Atmospheric ultrafine particles promote vascular calcification via the NF-κB signaling pathway

The Role of Endoplasmic Reticulum Stress in Fine Particulate Matter-Induced Phenotype Switching of Vascular Smooth Muscle Cells

As a major component of air pollution, fine particulate matter (PM2.5) was the second global leading cause of death in 2021. Evidence from humans suggested that PM2.5 was associated with an enhanced coronary calcium score (CAC), and animal studies indicated that PM2.5 induced vascular calcification, while mechanisms remained largely unknown. In this study, PM2.5 enhanced the proliferative potential and migration capacity of human aortic vascular smooth muscle cells (VSMCs), as well as disturbing intracellular Ca2+ homeostasis. Subsequent transcriptomic analysis implicated that PM2.5 could influence genes involved in the IRE1α-mediated unfolded protein responses and reduce the expression of DNAJB9, a co-chaperone that formed a complex with BiP/IRE1α to inhibit the activation of endoplasmic reticulum (ER) stress. Further mechanistic investigations indicated that PM2.5 activated the IRE1α/XBP1 signaling pathway and enhanced the expression of osteogenic phenotype-related hallmarks. In contrast, pretreatment with an ER stress antagonist (4-PBA) could suppress PM2.5-associated calcium dysregulation and osteogenic transformation via alleviation of ER stress. Taken together, this study revealed the role of ER stress in the phenotype switching of VSMCs induced by PM2.5, highlighted the regulation of DNAJB9, provided insights into the mechanisms of air pollution-related vascular calcification, and pointed out molecules for future investigations.

New insight into air pollution-related cardiovascular disease: an adverse outcome pathway framework of PM2.5-associated vascular calcification

Despite the air quality has been generally improved in recent years, ambient fine particulate matter (PM2.5), a major contributor to air pollution, remains one of the major threats to public health. Vascular calcification is a systematic pathology associated with an increased risk of cardiovascular disease. Although the epidemiological evidence has uncovered the association between PM2.5 exposure and vascular calcification, little is known about the underlying mechanisms. The adverse outcome pathway (AOP) concept offers a comprehensive interpretation of all of the findings obtained by toxicological and epidemiological studies. In this review, reactive oxygen species generation was identified as the molecular initiating event (MIE), which targeted subsequent key events (KEs) such as oxidative stress, inflammation, endoplasmic reticulum stress, and autophagy, from the cellular to the tissue/organ level. These KEs eventually led to the adverse outcome, namely increased incidence of vascular calcification and atherosclerosis morbidity. To the best of our knowledge, this is the first AOP framework devoted to PM2.5-associated vascular calcification, which benefits future investigations by identifying current limitations and latent biomarkers.

The synergism of Lactobacillaceae, inulin, polyglucose, and aerobic exercise ameliorates hyperglycemia by modulating the gut microbiota community and the metabolic profiles in db/db mice

This study aimed to assess the impact of Lactobacillaceae (L or H represents a low or high dose), inulin (I), and polydextrose (P) combined with aerobic exercise (A) on the composition of the gut microbiota and metabolic profiles in db/db mice. After a 12-week intervention, LIP, LIPA, and HIPA groups exhibited significant improvements in hyperglycemia, glucose tolerance, insulin resistance, inflammatory response, and short-chain fatty acid (SCFA) and blood lipid levels compared to type 2 diabetes mice (MC). After treatment, the gut microbiota composition shifted favorably in the treatment groups which significantly increased the abundance of beneficial bacteria, such as Bacteroides, Blautia, Akkermansia, and Faecalibaculum, and significantly decreased the abundance of Proteus. Metabolomics analysis showed that compared to the MC group, the contents of 5-hydroxyindoleacetic acid, 3-hydroxysebacic acid, adenosine monophosphate (AMP), xanthine and hypoxanthine were significantly decreased, while 3-ketosphinganine, sphinganine, and sphingosine were significantly increased in the LIP and LIPA groups, respectively. Additionally, LIP and LIPA not only improved sphingolipid metabolism and purine metabolism pathways but also activated AMP-activated protein kinase to promote β-oxidation by increasing the levels of SCFAs. Faecalibaculum, Blautia, Bacteroides, and Akkermansia exhibited positive correlations with sphingosine, 3-ketosphinganine, and sphinganine, and exhibited negative correlations with hypoxanthine, xanthine and AMP. Faecalibaculum, Blautia, Bacteroides, and Akkermansia may have the potential to improve sphingolipid metabolism and purine metabolism pathways. These findings suggest that the synergism of Lactobacillaceae, inulin, polydextrose, and aerobic exercise provides a promising strategy for the prevention and management of type 2 diabetes.

Effect of diesel exhaust particles on RANK/RANKL expression in in vivo and in vitro models of middle ear inflammation

OBJECTIVE

Increasing evidence suggests a link between middle ear inflammation and the development of diesel exhaust particles (DEPs). Chronic middle ear inflammation can lead to bone damage and remodeling. This study aimed to explore the impact of DEPs on the expression of interleukin (IL)-6 and RANKL under conditions of middle ear inflammation.

METHODS

DEPs were collected by burning fuel in a diesel engine at the Gwangju Institute of Science and Technology. Human middle ear epithelial cells were cultured to 70-80% confluence in culture plates and then treated with DEPs at concentrations of 0, 5, 10, 20, 40, and 80 μg/mL for 24 h. Cell viability was assessed manually. B6.SJL mice, aged 9 weeks, were exposed to DEPs at a concentration of 200 μg/m3 for 1 h daily over a period of 28 days. The expression levels of IL-6, tumor necrosis factor α, RANKL, and RANK were evaluated using hematoxylin and eosin staining and western blot analysis of the harvested middle ear samples.

RESULTS

The viability of human middle ear epithelial cells was found to decrease in a dose-dependent manner after 24 h. The mRNA expression level of IL-6 exhibited the most significant increase at the 48-h mark. In contrast, the mRNA expression levels of RANKL and RANK showed a marked increase as early as 6 h post-exposure, with both genes subsequently displaying a time-dependent decrease. Histological analysis revealed that the middle ear mucosa was thicker in the group exposed to DEPs compared to the control group. Additionally, the protein expression levels of IL-6 and RANKL were elevated in the DEP-exposed group relative to the normal control group.

CONCLUSIONS

We confirmed the expression of osteoclast-related proteins in the mouse middle ear. These results imply that air pollutants might affect RANKL/RANK signaling, which is associated with bone remodeling.

The bio-distribution, clearance pathways, and toxicity mechanisms of ambient ultrafine particles

Ambient particles severely threaten human health worldwide. Compared to larger particles, ultrafine particles (UFPs) are highly concentrated in ambient environments, have a larger specific surface area, and are retained for a longer time in the lung. Recent studies have found that they can be transported into various extra-pulmonary organs by crossing the air-blood barrier (ABB). Therefore, to understand the adverse effects of UFPs, it is crucial to thoroughly investigate their bio-distribution and clearance pathways in vivo after inhalation, as well as their toxicological mechanisms. This review highlights emerging evidence on the bio-distribution of UFPs in pulmonary and extra-pulmonary organs. It explores how UFPs penetrate the ABB, the blood-brain barrier (BBB), and the placental barrier (PB) and subsequently undergo clearance by the liver, kidney, or intestine. In addition, the potential underlying toxicological mechanisms of UFPs are summarized, providing fundamental insights into how UFPs induce adverse health effects.

Wildland fire, air pollution and cardiovascular health: is it time to focus on the microvasculature as a risk assessment tool?

Climate change favors weather conditions conducive to wildland fires. The intensity and frequency of forest fires are increasing, and fire seasons are lengthening. Exposure of human populations to smoke emitted by these fires increases, thereby contributing to airborne pollution through the emission of gas and particulate matter (PM). The adverse health outcomes associated with wildland fire exposure represent an important burden on the economies and health systems of societies. Even though cardiovascular diseases (CVDs) are the main of cause of the global burden of diseases attributable to PM exposure, it remains difficult to show reliable associations between exposure to wildland fire smoke and cardiovascular disease risk in population-based studies. Optimal health requires a resilient and adaptable network of small blood vessels, namely, the microvasculature. Often alterations of this microvasculature precede the occurrence of adverse health outcomes, including CVD. Biomarkers of microvascular health could then represent possible markers for the early detection of poor cardiovascular outcomes. This review aims to synthesize the current literature to gauge whether assessing the microvasculature can better estimate the cardiovascular impact of wildland fires.

Co-exposure of PM2.5 and high-fat diet induce lipid metabolism reprogramming and vascular remodeling

Fine particulate matter (PM_2.5) exposure has been proved to increase the cardiovascular disease risk. However, there is a lack of comprehensive knowledge on whether a high-fat diet (HFD) affects PM_2.5-induced cardiovascular disease. The purpose of this study was to investigate the impairment of lipid metabolism and vascular function by PM_2.5 and HFD exposure in ApoE^-/- mice. Oil red O staining indicated that co-treatment of PM_2.5 and HFD resulted in markedly lipid deposition in the mice aorta. Blood biochemical analysis demonstrated that co-exposure of PM_2.5 and HFD could cause dyslipidemia in vivo. Vascular Doppler ultrasound and histopathological analysis found that the functional and structural alterations with fibrosis and calcified remodeling of the vessels were detected after PM_2.5 and HFD exposure. For in-depth study, the genome-wide transcriptional analysis performed in macrophages was further revealed that the endoplasmic reticulum stress, immune system process, regulation of cell proliferation etc. were response to PM_2.5 exposure; while Lipid and atherosclerosis signaling pathways had a critical role in PM_2.5-induced vascular injury. Results from validation experiments manifested that the release of supernatant in PM_2.5- or ox-LDL-treated macrophages could decrease the cell viability and increase the lipid ROS in vascular smooth muscle cells (VSMCs). Moreover, the up-regulations of CCL2, IL-6 and IL-1β in aortic arch of mice were observed after co-exposure with PM_2.5 and HFD. Our data hinted that PM_2.5 could affect the lipid metabolism reprogramming and induce vascular remodeling, accompanied with synergistic effects of HFD.

Rutin ameliorates the promotion effect of fine particulate matter on vascular calcification in calcifying vascular cells and ApoE-/- mice

Atmospheric PM2.5 exposure greatly contributes to the incidence of and mortality from cardiovascular disease (CVD). Owing to the crucial role of vascular calcification in the progression of CVD, it is imperative to elucidate the effects of PM2.5 on vascular calcification to understand the toxic mechanisms of haze-induced CVD. However, the effects of PM2.5 exposure on vascular calcification and the underlying molecular mechanisms are still unclear. In this work, the in vitro and in vivo models were used to illuminate the effects of PM2.5 on vascular calcification. We found that PM2.5 promoted the deposition of hydroxyapatite in calcifying vascular cells. Moreover, hydroxyapatite deposition was significantly enhanced by 3.5 times compared with those in the control group in aortas of ApoE-/- mice after exposure winter PM2.5 (1.5 mg/kg b.w.), accompanied by activation of the OPG/RANKL pathway and inflammatory cytokines' expressions. Moreover, PM2.5-induced reactive oxygen species (ROS) generation was observed. NAC, an ROS inhibitor, observably alleviated the promotion effects of PM2.5 on vascular calcification. Furthermore, rutin effectively prevented vascular calcification by regulating the OPG/RANKL pathway. Our results suggest that PM2.5 play an important role in the occurrence and development of vascular calcification, and that rutin has an antagonistic effect on it.

Inflammation: a putative link between phosphate metabolism and cardiovascular disease

Dietary habits in the western world lead to increasing phosphate intake. Under physiological conditions, extraosseous precipitation of phosphate with calcium is prevented by a mineral buffering system composed of calcification inhibitors and tight control of serum phosphate levels. The coordinated hormonal regulation of serum phosphate involves fibroblast growth factor 23 (FGF23), αKlotho, parathyroid hormone (PTH) and calcitriol. A severe derangement of phosphate homeostasis is observed in patients with chronic kidney disease (CKD), a patient collective with extremely high risk of cardiovascular morbidity and mortality. Higher phosphate levels in serum have been associated with increased risk for cardiovascular disease (CVD) in CKD patients, but also in the general population. The causal connections between phosphate and CVD are currently incompletely understood. An assumed link between phosphate and cardiovascular risk is the development of medial vascular calcification, a process actively promoted and regulated by a complex mechanistic interplay involving activation of pro-inflammatory signalling. Emerging evidence indicates a link between disturbances in phosphate homeostasis and inflammation. The present review focuses on critical interactions of phosphate homeostasis, inflammation, vascular calcification and CVD. Especially, pro-inflammatory responses mediating hyperphosphatemia-related development of vascular calcification as well as FGF23 as a critical factor in the interplay between inflammation and cardiovascular alterations, beyond its phosphaturic effects, are addressed.

The Cell Origin and Role of Osteoclastogenesis and Osteoblastogenesis in Vascular Calcification

Arterial calcification refers to the abnormal deposition of calcium salts in the arterial wall, which results in vessel lumen stenosis and vascular remodeling. Studies increasingly show that arterial calcification is a cell mediated, reversible and active regulated process similar to physiological bone mineralization. The osteoblasts and chondrocytes-like cells are present in large numbers in the calcified lesions, and express osteogenic transcription factor and bone matrix proteins that are known to initiate and promote arterial calcification. In addition, osteoclast-like cells have also been detected in calcified arterial walls wherein they possibly inhibit vascular calcification, similar to the catabolic process of bone mineral resorption. Therefore, tilting the balance between osteoblast-like and osteoclast-like cells to the latter maybe a promising therapeutic strategy against vascular calcification. In this review, we have summarized the current findings on the origin and functions of osteoblast-like and osteoclast-like cells in the development and progression of vascular progression, and explored novel therapeutic possibilities.

Integrating systematic biological and proteomics strategies to explore the pharmacological mechanism of danshen yin modified on atherosclerosis

This research utilized the systematic biological and proteomics strategies to explore the regulatory mechanism of Danshen Yin Modified (DSYM) on atherosclerosis (AS) biological network. The traditional Chinese medicine database and HPLC was used to find the active compounds of DSYM, Pharmmapper database was used to predict potential targets, and OMIM database and GeneCards database were used to collect AS targets. String database was utilized to obtain the other protein of proteomics proteins and the protein-protein interaction (PPI) data of DSYM targets, AS genes, proteomics proteins and other proteins. The Cytoscape 3.7.1 software was utilized to construct and analyse the network. The DAVID database is used to discover the biological processes and signalling pathways that these proteins aggregate. Finally, animal experiments and proteomics analysis were used to further verify the prediction results. The results showed that 140 active compounds, 405 DSYM targets and 590 AS genes were obtained, and 51 differentially expressed proteins were identified in the DSYM-treated ApoE-/- mouse AS model. A total of 4 major networks and a number of their derivative networks were constructed and analysed. The prediction results showed that DSYM can regulate AS-related biological processes and signalling pathways. Animal experiments have also shown that DSYM has a therapeutic effect on ApoE-/-mouse AS model (P < .05). Therefore, this study proposed a new method based on systems biology, proteomics, and experimental pharmacology, and analysed the pharmacological mechanism of DSYM. DSYM may achieve therapeutic effects by regulating AS-related signalling pathways and biological processes found in this research.

LncRNA-SNHG29 inhibits vascular smooth muscle cell calcification by downregulating miR-200b-3p to activate the α-Klotho/FGFR1/FGF23 axis

BACKGROUND

Vascular calcification (VC) is characterized by mineral accumulation on the walls of arteries and veins, which is a pathological process commonly found in elderly individuals and patients with atherosclerosis, hypertension, and diabetes. Emerging evidence suggests that long non-coding RNAs (lncRNAs) play an important role in VC. However, the role of SNHG29 is less clear.

METHODS

The expression of SNHG29, miR-200b-3p, α-Klotho, FGFR1 and FGF23 in vascular smooth muscle cells (VSMCs) was quantified by qRT-PCR and western blot assays. β-GP was used to construct an in vitro calcification model, followed by MTT assay to detect cell viability. Calcification was determined by alizarin red S staining and quantified by calcification assay. ALP activity was investigated by ALP staining. The interactions among SNHG29, miR-200b-3p and α-Klotho were verified by luciferase assay.

RESULTS

In the in vitro calcification model, SNHG29 was downregulated, while miR-200b-3p was upregulated. SNHG29 overexpression and miR-200b-3p knockdown significantly suppressed osteoblast-related factors (RUNX2 and BMP2), accompanied by activation of the α-Klotho/FGFR1/FGF23 axis, further inhibiting the formation of calcified nodules. Moreover, miR-200b-3p overexpression and α-Klotho knockdown reversed the SNHG29 overexpression-induced inhibitory effects on calcified VSMCs.

CONCLUSION

Our study is the first to demonstrate that SNHG29 could inhibit VSMC calcification by downregulating miR-200b-3p to activate the α-Klotho/FGFR1/FGF23 axis, suggesting SNHG29 as a novel therapeutic target for VC-associated diseases.

Immunologic and Non-Immunologic Mechanisms Leading to Airway Remodeling in Asthma

Asthma increases worldwide without any definite reason and patient numbers double every 10 years. Drugs used for asthma therapy relax the muscles and reduce inflammation, but none of them inhibited airway wall remodeling in clinical studies. Airway wall remodeling can either be induced through pro-inflammatory cytokines released by immune cells, or direct binding of IgE to smooth muscle cells, or non-immunological stimuli. Increasing evidence suggests that airway wall remodeling is initiated early in life by epigenetic events that lead to cell type specific pathologies, and modulate the interaction between epithelial and sub-epithelial cells. Animal models are only available for remodeling in allergic asthma, but none for non-allergic asthma. In human asthma, the mechanisms leading to airway wall remodeling are not well understood. In order to improve the understanding of this asthma pathology, the definition of “remodeling” needs to be better specified as it summarizes a wide range of tissue structural changes. Second, it needs to be assessed if specific remodeling patterns occur in specific asthma pheno- or endo-types. Third, the interaction of the immune cells with tissue forming cells needs to be assessed in both directions; e.g., do immune cells always stimulate tissue cells or are inflamed tissue cells calling immune cells to the rescue? This review aims to provide an overview on immunologic and non-immunologic mechanisms controlling airway wall remodeling in asthma.

O-GlcNAcylation as a Therapeutic Target for Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia and the number of elderly patients suffering from AD has been steadily increasing. Despite worldwide efforts to cope with this disease, little progress has been achieved with regard to identification of effective therapeutics. Thus, active research focusing on identification of new therapeutic targets of AD is ongoing. Among the new targets, post-translational modifications which modify the properties of mature proteins have gained attention. O-GlcNAcylation, a type of PTM that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to a protein, is being sought as a new target to treat AD pathologies. O-GlcNAcylation has been known to modify the two important components of AD pathological hallmarks, amyloid precursor protein, and tau protein. In addition, elevating O-GlcNAcylation levels in AD animal models has been shown to be effective in alleviating AD-associated pathology. Although studies investigating the precise mechanism of reversal of AD pathologies by targeting O-GlcNAcylation are not yet complete, it is clearly important to examine O-GlcNAcylation regulation as a target of AD therapeutics. This review highlights the mechanisms of O-GlcNAcylation and its role as a potential therapeutic target under physiological and pathological AD conditions.

Ma Xing Shi Gan Decoction Attenuates PM2.5 Induced Lung Injury via Inhibiting HMGB1/TLR4/NFκB Signal Pathway in Rat

Ma Xing Shi Gan Decoction (MXD), a classical traditional Chinese medicine prescription, is widely used for the treatment of upper respiratory tract infection. However, the effect of MXD against particulate matters with diameter of less than 2.5 μm (PM2.5) induced lung injury remains to be elucidated. In this study, rats were stimulated with PM2.5 to induce lung injury. MXD was given orally once daily for five days. Lung tissues were harvested to assess pathological changes and edema. Myeloperoxidase (MPO) activity and malonaldehyde (MDA) content in lung were determined to evaluate the degree of injury. To assess the barrier disruption, the bronchoalveolar lavage fluid (BALF) was collected to determine the total protein content and count the number of neutrophils and macrophages. For evaluating the activation of macrophage in lung tissue, CD68 was detected using immunohistochemistry (IHC). The levels of inflammatory factors including tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6) in BALF and serum were measured. In vitro, a PM2.5-activated RAW 264.7 macrophages inflammatory model was introduced. To evaluate the protective effect of MXD-medicated serum, the cell viability and the release of inflammatory factors were measured. The effects of MXD on the High mobility group box-1/Toll-like receptor 4/Nuclear factor-kappa B (HMGB1/TLR4/NFκB) pathway in lung tissue and RAW 264.7 cells were assessed by Western blot. For further confirming the protective effect of MXD was mediated by inhibiting the HMGB1/TLR4/NFκB pathway, RAW 264.7 cells were incubated with MXD-medicated serum alone or MXD-medicated serum plus recombinant HMGB1 (rHMGB1). MXD significantly ameliorated the lung injury in rats, as evidenced by decreases in the pathological score, lung edema, MPO activity, MDA content, CD68 positive macrophages number, disruption of alveolar capillary barrier and the levels of inflammatory factors. In vitro, MXD-medicated serum increased cell viability and inhibited the release of inflammatory cytokines. Furthermore, MXD treatment was found to inhibit HMGB1/TLR4/NFκB signal pathway both in vivo and in vitro. Moreover, the protection of MXD could be reversed by rHMGB1 in RAW 264.7. Taken together, these results suggest MXD protects rats from PM2.5 induced acute lung injury, possibly through the modulation of HMGB1/TLR4/NFκB pathway and inflammatory responses.

Diesel Exhaust Induces Mitochondrial Dysfunction, Hyperlipidemia, and Liver Steatosis

OBJECTIVE

Air pollution is associated with increased cardiovascular morbidity and mortality, as well as dyslipidemia and metabolic syndrome. Our goal was to dissect the mechanisms involved. Approach and Results: We assessed the effects of exposure to air pollution on lipid metabolism in mice through assessment of plasma lipids and lipoproteins, oxidized fatty acids 9-HODE (9-hydroxyoctadecadienoic) and 13-HODE (13-hydroxyoctadecadienoic), lipid, and carbohydrate metabolism. Findings were corroborated, and mechanisms were further assessed in HepG2 hepatocytes in culture. ApoE knockout mice exposed to inhaled diesel exhaust (DE, 6 h/d, 5 days/wk for 16 weeks) exhibited elevated plasma cholesterol and triglyceride levels, increased hepatic triglyceride content, and higher hepatic levels of 9-HODE and 13-HODE, as compared to control mice exposed to filtered air. A direct effect of DE exposure on hepatocytes was demonstrated by treatment of HepG2 cells with a methanol extract of DE particles followed by loading with oleic acid. As observed in vivo, this led to increased triglyceride content and significant downregulation of ACAD9 mRNA expression. Treatment of HepG2 cells with DE particles and oleic acid did not alter de novo lipogenesis but inhibited total, mitochondrial, and ATP-linked oxygen consumption rate, indicative of mitochondrial dysfunction. Treatment of isolated mitochondria, prepared from mouse liver, with DE particles and oleic acid also inhibited mitochondrial complex activity and β-oxidation.

CONCLUSIONS

DE exposure leads to dyslipidemia and liver steatosis in ApoE knockout mice, likely due to mitochondrial dysfunction and decreased lipid catabolism.

Thyroxine Affects Lipopolysaccharide-Induced Macrophage Differentiation and Myocardial Cell Apoptosis via the NF-κB p65 Pathway Both In Vitro and In Vivo

Background

Numerous studies have demonstrated that the inflammatory response is involved in the progression of lipopolysaccharide- (LPS-) induced myocardial cell apoptosis. Accumulating evidence has shown that thyroxine participates in diseases by downregulating the inflammatory response. This study aimed at investigating whether thyroxine alleviates LPS-induced myocardial cell apoptosis.

Methods

Bone marrow-derived macrophages (Mø) were treated with LPS and thyroxine, and Mø differentiation and Mø-related cytokine expression were measured. The effect of Mø differentiation on mouse cardiomyocyte (MCM) apoptosis was also detected in vitro. In addition, C57BL/6 mice underwent thyroidectomy and were treated with LPS 35 days later; subsequently, Mø differentiation and myocardial cell apoptosis in hearts were analyzed. To determine whether the nuclear factor-kappa B (NF-κB) p65 pathway mediates the effect of thyroxine on Mø differentiation and myocardial cell apoptosis, the specific NF-κB p65 pathway inhibitor JSH-23 was administered to mice that underwent a thyroidectomy.

Results

Levothyroxine treatment significantly reduced the activation of the NF-κB p65 pathway, decreased M1 macrophage (Mø1) differentiation and Mø1-related cytokine mRNA levels in LPS-treated Mø, and increased M2 macrophage (Mø2) differentiation and Mø2-related cytokine mRNA expression. The protective effects of levothyroxine on MCM apoptosis mediated by LPS-treated Mø were alleviated by JSH-23. In mice, thyroidectomy aggravated LPS-induced cardiac injury and cardiac dysfunction, further promoted NF-κB p65 activation, and increased cardiac Mø1 expression and myocardial cell apoptosis but decreased cardiac Mø2 expression. JSH-23 treatment significantly ameliorated the thyroidectomy-induced increases in myocardial cell apoptosis and Mø differentiation.

Conclusions

Thyroxine alleviated the Mø1/Mø2 imbalance, reduced the inflammatory response, decreased myocardial cell apoptosis, and protected against cardiac injury and cardiac dysfunction in LPS-treated mice. Thyroxine may be a novel therapeutic strategy to prevent and treat LPS-induced cardiac injury.

The toll like receptor 4-myeloid differentiation factor 88 pathway is essential for particulate matter-induced activation of CD4-positive cells

Asian sand dust (ASD), a type of particulate matter (PM) found in Asia, can be transported to East Asia. We recently found that acute splenic inflammation is induced by ASD in mouse models. In this study, we examined the effect of sub-chronic ASD exposure on mouse immune cells. Mice were intratracheally administered ASD once every 2 weeks for 8 weeks and killed 24 hours after the final administration. Wild-type (WT) mice showed increased cell viability after ASD administration. In contrast, ASD administration induced splenocyte activation in toll-like receptor (TLR)2^-/- , but not TLR4^-/- mice. Furthermore, concanavalin A-induced interleukin-2 production increased after ASD administration in WT and TLR2^-/- mice, but not in TLR4^-/- or myeloid differentiation factor (MyD)88^-/- mice. Immunoblotting demonstrated that nuclear factor κB (NF-κB) was activated in WT mice, but not in TLR4^-/- or MyD88^-/- mice. The NF-κB-dependent gene products CDK2 and intercellular cell adhesion molecule-1 were upregulated upon ASD administration in WT mice, but not in TLR4^-/- or MyD88^-/- mice. Furthermore, the particles themselves, rather than particle constituents, activated NF-κB in CD4-positive cells through the TLR4 or MyD88 pathway. Taken together, these results indicate that particle-induced splenic inflammation occurs via TLR4-MyD88 signaling.

Selenoprotein S inhibits inflammation-induced vascular smooth muscle cell calcification

Vascular calcification is a prominent feature of many diseases including atherosclerotic cardiovascular disease (CVD), leading to high morbidity and mortality rates. A significant association of selenoprotein S (SelS) gene polymorphism with atherosclerotic CVD has been reported in epidemiologic studies, but the underlying mechanism is far from clear. To investigate the role of SelS in inflammation-induced vascular calcification, osteoblastic differentiation and calcification of vascular smooth muscle cells (VSMCs) induced by lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α were compared between the cells with and without SelS knockdown. LPS or TNF-α induced osteoblastic differentiation and calcification of VSMCs, as showed by the increases of runt-related transcription factor 2 (Runx2) protein levels, Runx2 and type I collagen mRNA levels, alkaline phosphatase activity, and calcium deposition content. These changes were aggravated when SelS was knocked down by small interfering RNA. Moreover, LPS activated both classical and alternative pathways of nuclear factor-κB (NF-κB) signaling in calcifying VSMCs, which were further enhanced under SelS knockdown condition. SelS knockdown also exacerbated LPS-induced increases of proinflammatory cytokines TNF-α and interleukin-6 expression, as well as increases of endoplasmic reticulum (ER) stress markers glucose-regulated protein 78 and inositol-requiring enzyme 1α expression in calcifying VSMCs. In conclusion, the present study suggested that SelS might inhibit inflammation-induced VSMC calcification probably by suppressing activation of NF-κB signaling pathways and ER stress. Our findings provide new understanding of the role of SelS in vascular calcification, which will be potentially beneficial to the prevention of atherosclerotic CVD.

Transcriptional profiling of human bronchial epithelial cell BEAS-2B exposed to diesel and biomass ultrafine particles

BACKGROUND

Emissions from diesel vehicles and biomass burning are the principal sources of primary ultrafine particles (UFP). The exposure to UFP has been associated to cardiovascular and pulmonary diseases, including lung cancer. Although many aspects of the toxicology of ambient particulate matter (PM) have been unraveled, the molecular mechanisms activated in human cells by the exposure to UFP are still poorly understood. Here, we present an RNA-seq time-course experiment (five time point after single dose exposure) used to investigate the differential and temporal changes induced in the gene expression of human bronchial epithelial cells (BEAS-2B) by the exposure to UFP generated from diesel and biomass combustion. A combination of different bioinformatics tools (EdgeR, next-maSigPro and reactome FI app-Cytoscape and prioritization strategies) facilitated the analyses the temporal transcriptional pattern, functional gene set enrichment and gene networks related to cellular response to UFP particles.

RESULTS

The bioinformatics analysis of transcriptional data reveals that the two different UFP induce, since the earliest time points, different transcriptional dynamics resulting in the activation of specific genes. The functional enrichment of differentially expressed genes indicates that the exposure to diesel UFP induces the activation of genes involved in TNFα signaling via NF-kB and inflammatory response, and hypoxia. Conversely, the exposure to ultrafine particles from biomass determines less distinct modifications of the gene expression profiles. Diesel UFP exposure induces the secretion of biomarkers associated to inflammation (CCXL2, EPGN, GREM1, IL1A, IL1B, IL6, IL24, EREG, VEGF) and transcription factors (as NFE2L2, MAFF, HES1, FOSL1, TGIF1) relevant for cardiovascular and lung disease. By means of network reconstruction, four genes (STAT3, HIF1a, NFKB1, KRAS) have emerged as major regulators of transcriptional response of bronchial epithelial cells exposed to diesel exhaust.

CONCLUSIONS

Overall, this work highlights modifications of the transcriptional landscape in human bronchial cells exposed to UFP and sheds new lights on possible mechanisms by means of which UFP acts as a carcinogen and harmful factor for human health.

A critical review of assays for hazardous components of air pollution

Increased mortality and diverse morbidities are globally associated with exposure to ambient air pollution (AAP), cigarette smoke (CS), and household air pollution (HAP). The AAP-CS-HAP aerosols present heterogeneous particulate matter (PM) of diverse chemical and physical characteristics. Some epidemiological models have assumed the same health hazards by PM weight for AAP, CS, and HAP regardless of the composition. While others have recognized that biological activities and toxicity will vary with components, we focus particularly on oxidation because of its major role in assay outcomes. Our review of PM assays considers misinterpretations of some chemical measures used for oxidative activity. Overall, there is low consistency across chemical and cell-based assays for oxidative and inflammatory activity. We also note gaps in understanding how much airborne PM of various sizes enter cells and organs. For CS, the body burden per cigarette may be much below current assumptions. Synergies shown for health hazards of AAP and CS suggest crosstalk in detoxification pathways mediated by AHR, NF-κB, and Nrf2. These complex genomic and biochemical interactions frustrate resolution of the toxicity of specific AAP components. We propose further strategies based on targeted gene expression based on cell-type differences.

N-acetyl-l-cysteine ameliorates the PM2.5-induced oxidative stress by regulating SIRT-1 in rats

Silent information regulator 1 (SIRT1), a class III histone deacetylase, plays a major role in combating cellular oxidative stress injury. However, the role of SIRT1 in oxidative stress induced by particulate matter remains unclear. A total of 32 healthy male Sprague-Dawley rats were divided into PM_2.5, PM_2.5+NAC, filtered air (control), and filtered air+NAC (NAC control) groups. The expressions of MnSOD, SIRT1, and FOXO3a were examined at both transcriptional and protein levels. The expression levels of MnSOD, SIRT1, and FOXO3a reduced significantly (P<0.05) in the PM_2.5 group as compared to the control group. However, their expression levels were increased after NAC intervention. These results suggested that SIRT1 exerted a protective effect against PM_2.5-induced respiratory oxidative damage by regulating the expression of FOXO3a. NAC can activate SIRT1 and exert an anti-oxidative role in PM_2.5-induced oxidative injury.

Lipopolysaccharide attached to urban particulate matter 10 suppresses immune responses in splenocytes while particulate matter itself activates NF-κB

We previously reported that Asian sand dust (ASD), which contains particulate matter (PM) less than 10 μm in diameter (PM10), induced subacute inflammation in splenocytes. However, it was unclear whether the PM itself or compounds attached to its surface induced the inflammation. Here we characterized the role of organic substances adsorbed onto the PM10 surface in triggering inflammation by comparing the effect on splenocyte activation of PM10 from urban areas (urPM10), which is rich in lipopolysaccharide (LPS) as compared to ASD, with that of heated PM10 (H-PM). BALB/c mice were intratracheally administered urPM10 or H-PM with or without LPS (1 ng and 10 ng) four times at 2-week intervals, and splenocytes were prepared at 24 h after the final administration to assay the immune responses. urPM10 suppressed splenocyte activation, while H-PM activated splenocytes and LPS neutralization by polymyxin B rescued urPM10-induced immunosuppression. Co-administration of LPS with H-PM clearly suppressed mitogen-induced immune responses in the spleen. Consistent with these results, H-PM induced the phosphorylation of nuclear factor κB (NF-κB) p65 and I kappa B kinase (IKK), which was inhibited by co-administration of LPS. In mice deficient in the LPS signal transducer MyD88, splenocyte activation after LPS or H-PM treatment in vivo was comparable to that in the control. Altogether, our results indicate that PM10 itself could activate NF-κB through the MyD88 pathway, which was modulated by the amount of LPS attached.

Metabolomics in diabetic complications

With a global prevalence of 9%, diabetes is the direct cause of millions of deaths each year and is quickly becoming a health crisis. Major long-term complications of diabetes arise from persistent oxidative stress and dysfunction in multiple metabolic pathways. The most serious complications involve vascular damage and include cardiovascular disease as well as microvascular disorders such as nephropathy, neuropathy, and retinopathy. Current clinical analyses like glycated hemoglobin and plasma glucose measurements hold some value as prognostic indicators of the severity of complications, but investigations into the underlying pathophysiology are still lacking. Advancements in biotechnology hold the key to uncovering new pathways and establishing therapeutic targets. Metabolomics, the study of small endogenous molecules, is a powerful toolset for studying pathophysiological processes and has been used to elucidate metabolic signatures of diabetes in various biological systems. Current challenges in the field involve correlating these biomarkers to specific complications to provide a better prediction of future risk and disease progression. This review will highlight the progress that has been made in the field of metabolomics including technological advancements, the identification of potential biomarkers, and metabolic pathways relevant to macro- and microvascular diabetic complications.

Inflammatory cell signaling following exposures to particulate matter and ozone

BACKGROUND

Particulate matter (PM) and ozone (O3) are two major ambient air pollutants. Epidemiological and toxicological studies have demonstrated exposure to these pollutants is associated with a variety of adverse health effects, including cardiovascular and respiratory disease, in which inflammation is believed to be a common and essential factor.

SCOPE OF REVIEW

This review mainly focuses on major inflammatory cell signaling pathways triggered by exposure to PM and O3. The receptors covered in this review include the EGF receptor, toll like receptor, and NOD-like receptor. Intracellular signaling protein kinases depicted in this review are phosphatidylinositol 3-kinase and mitogen-activated protein kinases. Activation of antioxidant and inflammatory transcription factors such as NrF2 and NFκB induced by PM and O3 is also discussed.

MAJOR CONCLUSIONS

Exposure to PM or O3 can activate cellular signaling networks including membrane receptors, intracellular kinases and phosphatases, and transcription factors that regulate inflammatory responses. While PM-induced cell signaling is associated with resultant ROS, O3-induced cell signaling implicates phosphates. Notably, the cellular signaling induced by PM and O3 exposure varies with cell type and physiochemical properties of these pollutants.

GENERAL SIGNIFICANCE

Cellular signaling plays a critical role in the regulation of inflammatory pathogenesis. Elucidation of cellular signaling pathways initiated by PM or O3 cannot only help to uncover the mechanisms of air pollutant toxicity but also provide clues for development of interventional measures against air pollution-induced disorders. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.

Microvascular Dysfunction and Cognitive Impairment

The impact of vascular risk factors on cognitive function has garnered much interest in recent years. The appropriate distribution of oxygen, glucose, and other nutrients by the cerebral vasculature is critical for proper cognitive performance. The cerebral microvasculature is a key site of vascular resistance and a preferential target for small vessel disease. While deleterious effects of vascular risk factors on microvascular function are known, the contribution of this dysfunction to cognitive deficits is less clear. In this review, we summarize current evidence for microvascular dysfunction in brain. We highlight effects of select vascular risk factors (hypertension, diabetes, and hyperhomocysteinemia) on the pial and parenchymal circulation. Lastly, we discuss potential links between microvascular disease and cognitive function, highlighting current gaps in our understanding.

Immunotoxicological impact of occupational and environmental nanoparticles exposure: The influence of physical, chemical, and combined characteristics of the particles

While nanotechnology is growing exponentially, the knowledge of the impact of nanoparticles (NPs) on public health and the environment is limited so far. Current nanomaterial research is focused on the applications of nanotechnology, whereas there is little information on exposure assessment and risk characterization associated with NPs. Therefore, it is essential that the factors influencing NPs associated hazards be studied. This review seeks to survey and evaluate the current literature in order to better understand the impact of both airborne and engineered NPs exposure, the mechanisms at the cellular level, and the factors influencing their immunotoxicity. In fact, NPs do have immunotoxicological significance, as immune cells in the bloodstream and tissues do act to eliminate or interact with NPs.Proper characterization of the NPs as well as understanding the processes occurring on the NPs surface when in contact with biological systems is crucial to predict or exclude toxicological effects.

Evaluation of in vitro cytoxicity and genotoxicity of size-fractionated air particles sampled during road tunnel construction

In tunnel construction, workers exposed to dust from blasting, gases, diesel exhausts, and oil mist have shown higher risk for pulmonary diseases. A clear mechanism to explain how these pollutants determine diseases is lacking, and alveolar epithelium's capacity to ingest inhaled fine particles is not well characterized. The objective of this study was to assess the genotoxic effect exerted by fine particles collected in seven tunnels using the cytokinesis-block micronuclei test in an in vitro model on type II lung epithelium A549 cells. For each tunnel, five fractions with different aerodynamic diameters of particulate matter were collected with a multistage cascade sampler. The human epithelial cell line A549 was exposed to 0.2 m(3)/mL equivalent of particulate for 24 h before testing. The cytotoxic effects of particulate matter on A549 cells were also evaluated in two different viability tests. In order to evaluate the cells' ability to take up fine particles, imaging with transmission electron microscopy of cells after exposure to particulate matter was performed. Particle endocytosis after 24 h exposure was observed as intracellular aggregates of membrane-bound particles. This morphologic evidence did not correspond to an increase in genotoxicity detected by the micronucleus test.

Ambient ultrafine particles reduce endothelial nitric oxide production via S-glutathionylation of eNOS

Exposure to airborne particulate pollutants is intimately linked to vascular oxidative stress and inflammatory responses with clinical relevance to atherosclerosis. Particulate matter (PM) has been reported to induce endothelial dysfunction and atherosclerosis. Here, we tested whether ambient ultrafine particles (UFP, diameter <200 nm) modulate eNOS activity in terms of nitric oxide (NO) production via protein S-glutathionylation. Treatment of human aortic endothelial cells (HAEC) with UFP significantly reduced NO production. UFP-mediated reduction in NO production was restored in the presence of JNK inhibitor (SP600125), NADPH oxidase inhibitor (Apocynin), anti-oxidant (N-acetyl cysteine), and superoxide dismutase mimetics (Tempol and MnTMPyP). UFP exposure increased the GSSG/GSH ratio and eNOS S-glutathionylation, whereas over-expression of Glutaredoxin-1 (to inhibit S-glutathionylation) restored UFP-mediated reduction in NO production by nearly 80%. Thus, our findings suggest that eNOS S-glutathionylation is a potential mechanism underlying ambient UFP-induced reduction of NO production.

Air particulate matter and cardiovascular disease: a narrative review

Consistent evidences from both epidemiological and experimental studies have demonstrated that short- and long-term exposure to particulate matter (PM), in particular to the finest particles (i.e. airborne PM with aerodynamic diameter less than 2.5 μm, PM2.5), is associated with cardiovascular morbidity and mortality. PM concentration has been linked with several clinical manifestations of cardiovascular diseases (CVD), including myocardial infarction, stroke, heart failure, arrhythmias, and venous thromboembolism. Noteworthy, some groups of subjects, like elderly, diabetics, or those with known coronary artery disease, appear specifically susceptible to the harmful effects triggered by PM exposure. Although the PM-related risk for a single individual appears relatively low, the PM-related population attributable risk is impressive. Recent studies indicate that the PM-CVD relationship is likely more complex than a mere quantitative association between overall PM concentration and disease risk. Indeed, the biological effects of PM may vary in function of both the aerodynamic diameter and the chemical composition. Moreover, it has been shown that the influence of air pollution on health is not limited to PM. Indeed, other gaseous pollutants may play an independent role in CVD, suggesting the need to develop multi-pollutant preventive approaches. Causality has been recently strongly supported by observations showing reduced CVD mortality after coordinated community policies resulting in lowering PM exposure at population level. An in-depth knowledge on the heterogeneous sources, chemical compounds, and biological effects of PM may help to propose more accurate and clinically effective recommendations for this important and modifiable factor contributing to CVD burden.

Ambient ultrafine particles alter lipid metabolism and HDL anti-oxidant capacity in LDLR-null mice

Exposure to ambient particulate matter (PM) is a risk factor for cardiovascular diseases. The redox-active ultrafine particles (UFPs) promote vascular oxidative stress and inflammatory responses. We hypothesized that UFPs modulated lipid metabolism and anti-oxidant capacity of high density lipoprotein (HDL) with an implication in atherosclerotic lesion size. Fat-fed low density lipoprotein receptor-null (LDLR⁻/⁻ mice were exposed to filtered air (FA) or UFPs for 10 weeks with or without administering an apolipoprotein A-I mimetic peptide made of D-amino acids, D-4F. LDLR⁻/⁻ mice exposed to UFPs developed a reduced plasma HDL level (P < 0.01), paraoxonase activity (P < 0.01), and HDL anti-oxidant capacity (P < 0.05); but increased LDL oxidation, free oxidized fatty acids, triglycerides, serum amyloid A (P < 0.05), and tumor necrosis factor α (P < 0.05), accompanied by a 62% increase in the atherosclerotic lesion ratio of the en face aortic staining and a 220% increase in the cross-sectional lesion area of the aortic sinus (P < 0.001). D-4F administration significantly attenuated these changes. UFP exposure promoted pro-atherogenic lipid metabolism and reduced HDL anti-oxidant capacity in fat-fed LDLR⁻/⁻ mice, associated with a greater atherosclerotic lesion size compared with FA-exposed animals. D-4F attenuated UFP-mediated pro-atherogenic effects, suggesting the role of lipid oxidation underlying UFP-mediated atherosclerosis.