Maternal exposure to airborne particulate matter during pregnancy and lactation induces kidney injury in rat dams and their male offspring: the role of vitamin D in pregnancy and beyond

Long-Term Alterations of Renal Microvasculature in Rats Following Maternal PM2.5 Exposure: Vitamin D Effects

Background: This study aimed to investigate the long-term effects of maternal exposure to fine particulate matter (PM2.5) with or without vitamin D supplementation on the renal microvasculature in adult rat offspring. Methods: Pregnant Sprague-Dawley rats were exposed to normal saline, PM2.5, and PM2.5 with vitamin D for one month during nephrogenesis. Male offspring kidneys were taken for analyses on postnatal day 56. Results: Adult offspring rats exposed to maternal PM2.5 exhibited lower body weights and greater glomerular and tubular injury scores compared to control rats. Semi-quantitative analysis revealed a significant reduction in glomerular and peritubular capillary endothelial cells, along with a decrease in the number of glomeruli in the PM2.5 group. Maternal vitamin D supplementation reduced these changes. In offspring rats exposed to maternal PM2.5, intrarenal expression of renin, angiotensin-converting enzyme (ACE), cytochrome P450 27B1, and vascular endothelial growth factor-A (VEGF-A) increased, while expression of the vitamin D receptor, Klotho, VEGF receptor 2, angiopoietin-1, and Tie-2 decreased. Maternal vitamin D supplementation restored VEGF receptor 2 and angiopoietin-1 activities and reduced ACE and VEGF-A protein expression in adult offspring kidneys. Conclusions: Early-life exposure to PM2.5 may lead to long-term alterations in renal microvasculature and nephron loss. Maternal vitamin D supplementation during renal development can ameliorate PM2.5-induced capillary rarefaction and nephron loss in the kidneys of adult offspring.

Effects of maternal PM2.5 exposure during pregnancy on cardiovascular maldevelopment in rat offspring

BACKGROUND

Epidemiological studies suggest a link between maternal exposure to PM2.5 during pregnancy and a higher incidence of fetal cardiovascular abnormalities. However, experimental data on the underlying mechanisms remain scarce.

OBJECTIVE

This study aims to explore the effects of maternal PM2.5 exposure during pregnancy on fetal cardiovascular maldevelopment in a rat model.

METHODS

Twenty-eight pregnant rats were divided into control and PM2.5-exposed groups according the exposure doses (N = 7 per group). Rats were administered with PM2.5 suspensions corresponding to 0, 2.6, 5.5, and 11 μg/d, respectively, during gestation. On gestational day 21, neonatal hearts were collected, and levels of cardiac transcription factors (Tbx2, Tbx20, Hand2 and Gata6), MMP9, TN-C, VEGF-A, NF-κB, apoptotic markers (Bax/Bcl-2 ratio), catalase (CAT), and lipid metabolism indicators were measured.

RESULTS

In the 11 μg/d group, the mRNA levels of Tbx2, Tbx20, Hand2, Gata6, MMP9, TN-C and VEGF-A, the protein levels of Tbx2, Hand2, and TN-C, and blood CAT activity were significantly reduced (P < 0.05). Conversely, NF-κB, Bax/Bcl-2, and serum markers of dyslipidemia (TC, TG, LDH, LDL-C/HDL-C) were significantly elevated (P < 0.05). Additionally, TN-C and Hand2 mRNA levels were reduced in the 2.6 μg/d group, and LDH level was increased in the 5.5 μg/d group (P < 0.05).

CONCLUSIONS

Maternal PM2.5 exposure during pregnancy is associated with fetal cardiovascular maldevelopments, possibly through the changes of cardiac transcription factors, vascular dysfunction, oxidative stress, apoptosis, and abnormalities of lipid metabolism.

AMPK agonist AICAR ameliorates maternal hepatic lipid metabolism disorder, inflammation, and fibrosis caused by PM2.5 exposure during pregnancy

Liver is an important target organ of ambient fine particulate matter (PM2.5). Numerous studies have shown that PM2.5 exposure can cause liver lipid metabolism disorders and other liver damage in mammals. However, the impact of PM2.5 on liver health during pregnancy, a sensitive life stage, remains understudied, and the underlying mechanisms are also unknown. Given the critical role of adenosine 5'-monophosphate activated protein kinase (AMPK) in regulating lipid metabolism and inflammation, we hypothesize that AMPK activation may mitigate maternal hepatic lipid metabolism disorders, reduce inflammation, and attenuate fibrosis induced by PM2.5 exposure during pregnancy. To test this hypothesis, pregnant C57BL/6 mice were randomly assigned to 4 groups: filtered air (FA) + NS (normal saline), PM2.5+NS, FA + AICAR (acadesine, an AMPK activator), and PM2.5+AICAR. PM2.5+NS and PM2.5+AICAR groups were continuously exposed to PM2.5 with a whole-body PM2.5 exposure chamber, while the other two groups were exposed to filtered air in the FA chamber. Simultaneously, the FA + AICAR and PM2.5+AICAR groups received intraperitoneal injections of the AMPK agonist AICAR (200 mg/kg∙bw per day) from gestational day 13 (GD13) to GD17, while mice in the FA + NS and PM2.5+NS groups were administered normal saline injection. We found that gestational PM2.5 exposure induced dyslipidemia in pregnant mice, which was alleviated by AICAR treatment. Histopathological analysis showed that the exposure to PM2.5 during pregnancy induced hepatic lipid deposition and fibrosis in pregnant mice, and biochemical assays revealed that hepatic triglyceride and cholesterol levels were also significantly increased in pregnant mice after exposure to PM2.5, whereas the AICAR treatment ameliorated hepatic lipid deposition and fibrosis induced by the exposure to PM2.5 during pregnancy. Furthermore, PM2.5 exposure during pregnancy disrupted the expression of key genes and proteins associated with hepatic lipid synthesis, cholesterol synthesis, inflammation, and fibrosis, while treatment with AICAR mitigated these effects. These findings demonstrated that AMPK activation ameliorates hepatic lipid metabolism disorders, reduces inflammation, and attenuates fibrosis caused by PM2.5 exposure in mice during pregnancy. AMPK may be a target of action for maternal liver injury induced by PM2.5 exposure during pregnancy.