Benzo[a]pyrene-enhanced mutagenesis by asbestos in the lung of lambda-lacI transgenic rats

To study the suspected mechanism of the interaction between tobacco smoking and asbestos exposure in the modulation of cancer risk, the mutagenic potential of asbestos in combination with the tobacco smoke carcinogen benzo[a]pyrene (B[a]P) was examined in vivo in the rat lung. B[a]P was administered intratracheally in one set of experiments, or by two daily intraperitoneal injections in another set of experiments, to lambdalacI transgenic rats, together with 1, 2 or 4 x 2 mg amosite in one experiment. In the first experiment, the combined action of amosite and B[a]P caused a synergistic (superadditive) increase of mutation frequency in the lung, as compared to groups treated only with asbestos or B[a]P. In the second experiment, i.p. treatment with B[a]P did not significantly alter the mutation frequency induced by amosite, neither after 4 nor after 16 weeks of exposure. The B[a]P-DNA adduct levels were unaffected by amosite co-treatment in both experiments. We assume that the synergistic increase of mutation frequency after intratracheal treatment was due to the mitogenic activities of B[a]P and of amosite. In conclusion, our findings indicate that a weak and delayed mutagenic effect of amosite in rat lung observed in another study was strongly enhanced by the concomitant action of B[a]P. The striking enhancement effect of B[a]P may provide a basis for understanding the suspected synergism of smoking on asbestos carcinogenesis.     

Mutagenesis by man-made mineral fibres in the lung of rats

The potential of two asbestos substitute mineral fibres--rock (stone) wool RW1 and glass wool MMVF10--to induce gene mutations, DNA strand breaks, inflammation and oxidative stress has been studied in rats. Male homozygous lamda-lacI transgenic F344 rats were intratracheally instilled with single doses of 1 and 2 mg/animal of fibres or with multiple doses of 2 mg/animal administered weekly on four consecutive weeks (8 mg in total). Exposure to RW1 fibres for 16 weeks significantly increased mutant frequency (MF) in the lung in a dose-dependent manner, while MMVF10 fibres did not exhibit any increase of MF at any dose. RW1 fibres gave a significant increase of MF at a dose of 1 mg. Four weeks after instillation, neither the single nor the multiple doses significantly increased MF for both fibre types. To investigate mechanisms for induction of mutations, other genotoxicity markers and parameters of inflammatory and oxidative damage were determined in relation to MF. A weak correlation of mutagenicity data with other genotoxicity parameters studied was observed. DNA strand breaks as measured by comet assay were increased in alveolar macrophages and lung epithelial cells of RW1 and MMVF10 treated rats. RWl fibres caused more extensive lung inflammation as measured by release of neutrophils into broncho-alveolar lavage fluid than MMVF10 fibres. The effects were observed 16 weeks post-exposure, indicating a persistence of the pathogenic process during the exposure period. Only minor differences in the extent of inflammatory processes were observed between the doses of 2 mg and 4 x 2 mg, suggesting that any threshold for inflammation lies below the dose of 2 mg. With the exception of the highest dose of MMVF10 fibres after 16 weeks of exposure, no significant increase of oxidative damage as measured by levels of malondialdehyde in lung tissue was observed. MMVF10 fibres caused weaker inflammation in the lung of rats and did not exhibit any mutagenic effect. We conclude that a weak but chronic inflammation (more likely than acute inflammation or direct oxidative damage) in the lung tissue of fibre treated rats characterized by moderate influx of inflammatory cells into BAL is probably responsible for the observed mutagenic effect of RW1 fibres.     

Asbestos and cigarette smoke cause increased DNA strand breaks and necrosis in bronchiolar epithelial cells in vivo

Coexposures to asbestos and cigarette smoke cause increased risks of lung cancer in asbestos workers. Although these carcinogens cause DNA damage to epithelial cells in vitro via generation of reactive oxygen species (ROS), it is unclear whether they cause injury to bronchiolar epithelial cells (i.e., the target cells of lung cancers in vivo). We exposed rats to amosite asbestos, cigarette smoke, and the two agents in combination for 1, 2, and 14 d. Numbers of cells exhibiting DNA strand breaks in comparison to sham rats were then evaluated in lungs using the terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-biotin nick end labeling (TUNEL) method and by transmission electron microscopy (TEM). Increases in TUNEL-positive, necrotic epithelial cells occurred after exposure to asbestos alone and in an additive fashion after smoke and asbestos in combination. These results indicate that DNA strand breakage and necrosis are prominent mechanisms of injury by asbestos fibers and cigarette smoke in vivo to epithelial cells of the respiratory tract, thus validating in vitro observations from a number of laboratories.     

Age-, gender-, and species-dependent mutagenicity in T cells of mice and rats exposed by inhalation to 1,3-butadiene

Experiments were performed: (i) to investigate potential age- and gender-dependent differences in mutagenic responses in T cells following exposures of B6C3F1 mice and F344 rats by inhalation for 2 weeks to 0 or 1250 ppm butadiene (BD), and (ii) to determine if exposures for 2 weeks to 62.5 ppm BD produce a mutagenic effect in female rats. To evaluate the effect of age on mutagenic response, mutant manifestation curves for splenic T cells of female mice exposed at 8-9 weeks of age were defined by measuring Hprt mutant frequencies (MFs) at multiple time points after BD exposure using a T cell cloning assay and comparing the resulting mutagenic potency estimate (calculated as the difference of areas under the mutant manifestation curves of treated versus control animals) to that reported for female mice exposed to BD in the same fashion beginning at 4-5 weeks of age. The shapes of the mutant T cell manifestation curves for spleens were different [e.g., the maximum BD-induced MFs in older mice (8.0+/-1.0 [S.D.]x10(-6)) and younger mice (17.8+/-6.1 x 10(-6)) were observed at 8 and 5 weeks post-exposure, respectively], but the mutagenic burden was the same for both age groups. To assess the effect of gender on mutagenic response, female and male rodents were exposed to BD at 4-5 weeks of age and Hprt MFs were measured when maximum MFs are expected to occur post-exposure. The resulting data demonstrated that the pattern for mutagenic susceptibility from high-level BD exposure is female mice>male mice>female rats>male rats. Exposures of female rats to 62.5 ppm BD caused a minor but significant mutagenic response compared with controls (n=16/group; P=0.03). These results help explain part of the differing outcomes/interpretations of data in earlier Hprt mutation studies in BD-exposed rodents.     

Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats

In an attempt to examine the interaction of man-made mineral fibres with benzo[a]pyrene (B[a]P), homozygous X-lacI transgenic F344 rats were intratracheally treated with rock (stone) wool RWI and glass wool MMVF 10 fibres together with B[a]P. To analyze the induction of gene mutations by fibres and B[a]P in lung, single doses of 1 and 2 mg fibres/animal or multiple doses of 2 mg fibres/animal were administered weekly on 4 consecutive weeks (total dose 8 mg/animal). B[a]P (10 mg/animal) was administered either simultaneously with fibres (for single dose treatment with fibres) or together with the last fiber treatment (for multiple dose treatment with fibres). Animals were scarified 4 weeks after the last treatment. Benzo[a]pyrene administered simultaneously with RW1 fibres exhibited a strong synergistic effect on mutagenicity, the observed mutant frequency (MF) being more than three-fold higher than the net sum of the MF induced after separate administration of both agents. Our data suggest that DNA adducts induced by simultaneous B[a]P and fiber treatment lead to a strong increase in mutatant frequencies.     

吸入维生素A和皮质激素对大鼠哮喘性肺炎的疗效及TSLP表达的影响

目的:观察胸腺与肺的胸腺基质淋巴细胞生成素(TSLP)和Th因子在病程发展中变化,分析吸入维生素A(VA)与皮质激素对哮喘性肺炎疗效。方法:卵蛋白激发大鼠哮喘4周后休息1周,VA与皮质激素吸入治疗1周,吸入90%乙醇液作为哮喘组。通过免疫荧光染色、组织化学染色等法检查胸腺与肺。结果:激发第4～5周后,哮喘组胸腺与肺TSLP阳性细胞、肺泡巨噬细胞(AM)较多,胸腺和脾增生,血Th2因子升高,肺部炎症逐渐加重;VA组第4周胸腺与肺TSLP和Th2因子表达均较低;第5周TSLP轻度增加,胸腺、脾T细胞区增生由强转弱,AM明显增多,肺炎症逐渐消退。激素组第4～5周胸腺和肺TSLP、Th2因子表达低,胸腺、脾增生渐强。AM数量少,肺炎症渐重。结论:激发哮喘期间TSLP表达增强伴有Th2类反应,VA和皮质激素均抑制TSLP与Th2因子表达,但VA促进T淋巴细胞增生与AM清除抗原功能,停药后肺炎症逐渐消退;皮质激素停药后炎症加重。     

Induction of rat hepatic drug metabolizing enzymes by dimethylcyclosiloxanes

Low molecular weight dimethylcyclosiloxanes (DMCS) are important precursors in the synthesis of polydimethysiloxane polymers widely used in industry, and in medical and personal care products. The objective of this study was to characterize the ability of two DMCS, octamethylcyclosiloxane (D4) and decamethylcyclopentasiloxane (D5) to induce drug metabolizing enzymes in rats. Male and female Sprague-Dawley rats were administered 1, 5, 20, or 100 mg/kg D4 or D5 in corn oil daily by gavage for 4 days. Changes in the levels of activity and/or immunoreactivity of CYP1A1/2, CYP2B1/2, CYP3A1/2 and NADPH cytochrome P450 reductase in liver microsomes were examined. Significant increases were observed in the liver to body weight ratio in female rats administered either D4 or D5 at doses > or = 20 mg/kg. Increases in the liver to body weight ratio were observed in male rats treated with > or = 100 mg/kg D5 but not with D4. Relatively large increases in CYP2B1/2 enzymatic activity and immunoreactive protein were observed with increasing concentrations of both D4 and D5. Significant increases in 7-pentoxyresorufin O-depentylase (PROD) activity were also detected in male and female rats given D4 at doses > or = 5 mg/kg. D5 increased PROD activity in male rats at doses > or = 20 mg/kg and in female rats at doses > or = 5 mg/kg. 7-Ethoxyresorufin O-deethylase (EROD) activity was increased in both male and female rats receiving > or = 20 mg/kg D4 or > or = 5 mg/kg D5; however, no changes were detected in CYP1A1/2 immunoreactive protein in rats of either sex. D4 and D5 caused significant increases in CYP3A1/2 immunoreactive protein in only male rats treated with 100 mg/kg of either compound. However, significant increases were detected in CYP3A1/2 immunoreactive protein in female rats at D4 doses > or = 20 mg/kg and D5 doses > or = 5 mg/kg. Induction of NADPH cytochrome P-450 reductase immunoreactive protein was observed with D4 in female rats and in both male and female rats with D5. Induction of CYP2B/1/2, CYP3A1/2 and NADPH cytochrome P450 reductase was observed in rats treated with 50 mg/kg phenobarbital by intraperitoneal injection. Maximal CYP2B induction detected with D4 was approximately 50% of the increase observed with phenobarbital. In summary, D4 and D5 induced CYP2B1/2 in adult rat liver in a manner similar to that observed with phenobarbital; however, differences were observed between D4 and D5 in their ability to induce CYP3A1/2 and NADPH cytochrome P450 reductase. Female rats were more sensitive to the inductive properties of low doses of both DMCS than male rats whereas male rats were more responsive to phenobarbital induction.     

Cytogenetic response to asbestos fibers in cultured human primary mesothelial cells from 10 different donors

The ability of amosite asbestos fibers to induce chromosomal aberrations in human primary mesothelial cells obtained from pleural effusions of 10 noncancerous patients was investigated. The glutathione S-transferase M1 (GSTM1) genotypes of the patients were determined, since the GSTM1 null genotype has been associated with increased susceptibility to lung cancer and chemically induced cytogenetic damage. Four of the patients represented the GSTM1 null genotype, and six the GSTM1 positive genotype. Successful chromosome aberration analyses were obtained from six cases, three of them with the GSTM1 null genotype. The level of aberrant cells in unexposed cultures ranged from 2.0% to 7.5%. Statistically significant increases (2.3–3.0-fold compared to controls) in the number of aberrant cells were observed in two cases only: in one case treated with 1 μg/cm² of amosite, and in another treated with 2 μg/cm² of amosite. Cell cultures from four individuals showed minor or no increases in the numbers of aberrant cells in the doses tested (1 and 2 μg/cm²). Chromosome breaks were the major type of aberration. The amosite exposed cells with significantly increased aberrations were from patients with GSTM1 positive genotypes. Two cases that showed no cytogenetic response to asbestos fibers were of the GSTM1 null genotype. Thus, our results suggest that the lack of the GSTM1 gene does not render human mesothelial cells more susceptible to chromosomal damage induced by asbestos. GSTM1 null cells appeared, however, to be more sensitive to the growth inhibitory effects of asbestos than did GSTM1 positive cells. Variation in the cytogenetic response of human primary mesothelial cells to asbestos fibers was observed to exist, but the fibers do not appear to be potent inducers of structural chromosomal aberrations in these cells. It remains to be established whether individual sensitivity to asbestos fibers, due to specific genetic traits, exists.     

Airway epithelial NF-kappaB activation modulates asbestos-induced inflammation and mucin production in vivo

To investigate the role of bronchiolar epithelial NF-kappaB activity in the development of inflammation and fibrogenesis in a murine model of asbestos inhalation, we used transgenic (Tg) mice expressing an IkappaBalpha mutant (IkappaBalphasr) resistant to phosphorylation-induced degradation and targeted to bronchial epithelium using the CC10 promoter. Sham and chrysotile asbestos-exposed CC10-IkappaBalphasr Tg(+) and Tg(-) mice were examined for altered epithelial cell proliferation and differentiation, cytokine profiles, lung inflammation, and fibrogenesis at 3, 9, and 40 days. KC, IL-6 and IL-1beta were increased (p < or = 0.05) in bronchoalveolar lavage fluid (BALF) from asbestos-exposed mice, but to a lesser extent (p < or = 0.05) in Tg(+) vs Tg(-) mice. Asbestos also caused increases in IL-4, MIP-1beta, and MCP-1 in BALF that were more elevated (p < or = 0.05) in Tg(+) mice at 9 days. Differential cell counts revealed eosinophils in BALF that increased (p < or = 0.05) in Tg(+) mice at 9 days, a time point corresponding with significantly increased numbers of bronchiolar epithelial cells staining positively for mucus production. At all time points, asbestos caused increased numbers of distal bronchiolar epithelial cells and peribronchiolar cells incorporating the proliferation marker, Ki-67. However, bronchiolar epithelial cell and interstitial cell labeling was diminished at 40 days (p < or = 0.05) in Tg(+) vs Tg(-) mice. Our findings demonstrate that airway epithelial NF-kappaB activity plays a role in orchestrating the inflammatory response as well as cell proliferation in response to asbestos.     

S-allyl cysteine attenuated CCl4-induced oxidative stress and pulmonary fibrosis in rats

This study examined effects of S-allyl cysteine (SAC) on carbon tetrachloride (CCl4)-induced interstitial pulmonary fibrosis in Wistar rats. CCl4 (0.5 ml/kg) was intraperitoneally injected into rats twice a week for 8 weeks, and SAC (50, 100, or 200 mg/kg), N-acetyl cysteine (NAC, 200 or 600 mg/kg), or L-cysteine (CYS, 600 mg/kg) were orally administrated to rats everyday for 8 weeks. SAC significantly reduced the increases of transforming growth factor beta, lipid peroxides, AST, and ALT in plasma, induced by CCl4. Although CCl4 is mainly metabolized by hepatic cytochrome P450, CCl4 induced systemic inflammation and some organ fibrosis. SAC dose-dependently and significantly attenuated CCl4-induced systemic inflammation and fibrosis of lung. SAC also inhibited the decrease of thiol levels, the increase of inducible nitric oxide synthase expression, the infiltration of leukocytes, and the generation of reactive oxygen species in lungs. Although NAC and CYS attenuated CCl4-induced pulmonary inflammation and fibrosis, the order of preventive potency was SAC > NAC > CYS according to their applied doses. These results indicate that SAC is more effective than other cysteine compounds in reducing CCl4-induced lung injury, and might be useful in prevention of interstitial pulmonary fibrosis.     

Iron mobilization from asbestos by chelators and ascorbic acid

The ability of chelators and ascorbic acid to mobilize iron from crocidolite, amosite, medium- and short-fiber chrysotile, and tremolite was investigated. Ferrozine, a strong Fe(II) chelator, mobilized Fe(II) from crocidolite (6.6 nmol/mg asbestos/h) and amosite (0.4 nmol/mg/h) in 50 mM NaCl, pH 7.5. Inclusion of ascorbate increased these rates to 11.4 and 4.9 nmol/mg/h, respectively. Ferrozine mobilized Fe(II) from medium-fiber chrysotile (0.6 nmol/mg/h) only in the presence of ascorbate. Citrate and ADP mobilized iron (ferrous and/or ferric) from crocidolite at rates of 4.2 and 0.3 nmol/mg/h, respectively, which increased to 4.8 and 1.0 nmol/mg/h in the presence of ascorbate. Since ascorbate alone mobilized iron from crocidolite (0.5 nmol/mg/h), the increase appeared to result from additional chelation by ascorbate. Citrate also mobilized iron from amosite (1.4 nmol/mg/h) and medium-fiber chrysotile (1.6 nmol/mg/h). Mobilization of iron from asbestos appeared to be a function not only of the chelator, but also of the surface area, crystalline structure, and iron content of the asbestos. These results suggest that iron can be mobilized from asbestos in the cell by low-molecular-weight chelators. If this occurs, it may have deleterious effects since this could result in deregulation of normal iron metabolism by proteins within the cell resulting in iron-catalyzed oxidation of biomolecules.     

吸烟对大鼠肺组织B7-1/B7-2及其相关配体表达的影响

目的通过研究吸烟对大鼠肺组织B7-1/B7-2及其相关配体表达的影响,探讨专职抗原提呈细胞（APC）在吸烟所致肺部慢性炎症发生发展中的作用。方法将30只健康雄性Wistar大鼠随机分为不吸烟组、吸烟6周组和吸烟12周组,每组10只。采用免疫组化半定量法测定大鼠气道周围肺间质中慢性炎症细胞胞膜B7-1、B7-2、CD28和CTLA-4的表达水平。结果吸烟6周组与吸烟12周组大鼠肺组织B7-1、B7-2、CD28和CTLA-4表达量较不吸烟组均显著增高（P〈0.01）,吸烟12周组较吸烟6周组表达量也均增高（P〈0.01）,随吸烟时间的延长各指标表达量均呈上升趋势。结论吸烟可引起大鼠肺组织B7/CD28/CTLA-4表达水平的增高,提示APC可能在吸烟所致肺部慢性炎症发生发展中起重要作用。     

The fate of chrysotile-induced multipolar mitosis and aneuploid population in cultured lung cancer cells

Chrysotile is one of the six types of asbestos, and it is the only one that can still be commercialized in many countries. Exposure to other types of asbestos has been associated with serious diseases, such as lung carcinomas and pleural mesotheliomas. The association of chrysotile exposure with disease is controversial. However, in vitro studies show the mutagenic potential of chrysotile, which can induce DNA and cell damage. The present work aimed to analyze alterations in lung small cell carcinoma cultures after 48 h of chrysotile exposure, followed by 2, 4 and 8 days of recovery in fiber-free culture medium. Some alterations, such as aneuploid cell formation, increased number of cells in G2/M phase and cells in multipolar mitosis were observed even after 8 days of recovery. The presence of chrysotile fibers in the cell cultures was detected and cell morphology was observed by laser scanning confocal microscopy. After 4 and 8 days of recovery, only a few chrysotile fragments were present in some cells, and the cellular morphology was similar to that of control cells. Cells transfected with the GFP-tagged α-tubulin plasmid were treated with chrysotile for 24 or 48 h and cells in multipolar mitosis were observed by time-lapse microscopy. Fates of these cells were established: retention in metaphase, cell death, progression through M phase generating more than two daughter cells or cell fusion during telophase or cytokinesis. Some of them were related to the formation of aneuploid cells and cells with abnormal number of centrosomes.     

Effects of elastase-induced emphysema on airway responsiveness to methacholine in rats

We examined the effects of elastase-induced emphysema on lung volumes, pulmonary mechanics, and airway responses to inhaled methacholine (MCh) of nine male Brown Norway rats. Measurements were made before and weekly for 4 wk after elastase in five rats. In four rats measurements were made before and at 3 wk after elastase; in these same animals the effects of changes in end-expiratory lung volume on the airway responses to MCh were evaluated before and after elastase. Airway responses were determined from peak pulmonary resistance (RL) calculated after 30-s aerosolizations of saline and doubling concentrations of MCh from 1 to 64 mg/ml. Porcine pancreatic elastase (1 IU/g) was administered intratracheally. Before elastase RL rose from 0.20 +/- 0.02 cmH2O.ml-1.s (mean +/- SE; n = 9) to 0.57 +/- 0.06 after MCh (64 mg/ml). A plateau was observed in the concentration-response curve. Static compliance and the maximum increase in RL (delta RL64) were significantly correlated (r = 0.799, P less than 0.01). Three weeks after elastase the maximal airway response to MCh was enhanced and no plateau was observed; delta RL64 was 0.78 +/- 0.07 cmH2O.ml-1.s, significantly higher than control delta RL64 (0.36 +/- 0.7, P less than 0.05). Before elastase, increase of end-expiratory lung volume to functional residual capacity + 1.56 ml (+/- 0.08 ml) significantly reduced RL at 64 mg MCh/ml from 0.62 +/- 0.05 cmH2O.ml-1.s to 0.50 +/- 0.03, P less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential effects of tumor necrosis factor and asbestos fibers on manganese superoxide dismutase induction and oxidant-induced cytotoxicity in human mesothelial cells

We compared induction of manganese superoxide dismutase (MnSOD) by asbestos fibers and tumor necrosis factor (TNF) using cultures human mesothelial cells. Transformed pleural mesothelial cells (MET 5A) were exposed for 48 h to amosite asbestos fibers (2 g/cm²), to TNF (10 Ng/ml), and to the combination of these two. TNF and amosite+TNF caused significant MnSOD mRNA upregulation. Similarly MnSOD specific activity was increased by TNF (290% increase) and the amosite+TNF combination (313% increase) but not by amosite alone. In cell injury experiments, amosite and amosite+TNF exposures caused significant cell membrane injury when assessed by lactate dehydrogenase release, which was 31% and 57% higher than in the unexposed cells. However, only the amosite+TNF combination caused significant depletion of cellular high-energy nucleotide when expressed as percentage of [¹⁴C]denine labeling in cellular high-energy nucleotides. The nucleotide levels were 91.5 ± 2.0% in the unexposed cells, 89.9 ± 3.9% in amosite-exposed cells, 90.1 ± 2.2% in TNF-exposed cells, and 79.8 ± 9.4% in amosite+TNF-exposed Amosite+TNF-exposed cells were also most sensitive to menadione (20 mol/L, 2 h), a compound which generates superoxide radicals intracellularly. In conclusion, our data suggests that in human mesothelial cells inflammatory cytokines but not asbestos fibers alone can cause MnSOD induction. In this study, however amosite asbestos+TNF treatment rendered these cells more vulnerable to oxidant-induced cell damage despite elevated MnSOD activity.Abbreviations MnSOD manganese superoxide dismutase - TNF tumor necrosis factor - LDH lactate dehydrogenase     

甘西鼠尾草对大鼠高原肺动脉高压的干预作用及机制*

目的:探讨甘西鼠尾草(SPM)对大鼠高原肺动脉高压(HAPH)的干预作用及可能的机制。方法:将雄性SD大鼠随机分成对照组、缺氧组、SPM(0.5 g/kg、1 g/kg、2 g/kg)剂量组,每组14只,对照组饲养于西宁(海拔约2260 m),其余组均饲养于玛多县人民医院(海拔约4260 m)。SPM剂量组灌胃不同浓度的SPM(1 ml/100 g),浓度分别为0.5 g/kg、1 g/kg、2 g/kg,对照组和缺氧组灌胃等体积蒸馏水,每日一次,连续4周后,测定大鼠平均肺动脉压(mPAP)并取相同部位肺组织置液氮保存备用。采用RT-PCR法测定每组大鼠肺组织中的细胞增殖核抗原(PCNA)、细胞周期素依赖激酶(CDK4)、细胞周期蛋白D(CyclinD1)、RhoA(Ras同源基因家族成员A)、ROCK1、ROCK2的mRNA表达水平。结果:与对照组比较,缺氧组大鼠mPAP、肺组织中PCNA、CDK4、CyclinD1、RhoA、ROCK1、ROCK2的mRNA表达水平均明显升高(P＜0.01)。与缺氧组比较,SPM剂量组大鼠的mPAP、肺组织中PCNA、CDK4、CyclinD1、RhoA、ROCK1、ROCK2的mRNA表达水平均明显降低(P＜0.05或P＜0.01)。结论:SPM对大鼠HAPH具有一定的预防作用,其机制可能与抑制肺动脉平滑肌细胞过度增殖和RhoA/Rho激酶(ROCK)信号通路过度激活有关。     

Inhibition of myeloid differentiation factor 2 attenuates cardiometabolic impairments via reducing cardiac mitochondrial dysfunction,inflammation, apoptosis and ferroptosis in prediabetic rats

Systemic inflammation is a key mediator of left ventricular dysfunction (LV) in prediabetes via the activation of myeloid differentiation factor 2 (MD2)/toll-like receptor 4 complex. The MD2 inhibitor L6H21 effectively reduced systemic and cardiac inflammation in obese mice. However, its effects on cardiac function and regulated cell death pathways in the heart in prediabetes are still unknown. The prediabetic rats were divided into 3 subgroups to receive vehicle, L6H21 (10, 20, 40 mg/kg) or metformin (300 mg/kg) for 1, 2 and 4 weeks. Then, metabolic parameters, cardiac sympathovagal balance, LV function, cardiac mitochondrial function, oxidative stress, inflammation, apoptosis, necroptosis, and ferroptosis were determined. All prediabetic rats exhibited cardiac sympathovagal imbalance, LV dysfunction, and cardiac mitochondrial dysfunction. All doses of L6H21 treatment for 2- and 4-weeks attenuated insulin resistance. L6H21 at 40 mg/kg attenuated cardiac autonomic imbalance and LV dysfunction after 1 week of treatment. Both 10 and 20 mg/kg of L6H21 required longer treatment duration to show these benefits. Mechanistically, all doses of L6H21 reduced cardiac mitochondrial dysfunction after 1 week of treatment, resulting in alleviated oxidative stress and inflammation. L6H21 also effectively suppressed cardiac apoptosis and ferroptosis, but it did not affect necroptosis in prediabetic rats. L6H21 provided the cardioprotective efficacy in dose- and time-dependent manners in prediabetic rats via reduction in apoptosis and ferroptosis.     

Effect of corticosteroid treatment on cell recovery by lung lavage in acute radiation-induced lung injury

The purpose of this study was to quantitate cell populations recovered by lung lavage up to 6 weeks following thoracic irradiation (24 Gy) as an index of the acute inflammatory response within lung structures. Additionally, rats were treated five times weekly with intraperitoneal saline (0.3 cc) or methylprednisolone (7.5 mg/kg/week). Lung lavage of irradiated rats recovered increased numbers of total cells compared to controls beginning 3 weeks after irradiation (P less than 0.05). The initial increase in number of cells recovered was attributable to an influx of neutrophils (P less than 0.05), and further increases at 4 and 6 weeks were associated with increased numbers of recovered macrophages (P less than 0.05). Lung lavage of steroid-treated rats at 6 weeks after irradiation recovered increased numbers of all cell populations compared to controls (P less than 0.05); however, numbers of recovered total cells, macrophages, neutrophils, and lymphocytes were all significantly decreased compared to saline-treated rats (P less than 0.05). The number of inflammatory cells recovered by lung lavage during acute radiation-induced lung injury is significantly diminished by corticosteroid treatment. Changes in cells recovered by lung lavage can also be correlated with alteration in body weight and respiration rate subsequent to treatment with thoracic irradiation and/or corticosteroids.     

早期戒烟大鼠肺病理及炎性介质变化

目的观察早期戒烟后大鼠肺组织病理及炎性介质表达变化规律。方法选用Wistar雄性大鼠80只,随机分为对照组及早期戒烟后0天、1周、2周、4周、6周、8周、12周组。采用酶联免疫吸附方法测定各组大鼠血清中IL-8的蛋白质含量,S-P免疫组化学方法检测肺组织NF-κB p65的表达,并光镜下观察HE染色切片、对大鼠气道炎症进行病理学评分。结果早期戒烟组大鼠可见气道上皮细胞纤毛发生粘连、倒伏,上皮细胞空泡变形、坏死、增生,炎症细胞浸润;其血清IL-8浓度、肺组织NF-κB的表达及气道炎症病理评分在戒烟后各时相点较未吸烟对照组明显升高,有统计学意义（P〈0.05）。早期戒烟组大鼠血清IL-8的浓度、肺组织NF-κB的表达及肺组织病理炎症评分在戒烟后略有上升、且在戒烟后8周达到高峰,但随后在戒烟12周时可见IL-8的浓度有下降趋势,肺组织病理炎症反应有所减轻。结论早期戒烟大鼠在戒烟早期虽可见炎症反应略有加重,但随戒烟时间延长,仍可见炎症反应有所减轻。因此,提倡及早且坚持戒烟。     

Particulate matter exposure induces persistent lung inflammation and endothelial dysfunction

Epidemiologic and animal studies have shown that exposure to particulate matter air pollution (PM) is a risk factor for the development of atherosclerosis. Whether PM-induced lung and systemic inflammation is involved in this process is not clear. We hypothesized that PM exposure causes lung and systemic inflammation, which in turn leads to vascular endothelial dysfunction, a key step in the initiation and progression of atherosclerosis. New Zealand White rabbits were exposed for 5 days (acute, total dose 8 mg) and 4 wk (chronic, total dose 16 mg) to either PM smaller than 10 mum (PM(10)) or saline intratracheally. Lung inflammation was quantified by morphometry; systemic inflammation was assessed by white blood cell and platelet counts and serum interleukin (IL)-6, nitric oxide, and endothelin levels. Endothelial dysfunction was assessed by vascular response to acetylcholine (ACh) and sodium nitroprusside (SNP). PM(10) exposure increased lung macrophages (P<0.02), macrophages containing particles (P<0.001), and activated macrophages (P<0.006). PM(10) increased serum IL-6 levels in the first 2 wk of exposure (P<0.05) but not in weeks 3 or 4. PM(10) exposure reduced ACh-related relaxation of the carotid artery with both acute and chronic exposure, with no effect on SNP-induced vasodilatation. Serum IL-6 levels correlated with macrophages containing particles (P=0.043) and ACh-induced vasodilatation (P=0.014 at week 1, P=0.021 at week 2). Exposure to PM(10) caused lung and systemic inflammation that were both associated with vascular endothelial dysfunction. This suggests that PM-induced lung and systemic inflammatory responses contribute to the adverse vascular events associated with exposure to air pollution.