Objective To study the expression level and pattern of tumor necrosis factor α(TNF-α)/tumor necrosis factor receptor(TNFR) signaling proteins in apoptosis signal pathway in alveolar macrophage(AM), and investigate the possible role of TNF-α/TNFR signaling proteins in promoting pulmonary fibrosis in coal workers with pneumoconiosis.
Methods Coal workers under observation(n=4) and with Stage I coal workers' pneumoconiosis(CWP) n=24, including 12 cases diagnosed after being removed from dust exposed workstation(RDE) and 12 cases diagnosed during working in dust exposed workstation(DE) were enrolled as study subjects. Large volume pulmonary lavage fluids were collected, isolated, and purified for AM lysis. Western blot was used to detect β-actin, TNF-α, TNFR1, TNFR2, Caspase-8, Caspase-3, nuclear factor kappa B(NF-κB) P65 and P50, using β-actin as reference. Relative expression levels of each signaling protein was analyzed using FlourChem HD2 software.
Results The expression levels of TNF-α, TNFR1, Caspase-8, Caspase-3, NF-κB P65, NF-κB P50, and TNFR2 in the CWP stage I patients were 2.69±1.19, 1.95±1.02, 2.80±1.95, 2.19±1.49, 2.70±1.30, 2.45±1.32, and 5.15±1.24, respectively, higher than those of the observation workers(0.93±0.14, 1.18±0.19, 1.24±0.55, 1.44±1.08, 1.41±0.26, 1.35±0.53, and 1.07±0.08)(P < 0.05). In the DE workers, the expression levels were 3.544±1.2783, 2.508±0.925, 3.274±2.183, 3.079±1.304, 3.332±1.062, 2.865±1.024, and 5.817±1.089, respectively, higher than those of the RDE workers(1.899±1.191, 1.318±0.538, 1.627±0.740, 1.764±0.815, 2.068±0.708, 1.602±0.672, and 4.483±1.425)(P < 0.05).
Conclusion Elevated expression levels of AM apoptosis signaling proteins including Caspase-3, Caspase-8, NF-κB(P65 and P50), TNFR, and TNF-α are detected in CWP patients, and decreased after workers being removed from dust exposed workstation. The TNF-α/TNFR signaling pathway may play a part in pneumoconiosis occurrence.
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