Development and Implementation of an Integrated Preclinical Atherosclerosis Database

BACKGROUND

Basic scientists have used preclinical animal models to explore mechanisms driving human diseases for decades, resulting in thousands of publications, each supporting causative inferences. Despite substantial advances in the mechanistic construct of disease, there has been limited translation from individual studies to advances in clinical care. An integrated approach to these individual studies has the potential to improve translational success.

METHODS

Using atherosclerosis as a test case, we extracted data from the 2 most common mouse models of atherosclerosis (ApoE [apolipoprotein E]-knockout and LDLR [low-density lipoprotein receptor]-knockout). We restricted analyses to manuscripts published in 2 well-established journals, Arteriosclerosis, Thrombosis, and Vascular Biology and Circulation, as of query in 2021. Predefined variables including experimental conditions, intervention, and outcomes were extracted from each publication to produce a preclinical atherosclerosis database.

RESULTS

Extracted data include animal sex, diet, intervention type, and distinct plaque pathologies (size, inflammation, and lipid content). Procedures are provided to standardize data extraction, attribute interventions to specific genes, and transform the database for use with available transcriptomics software. The database integrates hundreds of genes, each directly tested in vivo for causation in a murine atherosclerosis model. The database is provided to allow the research community to perform integrated analyses that reflect the global impact of decades of atherosclerosis investigation.

CONCLUSIONS

This database is provided as a resource for future interrogation of sub-data sets associated with distinct plaque pathologies, cell type, or sex. We also provide the methods and software needed to expand this data set and apply this approach to the extensive repository of peer-reviewed data utilizing preclinical models to interrogate mechanisms of diverse human diseases.

Session Introduction: Drug-repurposing and discovery in the era of "big" real-world data: how the incorporation of observational data, genetics, and other -omic technologies can move us forward

This PSB 2024 session discusses the many broad biological, computational, and statistical approaches currently being used for therapeutic drug target identification and repurposing of existing treatments. Drug repurposing efforts have the potential to dramatically improve the treatment landscape by more rapidly identifying drug targets and alternative strategies for untreated or poorly managed diseases. The overarching theme for this session is the use and integration of real-world data to identify drug-disease pairs with potential therapeutic use. These drug-disease pairs may be identified through genomic, proteomic, biomarkers, protein interaction analyses, electronic health records, and chemical profiling. Taken together, this session combines novel applications of methods and innovative modeling strategies with diverse real-world data to suggest new pharmaceutical treatments for human diseases.

Whole genome sequence analysis of apparent treatment resistant hypertension status in participants from the Trans-Omics for Precision Medicine program

Introduction: Apparent treatment-resistant hypertension (aTRH) is characterized by the use of four or more antihypertensive (AHT) classes to achieve blood pressure (BP) control. In the current study, we conducted single-variant and gene-based analyses of aTRH among individuals from 12 Trans-Omics for Precision Medicine cohorts with whole-genome sequencing data. Methods: Cases were defined as individuals treated for hypertension (HTN) taking three different AHT classes, with average systolic BP ≥ 140 or diastolic BP ≥ 90 mmHg, or four or more medications regardless of BP (n = 1,705). A normotensive control group was defined as individuals with BP < 140/90 mmHg (n = 22,079), not on AHT medication. A second control group comprised individuals who were treatment responsive on one AHT medication with BP < 140/ 90 mmHg (n = 5,424). Logistic regression with kinship adjustment using the Scalable and Accurate Implementation of Generalized mixed models (SAIGE) was performed, adjusting for age, sex, and genetic ancestry. We assessed variants using SKAT-O in rare-variant analyses. Single-variant and gene-based tests were conducted in a pooled multi-ethnicity stratum, as well as self-reported ethnic/racial strata (European and African American). Results: One variant in the known HTN locus, KCNK3, was a top finding in the multi-ethnic analysis (p = 8.23E-07) for the normotensive control group [rs12476527, odds ratio (95% confidence interval) = 0.80 (0.74-0.88)]. This variant was replicated in the Vanderbilt University Medical Center's DNA repository data. Aggregate gene-based signals included the genes AGTPBP, MYL4, PDCD4, BBS9, ERG, and IER3. Discussion: Additional work validating these loci in larger, more diverse populations, is warranted to determine whether these regions influence the pathobiology of aTRH.

Genetic examination of hematological parameters in SARS-CoV-2 infection and COVID-19

People hospitalized with COVID-19 often exhibit altered hematological traits associated with disease prognosis (e.g., lower lymphocyte and platelet counts). We investigated whether inter-individual variability in baseline hematological traits influences risk of acute SARS-CoV-2 infection or progression to severe COVID-19. We report inconsistent associations between blood cell traits with incident SARS-CoV-2 infection and severe COVID-19 in UK Biobank and the Vanderbilt University Medical Center Synthetic Derivative (VUMC SD). Since genetically determined blood cell measures better represent cell abundance across the lifecourse, we also assessed the shared genetic architecture of baseline blood cell traits on COVID-19 related outcomes by Mendelian randomization (MR) analyses. We found significant relationships between COVID-19 severity and mean sphered cell volume after adjusting for multiple testing. However, MR results differed significantly across different freezes of COVID-19 summary statistics and genetic correlation between these traits was modest (0.1), decreasing our confidence in these results. We observed overlapping genetic association signals between other hematological and COVID-19 traits at specific loci such as MAPT and TYK2. In conclusion, we did not find convincing evidence of relationships between the genetic architecture of blood cell traits and either SARS-CoV-2 infection or COVID-19 hospitalization, though we do see evidence of shared signals at specific loci.

Next-generation phenotyping: introducing phecodeX for enhanced discovery research in medical phenomics

MOTIVATION

Phecodes are widely used and easily adapted phenotypes based on International Classification of Diseases codes. The current version of phecodes (v1.2) was designed primarily to study common/complex diseases diagnosed in adults; however, there are numerous limitations in the codes and their structure.

RESULTS

Here, we present phecodeX, an expanded version of phecodes with a revised structure and 1,761 new codes. PhecodeX adds granularity to phenotypes in key disease domains that are under-represented in the current phecode structure-including infectious disease, pregnancy, congenital anomalies, and neonatology-and is a more robust representation of the medical phenome for global use in discovery research.

AVAILABILITY AND IMPLEMENTATION

phecodeX is available at https://github.com/PheWAS/phecodeX.

Development and implementation of an integrated preclinical atherosclerosis database

Background

Basic scientists have used preclinical animal models to explore mechanisms driving human diseases for decades, resulting in thousands of publications, each supporting causative inferences. Despite substantial advances in the mechanistic construct of disease, there has been limited translation from individual studies to advances in clinical care. An integrated approach to these individual studies has the potential to improve translational success.

Methods

Using atherosclerosis as a test case, we extracted data from the two most common mouse models of atherosclerosis (ApoE and LDLR knockout). We restricted analyses to manuscripts published in two well-established journals, Arteriosclerosis, Thrombosis, and Vascular Biology and Circulation, as of query in 2021. Predefined variables including experimental conditions, intervention and outcomes were extracted from each publication to produce a preclinical atherosclerosis database.

Results

Extracted data include animal sex, diet, intervention type and distinct plaque pathologies (size, inflammation, lipid content). Procedures are provided to standardize data extraction, attribute interventions to specific genes and transform the database for use with available transcriptomics software. The database integrates hundreds of genes, each directly tested in vivo for causation in a murine atherosclerosis model. The database is provided to allow the research community to perform integrated analyses that reflect the global impact of decades of atherosclerosis investigation.

Conclusions

Future database uses include interrogation of sub-datasets associated with distinct plaque pathologies, cell-type or sex. We provide the methods and software needed to apply this approach to the extensive repository of peer-reviewed data utilizing preclinical models to interrogate mechanisms of diverse human diseases.

A genetically supported drug repurposing pipeline for diabetes treatment using electronic health records

BACKGROUND

The identification of new uses for existing drug therapies has the potential to identify treatments for comorbid conditions that have the added benefit of glycemic control while also providing a rapid, low-cost approach to drug (re)discovery.

METHODS

We developed and tested a genetically-informed drug-repurposing pipeline for diabetes management. This approach mapped genetically-predicted gene expression signals from the largest genome-wide association study for type 2 diabetes mellitus to drug targets using publicly available databases to identify drug-gene pairs. These drug-gene pairs were then validated using a two-step approach: 1) a self-controlled case-series (SCCS) using electronic health records from a discovery and replication population, and 2) Mendelian randomization (MR).

FINDINGS

After filtering on sample size, 20 candidate drug-gene pairs were validated and various medications demonstrated evidence of glycemic regulation including two anti-hypertensive classes: angiotensin-converting enzyme inhibitors as well as calcium channel blockers (CCBs). The CCBs demonstrated the strongest evidence of glycemic reduction in both validation approaches (SCCS HbA1c and glucose reduction: -0.11%, p = 0.01 and -0.85 mg/dL, p = 0.02, respectively; MR: OR = 0.84, 95% CI = 0.81, 0.87, p = 5.0 x 10-25).

INTERPRETATION

Our results support CCBs as a strong candidate medication for blood glucose reduction in addition to cardiovascular disease reduction. Further, these results support the adaptation of this approach for use in future drug-repurposing efforts for other conditions.

FUNDING

National Institutes of Health, Medical Research Council Integrative Epidemiology Unit at the University of Bristol, UK Medical Research Council, American Heart Association, and Department of Veterans Affairs (VA) Informatics and Computing Infrastructure and VA Cooperative Studies Program.

Patient-Reported Functional Impairment Due to Hearing Loss and Tinnitus After Cisplatin-Based Chemotherapy

PURPOSE

Cisplatin is widely used and highly ototoxic, but patient-reported functional impairment because of cisplatin-related hearing loss (HL) and tinnitus has not been comprehensively evaluated.

PATIENTS AND METHODS

Testicular cancer survivors (TCS) given first-line cisplatin-based chemotherapy completed validated questionnaires, including the Hearing Handicap Inventory for Adults (HHIA) and Tinnitus Primary Function Questionnaire (TPFQ), each of which quantifies toxicity-specific functional impairment. Spearman correlations evaluated associations between HL and tinnitus severity and level of functional handicap quantified with the HHIA and TPFQ, respectively. Associations between HL or tinnitus and five prespecified adverse health outcomes (cognitive dysfunction, fatigue, depression, anxiety, and overall health) were evaluated.

RESULTS

HL and tinnitus affected 137 (56.4%) and 147 (60.5%) of 243 TCS, respectively. Hearing aids were used by 10% TCS (14/137). Of TCS with HL, 35.8% reported clinically significant functional impairment. Severe HHIA-assessed functional impairment was associated with cognitive dysfunction (odds ratio [OR], 10.62; P < .001), fatigue (OR, 5.48; P = .003), and worse overall health (OR, 0.19; P = .012). Significant relationships existed between HL severity and HHIA score, and tinnitus severity and TPFQ score (P < .0001 each). TCS with either greater hearing difficulty or more severe tinnitus were more likely to report cognitive dysfunction (OR, 5.52; P = .002; and OR, 2.56; P = .05), fatigue (OR, 6.18; P < .001; and OR, 4.04; P < .001), depression (OR, 3.93; P < .01; and OR, 3.83; P < .01), and lower overall health (OR, 0.39; P = .03; and OR, 0.46; P = .02, respectively).

CONCLUSION

One in three TCS with HL report clinically significant functional impairment. Follow-up of cisplatin-treated survivors should include routine assessment for HL and tinnitus. Use of the HHIA and TPFQ permit risk stratification and referral to audiologists as needed, since HL adversely affects functional status and is the single largest modifiable risk factor for cognitive decline and dementia in the general population.

Comprehensive association analysis of speech recognition thresholds after cisplatin-based chemotherapy in survivors of adult-onset cancer

PURPOSE

Deficits in speech understanding constitute one of the most severe consequences of hearing loss. Here we investigate the clinical and genetic risk factors for symmetric deterioration of speech recognition thresholds (SRT) among cancer survivors treated with cisplatin.

METHODS

SRT was measured using spondaic words and calculating the mean of measurements for both ears with symmetric SRT values. For clinical associations, SRT-based hearing disability (SHD) was defined as SRT≥15 dB hearing loss and clinical variables were derived from the study dataset. Genotyped blood samples were used for GWAS with rank-based inverse normal transformed SRT values as the response variable. Age was used as a covariate in association analyses.

RESULTS

SHD was inversely associated with self-reported health (p = 0.004). Current smoking (p = 0.002), years of smoking (p = 0.02), BMI (p < 0.001), and peripheral motor neuropathy (p = 0.003) were positively associated with SHD, while physical activity was inversely associated with SHD (p = 0.005). In contrast, cumulative cisplatin dose, peripheral sensory neuropathy, hypertension, and hypercholesterolemia were not associated with SHD. Although no genetic variants had an association p value < 5 × 10-8 , 22 genetic variants were suggestively associated (p < 10-5 ) with SRT deterioration. Three of the top variants in 10 respective linkage disequilibrium regions were either positioned within the coding sequence or were eQTLs for genes involved in neuronal development (ATE1, ENAH, and ZFHX3).

CONCLUSION

Current results improve our understanding of risk factors for SRT deterioration in cancer survivors. Higher BMI, lower physical activity, and smoking are associated with SHD. Larger samples would allow for expansion of the current findings on the genetic architecture of SRT.

Improving the computation efficiency of polygenic risk score modeling: faster in Julia

To enable computationally efficient polygenic risk score (PRS) calculations, PRS.jl translates a field standard PRS construction method, PRS-CS, to the Julia programming language.

To enable large-scale application of polygenic risk scores (PRSs) in a computationally efficient manner, we translate a widely used PRS construction method, PRS–continuous shrinkage, to the Julia programming language, PRS.jl. On nine different traits with varying genetic architectures, we demonstrate that PRS.jl maintains accuracy of prediction while decreasing the average runtime by 5.5×. Additional programmatic modifications improve usability and robustness. This freely available software substantially improves work flow and democratizes usage of PRSs by lowering the computational burden of the PRS–continuous shrinkage method.

Abstract P025: Cite-seq And Predixcan Analyses Identify Galectin-1 As A Potential Novel Mediator Of Heart Failure With Preserved Ejection Fraction In Mice And Humans

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome where patients, despite having a normal left ventricular systolic function, present with symptoms of volume overload. Recent data have shown that HFpEF is associated with elevation of inflammatory biomarkers. In a well-known rodent hypertensive model (DOCA-salt), we isolated CD45+ leukocytes from the heart and then performed CITE-Seq, a novel technique to obtain transcriptomic and surface marker expression on single cells, on a total of 4,359 and 7,600 cells from four sham and four DOCA-salt left ventricles, respectively. Analysis showed significant differential gene expression in the myeloid (macrophage/monocytic) population. We then took the top 20 genes that were differentially expressed between DOCA-salt vs sham treated myeloid cells and performed a genetic analysis called PrediXcan in Vanderbilt’s DNA databank, BioVU. Our analysis used gene expression prediction models built from the GTEx Project and tested its association with the HFpEF phenotype, which was derived on ICD-9 and 10 codes and natural language programming. From BioVU, 88,660 subjects were included in the association analysis. Of the 20 genes, 8 did not meet prediction model criteria for PrediXcan. In the remaining 12 genes, genetically predicted expression of only 2 ( Lgals1 and Ctsl ) are associated with a HFpEF phenotype. Of these, the gene encoding galectin 1, Lgals1 , had the lowest p-value (0.02) and highest beta coefficient (0.32) corresponding to an odds ratio for HFpEF of 1.38. Galectin-1 is a well known mediator of inflammation resolution in infection and tumor biology, however its role in heart failure is unknown. We are currently exploring the role of galectin-1 in the pathophysiology of HFpEF through Lgals1 -/- and LysM-Cre x Lgals1 fl/fl mice. In conclusion, using two different approaches in mice and humans, we identified galectin-1 as a new potential mediator in HFpEF development.

Abstract P050: Loss-of-function Cyp4a11 Variants Are Associated With Apparent Treatment Resistant Hypertension Identified In Electronic Medical Records; In The VA Million Veteran’s Program And Vanderbilt’s BioVU

Excessive dietary salt intake is common in patients with and salt-sensitivity contributes to the pathophysiology of resistant hypertension. Dietary salt intake regulates the excretion of 20-HETE and patients with salt-sensitive hypertension have a disrupted relationship between 20-HETE and sodium excretion. We hypothesized that rs1126742, a loss-of-function variant in the gene CYP4A11 encoding the enzyme responsible for the formation of 20-HETE, as well as a more common variant rs3890011, in partial linkage disequilibrium with rs1126742, would be associated with apparent-treatment resistant hypertension (ATRH). To test this hypothesis, we used the Department of Veteran Affairs Million Veterans Program dataset derived from electronic medical records. Patients with ATRH (cases, n=16,833), defined as uncontrolled BP of at least 140/90 mmHg despite the concurrent use of three antihypertensive medications including a thiazide diuretic or patients on four or more antihypertensive medications including a thiazide diuretic, and patients with controlled BP (controls, n=53,931) less than 135/90 mmHg on one or two antihypertensive medications were identified from the dataset using electronic algorithms. Within this population we found that there was a significant association between both rs1126742 and rs3890011 and ATRH (β=0.04, p=0.02; β=0.05, p<0.001, respectively). When we stratified the population by race, rs3890011 was significantly associated with ATRH in both whites and blacks (β=0.04, p<0.001 and β=0.06, p=0.02, respectively) while rs1126742 was associated with ATRH in blacks (β=0.07, p=0.01) but not whites. To validate these findings, we sought replication in an independent site, the Vanderbilt University Medical Center’s BioVU, a DNA databank linked with electronic medical records. We identified white patients with ATRH (n=2,998) and controlled hypertension (n=934), defined as patients with BP controlled to less than 140/90 mmHg by a single antihypertensive medication. The previous associations in whites were replicated; rs3890011 (β=0.43, p=0.02) was significantly associated with resistant hypertension while rs1126742 was not. Our findings support an association between these CYP4A11 loss-of-function variants and ATRH.

Using Mendelian randomisation to identify opportunities for type 2 diabetes prevention by repurposing medications used for lipid management

BACKGROUND

Maintaining a healthy lifestyle to reduce type 2 diabetes (T2D) risk is challenging and additional strategies for T2D prevention are needed. We evaluated several lipid control medications as potential therapeutic options for T2D prevention using tissue-specific predicted gene expression summary statistics in a two-sample Mendelian randomisation (MR) design.

METHODS

Large-scale European genome-wide summary statistics for lipids and T2D were leveraged in our multi-stage analysis to estimate changes in either lipid levels or T2D risk driven by tissue-specific predicted gene expression. We incorporated tissue-specific predicted gene expression summary statistics to proxy therapeutic effects of three lipid control medications [i.e., statins, icosapent ethyl (IPE), and proprotein convertase subtilisin/kexin type-9 inhibitors (PCSK-9i)] on T2D susceptibility using two-sample Mendelian randomisation (MR).

FINDINGS

IPE, as proxied via increased FADS1 expression, was predicted to lower triglycerides and was associated with a 53% reduced risk of T2D. Statins and PCSK-9i, as proxied by reduced HMGCR and PCSK9 expression, respectively, were predicted to lower LDL-C levels but were not associated with T2D susceptibility.

INTERPRETATION

Triglyceride lowering via IPE may reduce the risk of developing T2D in populations of European ancestry. However, experimental validation using animal models is needed to substantiate our results and to motivate randomized control trials (RCTs) for IPE as putative treatment for T2D prevention.

FUNDING

Only summary statistics were used in this analysis. Funding information is detailed under Acknowledgments.

Pharmacogenomics of cisplatin-induced neurotoxicities: Hearing loss, tinnitus, and peripheral sensory neuropathy

PURPOSE

Cisplatin is a critical component of first-line chemotherapy for several cancers, but causes peripheral sensory neuropathy, hearing loss, and tinnitus. We aimed to identify comorbidities for cisplatin-induced neurotoxicities among large numbers of similarly treated patients without the confounding effect of cranial radiotherapy.

METHODS

Utilizing linear and logistic regression analyses on 1680 well-characterized cisplatin-treated testicular cancer survivors, we analyzed associations of hearing loss, tinnitus, and peripheral neuropathy with nongenetic comorbidities. Genome-wide association studies and gene-based analyses were performed on each phenotype.

RESULTS

Hearing loss, tinnitus, and peripheral neuropathy, accounting for age and cisplatin dose, were interdependent. Survivors with these neurotoxicities experienced more hypertension and poorer self-reported health. In addition, hearing loss was positively associated with BMIs at clinical evaluation and nonwork-related noise exposure (>5 h/week). Tinnitus was positively associated with tobacco use, hypercholesterolemia, and noise exposure. We observed positive associations between peripheral neuropathy and persistent vertigo, tobacco use, and excess alcohol consumption. Hearing loss and TXNRD1, which plays a key role in redox regulation, showed borderline significance (p = 4.2 × 10^-6 ) in gene-based analysis. rs62283056 in WFS1 previously found to be significantly associated with hearing loss (n = 511), was marginally significant in an independent replication cohort (p = 0.06; n = 606). Gene-based analyses identified significant associations between tinnitus and WNT8A (p = 2.5 × 10^-6 ), encoding a signaling protein important in germ cell tumors.

CONCLUSIONS

Genetics variants in TXNRD1 and WNT8A are notable risk factors for hearing loss and tinnitus, respectively. Future studies should investigate these genes and if replicated, identify their potential impact on preventive strategies.

Genetic Examination of Hematological Parameters in SARS-CoV-2 Infection and COVID-19

Background

People hospitalized with COVID-19 often exhibit hematological alterations, such as lower lymphocyte and platelet counts, which have been reported to associate with disease prognosis. It is unclear whether inter-individual variability in baseline hematological parameters prior to acute infection influences risk of SARS-CoV-2 infection and progression to severe COVID-19.

Methods

We assessed the association of blood cell counts and indices with incident SARS-CoV-2 infection and severe COVID-19 in UK Biobank and the Vanderbilt University Medical Center Synthetic Derivative (VUMC SD). Since genetically determined blood cell measures better represent cell abundance across the lifecourse, we used summary statistics from genome-wide association studies to assess the shared genetic architecture of baseline blood cell counts and indices on COVID-19 outcomes.

Results

We observed inconsistent associations between measured blood cell indices and both SARS-CoV-2 infection and COVID-19 hospitalization in UK Biobank and VUMC SD. In Mendelian randomization analyses using genetic summary statistics, no putative causal relationships were identified between COVID-19 related outcomes and hematological indices after adjusting for multiple testing. We observed overlapping genetic association signals between hematological parameters and COVID-19 traits. For example, we observed overlap between infection susceptibility-associated variants at PPP1R15A and red blood cell parameters, and between disease severity-associated variants at TYK2 and lymphocyte and platelet phenotypes.

Conclusions

We did not find convincing evidence of a relationship between baseline hematological parameters and susceptibility to SARS-CoV-2 infection or COVID-19 severity, though this relationship should be re-examined as larger and better-powered genetic analyses of SARS-CoV-2 infection and severe COVID-19 become available.

Exploration of an alternative to body mass index to characterize the relationship between height and weight for prediction of metabolic phenotypes and cardiovascular outcomes

OBJECTIVE

Body mass index (BMI) is the most commonly used predictor of weight-related comorbidities and outcomes. However, the presumed relationship between height and weight intrinsic to BMI may introduce bias with respect to prediction of clinical outcomes. A series of analyses comparing the performance of models representing weight and height as separate interacting variables to models using BMI were performed using Vanderbilt University Medical Center's deidentified electronic health records and landmark methodology.

METHODS

Use of BMI or height-weight interaction in prediction models for established weight-related cardiometabolic traits and metabolic syndrome was evaluated. Specifically, prediction models for hypertension, diabetes mellitus, low high-density lipoprotein, and elevated triglycerides, atrial fibrillation, coronary artery disease, heart failure, and peripheral artery disease were developed. Model performance was evaluated using likelihood ratio, R 2, and Somers' Dxy rank correlation. Differences in model predictions were visualized using heat maps.

RESULTS

Compared to BMI, the maximally flexible height-weight interaction model demonstrated improved prediction, higher likelihood ratio, R 2, and Somers' Dxy rank correlation, for event-free probability for all outcomes. The degree of improvement to the prediction model differed based on the outcome and across the height and weight range.

CONCLUSIONS

Because alternative measures of body composition such as waist-to-hip ratio are not routinely collected in the clinic clinical risk models quantifying risk based on height and weight measurements alone are essential to improve practice. Compared to BMI, modeling height and weight as independent, interacting variables results in less bias and improved predictive accuracy for all tested traits. Considering an individual's height and weight opposed to BMI is a better method for quantifying individual disease risk.

Systems Approach to Integrating Preclinical Apolipoprotein E-Knockout Investigations Reveals Novel Etiologic Pathways and Master Atherosclerosis Network in Humans

OBJECTIVE

Animal models of atherosclerosis are used extensively to interrogate molecular mechanisms in serial fashion. We tested whether a novel systems biology approach to integration of preclinical data identifies novel pathways and regulators in human disease. Approach and Results: Of 716 articles published in ATVB from 1995 to 2019 using the apolipoprotein E knockout mouse to study atherosclerosis, data were extracted from 360 unique studies in which a gene was experimentally perturbed to impact plaque size or composition and analyzed using Ingenuity Pathway Analysis software. TREM1 (triggering receptor expressed on myeloid cells) signaling and LXR/RXR (liver X receptor/retinoid X receptor) activation were identified as the top atherosclerosis-associated pathways in mice (both P<1.93×10-4, TREM1 implicated early and LXR/RXR in late atherogenesis). The top upstream regulatory network in mice (sc-58125, a COX2 inhibitor) linked 64.0% of the genes into a single network. The pathways and networks identified in mice were interrogated by testing for associations between the genetically predicted gene expression of each mouse pathway-identified human homolog with clinical atherosclerosis in a cohort of 88 660 human subjects. Homologous human pathways and networks were significantly enriched for gene-atherosclerosis associations (empirical P<0.01 for TREM1 and LXR/RXR pathways and COX2 network). This included 12(60.0%) TREM1 pathway genes, 15(53.6%) LXR/RXR pathway genes, and 67(49.3%) COX2 network genes. Mouse analyses predicted, and human study validated, the strong association of COX2 expression (PTGS2) with increased likelihood of atherosclerosis (odds ratio, 1.68 per SD of genetically predicted gene expression; P=1.07×10-6).

CONCLUSIONS

PRESCIANT (Preclinical Science Integration and Translation) leverages published preclinical investigations to identify high-confidence pathways, networks, and regulators of human disease.

Abstract P256: Genetic Determinants Of Blood Pressure Associate With Apparent Treatment Resistant Hypertension

Hypertension is estimated to affect more than 49.6% of US adults 20 years and older. Of those individuals with hypertension, more than ten million are classified as apparent treatment resistant hypertensive (aTRH). The attributable risk of uncontrolled hypertension was estimated to be 49% for cardiovascular disease and 62% for stroke. We developed a polygenic risk score (PRS) for systolic (SBP) and diastolic (DBP) blood pressure to examine the association between the genetic determinants of blood pressure and aTRH with the goal of identifying high risk individuals. The meta-analyzed transethnic results of Giri et al., Biobank Japan, and Liang et al. were used to generate a PRS with PRS-CS followed by p -value thresholding, and validation in the UK Biobank (n max =341,930). Associations were modeled with logistic regression adjusted for age, age-squared, BMI, sex, and ten principal components of ancestry in BioVU’s transethnic population (n max =37,978), as well as non-Hispanic Black (n max =5,026) and non-Hispanic White (n max =28,545) subsets. The SBP PRS was significantly associated with an increased aTRH risk in the non-Hispanic White subset (1.08 (1.04 - 1.12), p = 0.00037) and transethnic (1.08 (1.04 - 1.13), p = 0.00020) populations, but not the non-Hispanic Black subset. The DBP PRS was not associated with aTRH in any population. Our findings present evidence that individuals with a higher genetic predisposition towards hypertension are at higher risk of aTRH. By integrating polygenic risk scores and clinical covariates in prediction of aTRH, individuals’ therapeutic regimens may be tailored to help maintain stable blood pressures, therefore reducing their risk of comorbidities.

Association of Apparent Treatment-Resistant Hypertension With Differential Risk of End-Stage Kidney Disease Across Racial Groups in the Million Veteran Program

[Figure: see text].

Relationship Between Blood Pressure and Incident Cardiovascular Disease: Linear and Nonlinear Mendelian Randomization Analyses

Supplemental Digital Content is available in the text.

Observational studies exploring whether there is a nonlinear effect of blood pressure on cardiovascular disease (CVD) risk are hindered by confounding. This limitation can be overcome by leveraging randomly allocated genetic variants in nonlinear Mendelian randomization analyses. Based on their association with blood pressure traits in a genome-wide association study of 299 024 European ancestry individuals, we selected 253 genetic variants to proxy the effect of modifying systolic and diastolic blood pressure. Considering the outcomes of incident coronary artery disease, stroke and the combined outcome of CVD, linear and nonlinear Mendelian randomization analyses were performed on 255 714 European ancestry participants without a history of CVD or antihypertensive medication use. There was no evidence favoring nonlinear relationships of genetically proxied systolic and diastolic blood pressure with the cardiovascular outcomes over linear relationships. For every 10-mm Hg increase in genetically proxied systolic blood pressure, risk of incident CVD increased by 49% (hazard ratio, 1.49 [95% CI, 1.38–1.61]), with similar estimates obtained for coronary artery disease (hazard ratio, 1.50 [95% CI, 1.38–1.63]) and stroke (hazard ratio, 1.44 [95% CI, 1.22–1.70]). Genetically proxied blood pressure had a similar relationship with CVD in men and women. These findings provide evidence to support that even for individuals who do not have elevated blood pressure, public health interventions achieving persistent blood pressure reduction will be of considerable benefit in the primary prevention of CVD.

Host genetic effects in pneumonia

Given the coronavirus disease 2019 (COVID-19) pandemic, investigations into host susceptibility to infectious diseases and downstream sequelae have never been more relevant. Pneumonia is a lung disease that can cause respiratory failure and hypoxia and is a common complication of infectious diseases, including COVID-19. Few genome-wide association studies (GWASs) of host susceptibility and severity of pneumonia have been conducted. We performed GWASs of pneumonia susceptibility and severity in the Vanderbilt University biobank (BioVU) with linked electronic health records (EHRs), including Illumina Expanded Multi-Ethnic Global Array (MEGAEX)-genotyped European ancestry (EA, n= 69,819) and African ancestry (AA, n = 15,603) individuals. Two regions of large effect were identified: the CFTR locus in EA (rs113827944; OR = 1.84, p value = 1.2 × 10-36) and HBB in AA (rs334 [p.Glu7Val]; OR = 1.63, p value = 3.5 × 10-13). Mutations in these genes cause cystic fibrosis (CF) and sickle cell disease (SCD), respectively. After removing individuals diagnosed with CF and SCD, we assessed heterozygosity effects at our lead variants. Further GWASs after removing individuals with CF uncovered an additional association in R3HCC1L (rs10786398; OR = 1.22, p value = 3.5 × 10-8), which was replicated in two independent datasets: UK Biobank (n = 459,741) and 7,985 non-overlapping BioVU subjects, who are genotyped on arrays other than MEGAEX. This variant was also validated in GWASs of COVID-19 hospitalization and lung function. Our results highlight the importance of the host genome in infectious disease susceptibility and severity and offer crucial insight into genetic effects that could potentially influence severity of COVID-19 sequelae.

Association of a glucagon-like peptide-1 receptor gene variant with glucose response to a mixed meal

Dipeptidyl peptidase-4 (DPP-4) inhibitors increase endogenous glucagon-like peptide-1 (GLP-1). We hypothesized that genetic variation in the gene encoding the GLP-1 receptor (GLP1R) could affect the metabolic response to DPP-4 inhibition. To evaluate the relationship between the GLP1R rs6923761 variant (G-to-A nucleic acid substitution) and metabolic responses, we performed mixed meal studies in individuals with type 2 diabetes mellitus and hypertension after 7-day treatment with placebo and the DPP-4 inhibitor sitagliptin. This analysis is a substudy of NCT02130687. The genotype frequency was 13:12:7 GG:GA:AA among individuals of European ancestry. Postprandial glucose excursion was significantly decreased in individuals carrying the rs6923761 variant (GA or AA) as compared with GG individuals during both placebo (P = 0.001) and sitagliptin treatment (P = 0.045), while intact GLP-1 levels were similar among the genotype groups. In contrast, sitagliptin lowered postprandial glucose to a greater degree in GG as compared with GA/AA individuals (P = 0.035). The relationship between GLP1R rs6923761 genotype and therapies that modulate GLP-1 signalling merits study in large populations.

Increased Incidence of Resistant Hypertension in Patients With Systemic Lupus Erythematosus: A Retrospective Cohort Study

OBJECTIVE

To compare the risk of resistant hypertension (RHTN) in patients with systemic lupus erythematosus (SLE) and in controls without SLE, and to define factors associated with RHTN in patients with SLE.

METHODS

We studied 1,044 patients with SLE and 5,241 control subjects using de-identified electronic health records from a tertiary care center. SLE was defined as ≥4 International Classification of Diseases, Ninth Revision codes for SLE and antinuclear antibody titer ≥1:160. RHTN was defined as uncontrolled blood pressure on 3 antihypertensive medications or requiring 4 or more antihypertensives to attain control. First, we compared the risk of RHTN between groups. Second, we examined the association between RHTN and all-cause mortality in patients with SLE.

RESULTS

RHTN was nearly twice as prevalent in patients with SLE compared to control subjects (10.2% and 5.3%, respectively), with an incidence rate of 10.2 versus 6.1 cases per 1,000 person-years of observation (hazard ratio [HR] 1.72 [95% confidence interval 1.28-2.30]; P < 0.001, adjusted for age, sex, race, baseline end-stage renal disease [ESRD], creatinine, and calendar year). In patients with SLE, we found associations between RHTN and black race, lower renal function, hypercholesterolemia, and increased inflammatory markers. RHTN was associated with a significantly higher mortality risk (HR 2.91, P = 0.0005) after adjustment for age, sex, race, calendar year, creatinine, baseline ESRD, and number of visits.

CONCLUSION

Patients with SLE have a higher risk of RHTN compared to frequency-matched controls, independent of multiple covariates. RHTN is an important comorbidity for clinicians to recognize in SLE, because it is associated with a higher risk of mortality.

The polygenic architecture of left ventricular mass mirrors the clinical epidemiology

Left ventricular (LV) mass is a prognostic biomarker for incident heart disease and all-cause mortality. Large-scale genome-wide association studies have identified few SNPs associated with LV mass. We hypothesized that a polygenic discovery approach using LV mass measurements made in a clinical population would identify risk factors and diseases associated with adverse LV remodeling. We developed a polygenic single nucleotide polymorphism-based predictor of LV mass in 7,601 individuals with LV mass measurements made during routine clinical care. We tested for associations between this predictor and 894 clinical diagnoses measured in 58,838 unrelated genotyped individuals. There were 29 clinical phenotypes associated with the LV mass genetic predictor at FDR q < 0.05. Genetically predicted higher LV mass was associated with modifiable cardiac risk factors, diagnoses related to organ dysfunction and conditions associated with abnormal cardiac structure including heart failure and atrial fibrillation. Secondary analyses using polygenic predictors confirmed a significant association between higher LV mass and body mass index and, in men, associations with coronary atherosclerosis and systolic blood pressure. In summary, these analyses show that LV mass-associated genetic variability associates with diagnoses of cardiac diseases and with modifiable risk factors which contribute to these diseases.

Renin-Angiotensin-Aldosterone System Modulates Blood Pressure Response During Vascular Endothelial Growth Factor Receptor Inhibition

Objectives

This study postulated that antihypertensive therapy with renin-angiotensin-aldosterone system (RAAS) inhibition may mitigate vascular endothelial growth factor inhibitor (VEGFi)–mediated increases in blood pressure more effectively than other antihypertensive medications in patients receiving VEGFi therapy.

Background

VEGFi therapy is commonly used in the treatment of cancer. One common side effect of VEGFi therapy is elevated blood pressure. Evidence suggests that the RAAS may be involved in VEGFi-mediated increases in blood pressure.

Methods

This retrospective cohort analysis was performed using a de-identified version of the electronic health record at Vanderbilt University Medical Center in Nashville, Tennessee. Subjects with cancer who were exposed to VEGFi therapy were identified, and blood pressure and medication data were extracted. Changes in mean systolic and diastolic blood pressure in response to VEGFi therapy in patients receiving RAAS inhibitor (RAASi) therapy before VEGFi initiation were compared with changes in mean systolic and diastolic blood pressure in patients not receiving RAASi therapy before VEGFi initiation.

Results

Mean systolic and diastolic blood pressure rose in both groups after VEGFi use; however, patients who had RAASi therapy before VEGFi initiation had a significantly lower increase in systolic blood pressure as compared with patients with no RAASi therapy (2.46 mm Hg [95% confidence interval: 0.7 to 4.2] compared with 4.56 mm Hg [95% confidence interval: 3.5 to 5.6], respectively; p = 0.034).

Conclusions

In a real-world clinical population, RAASi therapy before VEGFi initiation may ameliorate VEGFi-mediated increases in blood pressure. Randomized clinical trials are needed to further our understanding of the role of RAASi therapy in VEGFi-mediated increases in blood pressure.

Impaired insulin signaling in the B10.D2-Hc0 H2d H2-T18c/oSnJ mouse model of complement factor 5 deficiency

Given the chemoattractant potential of complement factor 5 (C5) and its increased expression in adipose tissue (AT) of obese mice, we determined whether this protein of the innate immune system impacts insulin action. C5 control (C5cont) and spontaneously C5-deficient (C5def, B10.D2-Hc0 H2d H2-T18c/oSnJ) mice were placed on low- and high-fat diets to investigate their inflammatory and metabolic phenotypes. Adenoviral delivery was used to evaluate the effects of exogenous C5 on systemic metabolism. C5def mice gained less weight than controls while fed a high-fat diet, accompanied by reduced AT inflammation, liver mass, and liver triglyceride content. Despite these beneficial metabolic effects, C5def mice demonstrated severe glucose intolerance and systemic insulin resistance, as well as impaired insulin signaling in liver and AT. C5def mice also exhibited decreased expression of insulin receptor (INSR) gene and protein, as well as improper processing of pro-INSR. These changes were not due to the C5 deficiency alone as other C5-deficient models did not recapitulate the INSR processing defect; rather, in addition to the mutation in the C5 gene, whole genome sequencing revealed an intronic 31-bp deletion in the Insr gene in the B10.D2-Hc0 H2d H2-T18c/oSnJ model. Irrespective of the genetic defect, adenoviral delivery of C5 improved insulin sensitivity in both C5cont and C5def mice, indicating an insulin-sensitizing function of C5.

Increased blood pressure visit-to-visit variability in patients with systemic lupus erythematosus: association with inflammation and comorbidity burden

BACKGROUND

Blood pressure visit-to-visit variability is a novel risk factor for deleterious long-term cardiac and renal outcomes in the general population. We hypothesized that patients with systemic lupus erythematosus (SLE) have greater blood pressure visit-to-visit variability than control subjects and that blood pressure visit-to-visit variability is associated with a higher comorbidity burden.

METHODS

We studied 899 patients with SLE and 4172 matched controls using de-identified electronic health records from an academic medical center. We compared blood pressure visit-to-visit variability measures in patients with SLE and control subjects and examined the association between blood pressure visit-to-visit variability and patients' characteristics.

RESULTS

Patients with SLE had higher systolic blood pressure visit-to-visit variability 9.7% (7.8-11.8%) than the control group 9.2% (7.4-11.2%), P < 0.001 by coefficient of variation. Additional measures of systolic blood pressure visit-to-visit variability (i.e. standard deviation, average real variation, successive variation and maximum measure-to-measure change) were also significantly higher in patients with SLE than in control subjects. In patients with SLE, blood pressure visit-to-visit variability correlated significantly with age, creatinine, CRP, triglyceride concentrations and the Charlson comorbidity score (all P < 0.05). Hydroxychloroquine use was associated with reduced blood pressure visit-to-visit variability (P < 0.001), whereas the use of antihypertensives, cyclophosphamide, mycophenolate mofetil and corticosteroids was associated with increased blood pressure visit-to-visit variability (P < 0.05).

CONCLUSION

Patients with SLE had higher blood pressure visit-to-visit variability than controls, and this increased blood pressure visit-to-visit variability was associated with greater Charlson comorbidity scores, several clinical characteristics and immunosuppressant medications. In particular, hydroxychloroquine prescription was associated with lower blood pressure visit-to-visit variability.

Co-Prescription of Strong CYP1A2 Inhibitors and the Risk of Tizanidine-Associated Hypotension: A Retrospective Cohort Study

Tizanidine, a widely used muscle relaxant that can lower blood pressure, is metabolized by the cytochrome P450 1A2 (CYP1A2). We studied 1,626 patients prescribed tizanidine and 5,012 prescribed cyclobenzaprine concurrently with a strong CYP1A2 inhibitor. The primary outcome was severe hypotension, defined as systolic blood pressure (SBP) ≤ 70 mmHg during periods of drug co-exposure. Severe hypotension occurred more often in the tizanidine group (2.03%; n = 33) than the cyclobenzaprine group (1.28%; n = 64); odds ratio (OR) = 1.60; P = 0.029. This difference remained statistically significant after adjustment for a log-transformed propensity score that included age, sex, race, Charlson's comorbidity index, and concurrent use of antihypertensive medications (OR = 1.57; P = 0.049). A sensitivity analysis that defined hypotension as SBP < 90 mmHg also yielded higher rates of hypotension among patients prescribed tizanidine. In conclusion, CYP1A2 inhibition increases the risk of hypotensive episodes associated with the use of tizanidine in routine clinical practice.

Abstract P289: Effect of Abaptacept on Blood Pressure in Essential Hypertensive Subjects with Rheumatological Disorders

We previously showed that abatacept, an inhibitor of T cell co-stimulation, prevents and reverses experimental hypertension. We now investigated whether it lowers blood pressure (BP) in humans. Of 1624 subjects receiving this drug in our de-identified electronic health record, 320 had hypertension and adequate baseline and follow up data (1 month to 3 years). Use of glucocorticoids (GC), non-steroidal antiinflammatory agents (NSAIDs), and antihypertensive drugs (HTND) was scored with the WHO system. ΔBPs at 1, 3 and 6 months and 1, 2 and 3 years after abatacept were adjusted for concomitant changes in medications and weights (Wt) by multivariate regression. Subjects were 80.6% female, 88.4% white, age 62±1 y, BMI 30.9±0.4 Kg/m 2 and BP 128.2±0.8/74.6±0.5 mmHg. Significant changes in confounders over time included decreases in GC, NSAID and HTND over the initial months followed by rebound beyond baseline at 2 and 3 years, and increases in Wt in these late periods. Changes in adjusted BP were limited to an increase in systolic BP at 2 years (1.75±1.04, p<0.05) and a decrease in diastolic BP at 3 years (-1.67±0.80, p<0.02). 91 subjects (28.4%) had a decrease of MAP ≥5 mmHg in at least half of the periods. ΔBP in these “responders” vs all other subjects was -10.8±0.7/-7.6±0.4, MAP -8.6±0.4 vs +5.0±0.4/+2.3±0.2, MAP +3.2±0.2, but these groups did not differ in sex, age, race, obesity, use of concomitant immunomodulators, pressors or blockers of the renin-angiotensin system (RASB). However, pooled adjusted ΔBP differed between women and men (diastolic -0.72±0.26 vs +1.48±0.48, p=0.0002; MAP -0.29±0.26 vs +1.58±0.55, p=0.003); between subjects younger and older than 65 y (systolic -0.05±0.48 vs +1.88±0.58, p=0.021; MAP -0.39±0.33 vs +0.64±0.37, p=0.037); and between those with BMI≤25 and >25 Kg/m 2 (systolic -1.31±0.79 vs +1.37±0.42, p<0.008). Finally, Δsystolic BP was -0.15±0.53 in subjects not taking and +1.42±0.50 in those taking RASB, p=0.037. In summary, long term use of abatacept mildly reduces BP in lean women with essential hypertension and rheumatological disorders. The effect is attenuated by obesity and perhaps also by aging and treatment with RASB. Further studies of abatacept in resistant essential hypertension are warranted, particularly in women.

Abstract 080: Characterization of Blood Pressure Response to Spironolactone in Patients With Resistant Hypertension using Electronic Medical Records

Spironolactone is a recommended add-on therapy for BP control in patients with resistant hypertension (RH). We hypothesized that we could use electronic medical records (EMR) to assess the BP response to the addition of spironolactone in patients with apparent RH who were on a stable anti-hypertensive regimen of at least three antihypertensive medications including a thiazide or dihydropyridine CCB.

Patients with RH were identified using a previously published algorithm. We developed an algorithm to identify patients initiated on spironolactone during a period of otherwise stable medication use from up to six months before and after the start of spironolactone to evaluate BP response.

We identified 977 RH patients (751 white and 226 black) prescribed spironolactone during a stable medication window. The median dose of spironolactone prescribed was 25 mg and 724 patients were prescribed 25 mg (74.1%). The mean decrease in SBP following spironolactone was 8.5 + 18.1 mmHg and the mean decrease in DBP was 4.0 + 9.9 mmHg, consistent with data from clinical trials.

Using a mean decrease in SBP of 5 mmHg or in DBP of 2 mmHg to define “responders,” we found that 29% (283 of 977) of patients were nonresponders. Responders had significantly higher baseline BPs (p<0.001), were older (p=0.04), and had larger decreases in the eGFR (p<0.001) and serum Na + (p<0.004) and larger increases in creatinine (p<0.001) and K + (p<0.001) after starting spironolactone than nonresponders. In blacks, glucose increased following spironolactone in responders compared to non-responders (2.27 + 40.77 vs -15.47 + 62.94 mg/dL, p=0.03); this relationship was not observed in whites.

When response was evaluated as a continuous variable, the decrease in SBP and DBP correlated with the decrease in serum Na + (p=0.04) and with the increases in serum K + (p=0.01) and creatinine (p<0.001). In blacks, there was a significant correlation between decrease in SBP and increase in glucose (p=0.04).

We have developed an algorithm to assess the BP response to spironolactone in patients with RH using the EMR. Electrolyte changes associated with the BP response to spironolactone are consistent with its mechanism of action to block the mineralocorticoid receptor and decrease activity of the epithelial Na + channel.

The Cytochrome P450 Slow Metabolizers CYP2C9*2 and CYP2C9*3 Directly Regulate Tumorigenesis via Reduced Epoxyeicosatrienoic Acid Production

Increased expression of cytochrome P450 CYP2C9, together with elevated levels of its products epoxyeicosatrienoic acids (EET), is associated with aggressiveness in cancer. Cytochrome P450 variants CYP2C9*2 and CYP2C9*3 encode proteins with reduced enzymatic activity, and individuals carrying these variants metabolize drugs more slowly than individuals with wild-type CYP2C9*1, potentially affecting their response to drugs and altering their risk of disease. Although genetic differences in CYP2C9-dependent oxidation of arachidonic acid (AA) have been reported, the roles of CYP2C9*2 and CYP2C9*3 in EET biosynthesis and their relevance to disease are unknown. Here, we report that CYP2C9*2 and CYP2C9*3 metabolize AA less efficiently than CYP2C9*1 and that they play a role in the progression of non-small cell lung cancer (NSCLC) via impaired EET biosynthesis. When injected into mice, NSCLC cells expressing CYP2C9*2 and CYP2C9*3 produced lower levels of EETs and developed fewer, smaller, and less vascularized tumors than cells expressing CYP2C9*1. Moreover, endothelial cells expressing these two variants proliferated and migrated less than cells expressing CYP2C*1. Purified CYP2C9*2 and CYP2C9*3 exhibited attenuated catalytic efficiency in producing EETs, primarily due to impaired reduction of these two variants by NADPH-P450 reductase. Loss-of-function SNPs within CYP2C9*2 and CYP2C9*3 were associated with improved survival in female cases of NSCLC. Thus, decreased EET biosynthesis represents a novel mechanism whereby CYPC29*2 and CYP2C9*3 exert a direct protective role in NSCLC development.Significance: These findings report single nucleotide polymorphisms in the human CYP2C9 genes, CYP2C9*2 and CYP2C9*3, exert a direct protective role in tumorigenesis by impairing EET biosynthesis. Cancer Res; 78(17); 4865-77. ©2018 AACR.

Characteristics and treatment of African-American and European-American patients with resistant hypertension identified using the electronic health record in an academic health centre: a case-control study

OBJECTIVE

To identify patients with hypertension with resistant and controlled blood pressure (BP) using electronic health records (EHRs) in order to elucidate practices in the real-world clinical treatment of hypertension and to enable future genetic studies.

DESIGN

Using EHRs, we developed and validated algorithms to identify patients with resistant and controlled hypertension.

SETTING

An academic medical centre in Nashville, Tennessee.

POPULATION

European-American (EA) and African-American (AA) patients with hypertension.

MAIN OUTCOME MEASURES

Demographic characteristics: race, age, gender, body mass index, outpatient BPs and the history of diabetes mellitus, chronic kidney disease stage 3, ischaemic heart disease, transient ischaemic attack, atrial fibrillation and sleep apnoea.

MEDICATION TREATMENT

All antihypertensive medication classes prescribed to a patient at the time of classification and ever prescribed following classification.

RESULTS

The algorithms had performance metrics exceeding 92%. The prevalence of resistant hypertension in the total hypertensive population was 7.3% in EA and 10.5% in AA. At diagnosis, AA were younger, heavier, more often female and had a higher incidence of type 2 diabetes and higher BPs than EA. AA with resistant hypertension were more likely to be treated with vasodilators, dihydropyridine calcium channel blockers and alpha-2 agonists while EA were more likely to be treated with angiotensin receptor blockers, renin inhibitors and beta blockers. Mineralocorticoid receptor antagonists use was increased in patients treated with more than four antihypertensive medications compared with patients treated with three (12.4% vs 2.6% in EA, p<0.001; 12.3% vs 2.8% in AA, p<0.001). The number of patients treated with a mineralocorticoid receptor antagonist increased to 37.4% in EA and 41.2% in AA over a mean follow-up period of 7.4 and 8.7 years, respectively.

CONCLUSIONS

Clinical treatment of resistant hypertension differs in EA and AA patients. These results demonstrate the feasibility of identifying resistant hypertension using an EHR.

Abstract P147: Differences in the Treatment of Resistant Hypertension in African Americans and European Americans in a Clinical Setting

Using Vanderbilt University Medical Center’s electronic health record (EHR), we tested the hypothesis that we could identify patients with resistant hypertension (RH) and patterns of treatment of RH in a real-world clinical setting.

Patients were identified as having RH if they had blood pressure (BP) >140/90 mmHg despite concurrent treatment with three different classes of antihypertensive medications including a thiazide diuretic or amlodipine or similar dihydropyridine (DHP) calcium channel blocker (CCB) or if they were treated with four antihypertensive medications including the same classes. Secondary causes and chronic kidney disease were excluded. Among 186,015 European American (EA) and 33,576 African American (AA) hypertensive patients, 13,541 (7.3%) and 3,541 (10.5%) had RH, respectively. AA with RH were younger, heavier, more often female, had a higher incidence of type 2 diabetes, and had higher systolic and diastolic BPs than EA with RH. AA with RH were more likely than EA to be treated with vasodilators, DHP CCB, and α2-agonists. EA were more likely to be treated with angiotensin receptor blockers, renin inhibitors, and beta-blockers. Mineralocorticoid receptor (MR) antagonists were used in both EA and AA patients and use was increased in patients treated with > four antihypertensive medications compared to patients treated with three (2.6% vs 12.4% in EA, p<0.001; 2.8% vs 12.3% in AA, p<0.001). The number of patients treated with an MR antagonist increased to 36.6% in EA and 40.3% in AA over a mean follow-up period of 7.4 and 8.7 years, respectively.

Our results demonstrate that clinicians use different classes of medication to treat RH in AA and EA.

Hypertension and Type 2 Diabetes Are Associated With Decreased Inhibition of Dipeptidyl Peptidase-4 by Sitagliptin

Context

Patients with diabetes often have comorbidities such as hypertension. It is not known how individual characteristics influence response to dipeptidyl peptidase-4 (DPP4) inhibitors.

Objective

We tested the hypothesis that individual characteristics, sitagliptin dose, and genetic variability in DPP4 influence DPP4 activity during sitagliptin.

Design and Setting

Post hoc analysis of clinical and laboratory data from individuals randomized to sitagliptin versus placebo in crossover studies.

Patients and Interventions

Sixty-five subjects [27 with type 2 diabetes mellitus (T2DM) and hypertension, 38 healthy controls] were randomized to 100 mg/d sitagliptin or 200 mg sitagliptin and matching placebo in double-blind, crossover fashion. Fasting blood was obtained at baseline and 60 to 180 minutes after sitagliptin or placebo.

Main Outcome Measures

DPP4 activity and antigen during placebo and sitagliptin and DPP4 inhibition during sitagliptin.

Results

Sitagliptin 100 mg/d was less effective at inhibiting DPP4 activity in individuals with T2DM and hypertension than in healthy controls (P = 0.001, percent inhibition). In healthy controls, 100 mg/d sitagliptin was not as effective as single-dose 200 mg sitagliptin (P = 0.001, percent inhibition). DPP4 genotypes rs2909451 TT (P = 0.02) and rs759717 CC (P = 0.02) were associated with DPP4 activity during sitagliptin. In multivariable analyses, T2DM with hypertension, sitagliptin dose, age, systolic blood pressure, DPP4 activity during placebo, and rs2909451 genotype were significantly associated with DPP4 activity during sitagliptin.

Conclusions

Sitagliptin is less effective in inhibiting DPP4 in individuals with T2DM and hypertension than in healthy controls. Higher doses of DPP4 inhibitors may be required in patients with the metabolic syndrome.

Association of gain-of-function EPHX2 polymorphism Lys55Arg with acute kidney injury following cardiac surgery

Twenty to thirty percent of patients undergoing cardiac surgery develop acute kidney injury (AKI). In mice, inhibition of soluble epoxide hydrolase (sEH) attenuates renal injury following ischemia-reperfusion. We tested the hypothesis that functional variants of EPHX2, encoding sEH, are associated with AKI after cardiac surgery. We genotyped patients in two independent cardiac surgery cohorts for functional EPHX2 polymorphisms, Lys55Arg and Arg287Gln, and determined AKI using Acute Kidney Injury Network criteria. The 287Gln variant was not associated with AKI. In the discovery cohort, the gain-of-function 55Arg variant was associated with an increased incidence of AKI in univariate (p = 0.03) and multivariable (p = 0.04) analyses. In white patients without chronic kidney disease (CKD), the 55Arg variant was independently associated with AKI with an OR of 2.04 (95% CI 0.95–4.42) for 55Arg heterozygotes and 31.53 (1.57–633.19) for homozygotes (p = 0.02), after controlling for age, sex, body mass index, baseline estimated glomerular filtration rate, and use of cardiopulmonary bypass. These findings were replicated in the second cardiac surgery cohort. 12,13- and total- dihydroxyoctadecanoic acids (DiHOME): epoxyoctadecanoic acids (EpOME) ratios were increased in EPHX2 55Arg variant carriers, consistent with increased hydrolase activity. The EPHX2 Lys55Arg polymorphism is associated with AKI following cardiac surgery in patients without preexisting CKD. Pharmacological strategies to decrease sEH activity might decrease postoperative AKI.

VNTR diversity in Yersinia pestis isolates from an animal challenge study reveals the potential for in vitro mutations during laboratory cultivation

Underlying mutation rates and other evolutionary forces shape the population structure of bacteria in nature. Although easily overlooked, similar forces are at work in the laboratory and may influence observed mutations. Here, we investigated tissue samples and Yersinia pestis isolates from a rodent laboratory challenge with strain CO92 using whole genome sequencing and multi-locus variable-number tandem repeat (VNTR) analysis (MLVA). We identified six VNTR mutations that were found to have occurred in vitro during laboratory cultivation rather than in vivo during the rodent challenge. In contrast, no single nucleotide polymorphism (SNP) mutations were observed, either in vivo or in vitro. These results were consistent with previously published mutation rates and the calculated number of Y. pestis generations that occurred during the in vitro versus the in vivo portions of the experiment. When genotyping disease outbreaks, the potential for in vitro mutations should be considered, particularly when highly variable genetic markers such as VNTRs are used.

Genetic variation at the MHC DRB1 locus is similar across Gunnison's prairie dog (Cynomys gunnisoni) colonies regardless of plague history

Yersinia pestis was introduced to North America around 1900 and leads to nearly 100% mortality in prairie dog (Cynomys spp.) colonies during epizootic events, which suggests this pathogen may exert a strong selective force. We characterized genetic diversity at an MHC class II locus (DRB1) in Gunnison's prairie dog (C. gunnisoni) and quantified population genetic structure at the DRB1 versus 12 microsatellite loci in three large Arizona colonies. Two colonies, Seligman (SE) and Espee Ranch (ES), have experienced multiple plague‐related die‐offs in recent years, whereas plague has never been documented at Aubrey Valley (AV). We found fairly low allelic diversity at the DRB1 locus, with one allele (DRB1*01) at high frequency (0.67–0.87) in all colonies. Two other DRB1 alleles appear to be trans‐species polymorphisms shared with the black‐tailed prairie dog (C. ludovicianus), indicating that these alleles have been maintained across evolutionary time frames. Estimates of genetic differentiation were generally lower at the MHC locus (F_ST = 0.033) than at microsatellite markers (F_ST = 0.098). The reduced differentiation at DRB1 may indicate that selection has been important for shaping variation at MHC loci, regardless of the presence or absence of plague in recent decades. However, genetic drift has probably also influenced the DRB1 locus because its level of differentiation was not different from that of microsatellites in an F_ST outlier analysis. We then compared specific MHC alleles to plague survivorship in 60 C. gunnisoni that had been experimentally infected with Y. pestis. We found that survival was greater in individuals that carried at least one copy of the most common allele (DRB1*01) compared to those that did not (60% vs. 20%). Although the sample sizes of these two groups were unbalanced, this result suggests the possibility that this MHC class II locus, or a nearby linked gene, could play a role in plague survival.

Abstract 094: Gain-of-function EPHX2 Variant rs41507953 Is Associated With Acute Kidney Injury Following Cardiac Surgery

Acute kidney injury (AKI) affects 20-30% of patients following cardiac surgery and predicts increased mortality. Murine models suggest that epoxyeicosatrienoic acids (EETs) protect against renal ischemia/reperfusion injury, a contributor to AKI following cardiac surgery. Soluble epoxide hydrolase (sEH), encoded by EPHX2, hydrolyzes EETs to less active DHETs. We tested the hypothesis that a gain-of-function EPHX2 variant, rs41507953, is associated with AKI following cardiac surgery.

We first studied 371 cardiac surgery patients (67.3% male, mean age 65.6±12.9years and BMI 28.5±6.17kg/m 2 ) enrolled in a clinical trial in which DNA was collected. Ninety-eight patients (26.4%) developed AKI, defined by AKIN criteria. Rs41507953 genotypes were in Hardy-Weinberg equilibrium (AA:AG:GG=297:68:6). There was a significant association between the gain-of-function “G” allele and AKI, p=0.006. Adjusting for known risk factors for AKI including estimated glomerular filtration rate (eGFR), age, sex, race, history of diabetes, BMI, and use of cardiopulmonary bypass the rs41507953 “G” allele remained independently associated with higher rates of AKI [OR=2.09 (95%CI 1.132-3.848, p=0.018). We replicated this association between the rs41507953 “G” allele and AKI in another cohort of 800 cardiac surgery patients.

To assess the association between the rs41507953 “G” allele and sEH activity we measured 9,10 or 12,13-dihydroxyoctadecanoic acid/9,10 or 12,13-epoxyoctadecanoic acid (DiHOME/EpOME) ratios, measures of sEH activity, in plasma collected from 26 AA and 5 AG individuals in the original cohort. sEH activity was highest in plasma collected post-protamine administration. The 12,13 DiHOME/EpOME and the total DiHOME/EpOME ratios post-protamine were significantly greater in the AG vs. the AA genotype group, 11.66±12.91 vs. 2.32±3.03 (p=0.002) and 28.35±47.79 vs. 4.03±7.96 (p=0.014), respectively.

An EPHX2 variant with increased sEH activity is associated with AKI following cardiac surgery. Pharmacologic inhibition of the sEH enzyme might protect patients from AKI following cardiac surgery.

Abstract 270: Successful Development and Implementation of an Algorithm to Identify Resistant Hypertension in the Electronic Medical Record

Resistant hypertension (RH) affects 8.4 to 17.4% of the hypertensive population, and is associated with an elevated risk of end-organ damage. To identify genetic or environmental factors associated with RH, we developed an algorithm to phenotype patients using electronic medical records (EMRs).

We modified a previously validated algorithm for detecting patients with RH from 158,128 adults in BioVU, a DNA databank incorporating clinical data from EMRs. We defined patients as having RH if they had a SBP>140 mmHg or a DBP>90 mmHg for at least one month while receiving at least three anti-hypertensive agents including 25 mg HCTZ or equivalent doses of another thiazide diuretic or amlodipine 5 or 10 mg, or equivalent doses of a similar calcium channel blocker. Patients could be controlled after addition of a fourth drug. Patients were defined as having controlled hypertension if they carried a diagnosis of hypertension, were taking at least one and no more than two anti-hypertensive medications, and had a SBP<135 and a DBP<90 mmHg on repeated measurement. Drug exposures were identified from electronic-prescribing tools and MedEx.

To validate the algorithm, we conducted an independent review of 150 EMRs from patients classified as having resistant or controlled hypertension. The accuracy of the algorithm was 94.7%. Among 55,477 patients with hypertension in BioVU, 14.2% met the criteria for RH. The table shows the characteristics of patients with resistant and controlled hypertension.

This study demonstrates the successful use of a phenotyping algorithm to identify subjects with RH from EMR data and provides important characteristics of patients with RH in a real-world clinical setting.

Abstract 256: Loss-of-function Gln287 Variant in EPHX2 is Associated With Increased Insulin Sensitivity

Epoxyeicosatrienoic acids (EETs) induce vasodilation via activation of calcium-sensitive potassium channels and smooth muscle cell hyperpolarization. Soluble epoxide hydrolase (sEH) hydrolyzes EETs to less biologically active metabolites. The variant Gln287 of EPHX2 encodes for a sEH enzyme with reduced hydrolase activity. In murine models of type 2 diabetes, inhibition of sEH or EPHX2 deletion results in improved insulin sensitivity. In humans, forearm blood flow is significantly increased in Gln287 variant allele carriers. Given that insulin sensitivity is influenced by vascular perfusion, we hypothesized that insulin sensitivity would be increased in Gln287-carriers compared with wild-type individuals. Insulin secretion and sensitivity were assessed in 63 volunteers (43 with metabolic syndrome, 34 females, 42.5 ± 13 years old, 15 black Americans) during hyperglycemic clamps. Statistical analyses were adjusted for BMI. Plasma total- (r=0.63, p=0.007), 14-15- (r=0.62, p=0.008), and 11-12- (r=0.57, p=0.02) EET concentrations correlated with insulin sensitivity. There was no effect of genotype on insulin secretion (not shown). In individuals without metabolic syndrome, insulin sensitivity was significantly increased in Gln287 variant carriers compared with wild-type individuals (Fig. A). Insulin sensitivity was decreased in individuals with the metabolic syndrome, but also trended higher in Gln287 variant carriers when compared with wild-type individuals (Fig. B). Taken together, these results suggest that the loss-of-function Gln287 variant of EPHX2 is associated with increased insulin sensitivity.