medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 Pathway-specific Polygenic Risk Scores (PRS) identify OSA-related pathways
2 differentially moderating genetic susceptibility to CAD
3 Goodman: Pathway-specific effects of OSA on genetic CAD risk
4 Matthew O Goodman,1,2,3 Brian E Cade,1,2,3 Neomi Shah,4 Tianyi Huang,2,5 Hassan S Dashti,3,6,7
5 Richa Saxena,1,2,3,6,7 Martin K Rutter,8,9 Peter Libby,10 Tamar Sofer,1,2 Susan Redline1,2
6 Affiliations:
7 1Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital and Harvard
8 Medical School, Boston, MA
9 2Division of Sleep Medicine, Harvard Medical School, Boston, MA
10 3Program in Medical and Population Genetics, Broad Institute, Cambridge, MA, USA
11 4Icahn School of Medicine at Mount Sinai, New York, NY
12 5Channing Division of Network Medicine, Brigham and Women’s Hospital and Harvard Medical
13 School, Boston, MA
14 6Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
15 7Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital
16 and Harvard Medical School, Boston, MA, USA
17 8Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences,
18 Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic
19 Health Science Centre, Manchester, United Kingdom
20 9Diabetes, Endocrinology and Metabolism Centre, Manchester University NHS Foundation
21 Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
22 10Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's
23 Hospital, Harvard Medical School, Boston, MA, USA.
NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 Corresponding Author:
2 Matthew Goodman
3 Brigham and Women’s Hospital
4 221 Longwood Avenue
5 Boston, MA 02115
6 (617) 525-9767
8
9 Total word count: 8867 (including the title page, abstract, text, references, tables, and figures
10 legends) medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 ABSTRACT
2 Background—
3 Obstructive sleep apnea (OSA) and its features, such as chronic intermittent hypoxia (IH), may
4 differentially affect specific molecular pathways and processes in the pathogenesis of coronary
5 artery disease (CAD) and influence the subsequent risk and severity of CAD events. In
6 particular, competing adverse (e.g. inflammatory) and protective (e.g. increased coronary
7 collateral blood flow) mechanisms may operate, but remain poorly understood. We hypothesize
8 that common genetic variation in selected molecular pathways influences the likelihood of CAD
9 events differently in individuals with and without OSA, in a pathway-dependent manner.
10 Methods—
11 We selected a cross-sectional sample of 471,877 participants from the UK Biobank,
12 among whom we ascertained 4,974 to have OSA, 25,988 to have CAD, and 711 to have both.
13 We calculated pathway-specific polygenic risk scores (PS-PRS) for CAD, based on 6.6 million
14 common variants evaluated in the CARDIoGRAMplusC4D genome-wide association study
15 (GWAS), annotated to specific genes and pathways using functional genomics databases. Based
16 on prior evidence of involvement with IH and CAD, we tested PS-PRS for the HIF-1, VEGF,
17 NFkB and TNF signaling pathways.
18 Results—
19 In a multivariable-adjusted logistic generalized additive model, elevated PS-PRSs for the
20 KEGG VEGF pathway (39 genes) associated with protection for CAD in OSA (interaction odds
21 ratio 0.86, p = 6E-04). By contrast, the genome-wide CAD PRS did not show evidence of
22 statistical interaction with OSA.
23 Conclusions— medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1
2 We find evidence that pathway-specific genetic risk of CAD differs between individuals with
3 and without OSA in a qualitatively pathway-dependent manner, consistent with the previously
4 studied phenomena whereby features of OSA may have both positive and negative effects on
5 CAD. These results provide evidence that gene-by-environment interaction influences CAD risk
6 in certain pathways among people with OSA, an effect that is not well-captured by the genome-
7 wide PRS. These results can be followed up to study how OSA interacts with genetic risk at the
8 molecular level, and potentially to personalize OSA treatment and reduce CAD risk according to
9 individual pathway-specific genetic risk profiles.
10 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 INTRODUCTION
2 Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent episodes
3 of hypoxemia during sleep, sleep fragmentation, and activation of the sympathetic nervous
4 system, potentially stimulating pro-inflammatory and pro-thrombotic pathways that drive
5 atherosclerosis [1]. Epidemiological studies implicate OSA as a potentially modifiable risk factor
6 for cardiovascular disease (CVD), stimulating research aimed at quantifying the impact of OSA
7 and its treatment on both coronary artery disease (CAD) and cerebrovascular disease [2]. While
8 OSA increases the incidence of cerebrovascular disease, weaker and less consistent associations
9 support associations between OSA and incident CAD [3]. Moreover, large clinical trials of the
10 effect of positive airway pressure (PAP) treatment of OSA on composite CVD outcomes have
11 provided equivocal results, in some cases with point estimates in the direction of increased risk
12 in the treatment group [4-7].
13 Potential explanations for disappointing results of PAP RCTs include treatment non-
14 adherence, non-optimal trial participant selection (e.g. advanced CVD at baseline) and limited
15 statistical power [8, 9]. Another possibility is that putative CVD benefits of OSA treatment may
16 vary across individuals, influenced by factors related to characteristics of OSA-related stress not
17 captured by the traditional metric of OSA severity (apnea hypopnea index, AHI), as well as by
18 underlying host characteristics [10, 11], including genetic predisposition to CVD and genetic
19 variation within known OSA pathways [12, 13]. Moreover, some features of OSA might even
20 prove protective for CVD in some individuals, and therefore treatment of OSA with PAP could
21 increase CVD risk among those individuals [14]. This hypothesis derives support from human
22 and animal studies showing that exposure to intermittent hypoxemia - a cardinal feature of OSA
1 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 - can promote collateral blood flow, reflective of well-known effects of ischemic preconditioning
2 [15].
3 The need to develop a precision medicine-informed approach to CVD risk stratification
4 in OSA agrees with data indicating that OSA-related CVD risk varies across subgroups defined
5 by clusters of phenotypic traits [16]. A central question, and the one that we address here, is
6 whether genetic variation in CAD risk interacts with OSA features to modulate CAD risk in a
7 pathway-dependent manner. We conceptualize repeated intermittent hypoxia (IH) and
8 reoxygenation as a modifying environment for preexisting genetic risk for CAD, locating our
9 analysis within a gene-by-environment (GxE) interaction paradigm. Our pathway-level GxE
10 approach provides a new scale on which to study the genetic architecture of CAD susceptibility
11 and its modification by OSA.
12 We build on prior work that (1) identified genetic markers for CAD risk involved in
13 atherosclerosis, small vessel disease, inflammatory pathways, and angiogenesis, with evidence
14 from genome-wide association studies (GWAS), expression studies, animal experiments and
15 clinical trials [17-19]; and (2) showed the influence of IH on a variety of pathways (in positive
16 and negative directions) relevant to CAD, including redox, inflammatory and angiogenic
17 pathways [20].
18 Our approach considers effect modification of genetic risk, aggregated to the pathway
19 level, and investigates pathway-specific polygenic risk scores (PS-PRS) for CAD. PRSs have
20 demonstrated success in identifying high risk populations, but may perform poorly due to overly
21 simplistic dimension reduction when compared with non-linear methods to summarize risk
22 across many alleles [21, 22]. Here we consider a novel PRS approach, where we group markers
2 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 by pathways to create multiple PS-PRSs aligned logically with genetic architecture, to facilitate
2 investigation of GxE interaction at the pathway level.
3 We hypothesized that common genetic variation, in specific molecular pathways for
4 CAD that are linked to the pathophysiology of OSA, influences the likelihood of CAD events
5 differently in individuals with and without OSA, in a pathway-dependent manner. Our work was
6 motivated by the potential for differential effects of OSA on multiple processes that impact
7 CAD, such as inflammation and atherosclerosis, thrombosis, collateral vessel formation (via
8 angiogenesis), control of coronary artery blood flow, and plaque disruption. Of central interest is
9 the idea that OSA could be a “double-edged sword” with both positive or negative effects on
10 CAD. In particular, intermittent hypoxia – a physiological stress characteristic of OSA – may
11 exert either positive effects through ischemic preconditioning or negative effects by boosting
12 atherosclerotic processes including inflammation [14, 15]. We pre-selected four regulatory
13 pathways of interest based on our hypotheses of the impacts of chronic IH on angiogenic and
14 inflammatory processes in CAD, the HIF-1, VEGF, NFkB and TNF signaling pathways. We
15 focused on these four representative pathways for their recognized roles in these processes,
16 which have been previously shown to involve differential expression of constituent genes in
17 OSA [23-32].
18 By investigating whether OSA enhances, does not change, or ameliorates genetic risk of
19 developing CAD among individuals with specific risk allele profiles within these pathways, we
20 aim to provide new mechanistic insight into the biological effects of OSA on CAD. In addition,
21 we explore the ability to identify patients with OSA who may have either protection against or
22 increased risk of CAD events from their OSA status according to their specific genetic profile.
23 Ultimately, we propose that this approach provides a novel step on the path toward
3 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 understanding the complex role of OSA in CAD and formulating a personalized approach to
2 treatment.
3
4 METHODS
5 UK Biobank
6 The UK Biobank (UKBB) cohort consists of 502,620 participants, recruited between
7 2006 and 2010 from across the United Kingdom, and is described elsewhere in detail [33].
8 Participants were assessed at baseline using questionnaires that included components for
9 ascertaining medical conditions, lifestyle, and demographic information. Additional interviews
10 were conducted by trained medical staff to assess medical history, health status and medication
11 intake. We used available self-reported doctor-diagnosed medical conditions and ICD10 codes
12 derived from the UKBB hospital episode inpatient data set (retrieved 03/21/2019) to define
13 medical conditions of interest. Participants were genotyped on two closely related genotyping
14 arrays: UK BiLEVE: N = 49,939, and UK Biobank Axiom: 438,343. In total, 488,282
15 participants were genotyped. All genotypes were then imputed using reference sequence data as
16 previously described [34]. The National Health Service National Research Ethics Service (ref.
17 11/NW/0382) gave approval for the UK Biobank study, with each participant providing written
18 informed consent.
19 OSA status assessment
20 We defined cases and controls as follows: Cases of OSA must have had self-reported
21 snoring AND at least one of the following sleep apnea diagnoses:
4 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 1) an ICD101 code G47.3 for sleep apnea (N = 6643)
2 OR
3 2) a self-report of doctor diagnosed sleep apnea documented during an interview with a
4 trained medical professional (UKBB field 20002, coding 1123: sleep apnoea) (N = 1757).
5 Controls were non-cases. Individuals who could not be confidently defined as either
6 cases or controls were excluded. To reduce the possibility of including cases of central sleep
7 apnea ascertained using sleep apnea diagnostic codes, we required snoring (a cardinal symptom
8 of OSA), documented by self-report in the UKBB sleep questions interview. Among participants
9 without OSA we excluded those who self-reported both snoring and daytime sleepiness, two
10 common symptoms of OSA. A total of 471,877 participants (4,974 OSA cases) with complete
11 covariate data were available after making these exclusions.
12 CAD status assessment
13 Coronary artery disease (CAD) cases were assessed based on a composite definition,
14 including UKBB participants with self-reported heart attack/myocardial infarction, phecode
15 411.2 or UKBB algorithmic ascertainment for myocardial infarction, including self-report,
16 hospital admission, or death certificate.
17 Covariate Assessment
18 Diagnostic information for medical conditions were obtained from the UKBB data sets
19 for self-reported doctor-diagnosed non-cancer illness and hospital episode inpatient diagnostic
20 codes. ICD10 codes were collapsed to medically interpretable groupings using the phecode
21 system [35], using Phecode Map version 1.2 for WHO ICD10’s. Hypertension, type 1 (T1D) and
1 ICD9 records were not analyzed as A) ICD9 codes come from a unique subset of 20k Scottish participants with available hospital inpatient episodes from 1980 to 1996, whereas the ICD10 data was collected almost exclusively after 1996 B) the fact that these ICD9s contain no instances of sleep apnea codes 327.23 or 327.2, nor any sleep codes in the 327 range.
5 medRxiv preprint doi: https://doi.org/10.1101/2021.04.27.21255520; this version posted April 30, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license .
1 type 2 diabetes (T2D), COPD, asthma, and pulmonary fibrosis were ascertained as composite
2 phenotypes, as described in Supplementary Table S1. Additional covariates were self-reported
3 race, genotype platform (BiLEVE vs Axiom) and UK Biobank-provided genetic PCs.
4 Polygenic Risk Score Construction
5 We based our analysis of genetic CAD risk on a published PRS described by Khera et al
6 [36], with single nucleotide variant (SNV) effects estimated for each of 6,630,150 SNVs, using
7 the linkage disequilibrium (LD) aware PRS algorithm LDPred [37] and summary statistics from
8 the CARDIoGRAMplusC4D Consortium CAD GWAS of 60,801 cases and 123,504 controls of
9 mainly European ancestry [38].
10 Pathway specific polygenic risk scores (PS-PRSs) were calculated for each individual as
11 the effect-weighted sum of the count of risk alleles at each locus across all pathway SNVs:
12 �� − ��� = � �