Study on the lung histo-pathological changes and interleukin in BALF of silica exposed rats

Objective To observe the changes of interleukin-1(IL-1),interleukin-6(IL-6),and interleukin-16(IL-16) in bronchoalveolar lavage fluid(BALF),the pathological changes of lung tissue in the early stage of silica-exposed rats and to explore their correlations.Methods 168 Wistar rats used were randomly divided into four groups with 42 in each group,i.e.control group,low-,medium-and high-dose groups with silica exposure doses of 15,30 and 60 mg/ml,respectively.Silicotic rats were established by a single intratracheal instillation of silica.The rats in each group were sacrificed and BALFs were collected by the method of time-sharing and segmenting,meanwhile the pathological changes of lung tissue were observed by optical microscope.The levels of interleukin(IL-1,IL-6 and IL-16) were determined by enzyme-linked immunosorbent assay(ELLSA).Results The levels of IL-1,IL-6 and IL-16 in BALF were affected significantly by the time of silica exposure and the doses of silica(P0.05 and P0.01).More obvious changes were observed in the high-dose group compared to the control group.IL-l levels at the 1st,3rd,7th,14th,21st and 28th d were(133.55±27.0),(154.50±42.11),(136.43±54.71),(198.0±35.5),(103.38±8.9) and(127.50±31.9) nmol/L respectively,which were significantly higher than that of the control group(P0.05).IL-6 levels at the 1st,3rd,7th,14th,21st and 28th d were(106.99±25.6),(83.66±12.1),(99.25±31.1),(149.90±33.2),(114.88±32.1) and(131.87±48.1)nmol/L respectively,which were also significantly different in comparison with the control group(P0.05).IL-l6 levels at the 1st,3rd,7th,14th,21st and 28th d were(1.95±0.47),(2.30±0.65),(2.20±0.74),(3.14±0.45),(2.14±0.60) and(2.67±0.76) nmol/L,which were significantly different in comparison with the control group(P0.05).The peak of IL-1,IL-6 and IL-16 levels reached at the 14th d,which was consistent with the pathological changes.Conclusions The content changes of IL-1,IL-6 and IL-16 levels in BALF are closely related to the development of free silica-induced pulmonary fibrosis in rats exposed to silica.