PRDX1 negatively regulates bleomycin-induced pulmonary fibrosis via inhibiting the epithelial-mesenchymal transition and lung fibroblast proliferation in vitro and in vivo

Jun and JunB members of the AP-1 complex are potential therapeutic targets for silicosis

Silicosis is a systemic disease with predominantly diffuse fibrosis of the lungs due to prolonged inhalation of free SiO2 dust during the manufacturing process, for which there is no effective treatment. In this study, we used a combined epigenetic and transcriptomic approach to reveal the chromatin-opening features of silicosis and identify the key transcription factor activator protein 1 (AP-1) that responds to silicosis fibrosis. Therapeutic administration of an AP-1 inhibitor inhibits the PI3K/AKT signaling pathway, reduces fibrosis marker proteins, and significantly ameliorates lung fibrosis in a mouse model of silicosis. In addition, it was observed that the expression of Jun and JunB was significantly up-regulated in a TGF-β1-induced in vitro transdifferentiation model of NIH/3T3 cells, and Co-IP confirmed that a protein complex could be formed between Jun and JunB. Mechanistically, silencing of Jun and JunB expression reversed the activation of the PI3K/AKT signaling pathway and the upregulation of fibrosis marker proteins in NIH/3 T3 cells after TGF-β1 stimulation. Taken together, Jun/JunB is expected to be a potential therapeutic target for silicosis fibrosis.

18β-glycyrrhetinic acid ameliorates bleomycin-induced idiopathic pulmonary fibrosis via inhibiting TGF-β1/JAK2/STAT3 signaling axis

Idiopathic pulmonary fibrosis (IPF) is a debilitating and progressive lung disease with an unknown cause that has few treatment options. 18β-Glycyrrhetinic acid (18β-GA) is the main bioactive component in licorice, exhibiting anti-inflammatory and antioxidant effects, while also holding certain application value in the metabolism and regulation of steroids. In this study, we demonstrated that 18β-GA effectively alleviates bleomycin (BLM)-induced IPF by inhibiting the TGF-β1/JAK2/STAT3 signaling axis. In vivo experiments demonstrate that 18β-GA significantly attenuates pulmonary fibrosis progression by reducing lung inflammation, improving lung function, and decreasing collagen deposition. In vitro experiments reveal that 18β-GA inhibits the activation and migration of TGF-β1-induced fibroblasts. Furthermore, it regulates the expression of vimentin, N-cadherin and E-cadherin proteins, thereby inhibiting TGF-β1-induced epithelial-mesenchymal transition (EMT) in lung alveolar epithelial cells. Mechanistically, 18β-GA ameliorates pulmonary fibrosis by modulating the TGF-β1/JAK2/STAT3 signaling pathway in activated fibroblasts. Taken together, our findings demonstrate the potential and underlying mechanisms of 18β-GA in ameliorating IPF, emphasizing its potential as a novel therapeutic drug for the treatment of this devastating disease.

FOXF1 reverses lung fibroblasts transdifferentiation via inhibiting TGF-β/SMAD2/3 pathway in silica-induced pulmonary fibrosis

Silicosis is one of the most common and severe types of pneumoconiosis and is characterized by lung dysfunction, persistent lung inflammation, pulmonary nodule formation, and irreversible pulmonary fibrosis. The transdifferentiation of fibroblasts into myofibroblasts is one of the main reasons for the exacerbation of silicosis. However, the underlying mechanism of transcription factors regulating silicosis fibrosis has not been clarified. The aim of this study was to investigate the potential mechanism of transcription factor FOXF1 in fibroblast transdifferentiation in silica-induced pulmonary fibrosis. Therefore, a silicosis mouse model was established, and we found that FOXF1 expression level was significantly down-regulated in the silicosis group, and after overexpression of FOXF1 by adeno-associated virus (AAV), FOXF1 expression level was up-regulated, and silicosis fibrosis was alleviated. In order to further explore the specific regulatory mechanism of FOXF1 in silicosis, we established a fibroblasts transdifferentiation model induced by TGF-β in vitro. In the model, the expression levels of SMAD2/3 and P-SMAD2/3 were up-regulated, but the expression levels of SMAD2/3 and P-SMAD2/3 were down-regulated, inhibiting transdifferentiation and accumulation of extracellular matrix after the overexpressed FOXF1 plasmid was constructed. However, after silencing FOXF1, the expression levels of SMAD2/3 and P-SMAD2/3 were further up-regulated, aggravating transdifferentiation and accumulation of extracellular matrix. These results indicate that the activation of FOXF1 in fibroblasts can slow down the progression of silicosis fibrosis by inhibiting TGF-β/SMAD2/3 classical pathway, which provides a new idea for further exploration of silicosis treatment.

Bletilla striata polysaccharide attenuated the progression of pulmonary fibrosis by inhibiting TGF-β1/Smad signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bletilla striata, a traditional medicinal plant, has been utilized as a folk medicine for many years because of its superior biological activity in China. However, Bletilla striata polysaccharide (BSP) has received less attention, and its specific mechanism for ameliorating pulmonary fibrosis is completely unclear.

AIMS OF THE STUDY

In this study, we aim to assess BSP on the treatment of PF and explore potential mechanisms.

MATERIALS AND METHODS

BSP was successfully extracted and purified from Bletilla striata. The mechanisms were assessed in bleomycin-induced pulmonary fibrosis model and lung fibroblasts activated by transforming growth factor-β1 (TGF-β1). Histological analysis, immunofluorescence, Western blot and flow cytometry were used to explore the alterations after BSP intervention.

RESULTS

The results in vivo showed an anti-PF effect of BSP treatment, which reduced pathogenic damages. Furthermore, TGF-β1-induced abnormal migration and upregulated expression of collagen I (COL1A1), vimentin and α-smooth muscle actin (α-SMA) were suppressed by BSP in L929 cells. Moreover, the abnormal proliferation was retarded by inhibiting the cell cycle of G1 to S phase. Immunofluorescence assay showed that BSP activated autophagy and played an antifibrotic role by inhibiting the expression of p62 and phospho-mammalian target of rapamycin (p-mTOR). Last but not least, the suppression of TGF-β1/Smad signaling pathway was critical for BSP to perform therapeutic effects in vitro and in vivo.

CONCLUSION

The possible mechanisms were involved in improving ECM deposition, regulating cell migration and proliferation, and promoting cellular autophagy. Briefly, all of the above revealed that BSP might be a novel therapy for treating pulmonary fibrosis.

DDAH1 recruits peroxiredoxin 1 and sulfiredoxin 1 to preserve its activity and regulate intracellular redox homeostasis

Growing evidence suggests that dimethylarginine dimethylaminohydrolase 1 (DDAH1), a crucial enzyme for the degradation of asymmetric dimethylarginine (ADMA), is closely related to oxidative stress during the development of multiple diseases. However, the underlying mechanism by which DDAH1 regulates the intracellular redox state remains unclear. In the present study, DDAH1 was shown to interact with peroxiredoxin 1 (PRDX1) and sulfiredoxin 1 (SRXN1), and these interactions could be enhanced by oxidative stress. In HepG2 cells, H2O2-induced downregulation of DDAH1 and accumulation of ADMA were attenuated by overexpression of PRDX1 or SRXN1 but exacerbated by knockdown of PRDX1 or SRXN1. On the other hand, DDAH1 also maintained the expression of PRDX1 and SRXN1 in H2O2-treated cells. Furthermore, global knockout of Ddah1 (Ddah1-/-) or liver-specific knockout of Ddah1 (Ddah1HKO) exacerbated, while overexpression of DDAH1 alleviated liver dysfunction, hepatic oxidative stress and downregulation of PRDX1 and SRXN1 in CCl4-treated mice. Overexpression of liver PRDX1 improved liver function, attenuated hepatic oxidative stress and DDAH1 downregulation, and diminished the differences between wild type and Ddah1-/- mice after CCl4 treatment. Collectively, our results suggest that the regulatory effect of DDAH1 on cellular redox homeostasis under stress conditions is due, at least in part, to the interaction with PRDX1 and SRXN1.

Hepatocytes-derived Prdx1 regulates macrophage phenotypes via TLR4 activation in acute liver injury

Acute liver injury (ALI) is a significant causative factor for multiple hepatic diseases. The excessive inflammatory response triggers proinflammatory immune cells recruitment, infiltration and differentiation, further contributing to inflammatory injuries in liver. As a proinflammatory factor, circulating Peroxiredoxin 1 (Prdx1) is elevated in ALI patients and mice. In this study, through carbon tetrachloride (CCl4) and cecal puncture and ligation (CLP)-induced liver injury mice model, we found hepatocytes-derived Prdx1 expression was increased in ALI. After AAV8-Prdx1-mediated Prdx1 knockdown, CCl4 and CLP-induced ALI was alleviated, along with the reduced proinflammatory cytokines, suppressed myeloid cells recruitment, decreased proportions of hepatic macrophages and neutrophils, restrained proinflammatory macrophage differentiation and infiltration. Mechanistically, hepatocyte-derived Prdx1 regulated macrophages through paracrine activation of the TLR4 signal. Our data support the immune and inflammatory regulatory role of Prdx1 in ALI pathological process to suggest its potential therapeutic application and clinical value.