ABSTRACT
Respiratory tract disease represents the most important group of occupational disease in the cement industry. Inhalation of silica dust leads to silicosis, the alveolar macrophage plays a key role in the onset and development of inflammatory and fibrogenic lung disease through their ability to release potent inflammatory and fibrogenic mediators. The present study aimed to measure the levels of TNF-alpha and IL-6, in order to determine a possible relationship between the presence of silica particles, cytokine production, and pulmonary dysfunction in workers exposed to cement dust for less and more than 10 years. Also, to test the hypothesis that silica-induced apoptosis of human AM may involve the activation of ICE, we determine the activity of caspase-3 in these workers. The correlations between these previously mentioned bioindices and pulmonary function tests were investigated. . The study consisted of forty male patients workers engaged in cement production and a control group of 40 normal healthy males. The exposed workers were divided according to the duration of the exposure time into two groups: 22 workers were exposed to cement dusts for less than I0 years and 18 workers for more than 10 years
Determination of TNF-alpha and IL-6 in plasma of exposed workers enzyme linked immunosorbant assay [ELISA] and caspase-3 activity in white blood cells of exposed workers by colorimetric methods. The results of the current study showed that pulmonary function tests were significantly lower in exposed workers for more than 10 years than those with less than 10 years. Moreover; in exposed workers for more than I0 years, the plasma levels of TNF-alpha and IL-6 were significantly increased compared to those revels in exposed workers to cement dusts for less than I0 years [P<0.001 for each]. Besides, in this group of workers, caspase-3 activity levels were significantly higher than that of controls [P < 0.001]. However, there was no significant difference in caspme-3 activity levels between both groups of workers. Significant correlations were also found between TNF-alpha IL-6, caspase-3 activity levels and pulmonary function tests. In conclusion, the results of the present study showed that prolonged exposure to silica stimulates AM to produce significant increased levels of TNF-alpha and IL-6 compared to those of controls. Moreover, increased caspase-3 activity was also observed in exposed workers. These changes were associated with a significant reduction in pulmonary functions of these workers