Pirfenidone ameliorates silica-induced lung inflammation and fibrosis in mice by inhibiting the secretion of interleukin-17A.

Silicosis is a global occupational disease characterized by lung dysfunction, pulmonary inflammation, and fibrosis, for which there is a lack of effective drugs. Pirfenidone has been shown to exert anti-inflammatory and anti-fibrotic properties in the lung. However, whether and how pirfenidone is effective against silicosis remains unknown. Here, we evaluated the efficacy of pirfenidone in the treatment of early and advanced silicosis in an experimental mouse model and explored its potential pharmacological mechanisms. We found that pirfenidone alleviated silica-induced lung dysfunction, secretion of inflammatory cytokines (TNF-α, IL-1ß, IL-6) and deposition of fibrotic proteins (collagen I and fibronectin) in both early and advanced silicosis models. Moreover, we observed that both 100 and 200 mg/kg pirfenidone can effectively treat early-stage silicosis, while 400 mg/kg was recommended for advanced silicosis. Mechanistically, antibody array and bioinformatic analysis showed that the pathways related to IL-17 secretion, including JAK-STAT pathway, Th17 differentiation, and IL-17 pathway, might be involved in the treatment of silicosis by pirfenidone. Further in vivo experiments confirmed that pirfenidone reduced the production of IL-17A induced by silica exposure via inhibiting STAT3 phosphorylation. Neutralizing IL-17A by anti-IL-17A antibody improved lung function and reduced pulmonary inflammation and fibrosis in silicosis animals. Collectively, our study has demonstrated that pirfenidone effectively ameliorated silica-induced lung dysfunction, pulmonary inflammation and fibrosis in mouse models by inhibiting the secretion of IL-17A.

[Angiotensin II promotes the expression of TXNIP through angiotensin II type 1 receptor in islet ß cells].

This study investigated the effect of angiotensin II (Ang II) on apoptosis and thioredoxin-interacting protein (TXNIP) expression in INS-1 islet cells and the underlying mechanism. INS-1 cells cultured in vitro were treated with different concentration of Ang II for different time, and the viability was measured using cell counting kit-8 (CCK-8). After treatment with 1 × 10-6 mol/L Ang II for 24 h, flow cytometry and Western blot were used to measure the cell apoptosis, and Western blot was used to analyze the protein expression of TXNIP, carbohydrate response element-binding protein (ChREBP) and angiotensin II type 1 receptor (AT1R). Real-time PCR was used to detect TXNIP and ChREBP mRNA expression. IF/ICC was used to observe the TXNIP, ChREBP and AT1R expression. The results showed that Ang II reduced cell viability and induced the expression of TXNIP in a dose- and time-dependent manner (P < 0.05, n = 6) compared with the control group. Ang II induced apoptosis and up-regulated the expression of ChREBP and AT1R (P < 0.05, n = 6). AT1R inhibitor, telmisartan (TM), blocked Ang II-induced TXNIP and ChREBP overexpression (P < 0.05, n = 6) and inhibited Ang II-induced apoptosis. Taken together, Ang II increased ChREBP activation through AT1R, which subsequently increased TXNIP expression and promoted cell apoptosis. These findings suggest a therapeutic potential of targeting TXNIP in preventing Ang II-induced INS-1 cell apoptosis in diabetes.

[Adenovirus-mediated overexpression of thioredoxin interaction protein inhibits INS-1 islet ß cell proliferation].

Diabetes can cause a significant increase in the expression of thioredoxin (Trx)-interacting protein (TXNIP), which binds to Trx and inhibits its activity. The present study was aimed to investigate the effect of TXNIP on proliferation of rat INS-1 islet ß cells and the underlying mechanism. TXNIP overexpressing adenovirus vectors (Ad-TXNIP-GFP and Ad-TXNIPc247s-GFP) were constructed and used to infect INS-1 cells. Ad-TXNIPc247s-GFP vector carries a mutant C247S TXNIP gene, and its expression product (TXNIPc247s) cannot attach and inhibit Trx activity. The expression of TXNIP was detected by real-time PCR and Western blot. EdU and Ki67 methods were used to detect cell proliferation. Protein phosphorylation levels of ERK and AKT were detected by Western blot. The results showed that both TXNIP and TXNIPc247s protein overexpressions inhibited the proliferation of INS-1 cells, and the former's inhibitory effect was greater. Moreover, both of the two kinds of overexpressions inhibited the phosphorylation of ERK and AKT. These results suggest that TXNIP overexpression may inhibit the proliferation of INS-1 cells through Trx-dependent and non-Trx-dependent pathways, and the mechanism involves the inhibition of ERK and AKT phosphorylation.