Annals of Occupational and Environmental Medicine

Original Article

Identification of Cross-linked 46 KDa Protein in Experimentally Induced Silicotic Nodule in Rat Lung: You Mie Kim, Young Jin Kim, Soo Young Lee; Korean Journal of Occupational and Environmental Medicine 2003;15(2):181-187. Published online June 30, 2003; DOI: https://doi.org/10.35371/kjoem.2003.15.2.181

Abstract PDF: OBJECTIVES
This study was conducted in order to understand the cellular events associated with silica-induced pathogenesis of the rat lung.
METHODS
Silicosis was induced by an intratracheal instillation of 50 mg of silica (SiO2, 0.15 - 10 micrometer) suspended in 500 microliter of a sterile saline solution in Sprague-Dawley rats weighing 200g. Silicotic nodules were excised from the rat lungs 4 weeks after silica instillation, then boiled for 4 days at 110 degrees in solution containing 2% SDS, 10 M urea and 40 mM DTT. The insoluble cellular encapsulates were electrophoresed on 4-12 % gradient SDS-PAGE, and the amino acid composition was analyzed. Affinity chromatographies of the homogenate supernatants of the control lung, silicotic nodule, and normal rat plasma were performed using rabbit IgG, anti-rat, cross-linked protein from the silicotic nodule. The amounts of N epsilon-(gamma-glutamyl) lysine cross-linked in the control lungs and silicotic nodules were determined using HPLC analysis.
RESULTS
The remaining cross-linked protein was insoluble in the 10 M urea and 40 mM sulfhydryl reagents even under prolonged boiling conditions. The encapsulate revealed the retention of silica particles within the protein whose amino acid composition showed a high percentage of alanine, leucine and glycine. A 46 KDa protein was identified as a cross-linked protein in the silicotic nodule by affinity chromatography. The level of N epsilon-(gamma-glutamyl) lysine dipeptide in the nodule digest was prominently increased compared with that in the control lung.
CONCLUSIONS
Transglutaminase (TGase)-catalyzed cross-linking appears to be involved in the silicotic nodule formation, and the 46 KDa protein may be cross-linked to itself and other extracellular matrix proteins during fibrosis and the formation of eventually insoluble nodule.

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Original Article

Identification of Plasma Coagulation Factor XIII, Transglutaminase 3 and N epsilon-(gamma-glutamyl) lysine cross-Link in the Silicotic Nodule by Immunohistochemistry: You Mie Kim, Young Jin Kim, Soo Young Lee; Korean Journal of Occupational and Environmental Medicine 2003;15(2):173-180. Published online June 30, 2003; DOI: https://doi.org/10.35371/kjoem.2003.15.2.173

Abstract PDF: OBJECTIVES
This study was performed to examine the immunohistochemical distribution of TGase 1, 2, 3, coagulation factor XIII and N epsilon-(gamma-glutamyl) lysine cross-link in the silicotic nodules formed after an intratracheal instillation of the silica.
METHODS
The immunohistochemical examinations used antibodies against TGase 1, 2, 3, coagulation factor XIII and N epsilon-(gamma-glutamyl) lysine isopeptide in the silicotic nodules induced after an intratracheal instillation of 50 mg of size fractionated, crystalline silica.
RESULTS
A high level of TGase 3 was related to the severity of fibrosis in silicotic nodules and extracellular coagulation factor XIII was detected around the nodules. Expressions of both membrane-bound TGase 1 and TGase 2 were barely detected in the nodules although high expressions were detected in the intact lung. Formation of N epsilon-(gamma-glutamyl) lysine cross-links was increased in severe fibrotic nodules.
CONCLUSIONS
TGase 3 might contribute to the eventual stone-like fibrosis via formation of N epsilon-(gamma-glutamyl) lysine cross-links. Futhermore, coagulation factor XIII plays a role in the formation of a provisional matrix which results in fibrogenesis during silicotic nodule formation.

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