Exposure to airborne particulate matter induces renal tubular cell injury in vitro: the role of vitamin D signaling and renin-angiotensin system

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.

Association of acute exposure to PM2.5 constituents and sources with kidney injury: A longitudinal panel study of Nrf2 promoter polymorphism

Evidence on the effects of fine particulate matter (PM2.5) constituents and sources on kidney injury is limited. We designed a panel study with 4 repeated measurements to investigate the association of acute exposure to chemical constituents and source-specific PM2.5 with kidney function and renal tubular injury. We further evaluated the modifying effect of Nrf2 promoter polymorphism. In this study, a total of 64 participants were recruited and ambient PM2.5 constituents were monitored at a fixed-site station. We used a positive matrix factorization (PMF) model to identify emission sources and linear mixed-effect models to explore the associations. An interquartile range (IQR) increase in PM2.5 concentration was associated with a 1.40 % and 3.15 % decrease in eGFR-Cr (eGFR assessed by creatinine) and eGFR-Cys (eGFR assessed by cystatin-C), respectively, and 10.2 % higher kidney injury molecule 1 (KIM-1) levels. Carbonaceous components (EC and OC), metallic elements (Cr, K, Pb, Zn) and Cl- were robustly responsible for kidney injury. Per IQR increase in these constituents accounted for 0.57 % to 1.62 % declines in eGFR-Cr; 1.36 % to 3.66 % declines in eGFR-Cys; and 7.50 % to 19.83 % increments in KIM-1. Specific source analysis revealed that PM2.5 emitted by combustion was associated with the largest reduction in eGFR, while the secondary source played a more prominent role in renal tubular injury. The dominant models showed that the magnitudes of the effect estimates of PM2.5 and its constituents were generally larger in the participants with minor alleles of the Nrf2 promoter. These findings suggest that acute exposure to EC, OC, Cl- and several metallic constituents may be responsible for kidney injury induced by PM2.5, especially in individuals with unfavorable Nrf2 genotypes. PM2.5 from combustion and secondary sources impairs kidney health, highlighting the importance of source-oriented PM2.5 control strategies.

PM2.5 Exposure Induces Glomerular Hyperfiltration in Mice in a Gender-Dependent Manner

As one of the most common air pollutants, fine particulate matter (PM2.5) increases the risk of diseases in various systems, including the urinary system. In the present study, we exposed male and female C57BL/6J mice to PM2.5 for 8 weeks. Examination of renal function indices, including creatinine (CRE), blood urea nitrogen (BUN), uric acid (UA), and urinary microalbumin, indicated that the kidneys of female mice, not male mice, underwent early renal injury, exhibiting glomerular hyperfiltration. Meanwhile, pathological staining showed that the kidneys of female mice exhibited enlarged glomerulus that filled the entire Bowman's capsule in the female mice. Afterward, we explored the potential causes and mechanisms of glomerular hyperfiltration. Variations in mRNA levels of key genes involved in the renin-angiotensin system (RAS) and kallikrein-kinin system (KKS) demonstrated that PM2.5 led to elevated glomerular capillary hydrostatic pressure in female mice by disturbing the balance between the RAS and KKS, which in turn increased the glomerular filtration rate (GFR). In addition, we found that PM2.5 increased blood glucose levels in the females, which enhanced tubular reabsorption of glucose, attenuated macular dense sensory signaling, induced renal hypoxia, and affected adenosine triphosphate (ATP) synthesis, thus attenuating tubuloglomerular feedback (TGF)-induced afferent arteriolar constriction and leading to glomerular hyperfiltration. In conclusion, this study indicated that PM2.5 induced glomerular hyperfiltration in female mice by affecting RAS/KKS imbalances, as well as the regulation of TGF; innovatively unveiled the association between PM2.5 subchronic exposure and early kidney injury and its gender dependence; enriched the toxicological evidence of PM2.5 and confirmed the importance of reducing ambient PM2.5 concentrations.

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

BACKGROUND

Little is known about the transgenerational effects of maternal exposure to fine particulate matter (PM2.5) on offspring kidney health. This study investigated the effect of maternal administration of PM2.5 or PM2.5 with vitamin D during pregnancy and lactation on renal injury in rat dams and their offspring.

METHODS

Nine pregnant Sprague-Dawley rats received oral administration of normal saline, airborne PM2.5, or PM2.5 with vitamin D from gestational day 11 to postpartum day 21. Kidneys of rat dams (n = 3 for each group) and their male offspring (n = 5 for each group) were taken for analysis on postpartum or postnatal day 21.

RESULTS

Maternal PM2.5 exposure increased glomerular damage, tubulointerstitial injury, and cortical macrophage infiltration in both dams and pups; all increases were attenuated by vitamin D administration. In dam kidneys, PM2.5 increased the protein expression of vitamin D receptor (VDR), klotho, and tumor necrosis factor-α; vitamin D lessened these changes. The expressions of renin, nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor-kappa B (NF-κB) p50 decreased in rat dams exposed to PM2.5. In offspring kidneys, exposure to maternal PM2.5 reduced the expression of VDR, renin, angiotensin-converting enzyme (ACE), Nrf2, and NF-κB p50, but increased cytochrome P450 24A1 expression. Maternal vitamin D administration with PM2.5 enhanced VDR, ACE, and NF-κB p50 activities in pup kidneys.

CONCLUSION

PM2.5 exposure during nephrogenesis may exert transgenerational renal impairment, and maternal vitamin D intake could attenuate PM2.5-induced kidney damage in mothers and their offspring.

Associations between short-term exposure to PM2.5, NO2 and O3 pollution and kidney-related conditions and the role of temperature-adjustment specification: A case-crossover study in New York state

Epidemiologic evidence on the relationship between air pollution and kidney disease remains inconclusive. We evaluated associations between short-term exposure to PM_2.5, NO₂ and O₃ and unplanned hospital visits for seven kidney-related conditions (acute kidney failure [AKF], urolithiasis, glomerular diseases [GD], renal tubulo-interstitial diseases, chronic kidney disease, dysnatremia, and volume depletion; n = 1,209,934) in New York State (2007-2016). We applied a case-crossover design with conditional logistic regression, controlling for temperature, dew point temperature, wind speed, and solar radiation. We used a three-pollutant model at lag 0-5 days of exposure as our main model. We also assessed the influence of model adjustment using different specifications of temperature by comparing seven temperature metrics (e.g., dry-bulb temperature, heat index) and five intraday temperature measures (e.g., daily mean, daily minimum, nighttime mean), according to model performance and association magnitudes between air pollutants and kidney-related conditions. In our main models, we adjusted for daytime mean outdoor wet-bulb globe temperature, which showed good model performance across all kidney-related conditions. We observed the odds ratios (ORs) for 5 μg/m³ increase in daily mean PM_2.5 to be 1.013 (95% confidence interval [CI]: 1.001, 1.025) for AKF, 1.107 (95% CI: 1.018, 1.203) for GD, and 1.027 (95% CI: 1.015, 1.038) for volume depletion; and the OR for 5 ppb increase in daily 1-hour maximum NO₂ to be 1.014 (95% CI; 1.008, 1.021) for AKF. We observed no associations with daily 8-hour maximum O₃ exposure. Association estimates varied by adjustment for different intraday temperature measures: estimates adjusted for measures with poorer model performance resulted in the greatest deviation from estimates adjusted for daytime mean, especially for AKF and volume depletion. Our findings indicate that short-term exposure to PM_2.5 and NO₂ is a risk factor for specific kidney-related conditions and underscore the need for careful adjustment of temperature in air pollution epidemiologic studies.