| Pulmonary arterial hypertension(PAH)is a kind of progressive pulmonary vascular disease characterized by continuously increasing of pulmonary artery pressure(PAP)and pulmonary vascular resistance(PVR),and the patient will eventually die due to right heart failure without treatment timely.In the past 20 years,it is generally believed that the pathogenesis of PAH is mainly manifested in pulmonary vascular hypercontraction and pulmonary vascular remodeling.Currently,clinically approved drugs targeting PAH mainly focus on vasodilation,while more and more studies have revealed that pulmonary vascular remodeling is the essential feature in the development of PAH.The vasodilation effect of these marketed drugs is weakened with the progression of vascular remodeling although they could temporarily relieve the clinical symptoms of patients,making vasodilator not suitable for long-term treatment of PAH.Therefore,targeted improvement of pulmonary vascular remodeling may be a promising treatment strategy for PAH.Part One: In our early studies,adenosine monophosphate-activated protein kinase(AMPK)inhibitor Compound C and soluble guanylate cyclase(s GC)stimulator Riociguat were used as the lead compounds to design and synthesize a series of pyrazole [3,4-b] pyridine derivatives based on fragment drug design strategy.Subsequently,compound HLQ2 g was finally screened through structure-activity relationship studies for good anti-proliferation activities against human pulmonary artery smooth muscle cells(HPASMCs)and human lung fibroblasts(HLF-1),moderate effect of relaxing rat aortic ring.In order to conduct further studies on the mechanism of action and pharmacodynamics of HLQ2 g for treating PAH,we confirmed the function of HLQ2 g targeting both AMPK and s GC,and investigated the pharmacodynamics in vitro and in vivo.The experimental results showed that HLQ2 g could significantly improve pulmonary vascular remodeling by inhibiting AMPK,and play a vasodilator role by activating s GC.Compared with positive drug Riociguat,HLQ2 g exerted similar efficacy of treating PAH in vivo with different mechanisms of action.Our study results preliminarily proved the feasibility of PAH treatment strategy focusing on improving vascular remodeling accompanied by vasodilation.Part Two: In our previous studies,we found that compound HLQ2 h showed considerable anti-proliferation activities as the position isomer of HLQ2 g in vitro without targeting AMPK,indicating the different regulation mechanism of HLQ2 h.Moreover,we further found that heat shock protein 110(Hsp110)is the potential target of HLQ2 h to inhibit pulmonary vascular cells proliferation via ligand-based target prediction assay.Firstly,we proved that HLQ2 h can directly bind to Hsp110 and affect its functions in vitro through a large number of experiments.Secondly,we explored the changes of Hsp110 expression during the pathogenesis of PAH,and the results suggested for the first time that Hsp110 expression levels were abnormally upregulated in serum of PAH patients and in pulmonary artery and lung tissues of PAH rats.Thirdly,the upregulation of Hsp110 is more significant in human pulmonary vascular endothelial cells(HPAECs),suggesting that Hsp110 may be a new target for pulmonary vascular remodeling.The results of the mechanism study showed that HLQ2 h could regulate Hsp110/signal transducer and activator of transcription(STAT3)related signal pathways to regulate the abnormal proliferation,migration and apoptosis of HPAECs under pathological conditions.Part Three: Previous studies have shown that compound HLQ2 h possesses the potential to be a lead for structure optimization.Hence,we further optimized the structure of HLQ2 h and searched for compound HLQ4 b with stronger activity and better drug-like properties through structure-activity relationship studies.In addition,we also preliminarily studied the mechanism of action and pharmacodynamics of HLQ4 b in the treatment of PAH.The results showed that HLQ4 b could also regulate the abnormal proliferation,migration and apoptosis of HPAECs by interfering Hsp110/STAT3 protein-protein interaction.It is noteworthy that both HLQ4 b and HLQ2 h dramatically inhibited pulmonary vascular remodeling,improved the cardiac hypertrophy index,and reduced the mean pulmonary artery pressure.Moreover,HLQ4 b showed more prominent effects and advantages in treating PAH.Our results preliminarily confirmed that Hsp110/STAT3 interaction is expected to be a novel target for PAH treatment,and further proved the feasibility of treating PAH via improving vascular remodeling meanwhile.In conclusion,the results of this research suggested that the treatment strategy focusing on improving vascular remodeling effectively prevented the progression of PAH and significantly improve the hemodynamic index.Based on in vitro and in vivo experimental data,our study for the first time confirmed that Hsp110/STAT3 interaction is a novel target for PAH therapy from the perspective of regulating vascular remodeling,which provided experimental foundation for breaking through the bottleneck of traditional treatment strategy of vasodilation and creating new strategy for PAH treatment,contributed to the development of first-in-class drug for treating PAH,and possessed important scientific value for developing new PAH therapeutic agents.(74 figures,14 tables,275 references)... |
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