Zinc-associated phospholipid metabolic alterations and their impacts on ALT levels in workers.

Zinc (Zn) is an essential trace element that is required for various biological functions, but excessive exposure to Zn is associated with many disorders and even diseases. However, the health effects and underlying mechanisms of long-term and high concentration exposure of Zn remain to be unclear. In the present study, we investigated the association between occupational exposure to Zn and liver function indicators (like alanine aminotransferase (ALT)) in workers. We found a positive association between Zn exposure and ALT level in workers. Workers having higher blood Zn (7735.65 (1159.15) µg/L) shows a 30.4 % increase in ALT level compared to those with lower blood Zn (5969.30 (989.26) µg/L). Furthermore, we explored the effects of phospholipids (PLs) and their metabolism on ALT level and discovered that Zn exposure in workers was associated with changes in PL levels and metabolism, which had further effects on increased ALT levels in workers. The study provides insights into the relationship between occupational Zn exposure and liver function, highlights the risk of long-term exposure to high concentrations of Zn, and paves the way for understanding the underlying mechanisms of Zn exposure on human health.

Lead activates neutrophil degranulation to induce early myocardial injury in mice.

Lead (Pb) is a pervasive toxic metal contaminant associated with a high risk of myocardial injury. However, the precise mechanism underlying Pb-induced myocardial injury has yet to be fully elucidated. In this study, a murine model of Pb exposure (0, 1, 5, and 10 mg/kg) was employed to investigate the involvement of neutrophil degranulation in the induction of myocardial injury. Notably, serum levels of cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB) increased significantly in Pb-exposed mice, whereas cTnI levels in cardiomyocytes decreased, suggesting that Pb exposure may cause early myocardial injury. Moreover, Pb exposure was found to promote neutrophil degranulation, as evidenced by elevated myeloperoxidase (MPO) and neutrophil elastase (NE) concentrations in both the serum of Pb-exposed workers and Pb-exposed mice, as well as the extracellular supernatant of neutrophils following exposure. However, we found that serum level of cTnI enhanced by Pb exposure is associated with increased NE levels in the serum, but not with MPO levels. Upon treatment with NE inhibitor (sivelestat), the serum level of cTnI markedly reduced in Pb-exposed mice, we found that early myocardial injury is associated with NE levels in the serum. At the molecular level, western blotting analysis revealed an upregulation of ERK1/2 expression in vitro following Pb exposure, suggesting that the activation of the ERK1/2 signaling pathway may underlie the participation of neutrophil degranulation in Pb-induced myocardial injury. In summary, our findings demonstrate that Pb exposure can initiate early myocardial injury by promoting the neutrophil degranulation process, thereby highlighting the potential role of this process in the pathogenesis of Pb-associated myocardial injury.

Apelin Prevents and Alleviates Crystalline Silica-induced Pulmonary Fibrosis via Inhibiting Transforming Growth Factor Beta 1-triggered Fibroblast Activation.

Silicosis is a common and ultimately fatal occupational disease, yet the limited therapeutic option remains the major clinical challenge. Apelin, an endogenous ligand of the G-protein-coupled receptor (APJ), is abundantly expressed in diverse organs. The apelin-APJ axis helps to control pathological and physiological processes in lung. The role of apelin in the pathological process and its possible therapeutic effects on silicosis have not been elucidated. In this study, we found that lung expression and circulating levels of apelin were markedly decreased in silicosis patients and silica-induced fibrotic mice and associated with the severity. Furthermore, in vivo data demonstrated that pre-treatment from day 3 and post-treatment from day 15 with apelin could both alleviate silica-induced pulmonary fibrosis in mice. Besides, apelin inhibited pulmonary fibroblast activation via transforming growth factor beta 1 (TGF-ß1) signaling. Our study suggested that apelin could prevent and reverse silica-induced pulmonary fibrosis by inhibiting the fibroblast activation through TGF-ß1 signaling pathway, thus providing a new potential therapeutic strategy for silicosis and other pulmonary fibrosis.

Anti-inflammatory protein TSG-6 secreted by BMSCs attenuates silica-induced acute pulmonary inflammation by inhibiting NLRP3 inflammasome signaling in macrophages.

Silicosis is a severe occupational lung disease caused by inhalation of silica particles. Unfortunately, there are currently limited treatment options available for silicosis. Recent advances have indicated that bone marrow mesenchymal stem cells (BMSCs) have a therapeutic effect on silicosis, but their efficacy and underlying mechanisms remain largely unknown. In this study, we focused on the early phase of silica-induced lung injury to investigate the therapeutic effect of BMSCs. Our findings demonstrated that BMSCs attenuated silica-induced acute pulmonary inflammation by inhibiting NLRP3 inflammasome pathways in lung macrophages. To further understand the mechanisms involved, we utilized RNA sequencing to analyze the transcriptomes of BMSCs co-cultured with silica-stimulated bone marrow-derived macrophages (BMDMs). The results clued tumor necrosis factor-stimulated gene 6 (TSG-6) might be a potentially key paracrine secretion factor released from BMSCs, which exerts a protective effect. Furthermore, the anti-inflammatory and inflammasome pathway inhibition effects of BMSCs were attenuated when TSG-6 expression was silenced, both in vivo and in vitro. Additionally, treatment with exogenous recombinant mouse TSG-6 (rmTSG-6) demonstrated similar effects to BMSCs in attenuating silica-induced inflammation. Overall, our findings suggested that BMSCs can regulate the activation of inflammasome in macrophages by secreting TSG-6, thereby protecting against silica-induced acute pulmonary inflammation both in vivo and in vitro.

Identification of lead-binding proteins as carriers and potential molecular targets associated with systolic blood pressure.

Lead (Pb) exposure is well recognized as a significant environmental factor associated with the high incidence of cardiovascular diseases. However, the carriers and molecular targets of Pb in human blood remain to be understood, especially for a real Pb exposure scenario. In this study, a total of 350 blood samples were collected from the smelting workers and systematically analyzed using metallomics and metalloproteomics approaches. The results showed that the majority of Pb (∼99.4%) could be presented in the blood cells. Pb in the cytoplasm of blood cells accounted for approximately 83.1% of the total blood Pb, with nearly half of Pb being bound to proteins. Pb-binding proteins in the blood of workers were identified as hemoglobin, catalase, haptoglobin, δ-aminolevulinic acid dehydratase, and peroxiredoxin-2. Multiple linear regression analysis demonstrated that higher levels of Pb bound to proteins (Mix-bound Pb and Protein-bound Pb) were positively associated with higher systolic blood pressure (p < 0.05). However, the association between blood lead level, Pb levels in the blood cells and systolic blood pressure was not observed (p > 0.05). This study suggested that Pb bound to proteins could be a suitable biomarker for indicating the potential risk of occupational hypertension.

Sensitive determination of metalloprotein in salt-rich matrices by size exclusion chromatography coupled with inductively coupled plasma-mass spectrometry.

Metalloproteins play crucial and distinct roles in a variety of biological processes that rely heavily on the metal ions and various proteins. However, there is still a lack of method for rapid analysis of metalloproteins in complex samples, especially in salt-rich matrices. In this study, a sensitive method for separation and determination of metalloproteins in salt-rich matrices was developed based on the size exclusion chromatography coupled with inductively coupled plasma-mass spectrometry (SEC-ICP-MS), combining with the high matrix introduction (HMI) mode, which is quite essential for biological system. The separation conditions of the SEC-ICP-MS system were optimized by using four iodine labeled proteins with different molecular weights, including bovine serum albumin (BSA, 66.0 kDa), ovalbumin (OVA, 44.0 kDa), carbonic anhydrase (CA, 29.0 kDa) and ribonuclease A (RA, 13.7 kDa). After optimization, four iodine labeled proteins and iodine ions were successfully separated within 30 min by using 10 mmol/L HEPES and 40 mmol/L Na2SO4 (pH=7.0) as mobile phase and a linear relationship between log molecular weight and retention time was established. The relative standard deviations (RSDs, n = 5) of the retention time and peak areas for the four iodine labeled proteins were in the range of 0.2-0.9% and 3.3-7.7%, respectively, suggesting good precision and repeatability. Then the proposed method was successfully applied to the rapid separation and detection of lead-binding proteins in real biological tissue samples.

Characterization of the mercury-binding proteins in tuna and salmon sashimi: Implications for health risk of mercury in food.

Fish consumption is one of the major ways through which humans receive exposure to mercury (Hg). The existing forms of Hg in food, particularly Hg bound to proteins, may affect the absorption of Hg by humans and subsequently its potentially toxic effects. However, the knowledge regarding Hg-binding proteins in edible fish muscle is scarce. In the present study, salmon and tuna fish muscles, collected from seven different regions and countries, were analyzed using metallomics- and proteomics-based techniques. The concentration of Hg in sashimi samples ranged from 4.4 to 317.4 ng/g. Size exclusion chromatography (SEC) coupled with inductively coupled plasma mass spectrometer (ICP-MS) showed that beta-actin was a novel Hg-binding protein from the fish muscles, and this protein could also bind bismuth (Bi), silver (Ag), and copper (Cu). Hg bound to beta-actin accounted for approximately 30.2-37.6% of the total Hg in the tuna muscles and was significantly correlated to total Hg in the fish muscles (r = 0.98, p < 0.01) and in the fraction of soluble proteins (r = 0.94, p < 0.01). These findings suggest that proteins act as the main Hg accumulation sites in edible fish; thus, increasing human exposure to Hg following gastrointestinal digestion.

Identification and characterization of Gd-binding proteins in NIH-3T3 cells.

Gadolinium-based contrast agents (GBCAs), frequently applied in clinical diagnosis, may cause nephrogenic systemic fibrosis (NSF) probably due to the gadolinium ion (Gd3+) released from the GBCAs. However, Gd-binding proteins and related mechanism responsible for Gd toxicity remained to be understood. In this study, NIH-3T3 cells were chosen as a model for Gd exposure assays and identification of Gd-binding proteins. A comparative assay showed that gadolinium chloride (GdCl3) was much more toxic than gadolinium diamide (Gd-DTPA-BMA, a GBCAs). Majority of Gd were absorbed by cells and existed in the fractions of the cell fragment and soluble proteins. High performance liquid chromatography-inductively coupled plasma mass spectrometry(HPLC-ICP-MS), polyacrylamide gel electrophoresis (SDS PAGE) and liquid chromatography-triple time of flight mass spectrometry (LC-Triple TOF) were employed for the identification and characterization of potential Gd-binging proteins. Tubulin was identified as a novel Gd-binding protein in the NIH-3T3 cells. The binding of Gd to tubulin might inhibit assembling of tubulin or depolymerize microtubules in cells. Our results suggested that the formation of microtubules interfered by binding of free Gd3+ to tubulin could be an important molecular mechanism of Gd toxicity.

[3D printed portable gel electrophoresis device for rapid detection of proteins].

The growing demand for rapid, portable, and economical detection methods for environmental analysis has resulted in increasing demands on the portability and miniaturization of analytical instruments. The miniaturization of scientific instruments facilitates analysis in the field of medicine, food, and environment, especially for the under-resourced areas. The gel electrophoresis devices currently available for protein separation are primarily used in laboratories. Miniaturized instruments that can be used for on-site and rapid separation of protein have not yet been reported. In this study, a portable gel electrophoresis device for rapid separation and detection of proteins was developed and manufactured by 3D printing in a laboratory, which was economical, convenient, and quick. First, four kinds of portable gel electrophoresis devices that included three kinds of columnar gel and one slab gel electrophoresis device were designed with computer-aided design software SolidWorks 2017 (Dassault Systemes SE, France); the components including gel tubes, gel plates, and gel electrophoresis tanks were then printed using a 3D printer after optimization of the printing parameters. Then, the performance of the four kinds of gel electrophoresis devices was investigated using prestained protein molecular weight standards. The results showed that the single-channel slab gel electrophoresis design can quickly separate proteins with the best separation efficiency. Moreover, the effect of different separation gel lengths (5, 10, 15, and 20 mm) on protein separation was studied and it was found that 10% separation gels with a length of 5 mm could effectively separate prestained protein molecular weight standards (in the range of 15-250 kD) in 20 minutes. Next, the battery was optimized for the portable GE device and a 25 V lithium battery (70 mm×60 mm×40 mm) was used as the power supply, which could provide a constant voltage of 25 V for 100 hours during gel electrophoresis. Then, the One-Step BlueTM reagent (Biotium, USA) was used to color the separation results of the five standard proteins (carbonic anhydrase, ovalbumin, bovine serum albumin, conalbumin, ribonuclease A), and the results were recorded by mobile phone. Finally, the proposed gel electrophoresis device was compared with the commercial device. The results showed that the two devices are comparable; however, the slab gel electrophoresis was faster, portable, and economical. In summary, this research designed and manufactured a portable gel electrophoresis device using 3D printing technique, which can be used for on-site analysis and detection of proteins. The device presents the following advantages compared with the commercial devices:1) small and portable:the size of the electrophoresis tank of the device is only 15 mm×20 mm×17 mm and the 25 V lithium battery has a working time of approximately 100 hours; 2) low cost:it can be processed in 5 hours using 3D printing technology, with 10 mL of printing material while the total cost is less than 400 RMB; 3) fast separation:this device can quickly achieve protein separation compared with commercial devices and can further use multiple electrophoresis tanks in parallel to analyze more samples at the same time. Besides, this research also highlights the advantages of 3D printing for the development of miniaturized analytical equipment. Though this study has achieved preliminary results for rapid separation of proteins using gel electrophoresis devices, the quantitative analysis of proteins following protein detection and the application of more samples need further research. Meanwhile, the continued application of 3D printing technology will promote the development of miniaturized and portable experimental equipment.

Bacterial resistance to lead: Chemical basis and environmental relevance.

Natural bacterial isolates from heavily contaminated sites may evolve diverse tolerance strategies, including biosorption, efflux mechanism, and intracellular precipitation under the continually increased stress of toxic lead (Pb) from anthropogenic activities. These strategies utilize a large variety of functional groups in biological macromolecules (e.g., exopolysaccharides (EPSs) and metalloproteins) and inorganic ligands, including carboxyl, phosphate and amide groups, for capturing Pb. The amount and type of binding sites carried by biologically originated materials essentially determines their performance and potential for Pb removal and remediation. Many factors, e.g., metal ion radius, electronegativity, the shape of the cell surface sheath, temperature and pH, are thought to exert significant influences on the abovementioned interactions with Pb. Conclusively, understanding the chemical basis of Pb-binding in these bacteria can allow for the development of effective microbial Pb remediation technologies and further elucidation of Pb cycling in the environment.

3D printed gel electrophoresis device coupling with ICP-MS for online separation and detection of metalloproteins.

We successfully developed a strategy to combine a customized gel electrophoresis device with ICP-MS for online separation and detection of metalloproteins. The self-designed horizontal column gel electrophoresis device was rapidly and easily fabricated in the laboratory via 3D printing with a low cost. The feasibility of 3D printing to fabricate this device was investigated by offline separation of commercial protein standards. And a better separation efficiency was found when using gel tubes printed with higher printing precision. As a proof-of-concept, the performance of the whole system is demonstrated by online separation and detection of both iodinated protein standards and proteins in rat blood plasma samples. Benefits from 3D printing, customized modification or further optimization can be readily achieved for a better protein separation and detection efficiency.

Characterization of mercury-binding proteins in rat blood plasma.

Mercury-binding protein profiles in rat plasma at different levels of mercury exposure in vitro and in vivo were systematically investigated using column gel electrophoresis coupled with inductively coupled plasma-mass spectrometry. The current finding provided various protein candidates that may play critical roles in mercury binding and transporting in plasma.