdala (CeA) become strongly activated and express high level of the immediate early gene Fos under GA (hereafter referred to as CeAGA neurons). Excitingly, using our recently developed activity-dependent tagging system called CANE (Capturing Activated Neuronal Ensemble), we were able to capture CeAGA neurons and discovered that activating these neurons exerted profound pain-suppressing effects in an acute pain model and a chronic orofacial neuropathic pain model. Based on these exciting preliminary results, we propose to identify and validate CeAGA neurons? analgesic functions in multiple mouse pain models conducted in different labs (Wang and Ji, co-PI). In aim 1, we will systematically activate and silencing CeAGA analgesic neurons and test the consequences of such bi- directional manipulations on regulating the sensory-discriminative and emotional-affective aspects of pain processing in naïve mice and in several mouse models of acute and chronic pain models with cross validation between the two labs. In aim 2, using the state-of-the-art in vivo imaging technology, we will test the hypothesis that the spontaneous activities of CeAGA analgesic neurons are severely reduced in various chronic pain models compared to naïve conditions, leading to pain hypersensitivity in these models (due to the suppression of this endogenous analgesic circuit); and complimentary, we will use slice electrophysiology to examine changes in intrinsic and evoked properties of CeAGA analgesic neurons in normal and chronic pain conditions which may explain the altered in vivo activities. In aim 3, based on preliminary results showing extensive axonal projections of CeAGA to many brain areas, we will identify the critical subsets of CeAGA projection pathway(s) for their analgesic effect in different chronic pain models. We expect to identify shared common pathways that need to suppressed by specific subtypes of CeAGA analgesic neurons in all models, and such information will be critical for developing precise CeAGA-based therapies. In summary, this research is expected to identify and validate a novel central analgesic circuit whose power can be harnessed to treat chronic pain.

The primary goal of this proposal is to establish Baroreflex Sensitivity (BRS) as a biomarker for acute postoperative pain (POP) and the likelihood of persistent postoperative pain (PPP) at the 3 month postoperative timepoint in patients undergoing video-assisted thoracic surgery (VATS). Our central hypothesis is that preoperative BRS is inversely associated with the magnitude and duration of POP during postoperative days 0-2 and the likelihood of PPP at 3 months throughout the postoperative observation by influencing nociceptive processing and surgically-induced inflammation. If this central hypothesis is confirmed then future interventional studies designed to enhance BRS will be developed with the goal of optimizing perioperative outcomes.

The goal of this program project is to establish a NCCIH Center of Excellence is to investigate neuroinflammatory mechanisms underlying multiple complementary and integrative health (CIH) approaches, including electroacupuncture and natural product docosahexaenoic acids. The overarching hypothesis for the entire P01 is that different CIH approaches may modify distinct inflammatory and neuroinflammatory profiles to achieve their therapeutic potentials in pain management. This hypothesis will be tested in 4 projects using four animal models relevant to different types of clinical pain conditions, in combination with sex and stress. In response to rising opioid crisis in the US, this PPG will conduct cutting-edge basic science research and pave the road for future clinical trial at the center for rapid translation of the identified complementary approaches that can effectively modulate neuroinflammation.

The measurement of behavioral signs of evoked and spontaneous pain in rodents is essential to the success of all the 4 subprojects in this program. The Behavioral Core includes 8 newly designed test rooms in a new research Building (MSRBIII). All the behavioral tests in Aim 1 and Aim 2 of all 4 projects will be conducted blindly by three well-trained technicians. All the behavioral data will be saved electronically, analyzed by two statisticians, and shared with Project PIs. We will measure evoked pain such as mechanical allodynia and cold allodynia in both sexes in 4 clinically relevant mouse models of pain. We will also test ongoing pain using conditioned place preference and avoidance (CPP and CPA). We will also measure pain-associated co- morbidity, such as anxiety and depression. We will test the hypothesis that swim stress can prolong the duration of pain. Pain-related behaviors will be tested before and after complementary treatments such as electroacpuncture and DHA. The central hypothesis of this Program Project is that multiple complementary approaches, including electroacupuncture and natural product DHA, may modify distinct inflammation and neuroinflammation processes. We will test our hypotheses in four clinically relevant animal models via the following specific aims: Specific Aim 1: Define the time course of neuropathic pain, postoperative pain, functional pain, and trigeminal pain in 4 clinically relevant mouse models and test the effects of stress and sex on the duration of pain in these models; Specific Aim 2: Ascertain the effects of pre-treatment and post- treatment of EA, aEA, DHA, and RvD1 on neuropathic pain, postoperative pain, functional pain, and trigeminal pain in 4 mouse models; Specific Aim 3 (Exploratory): Develop operant behavioral assays for non-reflexed ongoing pain. We will develop and optimize operant measurement of orofacial pain using Orofacial Stimulation of Ugo Basile. We will also optimize vocalization for detecting acute and chronic pain. Testing behavior in different animal models by the same experienced personnel in the Behavioral Core and collecting the data using electronic-data-report-system will enhance the Scientific Rigor and Reproducibility of the PPG.