Influence of the interaction between Ac‑SDKP and Ang II on the pathogenesis and development of silicotic fibrosis

The Role of Tβ4-POP-Ac-SDKP Axis in Organ Fibrosis

Fibrosis is a pathological process in which parenchymal cells are necrotic and excess extracellular matrix (ECM) is accumulated due to dysregulation of tissue injury repair. Thymosin β4 (Tβ4) is a 43 amino acid multifunctional polypeptide that is involved in wound healing. Prolyl oligopeptidase (POP) is the main enzyme that hydrolyzes Tβ4 to produce its derivative N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) which is found to play a role in the regulation of fibrosis. Accumulating evidence suggests that the Tβ4-POP-Ac-SDKP axis widely exists in various tissues and organs including the liver, kidney, heart, and lung, and participates in the process of fibrogenesis. Herein, we aim to elucidate the role of Tβ4-POP-Ac-SDKP axis in hepatic fibrosis, renal fibrosis, cardiac fibrosis, and pulmonary fibrosis, as well as the underlying mechanisms. Based on this, we attempted to provide novel therapeutic strategies for the regulation of tissue damage repair and anti-fibrosis therapy. The Tβ4-POP-Ac-SDKP axis exerts protective effects against organ fibrosis. It is promising that appropriate dosing regimens that rely on this axis could serve as a new therapeutic strategy for alleviating organ fibrosis in the early and late stages.

Metformin attenuates silica-induced pulmonary fibrosis via AMPK signaling

Background

Silicosis is one of the most common occupational pulmonary fibrosis caused by respirable silica-based particle exposure, with no ideal drugs at present. Metformin, a commonly used biguanide antidiabetic agent, could activate AMP-activated protein kinase (AMPK) to exert its pharmacological action. Therefore, we sought to investigate the role of metformin in silica-induced lung fibrosis.

Methods

The anti-fibrotic role of metformin was assessed in 50 mg/kg silica-induced lung fibrosis model. Silicon dioxide (SiO₂)-stimulated lung epithelial cells/macrophages and transforming growth factor-beta 1 (TGF-β1)-induced differentiated lung fibroblasts were used for in vitro models.

Results

At the concentration of 300 mg/kg in the mouse model, metformin significantly reduced lung inflammation and fibrosis in SiO₂-instilled mice at the early and late fibrotic stages. Besides, metformin (range 2–10 mM) reversed SiO₂-induced cell toxicity, oxidative stress, and epithelial-mesenchymal transition process in epithelial cells (A549 and HBE), inhibited inflammation response in macrophages (THP-1), and alleviated TGF-β1-stimulated fibroblast activation in lung fibroblasts (MRC-5) via an AMPK-dependent pathway.

Conclusions

In this study, we identified that metformin might be a potential drug for silicosis treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03036-5.

Clinical efficacy of acetylcysteine combined with tetrandrine tablets on patients with silicosis and its effect on exercise tolerance and pulmonary function

Clinical efficacy of acetylcysteine combined with tetrandrine tablets in the treatment of silicosis was investigated to observe the exercise tolerance and pulmonary function of the patients. The clinical data of 248 cases of silicosis patients treated in Branch of Tai'an City Central Hospital were retrospectively analyzed in this study, including 116 cases with conventional therapy (control group), and 132 cases treated with acetylcysteine and tetrandrine tablets on the basis of conventional therapy (observation group). The chest tightness, chest pain, cough and sputum production were evaluated by the St. George Respiratory questionnaire (SGRQ); and side effects after treatment were recorded. Exercise tolerance was measured by 6-min walk test (6MWT) and pulmonary function was measured by pulmonary function instrument. The symptoms of chest tightness, chest pain, cough and sputum production in the observation group and the control group after 8 months of treatment were significantly lower than those before treatment (P<0.05), and that in the observation group after treatment was significantly higher than that in the control group (P<0.05). The incidence of side effects of the drug in the observation group was significantly lower than that in the control group (P<0.05). The 6MWT, forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1) in the observation group and the control group after treatment were significantly higher than those before treatment (P<0.001); the 6MWT in the observation group after treatment was significantly higher than that in the control group (P<0.001). In conclusion, acetylcysteine combined with tetrandrine tablets on the basis of conventional therapy in treatment of silicosis is more effective than conventional therapy alone, which can also improve exercise tolerance, pulmonary function and clinical symptoms such as chest tightness, chest pain, cough, sputum production of silicosis patients, and is helpful for clinical application.