Gestational exposure to PM2.5 disrupts fetal development by suppressing placental trophoblast syncytialization via progranulin/mTOR signaling.

Recent epidemiological and animal studies have indicated that ambient fine particulate matter (PM2.5) exposure during pregnancy is closely associated with intrauterine growth restriction (IUGR). However, the underlying mechanisms remain to be revealed. In this study, we found that gestational exposure to PM2.5 significantly decreased fetal weight and crown-rump length in mice, accompanied by insufficient placental trophoblast syncytialization and increased expression of progranulin (PGRN) in mice placenta. Administering PGRN neutralizing antibody to pregnant mice alleviated growth restriction and insufficient placental trophoblast syncytialization caused by PM2.5, accompanied with suppressed activation of the mTOR signaling pathway. Furthermore, in vitro experiments using human placental BeWo cells showed that 10 µg·mL-1 PM2.5 activated PGRN/mTOR signaling and suppressed forskolin-induced cell fusion, which was blocked by knockdown of PGRN. Taken together, our results demonstrated that PM2.5 exposure during pregnancy inhibited placental trophoblast syncytialization by activating PGRN/mTOR signaling, leading to abnormal placental development and IUGR. This study reveals a novel mechanism underlying the developmental toxicity of PM2.5 exposure during pregnancy.

The involvement of RNA N6-methyladenosine and histone methylation modification in decidualization and endometriosis-associated infertility.

Defective decidualization of endometrial stromal cells (ESCs) in endometriosis (EM) patients leads to inadequate endometrial receptivity and EM-associated infertility. Hypoxia is an inevitable pathological process of EM and participates in deficient decidualization of the eutopic secretory endometrium. Enhancer of zeste homology 2 (EZH2) is a methyltransferase which catalyses H3K27Me3, leading to decreased expression levels of target genes. Although EZH2 expression is low under normal decidualization, it is abundantly increased in the eutopic secretory endometrium of EM and is induced by hypoxia. Chromatin immunoprecipitation-PCR results revealed that decidua marker IGFBP1 is a direct target of EZH2, partially explaining the increased levels of histone methylation modification in defected decidualization of EM. To mechanism controlling this, we examined the effects of hypoxia on EZH2 and decidualization. EZH2 mRNA showed decreased m6 A modification and increased expression levels under hypoxia and decidualization combined treatment. Increased EZH2 expression was due to the increased expression of m6 A demethylase ALKBH5 and decreased expression of the m6 A reader protein YTHDF2. YTHDF2 directly bind to the m6 A modification site of EZH2 to promote EZH2 mRNA degradation in ESCs. Moreover, selective Ezh2 depletion in mouse ESCs increased endometrial receptivity and improved mouse fertility by up-regulating decidua marker IGFBP1 expression. This is the first report showing that YTHDF2 can act as a m6 A reader to promote decidualization by decreasing the stability of EZH2 mRNA and further increasing the expression of IGFBP1 in ESCs. Taken together, our findings highlight the critical role of EZH2/H3K27Me3 in decidualization and reveal a novel epigenetic mechanism by which hypoxia can suppress EM decidualization by decreasing the m6 A modification of EZH2 mRNA.

Desipramine ameliorates fine particulate matter-induced hepatic insulin resistance by modulating the ceramide metabolism in mice.

Recent research has highlighted a correlation between exposure to ambient fine particulate matter (PM2.5) and the development of systemic insulin resistance (IR) along with an elevated risk of diabetes. Ceramide has emerged as one of the pathogenic mechanisms contributing to IR. The inhibition of acid sphingomyelinase (ASMase) activity by desipramine (DES) has been shown to effectively reduce ceramide levels. In the present study, 24 female C57BL/6 N mice were randomized into one of the four groups: the filtered air exposure (FA) group, the concentrated PM2.5 exposure (PM) group, the concentrated PM2.5 treated with low-dose DES (DL) group, and the concentrated PM2.5 treated with high-dose DES (DH) group. The PM, DL and DH groups were exposed to PM2.5 for an 8-week period within a whole-body exposure system. The study encompassed extensive examinations of glucose homeostasis, liver lipid profile, ceramide pathway, and insulin signaling pathway. Our results demonstrated that PM2.5 exposure caused impaired glucose tolerance, elevated ceramide levels, increased phosphorylation PP2A, reduced Akt phosphorylation, and hindered GLUT2 expression. Remarkably, DES administration mitigated PM2.5-induced IR by effectively lowering ceramide levels. In conclusion, the reduction of ceramide levels by DES may be a promising therapeutic strategy for coping PM2.5-induced IR.

Gestational exposure to ambient fine particulate matter disrupts maternal hepatic lipid metabolism.

Pregnancy is a unique physiological stage for females as well as a vulnerable period for pollutant exposure. The effect of gestational ambient fine particulate matter (PM2.5) exposure on maternal lipid metabolism during pregnancy is rarely observed, and the mechanism is unknown. In the current study, pregnant C57BL/6 mice were randomly assigned to either ambient PM2.5 or filtered air exposure chambers since gestational day (GD) 0. Meanwhile, non-pregnant female mice were housed as controls in each exposure chamber. PM2.5 exposure exerted no significant effect on body weight gain or the body composition during pregnancy. Pregnant mice exposed to PM2.5 demonstrated improved glucose tolerance, whereas non-pregnant mice showed an increased fasting blood glucose level after PM2.5 exposure with no alterations in glucose tolerance. PM2.5 exposure exerted no significant effect on total lipid content in serum during pregnancy, while an increased serum total lipid level was found in non-pregnant mice exposed to PM2.5. PM2.5 exposure had no effect on total liver lipid levels, it increased several triacylglycerol (TAG) species and total cholesterol esters (CEs) in pregnant mice but lowered a considerable amount in non-pregnant mice' livers. Furthermore, gestational exposure to PM2.5 enhanced the expression of key enzymes in fatty acid uptake, de novo lipid synthesis, and ß oxidation, and inhibited molecules for lipid export in mice liver. Conversely, PM2.5 exposure upregulated proteins involved in hepatic lipolysis and lipid export in non-pregnant mice. These results suggest that the interference of PM2.5 exposure during pregnancy on the lipid metabolism, particularly the hepatic lipid metabolism, differs from that during non-pregnancy. This study provides toxicological evidence that PM2.5 exposure during pregnancy disrupts the lipid metabolism of the liver and provides a basis for protecting vulnerable populations.

Heavy metal risk of disposable food containers on human health.

The consumption of disposable materials is booming with the rapid development of urbanization and industrialization, which may inevitably cause the release of toxic and harmful substances during use of them in daily life. This study was to estimate element levels such as Beryllium (Be), Vanadium (V), Zinc (Zn), Manganese (Mn), Cadmium (Cd), Chromium (Cr), Nickel (Ni), Cobalt (Co), Antimony (Sb), Barium (Ba), Lead (Pb), Iron (Fe), Copper (Cu), and Selenium (Se) in leachate and subsequently assess the health risk of exposure to those disposable products such as paper and plastic food containers. We found that a large amount of metals was released from disposable food containers in hot water, and the order of metal concentration is Zn > Ba > Fe > Mn > Ni > Cu > Sb > Cr > Se > Be > Pb > Co > V > Cd. Additionally, the hazard quotient (HQ) of metals in young adults were less than 1, and were decreased in the order of Sb > Fe > Cu > Be > Ni > Cr > Pb > Zn > Se > Cd > Ba > Mn > V > Co. Furthermore, the excess lifetime cancer risk (ELCR) results of Ni and Be indicated that chronic exposure to Ni and Be may have a non-negligible carcinogenic risk. These findings suggest that potential health risk of metals may exist for the individuals to use disposable food containers under high temperature environment.

Research progress of omalizumab in the treatment of bullous pemphigoid.

Bullous pemphigoid (BP) is an autoimmune blistering disease associated with anti-BP180 and anti-BP230 antibodies. The pathogenic action mechanism of immunoglobulin E (IgE) antibodies in BP has been studied since the 1970s, and IgE antibodies have gradually been confirmed as being important in BP; therefore, anti-IgE therapy may be a new option for the treatment of BP. Omalizumab, as an IgE monoclonal antibody, has been increasingly used clinically to treat BP in recent years. Here, we collected 35 papers investigating omalizumab for BP treatment in a total of 83 patients, and the vast majority of patients showed varying degrees of improvement after treatment, except for a small number of patients with poor clinical outcomes. The patients were then divided into three groups according to dosing frequency and number of doses. Statistical analysis indicated that dosing frequency had little effect on clinical efficacy. While the groups with different numbers of doses were evaluated, the results concluded that clinical efficacy was affected by the number of doses, but there was no positive correlation between the number of doses and clinical efficacy.

Integrative analysis of transcriptomic and metabolomic profiles reveals abnormal phosphatidylinositol metabolism in follicles from endometriosis-associated infertility patients.

Endometriosis is a common gynecological disorder that causes female infertility. Our recent research found that excessive oxidative stress in ovaries of endometriosis patients induced senescence of cumulus granulosa cells. Here, we analyzed the transcriptomic and metabolomics profiles of follicles in a mouse model of endometriosis and in patients with endometriosis and investigated the potential function of changed metabolites in granulosa cells. RNA-sequencing indicated that both endometriosis lesions and oxidative stress in mice induced abnormalities of reactive oxidative stress, steroid hormone biosynthesis, and lipid metabolism. The mouse model and women with endometriosis showed altered lipid metabolism. Nontargeted metabolite profiling of follicular fluid from endometriosis and male-factor infertility patients by liquid chromatography mass spectrometry identified 55 upregulated and 67 downregulated metabolites. These differential metabolites were mainly involved in steroid hormone biosynthesis and glycerophospholipid metabolism. Phosphatidylinositol (PI 16:0/18:2) was significantly elevated in follicular fluid from endometriosis patients compared with controls (p < 0.05), while lysophosphatidylinositol (LPI 18:2, 20:2, 18:1, 20:3 and 18:3) was reduced (p < 0.05). Upregulated PI and downregulated LPI correlated with oocyte retrieval number and mature oocyte number. LPI inhibited cellular reactive oxidative stress induced by hemin in granulosa cells. Cell proliferation inhibition, senescence, and apoptosis induced by hemin were partially reversed by LPI. Moreover, LPI administration rescued hemin blocking of cumulus-oocyte complex expansion and stimulated expression of ovulation-related genes. Transcriptomic Switching mechanism at 5' end of the RNA transcript sequencing and western blot revealed that LPI effects on granulosa cells were associated with its regulation of MAPK-ERK1/2 signaling, which was suppressed in the presence of hemin. In conclusion, our results revealed the dysregulation of lipid metabolism in endometriotic follicles. LPI may represent a novel agent for in vitro follicular culture that reverses the excessive oxidative stress from endometriotic lesions. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Airborne PM2.5 pollution: A double-edged sword modulating hepatic lipid metabolism in middle-aged male mice.

Emerging evidence suggests that exposure to airborne fine particulate matter (PM2.5) is closely related to disturbances in hepatic lipid metabolism. However, no systematic study assessed the age vulnerability in effects of PM2.5 exposure on metabolism, and the potential mechanisms remain unknown. This study aimed to investigate the metabolic susceptibility of different life stages to PM2.5 exposure, and to evaluate the underlying molecular mechanisms. Male C57BL/6 mice at three life phases (young, adult, and middle-aged) were exposed simultaneously to concentrated ambient PM2.5 or filtered air (FA) for 8 weeks using a whole-body inhalational exposure system. The average daily PM2.5 concentrations to which mice were actually exposed were 90.71 ± 7.99 µg/m3. The body weight, total food utilization, body composition, glucose metabolic homeostasis of the mice were evaluated. At euthanasia, serum and liver samples were collected to measure lipid profiles and hepatic function. H&E and Oil Red O staining were used to assess the liver cellular structure and hepatic lipid deposition. Transcriptomics and lipidomics were performed to determine the differentially expressed genes and lipid metabolites in the liver. Quantitative RT-PCR and immunoblots were performed to verify the transcriptomics and explore the mechanism for metabolic susceptibility. PM2.5 exposure led to reductions in body weight gain, total food utilization, and fat mass in middle-aged mice but not in young or adults. Exposure to PM2.5 reduced hepatic lipid deposition by enhancing lipolysis and inhibiting the glycerol-3-phosphate (G3P) pathway of hepatic lipogenesis. Furthermore, PM2.5 exposure attenuated hepatic fatty acid metabolism and primary bile acid biosynthesis. Finally, PM2.5 exposure dysregulated hepatic phospholipid metabolism, as evidenced by increased glycerophospholipid synthesis and disturbed sphingolipid metabolism. Therefore, middle-aged male mice were more vulnerable to PM2.5 exposure with double-edged effects, improved metabolism and hepatic TG accumulation but inhibited hepatic fatty acid and bile acid metabolism and dysregulated phospholipid metabolism.

Hawthorn total flavonoids ameliorate ambient fine particulate matter-induced insulin resistance and metabolic abnormalities of lipids in mice.

Recent studies have shown a strong correlation between ambient fine particulate matter (PM2.5) exposure and diabetes risk, including abnormal lipid accumulation and systemic insulin resistance (IR). Hawthorn total flavonoids (HF) are the main groups of active substances in Hawthorn, which showed anti-hyperlipidemic and anti-hyperglycemic effects. Therefore, we hypothesized that HF may attenuate PM2.5-induced IR and abnormal lipid accumulation. Female C57BL/6 N mice were randomly assigned to the filtered air exposure (FA) group, concentrated PM2.5 exposure (PM) group, PM2.5 exposure maintained on a low-dose HF diet (LHF) group, and PM2.5 exposure maintained on a high-dose HF diet (HHF) group for an 8-week PM2.5 exposure using a whole-body exposure device. Body glucose homeostasis, lipid profiles in the liver and serum, and enzymes responsible for hepatic lipid metabolism were measured. We found that exposure to PM2.5 impaired glucose tolerance and insulin sensitivity. In addition, triacylglycerol (TAG) in serum elevated, whereas hepatic TAG levels were decreased after PM2.5 exposure, accompanied by inhibited fatty acid uptake, lipogenesis, and lipolysis in the liver. HF administration, on the other hand, balanced the hepatic TAG levels by increasing fatty acid uptake and decreasing lipid export, leading to alleviated systemic IR and hyperlipidemia in PM2.5-exposed mice. Therefore, HF administration may be an effective strategy to protect against PM2.5-induced IR and metabolic abnormalities of lipids.

Decreased Expression of EZH2 in Granulosa Cells Contributes to Endometriosis-Associated Infertility by Targeting IL-1R2.

The mechanism by which endometriosis, a common gynecological disease characterized by chronic pelvic pain and infertility, causes infertility remains elusive. Luteinized unruptured follicle syndrome, the most common type of ovulatory dysfunction, is a cause of endometriosis-associated infertility involving reduced numbers of retrieved and mature oocytes. Ovulation is controlled by luteinizing hormone and paracrine signals produced within the follicle microenvironment. Generally, interleukin (IL)-1ß is elevated in endometriosis follicular fluid, whereby it amplifies ovulation signals by activating extracellular-regulated kinase 1/2 and CCAAT/enhancer binding protein ß pathways. However, this amplification of ovulation by IL-1ß does not occur in patients with endometriosis. To illuminate the mechanism of ovulatory dysfunction in endometriosis, we analyzed the effect of oxidative stress and IL-1ß expression on endometriosis follicles. We found that oxidative stress decreased EZH2 expression and reduced H3K27Me3 levels in endometriosis ovarian granulosa cells (GCs). Selective Ezh2 depletion in mice ovarian GCs reduced fertility by disturbing cumulus-oocyte complex expansion and reducing epidermal growth factor-like factor expression. Gene expression and H3K27Me3 ChIP-sequencing (ChIP-Seq) of GCs revealed IL-1 receptor 2 (IL-1R2), a high-affinity IL-1ß-receptor that suppresses IL-1ß-mediated inflammatory cascades during ovulation, as a crucial target gene of the EZH2-H3K27Me3 axis. Moreover, IL-1ß addition did not restore ovulation upon Ezh2 knockdown, indicating a vital function of IL-1R2 in endometriosis. Thus, our findings show that reducing EZH2 and H3K27Me3 in GCs suppressed ovulatory signals by increasing IL-1R2 expression, which may ultimately contribute to endometriosis-associated infertility.

Lipidomics and transcriptomics insight into impacts of microplastics exposure on hepatic lipid metabolism in mice.

Microplastics (MPs), the emerging environmental pollutants, have attracted global attention due to the potential public health challenge and ecological security risk. Recent studies suggested liver as a vulnerable organ to MPs exposure, evidenced by abnormal hepatic lipid metabolism upon MPs intake in multiple animal species. However, the specific changes of lipid metabolism in mammalian livers, as well as the underlying mechanisms, remain to be elucidated. In the present study, C57BL/6 mice were randomly assigned to normal drinking water or drinking water containing 100 µg L-1 or 1000 µg L-1 polystyrene (PS) MPs for 8 weeks. MPs exposure exerted no significant effect on body weight, serum triglyceride or total cholesteryl esters. However, mice showed impaired glucose tolerance and hepatic lipid deposition in response to high-dose MPs administration. Further lipidomic analysis showed significant alteration in hepatic lipid species particularly with free fatty acids (FFAs) and triacylglycerols (TAGs) in mice exposed to MPs. Meanwhile, the liver transcriptional profile indicated MPs exposure-induced differentially expressed genes (DEGs) were enriched in pathways of lipid metabolism and unfolded protein response. Furthermore, most altered lipid species were significantly correlated with DEGs enriched in lipid metabolic signaling. These findings provide lipidomic and transcriptional signatures of liver in response to MPs exposure, which will shed light on further understanding of the metabolic toxicity of MPs.

Absolute quantitative lipidomics reveals lipids profiling in liver of mice with early-stage alcoholic liver disease.

BACKGROUND: Alcoholic liver disease (ALD) is one of the most prevalent chronic liver disease worldwide. Alcohol-induced alterations in hepatic lipids play an important role in ALD develpoment and progression. The present study aimed to thoroughly describe the changes of lipid profiling in liver of mice with early-stage alcoholic liver disease. METHODS: C57BL/6J male mice aged 7-week were randomized into alcohol-fed (AF) group and pair-fed control group (PF) (n = 10 per group). The early stage of ALD was induced with Lieber-DeCarli liquid diet. The lipids profiling was analyzed by absolute quantitative lipidomics with UHPLC-QTRAP-MS/MS. RESULTS: Alcohol intake significantly increased the levels of alanine aminotransferase (ALT) in plasma, and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and triacylglycerols (TAG) levels in liver. Lipidomis analyses showed that 41 TAGs were up-regulated and 8 TAGs were down-regulated in response to alcohol intake. The 8 decreased TAGs were with more double bond, longer carbon chain length and mostly contained docosahexaenoic acid (C22:6n-3) and eicosapentaenoic acid (C20:5n-3), compared with the up-regulated TAGs. Furthermore, the down-regulated TAG(56:9)_FA20:5 was inversely associated with ALT and IL-6 levels. In addition, several altered lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE) and hexosylceramides (HCER) were all significantly decreased in response to alcohol consumption, especially HCer(18:1/22:0), with the top reduction among all the down-regulated lipids. CONCLUSIONS: These findings suggest that not only the up-regulated lipids, alcohol-induced reduction in some specific lipids might also contribute to the ALD development, especially TAG(56:9)_FA20:5 and HCer(18:1/22:0). Their physiological functions and effects on ALD development warrants further investigation.

Qianjinweijing Decoction Protects Against Fine Particulate Matter Exposure-mediated Lung Function Disorder.

Fine particulate matter (PM2.5) is well known to impair lung function. Strategies protecting against PM2.5-exerted lung dysfunction have been less investigated. Qianjinweijing decoction (QJWJ), a decoction of a herbal medicine of natural origin, has been used to treat lung disorders as it inhibits oxidation and inflammation. However, no clinical trial has yet evaluated the role of QJWJ in PM2.5-induced lung dysfunction. Therefore, we conducted a randomized, double-blind, placebo-controlled trial to assess whether QJWJ provided lung benefits against the adverse effects of PM2.5 exposure among adults. Eligible participants (n = 65) were recruited and randomized to receive QJWJ decoction (n = 32) or placebo (n = 33) for 4 weeks. The restrictive ventilatory defect (RVD), lung function parameters, and induced sputum were analyzed. The PM2.5 exposure concentration was significantly associated with the vital capacity (VC), peak expiratory flow (PEF), and forced expiratory flow at 75% of the forced vital capacity (FEF75). The negative associations between PM2.5 and the lung function parameters were eliminated in response to the QJWJ intervention. Additionally, the percentage of RVD (P = 0.018) and the proportion of eosinophils (Eo%) in induced sputum (P = 0.014) in the QJWJ group was significantly lower than that in the placebo group. This study demonstrated that QJWJ could alleviated PM2.5-induced lung dysfunction and could be a potential treatment for air pollution-related chronic respiratory disease.

[Effect of electroacupuncture invention on activities of PGC-1α/Irisin (FNDC5)/BDNF signaling in cerebral cortex, hippocampus and muscles in focal cerebral ischemic/reperfusion injury rats].

OBJECTIVE: To observe the effect of electroacupuncture(EA) on the expression of peroxisome proliferator-activated receptor gamma coactivators-1-alpha (PGC-1α), Irisin and brain-derived neurotrophic factor (BDNF) in the ischemic peripheral cortex, hippocampus and local skeletal muscle in rats with focal cerebral ischemic/reperfusion injury (CI/RI), so as to explore its underlying mechanism of improving of CI/RI. METHODS: Male SD rats were randomly divided into 3 groups: sham-operation, model and EA (11 rats in each group). The focal CI/RI model was established by middle cerebral artery occlusion (MCAO). EA (2 Hz /15 Hz, 2 to 4 mA) was applied to "Quchi" (LI11) and "Zusanli" (ST36) of the affected side for 20 min, once a day for 7 days. Zea-Longa's score and Balance Beam score were used to evaluate the neurological and motor functions. The infarcted volume of the brain was detected by using 2,3,5-triphenyltetrazolium chloride staining. The expression levels of PGC-1α, fibronectin type III domain-containing protein 5(FNDC5) and BDNF proteins in the ischemic peripheral cortex, hippocampus and local skeletal muscle were detected by Western blot. RESULTS: Compared with the sham-operation group, the Zea-Longa's score, Balance Beam score, percentage of cerebral infarct volume were notably increased (P<0.01), while the expression levels of PGC-1α, FNDC5 and BDNF proteins in the cerebral cortex and hippocampus (not in the local muscle) were significantly down-regulated in the model group (P<0.01, P<0.05). In comparison with the model group, the increase of Zea-Longa's score, Balance Beam score, percentage of cerebral infarct volume, and the decrease of expression levels of PGC-1α, FNDC5 and BDNF proteins in the ischemic peripheral cortex and that of BDNF in the hippocampus were reversed in the EA group (P<0.01, P<0.05). No significant changes were found in the expression levels of hippocampal PGC-1α and FNDC5 proteins in the hippocampus and those of PGC-1α, FNDC5 and BDNF proteins in the local muscle after EA intervention (P>0.05). CONCLUSION: EA can improve neurological and motor functions and reduce cerebral infarction volume in CI/RI rats, which may be related to its functions in activating PGC-1α/Irisin(FNDC5)/BDNF pathway in the cerebral cortex.

Ambient fine particulate matter exposure disrupts placental autophagy and fetal development in gestational mice.

Recent studies have shown that some adverse pregnancy outcomes, especially intrauterine growth restriction (IUGR), are associated with gestational exposure to ambient fine particulate matter (PM2.5). However, potential mechanism remains to be elucidated. In the present study, pregnant C57BL/6 mice were randomly assigned to be exposed to either filtered air or ambient PM2.5 in the gestation period via a concentrated whole-body exposure system. We found that gestational PM2.5 exposure exerted no effect on implantation, preterm delivery, as well as fetal resorption and death. However, in utero fetal exposure to PM2.5 showed a significant reduction in body weight and crown-rump length on GD13 and GD18. Meanwhile, maternal blood sinusoid in placenta was markedly reduced along with abnormal expression of placental nutrient transporters and growth hormone in dams exposed to PM2.5. Additional tests showed gestational PM2.5 exposure decreased autophagy-related protein levels and inhibited autophagy flux mainly on GD15. Correspondingly, AMPK/mTOR signaling pathway, a critical negative regulator of autophagy, was activated in placenta on GD15 by PM2.5 exposure as well. These findings provide evidences that placental developmental disorder caused by autophagy inhibition might be an important mechanism for the growth restriction caused by PM2.5 exposure.

PM2.5 increases mouse blood pressure by activating toll-like receptor 3.

BACKGROUND AND AIMS: Plenty of literature has documented that fine particulate matter (PM2.5) exposure is related to blood pressure (BP) elevation. Vascular dysfunction is the initiation of cardiovascular diseases, such as hypertension. This thesis set out to assess the role of Toll-like receptor 3 (TLR3) in the increase in BP induced by PM2.5. METHODS: C57BL/6 and TLR3 deficient (TLR3-/-) male mice were randomly allocated to filtered air chamber or real-world inhaled concentrated PM2.5 chamber. BP was evaluated using non-invasive BP recordings. After euthanasia, the aortas and small mesenteric arteries (SMAs) were isolated, and vascular tone was measured using a wire myograph. Leucocytes were detached to assess myeloid-derived suppressor cells using flow cytometry. siRNA transfection was performed to silence TLR3 expression in the human vascular endothelial cells incubated with PM2.5. The gene expression levels of inflammation, adhesion molecules, and oxidative stress in the aortas were assessed by quantitative PCR. RESULTS: Exposure to PM2.5 increased mouse BP, and TLR3 deficiency protected against PM2.5 exposure-induced BP increase. Additionally, the injury of vascular function in the aortas and SMAs was inhibited in TLR3-/- mice. The intercellular adhesion molecule-1 (ICAM-1) was attenuated in TLR3-/- mice, accompanied by the inhibition of inflammatory and oxidized genes of the aortas, such as F4/80, interleukin-6, interleukin-1 beta, and NADPH oxidase 4. In vitro, the enhanced mRNA expression of genes encoding inflammation, oxidative stress, and ICAM-1 by PM2.5 was inhibited by TLR3 silence as well. CONCLUSIONS: PM2.5 exposure increased BP via TLR3 activation and impaired vascular function.

Ambient fine particulate matter exposure disrupts circadian rhythm and oscillation of the HPA axis in a mouse model.

Emerging evidence supports that exposure to ambient fine particulate matter (PM2.5) is associated with the metabolic syndrome. As the main neuroendocrine axis in mammals, the hypothalamic-pituitary-adrenal (HPA) axis's circadian rhythm (CR) plays an essential role in regulating metabolic homeostasis. Our previous studies found that ambient PM2.5 exposure caused CR disorder of the critical enzymes involved in lipid metabolism in mouse liver and adipose tissues. However, the impact of ambient PM2.5 exposure on the HPA axis is not fully illustrated yet. Male C57BL/6 mice were randomly exposed to ambient PM2.5 or filtered air for ten weeks via a whole-body exposure system. Rhythmic oscillations of clock genes in the hypothalamus and adrenal gland were characterized. The effects of ambient PM2.5 exposure on clock gene expression and rhythmic expression of molecules related to glucocorticoid synthesis were also examined. Firstly, a more robust CR of clock genes was demonstrated in the adrenal gland than that in the hypothalamus. Secondly, PM2.5 exposure significantly inhibited the expression of Clock at ZT8 in the hypothalamus. However, both circadian oscillation and expression levels of Bmal1, Cry1, Cry2, and Rorα were increased significantly by ambient PM2.5 exposure in the adrenal gland. Moreover, abnormal rhythmic oscillation patterns of corticotropin-releasing hormone and adrenocorticotropic hormone were observed after ambient PM2.5 exposure, with no change at the expression levels. Finally, the expression of Cyp11b1 was markedly decreased at ZT0 in the adrenal gland of PM2.5 exposed mice. Our findings provide new insights into the ambient PM2.5 exposure-induced metabolic syndrome from the perspective of CR disturbances.

Lipid metabolic adaption to long-term ambient PM2.5 exposure in mice.

Emerging evidence has demonstrated that exposure to fine particulate matter (PM2.5) is a risk factor for lipid metabolic disorders in the liver. However, the effects of PM2.5 exposure time duration on hepatic lipid metabolism remain unknown. In this study, C57BL/6 mice were randomly divided into ambient PM2.5 (PM) or filtered air (FA) exposure chamber for short-term (4 weeks) or long-term (24 weeks) exposure via a whole body exposure system. We measured hepatic triglyceride and free fatty acid levels and analyzed the alteration of lipometabolism-related molecules in the liver. We found that triglyceride levels were significantly elevated in both short-term and long-term PM2.5-exposed mice and free fatty acid levels were increased after long-term PM2.5 exposure. Besides, enzymes for lipolysis and fatty acid oxidation in the liver were inhibited after short-term PM2.5 exposure but adaptively enhanced after long-term PM2.5 exposure. Furthermore, molecules for fatty acid uptake were down-regulated in the short-term PM2.5-exposed mice whereas molecules for lipid export were induced after long-term PM2.5 exposure. Therefore, ambient PM2.5 exposure disturbed hepatic lipid metabolism and the effects varied in different exposure duration. These findings in mice provide new insight into the biological basis of PM2.5-induced human metabolic dysfunction and specific strategies may be applied based on different exposure time periods.

Sex-dependent effects of ambient PM2.5 pollution on insulin sensitivity and hepatic lipid metabolism in mice.

BACKGROUND & AIMS: Emerging evidence supports ambient fine particulate matter (PM2.5) exposure is associated with insulin resistance (IR) and hepatic lipid accumulation. In this study, we aimed to evaluate the sex-dependent vulnerability in response to PM2.5 exposure and investigate the underlying mechanism by which PM2.5 modulates hepatic lipid metabolism. METHODS: Both male and female C57BL/6 mice were randomly assigned to ambient PM2.5 or filtered air for 24 weeks via a whole body exposure system. High-coverage quantitative lipidomics approaches and liquid chromatography-mass spectrometry techniques were performed to measure hepatic metabolites and hormones in plasma. Metabolic studies, histological analyses, as well as gene expression levels and molecular signal transduction analysis were applied to examine the effects and mechanisms by which PM2.5 exposure-induced metabolic disorder. RESULTS: Female mice were more susceptible than their male counterparts to ambient PM2.5 exposure-induced IR and hepatic lipid accumulation. The hepatic lipid profile was changed in response to ambient PM2.5 exposure. Levels of hepatic triacylglycerols (TAGs), free fatty acids (FFAs) and cholesterol were only increased in female mice from PM group compared to control group. Plasmalogens were dysregulated in the liver from PM2.5-exposed mice as well. In addition, exposure to PM2.5 led to enhanced hepatic ApoB and microsomal triglyceride transport protein expression in female mice. Finally, PM2.5 exposure inhibited hypothalamus-pituitary-adrenal (HPA) axis and decreased glucocorticoids levels, which may contribute to the vulnerability in PM2.5-induced metabolic dysfunction. CONCLUSIONS: Ambient PM2.5 exposure inhibited HPA axis and demonstrated sex-associated differences in its effects on IR and disorder of hepatic lipid metabolism. These findings provide new mechanistic evidence of hormone regulation in air pollution-mediated metabolic abnormalities of lipids and more personalized care should be considered in terms of sex-specific risk factors.

Ambient fine particulate matter disrupts hepatic circadian oscillation and lipid metabolism in a mouse model.

Emerging evidence has shown that exposure to ambient fine particulate matter (PM2.5) is associated with hepatic lipid accumulation. However, the underlying mechanism is not fully characterized yet. Autonomous circadian clock in the liver plays a fundamental role in maintaining lipid metabolism homeostasis. In this study, we evaluated the effects of ambient PM2.5 exposure on the expression of hepatic circadian clock genes and expression rhythm of genes associated with lipid metabolism in mice liver. Male C57BL/6 mice were randomly assigned to ambient PM2.5 or filtered air for 10 weeks via a whole body exposure system. We found that the liver mass was reduced significantly at zeitgeber time (ZT) 8 in mice exposed to PM2.5 but not levels or circadian rhythm of hepatic triglycerides or free fatty acid (FFA). In addition, exposure to PM2.5 led to enhanced expression of bmal1 at ZT0/24, cry1 at ZT16 and rev-erbα at ZT4 and ZT8. Furthermore, the expression of pparα was enhanced in mice liver at ZT4 and ZT8 after PM2.5 exposure, with upregulation of pparα-mediated genes responsible for fatty acid transport and oxidation. Finally, the expression of rate-limiting enzymes for lipid synthesis was all significantly increased in the liver of PM2.5 exposed mice at ZT12. Therefore, the present study provides new perspectives for revealing the etiology of hepatic lipid metabolism abnormality from PM2.5-induced circadian rhythm disorder.