Investigation On Silicon Levels In Vivo And Its’ Relationship With TGF-β1and TNF-α In Workers Exposed To Silica

Objectives In the study we detected serum silicon, urine silicon in workers byinductively coupled plasma mass spectrometry (ICP-MS) and combined with the serumlevel of transforming growth factor-β1(TGF-β1), tumor necrosis factor-α (TNF-α) toinvestigate the meaning and values of silicon as a biomarker in the early diagnosis andpathogenesis of silicosis.Methods1The recruited subjects: workers exposed to silicious dust more than1years ina iron mine were selected as our silica exposure group (n=736), those who quited formdust exposed for more than1years as our escaped group (n=24), staff without silicaexposure served as our control group (n=120), diagnosed silicosis patients served as ourpatient group (n=38), and other patients who had not yet been diagnosed with silicosisserved as observing group (n=9). All the people come from the same iron mine.2Epidemiological surveys: Self-made questionnaire was used to collect generalinformation on all subjects including age, gender, smoking, alcohol consumption,smoking history, past medical history, occupational protection and so on.3Biologicalsample collection: EP tube anticoagulants was used to collect the blood samples(workersexposed to silica138cases, healthy people41cases, silicosis patients112cases).15mlcentrifugal tube was prepared for collecting the urine samples. All samples were stored in-20℃refrigerator.4Serum silicon, urine silicon in vivo were detected by inductivelycoupled plasma mass spectrometry (ICP-MS); Serum transforming growth factor-β1(TGF-β1), tumor necrosis factor-α (TNF-α) in each group were determined with ELISA.5Statistical analysis：All data were showed as x s. The statistics methods includeANOVA, t test and person correlation. P<0.05was considered statistically significant.Results1The RSD of serum silicon level detected by ICP-MS for5times is1.73~5.93%,and the standard addition recovery rate ranges88.7~109.7%; The RSD of urine siliconlevel ranges1.15~4.29%, and the standard addition recovery rate ranges88.3~115.3%.2The serum silicon level in silica exposure group and observing group were significantlyincreased than that of control group (P<0.05). The serum silicon level in silicosis groupwas not significantly increased than that of control group (P>0.05).3The urine siliconlevel in workers exposed to silica was significantly increased than that of control groupand silicosis group (P<0.05).4Along with extended time exposed to silica, the serum and urine silicon level in exposed workers appeared a rapidly increasing trend, andreached the peak in1~5years, and then gradual decline after that.5The silicon level indifferent type of exposed workers silica is different, and the same as urine silicon. Butamong these the silicon level in blasting workers and the drilling workers were higherthan other workers.6The level of serum silicon and urine silicon in escaped group werelower than that of exposed group (P<0.05).7TGF-β1, TNF-α content in exposed group,observing group and silicosis group were higher than that of control group (P<0.05).With the process of silicosis, TGF-β1and TNF-α content gradually increased (P<0.05).The results of correlation analysis on the case group (observation group and silicosisgroup) showed serum silicon and TGF-β1, TNF-α content existed negative correlation(r1=-0.682, r2=-0.651), urine silicon level and TGF-β1, TNF-α content existed negativecorrelation r1=-0.697, r2=-0.724).8TGF-β1, TNF-α content in groups exposed to silicamore than5years were higher than that of control group and those exposed to silica lessthan5years(P <0.05).9In groups exposed to silica less than5years, serum silicon andTGF-β1, TNF-α content existed positive correlation (r1=0.689, r2=0.614), urine siliconlevel and TGF-β1, TNF-α content existed positive correlation(r1=0.672, r2=0.589). Ingroups exposed to silica more than5years, serum silicon and TGF-β1, TNF-α contentexisted negative correlation (r1=-0.792, r2=-0.706), urine silicon level and TGF-β1,TNF-α content existed negative correlation (r1=-0.733, r2=-0.624).10Workers exposedto dust less than10years divided into subgroups by2years limit, the levels of serumsilicon, urine silicon and TGF-β1, TNF-α were significantly higher than that of controlgroup respectively from2~，0~，6~，8~years.Conclusions The level of silicon in workers was rapidly increased after exposed tosilica and the change was prior to the expression of TGF-β1and TNF-α, which indicatedthat determining the level of silicon in vivo might be of some value and meaningful in thediagnosis and pathogenesis of silicosis.