taurochenodeoxycholic-acid and Pulmonary-Fibrosis

Long-term exposure to crystalline silica (CS) results in silicosis, which is characterized by progressive pulmonary fibrosis. The endoplasmic reticulum (ER) plays a critical role in protein processing, and the accumulation of unfolded proteins triggered by external stimuli often leads to ER stress. In the present study, we found that inhibition of ER stress alleviated CS-induced pulmonary fibrosis. Moreover, we observed that TXNDC5, a resident ER protein, was involved in the activation of fibroblasts. Mechanistically, we explored the relationship between ER stress and TXNDC5 and demonstrated that IRE1α-XBP-1 signaling was closely related to TXNDC5. Pharmacological inhibition of IRE1α endoribonuclease activity, in addition to knockdown of Xbp1 expression, reduced TXNDC5 expression in activated fibroblasts. Furthermore, pharmacological inhibition of IRE1α in vivo ameliorated pulmonary function and delayed CS-induced lung fibrosis. In conclusion, the present study illuminates the role of ER stress-related IRE1α-TXNDC5 signaling in fibroblast activation and its effects on CS-induced pulmonary fibrogenesis, which may provide novel targets for silicosis therapy.

Topics: Animals; Cytokines; Endoplasmic Reticulum Stress; Endoribonucleases; Lung; Male; Mice; Mice, Inbred C57BL; NIH 3T3 Cells; Protein Serine-Threonine Kinases; Pulmonary Fibrosis; Silicon Dioxide; Taurochenodeoxycholic Acid; Thioredoxins; Up-Regulation

Several studies demonstrate that endoplasmic reticulum (ER) stress-mediated epithelial-mesenchymal transition (EMT) is involved in the process of bleomycin (BLM)-induced pulmonary fibrosis. Tauroursodeoxycholic acid (TUDCA), a bile acid with chaperone properties, is an inhibitor of ER stress. This study aimed to investigate the preventive effects of TUDCA on BLM-induced EMT and lung fibrosis.. The model of lung fibrosis was established by intratracheal injection with a single dose of BLM (3.0 mg/kg). In TUDCA + BLM group, mice were intraperitoneally injected with TUDCA (250 mg/kg) daily.. BLM-induced alveolar septal destruction and inflammatory cell infiltration were alleviated by TUDCA. BLM-induced interstitial collagen deposition, as determined by Sirius Red staining, was attenuated by TUDCA. BLM-induced elevation of pulmonary α-smooth muscle actin (α-SMA) and reduction of pulmonary E-cadherin were attenuated by TUDCA. BLM-induced pulmonary Smad2/3 phosphorylation was suppressed by TUDCA. BLM-induced elevation of Ki67 and PCNA was inhibited by TUDCA in mice lungs. In addition, BLM-induced elevation of HO-1 (heme oxygenase-1) and 3-NT (3-nitrotyrosine) was alleviated by TUDCA. Finally, BLM-induced upregulation of pulmonary GRP78 and CHOP was attenuated by TUDCA.. These results provide evidence that TUDCA pretreatment inhibits Smad2/3-medited EMT and subsequent lung fibrosis partially through suppressing BLM-induced ER stress and oxidative stress.

Topics: Animals; Bleomycin; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Epithelial-Mesenchymal Transition; Lung; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; Phosphorylation; Pulmonary Fibrosis; Signal Transduction; Taurochenodeoxycholic Acid; Up-Regulation

The purpose of this study was to evaluate the role of CCAAT/enhancer-binding protein homologous protein (CHOP), an important transcription factor that regulates the inflammatory reaction during the endoplasmic reticulum (ER) stress response, in the development of pulmonary fibrosis induced by bleomycin (BLM) in mice. An intratracheal injection of BLM transiently increased the expression of CHOP mRNA and protein in an early phase (days 1 and 3) in mice lungs. BLM-induced pulmonary fibrosis was significantly attenuated in Chop gene deficient (Chop KO) mice, compared with wild-type (WT) mice. Furthermore, the inflammatory reactions evaluated by protein concentration, the total number of leucocytes and neutrophils in the bronchoalveolar lavage fluid (BALF), the mRNA expression of interleukin 1b and caspase 11, and the apoptotic cell death were suppressed in Chop KO mice compared with those in WT mice. In addition, administration of tauroursodeoxycholic acid (TUDCA), a pharmacological agent that can inhibit CHOP expression, inhibited the BLM-induced pulmonary fibrosis and inflammation, and the increase in Chop mRNA expression in WT mice in a dose-dependent manner. These results suggest that the ER stress-induced transcription factor, CHOP, at least in part, plays an important role in the development of BLM-induced pulmonary fibrosis in mice, and that the inhibition of CHOP expression by a pharmacological agent, such as TUDCA, may be a promising strategy for the prevention of pulmonary fibrosis.

Topics: Animals; Apoptosis; Bleomycin; Disease Models, Animal; Endoplasmic Reticulum Stress; Gene Expression; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Pulmonary Fibrosis; RNA, Messenger; Taurochenodeoxycholic Acid; Transcription Factor CHOP

The present study prepared the pulmonary fibrosis model in mice by using Bleomycin and carry out the investigations on the effects of taurochenodeoxycholic acid (TCDCA) in preventing pulmonary fibrosis in mice. Expression profiles of the bile acid receptors in the lung of mice FXRα and TGR5 were examined, and pulmonary coefficient, pathohistology as well as expression of TNF-α, MMP-2, MMP-9 and TIMP-2 in pulmonary fibrosis mice. The results showed that FXRα and TGR5 simultaneously expressed in the lung of the mice; TCDCA in dosages of 0.05 and 0.1g/kg can extremely significantly decrease the pulmonary coefficient in the model mice (P>0.01), TCDCA in a dosage of 0.2g/kg significantly decreased the pulmonary coefficient in the model mice (P<0.05); TCDCA in dosages of 0.05 and 0.1g/kg significantly reduce the pathological damages on their lungs; TCDCA can extremely significantly decrease the expression levels of TNF-α and TIMP-2 in pulmonary tissues in the pulmonary fibrosis mice (P>0.01), the expression level of MMP-9 extremely significantly increased (P>0.01), while it has no significant effects on MMP2. The results as mentioned above indicated that TCDCA had antagonistic actions on pulmonary fibrosis in mice.

Topics: Animals; Female; Lung; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Pulmonary Fibrosis; Receptors, G-Protein-Coupled; Staining and Labeling; Taurochenodeoxycholic Acid; Tumor Necrosis Factor-alpha