Prenatal Exposure to Lipopolysaccharide Alters Renal DNA Methyltransferase Expression in Rat Offspring

Abstract

Prenatal exposure to inflammation results in hypertension during adulthood but the mechanisms are not well understood. Maternal exposure to lipopolysaccharide (LPS) alters interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels in the fetal environment. As reported in many recent studies, IL-6 regulates DNA methyltransferases (DNMTs) through the transcription factor friend leukemia virus integration 1 (Fli-1). The present study explores the role of intrarenal DNMTs during development of hypertension induced by prenatal exposure to LPS. Pregnant rats were randomly divided into four treatment groups: control, LPS, pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor), and the combination of LPS and PDTC. Expression of IL-6, Fli-1, TNF-α, DNMT1 and DNMT3B was significantly increased in the offspring of LPS-treated rats. Global DNA methylation level of renal cortex also increased dramatically in rat offspring of the LPS group. Prenatal PDTC administration reversed the increases in gene expression and global DNA methylation level. These findings suggest that prenatal exposure to LPS may result in changes of intrarenal DNMTs through the IL-6/Fli-1 pathway and TNF-α, which probably involves hypertension in offspring due to maternal exposure to inflammation.

Fig 1. Effects of prenatal exposure to LPS on body weight (a) and SBP (b) in rat offspring.

Data are presented as the means ± SD (n = 16 in each group; eight females and eight males). *P<0.05 and **P<0.01 compared with controls; ^ΔP<0.05 and ^ΔΔP<0.01 compared with offspring of the LPS group. CON, Control; LPS, lipopolysaccharide; PDTC, pyrrolidine dithiocarbamate; L+P, LPS+PDTC.

Fig 2. Effects of prenatal exposure to LPS on the mRNA expression of IL-6 (a, b), Fli-1 (c, d), DNMT1 (e, f), DNMT3A (g, h), and DNMT3B (i, j) in the renal cortex of rat offspring at 6 and 12 weeks of age.

Data are presented as the means ± SD (n = 6 in each group; three females and three males). *P<0.05 and **P<0.01 compared with controls; ^ΔP<0.05 and ^ΔΔP<0.01 compared with offspring of the LPS group. CON, Control; LPS, lipopolysaccharide; PDTC, pyrrolidine dithiocarbamate; L+P, LPS+PDTC.

Fig 3. Effects of prenatal exposure to LPS on the protein levels of IL-6 (a, b) and TNFα (c, d) in the renal cortex of rat offspring as determined by ELISAs.

Data are presented as the means ± SD (n = 6 in each group; three females and three males). *P<0.05 and **P<0.01 compared with controls; ^ΔP<0.05 and ^ΔΔP<0.01 compared with offspring of the LPS group. CON, Control; LPS, lipopolysaccharide; PDTC, pyrrolidine dithiocarbamate; L+P, LPS+PDTC.

Fig 4. Effects of prenatal exposure to LPS on the protein expression of Fli-1 (a, b), DNMT1 (c, d), DNMT3A (e, f), and DNMT3B (g, h) in the renal cortex of rat offspring as measured by western blotting (i) at 6 and 12 weeks of age.

Data are presented as the means ± SD (n = 6 in each group; three females and three males). *P<0.05 and **P<0.01 compared with controls; ^ΔP<0.05 and ^ΔΔP<0.01 compared with offspring of the LPS group. CON, Control; LPS, lipopolysaccharide; PDTC, pyrrolidine dithiocarbamate; L+P, LPS+PDTC.

Fig 5. Effects of prenatal exposure to LPS on the global DNA methylation level in the renal cortex of rat offspring at 6 (a) and 12 (b) weeks of age.

Data are presented as the means ± SD (n = 6 in each group; three females and three males). *P<0.05 and **P<0.01 compared with controls; ^ΔP<0.05 and ^ΔΔP<0.01 compared with offspring of the LPS group. CON, Control; LPS, lipopolysaccharide; PDTC, pyrrolidine dithiocarbamate; L+P, LPS+PDTC.