Preconception Exposure to Fine Particulate Matter Leads to Cardiac Dysfunction in Adult Male Offspring

Abstract

Background Particulate matter (particles < 2.5 μm [ PM 2.5]) exposure during the in utero and postnatal developmental periods causes cardiac dysfunction during adulthood. Here, we investigated the potential priming effects of preconception exposure of PM 2.5 on cardiac function in adult offspring. Methods and Results Male and female friend leukemia virus b (FVB) mice were exposed to either filtered air ( FA ) or PM 2.5 at an average concentration of 38.58 μg/m3 for 6 hours/day, 5 days/week for 3 months. Mice were then crossbred into 2 groups: (1) FA male× FA female (both parents were exposed to FA preconception) and, (2) PM 2.5male× PM 2.5female (both parents were exposed to PM 2.5 preconception). Male offspring were divided: (1) preconception FA (offspring born to FA exposed parents) and, (2) preconception PM 2.5 (offspring born to PM 2.5 exposed parents) and analyzed at 3 months of age. Echocardiography identified increased left ventricular end systolic volume and reduced posterior wall thickness, reduced %fractional shortening and %ejection fraction in preconception PM 2.5 offspring. Cardiomyocytes isolated from preconception PM 2.5 offspring showed reduced %peak shortening, -dL/dT, TPS 90 and slower calcium reuptake (tau). Gene and protein expression revealed modifications in markers of inflammation ( IL -6, IL -15, TNF α, NF қB, CRP , CD 26E, CD 26P, intercellular adhesion molecule 1, and monocyte chemoattractant protein-1) profibrosis (collagen type III alpha 1 chain), oxidative stress ( NOS 2), antioxidants (Nrf2, SOD , catalase), Ca2+ regulatory proteins ( SERCA 2a, p- PLN , NCX ), and epigenetic regulators (Dnmt1, Dnmt3a, Dnmt3b, Sirt1, and Sirt2) in preconception PM 2.5 offspring. Conclusions Preconception exposure to PM 2.5 results in global cardiac dysfunction in adult offspring, suggesting that abnormalities during development are not limited to the prenatal or postnatal periods but can also be determined before conception.

Keywords: calcium; cardiovascular function; inflammation; myocyte; particulate matter; preconception.

Figures

Figure 1

Body weight parameters from mice born to preconception FA or PM 2.5‐exposed parents. A, Birth weight (n=42–49 pups/group), (B) body weight (n=12–13 mice/group), (C) body surface area (BSA) (n=12–13 mice/group), (D) heart weight (n=12–13 mice/group), (E) heart weight/body weight (HW/BW) (n=12–13 mice/group), (F) heart weight/tibial length (HW/TL) (n=12–13). Data are expressed as ±SEM. *P<0.05, ***P<0.001 vs preconception FA controls. A, Represents birth weight of all offspring (irrespective of sex). B through F, Represent parameters that were analyzed in 3‐month‐old male offspring only. PC FA indicates preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter).

Figure 2

Transthoracic echocardiography to assess cardiac function of 3‐month‐old mice that were born to preconception FA or PM 2.5 exposed parents. A, LVESd, (B) PWTs, (C) %FS, (D) %EF. Data were collected from 10 to 12 mice in each group. Five beat cycles were captured and 3 loops averaged per assessment. Data are expressed as ±SEM. %EF indicates %ejection fraction; %FS, %fractional shortening; LVESd, left ventricular end‐diastolic dimension; PC FA, preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter); PWTs, posterior wall thickness during systole. *P<0.05, **P<0.01 vs PC FA controls.

Figure 3

In vitro cardiomyocyte functional and calcium signaling parameters obtained from 3‐month‐old mice that were born to preconception filtered air or particulate matter (A) %peak shortening (%PS), (B) negative velocity (‐dL/dT), (C) time‐to‐peak shortening (TPS90), (D) fluorescence decay rate (τ), (E) calcium transient amplitude (Δ340/380). Data were collected from 70 to 80 cardiomyocytes isolated from 9 to 10 mice per group taken from individual litters. Data are expressed as mean±SEM. %PS indicates %peak shortening; ‐dL/dT, negative velocity; PC FA indicates preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter); TPS90, time‐to‐peak shortening. *P<0.05, **P<0.01 vs PC FA controls.

Figure 4

Western blot analysis showing expression Ca2+ handling proteins (A) SERCA‐2A, (B) p‐PLN; (C) NCX. Representative Western blot shown above and quantification below. Data were obtained from 3‐month‐old mouse hearts (n=6 mice/group) that were born to preconception filtered air or particulate matter (<2.5 μm in diameter) exposed parents and expressed as mean±SEM. NCX indicates Na+/Ca2+ exchanger; PC FA indicates preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter); p‐PLN, phosphorylated phospholamban; SERCA‐2A, sarco/endoplasmic reticulum Ca2+‐ATPase. **P<0.01, ***P<0.001 vs PC FA controls.

Figure 5

A, Western blot analysis showing expression of NOS‐2. Representative Western blot is shown on the top. Quantitative polymerase chain reaction analysis showing expression of (B) Nrf2, (C) SOD, (D) CAT. Data were obtained from 3‐month‐old mouse hearts (n=6 mice/group) that were born to preconception FA or PM 2.5 exposed parents and expressed as mean±SEM. CAT indicates catalase; NOS‐2, nitric oxide synthase 2; Nrf2, nuclear factor (erythroid‐derived 2)‐like 2; SOD, superoxide dismutase; PC FA, preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter). *P<0.05, **P<0.01 vs preconception FA controls.

Figure 6

Quantitative polymerase chain reaction expression of (A) IL‐6, (B) IL‐15, (C) TNF‐α, (D) NF‐κB, (E) CRP, (F) E‐selectin (CD26E), (G) P‐selectin (CD26P), (H) ICAM‐1. I, Western blot analysis showing expression of MCP‐1. Representative Western blot was shown on the right and quantification on the left. Data were obtained from 3‐month‐old mouse hearts (n=6 mice/group) that were born to preconception FA or PM 2.5 exposed parents and expressed as mean±SEM. CRP indicates C‐reactive protein; ICAM1, intercellular adhesion molecule 1; IL‐6, interleukin 6; IL‐15, interleukin 15; MCP‐1, monocyte chemoattractant protein‐1; NF‐κB, nuclear factor kappa‐light‐chain‐enhancer of activated B cells; PC FA, preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter); TNF‐α, tumor necrosis factor‐alpha. **P<0.01, ***P<0.001 vs PC FA controls.

Figure 7

A, Quantitative polymerase chain reaction expression of collagen3a1 (Col3a1) and (B) protein expression of Col3a1 via Western blot analysis. Representative Western blot is shown above and quantification below. Data were obtained from 3‐month‐old mouse hearts (n=6 mice/group) that were born to preconception FA or PM 2.5‐exposed parents and expressed as mean±SEM. PC FA indicates preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter). *P<0.05, **P<0.01 vs PC FA controls.

Figure 8

Western blot analysis showing expression of (A) DNA methyltransferases‐1 (Dnmt1) and (B) DNA methyltransferases‐3a (Dnmt3a). Representative Western blots are shown on the left and quantification on the right. Quantitative polymerase chain reaction analysis showing expression of (C) Sirt1 and (D) Sirt2. Data were obtained from 3‐month‐old mouse hearts (n=6 mice/group) that were born to preconception FA or PM 2.5‐exposed parents and expressed as mean±SEM. Dnmt1 indicates DNA methyltransferases‐1; Dnmt3a, DNA methyltransferases; PC FA, preconception filtered air; PC PM2.5, preconception particulate matter (<2.5 μm in diameter); Sirt1, sirtuin 1; Sirt2, sirtuin 2. *P<0.05, **P<0.01 vs PC FA controls.