The structural and functional effects of fine particulate matter from cooking oil fumes on rat umbilical cord blood vessels

Subacute PM2.5 Exposure Induces Hepatic Insulin Resistance Through Inflammation and Oxidative Stress

Epidemiological studies prove that type II diabetes, characterized by insulin resistance (IR), may be caused by fine particulate matter 2.5 (PM2.5). However, underlying mechanisms whereby PM2.5, particularly during short-term exposure, induces liver dysfunction leading to IR remains poorly understood. In the present study, HepG2 cells and the BALB/c mouse model were used to explore how PM2.5 affects insulin sensitivity. The effects of subacute PM2.5 exposure on glucose metabolism were examined using commercial kits. Oxidative stress and inflammation were detected by fluorescent staining and RT-qPCR. The phosphorylation of PI3K/AKT was examined by Western blot. Subacute PM2.5 exposure induced IR, as reflected by increased glucose levels in cell supernatants, elevated insulin levels, and the impaired intraperitoneal glucose tolerance test in mice. PM2.5 induced oxidative stress, as evidenced by increased reactive oxygen species, cytochrome P450 2E1, and malondialdehyde, along with reduced superoxide dismutase 1/2 and silent information regulator 1. IL-6 and TNF-α were found to be upregulated using RT-qPCR. Western blot showed that PM2.5 inhibited the PI3K-AKT signaling pathway, indicated by the decreased phosphorylation of PI3K/AKT in HepG2 cells. Additionally, H&E staining showed only mild hepatic injury in mice liver. These results firmly suggest that subacute PM2.5 exposure induces insulin resistance through oxidative stress, inflammation, and the inhibition of the PI3K-AKT signaling pathway.

Role of ROS-mediated PERK/ATF4 signaling activation in extracorporeal tube formation injury of human umbilical vein endothelial cells induced by cooking oil fume PM2.5 exposure

Cooking oil fume-derived PM2.5 (COF-PM2.5) is a major source of indoor air contamination in China, which has been demonstrated to be a hazard factor of cardiovascular and cerebrovascular diseases. This study aimed to investigate the role of ROS-mediated PERK/ATF4 signaling activation in COF-PM2.5-inhibited extracorporeal tube formation in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with 100 μg/mL COF-PM2.5 at different times, with or without 100 nM PERK activity inhibitor GSK2606414 (GSK) or 200 μM antioxidant N-acetylcysteine (NAC) pretreatment. Our results showed that COF-PM2.5 exposure can inhibit extracorporeal tube formation and down-regulate VEGFR2 expression in HUVECs. Furthermore, our data indicated that COF-PM2.5 exposure can activate the PERK/ATF4 signaling in HUVECs. Mechanistically, pretreatment with GSK interdicted PERK/ATF4 signaling, thereby reversing COF-PM2.5-downregulated VEGFR2 protein expression in HUVECs. Furthermore, NAC reversed VEGFR2 expression downregulated induced by COF-PM2.5 by inhibiting the upregulation of intracellular ROS levels and PERK/ATF4 signaling in HUVECs. As above, COF-PM2.5 exposure could induce ROS release from HUVECs, which in turn activate the endoplasmic reticulum PERK/ATF4 signaling and inhibit tube formation of HUVECs.

Vitamin D3 protects intrauterine growth restriction induced by cooking oil fume derived fine particulate matters

BACKGROUND

Cooking oil fume (COF) is an important source of indoor air pollution which severely affects human health, and sufficient vitamin D₃ (VitD₃) is necessary for maternal and child health. However, the effects of cooking oil fume-derived PM_2.5 (COF-PM_2.5) on birth outcomes and whether VitD₃ could protect from adverse effects caused by COFs-PM_2.5 are still unclear.

METHODS

Twenty-four pregnant rats were divided into 4 groups and treated with various treatments: normal feeding, COFs-PM_2.5 intratracheal instillation, VitD₃ intragastric administration, and COFs-PM_2.5 and VitD₃ co-treatment, respectively. The fetal rats were obtained in pregnant 21 days and the development of them was recorded. Morphological changes in umbilical cord were measured with HE staining, and the oxidative stress and inflammatory levels were also investigated. Western blotting and RT-PCR was used to detect the expression of angiogenesis related factors.

RESULTS

We successfully established an intrauterine growth restriction model in rats induced by COFs-PM_2.5 where fetus weight significantly decreased after COFs-PM_2.5 exposure. As for the umbilical cord vasculature, the wall thickened and the lumen narrowed down, and the contractility of the umbilical cord vasculature enhanced after COFs-PM_2.5 exposure. COFs-PM_2.5 exposure also increased the oxidative stress and inflammation level and activated the HIF-1α/eNOS/NO and VEGF/VEGFR2/eNOS signaling pathway. Interestingly, VitD₃ intervention significantly increased the fetus weight and attenuated the injury of umbilical cord vascular, and partly or completely reversed the changes in the ROS/eNOS/ET-1 axis caused by COF-PM_2.5.

CONCLUSIONS

The findings of this study suggested that COF-PM_2.5 exposure could contribute to intrauterine growth restriction through disturbing the ROS/eNOS/ET-1 axis, while VitD₃ supplementation could be an effective prophylactic measurement.

NADPH oxidases regulate endothelial inflammatory injury induced by PM2.5 via AKT/eNOS/NO axis

Fine particulate matter (PM_2.5 )-induced detrimental cardiovascular effects have been widely concerned, especially for endothelial cells, which is the first barrier of the cardiovascular system. Among potential mechanisms involved, reactive oxidative species take up a crucial part. However, source of oxidative stress and its relationship with inflammatory response have been rarely studied in PM_2.5 -induced endothelial injury. Here, as a key oxidase that catalyzes redox reactions, NADPH oxidase (NOX) was investigated. Human umbilical vein endothelial cells (EA.hy926) were exposed to Standard Reference Material 1648a of urban PM_2.5 for 24 h, which resulted in NOX-sourced oxidative stress, endothelial dysfunction, and inflammation induction. These are manifested by the up-regulation of NOX, increase of superoxide anion and hydrogen peroxide, elevated endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA) level, reduced nitric oxide (NO) production, and down-regulation of phosphorylation of endothelial NO synthase (eNOS) with increased levels of inducible NO synthase, as well as the imbalance between tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1), and changes in the levels of pro-inflammatory and anti-inflammatory factors. However, administration of NOX1/4 inhibitor GKT137831 alleviated PM_2.5 -induced elevated endothelial dysfunction biomarkers (NO, ET-1, ADMA, iNOS, and tPA/PAI-1), inflammatory factors (IL-1β, IL-10, and IL-18), and adhesion molecules (ICAM-1, VCAM-1, and P-selectin) and also passivated NOX-dependent AKT and eNOS phosphorylation that involved in endothelial activation. In summary, PM_2.5 -induced NOX up-regulation is the source of ROS in EA.hy926, which activated AKT/eNOS/NO signal response leading to endothelial dysfunction and inflammatory damage in EA.hy926 cells.

Melatonin regulates the functional components of photosynthesis, antioxidant system, gene expression, and metabolic pathways to induce drought resistance in grafted Carya cathayensis plants

The Chinese hickory (Carya cathayensis) is an economically important tree species popular for its nuts. However, the tree requires a long time to reach the nut-producing phase. To overcome this problem, grafting is widely used to reduce the time from the vegetative to the reproductive phase. This tree species also faces many environmental challenges due to climate change; drought is an important factor affecting growth and development. Here, we designed an experiment to assess the protective efficiency of melatonin in grafted Chinese hickory plants under drought stress. The results revealed that exogenously applied melatonin successfully recovered the growth of grafted Chinese hickory plants and improved photosynthetic efficiency. Exogenously applied melatonin also boosted the antioxidative defense system of the plants under drought stress, resulting in enhanced reactive oxygen species (ROS) scavenging. The accumulation of compatible solutes such as total soluble sugars and proline was also triggered by melatonin. Moreover, the analyses using metabolomics revealed that drought-stressed plants treated with melatonin regulated key metabolic pathways such as phenylpropanoid, chlorophyll and carotenoid biosynthesis, carbon fixation, and sugar metabolism. To further validate the physiological, biochemical, and metabolomic factors, we studied the molecular mechanisms by analyzing the expression of key genes involved in chlorophyll metabolism (chlorophyllase, CHLASE), antioxidative defense (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; peroxidase, POD), and phenylalanine ammonia-lyase (PAL). Exogenously applied melatonin significantly regulated the transcript levels of key genes involved in the biological processes mentioned above. Melatonin also showed crosstalk with other hormones (zeatin, gibberellin A14, 24-epibrassinolide, jasmonic acid, and abscisic acid) to regulate the physiological processes. The results of this study show that melatonin regulates biological processes at the metabolic and molecular levels to resist drought stress.

Toxicity of cooking oil fume derived particulate matter: Vitamin D3 protects tubule formation activation in human umbilical vein endothelial cells

Cooking oil fumes-derived PM_2.5 (COFs-derived PM_2.5) is the main source of indoor pollution. Exposure to COFs-derived PM_2.5 can cause oxidative stress and affect angiogenesis. Here we investigated the roles of vitamin D₃ (VD₃) in protecting tubule formation injury induced by COFs-derived PM_2.5, and the roles of ROS/NLRP3/VEGF signaling pathway in the effects. Human umbilical vein endothelial cells (HUVECs) were exposed to 0 (1‰ DMSO), 1000 nmol/l VD₃, 100 μg/ml PM_2.5, and 1000 nmol/l VD₃ + 100 μg/ml PM_2.5, respectively. Cell viability and tube formation, as well as protein and mRNA levels were measured. The results showed that exposure of COFs-derived PM_2.5 dose-and time-dependently reduced the viability of HUVECs, increased the levels of mitochondrial and intracellular ROS, and changed the mitochondrial membrane potential level. While co-incubation with VD₃ rescued these adverse effects. Both Western blot and real-time PCR (RT-PCR) showed that the expressions of NLRP3, caspase-1, Interleukin (IL)-1β, and IL-18 in COFs-derived PM_2.5 exposure group increased significantly, which could be effectively decreased by co-incubation with VD₃. COFs-derived PM_2.5 exposure could also reduce the expression of VEGF, while co-incubating HUVECs with VD₃ evidently up-regulated the protein level of VEGF in HUVECs. In addition, COFs-derived PM_2.5 could also inhibit the tube formation of HUVECs in vitro, which could be effectively rescued by the co-incubation of VD₃. Our study proved that COFs-derived PM_2.5 could damage the tubule formation of HUVECs in vitro, which could be effectively rescue by co-incubation with VD₃, in which processes the ROS/NLRP3/VEGF signaling pathway played a crucial role. It provides a new theoretical basis for further study on the toxicity of PM_2.5 to umbilical cord blood vessels.

Maternal Exposure to PM2.5 Affects Fetal Lung Development at Sensitive Windows

Lung development continues from the embryonic period to adulthood. Previous epidemiological studies have noted that maternal exposure of atmospheric pollutants during the sensitive windows disturbed the lung development and increased the risk of lung diseases after birth, but the experimental evidence was insufficient. In the present study, we exposed plug-positive mice to PM2.5 (3 mg/kg b.w.) by oropharyngeal aspiration every other day, and intended to test whether maternal PM2.5 exposure affected prenatal lung development in the offspring. First, maternal PM2.5 exposure decreased embryo weight and crown-rump length at E18.5 but not in earlier developmental stages (E0-E16.5). Second, maternal PM2.5 exposure did not prevent lung-bud and tracheal specification, and did not cause abnormalities in branching morphogenesis, distal lung epithelium, and mesenchyme differentiation in earlier stages of lung development (E0-E16.5). However, the exposure significantly disturbed the distal lung epithelium and mesenchyme differentiation of lung, led to reduced intact rings of trachea, and suppressed the expression of lung development-related genes (Nkx2.1, Tbx4, Tbx5, and Sox9) at E18.5. Finally, we found that the exposure not only increased PM2.5-bound metal content (Pb and Cu) but also caused inflammatory response in the placenta, which transmitted from the mother to the fetus and contributed to the developmental abnormalities.

Melatonin Stimulates Activities and Expression Level of Antioxidant Enzymes and Preserves Functionality of Photosynthetic Apparatus in Hickory Plants (Carya cathayensis Sarg.) under PEG-Promoted Drought

Nowadays, drought is one of the major abiotic factors which negatively affects growth and development of several fruit tree species, including Chinese hickory plants (Carya cathayensis Sarg.). The present investigation was conducted to study the possible positive effects of melatonin in drought resistance of C. cathayensis plants along with associated mechanisms. It was observed that melatonin pre-treatment applied before limited water availability significantly contrasted drought-promoted negative effects in terms of plant growth and physiological responses. Significant improvement was observed in key biological parameters like relative water content, net photosynthetic rate, stomatal conductance, transpiration rate, maximum photosynthetic efficiency of photosystem II (PSII), and PSII electron transport rate. Antioxidant apparatus was also stimulated by melatonin and enhanced activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) were noticed along with higher accumulation of proline. Gene expression studies herein revealed that melatonin promoted the up-regulation of the expression of SOD (70.7%), CAT (32.7%), and APX (66.5%) genes. As a consequence, accumulation of malondialdehyde by-products and leaf symptoms were reduced in melatonin-treated plants. All these observations offer the clear evidence that pre-treatment with melatonin ameliorate the performance of Chinese hickory plants against drought stress.

Effects of cooking oil fume derived fine particulate matter on blood vessel formation through the VEGF/VEGFR2/MEK1/2/ERK1/2/mTOR pathway in human umbilical vein endothelial cells

In China, cooking oil fume derived fine particulate matter (COF-derived PM_2.5) is a principal source of indoor air pollution. Here, we investigated cytotoxicity of COF-derived PM_2.5, as well as the roles of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR cascade in the inhibitory effects of COF-derived PM_2.5, on angiogenesis in human umbilical vein endothelial cells (HUVECs). After exposure to COF-derived PM_2.5, cell viability and tube formation, as well as protein and mRNA levels of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR in HUVECs were measured. Cell viability and number of tubes reduced dose-dependently after COF-derived PM2.5 and SU5416 treatment. In addition, SU5416 and VEGF significantly affected tube formation. The protein and mRNA levels of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR all tended to reduce with the increase of COF-derived PM2.5 concentrations. These findings demonstrate that VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR play key roles in COF-derived PM_2.5 induced inhibition of angiogenesis in HUVECs.

The effects of cooking oil fumes-derived PM2.5 on blood vessel formation through ROS-mediated NLRP3 inflammasome pathway in human umbilical vein endothelial cells

BACKGROUND

Cooking oil fumes (COFs), a main pollutant in kitchen air, is a major risk to human health. In our previous research, exposure to COFs-derived PM_2.5 could cause umbilical vascular endothelial dysfunction, leading to decreased fetal weight. Here, to test the role of ROS-mediated NLRP3 inflammasome pathway in blood vessel formation of human umbilical vein endothelial cells (HUVECs) caused by COFs-derived PM_2.5, the cells were exposed to COFs-derived PM_2.5 at different concentrations with and without N-acetyl-L-cysteine (NAC).

METHODS

MTT assay was used to determine HUVECs viability. Intracellular ROS and mitochondrial ROS levels were assessed with DCFH-DA and MitoSOX™ assay. The levels of proteins and mRNA involved in NLRP3 inflammasome signaling pathway and VEGF were measured by western blot and real-time PCR (RT-PCR). Tube formation in HUVECs was detected by tube formation assay.

RESULTS

The results revealed that COFs-derived PM_2.5 exposure reduced HUVECs viability, increased the intracellular and mitochondrial ROS levels in cells, and up-regulated the levels of proteins and mRNA involved in NLRP3 inflammasome signaling pathway. However, the protein and mRNA expression of VEGF were reduced with the increasing exposure concentrations. In addition, COFs-derived PM_2.5 also affected the tube formation. However, co-incubation with NAC effectively rescued the damages caused by COFs-derived PM_2.5 exposure.

CONCLUSIONS

This study proved that COFs-derived PM_2.5 could significantly reduce HUVECs viability, induce the overproduction of ROS, lead to inflammation and inhibit VEGF expression, thus affect angiogenesis of HUVECs in vitro. It was revealed that the impact caused by COFs-derived PM_2.5 on blood vessel formation through a ROS-mediated NLRP3 inflammasome pathway.

The emission of PM2.5 in respiratory zone from Chinese family cooking and its health effect

To investigate the PM_2.5 emission in the direct exposed area from Chinese family cooking, eleven kinds of Chinese ordinary family cooking dishes were designed including frying, quick-frying, stewing, deep-frying, boiling and steaming according to the results of questionnaire survey. The results showed that the intensity sequence for PM_2.5 emissions decreased as follows in general: deep-frying (0.709-2.731 mg/m³) > stir-frying (0.700-0.958 mg/m³) > stewing (~0.573 mg/m³) > quick-frying (0.140-0.433 mg/m³) > boiling (0.004-0.247 mg/m³) > steaming (0.011-0.088 mg/m³), most of them exceeded the national indoor air standard. The average concentration of PM_2.5 in the direct respiratory zone from family cooking was determined to be 0.599 mg/m³, which was about 8 times higher than the national indoor air standard of China and lower than that from commercial restaurants. The annual PM_2.5 inhalation exposure in the direct exposed area from family cooking for male and female was 346.30 mg/year and 309.59 mg/year, respectively. Although the annual PM_2.5 inhalation exposure of male operators in general ordinary family cooking was about 11.8% higher than that of females, the pregnant women, children and the elderly are not encouraged to prepare ordinary family cooking for a long time due to their sensitive to PM_2.5 emission. Selecting ventilator with high wind speed can reduce PM_2.5 emission more than 65% when compared to medium wind speed. Improvement of ventilator wind speed is considered to be an effect way to reduce PM_2.5 emission for cooking.

Association between prenatal exposure to cooking oil fumes and full-term low birth weight is mediated by placental weight

OBJECTIVE

Evidence regarding the association between prenatal exposure to cooking oil fumes (COF) and full-term low birth weight (FTLBW) is still controversial, and the mechanism remains unclear. This study thus aims to explore the association of prenatal COF exposure with off-spring FT-LBW as well as the mediating role of placenta in their association.

METHODS

A case-control study enrolling 266 pregnant women delivering FTLBW newborns (cases) and 1420 delivering normal birth weight (NBW) newborns (controls) was conducted. Information on prenatal COF exposure, socio-demographics, and obstetric conditions were collected at the Women's and Children's Hospitals of Shenzhen and Foshan in Guangdong, China. Linear and hierarchical logistic regression models were undertaken to explore the associations among COF exposure, placenta and birth weight, as well as the mediation effect of placental weight.

RESULTS

After controlling for potential confounders, prenatal COF exposure was significantly associated with the higher risk of FT-LBW (OR = 1.31, 95% CI= 1.06-1.63) and the lower placental weight (ß = -0.12, 95% CI= -0.23 ~ -0.005). Compared with mothers who never cooked, those cooking sometimes (OR= 2.99, 95% CI= 1.48-6.04) or often (OR= 3.41, 95% CI= 1.40-8.34) showed a higher risk of FT-LBW, and likewise, those cooking for less than half an hour (OR= 2.08, 95% CI= 1.14-3.79) or cooking between half to an hour (OR= 2.48, 95% CI= 1.44-4.29) were also more likely to exhibit FT-LBW. Different cooking methods including pan-frying (OR= 2.24, 95% CI= 1.30-3.85) or deep-frying (OR= 1.78, 95% CI= 1.12-2.85) during pregnancy were associated with increased FT-LBW risks as well. The further mediation analysis illustrated that placental weight mediated 15.96% (95% CI: 12.81~28.80%) and 15.90% (95% CI= 14.62%~16.66%) of the associations of cooking during pregnancy and frequency of prenatal COF exposure, respectively, with FT-LBW.

ROS-AKT-mTOR axis mediates autophagy of human umbilical vein endothelial cells induced by cooking oil fumes-derived fine particulate matters in vitro

Cooking oil fumes-derived PM_2.5 (COFs-derived PM_2.5) exposure can induce oxidative stress and cytotoxic effects. Here we investigated the role of ROS-AKT-mTOR axis in COFs-derived PM_2.5-induced autophagy in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with different concentrations of COFs-derived PM_2.5, together with or without N-acetyl-L-cysteine (NAC, a radical scavenger) or 3-methyladenine (3-MA, an autophagy inhibitor). Cell viability was assessed with MTT assay, and ROS level was measured with DCFH-DA assay after the treatment. Transmission electron microscopy (TEM) was used to evaluate the formation of autophagosomes, while immunofluorescent assay and western blot were used to assess the expression of LC3-I/II and beclin 1. Proteins involved in the PI3K-AKT-mTOR signaling pathway were measured with western blot. The results showed that the treatment of COFs-derived PM_2.5 dose-dependently reduced the viability of HUVECs and increased the ROS levels in the cells. Both immunofluorescent assay and western blot showed that treatment with COFs-derived PM_2.5 significantly increased LC3-II and beclin 1 levels, as well as the ratio of LC3-II/LC3-I, which could be rescued by the co-incubation with NAC or 3-MA. TEM also confirmed the increased formation of autophagosomes in the cells treated with COFs-derived PM_2.5, while co-treatment with NAC evidently decreased autophagosomes formation. In addition, western blot also showed that the phosphorylation of PI3K, AKT, and mTOR all decreased by the treatment of COFs-derived PM_2.5, which was effectively rescued by the co-treatment with NAC. These findings demonstrate ROS-AKT-mTOR axis plays a critical role in HUVECs autophagy induced by COFs-derived PM_2.5.

The injury of fine particulate matter from cooking oil fumes on umbilical cord blood vessels in vitro

Cooking oil fumes (COFs) derived PM_2.5 is the major source of indoor air pollution in Asia. For this, a pregnant rat model within different doses of cooking oil fumes (COFs) derived PM_2.5 was established in pregnancy in our research. Our previous studies have showed that exposure to COFs-derived PM_2.5 was related to adverse pregnancy outcomes. However, the mechanisms of signaling pathways remain unknown. Therefore, this study aimed to investigate the underlying mechanisms induced by COFs-derived PM2.5 injury on umbilical cord blood vessels (UCs) in vitro. Exposure to COFs-derived PM_2.5 resulted in changing the expression of eNOS, ET-1, ETRA, and ETRB. In additions, western blot analysis indicated that the HIF-1α/iNOS/NO signaling pathway and VEGF/VEGFR1/iNOS signaling pathway were involved in UCs injury triggered by COFs-derived PM_2.5. In conclusion, our data suggested that exposure to COFs-derived PM_2.5 resulted in increasing of oxidative stress and inflammation, as well as dysfunction of UCs.