Serum levels of soluble Fas ligand in patients with silicosis

Abstract

Certain patients with silicosis have been reported to exhibit immunological abnormalities such as the appearance of antinuclear antibodies and the occurrence of autoimmune diseases. Fas ligand (FasL) is a type II membrane protein which induces apoptosis by binding to its membrane receptor, Fas. FasL is converted to a soluble form by a metalloproteinase-like enzyme. We have already found serum soluble Fas (sFas) levels in silicosis patients as well as in patients with systemic lupus erythematosus (SLE) to be significantly higher than those in healthy volunteers. To examine further the role of the Fas/FasL system in silica-induced immunological abnormalities, we investigated serum soluble FasL (sFasL) levels in silicosis patients with no clinical symptoms of autoimmune diseases, using ELISA for sFasL. Although the serum sFasL levels in patients with SLE were significantly higher than those in healthy volunteers and showed a slight positive correlation with serum sFas levels, those in silicosis patients exhibited no significant difference from those in healthy volunteers, and there was no correlation with serum sFas levels. However, sFasL levels were elevated in silicosis patients with slight dyspnoea or normal PCO2 among various clinical parameters of silicosis. It may be speculated that the immunological disturbances presented by the abnormalities of apoptosis-related molecules in silicosis patients do not occur with a similar degree of respiratory involvement. Further studies are required to clarify which kinds of factors are involved in silicosis patients who exhibit immunological abnormalities.

Dysregulation of the immune system caused by silica and asbestos

“…than in healthy donors (HDs), although the level of serum soluble Fas ligand did not differ between SPs and HDs (Tomokuni et al, 1997(Tomokuni et al, , 1999. The mean fluorescent intensity (MFI) of membrane 4.…”

Serum neopterin in workers exposed to inorganic dust containing free crystalline silicon dioxide

“…The causes of the fibrogenic effect of free crystalline SiO 2 are not completely clarified [5][6][7][15][16][17][18]. Disbalance in the immune response regulation is suggested [8][9][10][11][12][13].…”

Detection of anti-topoisomerase I autoantibody in patients with silicosis

“…We found that dysregulation of the Fas-mediated apoptotic pathway might play an important role in the pathogenesis of the immunological abnormalities found in silicosis patients 7,8,[17][18][19] . Therefore, it is suggested that the genesis of anti-topo I autoantibodies is associated with the abnormalities of apoptosis-related molecules in silicosis patients.…”

“…Details of materials and methods for B (i), (iii), (iv) and (v) and B (vi) were previously reported by Tomokuni et al 7,17) and Otsuki et al 8) , respectively.…”