Respirable crystalline silica dust exposure and regulated occupational respiratory diseases in the Zambian copper mining sector: a review and recommendations

Background: Exposure to respirable dust is widespread in the mining industry. One of the significant components in dust is respirable crystalline silica (RCS), which causes pulmonary silicosis; RCS exposure is also associated with tuberculosis. The health effects of exposure to RCS in Zambian copper miners are unclear. Objectives: This review describes RCS exposure, associated occupational respiratory diseases, and existing dust exposure management programmes in the Zambian copper mining industry. Research gaps are also identified. Methods: Online search engines (Google Scholar, PubMed, and Web of Science) were used to identify relevant published literature, and governmental databases and websites were searched for information. Results: Only two studies have reported RCS dust exposure in the Zambian copper mining industry, and seven studies describe related diseases. The Zambian Ministry of Health reports on only two occupational respiratory diseases: silicosis and tuberculosis (TB). Zambia does not have an occupational health policy or programmes that protect workers in dusty operations from exposure to RCS. Conclusion: Little is known about exposure to RCS and related occupational diseases in the Zambian copper mining industry. The absence of legislative guidelines for an RCS monitoring programme places copper miners at risk of developing respiratory diseases because of high and uncontrolled RCS levels. An RCS management programme should be developed and implemented to investigate the exposure of miners to RCS, and to promote the implementation of control measures

Simultaneous determination of six aniline compounds in workplace air by high performance liquid chromatography / 中国职业医学

Objective To establish a high performance liquid chromatography (HPLC) method for simultaneous determination of six aniline compounds (ADs) in workplace air. Methods GDH-1 air sampling tube was used to collect six co-existing ADs such as aniline, o-toluidine, N-methylaniline, m-methylaniline, p-methylaniline and N,N-dimethylaniline in the vapor and aerosol of workplace air. The samples were desorbed and eluted using a methanol solution containing 1.00% ammonia water, followed by separation on a C18 chromatographic column and detection using a diode array detector. Results The quantification range of the method was 0.19 -253.50 mg/L, with the correlation coefficient of 0.999 9 for all six ADs. The minimum detection range was 0.02-0.06 mg/m3, and the minimum quantitation range was 0.04-0.19 mg/m3 [both calculated for a 15.0 L sample with a desorption (elution) solution volume of 3.00 mL]. The average desorption and elution efficiencies were 92.15%-104.41% (silica gel) and 94.29%-104.29% (filter membrane). The intra-assay relative standard deviation (RSD) ranged from 0.90%-9.72% (silica gel) and 0.57%-6.96% (filter membrane). The inter-assay RSD ranged from 2.03%-9.78% (silica gel) and 2.50%-8.62% (filter membrane). The samples were stable at room temperature for seven days. Conclusion This method can be used for the simultaneous determination of six ADs in workplace air.

Physicomechanical Properties of Resin-Based Pit and Fissure Sealants Reinforced with Rice Husk Derived Nano Silica and Nanohydroxyapatite

@#Resin-based pit fissure sealants (RBS) are used to prevent occlusal caries in children. The success of RBS in preventing dental caries is largely influenced by its retention on the tooth surface, which is also affected by its physicomechanical properties. The physicomechanical properties of RBS can be enhanced through the addition of fillers. With the advent of nanofillers, the physicomechanical properties were improved without altering RBS flowability. The present study developed an RBS with a 70 wt% resin matrix and 30 wt% nanofillers. The resin matrix consisted of urethane dimethacrylate (55 wt%), triethylene glycol dimethacrylate (45 wt%), camphoroquinone (0.3 wt%), and 2-(dimethylamino) ethyl methacrylate (0.7 wt%). Silane-treated rice husk-derived nanosilica (20 wt%) and nanohydroxyapatite (10 wt%) were added as fillers. Clinpro, Fissurit FX, and an unfilled sealant were controls. All RBS were tested for surface roughness, Vickers hardness, flexural strength, and flowability. Statistical analysis with oneway ANOVA revealed significant differences between groups in surface roughness, hardness, flowability (p < 0.001), flexural strength, and flexural modulus (p < 0.05). Experimental sealants had higher flexural strength (78 MPa) and flow distance (29.05+1.16 mm) than commercial controls.However, the surface roughness of experimental sealants (0.25+0.08 μm) was higher than Clinpro (0.087+0.027 μm) but lesser than Fissurit FX (0.35+0.19 μm). The Vickers hardness of experimental sealants (23+1.63 VHN) was less than Fissurit FX (28.80+1.69 VHN) but higher than Clinpro (21.74+1.68 VHN). This novel RBS had physicomechanical properties comparable to commercial sealants. The use of nanosilica from rice husk makes this pit and fissure sealer sustainable and environmentally friendly in dentistry.

Application research and design strategy on smart responsive mesoporous silica anti-tumor nanodelivery systems / 药学学报

Malignant tumors are major diseases that endanger human health. Due to their complex and variable microenvironment, most anti-tumor drugs cannot precisely reach the focal tissue and be released in a controlled manner. Intelligent responsive nano carriers have become a hot spot in the field of anti-tumor drug delivery systems. As an excellent nano material, mesoporous silica has the advantages of non-toxic, stable, adjustable pore volume and pore diameter, and easy functional modification on the surface. By virtue of its perceptive response to the tumor microenvironment or physiological changes, it can achieve the targeted drug release or controlled drug release of the drug delivery system in the tissue, making it an ideal carrier for intelligent response drug delivery system. In this paper, we review the design strategies and current research status of smart responsive anti-tumor drug delivery systems based on mesoporous silica, in order to provide a reference for the development of anti-tumor drug nanoformulations.

Application of two occupational health risk assessment methods for dust hazards in non-coal underground mines / 环境与职业医学

Background The mining of non-coal underground mines may come into contact with various types of dust, such as lead, zinc, copper, and non-metallic minerals. Dust of various kinds commonly exists in all aspects of mining and selection, and is one of the main occupational hazard groups in non-coal underground mines. Objective To compare the application of two risk assessment methods in the occupational health risk assessment of productive dust in non-coal underground mines, and to provide a reference for the selection of dust hazard health risk assessment methods and the management of dust hazards in non-coal mines. Methods A field investigation of the dust hazards of three typical non-coal underground mining enterprises (lead-zinc mines, copper mines, and fluorite mines) was carried out, and the comprehensive index method and the occupational health risk assessment method from the International Council on Mining and Metals (ICMM) were used to perform risk assessments. The comprehensiveindex method considers the following factors: dust monitoring data, the aerodynamic diameter of dust, hazard control measures, occupational health management, daily usage, and daily exposure time to determine exposure levels. The ICMM method determines the risk level based on the consequences caused by dust, exposure probability, exposure time, and uncertainty coefficient. Kendall consistency test was used to compare agreement between the results generated by the two methods. Results The results generated by the comprehensive index method were as follows: level 3 (medium risk) or level 4 (high risk) for silica dust or lead dust; level 1 (negligible risk) or level 2 (low risk) for other dust (dust with free SiO2 content<10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The risk levels graded by the ICMM method were as follows: level 4 (very high risk) and level 3 (high risk) for exposure to silica dust and lead dust, respectively, and level 1 (tolerable risk) or level 2 (potential risk) for exposure to other dust (dust with free SiO2 content <10% and containing lead, zinc, and copper, using other dust limit values for comparison), fluorspar mixed dust, fluorine and its compounds, zinc oxide, and copper dust. The consistency level between the results graded by the two methods was very high (Kendall W coefficient=0.974, P < 0.05). Conclusion For the occupational health risk assessment of productive dust in non-coal underground mines, the consistency level of risk assessment results between the ICMM method and the comprehensive index method is very high. The ICMM method is more convenient to operate and should be preferred in assessing health risks of dust hazard in non-coal underground mines.

Effect of nanoparticles of different stiffness combined with menthol/curcumol on mechanical properties of bEnd.3 cells / 中国中药杂志

This study aimed to investigate the effects of nanoparticles PLGA-NPs and mesoporous silicon nanoparticles(MSNs) of different stiffness before and after combination with menthol or curcumol on the mechanical properties of bEnd.3 cells. The particle size distributions of PLGA-NPs and MSNs were measured by Malvern particle size analyzer, and the stiffness of the two nanoparticles was quantified by atomic force microscopy(AFM). The bEnd.3 cells were cultured in vitro, and the cell surface morphology, roughness, and Young's modulus were examined to characterize the roughness and stiffness of the cell surface. The changes in the mechanical properties of the cells were observed by AFM, and the structure and expression of cytoskeletal F-actin were observed by a laser-scanning confocal microscope. The results showed that both nanoparticles had good dispersion. The particle size of PLGA-NPs was(98.77±2.04) nm, the PDI was(0.140±0.030), and Young's modulus value was(104.717±8.475) MPa. The particle size of MSNs was(97.47±3.92) nm, the PDI was(0.380±0.016), and Young's modulus value was(306.019±8.822) MPa. The stiffness of PLGA-NPs was significantly lower than that of MSNs. After bEnd.3 cells were treated by PLGA-NPs and MSNs separately, the cells showed fine pores on the cell surface, increased roughness, decreased Young's modulus, blurred and broken F-actin bands, and reduced mean gray value. Compared with PLGA-NPs alone, PLGA-NPs combined with menthol or curcumol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value. Compared with MSNs alone, MSNs combined with menthol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value, while no significant difference was observed in combination with curcumol. Therefore, it is inferred that the aromatic components can increase the intracellular uptake and transport of nanoparticles by altering the biomechanical properties of bEnd.3 cells.

The incidence of artificial stone-related silicosis among interior decoration workers in different countries / 中华劳动卫生职业病杂志

In this paper, 177 cases of artificial stone-related silicosis in interior decoration workers from Israel, Spain, USA, Italy and Australia were analyzed. Interior decoration workers were from small businesses (or workshops), engaged in kitchen and/or bathroom artificial stone countertops cutting, grinding, polishing and other reprocessing. In the working environment, the content of crystalline silica in artificial stone was more than 70%, and the concentration of silica dust exceeded the relevant standards. Most workplaces used dry cutting without ventilation and dust removal and other dust-proof measures, and most workers did not wear qualified respiratory protective equipment. Taking comprehensive measures such as wet operation, ventilation and dust removal, and individual protection can effectively prevent the occurrence of artificial stone-related silicosis.

Identification the key factor of pulmonary fibrosis following silica nanoparticles exposure based on bioinformatics analysis / 中华劳动卫生职业病杂志

Objective: To investigate the main mechanisms of pulmonary fibrosis following silica nanoparticles (SiNPs) exposure through constructing the macrophage-fibroblast model in vitro, which simulated the process of pulmonary fibrosis. Methods: In January 2021, human mononuclear leukemia cells (THP-1) were treated with 0, 25, 50, 100 μg/ml SiNPs for 24 h. The supernatant of THP-1 cells was collected and applied to human embryonic lung fibroblast cells (MRC-5) which divided into control and low, medium and high dose groups at the logarithmic growth stage for 24 h. MRC-5 cell viability was detected by CCK8. The hydroxyproline (Hyp), interleukin 6 (IL-6), interleukin 1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) expression were detected in the supernatants of MRC-5. The changed proteins were detected by liquid-phase mass spectrometry in high dose group. GeneCard database were applied to identity the differential pulmonary fibrosis proteins in high dose group. Gene Ontology (GO) was performed to identity the key biological process in differential pulmonary fibrosis proteins of high dose group. The String database was used to construct the protein-protein interactions (PPI) network of differential pulmonary fibrosis proteins. The APP of CytoHubba was applied to calculate the key protein of differential pulmonary fibrosis proteins in PPI network. Correlation coefficients between key differential pulmonary fibrosis proteins were calculated using Pearson correlation analysis. Western blotting was applied to detect the expression of key proteins of differential pulmonary fibrosis proteins in different groups. Results: CCK8 results showed that MRC-5 cell viability was increasing in low, medium and high dose groups compared with control group (P<0.05). The expression levels of Hyp and IL-1β in different group were increased compared with control group, the expression levels of IL-6 and TNF-α were increased in high dose group compared with control group (P<0.05). GeneCard database identified 26 differential pulmonary fibrosis proteins, which were mainly involved in extracellular matrix hydrolysis, cell inflammatory response, tissue repair, cell proliferation, inflammation response by GO analysis. The APP of CytoHubba was calculated that matrix metalloproteinase 9 (MMP9) and tissue inhibitor metalloproteinase 1 (TIMP1) played an important role in PPI network. The results of correlation analysis showed that MMP9 was correlated with the expression of matrix metalloproteinase 1 (MMP1), matrix metalloproteinase 3 (MMP3), TIMP1 and epidermal growth factor receptor (EGFR) (r=0.97, 0.98, 0.94, 0.93, P<0.05). Western blotting results showed that TIMP1 protein expression was increased in low, medium and high dose groups, while MMP9 protein expression was increased only in high dose group (P<0.05) . Conclusion: Differential expression proteins related with pulmonary fibrosis in MRC-5 cells mainly regulate biological processes of extracellular matrix hydrolysis, tissue repair, and cellular inflammation response following SiNPs exposure. MMP9 and TIMP1 may be the key proteins, which affected the fibrosis process in vitro pulmonary fibrosis model.

Changes of complement fragment C3a and its receptor in lung injury induced by silica nanoparticles / 环境与职业医学

Background Silica nanoparticles (SiNPs) enter the human body through respiratory tract, digestive tract, and skin, causing body damage. Lung is one of the main damaged organs. Objective To observe the expressions of complement activated fragment C3a and its receptor C3aR in the lungs of mice exposed to SiNPs through respiratory tract, and to explore the involvement of C3a/C3aR in lung injury induced by SiNPs exposure. Methods The ultrastructure of SiNPs (particle size 5-20 nm) was determined under a transmission electron microscope, and the hydrodynamic diameter and surface Zeta potential of SiNPs were determined using a nanoparticle size analyzer. A total of 88 SPF C57BL/6J mice were randomly divided into five groups: a blank control group without any treatment (14 mice), a vehicle control group treated with 50 μL stroke-physiological saline solution by intratracheal instillation (14 mice), and three SiNPs exposure groups (low-dose group, medium-dose group, and high-dose group with 20 mice in each group, who were given 50 μL SiNPs suspension of 7, 21, and 35 mg·kg−1 respectively and exposed once every 3 days for 5 times). The mice were anesthetized on day 1 (1-day model group) and day 15 (15-day model group) after exposure, then sacrificed after extraction of bronchoalveolar lavage fluid (BALF), and lung tissues were retained. The morphological changes of lung tissues were observed by HE staining, the expression level of C3a in BALF was detected by enzyme-linked immunosorbent assay, the deposition of C3a and C3aR in lung tissues were observed by immunohistochemistry, the protein expression level of C3aR was determined by Western blotting, and the localization and semi-quantitative detection of C3a and C3aR in lung tissues was observed by immunofluorescence. Results SiNPs agglomerated in stroke-physiological saline solution. The average hydrodynamic diameter was (185.60±7.39) nm and the absolute value of Zeta potential was (43.33±0.76) mV. The condition of mice in the 1-day model group and the 15-day model group was good, while 2 mice died in the medium-dose group of the 1-day model group due to misoperation. The autopsy results of the two mice showed congestion of the lung tissue, emphysema, and no imperfection of trachea integrity. No death was observed in other dose groups. The HE staining results showed pathological damage to the mouse lung, including alveolar wall thickening and inflammatory cell infiltration after SiNPs exposure. The pathological damage became more serious with the increase of dose. Regarding pathological changes, the 15-day model group was slightly relieved compared with the 1-day model group, but there were still pathological changes. The enzyme-linked immunosorbent assay results showed that there was no difference in the expression level of C3a between the blank control group and the vehicle control group (P＞0.05), the expression levels of C3a in the medium-dose group and the high-dose group were significantly higher than that in the vehicle control group (P<0.05). The immunohistochemistry results showed that C3a deposition was consistent with the enzyme-linked immunosorbent assay results. The Western blotting and the immunohistochemistry results showed that C3aR expression was low in the blank control group and the vehicle control group, while the expression in each dose group tended to increase with the increase of dose. The immunofluorescence results showed that the fluorescence signals of C3a and C3aR were weak in the blank control group and the vehicle control group in the 1-day model group and the 15-day model group, while the fluorescence signals in the lung tissues of mice in the SiNPs exposure groups tended to increase with the increase of dose. Conclusion The increased expressions of C3a and C3aR in complement activation may be related to lung injury induced by intratracheal instillation of SiNPs, suggesting that C3a/C3aR may be involved in lung injury induced by SiNPs exposure.

Preparation and properties of silica/hydroxyapatite whiskers porous ceramics scaffold / 中国修复重建外科杂志

OBJECTIVE@#To investigate the preparation and properties of the novel silica (SiO 2)/hydroxyapatite (HAP) whiskers porous ceramics scaffold.@*METHODS@#The HAP whiskers were modified by the SiO 2 microspheres using the Stöber method. Three types of SiO 2/HAP whiskers were fabricated under different factors (for the No.1 samples, the content of tetraethoxysilane, stirring time, calcination temperature, and soaking time were 10 mL, 12 hours, 560℃, and 0.5 hours, respectively; and in the No.2 samples, those were 15 mL, 24 hours, 650℃, and 2 hours, respectively; while those in the No.3 samples were 20 mL, 48 hours, 750℃, and 4 hours, respectively). The phase and morphology of the self-made HAP whisker and 3 types of SiO 2/HAP whiskers were detected by the X-ray diffraction analysis and scanning electron microscopy. Taken the self-made HAP whisker and 3 types of SiO 2/HAP whiskers as raw materials, various porous ceramic materials were prepared using the mechanical foaming method combined with extrusion molding method, and the low-temperature heat treatment. The pore structure of porous ceramics was observed by scanning electron microscopy. Its porosity and pore size distribution were measured. And further the axial compressive strength was measured, and the biodegradability was detected by simulated body fluid. Cell counting kit 8 method was used to conduct cytotoxicity experiments on the extract of porous ceramics.@*RESULTS@#The SiO 2 microspheres modified HAP whiskers and its porous ceramic materials were prepared successfully, respectively. In the SiO 2/HAP whiskers, the amorphous SiO 2 microspheres with a diameter of 200 nm, uniform distribution and good adhesion were attached to the surface of the whiskers, and the number of microspheres was controllable. The apparent porosity of the porous ceramic scaffold was about 78%, and its pore structure was composed of neatly arranged longitudinal through-holes and a large number of micro/nano through-holes. Compared with HAP whisker porous ceramic, the axial compressive strength of the SiO 2/HAP whisker porous ceramics could reach 1.0 MPa, which increased the strength by nearly 4 times. Among them, the axial compressive strength of the No.2 SiO 2/HAP whisker porous ceramic was the highest. The SiO 2 microspheres attached to the surface of the whiskers could provide sites for the deposition of apatite. With the content of SiO 2 microspheres increased, the deposition rate of apatite accelerated. The cytotoxicity level of the prepared porous ceramics ranged from 0 to 1, without cytotoxicity.@*CONCLUSION@#SiO 2/HAP whisker porous ceramics have good biological activity, high porosity, three-dimensional complex pore structure, good axial compressive strength, and no cytotoxicity, which make it a promising scaffold material for bone tissue engineering.

Silicosis en el Paraguay: la amenaza no se ha ido

La literatura médica nacional guarda una asignatura pendiente relativa a las enfermedades ocupacionales. La silicosis es la neumoconiosis más frecuente y se debe a la inhalación de sílice cristalina y, acorde a la susceptibilidad individual junto a la intensidad de exposición y a la concentración del mineral en el aire, puede originar determinadas formas clínicas. La silicosis crónica es la forma más frecuente y se asocia a varios tipos de labores como cavar pozos y el trabajo en canteras. En los últimos tiempos se relatan otros oficios que pueden originar formas más aceleradas de la enfermedad en tiempos más abreviados de exposición, recrudeciendo brotes preocupantes en adultos en edad laboral. Realizamos una revisión narrativa de trabajos observacionales hechos en el Paraguay con el objetivo de analizar varios aspectos puntualizando las aristas clínicas y demográficas regionales.

Occupational diseases remain an unresolved issue in the national medical literature. The most common form of pneumoconiosis is silicosis, which is brought on by inhaling crystalline silica and depending on the susceptibility of the person, the extent of their exposure, and the concentration of the mineral in the air, silicosis can result in different clinical forms. The most prevalent type, chronic silicosis, is linked to a variety of jobs, including well digging and quarry work. In recent times, other trades have been reported that can cause more accelerated forms of the disease in shorter exposure times, worsening worrying outbreaks in working-age adults. With the intention of assessing various elements and highlighting certain clinical and regional demographic aspects, we performed a narrative review of observational studies conducted in Paraguay.

Silicoproteinosis en paciente minero en Colombia. Reporte de caso / Silicoproteinosis in a mining patient in Colombia. Case report

La silicosis pulmonar es una enfermedad ocupacional que continúa ocasionando morbilidad en el mundo. Debido a que el sílice es el mineral más abundante en la tierra y en las rocas, son numerosas las fuentes de exposición laboral a la inhalación del polvo de sílice en varios sectores industriales. Por su parte, la silicoproteinosis pulmonar es una forma aguda muy rara de silicosis, que puede desarrollarse con un período de latencia más corto en comparación con la silicosis, luego de la primera exposición al sílice, y se caracteriza por un rápido deterioro de la función pulmonar, sin respuesta efectiva a ningún tratamiento. Por su forma de presentación tan atípica, reportamos el caso de un hombre de 58 años, con antecedente laboral de trabajo en mina de extracción de oro en socavón

Pulmonary silicosis is an occupational disease that continues to cause morbidity in the world. Because silica is the most abundant mineral in soil and rock, sources of occupational exposure to inhalation of silica dust are numerous in various industrial sectors. Alternately, pulmonary silicoproteinosis is a very rare acute form of silicosis, which can develop with a shorter latency period compared to silicosis after the first exposure to silica, and is characterized by a rapid deterioration of lung function, without effective response to any treatment. Due to its atypical form of presentation, we report the case of a 58-year-old man, with a history of working in a gold mine

Role of PI3K/Akt/mTOR pathway-mediated macrophage autophagy in affecting the phenotype transformation of lung fibroblasts induced by silica dust exposure / 中南大学学报(医学版)

OBJECTIVES@#The phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway is one of the main signaling pathways related to autophagy. Autophagy plays a key role in the formation of silicosis fibrosis. The phenotypic transformation of lung fibroblasts into myofibroblasts is a hallmark of the transition from the inflammatory phase to the fibrotic phase in silicosis. This study aims to investigate whether the PI3K/Akt/mTOR pathway affects the phenotypic transformation of silicosis-induced lung fibroblasts into myofibroblasts via mediating macrophage autophagy.@*METHODS@#The human monocytic leukemia cell line THP-1 cells were differentiated into macrophages by treating with 100 ng/mL of phorbol ester for 24 h. Macrophages were exposed to different concentrations (0, 25, 50, 100, 200, 400 μg/mL) and different times (0, 6, 12, 24, 48 h) of SiO2 dust suspension. The survival rate of macrophages was measured by cell counting kit-8 (CCK-8) method. Enzyme linked immunosorbent assay (ELISA) was used to measure the contents of transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) in the cell supernatant. The co-culture system of macrophages and HFL-1 cells was established by transwell. A blank control group, a SiO2 group, a LY294002 group, a SC79 group, a LY294002+SiO2 group, and a SC79+SiO2 group were set up in this experiment. Macrophages in the LY294002+SiO2 group were pretreated with LY294002 (PI3K inhibitor) for 18 hours, and macrophages in the SC79+SiO2 group were pretreated with SC79 (Akt activator) for 24 hours, and then exposed to SiO2 (100 μg/mL) dust suspension for 12 hours. The expression of microtubule-associated protein 1 light chain 3 (LC3) protein in macrophages was detected by the immunofluorescence method. The protein expressions of PI3K, Akt, mTOR, Beclin-1, LC3 in macrophages, and collagen III (Col III), α-smooth muscle actin (α-SMA), fibronectin (FN), matrix metalloproteinase-1 (MMP-1), tissue metalloproteinase inhibitor-1 (TIMP-1) in HFL-1 cells were measured by Western blotting.@*RESULTS@#After the macrophages were exposed to SiO2 dust suspension of different concentrations for 12 h, the survival rates of macrophages were gradually decreased with the increase of SiO2 concentration. Compared with the 0 μg/mL group, the survival rates of macrophages in the 100, 200, and 400 μg/mL groups were significantly decreased, and the concentrations of TGF-β1 and TNF-α in the cell supernatant were obviously increased (all P<0.05). When 100 μg/mL SiO2 dust suspension was applied to macrophages, the survival rates of macrophages were decreased with the prolonged exposure time. Compared with the 0 h group, the survival rates of macrophages were significantly decreased (all P<0.05), the concentrations of TGF-β1 and TNF-α in the cell supernatant were significantly increased, and the protein expression levels of Beclin-1 and LC3II were increased markedly in the 6, 12, 24, and 48 h groups (all P<0.05). Immunofluorescence results demonstrated that after exposure to SiO2 (100 μg/mL) dust for 12 h, LC3 exhibited punctate aggregation and significantly higher fluorescence intensity compared to the blank control group (P<0.05). Compared with the blank control group, the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were up-regulated in the SiO2 group (all P<0.05). Compared with the SiO2 group, the protein expressions of PI3K, Akt, and mTOR were down-regulated and the protein expressions of LC3II and Beclin-1 were up-regulated in macrophages (all P<0.05), the contents of TNF-α and TGF-β1 in the cell supernatant were decreased (both P<0.01), and the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were down-regulated (all P<0.05) in the LY294002+SiO2 group. Compared with the SiO2 group, the protein expressions of PI3K, Akt, and mTOR were up-regulated and the protein expressions of LC3II and Beclin-1 were down-regulated in macrophages (all P<0.05), the contents of TNF-α and TGF-β1 in the cell supernatant were increased (both P<0.01), and the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were up-regulated (all P<0.05) in the SC79+SiO2 group.@*CONCLUSIONS@#Silica dust exposure inhibits the PI3K/Akt/mTOR pathway, increases autophagy and concentration of inflammatory factors in macrophages, and promotes the phenotype transformation of HFL-1 cells into myofibroblasts. The regulation of the PI3K/Akt/mTOR pathway can affect the autophagy induction and the concentration of inflammatory factors of macrophages by silica dust exposure, and then affect the phenotype transformation of HFL-1 cells into myofibroblasts induced by silica dust exposure.

Preparation of mesoporous silica nanoparticles with different sizes and study on the correlation between size and toxicity / 药学学报

To investigate the crucial role of particle size in the biological effects of nanoparticles, a series of mesoporous silica nanoparticles (MSNs) were prepared with particle size gradients (50, 100, 150, 200 nm) with the traditional Stober method and adjusting the type and ratio of the silica source. The correlation between toxicity and size-caused biological effects were then further examined both in vitro and in vivo. The results indicated that the prepared MSNs had a uniform size, good dispersal, and ordered mesoporous structure. Hemolytic toxicity was found to be independent of particle size. At the cellular level, MSNs with smaller particle sizes were more readily internalized by cells, which initiated to more intense oxidative stress, therefor inducing higher cytotoxicity, and apoptosis rate. In vivo studies demonstrated that MSNs primarily accumulated in the liver and kidneys of mice. Pharmacokinetic analysis revealed that larger MSNs were eliminated more efficiently by the urinary system than smaller MSNs. The mice's body weight monitoring, blood tests, and pathological sections of major organs indicated good biocompatibility for MSNs of different sizes. Animal welfare and the animal experimental protocols were strictly consistent with related ethics regulations of Zhejiang Chinese Medical University. Overall, this study prepared MSNs with a particle size gradient to investigate the correlation between toxicity and particle size using macrophages and endothelial cells. The study also examined the biosafety of MSNs with different particle sizes in vivo and in vitro, which could help to improve the safety design strategy of MSNs for drug delivery systems.

A preparation strategy for protein-oriented immobilized silica magnetic beads with Spy chemistry for ligand fishing / 药物分析学报

Due to the complexity of bioactive ingredients in biological samples,the screening of target proteins is a complex process.Herein,a feasible strategy for directing protein immobilization on silica magnetic beads for ligand fishing based on SpyTag/SpyCatcher(ST/SC)-mediated anchoring is presented.Carboxyl functional groups on the surface of silica-coated magnetic beads(SMBs)were coupled with SC using the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysulfosuccinimide method,named SC-SMBs.The green fluorescent protein(GFP),as the capturing protein model,was ST-labeled and anchored at a specific orientation onto the surface of SC-SMBs directly from relevant cell lysates via ST/SC self-ligation.The characteristics of the SC-SMBs were studied via electron microscopy,energy dispersive spectroscopy,and Fourier transform infrared spectroscopy.The spontaneity and site-specificity of this unique reaction were confirmed via electrophoresis and fluorescence analyses.Although the alkaline stability of ST-GFP-ligated SC-SMBs was not ideal,the formed isopeptide bond was unbreakable under acidic conditions(0.05 M glycine-HCl buffer,pH 1-6)for 2 h,under 20％ethanol solution within 7 days,and at most temperatures.We,therefore,present a simple and universal strategy for the preparation of diverse protein-functionalized SMBs for ligand fishing,prompting its usage on drug screening and target finding.

Mechanism of silica-induced ROS over synthsis in NLRP3-dependent macrophage pyroptosis / 环境与职业医学

Background Macrophages are essential components of the natural immune system. They play a significant role in resisting foreign bodies in the respiratory tract and maintaining the homeostasis of the internal environment of lung tissue. Objective To investigate the mechanism of macrophage pyroptosis induced by silica dust with different particle sizes. Methods The modified murine macrophage cell line, RAW-ASC cells, was cultured and divided into a blank control group, a lipopolysaccharide (LPS) group (1 μg·mL−1 LPS), a nano-SiO2 group (1 μg·mL−1 LPS+100 μg·mL−1 nano-SiO2), a micro-SiO2 group (1 μg·mL−1 LPS+750 μg·mL−1 micro-SiO2), and a positive control group [1 μg·mL−1 LPS+3 mmol·L−1 adenosine triphosphate (ATP)]. Apart from the blank control group, cells in other groups were pretreated with LPS for 6 h, and then exposed to SiO2 or ATP for 4 h. According to the molecular target NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and reactive oxygen species (ROS), we applied MCC950 (NLRP3 inhibitor) and N-acetyl cysteine (NAC, ROS scavenger) to macrophages. CCK-8 assay was used to detect cell viability; 5-ethynyl-2'-deoxyuridine (EdU) staining was used to detect cell proliferation; lactate dehydrogenase (LDH) assay kit was used to detect LDH in supernatant; calcein AM/PI fluorescent double-staining was applied to evaluate cell rupture; 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescent probe was used to measure the content of ROS; Western blotting was used to measure the expressions of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), Caspase-1, gasdermin D (GSDMD), and interleukin-1β (IL-1β). Results Compared with the blank group, 100 μg·mL-1nano-SiO2 and 750 μg·mL-1micro-SiO2 dust exposure reduced the cell viability to 40% and 68% (P<0.05), and the cell proliferation rate to 30% and 33% (P<0.01), respectively; they also induced cell lysis and ROS release, upregulated NLRP3, ASC, Caspase-1, GSDMD, and IL-1β at protein level (P<0.05), and induced macrophage pyroptosis. After intervening with MCC950 (10 μmol·L-1) and NAC (10 mmol·L-1), the expressions of NLRP3, ASC, Caspase-1, and IL-1β decreased (P<0.05), and, specifically, NAC effectively reduced ROS levels (P<0.05). Conclusion Both nano- and micro-SiO2 dust have cytotoxicity, can upregulate ROS level, activate NLRP3 inflammasome, and promote the release of cytokines, leading to pyroptosis. These results are helpful to reveal the molecular mechanism of macrophage pyroptosis induced by SiO2 dust.

The role of autophagy in pulmonary inflammatory response in silicosis model rats / 中国职业医学

@#Objective To evaluate the role of autophagy in inflammatory response in the lungs of silicosis rats. Methods The specific pathogen-free healthy male Wistar rats were randomly divided into four groups with 10 rats in each group. The rats in the control group were given an equal volume of 0.9% sodium chloride solution; all rats in the silicon dioxide (SiO2 ) group, the SiO2 + 3-methyladenine (3-MA) group, and the SiO2 +rapamycin (RAPA) group were given a mass concentration of 0.05 mg/L of SiO2 suspension (1.0 mL/rat) to establish a rat model of silicosis using non-exposed tracheal instillation method. Two days before SiO2 exposure, the rats in SiO2 +3-MA group were intraperitoneally injected with 3-MA at a dose of 2.5 mg/kg body weight. The rats in the SiO2 +RAPA group were intraperitoneally injected with a dose of RAPA 1.0 mg/kg body weight, once a day, and once every other day after modeling, for a total of 10 injections. The pathological changes in the lung tissue of the rats in each group were evaluated using hematoxylin-eosin and Masson staining. The relative expression levels of transforming growth factor-β (TGF-β) , interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the lung tissue of the rats in each group were detected using enzyme-linked immunosorbent assay. The relative expression levels of microtubule-associated protein 1 light chain 3 (LC3) and yeast autophagy-related gene 6 (Beclin1) in lung tissue of rats in each group were detected by Western blotting. Results The pathological observation of rat lung tissue showed that scattered inflammatory nodules and interstitial inflammatory cells were found in the lung tissue of the rats in the SiO2 group. In the SiO2 +3-MA group, the inflammation in the lung tissue was more severe and the alveolar cavity had viscous secretions. The rats in the SiO2 +RAPA group had less inflammation and smaller inflammatory nodules than the SiO2 group. Compared with the control group, the TNF-α, IL-1β, TGF-β, Beclin1 protein relative expression levels and LC3 Ⅱ/Ⅰ ratio in the lung tissue were increased in the SiO2 group (all P<0.05). Compared with the SiO2 group, the relative expression levels of TGF-β and TNF-α in the lung tissue of the rats increased (all P<0.05), and the ratio of LC3 Ⅱ/Ⅰ and Beclin1 protein relative expression decreased in the SiO2+3-MA group (all P<0.05). Compared with the SiO2+ 3-MA group, the relative expression levels of TNF- α, IL-1β and TGF- β in the lung tissue of the SiO2 +RAPA group were decreased (all P<0.05), and the LC3Ⅱ/Ⅰ ratio and the relative expression level of Beclin1 protein were increased (all P<0.05). Conclusion Autophagy occurs when inflammatory reaction occurs in the lungs of silicosis model rats; autophagy has inhibitory effect on pulmonary inflammation.

PPP2R3A promotes silicosis by regulating the expression of p53 / 中国药科大学学报

@#Silicosis, one of the most serious occupational diseases in the world, is a complex pathological process with multi-cell involvement and multi-factor regulation, and its pathogenesis has not been fully elucidated.Protein phosphatase 2A (PP2A) regulates tumor signaling pathways, cell development and cell cycle.The regulatory subunit B of PP2A binds to the core enzyme, resulting in tissue expression specificity and substrate specificity of the PP2A holoenzyme complex.Protein phosphatase 2A regulatory subunit B"α (PPP2R3A) is a subunit of PP2A regulatory subunit B", which is a regulator of cell proliferation.However, the role of PPP2R3A in pulmonary fibrosis is still unclear.In this study, the pulmonary fibrosis model was established by endotracheal infusion of silica (SiO2, 250 mg/kg).Human pulmonary fibroblast-adult cells (HFP-a) were stimulated with 5 ng/mL TGF-β1 to construct fibro-related cell models.The transcription level of Ppp2r3a was detected by qRT-PCR assay.Immunofluorescence and Western blot experiments were performed to detect protein levels.Cell viability was detected by CCK-8 assay.The cell migration ability was detected by scratch test.Experimental results showed that silica nodules and collagen deposition were obvious in the SiO2 group, and the expression of PPP2R3A in lung fibroblasts increased, which could affect cell viability and migration ability, and may promote the progression of pulmonary fibrosis by regulating the expression of p53 signaling pathways.This study provides a new idea for the prevention and treatment of pulmonary fibrosis.

Nanoparticles with rough surface improve the therapeutic effect of photothermal immunotherapy against melanoma

Photothermal therapy has been intensively investigated for treating cancer in recent years. However, the long-term therapeutic outcome remains unsatisfying due to the frequently occurred metastasis and recurrence. To address this challenge, immunotherapy has been combined with photothermal therapy to activate anti-tumor immunity and relieve the immunosuppressive microenvironment within tumor sites. Here, we engineered silica-based core‒shell nanoparticles (JQ-1@PSNs-R), in which silica cores were coated with the photothermal agent polydopamine, and a bromodomain-containing protein 4 (BRD4) inhibitor JQ-1 was loaded in the polydopamine layer to combine photothermal and immune therapy for tumor elimination. Importantly, to improve the therapeutic effect, we increased the surface roughness of the nanoparticles by hydrofluoric acid (HF) etching during the fabrication process, and found that the internalization of JQ-1@PSNs-R was significantly improved, leading to a strengthened photothermal killing effect as well as the increased intracellular delivery of JQ-1. In the animal studies, the multifunctional nanoparticles with rough surfaces effectively eradicated melanoma via photothermal therapy, successfully activated tumor-specific immune responses against residual tumor cells, and further prevented tumor metastasis and recurrence. Our results indicated that JQ-1@PSNs-R could serve as an innovative and effective strategy for combined cancer therapy.

Chiral mesoporous silica nano-screws as an efficient biomimetic oral drug delivery platform through multiple topological mechanisms

In the microscale, bacteria with helical body shapes have been reported to yield advantages in many bio-processes. In the human society, there are also wisdoms in knowing how to recognize and make use of helical shapes with multi-functionality. Herein, we designed atypical chiral mesoporous silica nano-screws (CMSWs) with ideal topological structures (e.g., small section area, relative rough surface, screw-like body with three-dimension chirality) and demonstrated that CMSWs displayed enhanced bio-adhesion, mucus-penetration and cellular uptake (contributed by the macropinocytosis and caveolae-mediated endocytosis pathways) abilities compared to the chiral mesoporous silica nanospheres (CMSSs) and chiral mesoporous silica nanorods (CMSRs), achieving extended retention duration in the gastrointestinal (GI) tract and superior adsorption in the blood circulation (up to 2.61- and 5.65-times in AUC). After doxorubicin (DOX) loading into CMSs, DOX@CMSWs exhibited controlled drug release manners with pH responsiveness in vitro. Orally administered DOX@CMSWs could efficiently overcome the intestinal epithelium barrier (IEB), and resulted in satisfactory oral bioavailability of DOX (up to 348%). CMSWs were also proved to exhibit good biocompatibility and unique biodegradability. These findings displayed superior ability of CMSWs in crossing IEB through multiple topological mechanisms and would provide useful information on the rational design of nano-drug delivery systems.