Meharry Medical College is a Historically Black College in Nashville, Tenn., that provides education and training to African American and other minority students in the fields of medicine, dentistry, and graduate biomedical sciences. True to its mission, “Meharry Medical College is an academic health sciences center that exists to improve the health and health care of minority and underserved communities by offering excellent education and training programs in the health sciences. True to its heritage, Meharry places special emphasis on providing opportunities for people of color, individuals from disadvantaged backgrounds, and others regardless of race or ethnicity; delivering high quality health services; and conducting research that fosters the elimination of health disparities”. While about 80% of Meharry’s students are African-American, remaining 20% come from other ethnic/racial groups including Hispanic and Native American. In addition to clinical training, patient care, and service largely to the poor and underserved in Nashville, Meharry faculty members actively play a major role in basic biomedical, behavioral, and clinical research with a strong focus on diseases and conditions that affect underrepresented individuals in the areas of HIV/AIDS, Cancer, Behavioral Health, and Periodontal Diseases. Therefore, in this application we will focus our center’s research on these four areas towards eliminating of health disparities.
While most research at Meharry Medical College occurs in the School of Medicine and School of Graduate Studies and Research, the School of Dentistry is rapidly developing its research enterprise. With the inclusion of a clinical project to define the influence of ethnicity on periodontal disease microbiome, we will promote biomedical and clinical research in the School of Dentistry at Meharry. We envision that the RCMI program will enjoy the active participation of investigators from all three schools at Meharry. Faculty, staff, and students will participate in the RCMI as junior investigators, mentors, or as those using or enabling the facilities and services of our Research Infrastructure Core. Currently, Meharry has 198 full time clinical and basic science faculty, of which about 60% are actively involved in research, while the remainder are purely teaching faculty. Though this program draws most of its strength from the research expertise of Meharry faculty, additional expertise comes from Vanderbilt University Medical Center through collaborations and partnerships created by the Meharry/Vanderbilt Alliance and the Clinical and Translational Science Award (CTSA). In addition, Meharry has a cadre of faculty with research expertise in Community-Based Participatory Research (CBPR), clinical research, and basic science. Meharry’s Research funding is comprehensive and overwhelmingly focuses on health disparities. The School of Graduate Studies and Research grants MHS, MSPH, and PhD degrees, as well as dual degrees in collaboration with the other two schools at Meharry (MD/PhD, DDS/PhD and MS/MSPH). There are five interdisciplinary programs where students may receive a Ph.D. degree in Biomedical Sciences: Biochemistry & Cancer Biology, Microbiology & Immunology, Neurosciences, Physiology and Pharmacology. The programs are interdisciplinary because faculty in one department may train students in more than one program. Faculty from the four research departments at Meharry, other departments, Vanderbilt University Medical Center, and other institutions, constitute the core training faculty. There are five Basic Sciences Departments at Meharry: Professional Education, Biochemistry & Cancer Biology, Microbiology & Immunology, Neurosciences & Pharmacology and Physiology. Whereas faculty in the Division of Professional Education commit at least 80% effort to teaching medical, dental, and post-baccalaureate students, faculty in the research departments commit at least 80% effort to research, and to training and mentoring PhD students. Clinical faculty often have secondary appointments in one of the four research departments and participate in their activities.
Meharry Medical College has significant, national impact on the training of the next generation of Biomedical Scientists, having graduated 281 individuals with PhDs since 1976. Meharry has continued to produce a high number of African-American PhDs. In the past five years, Meharry has been in the top 5 institutions graduating African-American PhDs in Biomedical Sciences; and # 1 in 2015, 42014 and 2012 according to Diverse Issues in Higher Education). These young professionals are well trained in their disciplines, publish extensively in peer-reviewed journals, and many of continued in academic careers, at national research labs (FDA, EPA), or the NIH itself.
Meharry Medical College is one of the charter institutions that successfully competed for the first RCMI awards in 1985. Through the years, the RCMI program has supported Meharry’s research infrastructure in multiple signature research areas including neuroscience, cancer biology, environmental health and toxicology, infectious diseases including HIV/AIDS, and oral biology. The RCMI program has significantly advanced the research enterprise at Meharry. The funding of this proposal will take Meharry Medical College’s legacy of improving the health and health care of minority and underserved communities into the future with unprecedented promise.
The RCMI Program in Health Disparities Research is designed to address health disparities through research in diseases that affect the community it serves, engagement of this community in its solutions, and creating technologies and research infrastructure to serve the institutional scientific community and its academic and community partners. This collaborative approach is critical because finding the right answers to address disparities in health equity involves all of us.
The RCMI Program in Health Disparities Research at Meharry Medical College (RHDR@MMC) proposes to address health disparities at multiples scales of research: from micro to macro environments. With institutional collaboration and support, this application continues the long-term RCMI support of enabling high quality basic, behavioral, and clinical research to eliminate health disparities as our long-term goal. The RHDR@MMC is not discipline or disease focused, but emphasizes the disruption of disparity at all scales, from proteins to the human ecosystems of the populations we serve. Our re-envisioned Research Infrastructure Core will provide expert technical support in areas relevant to the research projects, as well as services such as design, biostatistics, bio and health informatics, and cross-training support to benefit ALL researchers at the institution. We have assembled a cadre of scientists including basic, behavioral, dental clinicians, population-based, and community-engaged researchers at Meharry to participate in this endeavor.
SPECIFIC AIMS OF CURRENT APPLICATION
Our aims are to: 1) Support four outstanding research projects addressing HIV-AIDS, prostate cancer, racial and ethnic differences in periodontal disease microbiomes, and adversity-driven chronic pain to advance fundamental understanding of these health disparities. 2) Strengthen core technologies and expand bioinformatics and biostatistical services supporting the four research projects, as well as all Meharry research faculty, to increase institutional success in extramural funding studying diseases that disproportionally affect minority and other health disparity populations. 3) Nurture an environment conducive to developing new and early career investigators by facilitating a mentorship network, enhancing professional developmental activities, and providing pilot project funds. 4) Improve and expand relationships with community-based organizations that partner with Meharry. 5) Recruit outstanding magnet scientists to energize current faculty and contribute to our research capacity in cancers of the underserved, infectious diseases including HIV-AIDS, disparity-causing differences in microbiomes of minorities, and societal adversity leading to debilitating chronic pain in African Americans.
Our aims will be facilitated by supporting the following cores and components: 1) Administrative Core: The administrative core will provide effective leadership to expand and promote infrastructure supporting innovative research discoveries in health disparities, aligning institutional resources rationally with RHDR@MMC activities. 2) Research Infrastructure Core: The Research Infrastructure Core dramatically reconfigures and re-envisions the shared technical and support infrastructure to consolidate instrumentation, data analytics expertise, and intellectual stimulation across methodological scales and disciplines of approach. 3) Investigator Development Core: The Investigator Development Core will provide funds to generate preliminary data, cultivate mentorship by novel Blue-Sky Committees, and curate innovative combinations of existing professional development resources with novel career advancement networks to optimize the chances of independent funding for post docs and junior investigators pursing health disparity topics. 4) Community-Engagement Core: The Community Engagement Core will expand and promote the engagement of the institution to conduct community-engaged research, as well as expand the use of communication strategies that are sensitive to various literacies, cultural differences and psychosocial factors. 5) Recruitment Core: The Recruitment Core will increase research capacity and leadership by recruiting two additional magnet scientists addressing health disparities
The Administrative Core will focus on ensuring that the resources of the RCMI Program on Health Disparities Research at Meharry Medical College (RHDR@MMC) are appropriately leveraged to contribute to the elimination of health disparities. The Core will facilitate communication among its stakeholders at all levels, internally and externally including the NIMHD.
The Specific Aims of the Core are: 1) To manage the RHDR@MMC resources effectively, maximizing program impact; 2) Ensure efficient administrative oversight and adequate communication between RHDR@MMC cores, the Administrative Core, and NIMHD; 3) Support the activities of the Steering Committee, the Advisory Committee, and implement their recommendations for program improvement; 4) Develop and implement a plan for self-evaluation of short-term and long-term goals including implementation and tracking of program activities; 5) Ensure that research projects stay on track and the scientists progress through developing a grant submission timeline
Integrative and collaborative efforts will guide interaction among all our cores. Its strong and nurturing leadership, guided by our evaluative approaches will contribute to the success of this program and the significant impact and advancement in health disparities research.
Steering Committee: Day-to-day activities of the RCMI will be managed by the PIs and the Sr. RCMI Program Administrator. Members of the Steering Committee will also assist them and provide comprehensive oversight of the program. The Steering Committee will meet monthly and as needed. Advisory Committee (AC): The AC is advisory to the RHDR@MMC. The AC is advisory to the PIs and the entire program. It will hold semi-annual meetings to review structure and progress. At the meetings, Core Directors will provide a progress report of accomplishments, challenges, resource needs, and plans. In addition, the Research Project PIs and pilot grant investigators will present updates on their research findings and progress. The AC will include representatives from target communities (drawn from the CE Core Community Advisory Board), external scientific advisors, and Meharry faculty not directly supported by the RCMI. Prior to the first AC meeting, members will be provided an initial scorecard, with objectives, metrics, benchmarks and milestones of each key activity according to our logic model. This scorecard will be evaluated and updated at each AC meeting.
Research Infrastructure Core
The overarching goal of the research infrastructure core is to provide expert services and resources for the RHDR@MMC research projects submitted as part of the application, the funded pilot projects, and the overall Meharry community. The RCMI program has provided support to several research and support infrastructure cores since its inception in 1985. For instance, the Office of Research Support Services (ORSS), which was created to centralize grant submissions and monitoring of research and contracts at Meharry, was created with support from the RCMI grant in its first year.
Our longstanding RCMI program provides universally accessible equipment, infrastructure and analysis capacity essential to initiate and sustain research projects at Meharry. We intend to continue this support. To address continuity of services and efficiency of resource management, we propose to bring all the supported core equipment & functions into one continuous space. Therefore, we are also requesting funds for renovation.
The goal of the core, which we have termed CRISALIS (Consolidated Research instrumentation, Informatics, Statistics, and Learning Integration Suite) is to provide resources and services synergistically, enhancing the productivity and outcomes of health disparities research and pilot projects supported by the RCMI Program in Health Disparities Research at Meharry Medical College (RHDR@MMC). We will accomplish this goal through the following specific aims: 1) Co-localize and merge three independent cores (Molecular Biology, Morphology, Proteomics), and an animal imaging instrument into the CRISALIS; 2) Expand research services and analysis by continuing to support bioinformatics activity, adding health informatics, and increasing biostatistics support; 3) Centrally manage the CRISALIS to ensure appropriate tracking, billing, and grant attribution by users; 4) Cross-train seven staff scientists and junior faculty broadly to provide continuous and uninterrupted service; 5) Renovate 5,000 sq. ft. of space to accommodate the specialized scientific instruments and personnel.
Investigator Development Core
This core will address the development of early career investigators in basic biomedical, behavioral, and clinical research through a pilot project program that allows researchers to generate preliminary data for submission of grant applications particularly focusing on research related to diseases that disproportionally impact minority or other disparity populations, or those that address health disparities. Professional development opportunities to increase the participation, advancement, and leadership capabilities of junior faculty and post-doctoral fellows will be linked to this core. Our primary objective is to ensure that resources for robust research career development are available to all junior faculty and post-doctoral fellows. To accomplish this, existing development programs (see Administrative Core) will be curated with novel options to create a holistic, individualized, and rigorous track for each participant. This will include an MOU (memorandum of understanding) indicating that the supported investigator will commit to the development plan and work with a mentorship Blue-Sky Committee. This core will formalize a mentor-mentee relationship for each junior scientist, and will establish an interdisciplinary model that could be modified for other academic medical centers. Central to this model and the success of junior investigators will be their ability to apply for and receive pilot research funding.
The specific aims of this core are to: 1) Establish a pilot awards program targeted to post-doctoral fellows and junior faculty to advance basic, behavioral, and clinical research in health disparities; 2) Mentor the pilot project investigators to enhance their career development, publications, and research outcomes derived from pilot research funds; 3) Implement a grant submission timeline for extramural grant funding appropriate to pilot investigator career stage. Meharry Medical College is in a unique position to help eliminate health disparities. With an institutional foundation built on mission, location in an area of great need (North Nashville), 141 years of serving low-income, largely minority populations, and training minorities for healthcare and biomedical professions, this core will launch creative, collaborative, and innovative research, accelerating discoveries to elevate the vulnerable out of health disparity. Findings from the proposed health disparities pilot research program will to lead to new K, R, and equivalent extramural grants, and will contribute to healthier communities across the nation.
Community Engagement Core
Engaging communities in research is critical for reducing and, in time, eliminating health disparities among racial and ethnic minorities, and socioeconomically disadvantaged communities. The known benefits of this engagement include enhanced research study designs, expansion of public trust in research, increased community research participation, and improved uptake and translation of research findings that are relevant for disparate populations. Cultivating and sustaining meaningful community involvement in research, however, remains one of the most significant challenges facing clinical and behavioral research programs. Guided by leaders with substantial experience in community engaged research, public health, and clinical research, the Community Engagement Core will employ an inclusive and participatory engagement philosophy to involve disparate communities in all aspects of the health disparities research at Meharry Medical College.
A conceptual framework that recognizes the structural, social, cultural, behavioral, and biological factors that influence disparities will guide the Community Engagement Core’s implementation of 3 specific aims: 1) Meaningfully engage community-based organizations in all aspects of the health disparities research including priority-setting, study conduct, and dissemination to address their health-related concerns; 2) Promote community participation in research and catalyze recruitment and retention of underrepresented groups as research participants; 3) Enhance dissemination of health disparities research findings to community stakeholders using culturally-relevant strategies.
In implementing these aims, the Community Engagement Core strives to equip and empower community based organizations to both lead and partner on efforts to address health disparities, increase and enhance the pipeline of community engaged researchers at Meharry Medical College, and inform the field on best practices for engaging communities in efforts to eliminate health disparities.
The goal of the Recruitment Core is to recruit and hire committed health disparities basic, clinical or behavioral researchers in order to support Meharry Medical College’s research vision of developing real solutions to conditions disproportionally affecting minority populations. The Recruitment Core will leverage our Research Endowment Funds, the Investigator Development and the Administrative Cores of this proposal in order to continue to advance disparities research at Meharry.
The Recruitment Core will be implemented through the following specific aims: 1) Hire two independent mid-career or senior scientists to provide additional mentorship; 2) Together with the RCMI faculty team, mentor junior faculty and senior post-docs in health disparities research
Retention of the recruited faculty will be supported by careful attention and support for their research leveraging funds from this core. Additionally the senior faculty will benefit from a robust Research Infrastructure Core including a Biostatistics Core as well as a strong Community Engagement Core. We are confident that we will recruit faculty members with high caliber who will be attracted by our mission and are committed to join us to address health disparities research.
Project 1: Mechanism and oncogenic role of lysine demethylase KDM5B in prostate cancer (Dr. Zhenbang Chen)
Prostate cancer (PCa) is the leading life-threatening malignancy in American men. Unfortunately, the incidence and mortality of PCa are disproportionally higher in African American (AA) males compared with other ethnic populations. It is known that PCa is driven by dysregulation of multiple oncogenic pathways involving both genetic and epigenetic alterations. PTEN (phosphatase and tensin homolog deleted on chromosome 10) is frequently deleted and/or mutated in human cancers including PCa. Loss of PTEN results in invasive PCa in mice, due to aberrant regulations of AKT-mTOR, SKP2, TGF-β, and androgen receptor (AR) signaling, which collectively promote cancer progression. KDM5B (lysine demethylase 5B, also named JARID1B) is a Jumonji C domain-containing H3K4 histone demethylase, and its levels are frequently elevated in human cancers including advanced PCa. We have demonstrated that KDM5B levels in PCa cells are regulated by SKP2 and TRAF6 through ubiquitination. Our preliminary studies revealed that KDM5B elevation is higher in African American (AA) PCa samples than that in Caucasian American (CA) PCa samples. KDM5B levels are strikingly elevated in both prostate tumors of Pten mice and recurrent tumors of Pten/Trp53 mice. The evidence strongly supports the oncogenic roles of KDM5B and epigenetic alterations on castration resistant prostate cancer (CRPC). In this proposal, we hypothesize that KDM5B elevation and its network are essential for prostate tumorigenesis, and KDM5B inactivation will suppress PCa progression. We propose to test this hypothesis by studying the role of KDM5B in prostate tumorigenesis using genetically-engineered mouse models, the molecular mechanism of KDM5B and chromatin modifications in PCa cells, and the impact of KDM5B inhibition on the suppression of prostate tumor growth and PCa disparities. Our
Specific Aims are: 1) Investigate the role of KDM5B on PTEN-null driven prostate tumorigenesis. Both PTEN loss and KDM5B elevation are frequently found in human PCa specimens. PTEN loss results in PCa, and the increased levels of KDM5B are associated with advanced cancers and drug resistance. Prostate tumorigenesis in Pten deficient mice can be accelerated by additional oncogenic insults through bypassing senescence or be suppressed by an abrogation of oncogenic insults through enhancing senescence. Cellular senescence plays a crucial role in tumorigenesis in vivo. Our preliminary data showed that Pten loss aberrantly upregulated KDM5B (the demethylase of H3K4me3/2) in cultured mouse cells and in prostate tumors. In this aim, we will investigate the novel role of KDM5B in prostate tumorigenesis and its crosstalk with the PTEN-AKT, EZH2, and FOXA1-AR pathways in PCa in vivo. We will generate a novel Pten/Kdm5b (PtenLoxP/LoxP; Kdm5bLoxP/LoxP; PBCre4) mouse model to evaluate the impact of Kdm5b deficiency on Pten-deficient prostate tumorigenesis and furthermore histone modifications in vivo; 2) Define the molecular mechanisms of KDM5B signaling network in prostate cancer. KDM5B regulates gene transcription and cell development in addition to its demethylation of H3K4me3/2 to H3K4me1. KDM5B levels are markedly elevated in many cancers including PCa. Dysregulation of the PTEN-PI3K-AKT pathway contributes to an aberration of histone modifications that fuels tumorigenesis. We recently reported that, in a PTEN null context, KDM5B levels were regulated by SKP2, suggesting a novel network of PTENSKP2-KDM5B in PCa cells. We demonstrated that KDM5B ubiquitination is critical for its protein trafficking in the nucleus. In this aim, we will investigate molecular mechanism(s) of KDM5B regulation and its network with SKP2, EZH2, HDAC4, and LSD1 on chromatin modifications, which ultimately affects FOXA1-AR signaling in PCa progression and PCa disparities; 3). Determine the effects of KDM5B inhibition on the suppression of prostate cancer. Pten mouse model with 100% penetrance of PCa provides a valuable preclinical tool to study the mechanism leading to PCa growth, and to evaluate new therapeutic strategies to stop PCa. Our preliminary data showed that KDM5B levels are elevated in prostate tumors of Pten mice, and that KDM5B knockout (KO) with CRISPR/Cas9 decreased the proliferation of PCa cells as compared with controls. In this aim, we will investigate the anticancer effects of KDM5B inhibition with small molecules inhibitors (as well as KDM5B KO) on the proliferation and invasion of AA PCa cells and CA PCa cells. Furthermore, we will examine the impact of KDM5B inhibition on the suppression of PCa tumor growth of humanized xenografts (with AA and CA PCa cells) in athymic mice (immunocompromised) and Luc/Pten mutant mice (immunocompetent). Impact: The results will provide valuable insights into key molecular mechanisms on histone modifications in PCa. Our findings will provide a scientific foundation for development of an effective therapeutic strategy to control PCa, ultimately reducing PCa disparities.
Project 2: Examining the role of cellular miRNAs in HIV-1 Replication (Dr. CV Dash)
In the US, an estimated 1.2 million people are living with HIV. In spite of considerable progress, antiretroviral therapy (ART) remains the only treatment option. The long-term success of ART is dependent on identification of new drugs against novel therapeutics. The anti-viral activity of cellular miRNAs is an emerging area and has a great potential to identify novel therapeutic targets. miRNAs are small noncoding RNAs that negatively regulate gene expression by binding to the 3’ untranslated region (UTR) of target mRNAs causing translational repression or mRNA degradation. miRNAs play fundamental roles in every aspect of cellular process including anti-viral responses. Published data demonstrate that cellular miRNAs regulate replication of many viruses including Primate foamy virus, Hepatitis C virus, Epstein Barr virus, Influenza virus and HIV. The goal of this application is to dissect the mechanism by which cellular miRNAs confer anti-HIV activity. The anti-HIV-1 activity of cellular miRNAs was first discovered by target prediction coupled with experimental validation. Since then several cellular miRNAs has been reported to inhibit HIV-1. Two mechanisms are proposed for the anti-HIV activities of cellular miRNAs. They can bind to HIV-1 transcripts and directly inhibit viral protein translation. Alternatively, they can bind to cellular transcripts and inhibit translation of host factors associated with viral replication. However, there are key knowledge gaps in the understanding of miRNA-mediated anti-HIV activity. Our studies are designed to narrow this knowledge gap by using cocaine as a probe, since cocaine downregulates the anti-HIV miRNAs “miR-125b, miR-150, and miR-28-5p”. Our studies suggest that the promoters of these miRNAs contain DNA methylation sites and methylation of the antiHIV miRNA promoter inhibits transcription. Notably, our preliminary data illustrate that over-expression of DNA methyltransferases (DNMTs) – the enzymes that carry out promoter methylation, induces methylation of antiHIV miRNA promoter. Thus, we hypothesize that anti-HIV-1 miRNAs inhibit HIV-1 by repressing viral protein translation and regulation of anti-HIV miRNAs is dependent on DNMT-assisted promoter hyper methylation.
We will test the hypothesis through the following three specific aims: 1) To determine that repression of HIV-1 translation is mediated by direct binding of anti-HIV miRNAs to viral transcripts. Our data show that cocaine downregulates the anti-HIV-1 miRNAs “miR-125b, miR-150, and miR-28-5p” in primary monocyte-derive macrophages (MDMs) and “miR-125b” in primary CD4+ T cells. Published data suggest that the target sites of these miRNAs are located in the HIV-1 genome. However, the genetic determinants that mediate binding of anti-HIV miRNAs to HIV-1 transcripts and implications of this binding on HIV-1 replication are unknown. Therefore, we will: a) functionally map HIV-1 genome to identify the target sequence(s) of anti-HIV miRNAs by mutational studies, and b) examine the effects of anti-HIV miRNA expression on HIV-1 protein translation, virion release and infectivity using miR-null and -overexpressing cells; 2) To test that DNMT-induced promoter hyper-methylation regulates anti-HIV miRNA expression. DNA methyltransferases (DNMT1, 3a, and 3b) methylate the CpG regions of gene promoters to regulate cellular gene expression. Notably, our data show that upregulation of “DNMT1 and DNMT3a” in primary MDMs and “DNMT1” in primary CD4+ T cells correlates with downregulation of respective anti-HIV miRNAs in these cells. Further analysis reveal that the promoters of miR-125b, miR-150 and miR-28-5p contain CpG-rich methylation sites that are targets for the DNMTs. Thus, we hypothesized that DNMTs are the key regulators of anti-HIV miRNA expression. We will test this by: a) examining the effects of DNMT expression (knock-down and over-expression) on anti-HIV miRNA promoter methylation and promoter activity, and b) demonstrating that DNMT-mediated promoter-methylation regulates anti-HIV miRNA expression; 3) To elucidate the mechanism by which CpG hyper-methylation causes downregulation of anti-HIV-1 miRNAs: The regulatory sequences and the transcriptional regulators of anti-HIV miRNAs are not fully characterized. Our bioinformatics analyses reveal that promoters of miR-125b, miR-150 and miR-28-5p have the binding site for the transcription factor “NF-kB” upstream of the CpG rich regions. We and others have shown that CpG methylation stalls nucleoprotein complexes. Thus, we hypothesize that promoter-methylation inhibits NF-kB-mediated transcription from anti-HIV miRNA promoters. We will elucidate the biochemical basis of transcriptional regulation by: a) examining whether anti-HIV miRNA promoter-methylation reduces NF-kB binding affinity in cell-based and in vitro systems, and b) demonstrating whether promoter methylation inhibits NF-kB-driven transcription of anti-HIV miRNAs in macrophages and CD4+ T cells by genetic analysis. Data generated through this proposal may identify novel targets to inhibit HIV and cellular pathways that can be targeted for therapeutic intervention of HIV-1 patients. Moreover, these anti-HIV miRNAs have been proposed to regulate HIV-1 latency- a high priority HIV/AIDS Research Area designated by NIH. Therefore, our proposed studies are highly significant and transformative in nature.
Project 3: Mechanisms Linking Adversity and Pain in African American Adults (Dr. Matthew Morris)
Chronic pain is a major public health challenge, affecting more adults in the United States than heart disease, cancer and diabetes combined and resulting in over $600 billion annually in medical treatment costs and lost productivity.1 African-American (AA) adults are disproportionately affected by acute and chronic pain and report higher pain severity and greater pain-related disability across a variety of conditions (e.g., AIDS, arthritis, and headache).2,3 Compared to non-minorities with similar pain conditions, AA adults have poorer physical functioning, greater impairment at work and home, and lower quality of life.4-6 Daily bodily pain is common7,8 and often a precursor to chronic pain. Prospective evidence suggests that 14%– 50% of adults experience daily pain,9-11 which is associated with increased risk for chronic pain onset.12-14 Over 12 months, 7%–22% of adults with daily pain will develop chronic low back,15 widespread,16 or musculoskeletal pain.17 Understanding the mechanisms that contribute to daily pain severity and impairment in AA adults is critical for prevention efforts targeting vulnerable adults before they develop debilitating and difficult-to-treat chronic pain conditions. Daily pain is more likely to become chronic in adults who have experienced adversity.1 Compared to non-minorities, AA adults report greater exposure to childhood trauma, family adversity, interpersonal violence, and racial discrimination.18-28 Thus, AA adults are impacted by disparities in risk factors for pain (adversity) and by chronic pain itself. Although the mechanisms linking adversity to daily pain in AA adults have not been clearly delineated, two promising pathways involve alterations of stress response systems (i.e., hypothalamic-pituitary-adrenal [HPA] axis) and pain sensitivity.1 The HPA axis plays an important role in stress-induced analgesia29,30 and may account, in part, for the relation between adversity and pain. Chronic and traumatic stressors are associated with diminished cortisol secretion (Fig.1, path a).31,32 In turn, lower cortisol levels predict higher subsequent pain severity.33 Hair cortisol concentration (HCC) offers a unique temporal perspective on the stress response, reflecting aggregated HPA activity over months.34 Preliminary data from individuals without chronic pain who varied in their exposure to adversity show an association between low HCC and greater sensory and affective pain, as well as worse impairment at work/school and in family life (Fig.1, path b). Despite theoretical models implicating hypocortisolism as a consequence of adversity and a risk factor for persistent pain, 35, 36 to our knowledge, no studies have investigated HPA function as a mechanism linking adversity to pain in AA adults. Experimental pain responses distinguish adults with and without chronic pain, correlate with clinical pain intensity, and predict future risk for developing pain.37 Exposure to early adversity is associated with an experimental index of heightened central sensitization (temporal summation of second pain [TSSP]) in individuals with chronic pain (Fig.1, path c).38 Moreover, prospective studies show that greater TSSP39 and impaired conditioned pain modulation (CPM)40 predict development of chronic pain (Fig.1, path d). Although racial differences in experimental pain responses are well-documented41 and suggest greater TSSP42 and impaired CPM43 in AA compared to non-minority adults, to our knowledge, no studies have assessed altered experimental pain sensitivity as a mechanism linking adversity to pain in AA adults. Overview. We will recruit 160 participants (~50% female) 18–45 years of age, without chronic pain, who self-identity as AA. Assessments at baseline (T1), 6 months (T2) and 12 months (T3) will determine exposure to adversity (self-report, clinical interview, geocoded crime report data), daily pain (intensity/disability), HCC over the previous 3 months (hair samples), and experimental pain facilitation (TSSP) and inhibition (CPM).
Specific Aim 1. Determine whether HPA hypoactivity mediates the relation of adversity to daily pain in AA adults. Multilevel models (MLM) will test HCC as a mediator of the relation between adversity (composite of developmental, contextual, and individual factors) and daily pain over a 12-month period. Hypothesis 1: ↓T2 HCC mediates the relation of ↑T1 adversity to ↑T3 daily pain. Specific Aim 2. Determine whether evoked pain sensitivity mediates the relation of adversity to daily pain in AA adults. We will use MLM to test pain facilitation and pain inhibition as mediators of the relation between adversity and daily pain over a 12-month period. Hypothesis 2A: ↑T2 TSSP mediates the relation of ↑T1 adversity to ↑T3 daily pain. Hypothesis 2B: ↓T2 CPM mediates the relation of ↑T1 adversity to ↑T3 daily pain. Impact. Anticipated findings will highlight two novel mechanistic pathways linking cumulative adversity, which is more common in AA adults, to subsequent daily pain and disability. This proposal will also set the stage for secondary prevention efforts aimed at eliminating racial disparities in chronic pain by identifying HPA hypoactivity and evoked pain sensitivity as early risk markers for screening and potential targets for intervention.
Project 4: Impact of prevalence of P. gingivalis and S. cristatus in oral health disparities (Dr. Hua Xie)
Periodontal infections are the most common inflammatory processes worldwide. Recent studies based on the 2009-2010 NHANES (National Health and Nutrition Examination Survey) data demonstrated that the incidence of periodontitis is significantly higher in African Americans (AAs, 58.6%) and Hispanic Americans (HAs, 59.7%) compared to European Americans (EAs, 42.6%) (1). This was true even after correcting for co-morbid factors in the previous studies. Periodontitis may also have systemic health consequences leading to conditions such as cardiovascular disease, diabetes, and preterm birth, all of which are also considered health disparities in AAs and HAs. Microbiome is recently considered to be an important contributor to these health disparity diseases and conditions (2, 3). This proposed project is designed to examine those factors, with emphasis on individual’s bacterial profile that may contribute to the genesis of periodontitis, an apparent oral health disparity. A systemic understanding of risk factors for disease initiation and progression would be highly significant from a health disparity standpoint.
Dental plaque is a multispecies biofilm, and over 30 genera representing more than 700 species of bacteria have been found in this ecological environment. The latest model of periodontal pathogenesis is that periodontal disease is initiated by a synergistic and dysbiotic microbial community rather than by a select few bacteria traditionally known as periopathogens. Low-abundance bacteria with community-wide effects that are critical for the development of dysbiosis are now known as keystone pathogens, the best-documented example of which is Porphyromonas gingivalis (4). Evidence is accumulating that some early colonizers of dental plaque provide a favorable environment for P. gingivalis, thus facilitating its retention and multiplication, which ultimately leads to a dysbiotic microbial community. Therefore, individuals susceptible to periodontitis may depend to some extent on the microbial composition of the early plaque biofilm.
We were the first to report an antagonistic relationship between Streptococcus cristatus and P. gingivalis (5). A surface protein of S. cristatus, arginine deiminase (ArcA), was identified as the signaling molecule to which P. gingivalis responds by repressing the expression of the fimA gene and production of FimA (6, 7). We also found that the expression of arcA was significantly higher in S. cristatus than in S. gordonii, an oral species known as a helper of P. gingivalis attachment on oral biofilm (8), suggesting a different role of these two streptococcal species in the highly orchestrated formation of dental plaque. We further showed that S. cristatus ArcA interfered with the colonization and pathogenesis of P. gingivalis in vivo, using a mouse model (9). Finally, preliminary results from our laboratory on 13 subjects with periodontitis demonstrated that there appeared to be an inverse relationship between the number of S. cristatus versus P. gingivalis cells in dental plaque, suggesting that S. cristatus may be beneficial to the host by antagonizing the colonization and accumulation of P. gingivalis (10).
In this proposal, we will take advantage of our position as an HBCU and our collaborations with research intensive-institutions to characterize in detail those risk factors involved in the reported disproportionate distribution of periodontitis among AA, EA, and HA populations. Our hypothesis is that different ratios of P. gingivalis and S. cristatus is correlated with initiation and development of periodontitis.
Therefore, using samples from AA, HA, and EA subjects, we propose to: 1) Determine the prevalence and level of S. cristatus versus P. gingivalis in the oral cavities of periodontally healthy individuals, and the association between other potential periodontal risk factors, such as diet, smoking and/or oral hygiene behaviors and the prevalence of S. cristatus vs. P. gingivalis in AA, EA, and HA adults; 2) Compare the prevalence and progression of S. cristatus versus P. gingivalis in AA, EA, and HA adults with periodontitis, before and after periodontal treatments; 3) Investigate if intense education of periodontal health will promote a shift in ratio of S. cristatus versus P. gingivalis in periodontitis patients. The studies proposed here are built on novel findings of our bench studies regarding an antagonistic relationship between Streptococcus cristatus and P. gingivalis. Completion of the proposed clinical studies may close the knowledge gaps on why periodontitis more often affects AAs and HAs and why AAs have worse periodontitis. Moreover, identification of a strong correlation between the ratio of these two bacteria and periodontitis may lead to development of a simple and rapid biochemical marker for the prognosis of periodontitis and to discovery of compounds that are able to change the ratio of these bacteria.