Interleukin-6 and Transforming Growth Factor-β1 Control Expression of Cathepsins B and L in Human Lung Epithelial Cells

Abstract

Cathepsins B and L are commonly expressed cysteine proteinases that play a major role in lysosomal bulk proteolysis, protein processing, matrix degradation, and tissue remodeling. Cathepsins are also implicated in tumor progression and metastasis, tissue injury, and inflammation. Cells at sites of inflammation often show upregulation and secretion of cathepsins. The regulation of cathepsin expression by inflammatory mediators is not well understood. The aims of this study were to investigate the effect of the cytokines interleukin-1 beta (IL-1 beta), IL-6, IL-10, transforming growth factor-beta 1 (TGF-beta 1), and hepatocyte growth factor (HGF) on expression of cathepsin B and cathepsin L mRNA (quantitative RT-PCR), on protein expression (ELISA, Western blot), and also on enzymatic activity of cathepsins B and L. Investigations were performed using the human lung epithelial cell line A-549. IL-6 was found to induce a concentration-dependent increase in mRNA expression, protein concentration, and enzymatic activity of cathepsin L. Cathepsin B mRNA and protein expression were not affected by IL-6. In contrast, TGF-beta 1 decreased the amount of cathepsin L mRNA and cathepsin B mRNA. At protein level, it was shown that TGF-beta 1 clearly reduced the concentration of cathepsin L but not cathepsin B. The cytokines IL-1 beta, IL-10, and HGF were found to exert no effect on cathepsin B and L expression. In conclusion, these results are the first to show that IL-6 and TGF-beta 1 have opposite effects on the regulation of expression of cathepsins B and L in A-549 human lung epithelial cells. The proinflammatory cytokine IL-6 induced an upregulation of cathepsin L, whereas TGF-beta 1 suppressed cathepsin B and L expression. Further studies are needed to clarify the mechanism that affects cathepsin B and L expression.

Effect of IL-6 on IGF Binding Protein-3: A Study in IL-6 Transgenic Mice and in Patients with Systemic Juvenile Idiopathic Arthritis

“…On the other hand, in this study we show that both the NSE/hIL-6 transgenic mice and patients with s-JIA have increased proteolysis of serum IGFBP-3, suggesting that the IL-6 induced decrease in intact IGFBP-3 levels is, at least in part secondary to IGFBP-3 proteolysis. In this respect it is noteworthy that IL-6 have been shown to induce production of several proteases including cathepsin B and L (38,39) and, more interestingly, of MMP from a variety of cell types (40 -43). It is noteworthy that the serum IGFBP-3 proteolytic activity is inhibitable by aprotinin and EDTA, a pattern consistent with metal-dependent proteases, and that gelatin zymography of serum of NSE/hIL-6 mice showed the presence of MMP-2.…”

Regulation of TGF-β1-driven Differentiation of Human Lung Fibroblasts

“…Also Brömme and co-workers (26) observed that druginduced overexpression of Cats K and L might be beneficial in the therapy of lung fibrosis. Moreover TGF-␤1 down-regulates both Cat K expression in fibroblasts favoring silica-induced lung fibrosis (27) and Cat L expression in lung epithelial cells (28). However, whether human Cats may directly drive lung fibroblast differentiation or whether modulation of proteolytic activities by their natural inhibitors may affect their fibrogenic potential has not been specifically addressed to date.…”

Proteasome inhibitors modulate chemokine production in lung epithelial and monocytic cells

“…The PCR reaction was optimised with the following primer pairs (59-39): IL-8 sense ATG ACT TCC AAG CTG GCC GTG, IL-8 antisense TCT CAG CCC TCT TCA AAA ACT TCT, b-actin sense TGA CGG GGT CAC CCA CAC TGT GCC CAT CTA, and b-actin antisense CTA GAA GCA TTT GCG GTG GAC GAT GGA GGG. DNA amplification using LightCycler (Idaho Technologies, Idaho Falls, ID, USA), verification of product specificity, and calculation of mRNA concentration were performed as previously described [14].…”