Effect Of Sulfur Dioxide Inhalation On The Ultrastructures Of Several Organs And Cytokine Levels Of Mice

Sulfur dioxide (SO₂) is a major air pollutant all over the world. It can cause respiratory tract diseases such as tracheitis, asthma, emphysema, and has close relations with lung cancer. But many studies indicated that SO₂ is a systemic toxin, not only to respiratory system. So we studied the effects of SO₂ in the following aspects:First, in order to elucidate the immunotoxic mechanism exerted by sulfur dioxide (SO₂), we investigated the effect of SO₂ on the cytokine levels in lungs and serum of male mice. Levels of interlukin-6 (IL-6) , tumor necrosis factor-α (TNF-α) , transforming growth factor- β1 (TGF-β1) in lungs and serum from male mice exposed to SO₂ at various concentrations (14, 28 and56mg/m³)were measured by the enzyme-linked immunosorbent assay. The results were as follows: (1) For lung tissues of male mice, expose to SO₂ at 14 mg/m³ caused statistically significant increase of levels of IL-6 and TNF-α (p<0.05) compared with the control group, at 28 mg/m³caused statistically highly significant increase of level of IL-6 (p<0.01) and significant increase of TNF-α (p<0.05), at 56 mg/m³caused no any significant increase of levels of IL-6 and TNF-α. SO₂ at all concentrations tested could not cause significant change of level of TGF-β1 in lungs. (2) For serum from male mice, after expose to SO₂ at 14 mg/m³, level of TNF-α was significantly increased (p<0.05) compared with the control group, but the changes of levels of IL-6 and TGF-β1 were not significant. After expose to SO₂ at 28 mg/m³ and 56 mg/m³ , levels of IL-6 and TNF-a were increased non-significantly, but level of TGF-β1 was decreased non-significantly. These results imply that inflammation reaction could be induced in lung tissue by SO₂ inhalation and the inflammation reaction might relate to these cytokines. And determination of cytokines in lung may be more valuable than in serum when lung injury caused by SO₂.Second, to investigate the effect of sulfur dioxide inhalation on theultrastructure, the ultrastructures of the lungs, livers and spleens in mice were observed with electron microscopy after the mice were treated by SO2 inhalation (28, 56 and 112mg/m3). The results were as follows: (1) It was found that type II alveolar cells of lungs in tested groups had obvious pathological changes including vacuolating of osmiophilic multilamellar bodies, decrease of microvillus , mitochondrial pyknosis or swelling and various changes of nucleus and chromatin. Meanwhile significant changes of mitochondrial and nucleus in type I alveolar cells were also observed. (2) A series of pathological changes were discovered in hepatic cells in tested groups, such as swelling of nucleus, dispersion of fatty droplets, degenerated mitochondria and dilation of rough endoplasmic reticulums etc; for SO2 exposure at 56mg/m3 the ultrastructure also showed necrosis of hepatocytes with unclear karyotheca or nearly dissolved karyotheca and decrease of organelle; for SO2 exposure at 112mg/m3 acid degeneration, fatty degeneration and severe necrosis of hepatocytes were found in addition to above changes. (3) Apoptotic number of splenocytes from mice exposed to SO2 was increased by SO2 inhalation in a dose-dependent manner.Finally, the ultrastructures of the testis, brains, hearts and kidneys in mice were also observed with electron microscopy after the mice were treated by SO2 inhalation (28 and 56 mg/m3). The results were as follows: (1) Compared with control group, the basement membrane, various seminiferous cells, spermatozoa, sertoli cells of testis were changed in both tested groups. The changes of 56mg/m3 group were serious than the 28mg/m3 group. (2)In the tested groups, some of the cerebral cortex neurons, many glialcells and nerve fiber were damaged, Ihere was no significant difference between two tested groups. (3) It was found that mitochondrial swelling, decrease or disappearance of mitochondria crista, myocardial myofibril disorder, various changes of nucleus and chromatin, intercalated discs dissociation, endothelium edema in heart tissues in tested groups. In addition to above changes, myofibrillar fragmentation and dissolution, some myocardial cell membranes breach and inflammatory cell infiltration were observed in the...