Experimental Study Of Lung Cancer Induced By Coal Tar Pitch And The Inhibition Effects Of Vinegar For Mice

OBJECTIVESTo explore the antitumor effects of vinegar by inhalation, an experimental study of lung cancer induced by the inhalation of coal tar pitch (CTP) aerosol and the inhibition effects of vinegar vapor through inhalation was conducted. A series of studies of lung cancer incidence rate , histopathology and the lymphocyte immune response in peripheral blood of mice was conducted, which provided a basis for the protection of high-risk groups for cancer, and some information for the prevention, therapy and the mechanism research of occupational lung cancer.METHODS1. Experimental models140 Kunming male mice were randomly divided into four groups. group II, III, IV were the experimental groups(each were 40); the control group (group I), a total of 20. Mice of the experimental groups were exposed in whole body inhalation exposure cabinet to coal tar pitch aerosol (165.5mg/m3)for 2 hours. The control group was put into a clean cabinet at the same time. Then mice of groupâ…¢andâ…£were exposed in whole body inhalation sealed clean cabinet to the atomized vapor vinegar and water respectively for another 2 hours, group II keeping in another clean cabinet at the same time 6 days per week for 4 months. All the mice were rearing for another 5 months after the exposure.2. Determination indicators of animalsAnimals were observed twice a day. The growth, diet, activity were recorded. Mice were weighed periodically throughout the study. At the 180th day, 7 mice were randomly selected and the remaining mice were killed at the 270th day in each group respectively. A complete necropsy was performed on all mice and all the gross lesions were recorded. Lungs were removed from the thorax en bloc, weighed; the spleens, too. The weight coefficients of the lungs and the spleens were calculated. The lungs of all animals were then processed for histological examination and paraffin-embedded, stained with hematoxylin and eosin , the incidence of lung cancer and the local pathological changes was observed by microscopy. T lymphocytes of CD4+, CD8+ subtypes of peripheral blood were evaluated by flow cytometry.3. Statistical analysisStatistical analysis of the results was performed using statistical package for social science v13.0; the minimum criterion for statistical significance was set at P = 0.05.RESULTS1. Early in the coal tar pitch aerosol inhalation, part of mice coughed irritability performance. Diet and weight of all the mice was normal, comparing with the control group (P>0.05). But in the later period, the weight of the experimental group declined. The mice natural death and dying later transferred skinny, most of them were suffering from lung cancer or infection.The results showed that the weight coefficients of the lungs were increased in experimental group which no lung tumor-bearing mice ,there was statistical significance comparing with group I (P <0.01). The weight coefficients of the lungs of group III were lower than II and IV and there was no statistical significance between group II, III and IV(P> 0.05).2. Incidence of lung cancerMost of the single tumors lied in the peripheral of the lung; only a few in both the peripheral and the central lobe. The tumor was round, gray translucent, with clear boundaries around. The size was differential ,it could be divided into the military , nodular and mixed type according to the size. Lung cancer occurred seldom, only one mouse was found respectively in group II, III in the sixth month. In the first nine months of exposure, the incidence of lung cancer increased in a large extent which the total incidence was 40.57% (43/106). There was no lung cancer in the control group. Lung cancer occurred 18,9 and 16 mice respectively in group II, III and IV. The incidence rates were 58.06%(18/31),28.13%(9/32) and 53.33% (16/30), there was statistical significance comparing with the control group (P<0.001). The lung cancer incidence of group III was lower than the group II, IV (P <0.05),however, there was no statistical significance compared group II with IV (P >0.05).There were three histological types of lung cancer, namely adenocarcinoma (including bronchioloalveolar carcinoma). Squamous cell carcinoma and carcinoid. The major was adenocarcinoma.3. Immune FunctionFrom the results ,we can see that the weight coefficients of the spleens of group I was the highest, while the group IV was the lowest. But there was no statistical significance of the weight coefficients of the spleens among groups (P> 0.05).The results showed that the percentage of peripheral blood T-Lymphocyte subsets of CD3+, CD4+, ratios of CD4+/CD8+ in group II, III, IV was significantly lower than group I (P <0.01); while the CD8+ increased (P <0.05). There was no statistical significance for the percentage of CD3+, CD4+, CD8+ between group II and group IV (P> 0.05). The percentage of CD3+, CD4+, CD8+ for group III was higher than group II (P <0.05), but there was no statistical significance between group III and group IV (P> 0.05). See Tab. 6.CONCLUSIONS1. Coal tar pitch is a strong carcinogenic substance under high temperature which can induce lung cancer for mice.2. Coal tar pitch can increase the weight coefficients of the lungs for the mice which has pulmonary toxicity and certain damage for the lung.3. Lung cancer induced by coal tar pitch aerosol could be reduced through the inhalation of vinegar vapor for mice.4. The changes of T lymphocytes CD3+, CD4+ subsets and the ratios of CD4+/CD8+ show that the inhalation of a proper concentration of vinegar vapor may reduces the decreasing of the cellular immune function during the exposure of coal tar pitch aerosol for mouse.