Research Group Funded Research

Development of Anti-OLAM Aptamers as Novel Analgesics
Mechanisms of airway neurogenic inflammation by asthma-inducing allergens
MMP Inhibitor for Orofacial Pain
A New Method to Treat Burn Pain in Our Wounded Warriors
A Novel Approach to Pain Control
Role of Oxidized Linoleic Acid Metabolites in Pain – OLAM-CFA R01
Estrogen Modulation of Human Nociceptors – R01 NS058655
Prolactin Modulation of Trigeminal Nociceptors – R01 DE017696
Institute for Integration of Medicine & Science: A Partnership to Improve Health

 

Role of Oxidized Linoleic Acid Metabolites in Pain:

The management of pain remains a major medical problem that is due, at least in part, to an incomplete understanding of the physiologic mechanisms for transduction of noxious stimuli. Both pharmacological and gene deletion studies have demonstrated a pivotal role for TRPV1 (transient receptor potential subtype V1) in inflammatory heat hyperalgesia and thermoregulation and this receptor is expressed in a significant proportion of pain-sensing sensory neurons, termed nociceptors. Interestingly, the precise mechanism(s) for the endogenous activation of TRPV1 remains unknown. In this application, we will evaluate the innovative hypothesis that TRPV1 activities are regulated by endogenous oxidized linoleic acid metabolites (OLAMs). Our preliminary data demonstrate that heat evokes the release of linoleic acid metabolites that comprise a new family of physiologically relevant TRPV1 agonists by contributing to the heat responsiveness of this channel. Based upon previous studies and our own results, we propose the central hypothesis that certain peripheral stimuli trigger the release of OLAMs that regulate TRPV1 activities.

Specific Aim #1:  Determine the key enzymatic pathway(s) involved in the generation of OLAM-induced TRPV1 activation in cultured sensory neurons. 

Specific Aim #2:  Evaluate the physiologic relevance of key peripheral enzymatic pathway(s) regulating OLAM-induced TRPV1 activities in control vs inflamed skin biopsies. 

Specific Aim #3:  Evaluate the physiologic relevance of key peripheral enzymatic pathway(s) for regulating inflammatory thermal hyperalgesia/allodynia in vivo. 

   This novel hypothesis may have considerable medical significance since mechanisms inhibiting OLAM synthesis or function may comprise novel targets for analgesic drug development. In addition, the discovery of OLAM regulation of TRPV1 activities provides a novel and previously unknown mechanism for pain transduction that may promote fundamental research into cellular transduction of noxious stimuli as well as research on preclinical pain models ranging from inflammation to neuropathic conditions to cancer-related pain. 

 

Estrogen Modulation of Human Nociceptors:

Clinical studies of multiple pain disorders indicate that a patient’s biological sex is a common risk factor for pain, with many studies demonstrating that women are at increased risk for pain in many acute and chronic conditions. The proposed translational clinical study directly tests the hypotheses that estradiol (17b-E2) increases peripheral nociceptor activity in human acute pain patients and that polymorphisms of the estrogen receptors are associated with increased nociceptor activity and post-operative pain.  To address this hypothesis, we have developed a method for evaluating estradiol enhancement of the exocytotic activity of peripheral human nociceptors innervating surgical biopsies of healthy tissue (evaluating substance P (SP) release from neuron terminals innervating dental pulp from extracted third molar teeth).  Our preliminary studies identified estrogen receptor a (ERa) and ERa in both human trigeminal ganglia neurons and in peripheral neurons in surgical biopsies, and discovered that estradiol significantly increases bradykinin/prostaglandin E2 (BK/PGE2)-evoked iSP from human tissue biopsies collected from women, but not from men. Moreover, in this A1 revision, we report new findings that certain polymorphisms of ERa and ERb are positively correlated with increased intensity of post-operative pain in these patients.  Thus, we have developed a working hypothesis that estrogen sensitizes peripheral terminals of human trigeminal nociceptors.  To evaluate this hypothesis, we propose the following aims:

Specific Aim 1: Determine whether females differ from males for increased release of SP following stimulation with either BK/PGE2 or with capsaicin. 

Specific Aim 2:  Determine whether elevated circulating estradiol levels are associated with increased release of SP following stimulation with either BK/PGE2 or with capsaicin

Specific Aim 3: Determine whether specific polymorphisms of the estrogen receptor alpha (ERa) or beta (ERb) are associated with increased BK/PGE2- or capsaicin-evoked release of SP from surgical biopsies exposed to estradiol. 

Specific Aim 4: Establish a data and gene bank to facilitate future genetic epidemiological and pharmacogenetic studies. This database will be used for three proposed secondary analyses including an evaluation of the association between ER polymorphisms and post-surgical pain and will be also available to other investigators to foster the NIH policy for data sharing.

These integrated studies will evaluate estrogen modulation of peripheral human nociceptors at the pharmacological, biochemical and genetic levels.  Collectively, these studies provide a comprehensive evaluation of the hypothesis that activation of estrogen receptors enhances nociceptor function in women. 

 

Prolactin Modulation of Trigeminal Nociceptors:

The role of gender and pain remains a major health care problem, and in preliminary studies on this topic, we evaluated the long-term effects of estradiol on gene expression in trigeminal neurons.  The results constituted an unexpected discovery that estradiol upregulates prolactin (PRL) more than 40 fold in sensory neurons.  Follow-up studies demonstrated that PRL and the PRL receptors (PRL-R) are expressed in the capsaicin-sensitive neurons of both female and male rats, and that application of capsaicin evokes PRL release from trigeminal sensory neurons.  Furthermore, application of exogenous PRL significantly increases nociceptor responsiveness to capsaicin as measured by inward currents, CGRP exocytosis, accumulation of intracellular calcium levels, and nocifensive behavior. We now provide new studies demonstrating increased PRL levels in CFA inflamed tissue and antihyperalgesic actions of a PRL receptor antagonist.   These preliminary data provide strong initial support for a completely new hypothesis of nociceptor regulation by an autocrine/paracrine system containing PRL.  Based upon this hypothesis, PRL may serve as a novel hyperalgesic agent in both females and in males. We believe that this discovery has substantial scientific and medical implications, and is highly innovative from a conceptual perspective. Therefore, this project will characterize the mechanisms mediating prolactin effects in female and male rats and will directly test the hypotheses that PRL evokes a rapid increase in the responsiveness sensory neurons to noxious stimuli such as capsaicin. Our specific aims will:

Specific Aim 1:  Determine the effects of exogenous PRL on capsaicin- and inflammation-induced hyperalgesia/allodynia. 

Specific Aim 2:  Determine the mechanisms by which PRL rapidly increases the responsiveness of trigeminal neurons to noxious chemical and thermal stimuli. 

Specific Aim 3:  Characterize the stimuli that evoke PRL release in trigeminal sensory neurons from in vitro cultures and from acutely isolated and superfused peripheral terminals.     

The discovery that trigeminal sensory neurons express both PRL and PRLR, and that application of exogenous PRL significantly and rapidly sensitizes trigeminal nociceptors to noxious stimuli such as capsaicin, provides strong initial support for a completely new and innovative hypothesis of nociceptor regulation by an autocrine/paracrine PRL system, and compounds that block the PRL-R may serve as a novel class of analgesic drugs in gender dependent pain.

 

Mechanisms of airway neurogenic inflammation by asthma-inducing allergens:

Asthma is the most common chronic inflammatory disease of the airways. It affects approximately 34.1 million Americans throughout their lifetime, and the number of people with asthma continues to grow. Standard treatment using an inhaled short-acting beta-2 agonist is only effective against acute symptoms. Though avoiding allergens and irritants while utilizing inhaled corticosteroids may help some patients, these preventatives are still ineffective in completely deterring asthma. Furthermore, cases of asthma will have varying responses to the standard treatments available. Accordingly, finding the specific mechanisms for the defined subgroups of asthma that respond well to various types of treatments is a current critical goal of asthma research. Allergens and environmental irritants play a key role in initiation and maintenance of asthma in children and adults. It is well accepted that airway inflammation plays an important role in the development of airway hyperresponsiveness (AHR) in asthmatic patients. Recent evidence demonstrates airway inflammation during asthma in animals and humans may be at least partially neurogenic in nature. This neurogenic inflammation is induced by neuropeptides released from airway innervating C-fibers of sensory neurons with nodose (ND), jugular, and dorsal root (T1-T6) ganglia (DRG) origin. However, the molecular and physiological mechanisms involving allergens and a combination of allergens and environmental irritants inducing neurogenic inflammation of airways are largely unknown. One of the possibilities is that neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP), which trigger neurogenic inflammation, could be released from sensory nerve terminals innervating airways upon stimulation by certain allergens. According to this mechanism, certain allergens would be able to promote neurogenic acute and/or chronic inflammation of the airways. To address this critical question of how exposure to certain allergens results in initiation of neurogenic inflammation of the airways, we hypothesize that certain asthma-inducing mold and house dust mite allergens - DerP1, DerP3&9 and PenC13 - belonging to the protease family initiate inflammation of the airways by activating the sensory neurons innervating these airways and by sensitizing the effects of acrolein and carvacrol (potent tobacco smoke and environmental irritants) on sensory neurons. This conceptually innovative hypothesis which proposes distinct mechanisms of airway inflammation by mold and house dust mite allergens has a strong potential for scientific and medical developments. PUBLIC HEALTH RELEVANCE: The management of asthma represents a major scientific and health care challenge as many of the currently used medications are ineffective in completely deterring asthma or may produce debilitating side effects. Here we propose a novel hypothesis for the initiation of neurogenic inflammation of airways by certain house dust mite and mold asthma-inducing allergens, and by a combination of these allergens and environmental irritants from cigarette smoke, smog and pollution. This conceptually innovative hypothesis has implications for both the scientific and medical fields by expanding our understanding of the role of the peripheral nervous system in initiation of airway inflammation by certain allergens, and by creating a foundation for novel therapeutic strategies aiming to correct the underlying causes of the initiation of asthma by allergens and environmental irritants.

 

MMP Inhibitor for Orofacial Pain:

Evaluates the possible analgesic effects of a novel matrix metalloproteinase (MMP) inhibitor on an animal behavioral model of orofacial neuropathic pain.

 

A New Method to Treat Burn Pain in Our Wounded Warriors

Evaluates the possible analgesic effects of a novel matrix metalloproteinase (MMP) inhibitor on an animal behavioral model of orofacial neuropathic pain.

 

A Novel Approach to Pain Control

We propose to test the hypothesis that drugs that block OLAM production in vitro comprise novel analgesics when tested in preclinical pain models.

 

Institute for Integration of Medicine & Science: A Partnership to Improve Health:

The University of Texas Health Science Center at San Antonio (UTHSCSA) has established the Institute for Integration of Medicine and Science (IIMS) as the home for our Clinical and Translational Science Award (CTSA). Our mission is to achieve optimal integration of clinical and translational research, education, training, and career development across all UTHSCSA schools and among our partner organizations in the South Texas region. IIMS will focus existing and newly developing resources and intellectual capital on advancing the discipline of clinical and translational research for the improvement of human health. Meaningful bidirectional community participation has promoted buy-in from all stakeholders and will remain a key principle as IIMS continues to evolve. IIMS partners have brought together major talent and a broad array of resources to create synergies that add value to all participating organizations, residents of our region and the CTSA network. Key function working groups have developed many innovative approaches to providing optimal support for IIMS investigators and programs. Distinctive features of IIMS include: 1) thriving partnerships with key public and private organizations (academic, health care, public health, military), 2) major investments in research resources and infrastructure, 3) the largest cadre of military health care and biomedical research operations in the US, 4) one of the world’s largest primate research colonies, 5) a 46,000 square mile service area populated by predominantly Hispanic residents comprising some of the country’s poorest people, plagued by high rates of health disparities, providing an opportunity, challenge and obligation for us to make a significant impact on human health. Within the context of our collective resources, community focus, and unique regional demographics, we have identified four Specific Aims as the core elements of our CTSA application:

Aim 1- To support transformative clinical and translational research by providing a comprehensive infrastructure integrated effectively among our partners for the creation of multidisciplinary clinical research teams;

Aim 2- To create the optimal intellectual environment and nurturing atmosphere necessary for the training of future clinical and translational career investigators, building upon existing strengths, partnerships, a diverse trainee pool and strong faculty dedication to mentoring;

Aim 3- To develop community-based models that address the best means for translating research findings, focusing on our unique population-specific risk factors, disease burdens and health disparities;

Aim 4- To implement robust tracking and outcome evaluation systems across all IIMS programs. The mission of IIMS is sharply focused on public health. Indeed, our primary vision is to work closely with all partners to translate the results of our academic and community-based research for the direct benefit of our regional population.

 

Development of Anti-OLAM Aptamers as Novel Analgesics:

Development of Anti-OLAM Aptamers as Novel Analgesics. The management of pain remains a major health care problem due to an incomplete understanding of pain mechanisms. TRPV1, a prominent member of the transient receptor potential (TRP) family of ligand-gated ion channel, detects noxious chemical and physical stimuli in peripheral tissues. Both pharmacological and gene deletion studies have demonstrated a pivotal role for TRPV1 in inflammatory heat hyperalgesia and other pain conditions. Oxidized linoleic acid metabolites (OLAMs) have been recently demonstrated to comprise a novel family of endogenous TRPV1 agonists that contributes to acute and inflammatory pain conditions. Therefore, compounds that block the OLAM system are likely to constitute a novel family of analgesics. In direct support of this prediction, preliminary data provided herein demonstrate that injection of antibodies against two of the major OLAMs, 9-HODE and 13-HODE, produce significant analgesia in two pain models. Although these data provide evidence for proof-of-concept, the clinical development of rabbit polyclonal antibodies is not feasible due to adverse effects related to immunogenicity. Accordingly, Operational Technologies Corporation (OpTech) proposes to use combinatorial aptamer chemistry to discover DNA aptamers that specifically bind to these OLAMs and neutralize their pain-producing activities. This would permit replacing antibodies with more specific, less expensive and perhaps higher affinity DNA aptamers. In Phase 1, OpTech expects to complete two overall Specific Aims.

Aim 1 will develop, clone, and sequence several highly specific DNA aptamers that bind 9-hydroxydecadienoic acid (HODE) and 13-HODE without binding to the precursor lipid, linoleic acid (Fig 1A). Aim 2 will evaluate the analgesic activity of the aptamers using several in vivo preclinical rat models of pain. In Phase 2, OpTech will refine, optimize, and begin commercialization of its anti-OLAM aptamer compounds. The Phase 2 optimization process will include 3-D modeling of putative aptamer binding pocket interactions with the OLAMs. Based on 3-D modeling findings, OpTech anticipates adding modified bases having various functional groups (e.g., primary amines, methyl, thiol groups, etc.) that are now commercially available for addition to oligonucleotides at the point of chemical synthesis. The effects of these additional functional groups on aptamer-OLAM binding affinity are expected to better emulate amino acid side chains and will be studied by ELISA-like plate assays and surface plasmon resonance (SPR). The highest affinity and most specific unmodified or modified anti-OLAM aptamers will move into animal studies. The most effective aptamers in animal pain studies will be modified for longer in vivo lifetimes (3'-cholesterol addition and inclusion in liposomes, PEGylation, etc.) or time-released formulation and enter the FDA approval pipeline. PUBLIC HEALTH RELEVANCE: Development of Anti-OLAM Aptamers as Novel Analgesics Millions of patients suffer from pain and many available analgesic drugs ("pain killers") suffer from either incomplete analgesia or unacceptable side-effects. The proposal will develop a novel class of analgesics that work by blocking the endogenous capsaicin-like substances that are released during tissue injury.