Postural Changes in Blood Pressure Associated with Interactions between Candidate Genes for Chronic Respiratory Diseases and Exposure to Particulate Matter

BACKGROUND: Fine particulate matter [aerodynamic diameter <= 2.5 mu m (PM(2.5))] has been associated with autonomic dysregulation. OBJECTIVE: We hypothesized that PM(2.5) influences postural changes in systolic blood pressure (Delta SBP) and in diastolic blood pressure (Delta DBP) and that this effect is modified by genes thought to be related to chronic lung disease. METHODS: We measured blood pressure in participants every 3-5 years. Delta SBP and Delta DBP were calculated as sitting minus standing SBP and DBP. We averaged PM(2.5) over 48 hr before study visits and analyzed 202 single nucleotide polymorphisms (SNPs) in 25 genes. To address multiple comparisons, data were stratified into a split sample. In the discovery cohort, the effects of SNP x PM2.5 interactions on Delta SBP and Delta DBP were analyzed using mixed models with subject-specific random intercepts. We defined positive outcomes as p < 0.1 for the interaction; we analyzed only these SNPs in the replicate cohort and confirmed them if p < 0.025 with the same sign. Confirmed associations were analyzed within the full cohort in models adjusted for anthropometric and lifestyle factors. RESULTS: Nine hundred forty-five participants were included in our analysis. One interaction with rs9568232 in PHD finger protein 11 (PHF11) was associated with greater Delta DBP. Interactions with rs1144393 in matrix metalloprotease 1 (MMP1) and rs16930692, rs7955200, and rs10771283 in inositol 1,45-triphosphate receptor, type 2 (ITPR2) were associated with significantly greater Delta SBP. Because SNPs associated with Delta SBP in our analysis are in genes along the renin-angiotensin pathway, we then examined medications affecting that pathway and observed significant interactions for angiotensin receptor blockers but not angiotensin-converting enzyme inhibitors with PM(2.5). CONCLUSIONS: PM2.5 influences blood pressure and autonomic function. This effect is modified by genes and drugs that also act along this pathway.