Synchrotron microradiography study on acute lung injury of mouse caused by PM2.5 aerosols

https://doi.org/10.1016/j.ejrad.2005.11.035Get rights and content

Abstract

In order to investigate FeSO4, ZnSO4 (the two of main metal compositions of Shanghai PM2.5 (particle matter with those aerodynamical diameter <2.5 μm)) effects on acute lung injury, six solutions contained PM2.5 aerosol particles, FeSO4, ZnSO4 and their mixtures were instilled intratracheally into mouse lungs for experiment. By 2 days after instillation, the live mice were checked in vivo by synchrotron refractive index microradiography. In addition after extracted and examined by dissection, the right lobes of lung were fixed by formalin, then imaged by synchrotron microradiography again. Corresponding parts of those lung tissues were embedded in paraffin for histopathologic study. The synchrotron X-ray microradiographs of live mouse lung showed different lung texture changes after instilled with different toxic solutions. Hemorrhage points in lung were observed more from those mice instilled by FeSO4 contained toxin solutions groups. Bronchial epithelial hyperplasia can be observed in ZnSO4 contained solution-instilled groups from histopathologic analysis. It was found that the acute lung injury of mice caused by solution of PM2.5 + FeSO4 + ZnSO4 was more serious than other toxin solutions. Results suggested that FeSO4 mainly induced hemorrhage and ZnSO4 mainly induced inflammation and bronchiolar epithelial hyperplasia in the early toxicological effects of PM2.5.

Introduction

The increasing mortality and morbidity due to cardiopulmonary complications are attributed to elevated concentration levels of ambient particulate matters, in particular, of small inhalable particles [1]. Therefore, it is essential to understand in detail the mortality mechanism induced by such fine particles. Many reports suggest that PM2.5 induce reactive oxygen species (ROS) and inflammatory mediators, resulting in vascular permeability changes, airway constriction and tissue injury [2], [3]. The transition metal ions and peroxides in aerosols can induce free radicals and cause both cytotoxicity and a strong oxidation response [4]. Based on the previous report [5], it is found that the main acute effects of PM are due to soluble ions. Shanghai as one of most quickly developing cities in the world in economics, its energy exhausts are also raised quickly. The Chinese biggest iron plant—Baoshan steel plant and electronic power plants make two of the main contributions to PM2.5 in Shanghai. Fe and Zn are the two main transition elements in PM2.5 and high SO2 (from coal burning) even make those aerosols more toxic to our health [3]. Those soluble metal constituents of residual oil fly ash (ROFA) particles can enhance the sensitization of lung injury [6]. As PM2.5 collected from the industrial city—Shanghai contains relatively higher transition elements for instance, Fe, Zn, etc. [7], and higher sulfates [8], it is important to study the effects of the main transition compositions FeSO4 and ZnSO4 in PM2.5 induced acute pneumonia process.

Many studies related to pneumonia and cytotoxicity were carried out on the histopathological examination of lung section [9], [10], [11]. Usually, in those previous work of toxicological studies on tissues, performed by optical microscopy and the scanning proton microprobe [7], only thin tissue samples (<50 μm) excised from killed rats [10], [12] were used on some respiratory function tests [13] and on analyzing the structural changes [10]. Our present work proves that such critical limitation can be lifted by using edge-enhanced microradiographs with high energy of X-rays which can penetrate a mouse. The high intensity of X-rays makes it possible to achieve high resolution in a short time, for instance, 3 ms or less, as what required for imaging a live mouse without observed damage [14], [15]. Here, it is important to use this method in vivo to monitor acute pulmonary toxicity after the mouse intratracheally instilled as the PM2.5 toxic effect is a developing process [16]. Combining those studied results of the transition element Fe, Zn effects on lung epithelial cultured cells [17] with this studying result on lung tissue structure, it may understand more about Fe, Zn toxic effects in the industrial city PM2.5.

Section snippets

Aerosols sampling

PM2.5 samples were collected by a stacked filter air sampler at the Baoshan area which is one of the industrial districts in Shanghai. The PM2.5 aerosols were collected on Teflon filters at 6.5 m above ground at a flow rate of 78 l/min. Each sample required ∼360 h by a middle flux air sampler and all aerosol samples were collected during the period of September–November 2003.

Elemental analysis

The elemental analysis for PM2.5 was carried out by a VG X7 ICP-MS instrument (Thermo electron corporation) and at least 16

Elemental contents of PM2.5

The PM2.5 solution used for instillation was analyzed, as already mentioned, by X7 ICP-MS. The results are shown in Table 1. It is clear that the concentration of transition elements (Fe, Zn) is much higher than others (Cr, Ni, Cu, Pb, etc.). It can also be found that higher S in Shanghai PM2.5. Furthermore, Fe sulfate is one of main compositions in Fe contained PM2.5 in the previous studies [8], [20]. The higher content of transition metal Fe, Zn sulfates in Shanghai PM2.5 may be play

Conclusion

In conclusion, the synchrotron X-ray microradiographs observed in vivo show much high resolution which can monitor mouse hemorrhage process. By that un-uniformity of appearance of lung texture and hemorrhage spots with a size of <0.5 mm can be found for groups exposed to toxin solutions but not in saline solution. The hemorrhage spots and hemorrhage lines appeared in the group of mice instilled by solution of PM2.5 + FeSO4 + ZnSO4 were more than the ones in other groups of mice. FeSO4 induced more

Acknowledgements

This work was supported by grants from Shanghai Nature Science Foundation of China (03ZR14111), a Major Project of Knowledge Innovation Program of Chinese Academy of Sciences (Contract No. KJCXZ-SW-No1) and a Major Project of the National Natural Science Foundation of China (Grant No. 10496182).

References (28)

  • Y. Tong et al.

    A study on the elemental distribution change in lung tissue of pneumonia mouse caused by aerosol of PM10

    Trace Elem Electrolytes

    (2002)
  • G. Fang et al.

    Review of atmospheric water-soluble ionic species in Asia during 1998–2001

    Toxicol Ind Health

    (2005)
  • J.A. Dye et al.

    Acute pulmonary toxicity of particulate matter filter extracts in rats: conherence with epidemiologic studies in Utah valley residents

    Environ Health Perspect

    (2001)
  • K.J. Nikula et al.

    Influence of exposure concentration or DOSE on the distribution of particulate material in rat and human lungs

    Environ Health Perspect

    (2001)
  • Cited by (19)

    • Performance evaluation of surgical, N95 and FFP2 respiratory masks by manikin-based sampling system for assessing the protection against airborne dust

      2022, Atmospheric Pollution Research
      Citation Excerpt :

      Regarding the severity and frequency of dusty air pollution in Iran as well as in Kermanshah province, people are forced to use available respiratory masks. Various respiratory masks are available with different filters for personal protection, which are made for hospital applications and gaseous or particulate contaminants control (Brosseau et al., 1989; Tong et al., 2006). The most common respiratory masks used by people are surgical, N95, and FFP2 valves masks that each of them has its own characteristic and performance.

    • Inhibitory functions of cardamonin against particulate matter-induced lung injury through TLR2,4-mTOR-autophagy pathways

      2020, Fitoterapia
      Citation Excerpt :

      PM2.5 is made up of a number of different components that exert toxic effects, including polycyclic aromatic hydrocarbons, oxygenated volatile organic compounds, and heavy metals [4,5]. The relationship between PM2.5 and inflammation has been identified as playing a role in many pulmonary diseases, such as acute lung injury, asthma, and chronic obstructive pulmonary disease, while PM2.5-induced inflammation is associated with the release of numerous cytokines and chemokines, such as interleukins (ILs) and tumor necrosis factor (TNF)-α [6–8]. Because there is a significant positive correlation between PM2.5 exposure and the risk of asthma and lung cancer incidence and mortality [9], there is an urgent need to develop new prevention and treatment strategies for respiratory diseases.

    • Formulation and role of polymeric and inorganic nanoparticles in respiratory diseases

      2020, Targeting Chronic Inflammatory Lung Diseases Using Advanced Drug Delivery Systems
    • Toxicological study of injuries of rat's hippocampus after lead poisoning by synchrotron microradiography and elemental mapping

      2010, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
    • Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

      2008, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
    • Suppression of zinc-induced p53 phosphorylation and p21 expression by wortmannin in A549 human pulmonary epithelial cells

      2008, Environmental Toxicology and Pharmacology
      Citation Excerpt :

      Excess exposure to zinc is a hazard for industrial workers, especially through inhalation of welding fumes and exposure in smelting operations (Walsh et al., 1994). It has been reported that twice instillations of zinc sulfate (ZnSO4) solution (15 mg/ml) into mouse lungs induced acute lung injury such as inflammation and bronchial epithelial hyperplasia (Tong et al., 2006). In addition, treatment with ZnSO4 induced cellular damage in A549 human pulmonary epithelial cell line with an ED50 of 250 μM (Riley et al., 2005).

    View all citing articles on Scopus
    View full text