The role of Nrf2 in the alteration of tight junction protein expression in choroid plexus epithelial cells created by lanthanum-activated MMP9 / 中华劳动卫生职业病杂志

Objective: To investigate the effect of nuclear factor erythroid 2-related factor 2 (Nrf2) in the alteration of tight junction protein expression in choroid plexus epithelial cells created by lanthanum-activated matrix metalloproteinase 9 (MMP9) . Methods: In October 2020, immortalized rat choroid plexus epithelial cell line (Z310) cells were used as the blood-cerebrospinal fluid barrier in vitro, and were divided into control group and 0.125, 0.25, 0.5 mmol/L lanthanum chloride (LaCl(3)) treatment group. After treating Z310 cells with different concentrations of LaCl(3) for 24 hours, the morphological changes of Z310 cells were observed under inverted microscope, the protein expression levels of MMP9, occludin and zonula occludens-1 (ZO-1) were observed by cellular immunofluorescence method, and the protein expression levels of MMP9, tissue inhibitors of metalloproteinase1 (TIMP1) , occludin, ZO-1 and Nrf2 were detected by Western blotting. The level of reactive oxygen species (ROS) in cells was detected by flow cytometry. Results: Compared with the control group, Z310 cells in the LaCl(3) treatment group were smaller in size, with fewer intercellular junctions, and more dead cells and cell fragments. The expression level of MMP9 protein in cells treated with 0.25 and 0.5 mmol/L LaCl(3) was significantly higher than that in the control group (P<0.05) , and the expression level of TIMP1 and tight junction proteins occudin and ZO-1 was significantly lower than that in the control group (P<0.05) . Compared with the control group, the ROS production level in the 0.25, 0.5 mmol/L LaCl(3) treatment group was significantly increased (P<0.05) , and the Nrf2 protein expression level in the 0.125, 0.25, 0.5 mmol/L LaCl(3) treatment group was significantly decreased (P<0.05) . Conclusion: Lanthanum may increase the level of ROS in cells by down regulating the expression of Nrf2, thus activating MMP9 to reduce the expression level of intercellular tight junction proteins occludin and ZO-1.

Disorder of copper homeostasis induced by lead exposure among mice and intervention effect of quercetin / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of lead exposure on copper and copper metalloenzyme and the intervention effect of quercetin.</p><p><b>METHODS</b>Twenty-four specific pathogen-free male Sprague-Dawley rats of good health were randomly divided into control group (n = 8), lead acetate group (n = 8), and lead acetate + quercetin group (n = 8). The rats in lead acetate group were poisoned by drinking water with 1 g/L lead acetate for 8 weeks, while the rats in control group were fed by drinking water with sodium acetate of the same volume for 8 weeks; the rats in lead acetate+quercetin group were intraperitoneally injected with quercetin (30 mg × kg-1 × d-1) for 8 weeks while drinking water with lead acetate. The Morris water maze was used to test the learning and memory abilities of rats. The lead and copper levels in the serum, hippocampus, cortex, and bone were measured by graphite furnace atomic absorption spectrometry. The level of advanced glycation end products, activity of Cu/Zn superoxide dismutase (SOD), and content and activity of ceruloplasmin (CP) in the hippocampus and serum were measured using a test kit. HE staining was performed to observe the pathological changes in the hippocampus.</p><p><b>RESULTS</b>The Morris water maze test showed that the latency in lead acetate group (52.50±12.04 s) was significantly longer than that in control group (28.08±7.31 s) (P<0.05), and the number of platform crossings was significantly lower in the lead acetate group than in the control group. Compared with those in the control group, the lead levels in the cortex and hippocampus in lead acetate group increased 2.72-fold and 3.79-fold, and the copper in the cortex and hippocampus, and serum free copper levels in lead acetate group increased 1.15-fold, 1.48-fold, and 6.44-fold. Compared with the control group, the lead acetate group had a lower content of CP in the hippocampus (1.23±0.40 U/mg provs0.78±0.08 U/mg pro) and 31.81%and 19.49%decreases in CP content and Cu/Zn SOD activity. Free copper level in serum was positively correlated with the latency and lead levels in the serum, cortex, and hippocampus. The escape latency of rats in lead acetate + quercetin group was decreased by 42.15% (P<0.05). The lead levels in the cortex and hippocampus in lead acetate + quercetin group (0.246 ± 0.58 µg/g and 0.202±0.049 µg/g) were significantly lower than those in lead acetate group (0.391±0.49 µg/g and 0.546±0.120 µg/g), but the free copper and copper levels in the hippocampus and cortex were not significantly reduced. The lead acetate + quercetin group had higher Cu/Zn SOD activity and CP content in the hippocampus than the lead acetate group (P < 0.05). The light microscope observation showed that the number of cells in the hippocampus was reduced with disordered arrangement in the lead acetate group; with quercetin intervention, the hippocampus damage was reduced.</p><p><b>CONCLUSION</b>Lead exposure results in disorder of copper homeostasis, while quercetin may alleviate the damage induced by lead to some extent.</p>

The change of pulmonary surfactant protein of rat following silica exposure / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the change of lung surfactant protein (SP) A,B,C,D of rats following silica dust exposure in order to provide the evidences for the early diagnosis indices or therapy of silicosis.</p><p><b>METHODS</b>60 male SD rats were randomly divided into silica group, and corresponding controls group. Rats in silica group were administrated 1 ml silica solution by intratracheal instillation at dose of 50 mg/ml. Rats in control group were administrated the same amount saline. At 3rd, 7th, 14th, 21st, 28th after silica exposure, serum and bronchoalveolar lavage fluid (BALF) samples were obtained. The concentration of SP-A, SP-B, SP-C, SP-D in serum and BALF were measured by using enzyme immunoassay (ELISA). Meanwhile the levels of total anti-oxidative activity (T-AOC) and hydroxyproline (HYP) in lung tissue were also detected. The pathology of lung tissue was conducted.</p><p><b>RESULTS</b>Compared with control group, SP-A concentration in BALF of silica exposed rat for 3, 14, 21, 28d was significant lower and SP-D concentration in BALF of silica exposed rat for all time points was also lower. The differences were significant (P < 0.05). Meanwhile SP-B level in 7, 14, 21, 28 d silica exposed rats BALF and SP-C level in 14, 21, 28 d silica exposed rats markedly decreased (P < 0.05). In addition compared with control group, SP-A, SP-B and SP-C concentration in serum of silica exposed rat were higher when SP-A for 14, 21, 28 d silica exposure, SP-B for 7, 14, 21 d silica exposure and Sp-C for 7, 14, 21, 28 d exposure. And all difference were significant (P < 0.05). As silica exposure time increased, SP-C concentration in serum showed an increase trend, which showed a time-response relationship (r = 0.618, P = 0.042). However, SP-D concentration in serum of rat for 7, 14, 21, 28d silica exposure were significant lower than that of control group (P < 0.005). And there was a decrease trend with time point exposure regarding of SP-D (r = -0.731, P = 0.016). The HYP content in lung tissue of experiment rats increased at 3rd, 7th, 14th, 21st and 28th day time point and The T-AOC activity in lung tissue decrease at, 7th, 14th, 21st and 28th day time point. The differences were significant (P < 0.05). There was a positive correlation (P = 0.803, P = 0.045) between SP-C in BALF and HYP of silica exposed rats and a negative correlation between SP-D in BALF and HYP (r = -0.867, P = 0.033). No significant correlation were seen between SP-A, SP-B BALF and HYP (y = 0.416, P = 0.28; r = 0.592, P = 0.071). SP-C concentration in BALF and serum all showed an increased trend and a positive correlation was seen (r = 0.539, P = 0.046). The same decrease trend was seen between SP-D in BALF and serum and correlation value was 0.870 (P = 0.034).</p><p><b>CONCLUSION</b>The silica exposure did cause the change of SP content both in BALF and serum. The SP-C and SP-D content in serum might be served as an early effective biomarker of silicosis.</p>

Effects of acrylamide on the permeability of blood cerebrospinal fluid barrier in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the effects of acrylamide on the permeability of blood cerebrospinal fluid barrier (BCB) and tight junction protein ZO-1 of choroid plexus in rats and to provide a theoretical basis for explaining the mechanism of nerve injury induced by acrylamide.</p><p><b>METHODS</b>Thirty two male Sprague-Dawley rats were randomly divided into ACR and control groups. ACR group was exposed to 20 mg/kg ACR daily for 5 days a week by intraperitoneal injection (i.p.) for 4 weeks. Control group was exposed to normal saline. The neurobehavioral tests (including sensatory and motor functions) were performed every week. At the end of exposure, Evan blue (EB) and Sodium fluorescein (NaFI) content in rat CSF were detected for determining the BCB permeability, Real-time PCR was used to measure the expression levels of ZO-1 mRNA in the epithelium cells of choroid plexus, and laser scanning confocal microscope (LSCM) was utilized to observe the distribution of ZO-1 protein.</p><p><b>RESULTS</b>Neurobehavioral tests showed that the tail-flick latencies of ACR group were 27.77% and 53.71% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). The hind lamb splay distances of ACR group were 131.76% and 153.77% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). Evan blue (EB) and Sodium fluorescein (NaFI) content of ACR group were significantly higher than those of control group (P < 0.05). In the 4th week, the expression level of ZO-1 mRNA in ACR group was 0.21 +/- 0.07, which was significantly lower than that (0.31 +/- 0.11) in control group (P < 0.05). In the 4th week, the ZO-1 protein expression level of choroid plexus in ACR group was significantly lower than that in control group (P < 0.05).</p><p><b>CONCLUSION</b>Acrylamide could increased the BCB permeability of rats, which may be involved in the central nervous injury induced by ACR.</p>