Evaluation of tumor necrosis factor-alpha (TNF) as an exposure or risk marker in three French coal mining regions

Several studies have shown the crucial role of the tumor necrosis factor-alpha (TNF) in the fibrosis induced by dusts containing silica and its role in the transition from simple pneumoconiosis (CWSP) to progressive massive fibrosis (PMF). To evaluate the nocivity of dust exposure among coal miners (n = 474) from different mining regions in France (e.g., Nord-Pas de Calais, Lorraine, and Provence), spontaneous and LPS or silica-induced TNF released by peripheral blood monocytes was quantified. The primary aim of this effort was to study the link between the prevalence of coal workers pneumoconiosis (CWP) and TNF release. TNF levels were significantly different between active miners from the three regions. However, after correction for age and region, TNF was found not to be related to dust exposure. Interestingly, a very low, homogeneous expression of TNF was observed in the group from Provence. These results are probably related to the absence of pneumoconiosis in this area. A positive relation between profusion and TNF release was found for all stimulants among retired miners with PMF. Although in retired miners TNF release was consistently higher, the design of the study does not allow this effect to be separated from that of age. Both silica and nonstimulated TNF release were found to increase with increasing radiological symptoms; the opposite was found for LPS-induced release.