Epigenetics of Notch1 regulation in pulmonary microvascular rarefaction following extrauterine growth restriction.

BACKGROUND: Extrauterine growth restriction (EUGR) plays an important role in the developmental origin of adult cardiovascular diseases. In an EUGR rat model, we reported an elevated pulmonary arterial pressure in adults and genome-wide epigenetic modifications in pulmonary vascular endothelial cells (PVECs). However, the underlying mechanism of the early nutritional insult that results in pulmonary vascular consequences later in life remains unclear. METHODS: A rat model was used to investigate the physiological and structural effect of EUGR on early pulmonary vasculature by evaluating right ventricular systolic pressure and pulmonary vascular density in male rats. Epigenetic modifications of the Notch1 gene in PVECs were evaluated. RESULTS: EUGR decreased pulmonary vascular density with no significant impact on right ventricular systolic pressure at 3 weeks. Decreased transcription of Notch1 was observed both at 3 and 9 weeks, in association with decreased downstream target gene, Hes-1. Chromatin immunoprecipitation and bisulfite sequencing were performed to analyze the epigenetic modifications of the Notch1 gene promoter in PVECs. EUGR caused a significantly increased H3K27me3 in the proximal Notch1 gene promoter, and increased methylation of single CpG sites in the distal Notch1 gene promoter, both at 3 and 9 weeks. CONCLUSIONS: We conclude that EUGR results in decreased pulmonary vascular growth in association with decreased Notch1 in PVECs. This may be mediated by increased CpG methylation and H3K27me3 in the Notch1 gene promoter region.

Epigenetics of hyper-responsiveness to allergen challenge following intrauterine growth retardation rat.

BACKGROUND: Epidemiological studies have revealed that intrauterine growth retardation (IUGR) or low birth weight is linked to the later development of asthma. Epigenetic regulatory mechanisms play an important role in the fetal origins of adult disease. However, little is known regarding the correlation between epigenetic regulation and the development of asthma following IUGR. METHODS: An IUGR and ovalbumin (OVA)-sensitization/challenge rat model was used to study whether epigenetic mechanisms play a role in the development of asthma following IUGR. RESULTS: Maternal nutrient restriction increased histone acetylation levels of the endothelin-1 (ET-1) gene promoter in lung tissue of offspring, but did not cause significant alterations of DNA methylation. The effect was maintained until 10 weeks after birth. Furthermore, these epigenetic changes may have induced IUGR individuals to be highly sensitive to OVA challenge later in life, resulting in more significant changes related to asthma. CONCLUSIONS: These findings suggest that epigenetic mechanisms might be closely associated with the development of asthma following IUGR, providing further insight for improved prevention of asthma induced by environmental factors.

Decreased Kv1.5 expression in intrauterine growth retardation rats with exaggerated pulmonary hypertension.

Chronic hypoxia pulmonary hypertension (CH-PHT) in adulthood is likely to be of fetal origin following intrauterine growth retardation (IUGR). Oxygen (O2)-sensitive voltage-gated potassium channels (Kv channels) in resistance pulmonary artery smooth muscle cells (PASMCs) play an important role in scaling pulmonary artery (PA) pressure. Expression and functional changes of Kv channels are determined, in part, by embryonic development. We hypothesized that O2-sensitive Kv channels play an important role in exaggerated CH-PHT following IUGR. We established a rat model of IUGR by restricting maternal food during the entire pregnancy and exposed IUGR rats and their age-matched controls aged 12 wk to hypoxia for 2 wk. We found that hypoxia exposure significantly induced increased PA pressure and thicker smooth muscle layer in the IUGR group relative to controls. We compared the constriction of the resistance PA to inhibitors of K⁺ channels, 4-aminopyridine (4-AP), tetraethylammonium, and BaCl2. Despite the thickness of the smooth muscle layer, the constriction to 4-AP was significantly reduced in the IUGR group exposed to hypoxia. Consistent with these changes in pulmonary vascular reactivity, 2 wk of hypoxia induced weaker 4-AP-sensitive Kv currents in a single IUGR PASMC. Moreover, after 2 wk of hypoxia, Kv1.5 expression in resistance PAs decreased significantly in the IUGR group. Overexpression of Kv1.5 in cultured PASMCs could offset hypoxia-induced cell proliferation and hypoxia-inhibited Kv currents in the IUGR group. These results suggest that the inhibited expression of Kv1.5 in PASMCs contribute to the development of exaggerated CH-PHT in IUGR rats during adulthood.

Expression of vascular endothelial growth factor C correlates with lymphatic vessel density and prognosis in human gastroesophageal junction carcinoma.

BACKGROUND: The present study clarifies the clinical significance of vascular endothelial growth factor C (VEGF-C) in patients with gastroesophageal junction carcinoma treated with curative resection, as well as the correlation between VEGF-C expression and lymphatic vessel density (LVD). PATIENTS AND METHODS: VEGF-C expression was immunohistochemically detected in 128 patients with gastroesophageal junction carcinoma, who underwent curative surgical resection. The mean optical density (MOD) was measured to represent the expression level of VEGF-C. The lymphatic vessels were labeled with D2-40 to calculate LVD. The association between MOD and LVD and clinicopathological parameters as well as the prognosis were analyzed. RESULTS: Both VEGF-C expression and LVD were correlated with nodal metastasis and clinical stage (p < 0.05). For the high (MOD > 0.18) and low (MOD ≤ 0.18) VEGF-C group, the mean LVD was 16.9 ± 5.96 and 13.6 ± 5.58, respectively (p = 0.002), and the mean number of positive resected lymph nodes was 2.9 ± 2.44 and 2.0 ± 2.36, respectively (p = 0.025). For the high (LVD > 13) and low (LVD ≤ 13) LVD group, the mean number of positive resected lymph nodes was 3.0 ± 2.34 and 1.9 ± 2.43, respectively (p = 0.010). In univariate analysis, both high expression of VEGF-C and a high LVD level were statistically associated with poor disease-free survival (p = 0.000). Multivariate analysis showed that VEGF-C, nodal metastasis, depth of tumor invasion, postoperative chemotherapy, and resection extent were independent survival predictors (p < 0.05). CONCLUSIONS: Increased expression of VEGF-C is correlated with high levels of LVD and poorer treatment outcome.