AMPK attenuates fibroblast-myofibroblast transition via inhibiting HMGB1 during pulmonary fibrosis

Abstract

Abstract

Background: Pulmonary fibrosis(PF), a severe interstitial lung disease, is characterized by the abnormal accumulation of myofibroblasts and extracellular matrix(ECM). Fibroblast-myofibroblast transition(FMT) is responsible for the progression of the PF. AMP-activated protein kinase(AMPK)is a pivotal energy sensor that alleviates or delays the process of fibrogenesis. High mobility group box1(HMGB1) is considered as a crucial mediator of FMT. However, the specific mechanism between AMPK, HMGB1 and FMT has not yet been elucidated in PF.

Methods: SD rats were induced by intratracheal instillation of bleomycin (BLM), and then stimulated with metformin which is an activator of AMPK to observe the effects of AMPK, HMGB1 and FMT markers by western blot and immunohistochemistry. In vitro, human embryonic lung fibroblasts cell lines(HELF and MRC-5) were both treated with metformin, transfected siRNAs of AMPK and HMGB1 to unravel the role of AMPK and HMGB1 and their relationship in TGF-&beta1-induced FMT by western blot.

Results: Treatment with metformin resulted in an amelioration of BLM-induced FMT in rats. Meanwhile, the expression of HMGB1 was significantly increased and accompanied with a lower expression of AMPK in BLM group compared to metformin intervention group. In vitro, TGF-&beta1-induced FMT was clearly inhibited by metformin treatment on HELF and MRC-5. Besides, exogenous TGF-&beta1 was administrated on human embryonic lung fibroblasts with up-regulated HMGB1 and down-regulation of AMPK. Transfected with HMGB1 siRNAs or activated AMPK by metformin ameliorated the progression of FMT. Interestingly, AMPK deficiency by siRNA which is aggravated FMT.

Conclusion: These evidence indicates that the protective effect of AMPK on FMT via inhibiting HMGB1 and provides a therapeutic target for treatment of PF.

Key words: Fibroblast-myofibroblast transition, High mobility group box1, AMP-activated protein kinase

　

Acknowledgements: This work was supported by the National Natural Science Foundation of China (No. 81274172,81473267, 81503330 and 81503129).