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.
Display omitted
•PM2.5 exposure altered the expression pattern or level of core circadian clock genes in mouse liver.•PM2.5 exposure disrupted the rhythms of key transcription factors in hepatic lipid metabolism.•PM2.5 exposure disrupted the rhythms of the key enzymes involved in hepatic lipid metabolism.
Perturbing hepatic circadian oscillations and lipid metabolism with ambient fine particulate matter exposure.
Emerging evidence supports ambient fine particulate matter (PM.sub.2.5) 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 PM.sub.2.5 exposure and investigate the underlying mechanism by which PM.sub.2.5 modulates hepatic lipid metabolism. Both male and female C57BL/6 mice were randomly assigned to ambient PM.sub.2.5 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 PM.sub.2.5 exposure-induced metabolic disorder. Female mice were more susceptible than their male counterparts to ambient PM.sub.2.5 exposure-induced IR and hepatic lipid accumulation. The hepatic lipid profile was changed in response to ambient PM.sub.2.5 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 PM.sub.2.5-exposed mice as well. In addition, exposure to PM.sub.2.5 led to enhanced hepatic ApoB and microsomal triglyceride transport protein expression in female mice. Finally, PM.sub.2.5 exposure inhibited hypothalamus-pituitary-adrenal (HPA) axis and decreased glucocorticoids levels, which may contribute to the vulnerability in PM.sub.2.5-induced metabolic dysfunction. Ambient PM.sub.2.5 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.
Recent research has highlighted a correlation between exposure to ambient fine particulate matter (PM
) 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 PM
exposure (PM) group, the concentrated PM
treated with low-dose DES (DL) group, and the concentrated PM
treated with high-dose DES (DH) group. The PM, DL and DH groups were exposed to PM
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 PM
exposure caused impaired glucose tolerance, elevated ceramide levels, increased phosphorylation PP2A, reduced Akt phosphorylation, and hindered GLUT2 expression. Remarkably, DES administration mitigated PM
-induced IR by effectively lowering ceramide levels. In conclusion, the reduction of ceramide levels by DES may be a promising therapeutic strategy for coping PM
-induced IR.
The disruption of circadian rhythms (CRs) has been linked to metabolic disorders, yet the role of hepatic BMAL1, a key circadian regulator, in the whole-body metabolism and the associated lipid ...metabolic phenotype in the liver remains unclear. Bmal1 floxed (Bmal1f/f) and hepatocyte-specific Bmal1 knockout (Bmal1hep−/−) C57BL/6J mice underwent a regular feeding regimen. Hepatic CR, lipid content, mitochondrial function, and systemic metabolism were assessed at zeitgeber time (ZT) 0 and ZT12. Relevant molecules were examined to elucidate the metabolic phenotype. Hepatocyte-specific knockout of Bmal1 disrupted the expression of rhythmic genes in the liver. Bmal1hep−/− mice exhibited decreased hepatic TG content at ZT0, primarily due to enhanced lipolysis, reduced lipogenesis, and diminished lipid uptake. The β-oxidation function of liver mitochondria decreased at both ZT0 and ZT12. Our findings on the metabolic profile and associated hepatic lipid metabolism in the absence of Bmal1 in hepatocytes provides new insights into metabolic syndromes from the perspective of liver CR disturbances.
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.
•Exposure to disposable leachates in hot water were linked to a higher element levels.•Disposable paper and plastic can release metals to leachates with high temperature.•The carcinogenic risk of Ni and Be in the disposable leachates is non-negligible.•Health risks of metals from disposable paper and plastic containers cannot be ignored.
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.
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.
Display omitted
•Circadian rhythm in the adrenal gland was more robust than that in the hypothalamus.•Circadian rhythm in organs of the HPA axis was disrupted by PM2.5 exposure.•Expression level of Cyp11b1 was inhibited by ambient PM2.5 exposure at ZT0/24.
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. 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. Alcohol intake significantly increased the levels of alanine aminotransferase (ALT) in plasma, and tumor necrosis factor-alpha (TNF-alpha), 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. 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.
Airborne fine particulate matter (PM2.5) exposure is closely associated with metabolic disturbance, in which brown adipose tissue (BAT) is one of the main contributing organs. However, knowledge of ...the phenotype and mechanism of PM2.5 exposure-impaired BAT is quite limited. In the study, male C57BL/6 mice at three different life phases (young, adult, and middle-aged) were simultaneously exposed to concentrated ambient PM2.5 or filtered air for 8 weeks using a whole-body inhalational exposure system. H&E staining and high-resolution respirometry were used to assess the size of adipocytes and mitochondrial function. Transcriptomics was performed to determine the differentially expressed genes in BAT. Quantitative RT-PCR, immunohistochemistry staining, and immunoblots were performed to verify the transcriptomics and explore the mechanism for BAT mitochondrial dysfunction. Firstly, PM2.5 exposure caused altered BAT morphology and mitochondrial dysfunction in middle-aged but not young or adult mice. Furthermore, PM2.5 exposure increased cellular senescence in BAT of middle-aged mice, accompanied by cell cycle arrest, impaired DNA replication, and inhibited AKT signaling pathway. Moreover, PM2.5 exposure disrupted apoptosis and autophagy homeostasis in BAT of middle-aged mice. Therefore, BAT in middle-aged mice was more vulnerable to PM2.5 exposure, and the cellular senescence-initiated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.
Display omitted
•BAT in middle-aged mice was more vulnerable to PM2.5 exposure.•PM2.5 exposure led to cell cycle arrest and cellular senescence in middle-aged mice.•PM2.5 exposure disrupted apoptosis and autophagy homeostasis in middle-aged 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.
Display omitted
•Gestational exposure to PM2.5 reduces fetal weight and crown-rump length in mice.•Gestational exposure to PM2.5 disturbs mouse placenta development and function.•Gestational exposure to PM2.5 caused dysregulation of autophagy in mouse placenta.
PDF
